REPPIR / HIRE Fault Assessment

Transcription

1 Page 1 of 22 REPPIR / HIRE Fault Assessment SITE BUILDING NUMBER PLANT SELLAFIELD VARIOUS SELLAFIELD SITE DOCUMENTATION DOCUMENT No. SL/2013/REPPIR/DOC 10 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx REVISION NUMBER Rev 1 TITLE REPPIR Report of Assessment (RoA) to Meet the Requirements of the Radiation (Emergency Preparedness & Public Information) Regulations [REPPIR] DATE October 2013

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3 Page 3 of 22 Executive Summary Sellafield Ltd is the Site Licence Company (SLC) charged with management and operation of the Sellafield nuclear complex located at Seascale Cumbria. Sellafield Ltd is owned and managed by, Nuclear Management Partners Ltd (NMP) under contract to the NDA (Nuclear Decommissioning Authority). Sellafield Site has a long history of safe operation. The safety standards used in the design, construction, operation and maintenance of its nuclear installations reduces the risk of accidents which could have a consequence for the general public to a very low level. Nevertheless the provisions of the Nuclear Installations Act, under the terms of which, Sellafield Ltd is granted its Site Licence, require that the company put in place arrangements to deal with emergencies. The aim of the many organisations involved in emergency preparedness, such as the local authorities and emergency services and the site operator, is to mitigate the hazards resulting from industrial accidents or other events that may affect members of the public. The Radiation Emergency Preparedness and Public Information Regulations [REPPIR] (Ref. 1) have been developed alongside principally the Control of Major Accident Hazard [COMAH] (Ref. 2) regulations to enable the responding organisations to have similar arrangements to meet the requirements of emergency preparedness for different industries. This also provides benefits for operators active in more than one of these major hazard sectors. Assessment of the adequacy of the emergency arrangements under REPPIR is the province of the Office for Nuclear Regulation (ONR) which is an Agency of the Health and Safety Executive (HSE). In this respect this Report of Assessment covers a number of aspects relating to emergency arrangements in Nuclear Site Licence Condition 11 (Clause 4). In the event an emergency provision is required under current legislation the following five aspects should be included in the emergency response: 1. The control of the accident at the site; 2. The assessment of the actual and potential accident consequences and alerting the relevant authorities and the public; 3. Introduction of countermeasures to mitigate the consequences as regards [i] individuals who could be affected in the short term and [ii] longer term effects such as the contamination of food supplies, land and adjoining waters; 4. Information to the public affected or likely to be affected by the event [was Public Information for Radiation Emergency Regulations (PIRER) but now in REPPIR]; 5. The return to normal conditions. The Emergency Plans in place for the Sellafield site are currently approved as adequate to deal with the items above. The Emergency Plans are based on Fault Analysis studies and are drawn up against a Reference Accident for the site. Currently the emergency actions are based on (a) The Reference Accident and (b) the principle of extendibility. a) A reasonably foreseeable accident with significant consequences extending to a defined zone

4 Page 4 of 22 closely surrounding the installation, the Detailed Emergency Planning Zone (DEPZ 1 ), extending from the centre of the Sellafield site, within which arrangements to protect the public by introducing countermeasures are planned in detail. b) Emergency Plans need to be capable of responding to accidents which, although extremely unlikely, could have consequences beyond the boundaries of the DEPZ. The measures that are required to extend the detailed arrangements cannot be precisely planned because the nature and potential of accidents can vary, for example according to weather conditions, and the exact response would be based on an assessment made at the time. The response may make use of local and national plans prepared to deal with a wide range of emergencies. This Report of Assessment (RoA) has been prepared in accordance with the requirements of REPPIR Regulation 6(4). The report documents the findings of the Hazard Identification and Risk Evaluation (HIRE) review process that has been undertaken [REPPIR Regulation 5(2)] to identify reasonably foreseeable radiation emergencies that may potentially arise at the Sellafield site. The assessment has also identified a bounding Reference Accident and the requirement for an off-site emergency plan pursuant to a reasonably foreseeable radiation emergency [REPPIR Regulation 9(1)]. The bounding 5 msv dose contour from the Reference Accident identified in the HIRE extends to a distance of up to 6 km from the centre of the current Detailed Emergency Planning Zone (DEPZ) around the site. 1 The DEPZ is informed (not prescribed) by technical assessment of area off-site in which a member of the public may receive 5mSv dose). The DEPZ: - Recognises uncertainties with completeness, frequency and consequences associated with severe accident analysis. - need not be circular.

