Recalibrating Risks Book Project
Impacts of five nuclear accidents on public attitudes and national
policies in Japan (draft)
Atsuo Kishimoto
Research Institute of Science for Safety and Sustainability (RISS)
National Institute of Advanced Industrial Science and Technology (AIST)
1. Introduction
The accident of Fukushima Daiichi nuclear power plant, operated by the Tokyo Electric
Power Company (TEPCO), was triggered by the 2011 earthquake off the Pacific Coast of
Tohoku. The accident not only changed risk perception of nuclear power of all people,
including experts, politicians, and the general public, but also invited the tightening of
safety standards, the setting of a new regulatory body and the transformation of
national energy policy. Looking back into the past, nuclear power governance developed
as it experienced accidents. This phenomenon where incidents and accidents caused the
change of risk perception of the general public, and subsequently followed by the change
in policies, is widely seen in areas of various safety issues.
From the viewpoint of risk reduction, this chapter discusses the ways in which major
events had impacts on risk perceptions and attitudes of the general public and experts
and how they related to nuclear policies and organizational restructuring, in particular,
the change in governance. The major events that took place outside of Japan, namely,
Three Mile Island (TMI) nuclear power plant accident in 1979 and Chernobyl accident
in 1986, neither led to a shift in domestic regulation policies nor to realignment of
governance, although they did have certain impacts on public perception. The poor
repercussions of these events on Japan explain its delay in preparing countermeasures
for severe accidents in comparison with the United States (US) and European Union
(EU) countries. What is behind the institutional change in Japan was domestic events,
namely, an accident of nuclear ship Mutsu in 1974, a criticality accident at JCO,
Tokaimura, in September 1999, and then, a nuclear power plant disaster at the
Fukushima Daiichi nuclear power plants in 2011. The development of nuclear safety
regulation was chronologically classified by Shiroyama (2010) as follows: the 1st term
dating from 1959 to 1978; the 2nd term dating from 1979 to 1999; and the 3rd term
dating from 1999 onward. To update this classification, the 4th term should start from
1
March 2011 when the accident of Fukushima Daiichi nuclear power plants took place.
The objectives of this chapter is to clarify the development of a nuclear safety regulation
framework through chronologically considering the impacts of major accidents, of which
three took place in the country and two were outside of the country, on public opinions
and policies and regulations in Japan. What follows in Section 2 provides an overview of
Japan’s nuclear policy until March 11, 2011, geographical locations of nuclear power
plants and their implications, and the structure of nuclear power industry. Section 3
considers the background of the enactment of Atomic Energy Basic Act, and the
accident of nuclear ship Mutsu in 1974 and its repercussions. Section 4 deals with TMI
nuclear power plant accident in 1979 and its impact. Chernobyl accident of 1986 is
considered in Section 5, which is followed by Section 6 in which the JCO criticality
accident of 1999 is discussed. Section 7 looks into the 2000s when no major disasters
occurred. Section 8 places its focus on the Fukushima Daiichi nuclear power plant
accident and its repercussion. Section 9 is Discussion.
2. Nuclear power generation in Japan
2.1
Nuclear power policy before March 11, 2011
Nuclear power generation was firstly introduced at the time when post-war years of
recovery grew into a high economic growth period in order to meet a growing electricity
demand, which was thought to increase more than 10% annually at that time. The
introduction of nuclear power generation also served the purpose of diversification of
energy sources and departure from dependence on fossil fuels. The concern about the
dependence on oil was turned into reality by oil crisis of the 1970s. Following this,
Japan started promoting nuclear power, taking it as a “quasi domestically produced
energy.” Encouraging establishment of nuclear power plants, it enacted three Power
Source Development Laws in 1974, i.e., Act on Tax for Promotion of Power-Resources
Development, Act on Special Accounts, and Act on the Development of Areas Adjacent to
Electric Power Generating Facilities. As of 2010, on behalf of the Special Account for
Energy, a tax of power resources development promotion , which is 375 Japanese yen
per 1000kWh, is collected, and is funneled to local communities, towns, cities and
prefectures where a nuclear power plant is located.
The 1980s, which took out after the accident at the TMI, experienced a downturn in
nuclear power use worldwide due to the Chernobyl accident, stabilization of energy
prices, and the rise of an environmental movement. Japanese government, however,
2
remained to adhere to the promotion of nuclear power generation from the viewpoint of
energy security.
Then, in the following decade, nuclear energy was globally reevaluated again. In the
1990s, energy demand from developing countries was rapidly increased, and the need of
reducing global warming gases was widely shared. Emerging countries had begun to
consider building nuclear plants.
In Japan, Ministry of Economy, Trade and Industry (METI) drew up “Basic Energy Plan”
in 2003 based on Basic Act on Energy Policy” which passed Japanese diet in 2002. It
reads:
Nuclear power generation including a nuclear fuel cycle is to be promoted as an
essential power supply, provided that safety is assured, for the reasons that it
contributes to the stability of energy supply and it is the energy of low emission of
carbon dioxide, although it requires strict control.
The second revision of “Basic Energy Plan” in 2010 referred to nuclear power and
renewable energy as “zero-emission power supply”. It claimed that the ratio of
“zero-emission power supply” in electric source, which amounted 34% at that time, was
to be over 50% in 2020, and 70 % in 2030. This ratio was to be achieved by establishing
at least 14 more new nuclear power plants and the improvement of utilization capacity
up to 90%. Figure 1 shows the transition in power supply share in Japan.
3
Oil
Coal
LNG
Nuclear
Hydro
1000
90
900
90
800
305
700
82
500
400
65
10
9
18
300
79
69
67
19
200
0
280
291
600
100
90
69
0
43
51
278
1965
1973
234
159
127
117
57
258
1979
281
192
159
166
1985
1995
253
238
107
68
2005
2009
Figure 1 The transition in power supply share in Japan before 2011 (billion kWh)
2.2 Geographical locations of nuclear power plants in Japan and their characteristics
Japan had 54 nuclear power plants before the Fukushima Daiichi accident (Figure 2).
The number of the plants is currently 50, because Tokyo Electric Power Co. (TEPCO)
decided to abolish 4 power plants in the Fukushima Daiichi site. TEPCO installed
boiling-water type reactors (BWR), while Kansai Electric Power Co. (KEPCO) installed
pressurized-water type reactors (PWR). Every one or two years, electric companies
conduct regular inspections of nuclear power plants. After the earthquake and the
Fukushima Daiichi accident in 2011, the concerns over safety of power plants led
shutdowns of power plants sequentially for inspections. When Hokkaido Electric Power
Co. shut down Japan’s last active nuclear reactor (Tomari power station Unit 3) in May
2012, because of the regular inspection, Japan was without nuclear energy for the first
time in 42 years since 1970. For the fear of electricity shortage, KEPCO restarted two
reactors (Unit 3 and 4) at the Oi nuclear power plants in the summer of 2012. These two
reactors have stopped their operation, however, in September 2013, because the power
plants are required to undergo periodic inspections every 13 months.
4
Figure 2 Nuclear power plants in Japan before 2011 (this figure is tentative)
The manufacture of nuclear reactors has been occupied by oligopolistic three heavy
electric machinery companies, Hitachi, Toshiba and Mitsubishi Heavy Industries. The
company that builds the nuclear power plant undertakes its maintenance and, if needed,
extension of additional facilities. Mitsubishi Heavy Industries had affiliated with
Westinghouse Electric (WH) with the adoption of PWR, while Hitachi and Toshiba had
affiliated with General Electric (GE) with the adoption of BWR. Toshiba obtained
technical information and knowledge to manufacture PWR type plant, as it bought WH
in 2006. Mitsubishi Heavy Industries strengthened its alliance with the French
company AREVA. Units 1 and 4 of Fukushima Daiichi nuclear power station was
manufactured by Hitachi, while Units 2, 3, 5 and 6 were manufactured by Toshiba.
3. Accident of nuclear ship Mutsu
3.1 Start of nuclear energy administration
The history of public administration of nuclear safety in Japan dates back to December
1955 when Atomic Energy Fundamental Act (AEFA) and Atomic Energy Commission
(AEC) Establishment Act were enacted. AEFA had no mention of "safety" until the first
major revision in July 1978. Act on the Regulation of Nuclear Source Material, Nuclear
Fuel Material and Reactors (Nuclear Reactor Regulation Law) was enacted to regulate
safety issues of nuclear power plants in June 1957. The Prime Minister had legislative
authority to give permission of nuclear energy operation, although the Minister of the
5
Science and Technology Agency (STA), who assisted the Prime Minister, had a
substantive regulatory authority. The Director-General of the STA was installed as the
chairman of AEC (Figure 3). AEC, in practice, functioned as a policy-making body,
because its opinions generally accepted by the government, even though AEC was
legislatively a consultation institution as provided in Article 8 of National Government
Organization Act.
Prime Minister's Office
Atomic Energy Commission (AEC)
Chairman = Director-General of the STA
Nuclear Reactor Safety Review Panel
The Secretariat of the AEC
Affiliated agency
Science and Technology Agency (STA)
Atomic Energy Bureau
Commercial power reactors
Ministry of International Trade and Industry (MITI)
Figure 3 Regulatory structure of nuclear safety (1955-1978)
Under this regulatory structure in early years, an electric company applied for
permission to build a nuclear reactor, and submitted a written application form to the
Prime Minister. The Prime Minister consulted AEC on the relevance of the application
to the provisions of Nuclear Reactor Regulation Law. AEC gave instructions to “Nuclear
Reactor Safety Review Panel” set up within AEC to review safety issues. The Panel
reported whether the application met the provisions or not to AEC, which then returned
the report to the Prime Minister. With regard to construction permit by the Prime
Minister, it required the consent of the Minister of the Ministry of International Trade
and Industry (MITI) (Article 71 of the Nuclear Reactors Regulation Law), as reactors
were regulated by the previously passed Electricity Business Act. In addition,
regulatory approvals after reactor construction were permitted were exempted from the
application of the Nuclear Reactors Regulation Law and were left to the Electricity
6
Business Act (Article 73). Against this interwoven governance structure for handling
safety issues, there were already some criticisms at that time. (Tajima 1974).
