§ Mr. John EvansTo ask the Secretary of State for Defence (1) if nuclear submarines personnel have access to a record of their dose rates on leaving service with the nuclear submarine fleet or the armed services;
(2) what levels of radiation are (a) received by nuclear submarine personnel and (b) reported by the Central Electricity Generating Board amongst classified persons working in nuclear power stations.
§ Mr. Archie Hamilton[holding answer 16 March 1989]: The ionising radiation doses accrued by Royal Navy nuclear submarine personnel during the operation of the submarines are in general very small, being for the most part lower than those received by members of the public, who are exposed to natural cosmic and terrestrial radiation from which submariners are shielded. The majority of nuclear submarine personnel are thus not categorised as radiation workers.
Personnel who require regular access to designated radiation areas are categorised as radiation workers and subject to dosimetric assessment. Since 1986 such personnel have been isssued, on leaving the Royal Navy, with a termination record of the total dose which they have received. Before 1986, dose records were available to the individual on request. The average whole body dose received by Royal Navy submarine personnel categorised as radiation workers during 1988 was 1.5 milliseiverts.
I understand that the average radiation dose received by classified persons working in the Central Electricity Generating Board's nuclear power stations in 1987 was 0.7 milliseiverts (the 1988 figure is not yet available).
The radiation exposure limit for classified persons, set by the Ionising Radiations Regulations 1985, is 50 milliseiverts per annum.
§ Mr. John EvansTo ask the Secretary of State for Defence if he will publish in theOfficial Report the upper quartile range of maximum radiation dose rates sustained by nuclear submarine personnel in the last five years.
§ Mr. Archie Hamilton[holding answer 16 March 1989]: Figures for the radiation doses sustained by nuclear submarine personnel are not easily broken down into quartiles. The following table gives the cumulative total dose, the average individual dose and a breakdown of numbers of personnel by dose received for each of the last five years.
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Number of personnel in dose ranges Year Cumulative dose (man Seiverts) 0–15 mSv 15–20 mSv 20–30 mSv 30–40 mSv 40–50 mSv Over 50 mSv Average individual dose (mSv) 1988 2.1 1,398 4 0 0 0 0 1.50 1987 2.6 1,307 19 12 4 0 0 1.90 1986 3.1 945 19 18 16 1 0 3.07 1985 2.9 905 18 16 10 3 0 3.05 1984 2.8 777 24 13 6 0 0 3.46 Note: mSv =milliseivert.
§ Mr. John EvansTo ask the Secretary of State for Defence what level of radioactivity his Department judges as significant in regard to the discharge of radioactive materials from nuclear submarines into the sea; and what type of materials are involved.
§ Mr. Archie HamiltonRoyal Navy submarines do not discharge radioactivity at sea under normal circumstances. The significance of such discharges depends upon their potential effect. In determining what levels are acceptable, therefore, the Royal Navy takes into account the recommendations of the International Commission on radiological protection regarding dose. The radioactive isotope of most significance in discharges from Royal Navy submarines would be cobalt 60.
§ Mr. John EvansTo ask the Secretary of State for Defence how his Department knows either in which foreign ports Britain's nuclear submarines may berth, or into whose territorial waters those submarines may enter.
§ Mr. Archie HamiltonWhenever a Royal Navy nuclear-powered submarine wishes to visit a foreign port, a request is made to the authorities of the country concerned.
§ Mr. John EvansTo ask the Secretary of State for Defence what assessment his Department has made of the consequences of an accident involving the nuclear armed warheads of the Polaris class of submarine boats in berth, and when at sea nearby the coastline, with regard to the guidelines recently published by the Health and Safety Executive entitled "Tolerability of Risk".
§ Mr. Archie HamiltonThe consequences of a Polaris nuclear weapon accident have been thoroughly examined. The hazard from such an accident would be from contamination by nuclear material which might be dispersed by a fire or ignition of conventional explosives. The risks of such an accident occurring are extremely small, and are assessed as consistent with the HSE guidelines on the tolerability of risk, although these were drawn up with nuclear power stations rather than weapons in mind. Plans do, however, exist to deal with such an accident.
§ Mr. John EvansTo ask the Secretary of State for Defence if his Department regards nuclear submarine personnel as equivalent to classified persons, as specified by the Ionising Radiations Regulations; and what measures are implemented to monitor and safeguard the health of such submariners, and to maintain the radiation dose exposure records of such personnel.
§ Mr. Archie HamiltonMost nuclear-powered submarine personnel are not categorised as radiation workers. Of those who are, a proportion are designated as classified persons using criteria laid down in the Ionising Radiations480W Regulations 1985. Radiation protection advisers are appointed, and dedicated staff qualified in radiation protection are provided in each nuclear-powered submarine and in their operating bases. Where required, dosimetric assessments are made by the defence radiological protection service.
§ Mr. John EvansTo ask the Secretary of State for Defence if dose rate records for submariners working aboard nuclear submarines are maintained on a national register; and if those records are transferred to, or available to, future employer; of such personnel.
§ Mr. Archie HamiltonA national register of radiation workers is currently being produced within the United Kingdom. The doses accrued by nuclear submarine personnel will be included within the register unless the individual concerned chooses not to have his name entered. The requirements for termination records laid down in the Ionising Radiations Regulations are complied with, and for any radiation worker a summary of the dose received can be provided.
§ Mr. John EvansTo ask the Secretary of State for Defence if his Department has knowledge of any medical disorders associated with radiation dose uptake amongst past and present submarine service personnel or their offspring.
§ Mr. Archie HamiltonThe Ministry of Defence has no knowledge of any medical disorders arising from the exposure of RN nuclear submarine personnel to radiation.
§ Mr. John EvansTo ask the Secretary of State for Defence what is the average whole body radiation dose equivalent receipt or uptake of submariners aboard a nuclear submarine during an average tour of duty.
§ Mr. Archie HamiltonThe average radiation dose per annum for those submarine personnel designated as radiation workers is included within the breakdown of dose statistics which I gave earlier today. The average tour of duty with an individual submarine is about two years. The majority of submarine personnel, on the basis of their type of employment and access to radiation areas, are not designated as radiation workers and are not, therefore, subject to dosimetric assessment.
§ Mr. John EvansTo ask the Secretary of State for Defence (1) if his Department has identified and evaluated the worst credible nuclear accident in the operation of its nuclear powered submarine fleet, its predicted frequency, and the severity of its consequences both in terms of an individual positioned at each operational dockyard station perimeter and, separately, for nearby populations beyond that perimeter;
(2) what assessment his Department has made of the consequences of an accident involving the nuclear powered 481W reactor of a nuclear submarine in berth, at either a refit dockyard, at Z-berth, or any other port of call, with regard to the guidelines recently published by the Health and Safety Executive entitled "Tolerability of Risk."
§ Mr. Archie HamiltonAccident probabilities and consequences for nuclear-powered submarine reactor accidents have long been identified and evaluated. These predictions have subsequently been compared with the Health and Safety Executive guidelines on the tolerability of risk, and are consistent with these. The predictions are used in the formulation of accident response plans for the berths in question, in consultation with local civil authorities.