Regulatory Approach on Decommissioning of Nuclear Installations in Argentina. Siraky, G.

Transcription

1 Regulatory Approach on Decommissioning of Nuclear Installations in Argentina Siraky, G. Publicado en el 1º Taller CNEA-DOE sobre Desmantelamiento de Instalaciones Nucleares, Buenos Aires, Argentina, mayo 2001

2 REGULATORY APPROACH ON DECOMMISSIONING OF NUCLEAR INSTALLATIONS IN ARGENTINA Gabriela Siraky Autoridad Regulatoria Nuclear (Nuclear Regulatory Authority) Buenos Aires, Argentina 1. INTRODUCTION The Nuclear Regulatory Authority (ARN) is in charge of nuclear activity regulations and control, concerning radiological and nuclear safety, safeguards and physical protection. The ARN is an independent entity within the jurisdiction of the Presidency of the Nation, and has full legal power to act in the fields of public and private rights. The regulatory system applied in Argentina by ARN considers that the owner and operating organization, known as Responsible Organization, is fully responsible for the radiological and nuclear safety of the installation. The regulatory standards are not prescriptive, but, on the contrary they are preformancebased standards, that is to say, they establish the fulfillment of safety objectives. The construction, commissioning, operation or decommissioning of a significant nuclear installation shall not start without the corresponding license issued by the Regulatory Authority. 2. LEGAL FRAMEWORK During the period 1950 to 1994 the National Atomic Energy Commission (CNEA) had, among other areas of competence, the regulatory function in the field of radiological and nuclear safety, particularly on those aspects concerning the human health protection against the harmful effects of ionising radiation, the nuclear installations safety and the control of nuclear material use. In 1994 the Executive Power transferred the Authority for regulation of nuclear activities from the Regulatory Branch of CNEA to the National Board on Nuclear Regulation (ENREN) through the Decree No 1540/94. This decree also created a state company (Nucleoeléctrica Argentina SA, NASA, owner of the nuclear power plants), with the aim of privatising their activities in the near future. The decree established that CNEA would even continue as a research and development institution. In April 1997, Act No 24804; National Law of Nuclear Activity [1] was passed, proclaiming (in its Article 7) the creation of the Nuclear Regulatory Authority (ARN). This authority is in charge of nuclear activity regulations and control concerning radiological and nuclear safety, safeguards and physical protection, giving, in addition, advice to the Executive Power on subjects of its competence. The resources and technical personnel of ARN arose from from the former ENREN and from the regulatory branch of the National Commission of Atomic Energy, and its structure was adapted to the mandate. The Regulatory Authority has a highly competent

3 technical personnel (180 professionals and technicians), endowed with a large experience in the radiological protection and nuclear safety fields. A great portion of this personnel has had the opportunity to pass their knowledge gained throughout years of application in an annual Post-graduated Course on Radiological and Nuclear Safety, under the auspices of the International Atomic Energy Agency, since the early eighties. The Act N establishes also that CNEA is responsible for determining the decommissioning of nuclear power plants and any significative radioactive facility. 3. REGULATORY FRAMEWORK Act No empowers the Regulatory Body to establish standards, with the aim to regulate and to control nuclear activities, of application along the whole national territory. The first regulatory standards were initially produced some 20 years ago. In the course of time a normative system was established comprising subjects such as radiological and nuclear safety, safeguard of nuclear materials and physical protection. The system, known as AR Standards (AR meaning Autoridad Regulatoria - Regulatory Authority), has at present 55 standards. The regulatory standards are based on a set of fundamental concepts, which are part of the philosophy sustained by the regulatory system concerning radiological and nuclear safety, safeguard and physical protection. Such concepts, are the following: Basic criteria of radiological and nuclear safety: The basic criteria in which radiological and nuclear safety is supported are being applied since long time ago and they are in agreement with the ICRP recommendations (in its publications No. 26, [3] No. 60 [4] and No. 77 [5]). On the other hand, the Regulatory Body has contributed to formulate recommendations issued by international bodies (such as IAEA, ICRP and UNSCEAR), so that it is usual to find, in its own standards, concepts dealing with radiological and nuclear safety that appear in such recommendations. Further, nowadays, ARN is taking part of the IAEA s Advisory Commision on Safety Standards (ACSS), the Nuclear Safety Standards Committee (NUSSC), the Radiation Safety Standards Committee (RASSC), the Waste Safety Standards Committee (WASSAC) and the Transport Safety Standards Advisory Committee (TRANSSAC). Responsibility for safety: The regulatory system considers that the owner and operating organisation, known as Responsible Organisation is responsible for the radiological and nuclear safety of the installation as well as for the physical protection and safeguards of nuclear material in the facility. The mere compliance with the regulatory standards does not exempt the organisation from the mentioned responsibility. For this reason the regulatory standards are not prescriptive but, on the contrary, they are performance-based standards, that is to say, they establish the fulfilment of safety objectives. The way of reaching these objectives is based on engineering experience, on the qualification of designers, constructors and operators and on suitable decisions taken by the Responsible Organisation itself. Therefore, the Responsible Organisation must demonstrate and convince the Regulatory Body that the installation is safe. In this context, this type of workshops and trainning programmes that CNEA are conducting as the Responsible Organisation for decommissioning are welcomed by ARN, in the sense that they are aimed to the qualification of the personnel. 4. LICENSING SYSTEM AND REGULATORY ACTIVITIES The regulatory standards establish a Lisensing System. One of its main requirements is that the construction, commissioning, operation or decommissioning of a significant nuclear installation shall not start without the corresponding licence, required by the Responsible Organisation and issued by the Regulatory Body. The validity of such licences