In April 1970, AEC approved a report by Nuclear Reactor Safety Review Panel titled
“Evaluation Guidance in Safety Design of Light Water Reactors” as legitimate. The
evaluation guidance was revised in 1978.
http://www.aec.go.jp/jicst/NC/about/ugoki/geppou/V15/N05/197004V15N05.html
In the guidance, the design of nuclear reactors was required “to tolerate the most severe
natural hazards that were predicted on the bases of those natural hazards placed in the
record”. This provision is interpreted as a request of zero tolerance. This was backed by
the spirit of the authority and business community who hesitated to assume coming
severe accidents.
The first commercial nuclear power plant launched an operation in July 1966 at Tokai
Power Station of the Japan Atomic Power Company (JAPC), located in Ibaraki
Prefecture. The type of a reactor was a gas-cooled reactor (GCR) developed in the UK,
which was then improved with the addition of earthquake-resistant design introduced
by Japan. In 1970, in Fukui Prefecture, a first BWR Tsuruga-1 Power Plant and a first
PWR Mihama-1 Power Plant started commercial operation. In the following year in
1971, Unit 1 of the Fukushima Daiichi nuclear power plant started to operate. In the
meanwhile, a national survey of 3,000 people was carried out by the Prime Minister's
Office in 1968 and 1969. As shown in Figure 4 only 3 in 1968 and 5% in 1969 of the
general public opposed to the utilization of nuclear materials intended for peaceful
purposes.
1969
Favor
Yes and no
Oppose
I don't know
1968
0%
20%
40%
60%
7
80%
100%
Figure 4 The attitude to the utilization of nuclear materials for peaceful purposes
3.2 A first accident and the public reaction
Japan experienced the first domestic nuclear accident in 1974. A launching ceremony of
the first, and only, nuclear ship Mutsu was held in 1969 at a dock along the Tokyo Bay.
Crown Prince and Princess and the Prime Minister Sato attended the ceremony. In 1974,
Mutsu left the port of Ohminato in Aomori Prefecture for a power ascension test on
August 26 and attained criticality on August 28. The leaking of radiation, however,
occurred when the crew brought the reactor power to 1.4% of full capacity on September
1. The media sensationally reported that “Nuclear ship Mutsu leaked radiation”. As
Aomori Prefecture opposed the return of Mutsu to the Ohminato, Mutsu stayed off
shore for about a month until a compromise was reached by the central government,
Aomori Prefecture, the town of Mutsu and the Aomori Fishery Cooperation, and they
signed the agreement that Mutsu would come back to its home harbor.
A national survey conducted by the Prime Minister’s Office in 1976 on the attitude to
the advancement of nuclear power revealed that 50 % of the respondents considered it
positive, while 15% of them replied negatively and the rest responded that “I do not
know” (Prime Minister’s Office 1976). Another different national survey in 1977
conducted by Mainishi Newspaper showed that 44% of the respondents favored a
further development of nuclear power generation, while 12% of them declined it.
(Shibata and Tomokiyo 1999). Another national survey conducted in 1978 by Asahi
Newspaper found that 55% of the respondents approved the promotion of nuclear power,
while 23% of them disapproved (See section 9). The results of these three polls are
summarized in Figure 5. Overall, the proportion of negative attitude in the 1970s
toward nuclear generation seemed to increase from that in the 1960s, although the
number of those who supported it surpassed that of those who against it. The radiation
leakage from Mutsu seemed to stir public confidence in nuclear power generation.
Protest movements also took place frequently in some residential areas against the
installment of nuclear power plants nearby in the 1970s. The first lawsuit was filed in
1973 against the national government to demand to the repeal of the approval of the
establishment of nuclear power plants in the town of Ikata in Ehime Prefecture.
8
1978
Asahi Newspaper Co.
1977
Mainichi Newspaper Co.
Favor
Oppose
1976
I don't know
Prime Minister's Office
(Cabinet Office）
0%
20%
40%
60%
80%
100%
Figure 5 Public opinion after Mutsu accident in three surveys
In the end of October in 1974, a board of investigation inquiring the Mutsu accident was
launched by the leadership of the Prime Minister, and the investigation report was
issued in May 1975. The report pointed four areas of problems; policy, organization,
technology and contract. In the area of policy, the failure of safety review was referred in
that the Nuclear Reactor Safety Review Panel was not attended by the experts of the
radiation interception design, and all panel members were part-time. It also pointed out
that, the safety checks were only conducted in a written form. The investigation report
claimed that “the panel members tended to produce passable conclusions, blurring the
demarcation between their responsibility for the outcomes and their roles. There
seemed to remain engineering and technical gaps between the examinations and the
real designs".
http://www.aec.go.jp/jicst/NC/about/ugoki/geppou/V20/N05/197524V20N05.html
3.3 Institutional reform after Mutsu accident
With the backdrop of the Mutsu accident, public distrust toward nuclear policy enlarged.
In response to this, the Japanese government established a private advisory committee
under the Prime Minister chaired by Hiromi Arisawa in February 1975 to reexamine
the structure of nuclear-related administrative institutions. The committee submitted
an opinion to the Prime Minister next year. The opinion of Arisawa committee was
summarized in the following three topics.
9
http://www.aec.go.jp/jicst/NC/about/ugoki/geppou/V21/N07/197621V21N07.html
1) To Establish Nuclear Safety Commission (NSC)
The functions related to nuclear safety should be separated from the AEC and moved to
a newly established committee (NSC), which “double-checks" safety reviews carried out
by the competent administrative agencies. NSC is not to regulate electric power
suppliers directly. The legal position of NSC is same as AEC, a consultation institution
as provided in Article 8 of National Government Organization Act.
2) To implement consistent safety regulations
Safety regulations should be consistently applied along the types of reactors, to make
clear responsibility of administrative agencies. The Minister of MITI is to have a
regulatory authority over commercial reactors, the Minister of Transport was to have a
regulatory authority over commercial nuclear ships, and the Prime Minister was to
have a regulatory authority over test reactors. Although regulatory power was
dispersed, the responsibility of the competent administrative agencies is to be clarified
as a result of regulatory integration for each reactor category. This meant, however, that
a role of promotion coexists with a regulative role in the same agencies.
3) To hold public hearings and symposium
In order to mitigate concerns of the public and to promote understanding of nuclear
power generations, the MITI should hold a first public hearing before a decision is made
on the Electric Power Development Basic Plan in the Electric Power Development
Coordination Council when commercial reactors were installed, NSC was to hold a
second public hearing when they perform a "double check" safety review documents
submitted by the MITI.
Based on the recommendations of Arisawa committee, the amendments of both the
Atomic Energy Fundamental Act and the Nuclear Reactor Regulation Law were
submitted to the diet and passed in 1978. NSC was established in October 1978 (Figure
6). Later, NSC is, however, criticized for its emphasis on a “double-check” function in
that NSC’s examination was similar to that by the administrative agency. This could
invite the misperception that NSC supervised the stage of construction only. The other
side of the coin was that the NSC paid less attention to the safety issues in the
operating stage. The double check function might also result in a confusion of
responsibilities for regulatory revisions and updates of examination criteria. (Nishiwaki
10
2011).
Cabinet Office
Atomic Energy Commission (AEC)
Nuclear Safety Commission (NSC)
Nuclear Reactor Safety Review Panel
Nuclear Fuel Safety Review Panel
The Secretariat of the AEC and NSC
Science and Technology
Agency (STA)
Ministry of Economy, Trade and Industry (METI)
Agency for Natural Resources and Energy (ANRE)
Commercial power reactors
Figure 6 Regulatory structure of nuclear safety (1978-2001)
NSC published “Evaluation Guideline for Safety Design of Light Water Nuclear Power
Reactor Facilities” in June 1978, which was the product of full revision of the former
guidance of 1970 by Nuclear Reactor Safety Review Panel.
http://www.aec.go.jp/jicst/NC/about/hakusho/wp1977/ss1010106.htm
Hazards to be considered were listed from Guidance 2 to 6 in the Guideline. Guidance 2
referred to natural hazards. It required that the facilities were designed to withstand
the earthquake motions that were decided by the existing past records and field
investigations on the site and around the region. The detailed requirements regarding
earthquakes were described in “Regulatory Guideline for Reviewing Seismic Design of
Nuclear Power Reactor Facilities” published in the same year. Natural hazards other
than earthquakes included “floods, tsunami, wind (or typhoons), freeze, snow, landslides,
etc. There were no detailed guidances for natural hazards other than earthquake.
Guidance 3 dealt with man-made hazards, such as plane crash, dam collapse, explosions,
etc. These were the guidances for preventing accidents, not for alleviating the damages
of the accidents. In other words, the guidances required zero risk tolerance for nuclear
facilities.
Guidance 9 required the facilities were designed to manage a short-time station
blackout. This, however, was stated that “consideration of the possibility to lose highly
11
reliable power sources” at the same time with the short-time station blackout was not
necessary. In other words, a long-term station blackout was out of the scope of the
assumption. A newly developed “Regulatory Guideline for Reviewing Seismic Design of
Nuclear Power Reactor Facilities” was revised in September 1981 in response to the
revision of Building Standards Act. Safety review of the newly built reactors and
expansions was based on this guideline. . It stated that the facilities “should be with
enough seismic capacity not to induce large accidents against every possible
earthquake”. The emphasis was, therefore, placed on not having accident.
