SCK CEN Stress Test. SCK CEN Boeretang 200 BE-2400 Mol. Methodology Report. F. Vermeersch & B. Martens. December 15, 2011

Transcription

1 SCK CEN Stress Test Methodology Report F. Vermeersch & B. Martens December 15, 2011 SCK CEN Boeretang 200 BE-2400 Mol

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3 Table of Contents 1 Objective Stress test for the nuclear facilities of SCK CEN Introduction Safety objective Defence-in-depth Stress test at SCK CEN Reference studies and timeframe of the stress test Hypothesis General Methodology Progress and actual status of the stress test report SCK CEN facilities examined in the stress test Identification of the safety functions for the different installations Project organisation Organisation Technical scope and detailed methodology Initiating events Earthquake Flooding Bush or forest fire Extreme weather conditions Aircraft crash Other man-made events Computer attacks Loss of safety functions Accident management and emergency response Content of the stress test report Table of contents of the final report SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 1

4 Abbreviations ANS BR1 Advanced Nuclear Systems Institute Belgian Reactor 1 BR2 Belgian Reactor 2 CBZ Central Buffer Zone CGCCR Centre Gouvernemental de Coordination et de Crise - Coördiniatie- en Crisiscentrum van de Regering EHS Environment Health and Safety Institute FANC Federal Agency for Nuclear Control IDPBW Internal Service for Protection and Prevention at Work KAL Calibration building LHMA Laboratory for High and Medium level Activity LOOP Loss Of Offsite Power NMS Nuclear Materials Science Institute NRG Nuclear Research and consultancy Group PIE Postulated Initiating Event RLE Review Level Earthquake RLF Review Level Flood SBO SCH Station Blackout Laboratories for radiochemistry with a dedicated section for plutonium handling SCK CEN Studiecentrum voor Kernenergie - Centre d'etude de l'energie Nucléaire - Belgian Nuclear Research Centre SSC Structures, Systems and Components SQUG Seismic Qualification Utility Group TSO Technical Support Organisation UHS Ultimate Heat Sink VENUS Zero power critical facility VNS Vinçotte Nuclear Safety SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 2

5 1 Objective The purpose of this document is to describe the methodology that will be followed by SCK CEN to perform the Stress Test required by European and Belgian authorities. The stress test as described below is based on the requirements and guidance given in the following documents: Belgian Stress tests specifications Applicable to all nuclear plants, excluding power reactors, 22 June Attachment to Belgian Stress test specifications List of triggering events for all nuclear plants, excluding power reactors, 22 June 2011 Presentation given by the Federal Agency for Nuclear Control during the Stress test Stakeholder meetings of 6 July and 12 August The document presented here also provides an outline of the current and planned activities in the project. 2 Stress test for the nuclear facilities of SCK CEN 2.1 Introduction The nuclear installations at SCK CEN are operated according to the national regulations and legislation in force. These regulations involve regular internal inspections and safety reviews, license granting, monitoring and review by the Federal Agency for Nuclear Control (FANC), and operational inspections by its Technical Support Organisation (TSO) Bel V to evaluate the safety level of the installations and the organisation. The framework of the periodic safety reviews for all installations of the SCK CEN assures that the most recent requirements with regard to safety are taken into account 2. Nevertheless it is important to take into account the feedback and lessons learned from the major recent events that occurred at Fukushima Dai-ichi and to verify the safe operation and the emergency preparedness of our installations in the light of these events. SCK CEN is therefore performing, at request of FANC, a re-evaluation of the safety margins for presupposed situations where its installations might be exposed to extreme events in agreement with the definition of the Stress Test by the authorities SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 3

