The emergency arrangements for each nuclear licensed site are contained in two documents: an Emergency Plan, approved by the Health and Safety Executive, which specifies the essential principles and an Emergen­cy Handbook which contains comprehensive details of emergency procedures, manpower and equipment. The contents of the latter document are not subject to

formal approval but may be varied at the request of the HSE.

The emergency plan contains the definitions of var­ious accident categories ranging from a site incident standby to a full emergency alert, together with the conditions under which they would be declared and the staff who are empowered to make or cancel such declarations. The definitions of the accident categories are as follows:

• Site Incident This is a hazardous condition which is confined in its effect within the site security fence.

• Site Incident Standby This is the stage when a warning is given on the station that a potential site incident exists or is believed to be imminent.

• Site Incident Alert This is the stage when a warning is given that a site incident exists.

• Emergency This is a hazardous condition, the ef­fect of which is to cause, or is likely to cause, a radiological hazard to the public in the vicinity of the station.

• Emergency Standby This is the stage when a warn­ing is given that a potential state of emergency exists or is believed to be imminent.

• Emergency Alert This is the stage when a warning is given that an emergency exists.

Typical examples of plant conditions that would re­quire the declaration of the various categories of accident at a magnox station with a concrete pressure vessel are:

Condition

A rapid rise of all burst car — tride detection gear readings with abnormal BCDG filter activity.

A fire exists in the reactor with the pressure vessel intact.

A loss of coolant gas several times greater than the normal daily make-up occurs, together with a high level of radio­activity in the coolant gas.

Measurements indicate that a discharge of radioactive material which is likely to cause a hazard to the public has occurred.

The emergency plan also contains a summary of the basic emergency control organisation, the arrange­ments for communication and liaison with outside
organisations, and the level of airborne radioactivity at which action would be taken to evacuate members of the public from the vicinity of the station.

The Station Emergency Handbook is a detailed re­ference document for all personnel having emergency duties on or near to the site. Such details include the arrangements for mustering and roll-call, the consti­tution and operational procedures of all the various emergency teams, lists of emergency equipment and the operating instructions for that equipment, com­munications procedure and the location and staffing of the emergency control centres.