Written question asked by Mike Hancock (Liberal Democrat) on Wednesday, 15 June 2005, in the House of Commons. It was due for an answer on Monday, 20 June 2005. It was answered by Adam Ingram (Labour) on Wednesday, 29 June 2005 on behalf of the Ministry of Defence.

Trafalgar Class Vessels

Question: To ask the Secretary of State for Defence pursuant to the answer of 13 June 2005, Official Report, column 18W, on Trafalgar Class Vessels, what the theoretical safety concern and safety justification involved were; and if he will make a statement.

Answer: It is an essential, mandatory and routine requirement to operate a Royal Navy nuclear submarine, that a safety justification is maintained which demonstrates it is safe to do so. This requires any issues potentially affecting the safe operation of the submarine, including theoretical ones, to be considered.The theoretical safety concern on HMS Torbay and HMS Tireless centred on the potential effect of a number of small manufacturing imperfections in their nuclear reactor plant. A previous analysis had indicated that these imperfections were acceptable but a more modern analysis, using the latest information on material properties and component stress values, showed an increased theoretical risk of failure in some of these components. While there was no new defect, as part of the Royal Navy's commitment to safety, the decision was taken that the two submarines should not be operated further until the technical aspects had been fully examined and their continued safe operation could be justified. For HMS Torbay a safety justification is now in place to allow the operation of her nuclear reactor plant. The safety justification work required for HMS Tireless will be undertaken during her programmed maintenance and upgrade period, which is under way at Devonport.

Secondary information

Type: Written question
Reference: 6035; 435 c1569W
Session: 2005-06
Related items: Trafalgar Class Vessels
Monday, 13 June 2005
Written questions
House of Commons
Subjects: Trafalgar class submarines