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21
Criteria for Environmental Rehabilitation of the Temporary Storage Site for Spent Nuclear Fuel and Radioactive Waste in Gremikha Village*
Yu. Ye. Gorlinsky, V. A. Kutkov, and N. K. Shandala, Russian Research Center—Kurchatov Institute
To ensure radiation safety for personnel and the public during the conversion and environmental rehabilitation of the temporary storage site for spent nuclear fuel and radioactive waste in Gremikha village, a radiation safety strategy must be in place that, if followed, would define the following:
Radiation protection criteria for the planning of work
Radiation protection criteria for the conduct of work
Criteria for assessing radiation safety status during the conduct of planned work and at its completion
The regulatory documents in effect in the Russian Federation consider the following two categories of ionizing radiation sources as subject to radiation safety regulation:1
*
Translated from the Russian by Kelly Robbins.
1
Kutkov, V. A., B. A. Bezrukov, V. V. Tkachenko, V. P. Romanov, I. V. Dolzhenkov, V. N. Lebedev, and V. I. Petrov. 2002. Fundamental principles and requirements of regulatory documents in the practice of ensuring radiation safety at nuclear power plants: A training handbook. V. A. Kutkov and B. A. Bezrukov, ed. Moscow: Rosenergoatom, 292 pp.
Radiation safety norms (RSN-99): Hygiene regulations SP-2.6.1.758-99. 1999. Moscow: Ministry of Health of the Russian Federation.
Basic sanitary rules for ensuring radiation safety of personnel and the population (BSRERS-99): Sanitary rules SP-2.6.1.799-99. 2000. Moscow: Ministry of Health of the Russian Federation.
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Technogenic radiation sources specially created for their useful application or sources that are by-products of such activity
Natural radiation sources covered by the Radiation Safety Norms and Rules
In using the term ionizing radiation source or simply source, we follow the common practice in radiation protection and safety by which source means a radioactive substance or device emitting or capable of emitting ionizing radiation and covered by the Norms and Rules.2 Everything that could cause irradiation during emission of ionizing radiation or discharge of radioactive substances or materials is considered to be a source. For example, substances that emit radon are sources that exist in the environment, a gamma-radiation sterilization device is a source used in practical operations to preserve food products, and a nuclear power plant is a source in practical operation to produce electricity using nuclear energy. In the application of the Norms and Rules, complex devices or several devices located in one place or at one site may under appropriate circumstances be considered as a single source. In providing radiation protection for people and ensuring their safety, any source is considered as a source of harm and danger. The harmfulness of a source is determined by the real level of radiation associated with it. The danger is determined by the potential exposure that might result if the source goes out of control and leads to an accidental irradiation capable of having substantial radiation effects.3
The foundation for ensuring radiation safety for operations involving technogenic sources is the licensing of such activities, which entails the presence of a license holder, a legal entity bearing full responsibility for operations involving the technogenic source. As a rule, such a source is created for a purpose in the form of a device or unit that makes the most effective use of the ionizing radiation created; therefore, such a source is fundamentally a radiation hazard. The regulatory requirements applied to operations involving a technogenic source are primarily aimed at ensuring that such a specially created source is managed to prevent it from going out of regulated control.4 In this regard, the results of
2
International basic safety standards for protection against ionizing radiation and for the safety of radiation sources: Safety series No. 115. 1996. Vienna: International Atomic Energy Agency (Russian edition, 1997).
3
Kutkov, V. A., B. A. Bezrukov, V. V. Tkachenko, V. P. Romanov, I. V. Dolzhenkov, V. N. Lebedev, and V. I. Petrov. 2002. Fundamental principles and requirements of regulatory documents in the practice of ensuring radiation safety at nuclear power plants: A training handbook. V. A. Kutkov and B. A. Bezrukov, eds. Moscow: Rosenergoatom, 292 pp.
Kutkov, V. A., V. V. Tkachenko, and V. P. Romantsov. 2003. Radiation safety for nuclear power plant personnel: A training handbook. 2003. V. A. Kutkov, ed. Moscow-Obninsk: Atomtekhenergo and Obninsk State Technical University for Nuclear Power Engineering, 344 pp.