6 2.2 Safety objective The overall safety objective of this evaluation is the prevention or mitigation of release of radioactive material, in severe accident conditions, to the environment and the public. The safety approach used in the design of the installation to achieve this is defence-in-depth, which consists in a hierarchical deployment of different levels of equipment and procedures in order to maintain the effectiveness of physical barriers placed between radioactive materials and workers, the public or the environment, in normal operation, anticipated operational occurrences and, for some barriers, in accidents at the plant Defence-in-depth Defence in depth consists of 5 levels of defence, applicable to all SCK CEN installations under consideration in the stress test: 1. Prevention of abnormal operation and of system failures; 2. Control (by detection and intervention) of anticipated operational occurrences to bring the facility back to normal operating conditions; 3. Control of design basis accidents (DBAs) to prevent evolution towards severe accidents by means of engineered safety systems. 4. Control of severe conditions including prevention of accident progression and mitigation of the consequences of a severe accident. 5. Mitigation of the radiological consequences of significant external radiological releases. Depending on the complexity and the potential impact of the installation several degrees of redundancy, separation etc. are foreseen within the SSC's carrying the above defence in depth levels to avoid a degradation of the level of defence. Further analysis of the events that occurred in Fukushima Dai-ichi are still in progress; however the immediate lessons learned showed that attention must be given to accident management and emergency response procedures. The analysis of the severe accident conditions as a function of time will be a part of the analysis to detect possible cliff-edge effects in an accident evolution. SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 4

7 2.3 Stress test at SCK CEN SCK CEN will investigate all nuclear facilities currently in operation at its site in Mol that in severe accident conditions could give rise to radiological consequences to the environment and the public. In this reassessment we will: evaluate the response of the nuclear facilities when facing a postulated set of extreme situations; verify the preventive and mitigative measures taken, following a defence-in-depth logic; examine the impact of the initiating events, the robustness of the safety functions, the sequential loss of safety functions and their effects, and the effectiveness of the severe accident management. For each of the nuclear facilities under consideration we will report on the response of the plant and on the effectiveness of the preventive and mitigative measures, noting any potential weak point and cliff-edge effect, for each of the considered extreme situations. The robustness of the defence-in-depth approach, the adequacy of current accident management measures and the potential for safety improvements, both technical and organisational (such as procedures, human resources, emergency response organisation or use of external resources) will be identified. 2.4 Reference studies and timeframe of the stress test In compliance with the requirements of the authorities the evaluation will be based on: Existing studies describing the safety of the nuclear facilities in Mol; o Safety Assessment Report of the different installations; o Synthesis reports of the different installations; o Results of the periodic safety evaluations; o Emergency response standard accident scenario s for the nuclear facilities of SCK CEN. Reassessment of the seismic study of BR2. Engineering judgement for incident and accident scenarios, involving extreme events, not available in the current design. SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 5

8 Safety walk downs with external and in house experts to examine the installations in the light of the extreme events postulated in the Stress Test. Existing emergency response procedures both internal and external. The envisaged timeframe as introduced in the "Belgian Stress tests" specifications are summarized in Table 1-1 Progress Report Final report Licensees report December 15, 2011 June 30, 2012 Regulators report February 15, 2012 October 30, 2012 Table 1-1: Timeframe of the SCK CEN Stress Test The draft content of the final report, based on the proposed methodology, is described in section 6. This table of contents can change based on the outcome of the targeted reassessment in progress. 2.5 Hypothesis In compliance with the requirements of the Stress Test we will examine the impact of the initiating events as well as the sequential loss of safety functions in a deterministic approach, irrespective of their probabilities. It has to be kept in mind that loss of safety functions and severe accident situations can occur only when several design provisions have failed. In addition, measures to manage these situations will be supposed to be progressively defeated. Alternative methods to restore or replace defeated safety functions will be examined. The analysis will be performed for all operational states of the installations, taking the most unfavourable operational state as a reference. It is also assumed that all (or several) facilities are affected at the same time, depending on the initiating event or the subsequent consequences, if this can reasonably be expected. This includes the potential degraded condition of the area surrounding the site and the neighbouring companies. The evaluation is carried out with reference to the installations as built and operated on September 30, General Methodology The methodology to reassess the nuclear installations of SCK CEN in Mol in the context of the Stress Test is based on the requirements of FANC and consists of the following steps: SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 6

