Ionization Smoke Detectors in Slovenia – Current Status
and Future Challenges
Simona Sučić
ARAO
Celovška cesta 182
SI-1000 Ljubljana, Slovenia
[email protected]
Kostanjevec Marko, Tomaž Žagar
ARAO
Celovška cesta 182
SI-1000 Ljubljana, Slovenia
[email protected], [email protected]
Simon Dekleva
Zarja Elektronika
Polčeva pot 1
SI- 1241 Kamnik, Slovenia
[email protected]
ABSTRACT
Ionization smoke detectors use an ionization chamber and a radionuclide such as
americium-241 to detect smoke. In Slovenia, installation of ionization smoke detectors started
at the beginning of the 1970’s. Due to good technical performance, ionization smoke detectors
were widely used and can be found in industrial, service and even in general public buildings
like hospitals or schools. Significant numbers of ionization smoke detectors are still in use,
however during the last 10 years they are increasingly being replaced by new technologies. In
practice, major reconstructions and upgrades of the existing fire alarm systems usually occur
during the renovation of buildings and in that process old ionization smoke detectors are also
being removed. According to the Slovenian legislation removed detectors are collected and
transmitted to the ARAO - organization responsible for the public service of institutional
radioactive waste management. Due to the large number of ionization smoke detectors, it is
becoming a routine practice in their treatment that the device is disassembled and the associated
radioactive source is recovered and conditioned for storage. The rest of non-radioactive
materials (plastic, metal and electronic components) are treated and prepared for recycling.
After such conditioning the radioactive part of smoke detectors is in more appropriate form for
storage and requires significantly less space in the storage facility. This paper presents current
status and lessons learned related with the conditioning of ionization smoke detectors that were
collected in recent years through the public service in field of institutional radioactive waste
management in Slovenia. Also, future challenges and positive effects of performed actions
related with the conditioning of ionization smoke detectors in Slovenia are discussed.
1006.1
1006.2
1
INTRODUCTION
Smoke detectors used as fire alarms are important safety devices, because of their obvious
potential to save lives and property. The OECD report [1] indicated that around 40 % of fire
related deaths could be prevented by use of smoke detectors. Also, according to [1], the benefits
from the use of ionization smoke detectors are at least 500 times greater than the possible
harmful effects. Ionization smoke detectors are the most common type of smoke detectors and
have been commercially manufactured and used around the world for several decades [2]. Due
to the price and their technical characteristics, mainly very good sensitiveness to a wide range
of fire conditions, they were much more popular than the other types of smoke detectors.
Nowadays, the other types of smoke detectors are improved and it is a common practice that
wherever is possible, both users and manufacturers, are moving towards technologies which do
not require radioactive sources [3]. However, due to better technical performances, ionization
smoke detectors may still be in use in some industrial and service buildings. They are robust
and can survive quite severe conditions without damage [4].
Ionization smoke detector contains radioactive source, which produces ions between two
charged electrodes. Alpha particles from the radioactive source ionize air molecules, allowing
positive and negative ions to flow between charged electrodes in the smoke detector. The smoke
alarm triggers when smoke particles disrupt the constant flow of ions [5]. The majority of smoke
detectors contain an artificially produced radionuclide Am-241. Am-241 is produced in nuclear
reactors and is a decay product of Pu-241. Am-241 is long-lived radionuclide that emits alpha
particles and low energy gamma rays [6]. An older versions of ionization smoke detectors
contained Ra-226, Pu-239, Kr-85, Eu-152 etc. It is important to emphasize that the ionization
smoke detectors actually need a small amount of radioactive material with low activity (a few
kBq) to ionize the air around the detector and that the dose rate at the detector housing is usually
several times higher than the dose rate due to natural background radiation. However, with the
distance, the dose rate decreases rapidly [6].