4
Op. cit.
Kutkov, V., O. Kochetkov, and A. Panfilov. 2002. Strategy of control at source as a base for protecting workers against risks arising from exposure to ionizing radiation in the Russian Federation.
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dosimetric monitoring of radiation exposure of the public and personnel from the device in question are an indicator of its safe status.5
The main characteristic of natural ionizing radiation sources is the degree of harmfulness associated with them. Their effect on humans is of a prolonged nature, extended over time. In view of the low specific activity of radioactive materials that the Norms and Rules place in this source category, even if they should go out of control they are incapable of producing substantial doses from accidental exposure.6
In considering radiation sources of these two types, the system for regulation of radiation safety formulates its requirements for operations involving them depending on their characteristic danger-harm ratio. For example, annual public exposure from potentially dangerous technogenic radiation sources is limited to a maximum dose of 1 mSv per year, while the total exposure from natural sources for the same period is deemed acceptable if it does not exceed 5 mSv per year. In addition, such exposure is considered as an addition to the existing natural background radiation, the dose from which, as a rule, ranges from 2.5 to 10 mSv per year.7
There is also a third type of source along with the sources noted above: radioactive contamination dispersed in the environment as a result of practical activities that have already terminated. As a rule, the individuals or entities responsible for such contamination are not to be found, while the sources themselves are part of the “radiation legacy.” Among other aspects, exposure of the affected population and personnel linked with the radiation legacy includes
exposure from global radionuclide fallout resulting from nuclear weapons tests, and
exposure at contaminated sites of decommissioned military facilities that currently fail to meet requirements applied to civilian radiation-hazard facilities.
In Occupational radiation protection: Protecting workers against exposure to ionizing radiation. Proceedings of an international conference, Geneva, August 26-30, 2002. Vienna: International Atomic Energy Agency, pp. 39-44. Available online at www-pub.iaea.org/MTCD/publications/PDF/Pub1145_web.pdf. Accessed August 16, 2007.
5
Op. cit.
6
Radiation safety norms (RSN-99): Hygiene regulations SP-2.6.1.758-99. 1999. Moscow: Ministry of Health of the Russian Federation.
Basic sanitary rules for ensuring radiation safety of personnel and the population (BSRERS-99): Sanitary rules SP-2.6.1.799-99. 2000. Moscow: Ministry of Health of the Russian Federation.
7
United Nations Scientific Committee on the Effects of Atomic Radiation. 2000. Sources and effects of ionizing radiation: 2000 report to the General Assembly with scientific annexes. Volume 2: Effects, Annex B: Exposure from natural radiation sources. New York: United Nations. Available online at www.unscear.org/unscear/en/publications/2000_2.html. Accessed August 16, 2007.
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Exposure from such sources is not regulated, yet the sources themselves represent a burden of which we must rid ourselves. Key problems of ensuring radiation safety while eliminating the radiation legacy of the former USSR currently remain unresolved. This circumstance has a substantial effect on the evaluation of the acceptability of a number of end states for sites and facilities under environmental rehabilitation. The fact that there are radiation sources that do not fall within the scope of the domestic regulatory base and that are unregulated is a problem for ensuring radiation safety while eliminating the radiation legacy, a problem that cannot go unresolved.8
Limiting the impact of the radiation legacy on the population is not a new problem.9 The International Commission on Radiological Protection (ICRP) devoted a special publication to this problem,10 and the recommendations it contained formed the basis for a safety guide issued by the International Atomic Energy Agency (IAEA) in 2006.11
In the near future, plans call for the release of new ICRP recommendations and subsequently new IAEA regulations. It is expected that their introduction at the national level will be complete by 2015.12 Thus, the time period for the conversion of the Gremikha temporary storage site facilities will coincide with the period during which the new regulatory base for radiation safety will be put into practice. One aspect of the new ICRP recommendations that could have a substantial impact on ensuring radiation safety during the decommissioning of the
8
Sivintsev, Yu. V., V. L. Vysotsky, R. I. Kalinin, V. G. Aden, and A. P. Vasiliev. 2006. Quantitative criteria for rehabilitating the territories of shore technical bases. Atomic Energy, vol. 101, 1st edition, pp. 35-49.