5 Page 5 of 22 CONTENTS 1 Introduction Schedule 5 items for inclusion in RoA Schedule 5a Schedule 5b Schedule 5c Schedule 5d Schedule 5e Schedule 5f Schedule 5g Schedule 5h Schedule 5i Schedule 5j Schedule 5k Schedule 5l Schedule 5m Schedule 5n Schedule 5o Schedule 5p Conclusions References Figures List of Figures Figure 1 Outline Plan of Sellafield and Windscale Nuclear Licensed Sites...21 Figure 2 Location of Sellafield Site...22

6 Page 6 of 22 1 Introduction 1. This document is the report of assessment to the Health and Safety Executive (HSE) and the Local Authority for the Sellafield Ltd (SL) licensed site, as required under the Radiation (Emergency Preparedness and Public Information) Regulations 2001 [REPPIR] (Ref. 1). 2. This document incorporates the 3-yearly review of the Hazard Identification and Risk Evaluation (Ref. 3) which has been undertaken in accordance with Regulation 5(2). 3. REPPIR requires the following aspects to be included in the emergency response: The control of the accident at the site; The assessment of the actual and potential accident consequences and alerting the relevant authorities and the public; The introduction of countermeasures to mitigate the consequences as regards to individuals who could be affected by the short term and longer term effects. 4. The requirements of REPPIR regulation 9(1) are met by a single off-site emergency plan developed and co-ordinated by Cumbria County Council, which will liaise, as appropriate, with other local authorities. This single plan encompasses activities undertaken by SL and is prepared with the co-operation of these and many other agencies that contribute to the off-site response. 5. The requirements of REPPIR regulation 7(1) (the Operator s Emergency Plan) are met by SL s Emergency Arrangements which also meet the requirements of the Nuclear Site Licence. These Emergency Arrangements address those activities undertaken by SL on the Sellafield site. 6. REPPIR establishes a framework of emergency preparedness measures to ensure that members of the public are: Properly informed and prepared, in advance, about what to do in the unlikely event of a radiation emergency occurring, and: Provided with information if a radiation emergency actually occurs. 7. To inform the continuing validity of the current SL emergency plans, a thorough review of the site Hazard Identification and Risk Evaluation (HIRE) has been conducted (Ref. 3). 8. The HIRE review has used for its sources of information all of the safety cases that govern the conduct of operations across the whole of the Sellafield site. It is worthwhile noting that the safety cases and their underlying safety assessments are living documents which have been subject to full due process in terms of checking, review and approval, and give a much wider range of plant analysis than any that could have been carried out within a reasonable time specifically for the REPPIR review. It is noted that SL safety cases have to use demonstrably pessimistic data. Notes on Scope 9. Transport Packages approved for transportation outside the Sellafield site are not in the scope of the REPPIR assessment. Transport Packages have to meet national and international safety requirements to a high level of robustness. In respect of this submission Sellafield Ltd is an operator rather than a carrier 10. The off-site chemotoxic effects of an accident on the Sellafield site are addressed via the site COMAH report.

7 Page 7 of 22 2 Schedule 5 items for inclusion in RoA 11. The following sections are titled to relate specifically to the REPPIR schedule 5 items required to be included in the report. 2.1 Schedule 5a Particular to be included The name and address of the operator or carrier 12. The postal address of the Operator is: Sellafield Limited, Booths Park, Chelford Road, Knutsford, Cheshire, WA16 8QZ 13. The Company Registration Number is Schedule 5b Particular to be included - The Postal address of the premises where the radioactive substance will be processed, manufactured, used or stored, or where the facilities for processing, manufacture, use or storage exist 14. The postal address of the site is: Sellafield Ltd., Seascale Cumbria, CA20 1PG 2.3 Schedule 5c Particular to be included The date on which it is anticipated that the work with ionising radiation will commence or, if it has already commenced, a statement to that effect 15. The Sellafield site has been supporting nuclear operations since 1951 and work with ionising radiation has been conducted on the site since that date. 2.4 Schedule 5d Particular to be included A general description of the premises or place including the geographical location, meteorological, geological, hydrographic conditions and, where material, the history of the premises