9 1. Establish a list of the nuclear installations to be reassessed in the framework of the stress test based on their potential impact on the public and the environment. 2. Identify the basic safety functions of the installations to be reassessed and identify structures, systems and components that carry these functions. 3. Identify and establish the importance of initiating events conceivable at the SCK CEN site in Mol. 4. Evaluate the impact of the postulated initiating events on the safety functions; identify potential weak points or potential cliff edge effects. 5. Identify the means to maintain the three fundamental safety functions (i.e. heat removal, criticality control and containment/confinement), taking into account probable damage caused by the initiating event. 6. Evaluate the consequences of the sequential loss of safety functions 7. Evaluate the severe accident management and the emergency response; identify potential weak points or cliff edge effects. 8. Define an action plan based on the identification of potential weak points to improve the robustness of the safety function (prevention). 9. Define an action plan based on the identification of potential weak points to improve the accident management and emergency response (mitigation). 2.7 Progress and actual status of the stress test report Since the publication of the stress test requirements for all nuclear plants, excluding power reactors, lots of actions have been initiated and are still on going in the framework of the stress test. In the list below major meetings, milestones and actions are summarized; the end date is the issuing of this methodology report to the Federal Agency of Nuclear Control June 22, 2011 Stress Test specification issued by FANC July 4, 2011 SCK CEN Stress Test steering group defined July 6, 2011 Stress Test information meeting for non power facilities FANC/Bel V July 8, 2011 Initiating of the work group earthquake reassessment reactor BR2 with SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 7

10 VNS (Vinçotte Nuclear Safety) August 12, 2011 Stress Test Stakeholder meeting for non power nuclear facilities FANC/Bel V September 2, 2011 Working group on accident management and emergency response kickoff meeting September 5, 2011 Working group on air plane crash and explosions and blast waves kickoff meeting September, 2011 Presentation of the project and the requirement to managers of the different nuclear installations on site September 8, 2011 Working group meeting on flooding kick-off September 9, 2011 Meeting with other Belgian non power installations on methodology and possible mutual impact scenarios September 13, 2011 Internal presentation of the stress test activities to the Nuclear Material Science institute Coordination Committee September 16, 2011 Stress test coordination meeting to formally establish working groups, deadlines and prioritization of actions September 19, 2011 Information Exchange Meeting with the Nuclear Research and consultancy Group (NRG) on the differences and similarities between the Stress Test in the Netherlands and Belgium September 20, 2011 First SCK CEN Stress Test Steering Group meeting September 21, 2011 Accident management and emergency response working group meeting on the availability and operation of the internal fire brigade after certain initiating events September 26, 2011 Accident management and emergency response working group meeting on the availability and operation of the emergency planning room after certain initiating events September 28, 2011 Meeting with Warringtonfire Gent on the potential impact of kerosene fires on the facilities of the SCK CEN October 5, 2011 Meeting with VNS on the seismic evaluation of SCK CEN facilities other than BR2 October 12, 2011 Walk down in BR2 and LHMA by VNS seismic experts October 13, 2011 SCK CEN Stress Test kick-off meeting with representatives from FANC and Bel V October 17, 2011 Meeting with other non power installations on the selection of conceivable initiating events at the plants site October 18, 2011 Visit an walk down of the Royal Military School in the framework of the SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 8