Bylkin, B. K., Yu. Ye. Gorlinsky, V. A. Kutkov, O. A. Nikolsky, V. I. Pavlenko, Yu. V. Sivintsev, and B. S. Stepennov. 2007. Application of multifactor analysis in the selection of end state options and environmental rehabilitation strategies for the temporary storage site for spent nuclear fuel and radioactive waste in Gremikha village. Preprint IAE-6456/3. Moscow: Russian Research Center—Kurchatov Institute.
Shandala, N. K., M. F. Kiselev, M. K. Sneve, et al. 2006. Radiation ecology regulation under conditions of rehabilitation work at SevRAO. Pp. 184-186 in Modern problems of ensuring public radiation safety: Proceedings of a scientific and practical conference, St. Petersburg, December 4-7, 2006. St. Petersburg: Federal Monitoring Service for the Protection of Consumer Rights and Human Welfare.
9
Moiseev, A. A. 1985. Cesium-137, the environment, and man. Moscow: Energoatomizdat.
Marei, A. N., R. M. Barkhudarov, and N. Ya. Novikova. 1974. Global cesium-137 fallout and man. Moscow: Atomizdat.
10
Protection of the public in situations of prolonged radiation exposure: ICRP publication 82. 1999. Annals of the ICRP 29(1-2). Oxford: Pergamon Press.
Gonzalez, Abel J. 2001. Decision-making about chronic radiation exposure to the public: New recommendations from the ICRP. ANRI Magazine 3(26):37-49. Available online at www2000.irpa.net/irpa10/cdrom/01257.pdf. Accessed August 17, 2007.
11
Release of sites from regulatory control on termination of practices safety guide. Safety standards series No. WS-G-5.1. 2006. Vienna: International Atomic Energy Agency. Available online at www-pub.iaea.org/MTCD/publications/PDF/Pub1244_web.pdf. Accessed August 17, 2007.
12
Kutkov, V. A. 2007. Evolution of the system for ensuring radiation safety in light of the new ICRP and IAEA recommendations. ANRI Magazine 1(48):2-24.
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Gremikha facilities and the environmental rehabilitation of the site where they are located include the identification by the commission of three radiation exposure situations requiring various radiation safety approaches:
Planned radiation exposure situations including situations of exposure under controlled conditions involving radiation sources
Accidental radiation exposure situations including situations of uncontrolled exposure from sources that had been under regulated control but went out of control as a result of radiation accidents
Existing radiation exposure situations including situations of exposure from unregulated sources dispersed in the environment and already existing when it was decided that they needed to be controlled. These situations would include both exposure to natural radionuclides found in the environment and contamination from radiation accidents and past activities that occurred as a result of operations with sources that were not under regulated control. Examples of such situations would be exposure caused by the radiation legacy, including, among other things, exposure at contaminated sites of former military facilities located outside the regulatory system and as a result of conversion of those sites now being placed under regulatory control.
In situations of planned exposure, the ICRP uses several approaches to ensuring radiation safety, applying the concepts of dose limit, dose constraint, and reference level.
The dose limit is the level associated with a particular person that represents the maximum individual exposure from all regulated sources. This level is used for retrospective assessment of past exposure occurring within the framework of planned activities. It is also used to demonstrate that a regulated source is being operated in accordance with regulatory requirements. The main area in which this level is used is for radiation regulation in general and radiation safety status for source utilization in particular. The goal of its use is to restrict actual exposure and to provide feedback on how a device is managed and used.13 The level of the dose limit is expressed in normative values, specifically in annual effective dose units.
