The site licence requires that a set of Safety Rules must be provided to give instruction as to the control and protection of personnel, to specify procedures that must be adopted and to give the limits and specifi­cation for radiation dose. Although the site licence gives limits for radiation dose levels, in general the safety rules are tighter and therefore used without prejudice to the site licence.

The safety rules make provision for personnel to be appointed to two categories:

• Senior Authorised Persons (SAP).

• Accredited Health Physicists (AHP).

Senior Authorised Persons have the responsibility to specify the conditions under which any job that has a radioactive content is to be carried out. Such con­ditions are entered in a radiological section of a safe — tv document which controls work or access to plant and areas. The information which is specified is il­lustrated in the follow ins list:

• Radiation limits imposed.

• Dosimetry required to monitor and measure the radiation dose received.

• The protective clothing required to be worn (this may include respirators or breathing apparatus).

• Confines and boundaries that are required around the work.

• Zone classification (type of radiation and or con­tamination),

• Access route between any change room and the work.

• The type of monitoring and whether required con­tinuously, intermittently or not at all.

• Time validity for the safety document.

The Accredited Health Physicists have the responsi­bility to provide a health physics service and this is illustrated as follows, although it is not a compre­hensive list:

• Advice to Senior Authorised Persons.

• Provide a dosimetry service.

• Carry out those health physics requirements within the site licence.

• Provide services for the disposal of waste.

• Give advice to the Station Manager on health physics matters and provide him with necessary statistics.

• Provide clothing and associated laundry services.

• Provide a monitoring service on and off site for the emergency plan.

• Give health physics advice to management during an emergency.

The safety rules cover two other major areas of control. These are the specifications of specific radia­tion and contamination zones, and the limiting doses to classified persons and members of the public. Controlled zones are split into two major types: con­tamination and radiation. Radiation zones have four categories (Rl, RII, RIII and RIV), the higher the R-number the greater the radiation level. RIV zones are required to have restricted access and are locked off. RIII zones would have restricted access. Contami­nation zones also have four categories: Cl and CM are contamination zones with just surface contami­nation of floors, walls and equipment, СІ 11 and CIV zones are those with airborne radioactive substances. CIV zones are sealed and access is barred except where special clothing and breathing apparatus is worn. The higher the C-number then the greater the hazard that exists.

Radiation limits are given as absolute limits but are qualified depending upon the part of the body affected. The limiting whole-body dose for a classified person is given as 5(N-18) rems, where N is the age of the person in years. The normal limiting annual dose is 5 rems (a rem is the unit currently used to express radiation), but this is qualified by not more than 3 rems in a calendar quarter. This is a whole — body dose and figures are quoted for individual parts and organs of the body where relaxation from the foregoing is given, providing the whole-body dose is not exceeded.

Members of the public and non-classified persons are limited to a whole-body dose not exceeding 0.5 rem per year.