11 air plane crash and explosions working group November 8, 2011 Meeting with Royal Observatory of Belgium and NIRAS for the selection of the review level earthquake conceivable at the nuclear zone Mol - Dessel November 9, 2011 Meeting with Tractebel Engineering on possible additional analyses regarding seismic (re)assessment of the BR1 and VENUS reactor. November 14, 2011 Second steering committee and approval of the draft methodology document by the steering committee November 15, 2011 The draft version of the methodology sent to FANC and Bel V as agreed in the meeting of October 13. November 16, 2011 Preliminary note of the accident response and emergency planning working group November 22, 2011 Draft document on the seismic reassessment of BR2 presented to SCK CEN by VNS November 29, 2011 Meeting with other Belgian non power installations on the cyber attack and the vulnerability analysis December 2, 2011 Reception of the comments from FANC and Bel V on the draft methodology as presented on November 15 by SCK CEN December 12, 2011 Walk down in LHMA and SCH by VNS seismic experts December 15, 2011 Methodology and progress report sent to FANC and Bel V 3 SCK CEN facilities examined in the stress test SCK CEN is a nuclear research centre equipped with two research reactors BR1 and BR2, a zero-power critical facility VENUS and several laboratories designed and equipped for dedicated experiments and analyses. SCK CEN has its technical site located at Mol, in the northeast of the province of Antwerp. The installations, facilities, services and laboratories at this site comprise: The BR1 reactor currently operated at 700 kw thermal The BR2 reactor with nominal power MW thermal The BR3 reactor, currently in a decommissioning stage The zero-power critical facility VENUS The hot cell laboratories (LHMA) for research on nuclear fuel and irradiated materials Laboratories for radiochemistry (SCH) with a dedicated part for plutonium handling Laboratories for research on radiobiology and radioecology SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/1834 9

12 Laboratories for dosimetry and low level radioactivity measurements including laboratories for spectrometry Central Buffer Zone (CBZ), the building for intermediate storage of radioactive waste A laboratory for the calibration of nuclear instrumentation (KAL) An underground laboratory for research into the final disposal of high level radioactive waste (HADES) The medical service The emergency planning infrastructure Workshops The installations that will be reassessed in the context of the stress test are the installations that could possibly give rise to an impact on the public and the environment in accident conditions described and evaluated in the Emergency response standard accident scenario s for the nuclear facilities of SCK CEN. The possible impact on the public or the environment is very dependent on the specific installation concerned and its activities. Although the potential consequences of extreme accident conditions in the Calibration Building and the Central Buffer Zone for waste storage are considered to be small, they will also be included in the analysis for completeness and consistency with the facilities studied in the context of the periodic safety review for external events. The following installations will be examined in the stress test: The BR1 reactor including fuel storage The BR2 reactor including fuel storage The critical facility VENUS including fuel storages The hot cell laboratories for research on nuclear fuel and irradiated materials (LHMA) Laboratories for radiochemistry with a dedicated part for plutonium handling (SCH) The calibration building (KAL) The central buffer zone (CBZ) 3.1 Identification of the safety functions for the different installations The basic safety functions identified for the different installation are given here: BR1 and BR2 research reactors Reactivity control o The capability to shut down the reactor and maintaining it in a shutdown state SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

13 Heat removal o Providing adequate heat removal after shutdown Containment/Confinement o Confining radioactive material in order to prevent or mitigate its unplanned release to the environment. VENUS The basic safety functions for the critical facility VENUS are reactivity control and confinement no active heat removal is required for its operation. LHMA, SCH, KAL and CBZ Confinement is the basic safety function for the hot cell laboratories (LHMA), the laboratories for radiochemistry (SCH), the calibration building (KAL) and the central buffer zone (CBZ). In the installations where variable amounts of fissile material can be present, structural and organisational means are implemented in order to maintain subcriticality in al operational states (handling, storage and transport). Besides the safety functions described above due consideration will be given to radiation protection in the stress test evaluation and accident scenarios of the different installations. The feedback of the Fukushima accident showed that the exposure of the response workers performing mitigating actions is an important issue. The structures, systems and components (SSC) that ensure the operation of these safety functions differ from one facility to another. The safety related key equipment will be identified for each facility and this description of the SSC performing the safety functions will be the basis for the analysis in the Stress Test. 4 Project organisation 4.1 Organisation A project has been defined within SCK CEN in order to manage, coordinate and organise the different activities necessary to perform the Stress Test. The project organisation consists of a steering committee, a project coordination group and technical subject, theme or installation specific working groups. The Stress Test -steering committee SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