8 Page 8 of 22 Location 16. Sellafield is a Nuclear Licensed site located on the west Cumbrian coast adjacent to the Irish Sea on the western outskirts of the Lake District National Park. Its location is Ordnance Survey grid reference NY Figure 1 and Figure 2 show the site and the area around the site. The Windscale site is fully contained within the boundary of the Sellafield site. Sellafield Ltd holds licences for operation of both the Sellafield and Windscale nuclear licensed sites 17. Apart from the existing nuclear facility, no other current industrial land use is present in the immediate area and the surrounding area is largely agricultural. 18. The local authority is Cumbria County Council. History 19. The Nuclear Licensed site is some 300 hectares in area and is built on the site of a disused munitions factory. The Sellafield site has been supporting nuclear operations since Sellafield was the location of the original atomic piles and associated processing facilities for material to enable atomic weapons production and was the location of Calderhall, the first commercial nuclear power station built in the UK (now ceased operation but not yet defuelled). 21. The site's principal activities are nuclear fuel reprocessing, decommissioning and the operation of a number of waste storage facilities. Meteorological 22. The site is adjacent to the Irish Sea on the southwest-facing stretch of the Cumbrian coastline. The foot of the Cumbrian Mountains lies some 2 or 3 km to the northeast, these mountains rising to a maximum height of 977 m on Scafell Pike, the highest point in England, 19 km to the east. The site therefore receives no shelter from the prevailing humid, often cloudy and rainbearing, winds from the southwest but does receive strong shelter from north-northeasterly through easterly to southeasterly directions. As these are also the coldest wind directions in winter, this factor combined with the relative winter warmth of the adjacent sea, results in the relatively low incidence of frost and, particularly, snow. 23. Site wind speed records are available for over fifty years at Sellafield and show a maximum gust (as recorded at the Sellafield Meteorological Tower) of 46.1 m/s (103 mph) in It should be noted that there is no history of major structural damage to plant due to strong winds at Sellafield, although there have been a number of incidents involving lesser damage to building cladding and construction sites. 24. Sellafield has its own meteorological station just outside the site fence at National Grid reference: NY which records wind speed and direction, daily maximum and minimum temperature, rainfall amount and sunshine duration. 25. The average annual rainfall is approximately 940 mm (Ref. 5) - a high figure for a lowland area due to exposure to Atlantic and Irish Sea weather systems. There is a marked annual cycle in rainfall; autumn months typically yielding about twice as much rainfall as spring months (about 100 mm/month versus about 55 mm/month). The average annual number of rain-days (rainfall more than or equal to 0.2 mm) is 186 days with 26 of these days exceeding 10 mm. The rate of rainfall increases rapidly inland towards the mountains and exceeds 3000 mm/year near Scafell.

9 Page 9 of 22 Geological 26. West Cumbria is not an area of high historical seismicity. No seismic events with a magnitude to damage conventional well built constructions have been recorded in the vicinity of the site in recent history. Aviation activities 27. All aircraft (commercial, military and general) are restricted from flying at a height of less than 2200 ft within a circle of radius 3.7 km around the Sellafield site. 28. The Sellafield site is located far from major commercial flight paths. The nearest airports are at Carlisle (70 km north) and Barrow (40 km south), neither of which presently represents significant commercial aviation activity locations. Hydrographic 29. The Sellafield site is adjacent to the Irish Sea and is within the catchments of the rivers Calder and Ehen. Discharges and oversight 30. Marine discharges are via a pipeline which discharges into the Irish Sea. 31. Discharges to the air and via pipeline are subject to authorisations issued by the Environment Agency. 32. The site is subject to regular inspection and approval by the HSE s Office of Nuclear Regulation (ONR). 2.5 Schedule 5e Particular to be included A description of any radioactive substance on the premises which is likely to exceed any quantity or mass specified in Schedule 2 or Schedule 3, as the case may be, which description shall where practicable, include details of the radionuclides present and their likely maximum quantities. 33. The quantities of radioactive material present on the Sellafield site exceed the quantities of the relevant materials identified in REPPIR Schedules 2 and The main parts of the sites radioactive material inventory (as of 2010) are as follows: High Level Waste (HLW) - 1,620m 3 Intermediate Level Waste (ILW) - 66,500m 3 (exc Windscale), - 67,170m 3 (inc Windscale) Separated plutonium Te 35. Details of the quantities of radioactive materials present in specific locations on the site are excluded from this report for security reasons. This more detailed information has been made

