THE Royal Navy is investigating after workers allegedly used super glue to repair a nuclear submarine.

The repair work on the Barrow-built HMS Vanguard was being carried out by defence contractor Babcock.

According to reports, 3,000 bolts on the boat were repaired by civilian workmen who had accidentally sheared off the heads of bolts that held insulation to the cooling pipes around the reactor due to over-tightening.

Instead of taking time to bore out the snapped bolts and report the damage, the workers glued them back into place, national newspaper reports said.

It was reported that repair work was being undertaken as part of a dry dock refurbishment at HMNB Devonport in Plymouth.

The unsatisfactory repairs to HMS Vanguard’s cooling pipes were discovered after a bolt fell off while being tightened during checks of the reactor chamber. 

Following the discovery, defence secretary Ben Wallace spoke with the CEO of Babcock to 'seek assurances about future work'.

The Ministry of Defence said were 'no nuclear safety implications associated with the issue identified' and preparations for final testing of the submarine’s onboard system could 'safely continue without any impact on the programme'.

A spokesperson said: “As part of a planned inspection a defect was found from work done in the past when HMS Vanguard was in dry dock.

"It was promptly reported and fixed.”

A Babcock spokesman said: “Any quality-related issue is a huge disappointment, but our own robust inspection processes discovered the issue, and we have taken immediate action to resolve it.

“Safety remains our most important priority and we can confirm there was no safety or operational impact from the work.

“We will continue to work closely with our customer, as we have throughout this most complex and critical of programmes.”

The £3 billion submarine was built by Vickers in Barrow and was commissioned in 1993.

It is the first of the four Vanguard-class of nuclear-powered submarines whose role is to carry the Trident ballistic missile system.