14 Is composed of the director general, the deputy director general, the directors of the institutes responsible for the installations under consideration (EHS, ANS and NMS), the head of the health physics and safety expert group (IDPBW) and the stress test coordinator. Defines work groups on certain technical subjects described in the technical scope, section 5. Defines the activities in SCK CEN on the Stress Test. It performs a frequent follow up of the activities and assures that the required resources, competencies and technical skills internal or external to SCK CEN are made available in the project. Evaluates the results of the Stress Test and defines actions and priorities for improvement where necessary and possible. The Stress Test project coordination Consists of a dedicated Stress Test co-ordinator and the head of the health physics and safety expert group (IDPBW). Plans, implements and guides the activities defined in the Stress Test steering committee. Reports to the steering committee on the progress in the project. Prepares the exchange meetings with FANC and Bel V on the subject. Is responsible for the final editing of the Stress Test report. The Stress Test working groups Perform the defined Stress Test activities targeted on a specific theme and/or installation or provide support for the impact or consequence evaluation. Are groups with a varying composition depending on the technical scope or installation under study. Are defined and established based on the decisions of the Stress Test steering committee. Include the persons managing the installations, the site inspectors, analysts with the required skills and competencies and a safety advisor independent of the installations as required. A schematic representation of the organisation of the Stress Test project within SCK CEN can be found in Figure 3-1. SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

15 Figure 4-1: Schematic representation of the organization of the Stress Test project within SCK CEN 5 Technical scope and detailed methodology 5.1 Initiating events In the Stress Test we will consider a list of initiating events and also investigate realistic combinations of different initiating events and failures. The effects and consequences of these initiating events on the nuclear installation and especially on the structures, systems and components responsible for the assurance of the safety functions will be examined. SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

16 A more detailed description of the methodologies per initiating event defined in the stress test is given below Earthquake None of the facilities at SCK CEN, which were constructed in the late 1950's until beginning of the 1960s, were designed taking into account a certain earthquake level or design basis earthquake (DBE). For BR1 and BR2 a seismic evaluation was carried out in the framework of the periodic safety reviews showing that the safe shutdown can be assured after the occurrence of a seismic event. Based on modern deterministic and stochastic evaluation techniques, the seismic risk, expressed in terms of peak ground acceleration (PGA), for the Mol site can be evaluated. The earthquake level resulting from these studies is called the review level earthquake (RLE). The following points will be examined by a contracted geosciences senior expert Level of the RLE (PGA); Methodology to evaluate the RLE and validity in time; Conclusion on the adequacy of the RLE. This is the level of the earthquake evaluated for the Mol-site that will be used for the evaluation and reassessment of the robustness of the installations to earthquakes. The seismic study of BR2 performed, in the framework of the periodic safety review, at the end of the nineties will be re-examined by an external senior safety expert in the light of the assessed level of the RLE. Based on the reassessment, walk downs using SQUG (Seismic Qualification Utility Group) design analyses or complementary techniques are foreseen. The seismic evaluation of the BR1 reactor, performed in 2008 on the basis of conservative parameters, showed that the reactor can be brought to a safe shutdown after an earthquake. This study will be re-assessed in view of the evaluation of the RLE mentioned above. The seismic evaluation of the other installations and internal structures important to the safety functions will be assessed based on engineering judgement and installation walk downs. Where the event is conceivable, flooding as a consequence of a seismic event will be studied in a dedicated section. SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