10 Page 10 of 22 available to the ONR within existing safety case reviews to enable their comprehensive review of SL s assessment. 2.6 Schedule 5f Particular to be included In case of assessment by a carrier, a description of any radioactive substance which is likely to exceed any quantity or mass specified in Schedule 4 or Schedule 3, as the case may be, which description shall where practicable include details of the radionuclides present and their likely maximum quantities 36. Note that Schedule 5f relates to a carrier s assessment of transport of radioactive materials and thus is not applicable for this report. Off site transportation of material is excluded, however the transport of materials within the site boundary has been considered. 2.7 Schedule 5g Particular to be included Except in the case of an assessment relating to transport, A plan of the premises in question and a map of the environs to a scale large enough to enable the premises and any features which could affect the general risk in an emergency to be identified 37. A plan of the site is given in Figure 1. A map of environs is given in Figure 2. This report of assessment and underpinning HIRE covers both the Sellafield and Windscale licensed sites. 2.8 Schedule 5h Particular to be included A diagram and description of any single plant or enclosed system containing more that the quantity or mass of any radioactive substance specified in Schedule 2 or Schedule 3, as the case may be, or, in the case of the transport of more than the quantity or mass of any radioactive substance specified in Schedule 4 or Schedule 3, as the case may be, the nature of the containment of the radioactive substance, the type of vehicle and means of securing the load within or on the vehicle. 38. Diagrams and descriptions of the specific plant or systems containing significant quantities of radioactive material are excluded from this report for security reasons. This information is available to the ONR via the safety case process to enable their comprehensive review of SL s assessment. 2.9 Schedule 5i Particular to be included Those factors which could precipitate a major release of any radioactive substance and the measures to be taken to prevent or control such release and information showing the maximum quantity of radioactive substance which, in the event of a major failure of containment, would be released to the atmosphere including, in respect of the premises, the identification of plant and other activities anywhere on the premises which could precipitate such release

11 Page 11 of The majority of identified potential faults will not result in any release of particulate radioactivity to the open environment, by the virtue of the prevention, mitigation and protection provisions installed and maintained in each facility. For a significant release of radioactivity from a nuclear facility to be possible, it is necessary for an initiating event to propagate and overcome all the barriers between the hazardous radioactive materials inside the facility and the outside environment, or for these all to fail at the time of demand. These barriers have been designed to accommodate the material itself, taking account of the physical, chemical and radiochemical properties and form of the material. The physical boundary of the facility forms part of the containment system as well. Given that all of these barriers are breached, then some radioactivity could be transported out of the facility and be dispersed into the atmosphere. For many postulated accident scenarios this would be through a designed and authorised discharge point, so mitigation by appropriate filters would minimise the particulate release. 40. The identification of specific plant or other activities on the premises which could precipitate such a release has also been excluded from this report for security reasons. This information has been made available to the Office for Nuclear Regulation via the safety case process to enable their comprehensive review of SL's assessment. 41. The HIRE review has identified as the Reference Accident a scenario in which a major release of radioactive substance could occur. The reference accident is based upon seismic damage to a number of facilities leading to the release of radioactive material. 42. Information on the maximum quantity of radioactive substance that could be released to the atmosphere in the event of a major failure of containment is excluded from this report for security classification reasons. This information has been made available to the Office for Nuclear Regulation via detailed assessment and analysis documentation underpinning the HIRE review. This information is largely drawn from safety case studies already available to ONR Schedule 5j Particular to be included Those factors which could precipitate a smaller but continuing release of any radioactive substance and the measures to be taken to prevent or control such releases to atmosphere 43. Scenarios assessed to have the potential for a smaller and, in certain cases, continuing release of radioactive material include: Undetected loss of radioactive material from containment xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxx 44. The safety case for each facility shows that all reasonable steps are taken to reduce the likelihood of these faults and to reduce the consequences should they be initiated. Suitable engineering and operational controls are identified to ensure that risks are minimised Schedule 5k Particular to be included Those factors which could give rise to an incident involving the initiation of an unintended self-sustaining nuclear chain reaction or the loss of