The following procedures were set out;
-
Electric power suppliers examined active faults around the site of the proposed
nuclear facilities. The assessed active faults had its record that dates back at least
50,000 years.
-
Seismic design was determined by seismic motion standards for a plant design
which was calculated by empirical equations for active faults.
-
The seismic motion standards were assessed with the assumption that M6.5
earthquake could occur even where no active fault was found around the site.
-
There was no mention of tsunami that might be accompanied by earthquakes.
As to the existing nuclear reactors, Agency for Natural Resources and Energy (ANRE)
at MITI in 1992 requested electric power suppliers through Federation of Electric
Power Companies of Japan to back-check voluntarily and report the results.
4
Three Mile Island (TMI) accident in the US
4.1 Accident and the public opinion
A loss of coolant accident (LOCA) has occurred at the TMI nuclear power station in the
United States on March 28, 1979. A partial nuclear meltdown was caused because an
operator mistakenly stopped water injection into the reactor core, which was
automatically activated by the emergency core cooling system (ECCS). This accident
was classified as Level 5 on the International Nuclear Event Scale (INES). The lesson of
the TMI accident for global regulatory bodies was that the assumption for severe
accidents in the nuclear power plants caused by multiple failures was needed. It
encouraged the global regulatory bodies to start considering the use of probabilistic
safety assessment (PSA) methods in risk assessment of the facilities. In the meantime,
the TMI accident activated the protest movement against nuclear generation around
the world, while the proponents highlighted that no one was killed in the accident.
12
A national survey was carried out in June and December 1978, which were three
months and six months after the TMI accident by Asahi Newspaper (Shibata and
Tomokiyo 1999, Figure 7). In comparison with the results of national survey before the
TMI accident, the proportion of the respondents who answered favorably slightly
decreased from 55% to 50%. The proportion of the respondents answered negatively
slightly increased from 23% to 29%. Although 67% of the respondents answered in the
affirmative to the question “do you think that nuclear accident that involve the
evacuation of residents will occur in Japan?”, the half of them favored a further
development of nuclear power generation. Furthermore, in the subsequent survey
conducted in December, the proportion of the respondents who favored the nuclear
power increased to 62%. The TMI accident seemed to cause minimal impact on the
public opinion about nuclear power in Japan. This can be explained by the effect of the
second oil crisis in 1979, which showed a high possibility of oil shortage and made
nuclear power more acceptable.
Dec. 1978
Favor
Jun. 1979
Oppose
I don't know
Dec. 1979
0%
Figure 7
20%
40%
60%
80%
100%
Public opinion before and after the TMI accident (Asahi Newspaper)
4.2 Administrative response to the TMI accident
“TMI Accident Investigation Committee of Japan” was established in the Nuclear
Reactor Safety Review Panel in the NSC, and released the first report in May 1979 and
the second report in September 1979. The latter listed 52 items of lessons from the
accident. Namely, : 9 items for safety standards related issues, 4 items for safety
reviewing, 7 items for safety design, 10 items for operations related issues, 10 items for
disaster preventions, 12 items for safety research related issues. Measures preparing
13
multiple fault accidents such as development of PSA methods were, however, classified
as "safety research", not as regulatory actions. This reflected a vertically divided
administrative demarcation between Science and Technology Agency (STA) holding
jurisdiction over research activities and Agency for Natural Resources and Energy
(within MITI) holding jurisdiction over regulations. Later, Nishiwaki (2012) pointed out
three factors that explain why Japan failed to utilize lessons from the TMI accident in
the field of safety regulations.
1) Several administrative lawsuits requiring the revocation of the installation licenses
had been filed against the government at that time. As MITI (Agency for Natural
Resources and Energy) was the central player who granted licenses, it hesitated to
address and incorporate issues beyond design basis accidents into regulatory system.
2) The TMI accident was right after the reorganization of nuclear regulatory system in
response to the Mutsu radiation leakage accident. To make the new system work had a
priority over addressing new challenges.
3) STA, which lost authority to give installation licenses, but was eager to get engaged
nuclear power generations, tried to retain the supervision over safety research. As the
chasm between MITI and STA gradually widened, it became more difficult to bridge
between safety research and regulatory actions.
5．Chernobyl accident in the former Soviet Union
5.1 Accidents and the public opinion
A radiation leakage occurred in April 1981 at Tsuruga power station of the Japan
Atomic Power Co. Because it was revealed that the electric company had tried to cover
up the leakage, public distrust enlarged, even though the amount of radiation leaked
was small. This public distrust was reflected to the outcomes of two national surveys
conducted by the Prime Minister’s Office shortly after the leakage and two and a half
years later. The proportion of the respondents who answered in the affirmative to the
question “do you think appropriate safety measures are adopted at the nuclear power
stations and their associated facilities?” was significantly decreased shortly after the
leakage and remained the same in the latter survey (Figure 8). Another national survey
carried out by Asahi Newspaper in December 1984 showed that the proportion of the
respondents who favored nuclear power was decreased from 55% in 1981 to 47% and the
proportion of the respondents who opposed nuclear power slightly increased from 29%
in 1981 to 32%. The difference between those for and against shrank. It also found that
60% of men but only 35% of women favored nuclear power.
14
Nov. 1980
Yes
Nov. 1981
I don't know
No
Mar. 1984
0%
20%
40%
60%
80%
100%
Figure 8 Public perception of safety measures before and after the radiation leakage
from Tsuruga nuclear power station
Under such circumstance, a severer accident occurred at Unit 4 of Chernobyl nuclear
power station in the Ukraine on April 26, 1986. After a meltdown occurred, it exploded
and its radioactive fallout polluted vast areas in the Ukraine, the Belarus and the
Russia of the Soviet Union. As it was during the cold war era, the first news of the
accident was from north Europe. This accident was rated Level 7 (major accident)
according to International Nuclear and Radiological Event Scale (INES).
In a national survey conducted by Asahi Newspaper in August 1986, for the first time
from 1978, the proportion of the respondents who opposed nuclear power exceeded that
of those favoring it (Figure 9). This situation continued until the mid-2000s. Opinion
surveys carried out by Jiji Press Co. from September 1977 asked the respondents a
question “do you think more nuclear power plants should be built?” (Shibata and
Tomokiyo 1999). The results of this consecutive survey are shown in Figure 9. The
proportion of the respondents opposing nuclear power exceeded that of favoring nuclear
power just after the Chernobyl accident.
15
Chernobyl accident
(Apr. 1986)
Figure 9 Public opinions before and after Chernobyl accident (Jiji Press)
When public opinion surveys data are analyzed by gender, a different result can be
obtained (Figure 10). While the moment when the proportion of the female respondents
opposing nuclear power exceeded that favoring it was December 1984, the proportion of
the male respondents favoring nuclear power has constantly exceeded that opposing it
except in September 1988.
16
Chernobyl accident
(Apr. 1986)
Figure 10 Difference between a man and a woman in the opinion surveys (Asahi
Newspaper)
A national survey conducted by the Prime Minister’s Office in August 1987, however,
showed that only 7 % of the respondents preferred to reduce the number of nuclear
power plants or abandon nuclear power, although 93 % of the respondents had some
knowledge on the Chernobyl accident (Prime Minister’s Office 1987). The Chernobyl
accident seemed to make little or no impact on public opinion in Japan. It was pointed
out, however, that it was not appropriate to simply compare the results of 1984 survey
and that of 1987, for the sentences of questions had been altered (Shibata and Tomokiyo
1999).
5.2 Administrative response to the accident
In response to the Chernobyl accident, Agency for Natural Resources and Energy
(ANRE) in MITI approved "Safety 21 plan" in August 1986, which included the
following items as countermeasures against severe accidents (Nishiwaki 2012).
1) To conduct research and development for the prevention of human errors
2) To conduct analytical research on the behavior of reactors in the event of severe
accidents
3) To develop an impact prediction system for emergency accidents
4) To improvement operation manuals for emergency
17
The second item implied that MITI began to address safety research, which had been
exclusively addressed by STA, paving the way for utilizing them in the regulatory
activities.
At the same time NSC released the first report on the investigation of the Chernobyl
accident in September 1986 and the final report in May 1987. In retrospect, its
conclusion as stated below was too optimistic.
http://www.aec.go.jp/jicst/NC/about/ugoki/geppou/V32/N05/198704V32N05.html
The result of investigation for the present safety measures suggested that it was not
necessary now to revise the current safety regulations and practices in response to the
Chernobyl accident, since the safety of nuclear facilities in Japan had been ensured due
to the diligent efforts at each stage of their design, construction, operation, etc. and
there was no need to change the current framework for preparing natural disasters,
since it had been established according to the intrinsic characteristics of the facilities.
The different attitude of MITI from that of NSC implied lack of cooperation between
these two administrative agencies. Later in July 1987, however, NSC established a
subcommittee on common problems under Special Committee for Nuclear Safety
Standards and ordered to consider the ways to assess and manage severe accidents,
including PSA methods. In March 1992, NSC published a report “Accident Management
as a Preparation for Severe Accidents at Commercial Light-water Nuclear Reactor
Facilities” in May 1992.
http://www.mext.go.jp/b_menu/hakusho/nc/t19920528001/t19920528001.html
In July 1992, MITI changed its policy of introducing regulations for severe accident
measures, but ordered electric utility companies to consider how to prepare severe
accidents by the end of 1993. In other words, the system for severe accident
management was not officially introduced in the Japanese regulatory framework, but
was formed as voluntary measures by electric companies without legally binding
regulations. The completion of this voluntary accident management system was
confirmed in 2002. Except for the above mentioned activities, the 1990s in Japan was
more or less dull with the decline in the motivation for preparing severe accidents
(Nishiwaki 2012). Activities related to safety research on severe accidents also tended to
shrink around the same time.
