The Repairs
to HMS Tireless

13th. Sepember 2000

Government of Gibraltar
experts report

Official Report

The HMS Tireless incident, where a UK nuclear powered submarine was successfully repaired in Gibraltar, raised many issues and concerns. The Government of Gibraltar commissioned a report from a team of experts to advise on the safety and suitability of the repair. This is the executive summary of their initial report.


Date: 13 September 2000


HMS Tireless entered Gibraltar harbour on 19 May 2000, with a leaking weld in the reactor primary circuit, and is currently berthed there awaiting repairs.

This report presents the findings of the Nuclear Safety Advisory Panel set up in response to this by the Chief Minister, Government of Gibraltar. The Panel was tasked to give an informed assessment on the nuclear safety of the submarine under repair, compared with a submarine on a normal recreational visit.

The Panel was selected for its extensive knowledge on nuclear safety, including nuclear powered submarines. The Panel used this knowledge to request, check and test the large amount of written and verbal information provided by the MoD on the proposed repairs, and to perform its own assessment.

The repair activities planned by the MoD comprise partially draining the reactor primary circuit as a necessary precursor to remaking the weld, subjecting the weld to extensive examination and then pressure testing the primary circuit.

The submarine will then depart from Gibraltar under nuclear power in the normal way.

The Panel has carefully considered the MoD plans, independently identified the nuclear safety issues and sought resolution of these issues. The scope included the safety of the submarine reactor before, during and after these repair activities, and the safety of the primary circuit water and other radioactive waste to be brought ashore for temporary storage.

The following were identified by the Panel as the key factors:

  • The long time since the reactor was shut down means that HMS Tireless is in a safer state than a boat visiting for recreational purposes, and will remain so throughout the repair period.
  • The repair operations will not introduce any significant new safety risks.
  • The water to be removed from the primary circuit and the other waste is of low radioactivity. The MoD has adopted good safety practice in their engineered and administrative arrangements for handling and storing it, until it leaves Gibraltar shortly after the submarine's departure.
  • As planned by the MoD the weld repair is very likely to be successful. The remaining uncertainties have no safety significance but may result in programme delay.
In addition, the Panel considered the option of towing or ferrying the submarine back to the UK for repairs there. The Panel has no specialist knowledge of these seamanship issues, but concluded that the option would introduce new, higher risks to the submarine, its crew and, possibly, to coastal communities.

Before reaching these conclusions, the Panel had received a significant and sufficient amount of information from the MoD, who has been co-operative.

The Panel is satisfied with the quality of the MoD safety case and the underlying safety culture. Nevertheless, it should be noted that all the above findings are largely based on the Panel's independent knowledge of the issues involved.

The Panel has therefore concluded that the proposed repair of HMS Tireless at Gibraltar does not raise any significant new safety or technical concerns.

P H Davidson
J H Large
C Milloy
A Martin

Return to Index