12 Page 12 of 22 control of an intended self-sustaining nuclear chain reaction and, in either case, the measures to be taken to prevent or control any such incident 45. The three primary factors that could give rise to an unintended criticality event at Sellafield include: Overbatching; the unintended assembly of a critical mass of fissile material in a configuration that makes a criticality event possible; Geometry, the assembly of a critical mass of fissile material in a configuration that makes a criticality event possible; Unintended presence of a moderator into an area where significant quantities of fissile material are present in a configuration that makes a criticality event possible. 46. Basic design features of the processes and products plus operational controls give assurance of the safety of all work with nuclear material, including storage. These controls have been subjected to criticality assessments and have been confirmed to give a high level of protection against an unintended criticality event in all locations on the Sellafield site. 47. Both engineered and management controls are used to prevent any of these conditions existing. These controls are detailed in the relevant facility safety cases Schedule 5l Particular to be included Information concerning the management systems and staffing arrangements by which the radioactive substance is controlled and by which the procedures are controlled Safety Management System 48. SL has a Safety Management System with suitable and sufficient arrangements in place to meet the requirements of the Nuclear Site Licence for Sellafield. These arrangements include the fundamental requirements of radiological safety for doing all that is reasonably practicable to minimise operational doses, risks and the initiation of abnormal events, particularly those which could escalate to major accidents. 49. Conditions for the safe operation of individual facilities are derived from detailed risk and safety assessments of each facility, reported in the relevant safety case, thus complying with Nuclear Site Licence Conditions (Ref. 4). In this respect this Report of Assessment covers a number of aspects relating to emergency arrangements in Nuclear Site Licence Condition 11 (Clause 4). All safety related Structures, Systems and Components are subject to appropriate examination, inspection, maintenance and testing. Key operational requirements necessary for safe operation are highlighted in formally approved Operator Instructions. In addition, processes are in place to ensure scrutiny and control of changes, whether these are to engineered systems, site services, procedures, organisational structures or resources. 50. The Head of Site is responsible for the safe operation of Sellafield, and also overall responsible for ensuring that adequate numbers of staff are present on site to operate the plants and ancillary plant in a safe manner, and that these staff are suitably qualified and experienced. This process is supported by appropriate Safety Committees. Procedures

13 Page 13 of It is a requirement of the Nuclear Site Licence that adequate quality assurance arrangements are made and implemented for all matters which may affect safety. These arrangements are specified in the top tier of a multi-tiered system and define the requirements for procedures and instructions for the site as a whole. 52. Sellafield Site procedures have been developed to ensure a common approach to many generic activities. Detailed operating instructions have also been developed and are implemented within each operational facility. 53. Key limits and conditions necessary for safe operation of the facilities are identified as Operating Rules. The work required to maintain the plant in a safe and reliable condition is specified prompted and recorded within a formal maintenance management system. Emergency Organisation 54. Sellafield Ltd has emergency plans that ensure that suitably qualified and experienced people are available at all times to respond to any events that cause the various plants to deviate from their normal operating conditions. The provision of an on-site plan and suitably qualified and experienced staff to respond to unusual events further reduces the probability of a major release of radioactivity to the environment. 55. The two emergency plans, both on-site and off-site, for SL are formally approved by the ONR and exercised regularly. Emergency planning is discussed at several cross nuclear industry forums which bring together nuclear operators, government bodies, independent advisors and local authorities to ensure that best practice in emergency planning is communicated to all stakeholders. 56. Further details on the Sellafield emergency organisation are given in the response to Schedule 5p (Section 2.16 of this report). Staffing Arrangements 57. Each department has a team of personnel, all of whom are suitably qualified and experienced for the work which they are expected to perform. A continuous shift system is operated at Sellafield which ensures that there are adequate staff resources available at all times to operate the site safely and to deal with any emergency situation which might arise. Minimum safety manning levels have been determined and are maintained for all key operations. Staffing Arrangements - SECC 58. The duty Site and Safety Shift Manager (S&SSM) is a suitably qualified and experienced person (SQEP) to enable full emergency control while waiting for relief by the duty Site Emergency Controller (SEC) and associated specialist support teams. Shift personnel will assume sufficient manning of Site Emergency Control Centre (SECC) and associated roles to cope with the initial impact of any emergency. The SECC is responsible for the tactical management of the entire Sellafield site. The S&SSM and duty SEC have delegated authority from the Head of Site to take action(s) necessary to respond to an incident including, but not limited to, rationing of supplies, sheltering, mustering, roll call and evacuation. 59. The critical safety functions of the SECC are:

