Submarine Dismantling Project

The Submarine Dismantling Project (SDP) will deliver the Government’s commitment to provide a safe, environmentally responsible and cost-effective solution for dismantling 27 of the UK’s de-fuelled, nuclear powered submarines after they have left service with the Royal Navy.

What is submarine dismantling?

The Ministry of Defence’s (MOD) Submarine Dismantling Project (SDP) is managed by the Submarine Delivery Agency (SDA) and is responsible for dismantling 27 nuclear submarines; 20 of which are decommissioned and have left service, while 7 currently continue to be operated by the Royal Navy.

The submarines that have already left Royal Navy service are stored safely and securely: 7 at Rosyth dockyard in Fife, Scotland and 13 at Devonport dockyard, Plymouth. They are subject to regular maintenance and checks by both the MOD, the Defence Nuclear Safety Regulator and the Office for Nuclear Regulation, to comply with the required safety, environmental and security standards.

How are we undertaking the dismantling?

UK submarines are powered by nuclear reactors. During submarine operations, nuclear reactions cause radioactive substances to be generated in the pipework and components within the reactor compartment. This requires managing after the submarine leaves service. While our submarines are being stored, waiting to be defueled and then dismantled, they pose no additional safety risk to workers or members of the public.

They undergo an annual survey and maintenance programme and a more in-depth survey and maintenance regime in nuclear-licensed docks, to preserve and test the systems as well as ensure submarine hull integrity.

Once the nuclear fuel is removed and transported to Sellafield for storage the submarine can formally enter the SDP.

The SDA is taking a three-stage approach to dismantling. This approach meets government policies for managing radioactive waste and was supported by the results of 2 public consultations in 2012 and 2015. The three-stage dismantling method allows the less hazardous parts of a submarine’s nuclear reactor core, known as Low-Level Radioactive Waste (LLW) to be removed first, followed by removal of the Reactor Pressure Vessel which is classed as Intermediate Level Radioactive Waste (ILW).

The SDP is conscious of the importance of a circular economy and therefore looks to re-use components that can be re-purposed in our operational fleet. Our experience has identified that once all the radioactive waste has been removed, around 90% of the materials on the submarines, mainly steel and other metals, can either be re-purposed or undergo conventional recycling at a licensed ship-breaking site, which forms the third and final stage of the dismantling process.

Our three-stage approach to submarine dismantling is unique and has not been attempted by any other country.

We are currently demonstrating and refining our dismantling approach and have removed LLW on the retired submarines SWIFTSURE and RESOLUTION with all the dismantling work completed safely, on time, within budget and minimising any environmental impact. LLW removal work continues now on a third submarine, REVENGE.

Latest updates

The process of dismantling a submarine is highly complex. The UK’s chosen approach to dismantling submarines is one that safely and securely manages and disposes of as much of the radioactive waste as practicably possible. This leaves fewer legacy issues for future generations to manage.

A third submarine, REVENGE, entered the dry dock in Rosyth in late March 2020 to commence its LLW removal. The intent is to remove all LLW including large components such as steam generators and pressurisers. No nation has yet attempted this complex and challenging undertaking and we are currently putting in place the techniques necessary to remove all LLW for the first time to comply with safety and sustainability standards.

LLW-removal work on REVENGE was temporarily paused due to the need to implement safety measures for personnel in accordance with the government’s COVID-19 guidelines but recommenced in May 2020.

The Submarine Dismantling Project (SDP) was approved in 2013 with the objective of delivering a dismantling and disposal solution for 27 decommissioned nuclear submarines (up to and including the Vanguard Class). The Astute and Dreadnought Class submarines are not included in the 27 boats in scope of the SDP but will be considered for decommissioning in the future.

Scrutiny reports

On 3 April 2019 the National Audit Office (NAO) published a report on Submarine Defueling and Dismantling.

The Public Accounts Committee (PAC) took evidence from the MOD on 1 May 2019 and published its report on 19 June 2019: Submarine defueling and dismantling.

The NAO and PAC reports both recognised the progress made, however, significant challenges remain. All the agreed recommendations from the PAC’s report were implemented by 31 March 2020.

MOD selects nuclear storage site as Submarine Dismantling Project progresses.
Submarine Dismantling Project: site for the interim storage of Intermediate Level radioactive Waste.
The Submarine Dismantling Project Advisory Group.
Submarine Dismantling Project: interim storage of Intermediate Level radioactive Waste.
Submarine Dismantling Project.
Submarine dismantling public consultation - Level 4 supporting documents.
Submarine dismantling public consultation - level 3 supporting documents.
Submarine Dismantling Public consultation - level 2 supporting documentation.
Submarine dismantling consultation: interim feedback report.
Submarine dismantling public consultation: level 5 supporting documents.
Submarine Dismantling Project - our approach to decision making.
Glossary of terms used in the Submarine Dismantling Project.
Submarine dismantling project: technical options study.

Published 20 May 2021
Last updated 24 June 2021 + show all updates
  1. Added a 'Related documents' section and updated latest updates.

  2. First published.