17 5.1.2 Flooding Similar to the design basis earthquake, a design basis flood assessment for SCK CEN facilities has never been performed. Nevertheless an assessment of the flooding risk was performed in the framework of the periodic safety review showing a very low probability of flooding. In the framework of the Stress Test we want to re-examine the flooding risk by introducing a review level flood (RLF). The review level flood has to be derived from the flood hazard for the site, which is a probabilistic result derived from the analysis of all the possible flooding scenarios at the site. The review level flood is a series of parameters that maximize the challenge to plant safety as a consequence of flood. Possible causes of flooding in general are: flooding from rivers, flooding due to a dike breach of a canal, flooding from sewerages, tsunamis and flooding in local depressions in the landscape due to heavy rainfall. Several studies have pointed out that the probability of flooding of the technical site of SCK CEN is extremely low and the tsunami risk is non-existing. Currently, flooding at the nuclear site Mol-Dessel can only occur due to heavy rainfall accumulating in local depressions in the micro topography of the site. The review level flooding (RLF) for the site will therefore be based on the extensive knowledge of the Royal Meteorological Observatory on heavy rainfall data combined with the assumption that the soil is impenetrable. The major advantage of this simplified approach is that a representative but conservative water level can easily be derived and, combined with a micro topographic analysis of the site; weak points and vulnerable facilities can be identified and further assessed The determined water level will also provide information on the accessibility of the site for emergency workers and equipment Bush or forest fire The hazard of bush or forest fire has been examined in the periodic safety review, as the site is located near a wooded area. As a consequence different actions are already foreseen such as surveillance rounds for early detection of fires in the woods, maintenance of fire lanes, access restrictions and augmented surveillance during dry spells. The internal fire brigade co-ordinates with the local fire brigades of Mol, Balen, Lommel and Leopoldsburg. Actions have been initiated to facilitate the access of the fire brigades to the woods and to foresee supplementary access to water reserves (ground water, nearby canal). SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

18 In the stress test we will also report on emergency procedures that are initiated in the different installations in case of a forest fire. Finally, an action plan has been initiated and will continue to reduce the risk of forest and bush fires by removing certain wooded areas that might represent a real threat for some of the nuclear facilities of SCK CEN Extreme weather conditions An analysis of the frequency of occurrence of hailstorms, heavy wind, tornados, lightning, heavy snowfall and heavy frost will be performed in order to determine conceivable initiating events for these extreme weather conditions. The basic information will be provided by the Royal Meteorological Observatory in Ukkel. An analysis of the robustness of our installations will be performed based on the conceivable extreme weather conditions derived from the analysis above. Feedback on the response of the installations to past extreme weather events will also be included in the analysis Aircraft crash A detailed probabilistic analysis of aircraft crash was performed for the installation of SCK CEN for different airplane categories in the framework of the periodic safety review. The results, showing a low probability, will be commented on in the final report. In the context of the Stress Test a deterministic analysis will be performed to assess the expected damage to the building and internal structures, leading to a further evaluation of the availability of safety functions. An assessment of the building stability after a postulated aircraft crash will be performed by an external specialist in structural engineering. The effects of a consequential fire (fuel fire) after a crash will also be examined in order to assess the adequate fire fighting and accident response. Due to the nature of the information dealt with in this topic the results of this analysis will be classified (no public access) in the final report Other man-made events Computer attacks The analysis of this event will investigate the provisions to prevent system alteration and loss of control of the installations caused by a cyber-attack. This will be done in a first step by making an inventory of all computer based control systems important in the operation of the plant safety functions. The second step consists of evaluating the level of impact the computer based control systems have on the functioning of the equipment and its vulnerability to an attack. SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

