Mensa warhead facility costs now over £2bn

The total budget for the troubled Mensa warhead facility at AWE Burghfield is now expected to be £2.2bn. When initially approved the project budget was £734m, but the project has become infamous for its budget increases. In 2018 the National Audit Office (NAO) revealed that Mensa was 146% over budget and six years overdue. Two years later the NAO produced a detailed report on infrastructure projects at nuclear sites, and the Mensa budget had increased from £1.6bn to £1.8bn.

Mensa was intended to replace the ‘Gravel Gerties’, which have been used for warhead assembly and disassembly at Burghfield since the 1950s. In 2018 the Office for Nuclear Regulation (ONR) ruled that use of the Gravel Gerties would only be allowed until 2026, and only if immediate changes were made to reduce risks.

In 2021 the ONR gave permission for inactive commissioning of Mensa to begin. For a number of years the MOD has been anticipating that the facility would be in service by the end of 2023. However, in the 2022 Major Projects data a completion date of May 2024 was regarded as “achievable”. This information was redacted in the 2022 data release and was subsequently disclosed to NIS following a Freedom of Information request. The Mensa project end date has been redacted again in the 2023 data release. However, it is stated that “[t]he project has been challenged to maintain pace whilst managing a complex schedule and a testing supply chain environment….[but] continues to make progress and is nearing finishing construction.”

The project is currently rated Amber in the Infrastructure and Projects Authority (IPA) annual report published in July. An Amber rating means, “significant issues already exist, requiring management attention”.

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