18
6．JCO accident in Japan
6.1 Accident ant the public opinion
The accident that triggered institutional changes in Japan was not the above mentioned
two major accidents of the TMI and Chernobyl, but the JCO criticality accident occurred
in Tokaimura, Ibaraki Prefecture on September 30, 1999. The accident happened within
a nuclear fuel processing facility of JCO Company which was a subsidiary of Sumitomo
Metal Mining Co., Ltd. In processing nuclear fuels, uranium solution reached criticality
leading to a nuclear chain reaction. Two workers at the plant were killed and one was
seriously injured and more than 600 residents were exposed to radiation. This accident
was classified as Level 4 at INES.
A public opinion survey carried out by ANRE in MITI from 1989, showed an acute
change in perception among the public shortly after the JCO accident, but it more or
less disappeared one or two years later (Mizuho Information and Research Institute
2009). The proportion of the respondents regarding nuclear power as unnecessary
increased from 14.5% before the JCO accident to 21.9% shortly after it. The ratio,
however, soon returned to 16.1% one year later. The proportion of the respondents
answered that nuclear power was not safe increased from 43.1% to 56.6% shortly after
the accident, but it returned to 47.1% one year later, and 40.0% two years later.
http://www.meti.go.jp/meti_lib/report/2009fy01/0018780.pdf
In another public opinion survey conducted by Institute of Nuclear Safety System, Inc.
showed that the proportion of the respondents expressed a high degree of concern about
the possibility of nuclear accidents increased from 27% in 1998 to 36% two months after
the JCO accident (Kitada 2006). The ratio soon returned to the pre-accident level in a
survey one year later by the same institute. The respondents were also asked about the
possibility of occurring Chernobyl-like accident in Japan. The proportion of the
respondents who thought it would happen in Japan in near future increased from 47%
in 1998 to 61% two months after the JCO accident. The ratio, however, has decreased
gradually since, and then fell below the pre-accident level in 2003.
6.2 Administrative response
In response to the JCO criticality accident, NSC established a committee on
investigation of a criticality accident at uranium processing facilities. Based on an
urgent proposal published by the committee on November 5, 1999,
http://www.nsr.go.jp/archive/nsc/senmon/shidai/kakunenryo/kakunenryo016/siryo1.pdf
19
NSC released a document “Immediate Measures for Ensuring Safety of Nuclear Power
Generation” on November 11.
http://www.aec.go.jp/jicst/NC/tyoki/siryo/siryo04/siryo10.htm
The final report of the committee was issued at the end of 1999.
http://www.aec.go.jp/jicst/NC/tyoki/siryo/siryo05/siryo52.htm
At the beginning of the section for actions to be taken, it was pointed out that there was
a major lack of “risk” concept.
Against the backdrop of this accident, risk awareness about critical state was lost in
oblivion. What is important for all organizations and individuals associated with
nuclear power is to retain risk awareness properly. In order for correct risk awareness to
be rooted in society, “the myth of safety” and “absolute safety” needed to be denounced
and change themselves into “risk-based safety assessment”.
The following reforms have been implemented. The JCO criticality accident also
triggered another law called “Act on Special Measures concerning Nuclear Emergency
Preparedness”, which became effective on December 17, 1999. In the act, “article 10
warning” means detections of radiation exposure, which suggested emergencies are
happening or coming. “Article 15 warning” means a high probability of damage of the
reactors such as a loss of all powers or a loss of coolant, in which case the Prime
Minister issues a declaration of a nuclear emergency. The document also pointed out the
need in examining the extent of compliance with the safety regulations after an
approval of installations. Based on a tentative guidance published by NSC in June 2000,
Nuclear Reactor Regulation Act was revised to introduce the inspection system to the
compliance with safety rules.
6.3 Reshuffling of government ministries
These proposals in response to the JCO criticality accident were realized in the
reorganization of governmental ministers and agencies in January 2001. A significant
change was made to nuclear safety regulations (Figure 11).
1) Nuclear reactors and nuclear fuel facilities at the stages of Commercial and R&D
were regulated by the Minister of Economy, Trade and Industry (METI). Commercial
nuclear ships was regulated by the Ministry of Land, Infrastructure and Transportation
(MLIT), while the Ministry of Education, Culture, Sports, Science and Technology
(MEXT) had the authority to regulate test reactors.
20
2) NSC came to be placed under the Cabinet Office and it had their own secretariat
within it. As the administrative status of the Cabinet Office is higher than the other
ministers and agencies, this reshuffling provided it greater independence.
3) Nuclear and Industrial Safety Agency (NISA) was newly established within the
METI (as “a special organization of Agency for Natural Resources and Energy in laws
and regulations). NISA had an extent of independence within the METI, as NISA was a
responsible for safety regulations associated with nuclear power generations.
In the late 1990s, some frauds and accidents in the nuclear industry and its facilities
happened in Japan. Other than the JCO criticality accident, they were a sodium leak
accident at the Monju fast-breeder reactor in 1995, a fire and explosion incident in
Bituminization Demonstration Facility at Tokai Reprocessing Plant in 1997, and a
falsified testing data by a manufacturer of mixed plutonium-uranium oxide (MOX) fuel
in 1999. The government called these problems as “a lack of sound management” and
was urged to consider the way of recovering trust from the public.
http://www.meti.go.jp/report/downloadfiles/g10627ej.pdf
A “task group on nuclear safety” was established to discuss such issues in December
2000. This group was requested to deliberate on the issue “how the future nuclear safety
should be ensured in response to the changes of environment in recent years” and
published a report titled “Securement of Safety Basis of Nuclear Power Generations” in
June 2001.
http://www.meti.go.jp/report/downloadfiles/g10627ej.pdf
http://www.meti.go.jp/committee/materials2/downloadfiles/g90403b09j.pdf
The premise of these efforts was that nuclear power plants in Japan had been equipped
with sufficient safety facilities. The focus was, therefore, placed on to the question how
“safety culture” took root in the nuclear industry.
21
Cabinet Office
Atomic Energy Commission (AEC)
Nuclear Safety Commission (NSC)
Nuclear Reactor Safety Review Panel
Nuclear Fuel Safety Review Panel
Ministry of Economy, Trade and Industry (METI)
Agency for Natural Resources and Energy (ANRE)
Nuclear and Industrial Safety Agency (NISA)
Commercial power reactors
Figure 11 Regulatory structure of nuclear safety (2001-2011)
As a result of the reorganization, a new “double-check” regime was established from the
viewpoint of nuclear safety governance (Figure 11). NSC’s role has been set to oversee
from its unique standpoint the results of the primary safety check done by NISA within
the METI on the basis of Nuclear Reactor Regulation Law. The point of safety check has
been shown in “Evaluation guidance for safety design” including“Regulatory guide for
reviewing seismic design of nuclear power reactor facilities”.
This new system of nuclear safety governance received two international reviews in the
2000s and received positive evaluations including the issue of independence of
regulatory institutions. One review was a national review in 2005 conducted in relation
to the Convention on Nuclear Safety. The other review was by Integrated Regulatory
Review Service of IAEA.
http://www.meti.go.jp/committee/materials2/downloadfiles/g90403b09j.pdf
http://www.nsr.go.jp/archive/nisa/genshiryoku/files/report.pdf
As for the role of NSC, it is said that two different viewpoints have been in Japan
(Siroyama 2010). One was a voice that NSC was not necessary since the function of
“double-check” has been lost its substance. The other was a voice that NSC needed more
independence to ensure safety of nuclear industry. When the form of reorganization of
the governmental ministers and agencies were discussed in November 1999, it is said
22
that the idea of giving NSC more independence had some voices in the Administrative
Reform Task Force of the Liberal Democratic Party (Kitayama 2008).
7．Public opinion and policy development in the 2000s
7.1
Public opinion in the first half of the 2000s
A string of cover-ups scandals at nuclear facilities was reported, starting from the reveal
of TEPCO’s not reporting shroud damage to the government, which had been found in
the voluntary inspection of the nuclear power plants in August 2002. A national survey
conducted by ANRE, MITI showed that the proportion of the respondents who answered
that nuclear power was necessary for Japan decreased sharply from 65% in November
2001 to 50% in November 2002 (Mizuho Information and Research Institute 2009). The
ratio of the respondents who regarded nuclear power plants as safe decreased from 24%
to 11%. The ratio of the respondents who regarded nuclear power plants as unsafe
increased from 40% to 56%. The degree of impact was similar to the JCO accident. The
impact had continued until 2004, three years later according to the same national
survey. On the other hand, another national survey carried out by Institute of Nuclear
Safety System, Inc. in November 2002 showed no impact of cover-ups compared with
the data in 2000 (Kitada 2003). Instead, the proportion of the respondents who
promoted or favored nuclear power showed statistically significant increase between the
above two periods.
Another accident happened at Unit 3 in the Mihama nuclear power station of Kansai
Electric Power Co., Inc. in August 2004. High-temperature vapor erupted because of the
burst of pipes of secondary cooling system. Five workers died from burns suffered over
their whole bodies. Institute of Nuclear Safety System carried out two national surveys
after this accident, two months later and 14 months later. The subjects of the surveys
were 1,500 residents in the supply area of KEPCO. All answers returned to the
pre-accident level, although some statistically significant answers were found in the
survey conducted two months later (Kitada 2006).