The dose constraint is the level associated with a particular radiation source and represents the limit on exposure to any individual from this source. This level is used in planning source operations to limit future exposure. The main area in which this level is used is in the optimization of radiation protection overall and the creation of new sources or reconstruction of existing ones in particular. The goal of its use is to limit potential exposure and manage the source. The value
13
Kutkov, V. A., V. V. Tkachenko, and V. P. Romantsov. 2003. Radiation safety for nuclear power plant personnel: A training handbook. 2003. V. A. Kutkov, ed. Moscow-Obninsk: Atomtekhenergo and Obninsk State Technical University for Nuclear Power Engineering, 344 pp.
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BOX 21-1
System of Individual Protection Levels for Job-Related Exposure and Exposure of Members of the Public
Dose constraint and reference level: limitation on future exposure to ensure radiation safety during planning (optimization) or conduct of a regulated practice and/or exposure from a particular regulated source in any sort of planned exposure situation
Dose limit: assessment of radiation safety status based on the level of past (completed) exposure from all regulated sources in a planned exposure situation
of the dose constraint is expressed in terms of normative values, specifically in annual effective dose units.
The reference level is the value established for limiting ongoing human exposure in situations involving accidental or existing exposure as well as during planned activities. If the reference level is exceeded, certain previously planned corrective (protective) actions must be taken to reduce the risk associated with the actual exposure. The goal of its use is to ensure that the dose limit or the levels associated with the dose constraint are not exceeded. The values of the reference levels may be expressed in terms of normative and operational values as well as in terms of activity of the source or of the radioactive contamination in the environment.
The three-component structure of levels for the regulation of radiation protection presented in Box 21-1 corresponds overall with the system that has been created in Russia. Here the role of the dose constraint is played by the quota, “that part of the dose limit established to limit public exposure to a specific technogenic radiation source and means of exposure (externally, by ingestion of water or food, or by inhalation).”14 Although the quota and the dose constraint are similar, they are not essentially equivalent.
On the whole, researchers currently see no substantial impact by the Gremikha temporary storage site on adjoining areas in the observation zone (the settlements of Ostrovnoi and Gremikha). However, the situation might change as a result of rehabilitation efforts.15 Table 21-1 presents a list of end-state options at the temporary storage site after rehabilitation as well as strategies for achieving
14
Radiation safety norms (RSN-99): Hygiene regulations SP-2.6.1.758-99. 1999. Moscow: Ministry of Health of the Russian Federation.
15
Kutkov, V. A. 2007. Evolution of the system for ensuring radiation safety in light of the new ICRP and IAEA recommendations. ANRI Magazine 1(48):2-24.
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them.16 Situations related to exposure during conversion of the storage site and implementation of reprofiling strategies (S4.1, S4.2) or elimination of its facilities (S5.1, S5.2) may be categorized as three different types:
Planned exposure situations caused by work associated with restoration of regulated control over dangerous nuclear and radioactive materials
Planned exposure situations caused by the operation of the facility after its reprofiling as part of implementation of strategies S4.1 and S4.2
Existing exposure situations caused by remaining radioactive contamination at the location of a new radiation-hazard facility as part of implementation of strategies S4.1 and S4.2 or at the location of a new industrial facility as part of implementation of strategies S5.1 and S5.2
In accordance with the new ICRP recommendations for planning radiation protection measures for personnel during the facility conversion and rehabilitation stage, it would be expedient to establish two levels of dose constraints:
For planning routine work, the dose constraint could be set at a level no higher than 5 mSv per year.17
For planning extraordinary work, the dose constraint could be set at a level no higher than 25 mSv per operation.18
To evaluate radiation safety status, it would be appropriate to use the two dose-limit values for exposure from technogenic sources that are currently in RSN-99:
Personnel exposure from all sources during performance of routine work at the facilities: 20 mSv per year on average over any 5 consecutive years, but no more than 50 mSv in any single year
16
Bylkin, B. K., Yu. Ye. Gorlinsky, V. A. Kutkov, O. A. Nikolsky, V. I. Pavlenko, Yu. V. Sivintsev, and B. S. Stepennov. 2007. Application of multifactor analysis in the selection of end state options and environmental rehabilitation strategies for the temporary storage site for spent nuclear fuel and radioactive waste in Gremikha village. Preprint IAE-6456/3. Moscow: Russian Research Center—Kurchatov Institute.