19 The vulnerability management of the SCK CEN network will be evaluated on several levels (network architecture, network management policies, user policies and vulnerability auditing) including the mitigation and recovery plan after an attack. Toxic gases The impact of toxic gases on the installations of SCK CEN were examined in the context of the periodic safety review. Vulnerabilities of the control of the installation after an exposure to toxic gases were examined. The results will be re-examined and, if necessary, additional facility dependent evaluations will be made and reported in the context of the stress-test. Explosion and blast waves The impact of explosions and blast waves on the installation was also recently analysed in the periodic safety review. The analysis showed that the risk of unacceptable radiological impact as a consequence of an accident involving explosions and blast waves was very low and well below the acceptance criterion. Nevertheless in the context of this analysis we have contracted a building stability expert to further examine the expected damage of explosion and blast waves on our installations. A further analysis will then be performed to evaluate the impact on the safety functions. Due to the nature of the information dealt with in these three topics the results of their analysis will be classified (no public access) in the final report. 5.2 Loss of safety functions As discussed above we will study the impact of the initiating events on the safety functions of the installations. Special attention will be given to the following events: Loss Of Offsite Power (LOOP) and Station Black Out (SBO) Several events can lead to a loss of offsite power, with either a natural or a manmade cause. An analysis of past occurrences will be made with an evaluation of the response of the installations. The LOOP event will also be examined in combination with loss of on-site backup power (SBO). Loss of ultimate heat sink (UHS) The loss of heat sink event will be studied for the installations requiring the heat removal safety function i.e. BR1 and BR2. Combinations with a station black out will also be analysed. We will evaluate, for the events described above (LOOP/SBO and loss of UHS) and their combination, how long the site can withstand without external support. Non-conventional means SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

20 that can be used to prevent possible further degradation of the safety functions to prevent degradation of fuel/fissile material or release of radioactive materials will be identified. 5.3 Accident management and emergency response The accident management and emergency response involves an installation dependent part and a general site part. Both parts are treated in separated sections, based on the following rationale: The installation specific mitigation measures to keep the installation under control and/or the measures to correctly assess the technical status of each facility. These measures will be discussed at the level of each facility. The more general management and emergency response actions that are common to the entire site of SCK CEN and/or have an influence on our interactions with the outside world (e.g. emergency teams, neighbouring nuclear companies). These aspects will be dealt with in a separate chapter. A clear difference can also be made in the accident management for the research reactors and the other installations under consideration. For the BR1 and BR2 research reactors we will investigate: Means to protect from and to manage loss of cooling function Means to protect from and to manage loss of cooling function in the fissile material handling, storage facilities or waste facilities Means to protect from and to manage the risk of o explosions or fire; o criticality; Means to protect from and to manage loss of confinement. In the accident management of the critical facility VENUS, the hot cell laboratories, the laboratories for radiochemistry, the calibration building and the central buffer zone we will assess Means to protect from and to manage the risk of o explosions or fire o criticality Means to protect from and to manage loss of containment integrity SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

21 In the analysis due attention will be given to the resources for managing the accident situation, their availability and the possibility to deploy them during accident conditions. The impact of extensive destruction or hazardous work environments on the accident management and mitigating actions will be evaluated. A timely response to accident situations is important to avoid further aggravation of the situation. Therefore an analysis will be performed to evaluate the time before the next significant failure or possible cliff-edge effects. Topics addressed in the chapter of the general emergency response and accident management are: an assessment of the operational issues of our emergency response plan; an assessment of our interactions with the outside world; an assessment of our access to technical support means. These aspects will be studied for all initiating events in the study. A non-exhaustive list is given below. Impact of all initiating events (such as LOOP, bush fires or flooding) on the vital steps in our emergency procedures: alerting staff and start-up of the emergency plan; alerting outside actors such as the National Crisis Centre (CGCCR), the province, etc. as foreseen in the Nuclear and radiological emergency plan for the Belgian territory (KB 17/10/2003); assessing the technical status within our facilities; assessing the radiological impact on the environment. Impact of the initiating events on the supporting actions: protection of workforce and emergency workers coming to the site; operational level of our fire brigade, our laboratories, our technical support functions, communication channels and waste storages. This includes the operational status of all aspects of our emergency room. Identification of extra means available to overcome weaknesses identified above, and if needed, proposals for improvement. This chapter will also describe the auxiliary support that can (or depending on the event can't) be called in from outside the site. As this external support depends also on other actors, either private or public, this will also tackle the aspect of priority setting of e.g. public actors such as the fire brigade. 6 Content of the stress test report The final report that will be presented on June 30, 2012 to FANC will contain the following information: The document starts with the objective of the report followed by the description of the site and nuclear facilities with their potential impact on the public and the environment in accident SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