On the other hand, it was found that the proportion of the respondents regarded the
nuclear power as unnecessary for Japan increased sharply from 27% in 2003 to 49% in
October 2004 in the ANRE in the METI surveys (Mizuho 2009). It is expected to be an
impact of the Mihama accident. However, the results of the next survey conducted in
January 2006 showed that the answers returned to be pre-accident level.
23
7.2 Public opinion in the latter half of the 2000s
The result of a national survey about nuclear power by Asahi Newspaper showed that
the ratio favoring nuclear power came back to exceed that opposing it for the first time
in about 20 years in the mid-2000s (See Section 9). This trend is also observed in
another national survey conducted by ANRE in the METI (Mizuho Information and
Research Institute 2009). As for the necessity of nuclear power, the proportion of the
respondents who answered that nuclear power was necessary for Japan largely
exceeded that of the respondents who answered that the nuclear power was
unnecessary since October 2006 and the difference continued to enlarge. As for safety,
the proportion of the respondents who answered that the nuclear power was safe
continued to increase since January 2006, and finally exceeded that of the respondents
who answered that the nuclear power was no safe for the first time in 12 years in
August 2008. The proportion of the respondents who would like to promote nuclear
power also exceeded that of the respondents who would like to stop or abolish it since
January 2006.
According to a public opinion survey conducted by the Institute of Applied Energy (IAE)
that asked 500 residents living in the Metropolitan area in person, the ratio of the
respondents who answered that the nuclear power should be abolished has decreased
continually from 35% in 2003 to 16% in 2008, but suddenly increased up to 28% in 2009.
It was interpreted that this change might reflect the fact that the number of the
respondents began to assume that rapid development of new energy sources would
render nuclear energy unnecessary, given the fact that the ratio of other questions
about usefulness, a sense of ease, and trust did not change.
The consecutive national survey carried out by the Atomic Energy Society of Japan
(AES J) also shows that the proportion of the respondents who answered that the
nuclear power was “necessary” or “maybe necessary” for Japan has increased from 68%
in January 2007 to 77% in September 2010, a half year before the Fukushima Daiichi
accident occurred (JAERO 2013).
http://www.aec.go.jp/jicst/NC/iinkai/teirei/siryo2013/siryo23/siryo1.pdf
In general, the latter half of the 2000s appeared to be the time when the public opinion
opting nuclear power had grown. This trend continued until the Fukushima Daiichi
nuclear accident occurred. The proportion of the respondents favoring nuclear power
24
still exceeded that of the respondents opposing nuclear power shortly after the accident
(See Section 9).
7.3 Earthquake countermeasures
“Regulatory Guideline for Reviewing Seismic Design of Nuclear Power Reactor
Facilities” which was issued in 1978 and revised in 1981 used empirical equations
derived from a limited number of data. Seismic motion exceeding the design seismic
motion based on those equations had not been experienced until the Miyagi-Oki
earthquake (M7.2) in 2005. Some experts expressed concerns of underestimating the
design seismic motions after the Hanshin-Awaji (Kobe) earthquake in 1995. NSC began
to collect the new data on the seismic safety of nuclear power facilities in 1996. A
working group on renewal of regulatory guidance for reviewing seismic design was set
up under the Nuclear Reactor Safety Review Committee. As a result of the discussion by
experts on earthquake, geology, architecture, structure and nuclear safety, the new
regulatory guideline was determined in September 2006 after receiving public comment.
Its basic policy stated that “nuclear facilities should be built where its safety functions
are not to be damaged by a seismic motion assumed to occur only infrequently and to
have a large impact on the facilities.”
-
The classes of facilities that are the most important for the seismic safety design (As
and A) are integrated into one class S.
-
Ss, the standard seismic motion, is assumed for both “earthquake ground motion
formulated with a hypocenter specified for each site” and “earthquake ground
motion formulated with no hypocenter”.
-
Multiple earthquakes should be selected for “earthquake ground motion formulated
with a hypocenter specified for each site”. The definition of active faults should be
extended to the faults which activities later than the Late Pleistocene (later than
120-130,000 years ago) cannot be denied.
-
Design earthquake motion Ss is to be determined for each earthquake scenarios by
assessing seismic motions based on both response spectrum and fault model.
-
Design earthquake motion Ss is determined by setting response spectrum based on
the past earthquakes for earthquake ground motion formulated without a
hypocenter specified.
-
Tsunami was referred for the first time as an accompanying event of earthquakes. It
was stated that “nuclear facilities should be built not to be damaged its safety
functions by tsunami, which is appropriate for assuming to occur only infrequently.
25
-
The existence of “residual risks” caused by seismic motions exceeding the design
seismic motion Ss was pointed out. It is written that every effort should be made to
reduce the residual risk as low as reasonably achievable.
While the revised Regulatory Guideline was applied to the newly built nuclear facilities,
NSC asked NISA in the METI to back-check seismic safety of existing nuclear power
facilities in accordance with the new regulatory guidance, although it was not legally
binding. When the 2005 Miyagi earthquake (M7.2) occurred, Units 1 to 3 of Onagawa
nuclear power station was shut down automatically after the earthquake. Seismic
motions exceeding the design seismic motion were recorded in some wave periods,
despite there was no damage caused by the seismic motions. Some of the observed
seismic motions exceeded the design seismic motion in accordance with the old
regulatory guide (S2) at Shiga nuclear power station when the Noto Peninsula
earthquake (M6.9) occurred in 2007. When the Niigataken Chuetsu-oki earthquake
(M6.8) occurred in 2007, 4 units being operated at the Kashiwazaki-Kariha nuclear
power station was shut down automatically and successfully lead to the cold shutdown
conditions, despite observed seismic motions were much larger than the assumed ones
at the design-time at all seven units.
TEPCO submitted an interim report of seismic back-check of Unit 5 at Fukushima
Daiichi nuclear power station in March 2008, which stated that seismic safety ensured
in the assumption that the design seismic motion (Ss) to be 600 Gal. NISA in the METI
confirmed the validity of TEPCO’s assessment in November 2009. Only seven facilities
had been back-checked other than nuclear reactor buildings in the interim report
(National Diet of Japan Fukushima Nuclear Accident Independent Investigation
Commission 2012). TEPCO submitted interim reports on the rest of the units in 2009;
however, the number of covered facilities was similar to the previous one. After the
accident it was revealed that the deadline of report submission was postponed to
January 2016 internally, although TEPCO officially expressed its deadline to be June
2009. It also pointed that TEPCO had realized that a number of seismic strengthening
works should be done to comply with the new regulatory guideline and NISA in the
METI had recognized the urgency of seismic back-check with seismic strengthening
works.
7.3 Tsunami countermeasures
ANRE in MITI instructed the Federation of Electric Power Companies of Japan (FEPC)
26
to assess Tsunami safety of nuclear power stations, responding to the Tsunami damages
including 202 deaths caused by the 1993 southwest-off Hokkaido earthquake (M7.8).
Seven government ministries and agencies jointly published “Guidance to Strength
Tsunami Countermeasures in the Regional Disaster Management Plans”, in which a
new concept called “the assumed largest scale Tsunami” was introduced, but the ways of
assuming it was not described in this guideline. The Japan Society of Civil Engineers
(JSCE), therefore, launched a new group called “Tsunami assessment working group”
and published a report “Tsunami Assessment Techniques for Nuclear Power Stations”
in 2002. In this report, methodologies for assuming tsunami accompanying large
earthquakes were presented.
As noted, tsunami was for the first time explicitly stated in the revised“Regulatory
Guideline for Reviewing Seismic Design of Nuclear Power Reactor Facilities” as an
accompanying event with earthquakes. The countermeasures to prevent tsunami
damages, however, were determined at each nuclear reactor, because the guidance
mentioned neither the specific methodologies to determine the design tsunami, used in
tsunami resistance design for facilities, nor suggested appropriate tsunami proof
design.
TEPCO stated that a margin of safety of 2.5m was guaranteed assuming that the height
above sea level of the lowest cooling seawater pump was 5.6m and the highest tidal level
was 3.122m based on the record of Chile earthquake in 1960 in the construction permit
application of Unit 1 of Fukushima Daiichi nuclear power station submitted in 1964.
Responding to ANRE in the METI instruction in 1993, TEPCO remained the
assumption that the highest tidal level was the one at the Chile earthquake in 1960,
although TEPCO considered 13 tsunami events accompanied by earthquakes since 1611.
In the meantime, Tohoku Electric Power Co., Inc. prepared a construction permit
application of Unit 1 of Onagawa nuclear power station in 1970. In doing so, the height
of the site was set to be 15m, although the highest tidal level assumed based on
literature review and interviews was about 3m. After that, geological investigation and
numerical simulation revealed that the tsunami caused by the 1611 Keicho Sanriku
earthquake was the largest one. The highest tidal level in the site was changed to be
9.1m. The applications of Units 3 and 4 were prepared based on that knowledge.
The Japan Society of Civil Engineers published “Tsunami Assessment Method for
Nuclear Power Plants in Japan” in 2002. TEPCO calculated the height of the largest
27
tsunami at Fukushima Daiichi nuclear power station to be 5.7m applying that guideline.