4 is subordinated to the compliance with stipulated conditions, and to standards and requirements issued by the Regulatory Body. The non-compliance with any of these requirements may be enough reason for the Regulatory Body to suspend or cancel the corresponding licence validity, according to the sanction regime in force. In relation to the regulatory activities, since the early days, the Regulatory Body has performed assessments as well as multiple and different regulatory inspections and audits as frequently as considered necessary, with the purpose of verifying that nuclear installations satisfy the standards, licences and requirements in force. Act No 24804, National Law of Nuclear Activity, authorizes the Regulatory Body to continue with such inspections and regulatory assessments, performed by its personnel as: Routine inspections are essentially carried out by Regulatory Body s inspectors. Their purpose is to verify that the Responsible Organisation complies with limits and conditions of operation established in the operation licence. Non routine inspections are carried out by Regulatory Body's specialists on special subjects. These inspections are performed under special circumstances or due to the occurrence of certain events in the installation. Assessments are performed by Regulatory Body personnel and consist of the analysis of data obtained during an inspection or the analysis of documents demonstrating installation s safety. They may also refer to the evaluation of eventual modifications or improvements to the installations. Audits are performed according to written procedures and are programmed in order to analyse organisation, operation and process aspects related to radiological, nuclear and waste safety. 5. RADIOLOGICAL CRITERIA APPLIED The radiological safety criteria for this stage are similar to those applied to construction or operation, so the several regulatory standards concerning raidological safety in operation are, in general terms, also applicable to decommissioning. The key point to take into account is that the facilities remain under Regulatory Control until the final requirements of the decommissioning are fulfilled (AR ). Therefore, the system of radiological protection established in AR shall be applied (Fig. 1). Clearance levels were not set forth in this standard, due to its objective oriented character. Notwithstanding, the exemption of practices that entails neither effective doses over 10 µsv (for the most exposed individuals) nor effective collective doses beyond 1 man-sievert is established. The release of materials during decommissioning activities shall be proposed by the Responsible Organisation in the Safety Report or the relevant document, required for the issuance of the licence or authorisation. In general terms, the usual radiological practice takes into account the reference levels of surface contamination exposed in Table 2 [3]. 6. APPLICABLE REGULATIONS TO THE DECOMMISSIONING STAGE Four main standards issued by the Regulatory Authority are applicable to the decommissioning stage of nuclear installations in Argentina. One of them is specific and the other three have general requirements for the licensing of nuclear installations and for the radiological or waste safety. They are: 1. Licensing of Relevant Nuclear Installations 1, AR 0.0.1, Rev.1, In the Argentinean standards, Installations are considered as relevant and non-relevant (or minor) in function of the associated risk. Examples of relevant installations: nuclear reactors, large accelerators