Being mainly composed of an americium source (< 40 kBq), ionization smoke detectors
do not present a health risk for people who are working in buildings or other premises on which
they are installed. Operational practice confirmed that there was no health threat from ionization
smoke detectors as long as the detector was installed and used properly. However, dealing with
a large number of ionization smoke detectors like maintenance or management of disused
detectors can represent a significant risk and thus require safe management [3]. Ionization
smoke detector is considered as sealed radioactive source. The Radiation Protection Safety and
Safety of Radiation Sources: International Basic Safety Standards [2] defines a sealed source
as “radioactive source in which the radioactive material is (a) permanently sealed in a capsule
or (b) closely bounded and in a solid form”. When a source is no longer needed or becomes
unfit for use in its application, it is considered disused. Disused sources, if they are deemed
unusable, are conditioned and disposed of at a waste disposal facility, if such a facility is
available. If a disposal option is not in place the conditioned disused source should be stored
under proper conditions [3].
In many countries individual smoke detectors are exempted from regulatory control due
to the extremely small amount of radioactive material, therefore, disposal in municipal landfills
is often considered as appropriate and allowed. However, due to the large number of these
devices and the long half-life of the sources, it is becoming a routine practice worldwide to
collect them, remove and consolidate the sources, and condition for long term storage. The rest
of non-radioactive materials (plastic, metal and electronic components) are treated and prepared
for recycling. This is a typical activity that is performed in many countries in order to minimize
the volume of waste stored in the storage facility. Additionally, in many countries there is a
Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016
1006.3
limiting concentration of 4,000 Bq/g for alpha emitters in individual radioactive waste packages
for disposal into shallow ground repositories. Also, many countries have opted for removing
the old and unused ionization smoke detectors from the public domain and have treated, and
stored them in centralized facilities [7]. Conditioning, according to the IAEA Safety Glossary
[8], includes operations that produce a waste package suitable for handling, transport, storage
and/or disposal. Retrievability for further processing and disposal is recommended by
international recommendations [3]. Governmental bodies are preforming many activities in
order to minimize possibilities that ionization smoke detectors will be lost, stolen, or improperly
discarded. A specific concern in management of ionization smoke detectors is to ensure that
devices are properly treated and stored after they are no longer in use. This requires tracking of
a device during its entire life cycle. The Code of Conduct [9] calls national regulatory bodies
for establishing and maintaining a national register of certain sealed radioactive sources. This
register should include the category of radioactive source, the serial number, manufacturer’s
type number, radionuclide, activity, physical form, location of source, the purpose of use, the
licence holder or user, details of receipt or transfer or disposal of the source.
“CRADLE-TO-GRAVE” CONTROL OVER IONIZATION SMOKE
DETECTORS IN SLOVENIA
2
In Slovenia, installation of ionization smoke detectors started at the beginning of the
1970’s. Due to good technical performance, ionization smoke detectors were widely used and
can be found in industrial, service and even in general public buildings like hospitals or schools.
According to Slovenian regulations, special permits for the use of ionization smoke
detectors are not required. However, the users or owners of smoke detectors have certain
obligations and must fulfill prescribed requirements. For example, registration or notification
of the Slovenian Nuclear Safety Administration (SNSA) who keeps the national register of
radioactive sources is required. The notifications for any further changes in the number of
smoke detectors, changes of their locations or changes of ownership are also required. Users of
smoke detectors shall ensure reviews of smoke detectors by an authorized radiation protection
expert every five years. Companies engaged in servicing and maintenance of ionization smoke
detectors must be authorized for dealing with radioactive sources. At the end of the smoke
detector’s lifetime, the user have three months to ensure the transfer to the Central Storage
Facility. By the national strategy and regulations there is also an option to transfer disused
smoke detectors abroad for recycling or to return them to the manufacturer/supplier. Within the
eight days after the ionization smoke detectors were transferred, the new owner must inform
the SNSA and prove ownership and responsibility. Described notification system is designed
in order to control the usage of ionization smoke detectors and to prevent any undesired
situations or loses.