14 Page 14 of 22 to establish and maintain command and control in the event of a severe accident/event; and to establish and maintain internal and external information flow to key decision makers in the event of a severe accident/event. 60. The SECC is permanently manned by the S&SSM and is located in the same building as the SF&R control room. During the day, the other SECC roles are filled by a team of day workers and shift workers. With the exception of the S&SSM, the SECC team members are volunteers who have a main work role and other safety related roles. 61. All duty team members are trained against role profiles (defined in the Site Emergency Instructions, SEI) and are assessed as SQEP and appointed to their role. 62. Occupied buildings have trained Building Controllers present to manage the building in an emergency situation. Groups of Building Controllers report to SECC via trained Area Controllers. 63. Each of the key posts in the SMC and SECC is manned by nominated day staff who are available throughout the 24 hour period according to a duty roster (comprising eight teams) and who will be called in by telephone or pager as appropriate. 64. In silent hours the SECC on-call duty team are expected to respond within one hour for key decision makers and three hours for technical support and backup. 65. Access Control Points (ACP) are set up to control access into and out of affected areas. Incident Control Centres (ICCs) and are established to control actions within the affected plants. Both the ACP and the ICC report up to the SECC. The ACPs and the ICCs are manned by plant personnel. Staffing Arrangements SF&R 66. Sellafield has a dedicated Fire and Rescue service (SF&R) with a range of fire fighting appliances, tenders and a number of pumps. In addition to the extensive water distribution networks, there are also strategically positioned water bowsers around the site. SF&R own all breathing apparatus sets on the site and are required to be in attendance for all breathing apparatus entries. 67. SF&R can provide several functions, to assist with re-entry into buildings, deployment of pumps to provide cooling or make-up water, dealing with chemical spills, rescue of injured personnel and, of course, to attend fires. Staffing Arrangements - off site technical support for accident management 68. Arrangements exist for the operators of other nuclear sites to provide assistance in the event of a Site Incident or Sellafield Emergency. 69. Support is available from both Regional & National capability, e.g. fire tenders/pumping units. Regulatory Oversight 70. The Nuclear Industry is regulated by the Office for Nuclear Regulation (ONR), which is part of the HSE. The ONR has assigned inspectors for every licensed site besides maintaining a central

15 Page 15 of 22 pool of specialist assessors. A site inspector has the right to inspect any equipment or procedure at short notice and the right to require the Company to provide information. The ONR can direct the shutdown of any process that it considers unsafe. 71. The ONR require that the safety of plant and operations is considered in a systematic manner at all stages from design, construction, commissioning, operation and decommissioning and that the safety case is subject to both continuous review and formal periodic review. 72. Any significant changes in procedures, plant or management structure have to be approved by the ONR in accordance with Nuclear Site Licences arrangements. 73. The Environment Agency (EA) has the responsibility for regulating the site s compliance with appropriate discharge authorisation and with appropriate environmental legislation. Engineering Controls 74. All safety critical equipment is carefully designed, well built, thoroughly tested and examined, operated under carefully considered operational rules, maintained according to a maintenance schedule and operated within specification by trained staff. The safety arguments for the equipment and its operation are prepared by suitably qualified and experienced personnel and subjected to careful review both internally and external to the Company. All new equipment or changes in the operating rules are considered by a series of Safety Committees containing appropriate subject matter experts as well as Company representatives. This regulator expects all papers and designs submitted to it to have been subjected to rigorous Independent Nuclear Safety Assessment. 75. The primary design concept is to contain the radioactive material and radiation. This includes, where appropriate having material in a form which intrinsically retains radioactivity within the normal range of operational temperatures and environments. Extra containment barriers can be used to restrict the release of any radioactivity which does escape from its normal location. These barriers can be passive or dynamic, where approved codes of practice allow ventilation systems, decontamination systems or pressure vessels to be designed to allow work with radioactive materials without it contaminating the normally manned working areas or the wider environment. Massive barriers are used when radiation shields are required. The maintainability and fault tolerance of these safeguards is included in the design process. 76. There are many barriers, engineered and procedural, to ensure that the release of radioactivity to the environment is kept as low as reasonably achievable. These ensure that the equipment used the Best Available Technology and is well designed, built and maintained and is operated within its safe working range. Systematic Analysis 77. The design of the plant is based upon the fundamental requirement of radiological safety to do all that is reasonably practicable to minimise operational doses, risks and the initiation of abnormal events. The last factor requires consideration of how to prevent deviations from the planned normal operations escalating to major accidents. This is achieved by careful design with redundancy, diversity and segregation of safety functions to minimise dependencies between the protective systems which deal with deviations from the planned operating envelope. Further, mitigation is applied to minimise, so far as is reasonably practicable, the consequences of any

