6th Asia-Pacific Symposium on Radiochemistry
September 17 ~ 22, 2017 • ICC Jeju • Jeju Island,
Republic of Korea
INSIGHTS INTO RADIOLOGICAL IMPACTS FROM MAJOR
SEVERE ACCIDENTS OF NUCLEAR POWER PLANTS
Inn Seock Kim1, Tae Won Kim2, Mi Suk Jang3, Ki Ho Park4, Seoung Rae Kim5
1
NESS: No.704, 96 Gajeongbuk-ro, Yuseong-gu, Daejeon, 34111, Republic of Korea, [email protected]
KAERI: 111, Daedukdae-ro 989, Yuseong-gu, Daejeon, 34057, Republic of Korea, [email protected]
3
NESS: No.704, 96 Gajeongbuk-ro, Yuseong-gu, Daejeon, 34111, Republic of Korea, [email protected]
4
NESS: No.704, 96 Gajeongbuk-ro, Yuseong-gu, Daejeon 34111, Republic of Korea, [email protected]
5
NESS: No.704, 96 Gajeongbuk-ro, Yuseong-gu, Daejeon, 34111, Republic of Korea,[email protected]
2
This paper provides insights into the radiological impacts of several severe accidents that occurred at nuclear
power plants. Of those severe accidents reviewed herein, the accidents at Chernobyl and Fukushima resulted in the
largest release of radioactivity and exposure doses. It was primarily brought about by the lack of robust containment
structure at Chernobyl and the simultaneous occurrence of several core damages as a consequence of strong earthquake
and concomitant tsunami at Fukushima. The insights can be used for various applications such as determination of safety
goals for nuclear power plants in terms of radiological consequences as well as the expected likelihood of occurrence,
development of the emergency management program, or performance of a probabilistic safety assessment (PSA).
I. OBJECTIVE
Nuclear power plants are designed and operated as safely as possible. However, nuclear accidents do occur once in a
while as can be seen in the operational record of the worldwide nuclear power plants. A recent review of the operational
record indicates that more than 440 major radiation accidents have occurred worldwide during the past seven decades [1].
It is important to understand the extent of the consequences of these radiological accidents, because the insights
thereof can be used for various purposes such as determination of safety goals for nuclear power plants in terms of
radiological consequences as well as the expected likelihood of occurrence, development of the radiological emergency
preparedness program, and so on. The objective of this study is to gain insights on the radiological impacts of several
major nuclear accidents.
II. METHODS
A review of the open literature on the five major accident mentioned above was made including Refs. [1-3]. As
shown in Table I, The Chernobyl and Fukushima accidents have been rated as the highest grade of 7 in terms of the
International Nuclear and Radiological Event Scale (INES), implying that they resulted in the most serious radiological
consequences. In our study, we focus on the following five major accidents:
1. Kyshtym, Russia, 1957: Chemical explosion of containment tank of liquid radioactive wastes at military
installation
2. Windscale Piles, UK, 1957: Fire of nuclear reactor at military installation designed to produce plutonium
3. Three Mile Island, USA, 1979: Partial core melt at civilian nuclear reactor
4. Chernobyl, Ukraine (then USSR), 1986: Core explosion and fire at civilian nuclear reactor
5. Fukushima, Japan, 2011: Core melt-through; three reactor cores damaged; three reactor buildings hydrogen
explosions
A comparison of the estimated amount of radioactivity released and dose exposed for these two accidents points out
the following things among others. First, the Chernobyl and Fukushima accidents resulted in considerable amount of
volatile/semi-volatile fission products such as Iodine-131 or Cesium-137 causing early and long-term health effects. In
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6th Asia-Pacific Symposium on Radiochemistry
September 17 ~ 22, 2017 • ICC Jeju • Jeju Island,
Republic of Korea
particular, it is notable that the Chernobyl accident at a single reactor unit involved a larger release of these radionuclides
as compared to the Fukushima accident which involved core damage at three units. The reason can be found from the
fact that the Chernobyl had no robust containment, although the containments at the Fukushima plants did not properly
function following core damage partially due to hydrogen explosions.
Another thing to note is that over 100 workers at the Chernobyl plant suffered from acute radiation syndrome as a
result of radiation exposure ranging between 2 to 16 Gy. The residents around the Chernobyl plant also received quite
higher doses than those around the Fukushima, partly because the accident broke out suddenly at Chernobyl but with
some delay (a few hours or days) at Fukushima due to the successful operation of several safety systems in the early
stage. Hence, people could shelter or evacuate at Fukushima.
III. RESULTS AND CONCLUSIONS
The radiological consequences from several major nuclear power plant accidents were compared and some insights
gained from the comparative review. These insights can be used for various applications such as determination of safety
goals for nuclear power plants in terms of radiological consequences as well as the expected likelihood of occurrence,
development of the emergency management program, or performance of Level 3 PSA. However, in doing so, caution is
needed because the actual consequences depend on many factors; for example, power level, containment structure, safety
systems, and plant topology.
TABLE I. Radiological Impacts of Major Accidents (Excerpts from Ref. [1])
Nuclear
Power Plant
Kyshtym
Location
Russia
INES
Level
6
Release of
Radioactivity
100,000 TBq
(¹⁴⁴Ce and ¹⁴⁴Pr: 66%;
⁹⁵Zr and ⁹⁵Nb: 24.9%;
⁹⁰Sr and ⁹⁰Y: 5.4%)
¹³¹I: 740 TBq
Windscale
Pile
UK
5
Three Mile
island
USA
5
Noble gases [mainly 133Xe]:
370,000 TBq;
¹³¹I: 0.55 TBq
Chernobyl
Ukraine
(then
USSR)
7
¹³¹I: 1,760,000 TBq;
137
Cs: 85,000 TBq
Fukushima
Japan
7
¹³¹I: 100,000~500,000 TBq;
137
Cs: 6,000~20,000 TBq
Exposure Dose
Average effective dose of residents:
170 mSv (preceding evacuation);
520 mSv (effective dose equivalent).
Maximum estimated thyroid doses
of residents: 10 mGy (adults);
100 mGy (children).
Maximum effective dose:
40 mSv (emergency worker).
Effective dose of residents
living within 80 km:
0.015 mSv (average);
0.85 mSv (maximum).
Workers with acute radiation
syndrome: < 2.1 Gy (41 people);
2.2~16.0 Gy (93 people).
Average thyroid dose of residents:
138~349 mGy (adults);
449~1548 mGy (children).
Maximum effective dose: 678 mSv
(emergency worker). Maximum thyroid dose:
12 Gy (emergency worker).
Maximum effective dose of residents:
25 mSv (external). Maximum average
thyroid dose of infants in the most
affected district: 80 mGy.
REFERENCES
1.
2.
3.
A. HASEGAWA, K. TANIGAWA, A. OHTSURU, et al., “Health Effects of Radiation and Other Health Problems in the
Aftermath of Nuclear Accidents, with an Emphasis on Fukushima”, Journal of thelancet, 386 (2015).
R. WILSON, “Evacuation Criteria after a Nuclear Accident: A Personal Perspective,” Journal of International DoseResponse Society, 10, 480-499 (2012).
S. JONES, “Windscale and Kyshtym: A Double Anniversary”, Journal of Environmental Radioactivity, 99, 1-6
(2008).
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