2.1
Types and Quantities of Ionization Smoke Detectors in Slovenia
The users and maintainers of ionizing smoke detectors in Slovenia are usually well
informed about the necessary steps that must be performed when old ionizing smoke detectors
are being replaced or removed. Removed units are usually stored in bags or boxes before being
sent to the ARAO. According to the register [10] of accepted ionization smoke detectors into
Central Storage Facility, the most commonly used radioactive source in Slovenian ionization
smoke detectors is Am-241. Rarely ionization smoke detectors contained Ra-226 and just few
detectors contained Pu-239. As presented in Table 1, waste management practice revealed that
36 models of ionization smoke detectors, produced by 16 different manufacturers are present
in Slovenia.
Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016
1006.4
Table 1: Types of ionization smoke detectors discovered in Slovenia [10]
Manufacturer
Model
APOLLO
S60, S30, S90, XP-95
Radionuclide
Activity
Origin Country
United
Kingdom
Am-241
33 kBq
Am-241
30 kBq
Am-241
Am-241
Am-241,
Ra-226
30 kBq
555 kBq
2.7 MBq,
1.3 MBq
ST-I-DA
Am-241
33 kBq
IJD-5
LKM-1978, LKM-1979
I-716, F 716
Am-241
Am-241
Am-241
74 kBq
5 kBq*
30 kBq
United
Kingdom
USA
Germany
Slovenia
JD-1S
Am-241
207 kBq
Serbia
MORLEY IAE
MI-ISE
Am-241
18.5 kBq
PASTOR
SIEMENS
STATITROL
SYSTEM SENSOR
SLAVIJAELEKTRO
TAL (TEHNO
ALARM)
IOJ-1
BR 910
301G7
1412
SV-1
Am-241
Am-241
Am-241
Am-241
Am-241
33 kBq
30 kBq
33 kBq
37 kBq
207 kBq
United
Kingdom
Croatia
Germany
USA
USA
Serbia
IDD-801, IDD-801N
Am-241
74 kBq
Croatia
TDZ DELČEVO
IDD 801, IDD 801S,
IDD 802, IDD 803
RID-1
Am-241
74 kBq
Macedonia
37 MBq
USSR
CERBERUS
F 716, F 716I,
F 715V, F 716VI,
F 712
F 910, F 906, F 911
F 600, F 6A Ex
FES 5B, FES 5.220B
CALECTRO,
NITTAN
ERA
ESSER
ISKRA
INSTITUT “BORIS
KIDRIČ” - VINČA
Unknown
238
Pu, 239Pu
Switzerland
*The activity does not exceed regulatory limits for exemption levels in Slovenia
From year 2009 until the end of 2015 more than 18,000 of ionization smoke detectors
were accepted for conditioning and storage. Before that around 10,000 of ionization smoke
detectors were stored in the Central Storage Facility. The most frequent models that were
accepted in Central Storage Facility are F 716, FES 5B (Cerberus) and IDD 801 (TZD Delčevo).
The diversity and share of major producers in total amount of detectors that were in use in
Slovenia are given in Figure 1. In addition to ionizing smoke detectors already accepted in the
Central Storage Facility, it is expected that in the scope of the public service at least 2,000
detectors annually will be collected within next 10 years. According to the national registry of
radiation sources [11], at the end of 2015 24,330 ionisation smoke detectors are still being used
by 285 organisations around Slovenia. Unfortunately, it is assumed that there is also a certain
amount of detectors in use which is not yet registered in national registry of radiation sources
Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016
1006.5
operated by SNSA. One of the reasons is that the application of smoke detectors started many
years before the regulatory framework and national register were established.
