Project to dismantle ex-Royal Navy nuclear submarines inches forward

There are currently 21 former Royal Navy nuclear submarines awaiting disposal, 7 in Rosyth and 14 in Devonport. Here we look at the process and the modest progress in efforts to dismantle them.

Kicking the can down the road

Since the 1960s, nuclear submarines have become arguably amongst the most important defence assets of the UK. An outstanding industrial, and political effort during the Cold War provided the RN with a formidable nuclear submarine force. Unfortunately, successive governments failed to make arrangements for the timely disposal of these boats. In a less environmentally conscious era, filling the boats with concrete and sinking them in the deep ocean was the original plan but the disposal of nuclear waste at sea was banned by the London Dumping Convention in 1983. Planning for the dismantling of these submarines should have been started at that time, but only in the last 10 years has there been a serious effort to grip the issue.

Small reactors sealed up and contained within the boats do not represent a great hazard but maintaining them safely while they await dismantling is a growing drain on the defence budget. More than £500M has been spent on submarine storage and maintenance since the RN’s first nuclear boat was withdrawn.

Over time the nuclear regulatory frameworks have become ever-more demanding than when the submarines were conceived. Stricter rules have added more complexity and cost to the dismantling process, ironically adding delays and increasing the amount of nuclear waste awaiting appropriate disposal. HMS Dreadnought decommissioned in 1980, has now been tied up in Rosyth far longer than she was in active service. In the civil nuclear industry, operators are required by law to put aside funds and make plans during the life of the plant to pay for decommissioning. It would be prudent if a similar principle was applied by the MoD to all new nuclear submarine construction.

Besides the attraction of deferring costs in the short-term, a major cause of delays has been the selection of a land storage site for radioactive waste. Low-Level Waste (LLW) is stored at Sellafield in concrete-lined vaults and in 2017 URENCO Nuclear Stewardship Ltd at Capenhurst in Cheshire was selected as the interim site for storing the more dangerous Intermediate Level Waste (ILW). The Reactor Pressure Vessels (RPV) removed from the submarines are classed as ILW and will temporarily be stored in purpose-built buildings above ground. They will eventually be moved to a permanent underground Geological Disposal Facility (GDF) but successive governments have failed to agree on a site for the GDF that needs to be built in the 2040s.

Afloat storage

While awaiting dismantling, decommissioned submarines are stored afloat in a non-tidal basin in the dockyard.  The 7 submarines in Rosyth have all had their nuclear fuel rods removed but of the 14 in Devonport, 10 are still fuelled. This is because in 2003 the facilities for de-fuelling were deemed no longer safe enough to meet modern regulation standards and the process was halted. Submarines that have not had fuel removed have the reactor primary circuit chemically treated to guarantee it remains inert and additional radiation monitoring equipment is fitted.

Apart from regular monitoring, once every 15 years each boat has to be dry-docked for a Survey and Docking Period (SADP) which involves hull inspection and preservation work.

Reasons to accelerate disposal

Cost. The expense of afloat storage and maintenance of decommissioned boats is rising – currently costing approximately £30M per year. Every further delay adds to this and will have to be funded from a defence budget that is much smaller in real terms than when the boats were ordered and built during the Cold War. The total disposal cost will be at least £3bn over 25 years and continue into the 2040s. (This is for the 27 boats listed above – Astute-class dismantling is not yet being considered.) All this effort and expense is a drain on precious MoD resources for zero operational gain with each delay adding to the cost.

Legacy. It is unacceptable to leave waste for future generations to deal with and it is simply common sense to dispose of old equipment at around the same time their replacements come online. Responsible care of the hulks afloat means they pose minimal risk to the environment or local population, but a tiny risk does remain. This makes some people living nearby uneasy and provides another grievance for those ideologically opposed to nuclear submarines and Trident. The minimal environmental hazard they pose is sometimes exaggerated by media, politicians and campaigners to suit their own agenda. The old boats are also a rather uncomfortable reminder of the time when the RN had an SSN force approximately double the strength it is today.

Space. When HMS Trenchant is moved to 3 Basin at Devonport for storage, the basin will be at its licensed capacity. Currently, the MoD only has permission from the nuclear regulator to store 14 boats. Approval to hold 16 will be needed in order to accommodate HMS Talent and Triumph when they decommission. Storing more boats in Rosyth is not an option because of limited space in the basin which is also used for civilian vessels as well as by the aircraft carriers to access the dry dock. Once the purpose-built disposal facility at Devonport is up and running in the early 2030s, it will be more efficient (and likely deemed politically less sensitive than anything in Scotland).

Progress at Rosyth

The Submarine Dismantling Project (SDP) finally started at Rosyth in December 2016, around 15 years behind schedule. A team of around 150 people are working on the site pioneering the two-stage process to remove radioactive waste. Swiftsure was the ‘pilot’ submarine for the project and stage 1 – the removal of LLW. This work was completed and the boat was sealed up and returned to afloat storage in the basin during August 2018. So far, 129 tonnes of mainly metallic LLW have been removed from Swiftsure and Resolution. Many of the older boats have asbestos lagging around pipes, which also has to be removed with exceptional care and disposed of in sealed containers. Stage 1 work on Resolution was completed on time in March 2020 and on budget.

Stage 1 work on Revenge started in March 2020 but was suspended on the 24th due to COVID lockdown and (almost) normal working was not resumed until June 2020. Stage 1 work should normally average about 18 months per boat and by late 2021 the project had involved 600,000 man-hours with no accidents or environmental incidents.

