Office for Nuclear Regulation

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HM Nuclear Installations Inspectorate

Relicensing the Atomic Weapons Establishment Sites to AWE plc


Health and Safety at Work Act

1. The operators of nuclear plants in the UK must, like their counterparts in other industries and places of work in general, conform to the Health and Safety at Work Act 1974 (HSW Act)8. This Act places a fundamental duty on employers to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all their employees. It also imposes a duty to ensure, so far as is reasonably practicable, that persons not in their employment are not exposed to risks to their health or safety as a result of the activities undertaken.

The Health and Safety Commission (the Commission, or HSC) and Health and Safety Executive (the Executive, or HSE)

2. The HSC and HSE were created in 1974 by the HSW Act. The Commission has a Chairman and nine part time members, appointed by the Secretary of State for the Environment after consultation with organisations representing employers, employees, local authorities, and others as he thinks appropriate. The Commission is responsible to the Secretary of State for the Environment and to other Secretaries of State for the administration of the HSW Act. In particular, the Secretary of State for Trade and Industry answers in Parliament in relation to nuclear safety.

3. The Commission's duties are, both directly and by encouraging others, to take appropriate steps to secure the health, safety and welfare of persons at work; to protect the public generally against risks to health or safety arising out of work activities and to control the keeping and use of hazardous substances. The Commission also conducts and sponsors research; promotes training, and provides an information and advisory service. It keeps under review the adequacy of legal requirements and submits to Government proposals for new or revised regulations and approved codes of practice.

4. The Commission has general oversight of the work of the Health and Safety Executive and has power to delegate to the Executive any of its functions. It is however precluded from giving directions to the Executive about the enforcement of the Act in any particular case. The HSC makes substantial use of independent advisory committees to advise it directly. The HSC's independent adviser on the subject of nuclear safety is the Nuclear Safety Advisory Committee (NuSAC).

5. HSE is a statutory body which employs over 3500 staff engaged in developing health and safety policy, inspecting the premises of duty-holders and enforcing health and safety legislation, investigating work-related accidents and complaints, and providing information, guidance and advice on health and safety matters. HSE is also the statutory licensing authority for non-Crown bodies which operate nuclear sites, a function which it delegates to senior officials within HM Nuclear Installations Inspectorate (NII) which is part of HSE's Nuclear Directorate.

Nuclear Installations Act 1965 (as amended)

6. Those parts of the Nuclear Installations Act 1965 (as amended) (NI Act)1 which relate to nuclear safety are relevant statutory provisions of the Health and Safety at Work Act. Under the NI Act, no site may be used for the purposes of installing or operating any reactor or other specified nuclear facilities unless a nuclear site licence has been granted by the Health and Safety Executive (HSE) for that site.

7. The NI Act is nationally and internationally recognised as strong and effective. Central features of it are the granting of licences by HSE to the "users" of sites (see Glossary), and the attachment of conditions to such licences. The grant of a nuclear site licence imposes liabilities and duties for safety on licensees who are required by the licence conditions to establish and implement arrangements for the key activities affecting safety.

A Permissioning Regime

8. The regulatory regime which NII operates under the terms of the Nuclear Installations Act requires that all significant actions by the licensee (essentially those having implications for nuclear safety) are subject to vetting and approval by NII. It is therefore described as a 'permissioning regime since licensees are unable, for example, substantially to modify plant or to alter operating arrangements without submitting their proposals to NII for consideration.

9. The nuclear permissioning process is unique in that the safety case which supports compliance with the licence is subject to continuing review. The resources and effort to deal with an individual duty holder are spread over the lifetime of the installation rather than falling at discrete periods determined by legislation.

Controls Used by NII

10. NII interacts with its licensees using a wide variety of legal instruments under powers delegated by the Executive when administering the provisions of the Nuclear Installations Act 1965 (as amended). These powers enable NII to:

  1. grant licences to applicants;
  2. vary a licence, to reduce the area of the licensed site;
  3. attach conditions to the licences, and to vary or revoke those conditions;
  4. Consent to particular actions, usually to the commencement of a given activity;
  5. Approve particular arrangements or documents, generally to "freeze" them so they cannot be changed without NII agreement, e.g. emergency arrangements;
  6. Notify the licensee that it requires certain information to be submitted e.g. a safety case;
  7. issue Specifications to call in particular documents for examination, or Specify that something must be done in a particular way, e.g. form of waste material;
  8. issue licence instruments as a means of agreeing to particular plant or process modifications;
  9. Direct the licensee to shut down particular operations.

