The branch is responsible for reviewing the safety and gaining acceptance by the regulatory authorities of the safety of operating plant, including any modifications made to it. The branch comprises Assessment, Inspec­tion and Health Physics Sections, with the latter two aiso providing a service to the Nuclear Safety Develop­ment Branch.

Independent assessment of the nuclear safety of the CEGB’s reactors is a major part of the department’s work. It starts from the first consideration of a nuclear project, covers the design stages and continues throughout the working life of the plant. The magnox and AGR assessment section is responsible for the assessment of the CEGB’s operating gas-cooled reac­tors, A major part of this work is the assessment of the pressure circuit integrity. An example on the mag­nox reactors was the assessment of the safety case for the gas duct bellows defects, discovered at three of the earlier nuclear stations. Another example is the CO2 oxidation problem and the remedial action taken to control the effects. Having considered and agreed the safety argument for a particular problem with either the designers or the operators, or both, the Depart­ment will then take the lead in presenting the CEGB’s case to the Nil, supported as necessary by the location representatives.

Safety assessment of nuclear reactors covers a very wide area and in order to give both designers and assessors some guidance on the safety targets to be
achieved, the department has produced CEGB Design Safety Criteria which give targets to be met by the design.

Further information is given on design safety cri­teria later in this chapter.

The Health Physics Section is responsible for the independent consideration of the radiological safety of all health physics aspects of the CEGB’s opera­tions and specifically looks at radioactive waste aris — ings, accumulation and discharge of radioactive waste, transport of nuclear fuel, and radiological protection and control. It is responsible for obtaining the neces­sary authorisation for discharge from the authorising ministries and for obtaining the relevant approvals for the transport of irradiated fuel.

The inspection section has inspectors at each nu­clear licensed site who have full and free access to all parts of the site subject to normal safety limita­tions, and to all personnel on the site. They carry out independent, unbiased, and informed scrutiny of all nuclear safety related activities on the site and provide a positive link between the station and headquarters. Each site inspector has a duty to advise the station manager and his staff on any matter affecting the nuclear safety of the plant, and to report back as necessary through a formal reporting system to head­quarters. In particular, the site inspector has a duty to advise and inform the station staff of any pending implications on regulatory matters and the implemen­tation of their responsibilities under the site licence and associated regulatory requirements. The inspectors carry out their duties as far as possible in a suppor­tive and co-operative manner and invariably receive the stations’ support in fulfilling their role.