The UK’s Defence Infrastructure Organisation (DIO), part of the Ministry of Defence (MoD), has awarded a £3m contract to restore access and egress point capability for vessels at 3 Basin in HMNB Devonport, to its “original leak free intent”, according to a UK Government notice.
The work will allow “the safe and secure storage of Laid Up Submarines, future surface ships, and other strategic assets for a minimum [of] 80 years”, read the DIO contract notice, published on 19 May. The deal was awarded to Preston-based engineering company Volkerstevin on 23 January this year and has an expected end date of 31 August 2024.
Laid up in 3 Basin at HMNB Devonport is the legacy of the UK’s nuclear submarine capability, with 13 decommissioned Royal Navy nuclear-powered attack submarines (SSN) inside its perimeter. Water level controls are typically used to manage the volume of water inside such sites, depending on leak rates.
Water egressing some naval locations used to store nuclear-powered vessels is routinely tested for contaminants, with the leak at Basin 3 located along the southern wall section.
Speaking to Naval Technology, an MoD spokesperson said: “Work is planned at 3 Basin at HMNB Devonport, to address minor seawater leakage from the basin and weathered stone edgings. The leak does not present an environmental risk and both the basin and entrance gate remain structurally sound.”
Submarine Dismantling Project
The repair work being undertaken to 3 Basin at HMNB Devonport is understood to not be a part of the ongoing Submarine Dismantling Project (SDP), a multi-year programme intended to scrap dozens of nuclear-powered submarines once in service with the Royal Navy (RN).
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The majority of submarines stored at Rosyth, Scotland, and Devonport, England, are thought to have been defuelled since being decommissioned, although hazardous and classified materials remain onboard, requiring specific clearances and capabilities to be disposed of safely.
The SDP’s mandate is intended to fully dismantle 27 of the UK’s nuclear-powered submarines after they have been defuelled, including the ballistic missile boats (SSBN) that housed the country’s nuclear deterrent.
In February 2022, the MoD revealed that HMS Valiant would be the first nuclear-powered submarine in Devonport to undergo dismantling. According to a 2019 investigation by the UK’s National Audit Office into submarine defuelling and dismantling, the MoD spent an estimated £500mn since 1980 on storing and maintaining its retired nuclear submarines.
HMS Valiant was commissioned into service in 1966 and served for less than 30 years before being decommissioned in 1994. It is not known what impact, if any, repair works to 3 Basin will have on its planned disposal.
The boats at Devonport and Rosyth are kept in an afloat condition, having had their nuclear fuel removed for disposal. However, the complicated nature of scrapping and recycling a nuclear submarine has meant that the boats have been left hidden in plain sight, as the MoD determined the best method to dispose of the vessels.
The UK currently has four of the latest Astute-class SSNs in service or commissioned (Astute, Ambush, Artful, and Audacious), with a fifth, HMS Anson, undergoing sea trials. The UK also operates a single remaining Trafalgar-class SSN, HMS Triumph.
In addition, the RN operates four Vanguard-class SSBNs (Vanguard, Victorious, Vigilant, Vengeance), which will be replaced by the incoming Dreadnought-class submarines, with the first-in-class currently in manufacture at the BAE Systems yard in Barrow-in-Furness, UK.