16 Page 16 of 22 accident. Hence there is a philosophy of having defence in depth in all nuclear plant to ensure, so far as is reasonably practicable, the safety of all people in and around the plant. 78. Part of the safety assessment process includes a systematic identification of the factors with a potential to cause a major release of radioactivity or unacceptable reduction of safety margins used to control criticality hazards. This provides a comprehensive schedule of initiating events and the associated safeguards, mitigation and emergency response plans. 79. The probabilities and consequences of each potential accident are considered and combined as appropriate to evaluate risks. This process highlights those areas of the plant or operations or maintenance requiring attention to enhance safety. Improvements can be aimed at reducing the likelihood of an initiating event or at detecting its onset and either preventing it developing or mitigating its consequences. The primary consideration is to do all that is reasonably practicable to avoid the initiating event occurring, or at least to minimise its likelihood. Nevertheless, there may still be some identified events with the potential to develop into a major release. In these cases it is necessary to provide further protection to enhance safety. 80. Having done all that is reasonably practicable to prevent the initiating event from occurring there may still be some identified events with the potential to develop into a major release. In these cases it will be necessary to provide further protection to enhance safety. The safety philosophy requires that the protection provided be commensurate with the risks involved. 81. Thus for potentially serious events there must be appropriate fault tolerance. This may require redundancy 2 and diversity 3 in the methods used to identify the initiation of the fault and to bring the system back into a safe condition. Safety systems must also consider segregation 4 so that the likelihood of them all being damaged at the same time (e.g. by a fire) is reduced and they must be robust enough to survive reasonably foreseeable spontaneous external events which may, for example, include major earthquakes and the effects of lightning strikes. Detection and mitigation 82. The detection systems are geared to providing mitigation, via warnings for staff to evacuate the affected areas or take shelter if sufficiently far removed from the imminent hazard. 83. For most faults, there are multiple and diverse means to detect that a fault condition has been initiated, with the detection mechanism then prompting operator intervention to remedy the situation. 84. Faults are detected by the continuous monitoring of the key parameters identified by the systematic analysis. 85. Multiple containment barriers are used for all forms of fissile material even if the form is not amenable to dispersal during accidents. Ventilated areas provide additional dynamic containment capability in many facilities. 2 Redundancy - In this context redundancy means there must be more than one system capable of delivering an action so that if one system fails or is under maintenance the required action is still delivered 3 Diversity - In this context diversity requires that the different systems are designed in different ways or work on different principles so that if there is a design or build fault on one system it does not affect the effectiveness of the others. The required action would still be delivered. 4 Segregation - Systems must be segregated by either distance or engineered structures in such a way as to greatly reduce the likelihood that they could all be damaged by the same external event.

17 Page 17 of Separate systems are used to detect criticality incidents in those limited areas where such warning systems are justified. These Criticality Incident Detection Systems (CIDS) are designed to warn those persons in surrounding areas to immediately evacuate to minimise their dose from external exposure. Xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 2.13 Schedule 5m Particular to be included Except in the case of an assessment relating to transport, information about the size and distribution of the population in the vicinity of premises to which the report relates 88. The countryside immediately around the Sellafield site is mainly utilised for farming or residential purposes. There are no significant industrial establishments within 5 km of the Sellafield site; the nearest significant establishment in the chemical and allied industries is a contract manufacturer and processor of custom chemicals at Workington (32 km north). The gas platforms in Morecambe Bay are, at nearest, 50 km away and gas from the field is landed at Barrow (38 km southeast). The nearest military site is a firing range at Eskmeals (15 km south). 89. The major local towns of Whitehaven, Workington and Barrow are approximately 14 km to the north, 25 km to the north and 38 km to the southeast respectively. There are about 200 people living within 2 km of the site: the nearest settlement of any size is Seascale 2.5 km distant, with a population of about Gosforth is 4 km distant with a population of approximately 1300, Egremont is 7km distant with a population of approximately 6,000. The nearest point of the Lake District National park is at some 3 km distant Schedule 5n Particular to be included An Assessment of the Area which is likely to be affected by the dispersal of any radioactive substance as a result of any radioactive emergency and the period of time over which such dispersal is likely to take place 90. The Site Reference Accident (a reasonably foreseeable radiation emergency from which a member of the public might potentially receive a radiation dose of up to 5 millisieverts) identified in the HIRE review for the SL site (Ref. 3) is a release of radioactive material due to postulated damage to a number of facilities as a result of a seismic event. 91. Dose assessments have concluded that Reference Accident could affect an area up to a distance of 6 kilometres from the centre of the Sellafield site (National Grid Reference NY029038). These dose assessments include contributions from plume inhalation. Contributions from irradiation from the passing plume or from deposited material have been included. 92. The Reference Accident could continue to release activity for a period of time until the accident progression is curtailed. The release has been assumed to take place over a 4 hour period. In the case of postulated damage to a number of facilities as a result of a seismic event the overall