11. The first three of these are comparatively infrequent events. Most of the remainder, i.e. (iv) to (viii), are likely to be much more frequent, and generally reflect the rate of change on the site covered. These actions result from a request from or application made by a licensee (or prospective licensee). In general they will have been signalled to HSE in advance of receiving the formal request, and will often be the subject of considerable discussion, during which the views of each side will be well aired, before the NII exercises its powers.

12. NII may from time to time reject or refuse a licensee's formal application. On occasion the NII may deem it necessary to call on its reserve power to issue a direction to close down particular operations for safety reasons. The various actions which can be taken under the licence are described more fully in Appendix 1 to this Annex.

Other regulators

13. The requirements for the protection of the environment and the authorisation of discharges of radioactive waste from nuclear licensed sites are the responsibility of the Environment Agency for England and Wales and the Scottish Environment Protection Agency for Scotland. Enforcement of certain legislation concerning the transport of radioactive matter, other than on nuclear licensed or relevant (i.e. Crown) sites, rests with the Radioactive Materials Transport Division of the Department of Environment, Transport and the Regions.

The Nuclear Site Licence

14. The safety of nuclear installations in the UK is the responsibility of holders of nuclear site licences and is assured through a system of regulatory control. A nuclear site licence, which can only be granted to a corporate body, permits the use of a site for specified activities. Licensing applies throughout the lifetime of an installation from design, siting, construction, commissioning, operation, and modification to eventual completion of decommissioning.

15. Under the NI Act, no site may be used for the purposes of installing or operating any commercial nuclear power plant unless a nuclear site licence has been granted by the HSE. The Nuclear Installations Regulations 1971 added a number of other types of prescribed installations for which a nuclear site licence is also required. A licence is not transferable, but a replacement licence may be granted to another corporate body. Before this can be done, NII will apply the same evaluation criteria as it would for an initial licensee. Its evaluation of an application considers three main aspects - the organisation; the location; and the activities. A licence may be revoked by HSE or surrendered by the licensee. However, in either event, the licensee will retain absolute legal responsibility for the nuclear safety of activities on the site until there has ceased to be any danger from ionising radiations from anything on the site.

Licence Conditions

16. HSE is able to attach to a licence, at any time, such conditions as appear to it to be necessary or desirable in the interests of safety, including conditions relating to the handling, treatment and disposal of nuclear matter. HSE also has power to vary or revoke conditions so providing scope for the licence to be tailored to specific circumstances and the phase of the installation's life. In this way the licence becomes a regulatory tool by which HSE can define the areas in which the licensee should pay particular attention to nuclear safety matters.

17. HSE has developed a standard set of conditions which provide consistent safety requirements and are non-prescriptive and flexible. Each licensee can develop arrangements which best suit its business whilst demonstrating that safety is being properly managed.

18. While the licence conditions provide the basis for control by NII, they do not relieve the licensee of the responsibility for safety. They are phrased in general terms making the licensee responsible for the application of detailed safety standards and safe procedures for the plant. The arrangements which a licensee develops to meet the requirements of the licence conditions constitute elements of a safety management system. NII reviews the licensee's arrangements to see they are clear and unambiguous and address the main safety issues adequately.

19. Licensees' licence condition arrangements are a focus for NII's inspection activities backed up by assessment of written submissions from licensees, particularly safety cases. Assessment is made by NII's specialists against NII's guidance documents such as HSE's Safety Assessment Principles14 (SAPs), which gives standards against which to judge the adequacy of safety of plants.

20. A set of 35 standard conditions was used in all licences granted from 1990 and, following various relicensing exercises, these standard conditions had been attached to all nuclear site licences by 1997. However in 1999 it was decided, based on experience in the UK and abroad, that it would be desirable to clarify the arrangements for regulating organisational change, not least to assist licensees in understanding their duties and responsibilities. Accordingly a thirty-sixth licence condition was introduced explicitly relating to changes to organisational structures and resources.

21. The new licence condition requires each licensee to make and implement adequate arrangements to control any change to its organisational structure or resources which could affect the safety of its licensed sites. The new condition will ensure that before a licensee makes an organisational change he must consider the safety implications. For changes that could have a significant effect on safety if they were inadequately conceived or executed the new powers enable NII to require the licensee to submit a safety case, and to prevent the change from taking place until satisfied that the safety implications are understood and that there will be no lowering of safety standards. The text of the new condition is reproduced in Appendix 2 to this Annex.