22 conditions. References to Emergency response standard accident scenario s for the nuclear facilities of SCK CEN and the safety assessment reports will be made. In the next section the list of initiating events conceivable at the plant site will be given together with information on the methodology with which they were derived. The following section will evaluate the impact of the initiating events on the different nuclear installations under consideration. An evaluation of the severity (evaluation of the margins) of the initiating event that could lead to a severe damage of the installation will be performed for earthquake and flooding. We will also examine the accident management needed when safety functions are defeated. Based on the conclusions of the evaluation an action plan of possible improvement of the safety provisions will be made. 7 Table of contents of the final report The table of contents described below is the framework and guide for the analysis. It is clear that the table of contents can change based on specific results from the reassessment. SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

23 1. Objective and methodology 2. Description of the installations 2.1. BR BR VENUS critical facility 2.4. Hot cell laboratories for research on nuclear fuel and irradiated materials (LHMA) 2.5. Laboratories for radiochemistry (SCH) 2.6. Central Buffer Zone (CBZ) 2.7. Calibration building 3. Initiating events conceivable at the site 3.1. Earthquake 3.2. Flooding 3.3. Other extreme natural events Weather conditions Bush or forest fire 3.4. Airplane crash 3.5. Other manmade events Toxic gases Explosions and blast waves Computer attacks 4. Evaluation of the impact of the initiating events and loss of safety functions on the nuclear installations 4.1. BR1 SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

24 Earthquake Flooding Other extreme natural events Air plane crash Other manmade events Influence of neighbouring facilities Loss of safety functions and combinations of events Accident and severe accident management 4.2. BR Earthquake Flooding Other extreme natural events Air plane crash Other manmade events Influence of neighbouring facilities Loss of safety functions and combinations of events Accident and severe accident management 4.3. VENUS critical facility Earthquake Flooding Other extreme natural events Air plane crash Other manmade events Influence of neighbouring facilities SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

25 Loss of safety functions and combinations of events Accident and severe accident management 4.4. LHMA Earthquake Flooding Other extreme natural events Air plane crash Other manmade events Influence of neighbouring facilities Loss of safety functions and combinations of events Accident and severe accident management 4.5. SCH Earthquake Flooding Other extreme natural events Air plane crash Other manmade events Influence of neighbouring facilities Loss of safety functions and combinations of events Accident and severe accident management 4.6. Central Buffer Zone Earthquake Flooding Other extreme natural events SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

26 Air plane crash Other manmade events Influence of neighbouring facilities Loss of safety functions and combinations of events Accident and severe accident management 4.7. Calibration building Earthquake Flooding Other extreme natural events Air plane crash Other manmade events Influence of neighbouring facilities Loss of safety functions and combinations of events Accident and severe accident management 5. Emergency response and accident management 5.1. Emergency response plan: start-up, alert, emergency response room 5.2. Emergency response plan: technical and radiological assessment 5.3. Emergency response plan: on-site mitigation of accidents 5.4. Emergency response plan: protection of workforce and emergency teams 5.5. Emergency response plan: external support 5.6. Emergency response plan: communication to the outside world 6. Overview of the actions for improvement 6.1. BR BR2 SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/

27 6.3. VENUS critical facility 6.4. Hot cell laboratories for research on nuclear fuel and irradiated materials (LHMA) 6.5. Laboratories for radiochemistry (SCH) 6.6. Central Buffer Zone (CBZ) 6.7. Calibration building 6.8. Site emergency response and accident management SCK CEN Stress Test Methodology IDPBW/FVE/BMA/2011/