The cooling seawater pump was raised by 0.2m. The past tsunami events considered in
the assessment was limited to during the last 400 years. Tohoku Electric Power Co., Inc.
also reevaluated the height of the largest tsunami and resulted in 13.6m, which was
confirmed to be less than 15m. The regulatory guideline revised by the NSC in 2006
stated that “nuclear facilities should be built not to be damaged its safety functions by
tsunami that is appropriate for assuming to occur only infrequently” in section 8
“consideration of earthquake accompanying events”. TEPCO water-sealed its cooling
seawater pumps in 2009, as the assumed height of the largest tsunami was changed to
be 6.1m on the basis of the method proposed by the Japan Society of Civil Engineers.
A governmental institution, the Headquarters for Earthquake Research Promotion,
announced “Long-term estimation of Seismic Activities from Sanriku-oki to Boso-oki” in
July 2002. In this report, it was predicted that a M8 class earthquake accompanying
tsunami would occur with a probability of about 20% within 30 years along the Japan
Trench including the offshore of Fukushima Daiichi nuclear power station. TEPCO
simulated the possible impacts of that earthquake and obtained a result that the site of
Fukushima Daiichi nuclear power station would suffer a 15.7m tsunami. TEPCO,
however, did not take any countermeasures at that time.
7.4 Severe accident countermeasures
The TMI accident prompted regulatory agencies in many countries to tackle with
probabilistic safety assessment (PSA) and severe accident countermeasures. The basic
idea was to reduce the probability of occurring core damage accident as far as possible
on the premise that core damage accidents could occur by exceeding the design event or
occurring multiple failure. In doing so, it was necessary to set the safety goals of the
facilities before accidents happened, and to develop response manuals after accidents
happened.
Accident Management (AM) signifies taking both measures to prevent events beyond
the scope of the assumed design scaling up to severe accidents (Phase I) and measures
to mitigate the impact as far as possible when severe accidents occur (Phase II). After
the Chernobyl accident, ANRE in the METI prepared Phase I measures of the AM plan.
In 1992, NSC issued a guideline “Accident Management as a Countermeasure to Tackle
with Severe Accidents at Nuclear Power Facilities”. As the probability of severe
accidents was considered to be very small, AM was not introduced as a legally binding
28
rule, but as a voluntary activity of electricity industry.
Responding to the decision of NSC, ANRE in the METI requested every electric
company to carry out PSA for their reactors. Severe accident countermeasures were
considered, however, only those accidents caused by internal events. Those caused by
external events were never considered even after the Hanshin-Awaji (Kobe) earthquake.
MISA in the METI, established in 2001, reported to NSC that voluntary AM measures
were prepared in 2002. In 2004, NISA in the METI published the results of PSA that
quantified the core damage frequency (CDF) (per reactor per year) and the containment
failure frequency (CFF) (per reactor per year) before and after AM completion (Figure
12).
http://www.nsr.go.jp/archive/nisa/shingikai/800/34/003/sankou4-4-4.pdf
Figure 12 Results of PSA of all 52 reactors (internal events only)
http://www.nuclear.sci.waseda.ac.jp/files/20110715_symposium/1-3.Hirano.pdf
(This figure is tentative one)
Countermeasures to tackle with residual risks have never been positioned as a concrete
regulatory requirement, although the“Regulatory Guideline for Reviewing Seismic
Design of Nuclear Power Reactor Facilities” revised in 2006 by NSC stated that “efforts
29
should be made to reduce “residual risks”1 as low as reasonably achievable, while the
existence of them was sufficiently recognized.” PSA is the most realistic method to
assess residual risks.
To consider how much residual risk should be reduced leads to discussion of safety goals.
NSC released an “Interim Report on Investigation and Deliberation about Safety
Goals“ in 2003.
http://www.meti.go.jp/report/downloadfiles/g31217c10j.pdf
With regard to quantitative goals, it proposed that “an average acute mortality risk of
additional radiation exposure caused by nuclear accidents should not excess 1 in a
million per year for an individual living around site boundary” and “an average
(chronic) mortality risk of additional radiation exposure caused by nuclear accidents
should not exceed 1 in a million per year for an individual living in some distance from
the nuclear facilities.” Subsequently, NSC began discussion of performance targets (core
damage frequency, etc.) compatible with the safety goals.
As for PSA, NSC released a report “Basic Idea for Applying Risk Information to Nuclear
Safety Regulations” in May 2005, and set up basic principles and quality guideline for
PSA in 2006.
http://www.nsr.go.jp/archive/nsc/senmon/shidai/risktask/risktask010/ssiryo4.pdf
The methods of PSA are classified into three levels. Level 1 PSA assesses the occurrence
probability of occurring core damage. Level 2 PSA estimates the occurrence probability
of events releasing radioactive materials and the amount of radiation dose. Level 3 PSA
assesses the health impact of released radiation dose on the general public living near
the facilities. Safety goals were applied to Level 3 PSA and performance targets were
applied to Levels 1 and 2 PSA.
8．Impact of the accident at the Fukushima Daiichi nuclear power plants
8.1
Accident and the public opinion
When the Tohoku earthquake happened on March 11, 2011, Units 1, 2 and 3 in
Fukushima Daiichi nuclear power station were in operation, while Units 4, 5 and 6 were
under suspension due to a periodic inspection. Emergency shutdown systems were
successfully worked at the three units in operation. All units lost external power supply,
”residual risks” are defined as the “risks of occurring severe damages to facilities,
releasing a large volume of radioactive materials from facilities, and exposing
radioactive materials to the public around the facilities by the impact of seismic motions
exceeding the design seismic motion.”
1
30
however, as the seismic motion damaged the electricity transmission and distribution
facilities, which halted all transmission of electricity. All power sources except for one
air-cooled emergency diesel generator at Unit 6 were lost by the tsunami occurred
shortly after the earthquake. Following that, hydrogen explosions at Units 1, 3 and 4
and core damages at Units 1, 2 and 3 took place.
The direct contributing factors that invited the accident were the following. First, the
update of the existing reactors to comply with the 2006 revised regulatory guide, i.e.,
the back-fitting, was postponed, as mentioned in section 7.3. Second, although tsunami
risk was recognized, the government failed to address tsunami risks based on a
long-term assessment published by the Headquarters for Earthquake Research
Promotion of the government, as also mentioned in section 7.3. Third, the accident was
attributed to the unrealistic premise for severe accident countermeasures that did not
assume external events, such as earthquakes and tsunami. In other words, the root
cause common to all three direct causes is the problem of regulatory capture. The
following aspects were pointed out in various accident analysis reports.
-
Electrical power suppliers have become involved in making safety regulations by
strong ties with regulatory bodies.
-
Regulatory agencies have had both regulatory sections and promotion sections
within the same agencies.
-
As regulators and the regulated shared the same interest in avoiding the shutoff of
existing reactors, they have tried to ignore the opinions to deny the validity of the
safety of the existing reactors and the past regulations.
Certainly, the accident increased risk perception of the general public. The proportion of
the respondents favoring nuclear power, however, still exceeded that opposing it in
opinion surveys conducted shortly after the accident in March and April 2011 except for
several surveys (Figure 13 and footnote2).
2
According to a telephone survey conducted by Asahi Newspaper from April 16 to 17,
2011, the proportion of the respondents favoring nuclear power was 50% and that
opposing it was 32%. About half of the respondents favored the status quo to the
question asking them how to do with the nuclear power plants in Japan. According to
the telephone survey conducted by Yomiuri Newspaper from April 1 to 3, 2011, 10%
agreed with the increase in the number of nuclear power plants, 48% favored the status
quo, 29% supported the decrease in the number of nuclear power plants, and only 12%
31
Figure 13 Change in public opinion after the accident (Asahi Newspaper)
There appeared to be several factors to explain why the proportion favoring nuclear
power had exceeded that opposing it in April, one month after the accident. The high
ratio supporting nuclear power in the latter half of the 2000s might leave some
influence on the public opinion. In addition, the following circumstances seemed to
contribute to the support for nuclear generation.
-
The public was not aware of the fact that radioactive materials polluted widespread
areas and their effects would continue for a long time.
-
The accident was recognized as a natural disaster rather than a human-made
disaster.
favored the abolishment of them. The results of the telephone survey carried out by Pew
Research Center in April and May 2011 also showed that 8% favored the increase in the
number of nuclear power plants, 46% supported the status quo, and 44% supported the
decrease in the number or abolishment of the nuclear power plants.
http://www.pewglobal.org/2012/06/05/japanese-wary-of-nuclear-energy/
In the meantime, WiN Gallup International, for instance, conducted an opinion survey
with 34,000 people in 47 countries on March 21 to April 10, 2011. Japan’s part included
1,000 people who were asked to answer via Internet on 5 to 8 April. It showed that
before the earthquake and the accident, 62% of the respondents saw nuclear power
generation favorably, while 28 % of them saw it unfavorably. At the time of survey,
however, 39 % found themselves in responding they have favorable attitude, while 47 %
in unfavorable attitude.
http://www.nrc.co.jp/report/pdf/110420_2.pdf
32
-
Possible electricity shortage was an urgent matter at that time.
In opinion surveys from May 2011, it became clear that the majority of the public
opposed nuclear power and this has still continued in 2013 (see footnote3).
3
The proportion of the respondents opposing nuclear power (46%) exceeded that
favoring it (37%) for the first time since mid-2000s in a telephone survey conducted by
Asahi Newspaper in June 11-12, although the former (36%) was smaller than the
latter (43%) in May. This trend has been continuing since then. In surveys conducted by
Yomiuri Newspaper, 44% of the respondents preferred to reduce the number of nuclear
power plants, 15% of them hoped to abolish all. That is, 59% of the respondents opposed
nuclear power. After that, the ratio has gradually increased. The NHK Broadcasting
Culture Research Institute made a continual telephone survey of the public opinions
from June 2011. Only 1 - 3% preferred to increase the number of nuclear power plants.