18 Page 18 of 22 release might take place over a longer time period. However in this case the dose would be reduced proportionately. 93. In the event of a Radiation Emergency resulting from a 'beyond reasonably foreseeable' event, the area in which countermeasures may be imposed may be extended Schedule 5o Particular to be included An assessment of the likely exposures to ionising radiation of any person or class of persons as a result of any radiation emergency 94. The maximum reasonably foreseeable radiation dose that could potentially be received by a member of the public outside the site boundary has been assessed as less than 320 msv. 95. Ingestion dose is excluded from this estimate on the basis that the exposure route is generally slow acting, and the ingestion dose contribution from the material released is low in comparison with the inhalation component. In addition, food bans can be effective Schedule 5p Particular to be included An assessment of the necessity for an emergency plan to be prepared by the operator or carrier 96. The timely imposition of countermeasures depends upon having and implementing an effective off-site emergency plan. SL therefore concludes that in order to maintain arrangements to adequately protect the public in the event of a radiation emergency, an operator s emergency plan is necessary for the Sellafield site. SLs emergency plan has been developed and improved over many years and the current plan is approved by the HSE as required by condition eleven of the Nuclear License for the site. 97. Accident management at Sellafield is defined within the Sellafield and Windscale Sites Emergency Arrangements Emergency Plan (Issue 13, September 2009) and Handbook (Issue 41, June 2011) in accordance with nuclear site license condition 11. The Emergency Plan and other components of the emergency arrangements are designed to be compatible with the offsite Emergency Plan for Sellafield produced by the Cumbria County Council Resilience Unit. Exercises of emergency procedures 98. The site carries out a range of exercises for both training and regulatory demonstration purposes. 99. The following site emergency exercises are carried out annually - 2 x Level 1 radiological exercises (ONR demonstration exercises); 1 x security exercise (ONR demonstration exercise); 1 x chemotoxic exercise (Environment Agency observation); 1-2 x roll-call and communications exercises (full site exercises; no regulatory observation); and 8 x training exercises (minimum).

19 Page 19 of 22 3 Conclusions 100. This Report of Assessment fulfils SLs duty under regulation 6 of REPPIR This report confirms that the quantities of radioactive material present on the site exceed the quantities of relevant materials in REPPIR Schedules 2 and SL has assessed the factors that could precipitate a release of radioactive material from the site following a release or a criticality event. SL has also identified the systems and control measures in place to prevent such a release or criticality event or to mitigate the effects of such a release or criticality event in the unlikely event that either was to occur SL has assessed that a Radiation Emergency is reasonably foreseeable at the Sellafield site. The maximum radiation dose to a member of the public from a reasonably foreseeable radiation emergency at Sellafield has been calculated to be less than 320 millisieverts (msv) The bounding 5 msv dose contour from a reasonably foreseeable radiation emergency at Sellafield extends to a distance of 6 km from the centre of the current Detailed Emergency Planning Zone around the site SL has assessed that an Operator s Emergency Plan continues to be necessary for the Sellafield site.

20 Page 20 of 22 4 References Ref. Title Author Issue Date Other Refs. Ref. 1 Radiation (Emergency HSE 2001 Preparedness and Public Information) Regulations 2001 Ref. 2 Control of major accident hazards (COMAH) HSE 1999 Ref. 3 Hazard Identification and SL July xxxxxxxxxxxxxxxxxxxxxxxx Risk Evaluation for 013 xxxxxxxxxxxxxxx Sellafield Site xxxxxxxxxxxxxxxxxxxxx Ref. 4 Licence condition handbook. Ref. 5 Sellafield Ltd, Final Report to ONR on the application of the ENSREG Stress Tests to the Sellafield Site ONR 2011 SL- - April content/uploads/2012/08/sellafield- ENSREG-Stress-Test-Report- CHMSC_11_P0012-final-forpublication.pdf

21 Page 21 of 22 5 Figures Figure 1 Outline Plan of Sellafield and Windscale Nuclear Licensed Sites Windscale Site Sellafield Site

22 Page 22 of 22 Figure 2 Location of Sellafield Site