17
Kutkov, V. A. 2007. Evolution of the system for ensuring radiation safety in light of the new ICRP and IAEA recommendations. ANRI Magazine 1(48):2-24.
18
Op. cit.
Bylkin, B. K., Yu. Ye. Gorlinsky, V. A. Kutkov, O. A. Nikolsky, V. I. Pavlenko, Yu. V. Sivintsev, and B. S. Stepennov. 2007. Application of multifactor analysis in the selection of end state options and environmental rehabilitation strategies for the temporary storage site for spent nuclear fuel and radioactive waste in Gremikha village. Preprint IAE-6456/3. Moscow: Russian Research Center—Kurchatov Institute.
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TABLE 21-1 Environmental Rehabilitation Strategies for Facilities at the Temporary Storage Site for Spent Nuclear Fuel and Radioactive Waste in Gremikha Village
End State
Requirements for Safety Level
Strategy
E0: Current state
Full compliance with requirements for nuclear- and radiation-hazard facilities and for placement and operation of storage or burial site for spent nuclear fuel and radioactive waste
S1: No measures taken
E1: Repository for spent nuclear fuel and radioactive waste and/or burial point for secondary radioactive waste
S2: Conversion and temporary operation of facility
S3: Conversion and decommissioning of facility at site
E2.1: Brown field—site for radiation-hazard facility
Full compliance with requirements for radiation-hazard facilities
S4.1: Reprofiling of facility
S4.2: Reprofiling of facility
E2.2: Brown field—site for industrial (nonradiation-hazard) facility
Exemption from regulatory control due to limits on site use
S5.1: Elimination of facility and rehabilitation of site
S5.2: Elimination of facility and rehabilitation of site
E3: Green field
Complete exemption from regulatory control
S6.1: Elimination of facility and renovation of site
S6.2: Elimination of facility and renovation of site
Public exposure from sources associated with the facility: 1 mSv per year on average over any 5 consecutive years, but no more than 5 mSv in any single year
Under the new ICRP recommendations, facility rehabilitation goals may be considered achieved if exposure doses from the remaining contamination do not exceed reference levels established by the national regulatory agency. Their values may be appropriately established depending on the end stage of the facility after the Gremikha temporary storage site has been rehabilitated:19
19
Bylkin, B. K., Yu. Ye. Gorlinsky, V. A. Kutkov, O. A. Nikolsky, V. I. Pavlenko, Yu. V. Sivintsev, and B. S. Stepennov. 2007. Application of multifactor analysis in the selection of end state options and environmental rehabilitation strategies for the temporary storage site for spent nuclear fuel and radioactive waste in Gremikha village. Preprint IAE-6456/3. Moscow: Russian Research Center—Kurchatov Institute.
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If the Gremikha storage site is reprofiled and its site and facilities are subsequently used for the creation of a radiation-hazard facility, the following reference level values are proposed for doses from the remaining contamination:
At worksites for Group A personnel: 3 mSv per year
At worksites for Group B personnel: 1 mSv per year
For people living in the observation zone: 0.1 mSv per year
If the strategy for eliminating the Gremikha storage site is implemented (S5.1 and S5.2) and the site is subsequently used for a general industrial facility, the following reference level values are proposed for doses from the remaining contamination:
For personnel at the industrial facility: 1 mSv per year (0.9 mSv per year as a result of work at the site and 0.1 mSv per year due to living in the observation zone)
For people living in the observation zone: 0.1 mSv per year
If the option for further use of the Gremikha storage site as a radiation-hazard facility is implemented, the design of such a facility and its operations must ensure that annual exposure doses resulting from the activities of the facility do not exceed established dose constraint levels:
For Group A personnel: 7 mSv per year
For Group B personnel: 1 mSv per year
For people living in the observation zone: 0.15 mSv per year
During the stage of planning work and designing radiation protection measures, a final decision must be made on the values of the above-mentioned regulatory levels, with interested parties to be involved in the decision-making process in accordance with the new ICRP recommendations.