8%
2% 1%
8%
Cerberus
Delčevo
Apollo
26%
55%
Iskra
Statitrol
Other
Figure 1: Diversity and share of major producers in total amount of ionization smoke
detectors that were in use in Slovenia [10]
2.2
Management of Disused Ionization Smoke Detectors
During major reconstructions or upgrades of the existing fire alarm systems old ionization
smoke detectors are being removed. These activities are usual linked with the renovation or
major adaptation of buildings. According to Slovenian regulations, only licenced organisation
for dealing with radioactive sources can perform these activities.
Collection
Once being in possession of removed ionization smoke detectors the user/owner notifies
ARAO for further steps in the process of waste management. ARAO provides collecting,
transportation, handling, conditioning and storage services for disused sources from various
applications in Slovenia (Figure 2). Also, after the change of ownership ARAO is legally
responsible for the safe and secure conditioning and storage of the sources under its ownership,
and operates under license conditions defined by a regulatory body.
Figure 2: Removed ionization smoke detectors
Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016
1006.6
Storage and Disposal
The first step in the waste management process is characterization of waste or disused
sealed sources where the activity, the radionuclide content and other important characteristics
of waste are being determined. The disused ionization smoke detectors are sorted and grouped
based on the management option (conditioned, unconditioned), and by characteristics of the
source (radionuclides). ARAO temporary store disused smoke detectors in the Central Storage
Facility and prepare them for further conditioning. As required by the regulatory body, ARAO
maintains an up to date inventory of all radioactive sources in its possession. If it will not be
possible to send disused sources abroad for recycling the only sustainable and long term option
will be disposal which is the final phase in the life cycle of radioactive sources. Prior to final
disposal safety analysis needs to be performed. However, since the final disposal facility in
Slovenia is not available conditioned radioactive sources from ionization smoke detectors for
certain amount of time will be stored in the Central Storage Facility. When the disposal facility
will be available radioactive sources will be once again conditioned to meet waste acceptance
disposal criteria and finally disposed.
Conditioning
Up to now ARAO accepted more than 28,000 units of disused ionization smoke detectors
into Central Storage Facility. This large number of unconditioned smoke detectors represents a
volume of approximately 30 m3 which could be problematic from the aspect of fire safety
(plastic material), occupancy of storage space, source leaking, degradation of source housings
etc. Before starting the detectors dismantling and radioactive source recovery activities detail
inventory of smoke detectors stored in the facility was revised and updated. The next step is the
removal of the sources from the original devices (Figure 3).
Figure 3: Removal of the radioactive sources from the original devices (dismantling)
Performed activities resulted in a huge reduction of the volume of packages intended for
storage or disposal. According to the ARAO experiences during conditioning of smoke
detectors in last four years the original volume of waste packages was reduced by factor 25.
Over 12,000 units of ionisation smoke detectors with the radionuclide Am-241 were
conditioned. As seen in Figure 4 the sources removed from smoke detectors have been packed
in polyethylene bags, which are then transferred into the standard steel 210 liter drums.
Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016
1006.7
Figure 4: The sources removed from smoke detectors packaged in polyethylene bags and
loaded in the standard steel 210 liter drum
Operational experienced confirmed that more than 6,000 sources can be stored in one
drum and that for storage purposes additional shielding of drums is not necessary. Contaminated
equipment (smear, gloves, etc.) represents a very small proportion of the secondary radioactive
waste, which is practically negligible. Operations of removing sources from devices involves
the manipulation of bare sources, which needs special procedure, shielded and ventilated
workplace and tools to protect the operators and prevent the spread of contamination. Ionization
smoke detectors were handled manually by trained and skilled operators (Figure 5). The
radioactive sources and contaminated housing of smoke detectors packed in steel drums have
been safely stored in the Central Storage Facility. The rest of non-radioactive materials (plastic,
metal and electronic components) are treated and prepared for recycling. After such
conditioning the radioactive sources from smoke detectors are in more appropriate and safe
form for storage and require significantly less space in the storage facility. After the storage in
the Central Storage Facility, it is likely that the internal bags and drums will be retrieved for
further conditioning and repackaging prior to disposal. All handling operations were carefully
planned, tested and implemented in coordination with the radiation protection staff.