While 20 - 30 % of the respondents supported the status quo, 40 - 50% of them preferred
to reduce and 10 – 30 % insisted on abolishing the nuclear power. This has not changed
for two years since the accident.
https://www.nhk.or.jp/bunken/yoron/social/index.html
Nippon Research Center carried out public opinion surveys in May, July and September
2011 and March 2012 by the door-to-door placement method (Nippon Research Center
2012). They asked 1,200 people a question asking about using nuclear power as one of
the energy sources. The proportion of opponents increased from 45% in May 2011 to
57% in March 2012, while the proportion of supporters continued to decrease from 33%
in May 2011 to 24% in March 2012.
http://www.nrc.co.jp/report/120330_1.html
Ispos also conducted an online survey with 18,787 people in 24 countries on May 6-21,
2011, in which more than 1,000 people in Japan responded. 41 % of them answered they
support nuclear generation; of which 5 % said they supported strongly and 36 % said
they more or less supported. Those who opposed it amounted to 58 % whose 30 %
opposed more or less and 28 % opposed strongly. Among those who answered that they
were opposed, 52 % of them said they had changed their opinion recently.
http://www.ipsos-mori.com/researchpublications/researcharchive/2817/Strong-global-op
position-towardsnuclear-power.aspx
An opinion survey was carried out by GlobeScan with 23,231 people in 23 countries
from June to September 2011. A face-to-face interview was conducted in Japan with
1673 people on September 3-4. This is comparable with the survey of 2005. The ratio of
those who supported the construction of new nuclear power stations decreased from
33
8.2 Launch of the NRA
The government classified lessons from the accident thus far into five categories in the
report submitted to IAEA in June 2011 (Nuclear Emergency Response Headquarters
2011). The lesson in Category 1 suggested the need to strengthen preventive measures
against a severe accident. The lessons in Category 2 implied the need to enhance
response measures against severe accidents. Category 3 lessons concerned the
enhancement of nuclear emergency responses. Category 4 pointed the need to reinforce
safety infrastructure. Category 5 requested a safety culture to be thoroughly instilled.
Among them, Category 4 stated that “NISA should be separated from the METI and the
regulatory structure of nuclear power should be re-examined including NSC and
associated agencies.” In August 2011, the cabinet approved “Basic Policy on
Institutional Reform of Nuclear Safety Regulation”, in which NISA was removed from
the METI and integrated into Nuclear Safety Agency (tentative) with the functions of
NSC as an affiliated agency of the Department of Environment. The government
submitted a proposed legislature that moved NISA from the METI to an affiliated
agency of the Department of Environment (DOE) and created nuclear safety council as
an advisory committee (section 8 of National Administrative Organization Act) at the
end of January 2012.
Against this reform, then the opposition Liberal Democratic Party launched a project
team on nuclear regulatory institutions in December 2011 and began to make a counter
offer from a position placing more weight on independence. As a result of discussion, the
opposition parties submitted a counter legislative proposal in April 2012. This proposal
was adopted in full scale and was enacted as “Act for Establishment of the Nuclear
Regulation Authority” in June 2012.
21 % to 6 %, while those who supported their earlier disclosure increased from 15 % to
27 %.
http://www.globescan.com/commentary-and-analysis/press-releases/press-releases-2011
/94-press-releases-2011/127-opposition-to-nuclear-energy-grows-global-poll.html
National Institute of Science and Technology Policy (NiSTEP) asked internet monitors
questions about their attitude toward the use of nuclear power in the future every
month from April 2011 to February 2012 (NiSTEP 2012). The proportion of the
respondents favored the abolishment of nuclear power doubled from 11% in April 2011
to 23% in February 2012.
http://data.nistep.go.jp/dspace/handle/11035/1156
34
-
NSC in the Cabinet Office and NISA in the METI were abolished. Their functions
were integrated into the newly established Nuclear Regulatory Authority (NRA).
-
Functions dispersed in various departments and agencies were integrated in NRA,
including nuclear safety regulations, nuclear materials security, safeguards of
non-proliferation, radiation monitoring, and regulations of radioactive isotopes.
At the same time, Nuclear Reactor Regulation Law was also revised and regulations of
nuclear power reactors changed as follows.
-
Severe accident countermeasures were legally required.
-
Back-fitting of the newest knowledge to the existing facilities was legally required.
-
Extension of the operation period less than 20 years was permitted only once.
The NRA was launched on September 19, 2012 (Figure 14). The NRA was an external
organ of the Ministry of the Environment. The NRA consists of the Chairman and four
other commissioners. The Secretariat of the NRA has 473 staffs, as of March 31, 2013.
The NRA integrated several tasks that were separated in various administrative
institutions (Table 1).
Table 1 Major affairs under the Jurisdiction of the NRA
(1) Ensuring safety in the use of nuclear energy (Regulations on nuclear energy-related
business and facilities, and on the use of nuclear fuel material, etc.)
(2) Regulations on physical protection of nuclear material (nuclear security) and related
issues among relevant ministries and agencies
(3) Adjustment of affairs among relevant ministries and agencies concerning radiation
monitoring
(4) Fostering human resources to ensure nuclear energy safety
(5) Investigation of causes of nuclear reactor accidents and resultant damage.
(6)Formulation of Nuclear Emergency Response Guideline, etc.
(7)Regulations on safeguards based on international commitments
(8)Prevention of radiation hazards (regulations on radioisotopes, etc.)
(9)Implementation of radiation monitoring
http://www.nsr.go.jp/english/data/ar_0701.pdf
35
Cabinet Office
Atomic Energy Commission (AEC)
Nuclear Regulation Authority
(NRA)
Ministry of Economy, Trade
and Industry (METI)
One chairman
Four commissioners
Agency for Natural Resources
and Energy (ANRE)
The Secretariat of the Nuclear
Regulation Authority
473 officials
Department of Environment
Commercial power reactors
Figure 14 Regulatory structure of nuclear safety (2012-)
8.3 New safety design and re-start of nuclear power plants
The NRA set up several teams to develop new regulations for nuclear power stations. A
“draft outline” of new safety standards was placed for public comment from February 7
to 28, 2013.
http://www.nsr.go.jp/public_comment/bosyu130206.html
The teams examined the comments, and then, the new regulatory requirements draft
was developed into 49 documents, which were again placed for public comment from
April 11 to May 10, 2013.
http://www.nsr.go.jp/public_comment/bosyu130410_02.html
The new regulatory requirements were approved on June 19, and published on July 8,
2013. The difference between the old and the new one is shown in Figure 15.
The newly developed safety standards consider severe accidents. The scope of “external
events to be taken into account” and the level of “design basis of the external events”
was also discussed by one of the task teams. External events consist of natural disasters
and external man-made events. Regulatory guidance for natural disasters targeted
volcanic eruption, tornado, and forest fire, in addition to earthquake and tsunami.
External man-made events were divided into incidental events, such as aircraft crash
and dam fail, and intended events, such as terrorist attacks.
36
Figure 15
Structure of new requirements compared with the old ones
http://www.nsr.go.jp/english/data/20130620_presentation.pdf
(This figure is a tentative one)
More stringent standards on tsunami
The design tsunami, used in tsunami resistance design, set as the one that caused the
largest damage to the facility among the possible tsunami scenarios based on the wave
source model considering occurrence factors and the diffusion simulation. Then, based
on a probabilistic tsunami hazard assessment, the probability of exceeding water level
of the design tsunami is derived for the assessment site.
http://www.nsr.go.jp/nra/kettei/data/20130628_jitsuyoutsunami.pdf
When NISA in the METI discussed an acceptable level of that probability, it was
proposed that the frequency of exceeding the design tsunami should be kept below
10-5/year the in order to keep the frequency of core damage below 10-4/year. The safety
goal, however, was not proposed in the new safety regulations.
http://www.nsr.go.jp/archive/nisa/shingikai/800/26/023/240907.html
37
Figure 16 Active faults (approx. 2000 identified) and nuclear power plants in Japan
http://www.nsr.go.jp/english/data/20130620_presentation.pdf
(This figure is tentative)
New requirement for volcanic activities
Electric companies will be forced to assess and take account of volcanoes within a
160-kirometer radius. The covered volcanoes are the ones that have been active since
the Quaternary period (about 2.58 million years ago). 160-kirometer was determined by
reference to the past longest distance of fallen volcanic products. Among them, the
volcano active after the Holocene (about 10,000 years ago) are regarded as the ones that
may become active in the future. Figure 1 shows the map of 110 volcanoes active since
10,000. When the frequency of damaging the nuclear power plants by the volcanic
events beyond the design one will not be regarded as sufficiently small, the nuclear
power plants will not be permitted. The following are considered as volcanic events; the
fall of pyroclastic materials, pyroclastic flow, lava flow, debris avalanche, land slide and
slope failure, mudslide, volcanic mud flow and flood, ash deposit, and the emission of
volcanic gas.
38
Figure 17 Volcanos and the nuclear power plants in Japans
The number of active volcanoes was 110 in June 2011
http://www.nsr.go.jp/english/data/20130620_presentation.pdf
(This figure is tentative)
After enforcement of the new safety regulations, the NRA started compatibility reviews
for nuclear power plants responding to the application from electric power companies.
Four companies applied for receiving a compatibility review to 12 nuclear power plants.
The NRA reached a consensus on the safety goals. A safety goal was defined as a goal
that NRA was trying to achieve as it regulated nuclear facilities. The interim report was
published in 2003 after a working group discussion on safety goals, which has not been
held since then. It was written that the starting point was that the frequency of core
damage was about 10-4/year and that of loss of function of a containment vessel was
about 10-5/year. It was concluded that the frequency of occurrence probability for a
major accident that released more than 100 TBq of Cs137 should not exceed 1 in 1
million reactor years (excluding man-made disasters). The discussion about safety goals
was to be continued.