Safety Management Prospectus

22. An applicant for a nuclear site licence is expected to provide NII with a Safety Management Prospectus (SMP) which demonstrates that the applicant has a proper commitment to health and safety, an adequate management structure, arrangements, etc. to discharge its obligations associated with being a nuclear licensee. A SMP can be regarded as that part of the licensee's safety case which deals with management issues (the items that should be covered are indicated in HSE's publication "Nuclear Site Licences - Notes for Applicants"6). By this means NII expects to receive a clear statement about a company, its structure, organisational arrangements and how it proposes to operate.

23. The type of organisation and magnitude of resource needs to be commensurate with the risk. The licence applicant's SMP leads to a demonstration of a commitment to health and safety through:

Safety cases

24. A safety case is a suite of documents providing a comprehensive written demonstration that risks have been reduced to a level which is as low as reasonably practicable (ALARP - see Glossary). The safety case is not a one-off series of documents prepared to obtain a nuclear site licence. It is intended to be a living entity which underpins every safety related decision made by the licensee. The safety case is required to be updated regularly and the implications of proposed plant and other safety related changes have to be examined and, when necessary, additional demonstration of safety provided. Accordingly, the requirements to produce and maintain safety cases are embodied in conditions attached to all nuclear site licences.

25. NII examines the safety case to satisfy itself that the claims of the licensee are justified or demonstrated. For site inspections, NII uses the safety case to help to prepare for inspections and to determine parameters and values against which to judge the adequacy of safety of the plant.

Operational Methods

26. The sections of the NI Act relating to the licensing and inspection of sites are relevant statutory provisions of the HSW Act which also provides the arrangements for enforcement. NII Inspectors are appointed under the HSW Act. They administer the NI Act and deal with nuclear and radiological safety issues at licensed nuclear sites. NII also makes judgements on the acceptability of responses made by licensees to the requirements of licence conditions including assessment of safety cases.

It is NII's duty, in relation to nuclear and radiological safety, to see that appropriate standards are developed, achieved and maintained by the licensee and to ensure that the necessary safety precautions are taken. This duty is carried out by:


27. Assessment is the process by which NII establishes whether the licensees' demonstration of safety is adequate. The purpose of assessment by NII is to confirm the evidence that the installation is as safe as is reasonably practicable. The technical standards of safety which NII uses to judge a licensee's safety case are expressed in HSE's Safety Assessment Principles (SAPs)9. Risk can never be avoided altogether; and normally, safety means the control of risks to an appropriately low level.


28. Inspection is the means by which HSE checks for compliance with licence conditions, including safety cases, and other legal requirements, and provides a basis for enforcement and other regulatory decisions. Inspectors also seek to advise and encourage the operators of plants to continually enhance safety. Nuclear licensed sites are subjected to a high degree of inspection, one or more site inspectors being allocated to a site. A site inspector typically spends around 30% of his or her available time at site. Much of the remaining time is spent reviewing licensee's justifications of safety with other site inspectors and assessment colleagues.

29. Additionally, the NII mounts team inspections on particular topics which may be regular events, such as witnessing the annual demonstration emergency exercise for a site, or special inspections on a selected aspect of safety. Team inspection typically involves a mixture of Site Inspectors and Assessment Inspectors. The work reported here involved both types of inspection activities and included assessment of submissions. Because of the number of plants on the AWE sites, a team of four site inspectors is allocated specifically to them.


30. All inspection and assessment is done on a sampling basis, the size and scope of the sample being determined by, for example, the potential hazard of the activity and the findings from initial examinations. This reflects the normal regulatory practice of targeting and proportionality, whilst retaining the basic principle that safety is the responsibility of the licensee. It depends for its success on a suitably qualified and experienced Inspectorate.


31. In exercising the delegated licensing function, NII makes use of a number of controls derived from the licence conditions, as described above. These generally act as enforcement tools in the non-prescriptive nuclear regulatory regime. However NII inspectors may also use their enforcement powers under the HSW Act to issue Prohibition and Improvement Notices and to prosecute for breaches of that Act or the relevant statutory provisions. Breaches of licence conditions are offences under the HSW Act. HSE's enforcement powers are summarised in Appendix 1.