Figure 5: The radioactive sources of smoke detectors safely store in the Central Storage
Facility
3
BENEFITS AND LESSONS LEARNED
Operational experiences confirmed that conditioning of ionization smoke detectors and
separation of radioactive from non-radioactive part is an effective method for volume reduction.
During conditioning activities a lot of plastic materials related with the ionization smoke
detectors were removed from the storage facility. This represents an additional operational
safety benefit and reduction of potential fire hazard.
The IAEA technical manual [7] and international catalogue of sealed radioactive sources
and devices [12] and many other manually obtained data (design data, photos, illustrations etc.)
Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016
1006.8
from manufactures/maintainers of devices were very helpful during the preparation of
dismantling operations.
However, dealing with disused ionization smoke detectors requires different types of
precaution measures to be taken in order to prevent mechanical damages of the radioactive
source (e.g. dropping from a height). Damaged devices must be separately collected and treated
to avoid cross contamination. Dismantling of smoke detectors must be carried out slowly and
carefully to preserve the radioactive source intact and to protect spreading of contamination to
non-radioactive part of device. Sources may also be leaking, which would require specific
radiation safety measures.
Conditioning of smoke detectors has become a regular activity and an integral part of the
core mission of ARAO. Operations were carefully planned and carried out by ARAO staff
exclusively. During the performed activities existing knowledge is upgraded and ARAO staff
is now able to dismantle all types of detectors that are in use in Slovenia.
4
CONCLUSION
The paper provides a review of management practices related with the treatment of
ionization smoke detectors in Slovenia. Presented management practices are fully in line with
the sustainability policy and the mission of ARAO. Operational experiences confirmed that
performed activities were the most cost effective way to improve the safety and security of the
long lived sources and minimize the volume of waste in the Central Storage Facility. All
activities were performed according to national requirements and international standards.
Although the special attention was given to the international recommendations for reuse or
recycling of disused sources [3], it is very unlikely that anyone would want to take radioactive
sources from smoke detectors for any further use. The obtained results clearly confirmed the
importance of well trained and skilled staff with a potential to cope with the most demanding
aspects of waste management. In this sense additional efforts in the near future should be
designated for the conditioning of sources to meet the waste acceptance criteria of the future
disposal facility.
REFERENCES
[1]
Organisation for Economic Co-operation and Development, Nuclear Energy Agency,
“Recommendations for Ionization Chamber Smoke Detectors in Implementation of
Radiation Protection Standards”, OECD NEA, 1977.
[2]
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Sources: International Basic Safety Standards - Interim Edition General Safety
Requirements Part 3, IAEA Safety Standards Series No. GSR Part 3 (Interim), IAEA,
Vienna, 2011.
[3]
International Atomic Energy Agency, Management of Disused Sealed Radioactive
Sources, IAEA Nuclear Energy Series No. NW-T-1.3, Vienna, 2014.
[4]
M. W. Carter, “Domestic Smoke Detectors – A Radioactive waste problem?”,
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Protection Association, 1996, V3-119.
[5]
IQ8Quad, ESSER by Honeywell, “Pravi senzor za vsako okolje - Principi zaznavanja
javljalnika IQ8Quad”, Dunaj, 2009.
Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016
1006.9
[6]
World Nuclear Association, “Smoke Detectors and Americium”, Retrieved from URL:
http://www.world-nuclear.org/information-library/non-power-nuclearapplications/radioisotopes-research/smoke-detectors-and-americium.aspx, 9. August
2016.
[7]
International Atomic Energy Agency, “Draft Technical Manual on: Dismantling of
Ionic Smoke Detectors and Conditioning of associated radioactive sources”, IAEA,
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[8]
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Proceedings of the International Conference Nuclear Energy for New Europe, Portorož, Slovenia, September 5-8, 2016