8.5 Impact on other nuclear power plants
On May 6, 2011, the Prime Minister Kan requested Chubu Electric Power to halt the
operation of Hamaoka nuclear power station that had 3 operating units through then
the Minister of the METI.
http://www.meti.go.jp/press/2011/05/20110506006/20110506006.pdf
39
Chubu Electric Power decided to halt the operation of Units 4 and 5 on May 9, even
though the request was without legally binding power. Chubu Electric Power had
planned to restart Unit 3 that had been placed under a regular inspection since October
2010 in April 2011. In the aftermath of Fukushima Daiichi accident, it postponed the
restart to July 2011 and then announced its deferment for the time being on May.
The assumed height of tsunami before the Fukushima Daiichi accident had been set as
8 m, which was derived from the scenario of a possible earthquake in the Nankai trough
in the Pacific Ocean on basis of the past geological records and the result of simulations,
and was considered to be protected by the 10-15m high sand dune. Five days after the
Fukushima Daiichi accident, they announced a plan to build a 12-meter high and 1.2
km long tsunami defense wall within 2 or 3 years (Jiji Tsushin on March 16). They
revised its height from 12m to 15m in order to relieve the residents’ concern one month
later. Then, they decided to increase its height and to build an 18-meter high and 1.6 km
long tsunami defense wall in July, on the basis of the observed 15-meter height of the
tsunami at the Fukushima Daiichi site. Finally, they decided to add a 4-meter iron sheet
to the 18-meter high wall under construction responding to the revised scenario of the
possible Nankai trough earthquake that could cause a 19-meter high tsunami at the
site of Hamaoka nuclear power plants, which corresponded to be 21.4-meter run-up
height. This tsunami defense wall was announced to be finished by the end of 2013
Figure 18).
Figure 18 Tsunami protection wall construction at Hamaoka site
http://hamaoka.chuden.jp/english/provision/tsunami_plant.html
Electric companies have not decided to resume every other nuclear power station after
regular inspections. As a result of that, the ratio of power sources has been shown in
40
Figure 19.
Coal
Nuclear
Figure 19
LNG
Nuclear (%)
Oil
Thermal (%)
Hydro
Shift in proportion of power sources of electric power suppliers
8.6 Impact on energy policy
“Guidance on Policy Promotion: toward rebirth of Japan” was decided by the Cabinet on
May 17, 2011, which ordered a newly established cabinet meeting called “Energy and
Environment Council” chaired by the State Minister for National Strategy to formulate
a new “Innovative strategy for energy and environment”. The Prime Minister expressed
intent to undo the current “Basic Energy Plan” revised in 2010.
The Council published an “Interim Summary” in the 2nd meeting at the end of July. This
document presented three basic ideas, 1) to reduce the dependence on nuclear energy, 2)
to shift toward distributed system, and 3) to move toward a national discussion. The
“Basic Policy” was published in the 5th meeting at the end of December.
http://www.meti.go.jp/committee/summary/0002015/017_s01_00.pdf
The Council requested the AEC to develop options of nuclear energy policy, the Advisory
Committee on Energy and Natural Resources in the METI to develop options of energy
mix, and the Central Environment Council in DOE to develop options of global warming
policy by next spring on the basis of the “Basic Policy”. These results were reported to
the Council on June. Then, the government determined the “Options for Energy and the
Environment”, preparing three options, (1) 0% scenario, (2) 15% scenario, and (3)
20-25% scenario on the basis of dependence on nuclear energy as of 2030.
41
http://www.cas.go.jp/jp/seisaku/npu/policy09/sentakushi/pdf/Report_English.pdf
(in
English)
The “National Discussion” based on the three options was implemented on July and
August 2012. It consisted of public hearing sessions, solicitation of public comment and
a Deliberative Polling (DP). In parallel with them, mass media carried out various
national opinion surveys. These results were summarized in Figure 20.
Figure 20 Results of various opinion surveys in summer 2012
http://www.cas.go.jp/jp/seisaku/npu/policy09/pdf/20120904/shiryo1-2.pdf
Responding to the high public support for the 0% scenario, the Democratic Party of
Japan (DPJ) government finally published the “Innovative strategy for energy and
environment”.
http://www.un.org/esa/socdev/egms/docs/2012/greenjobs/enablingenvironment.pdf
(in
English)
In this document, the following three guiding principles were presented in order to
achieve the goal of no dependence on nuclear power by the 2030s.
1) To strictly apply the stipulated rules regarding forty-year limitation of the operation;
2) To restart the operation of nuclear power plants once the Nuclear Regulatory
Authority (NRA) gives safety assurance;
3) Not to plan the new and additional construction of a nuclear power plant, are the
guiding principles
The Lower House election took place on December 16, 2012, which was the first general
election since the Fukushima Daiichi accident. The Liberal Democratic Party (LDP)
achieved a sweeping victory, securing 294 seats and taking over government from the
DPJ, which kept only 57 seats. The LDP decided to rescind the “Innovative strategy for
42
energy and environment”. In a policy address on February 28, 2013, the Prime Minister
Abe clearly stated that they would like to restart nuclear power plants that passed the
safety evaluation. A half year later, the Upper House election took place on July 21,
2013. The LDP achieved a sweeping victory again. The revised “Basic Energy Plan” will
be determined by the end of 2013, in which the nuclear power is said to be positioned as
an important power source.
Both elections resulted in major victories for the LDP and its coalition partner who
expressed intent to restart nuclear power stations, although public opinion surveys
showed a strong opposition to nuclear power. This seems to be strange, but might be
explained in two ways. One is the artificial effect of the voting system. The voting
system of the Upper House election consists of 73 seats elected in 47 electoral zones and
48 seats elected in the proportional representation. The share of the vote of the LDP and
its partner New Komeito was 48.9%, which means that half of the voters supported the
various parties against nuclear power. Figure 21 shows the shift in party’s share of the
vote in the proportional representation.
45%
Liberal Democratic
Party of Japan
40%
35%
Democratic Party of
Japan
30%
25%
Japan Restoration
Party
20%
New Komeito
15%
10%
Japanese Communist
Party
5%
Your Party
0%
2005. 2007. 2009. 2010. 2012. 2013.
HR
HC
HR
HC
HR
HC
Figure 21 Shift in share of the vote in the proportional representation
Another explanation is the fact that about half of the public is ambivalent about the
nuclear power. The majority of people seem to oppose the restart of the nuclear power
plants because the proportion of the respondents opposing the restart was 58% and that
favoring it was only 28% in a telephone survey conducted by Asahi Newspaper just
before the Upper House election. In a telephone survey carried out by NHK on March
43
2013, however, 45.5 % of the respondents selected the “no opinion” option while 35.5%
opposed the restart and 15.9% supported it, although the former survey had only two
response
alternatives
(NHK
Broadcasting
Culture
Research
Institute
2013).
Furthermore, a gradual rise in home electricity bills might have some impact on public
attitude toward nuclear power.
9. Discussions
The time series variation of public opinion for nuclear power in Japan is summarized in
Figure 22. Data comes from public opinion surveys carried out by Asahi Newspaper.
Four accidents out of the five major accidents mentioned in this chapter took place
within this time frame. It was 1986, the year Chernobyl accident, when the proportion
of the respondents opposing nuclear power exceeded that favoring it. The gap between
those who were for and those against shrunk during the 1990s, although the JCO
accident had some impact. In the mid-2000s, the proportion of the respondents favoring
nuclear power again exceeded that opposing it, which had continued until the
Fukushima Daiichi accident. The proportion of the respondents opposing nuclear power
exceeded that favoring it in June 2011, three month after the accident. The gap has
enlarged since then.
44
TMI accident
(Mar. 1979)
JCO accident
(Sep. 1999)
Chernobyl accident
(Apr. 1986)
Fukushima Daiichi
accident
(Mar. 2011)
Figure 22 Time series variation of public opinion and major accidents
This figure was drawn up on the basis of the survey results by the Asahi Newspaper Co.
Impact of five major accidents focused on in this chapter on public opinions and
regulatory policies was summarized in Table XX.
Table 2 Impact of major accidents on public opinions and regulatory policies
Impact on public opinions
Impact on regulatory policies
Mutsu
＋
＋
TMI
－
－
Chernobyl
＋
－
JCO
－
＋
＋＋
＋＋
Fukushima Daiichi
References should be added here.
45
Abbreviations
AEC: Atomic Energy Commission
AM: Accident Management
ANRE: Agency for Natural Resources and Energy (within MITI or METI)
BWR: boiling-water type reactors
CDF: core damage frequency
CFF: containment failure frequency
DOE: Department of Environment
DPJ: The Democratic Party of Japan
FEPC: Federation of Electric Power Companies of Japan
INES: International Nuclear and Radiological Event Scale
KEPCO: Kansai Electric Power Co. Inc.
LDP: The Liberal Democratic Party
METI: Ministry of Economy, Trade and Industry (2001-)
MEXT: Ministry of Education, Culture, Sports, Science and Technology
MITI: Ministry of International Trade and Industry (-2001)
MOX: mixed plutonium-uranium oxide
NISA: Nuclear and Industrial Safety Agency (within MITI or METI)
NSC: Nuclear Safety Commission
PSA: probablistic safety assessment
PWR: pressurized-water type reactors
STA: Science and Technology Agency
TEPCO: Tokyo Electric Power Co. Inc.
TMI: Three Mile Island
46