§ Mr. Frank Allaunasked the Secretary of State for Defence for how long the two Chatham dockworkers working on HMS "Churchill" were exposed to radiation; and how the dose they received compares with that of a typical X-ray examination.
§ Mr. Pattie[pursuant to his reply, 7 May 1982, c. 151]: The technical investigation into the employment of two dockyard workers in a radioactive contaminated area of the nuclear complex at Her Majesty's dockyard Chatham has been carried out. The information requested by the hon. Member on 7 May—[Vol. 23, c. 151]—and also on 22 April—[Vol. 22, c. 136–7]—is as follows:
(1) The nature of the incident did not require that a Board of Enquiry be convened. It was considered that MOD internal procedures were sufficient for the purpose. A Technical Investigation was held to establish the circumstances which gave rise to the incident and necessary action is being taken to minimise the risk of a similar occurrence in the future. I am forwarding copies of the replies to the questions you have raised to the UCATT Shop Stewards' Convenor.
(2) The departure of the previous first level supervisor who would have been directly involved was part of the planned rundown of the Chatham Non-Industrial workforce. The new supervisor was qualified for the post and there have been no other changes to line management in this area.
248W(3) The chippings were contained within the enclosed area surrounding the Active Waste Tank and were subsequently removed in the normal way using Health Physics Control Procedures.
(4) Work on the Active Waste Tank in this instance was undertaken without protective clothing because the two men involved were not positively advised of the radioactive hazards involved (see note 8 below). They were, however, wearing lint dust masks which provide some protection against inhalation of active material.
(5) Both men are fit and well and are at work. Lung surveys carried out on the men showed some traces of activity but the levels were less than 1 per cent of the International Commission on Radiological Protection recommended maximum annual limit of intake and less than 5 per cent. of the recommended investigation level (see 12 below).
(6) It is forbidden to wear any overalls in dining areas and this rule was in force at the time of the incident. The two men would have worn contaminated overalls in the locker areas as at the time they were not under Health Physics Control. A radiological survey was carried out immediately the incident came to light. This indicated that no radioactive contamination had been transferred to the lockers or locker rooms.
(7) The overalls used by both employees were examined immediately following the discovery of the incident and found to be contaminated. The level of contamination was just equal to the statutory level at which action is required to remove the contamination. The overalls were accordingly removed for treatment.
(8) Written work instructions which would have indicated that a radiological hazard was involved were raised but due to human error they were not passed to the supervisor before he ordered the commencement of work. Procedures are being introduced to minimise the risk of any similar occurrence in the future.
(9) There is no statutory requirement for controlled area working notices to state actual levels of radioactivity. Warning notices indicating that the area was an active area had been posted and a radiological boundary properly and clearly established before the incident. By the time of the incident the effectiveness of the boundary had been degraded. Although the two men involved in the incident and their supervisor were not deterred by the degraded barrier, two other men and their supervisor from a different trade saw it and reacted appropriately. The necessary action is being taken to minimise the risk of a similar occurrence in the future.
(10) The nightshift technical supervisor, is a classified radiation worker having spent some nine years working inside the nuclear complex, including the reactor compartment. The remainder of the supervisory staff had considerable experience of this type of work.
(11) All classified or approved scheme workers employed in the Nuclear Complex at Chatham Dockyard, as in all nuclear licensed establishments, receive some exposure to radiation from time to time. Procedures exist to ensure that such exposure is kept to the absolute minimum. All such workers are volunteers and there is careful monitoring to ensure that the levels of exposure accumulated do not exceed the statutory doseage levels.
(12) The two men worked on the Active Waste Tank for three nights. The potential hazard was inhalation of dust from paint chippings. This hazard was reduced because the men wore lint dust masks. Measurements taken within two days of the incident indicate that the maximum dose each man received was equivalent to half the dose received from a normal chest X-ray and only 15 per cent. of that received from a mass-miniature (ie mobile) X-ray unit. Use of Whole Body Monitoring Facilities at DRPS Alverstoke were offered verbally to the men and they initially declined. The offer was then repeated in writing and they now intend to make use of the facilities today.