5 2. Basic Standard for Radiological Safety, AR , Rev.2, Decommissioning of Nuclear Power Plants, AR , Rev.1, Radioactive waste management, AR , Rev.0, Licensing of Relevant Nuclear Installations The basic concepts of this standard are: A licence issued by the Regulatory Authority is required for the construction, operation and decommissioning stages of an installation life-cycle. A Responsible Organisation (RO) must be identified for each stage of a relevant installation. This RO is responsible for the nuclear and radiological safety of the installation in each of its stages: design, construction, commissioning, operation and decommissioning. The RO must identify a qualified staff member, called Primary Responsible, who is assigned with the direct responsibility for the nuclear and radiological safety of this installation. The Responsible Organisation shall present to the Regulatory Authority, with the precedence that this decides, the technical documents required for the safety assessment, nuclear and radiological, of the installation stage whose licence is applied to Basic Standard for Radiological Safety This standard provides the radiological criteria to be applied for the decommissioning of nuclear facilities. Although this applicability is not explicitly mentioned in the standard, the decommissioning stage is considered a part of an installation life-cycle (according to the AR Standard, and other international recommendations [1],[2]) Decommissioning of Nuclear Power Plants, AR , Rev.1, This standard establishes the general requirements for the decommissioning stage. The main conditions are: The Responsible Organisation, holder of the Decommissioning Licence, is responsible for the planning and provision of the required resources for the safe decommissioning of the nuclear power plant. The Decommissioning Programme shall consider the necessary institutional arrangements and, anticipate the adequate radiological protection in each step. A previous approval by Regulatory Authority is required to implement the Programme. The Decommissioning Programme shall include all the necessary steps for ensuring the adequate radiological protection with the minimal surveillance after the decommissioning. The Responsible Organisation may delegate to perform the decommissioning, either totally or partially, to third parties, but keeping all responsibilities. During the decommissioning process, the Responsible Organisation shall contemplate and put under Regulatory Authority consideration, the following: a) Management of the project b) Site management c) Role and responsibilities of the organisations involved and plants where radioactive materials are processed, used or stored and their inventory is about a given amount.

6 d) Radiation protection e) Quality assurance f) Waste segregation, conditioning, transport and final disposal g) Surveillance after completion of partial stages of decommissioning h) Physical protection i) Safeguards and non-proliferation Commitments If the dismantling is deferred for a significant period of time after the final shutdown decision, the Responsible Organisation shall provide the adequate storage for drawings, reports, data and all the relevant documents for the decommissioning. In this case, the Responsible Organisation shall keep its responsibilities during this period, maintaining in operation all the safety systems required to keep the facility on safe conditions Radioactive waste management, AR , Rev.0, This is the specific standard for waste safety issued by ARN. It is complementary to the standard AR for waste management, and includes a set of criteria fully in accordance with internationally agreed principles, to be applied in the field of waste management Other applicable regulatory standards are: AR AR AR AR Licensing of personnel Occupational Exposure Limitation of Radioactive Effluents Quality assurance REFERENCES [1] Sajaroff, Pedro, Regulatory criteria considered in Argentina for the decommissioning of nuclear installations, presented at IAEA s Technical Committee Meeting on the Development of Regulatory Procedures for the Decommissioning of Nuclear Facilities, Vienna, November [2] INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION Recommendations, ICRP Publication 60, Pergamon Press (1991). [3] IAEA/FAO/ILO/PAHO/WHO, Basic Safety Standards - International Standards for Protection Against Ionising Radiation and for the Safety of Radiation Sources, Safety Series No. 115, IAEA, Vienna (1996). [4] Menossi, C. - Personal communication, 12/96. [5] Plaza, H., Internal Report, 2/95. [6] Ciallella, H. E., Jordán, O.D., Oliveira, A.A., Nollmann, C.E., Radon emanation measurements from uranium ore tailings in Argentina - in Radiation Protection Practice, Proceedings of the 7 th International Congress of the International Commission on Radiological Protection, Sydney (1988). [7] Curti, A. R., Bomben, A.M., Gómez J.C., Oliveira, A.A., Environmental radiological monitoring around uranium mining and milling sites in Argentina - in Proceedings of the 8 th International Congress of the International Commission on Radiological Protection, Montréal (1992). [8] Bomben, A.M., Gómez J.C., Oliveira, A.A., Uranium mining and milling sites in Argentina: Environmental radiological monitoring ( ) - in Proceedings of the 9 th International Congress of the International Commission on Radiological Protection, Vienna (1996).