Work on the first boat to undergo stage 2 – removal of ILW, will start in late 2025 and should be complete by 2026/7. This will be a notable achievement as the first Pressurised Water Reactor (PWR) anywhere in the world to be dismantled. Other nations use a much simpler process and cut the entire reactor compartment out of the submarine and transport it structurally complete for burial in land storage facilities. The US has successfully disposed of over 130 nuclear ships and submarines since the 1980s. The Russians have disposed of over 190 Soviet-era boats (with some international assistance) since the 1990s while France has already disposed of 3 boats from their much smaller numbers.

From submarine to razor blades

To completely dispose of an active nuclear submarine there are several steps.

The boat is formally decommissioned in a ceremony to celebrate its service. The majority of the ship’s company leaves and the vessel is handed over to Babcock. The boat is fully de-stored, internal fixtures and fittings are removed along with all classified systems and items that can be re-used by other boats. Flammable materials are removed together with rudders, hydroplanes (and in some cases the propulsors) while the hull is given treatments to help preserve its life.

During the lay-up preparation phase, a small RN duty watch is retained on board for around 2 years supporting the civilian contractors as the boat is prepared for storage in order to manage reactor decay heat, secondary and hotel systems until they can safely be fully shut down. When the boat has been stripped and no longer requires personnel on board, it is towed to the basin for storage. At the current rate of disposal, the average hulk will spend approximately 40 years afloat in the basin, undergoing SADP every 15 years.

When ready to begin the 2-stage radioactive waste removal process the boat is taken into the dry dock that has been prepared for this work. All LLW is removed, including large components such as steam generators, pressuriser and secondary circuit pipework. All radioactive material removed from the Reactor Compartment and machinery spaces is taken out through openings cut in the hull, labelled and packaged in suitable containers for dispatch to the disposal facility. This work is done in the active waste accumulation facility (AWAF) adjacent to the dock. The boat is then sealed up and returned to afloat storage.

When ready for the second stage, it is brought back to the dry dock and ILW removal begins. The primary circuit pipework and coolant pumps can then be removed. The Reactor Pressure Vessel (RPV) head is classed as LLW and is removed separately and a temporary head put in place. The primary shield tank (PST) which surrounds the RPV has to be drained of hazardous chemicals before the RPV is then attached to a lifting cradle. The RPV is then lifted out and placed in a special container ready on the dock bottom. Once the RPV is sealed in the container, it is lifted onto a transporter to be taken away. The remaining parts of the PST are also removed and cut up into manageable sizes. All liquids and materials removed during the process have to be sorted, segregated, size-reduced if necessary and packed into appropriate containers ready to be stored, reprocessed or recycled.

Only about 1% of each submarine is the more radioactive ILW. Around 4 % is LLW and 5% is non-radioactive hazardous waste. The remaining 90% is mostly steel that can be sold for recycling. (Depending on the class of boat, anything between 3,000 – 7,000 tons). The non-radioactive hulk will be made seaworthy and either towed to a conventional shipbreaker in the UK or possibly broken up in the dockyards. In 2020, the cost of preparing an SSN for tow and the tow itself was estimated at around £2M with the scrap metal worth a similar figure. Submarines are notoriously difficult to tow, even with a crew and working steering gear. There is very little ship-breaking done now in the UK (most ex-naval vessels are scrapped up in Turkey).

Disposal at Devonport

Progress at Devonport is considerably behind that of Rosyth. The unplanned refuelling of HMS Vanguard added a six-month delay as Babcock engineers were diverted from the SDP to work on the more urgent SSBN refit. The MoD also deferred the interlinked upgrades to Devonport infrastructure to support dismantling by another two years as a cost-saving measure. The Disposals and Devonport Infrastructure Team is now working on preparing number 14 Dock to become a dedicated SSN dismantling facility building on lessons learned at Rosyth.

In the early 2000s, a major upgrade to the nuclear refitting facilities at Devonport was completed (Project D154), to support both the maintenance and future dismantling of submarines. The giant 80-ton crane at the centre of the Submarine Refit Complex that used to dominate the dockyard skyline was used for lifting reactor components but this has been dismantled and replaced with a safer and more efficient Reactor Access House (RAH). The RAH is a moveable enclosure that spans the dock and is mounted on rails on the dock walls.

Number 14 and 15 dock floors were raised, multi-cellular, impact-resistant caissons now seal the dock entrances and new isolating submarine cradles have been installed along with seismically qualified dockside cranes. In addition to the docks, there is the only seismically-qualified railway in the UK and the Low-Level Refuelling Facility (LLRF) which can store spent reactor cores and fuel rods, prior to being sent for storage at Sellafield. Despite this enormous investment, further improvements are required to 14 Dock to meet the latest regulations before the dismantling project can begin. There have been significant problems with the nuclear enterprise in Plymouth, Babcock-owned Devonport Royal Dockyard Limited (DRDL) was put into ‘special measures’ by the  Office For Nuclear Regulation (ONR) in 2019 due to safety concerns and has been served several other notices for H&S failings. The dismantling work in 14 Dock is supposed to begin with ex-HMS Valiant in 2023 but it is far from certain if this start date will be met.

For de-fuelling operations, the RAH will be placed over the submarine reactor compartment and provides a stable, protected area that houses the crane and de-fuelling tools from which the operators can work safely while removing the RPV. The RAH concept has been used successfully across the basin in Number 9 dock for refuelling the Vanguard-class for some years.

15 Dock is being developed as the facility for Astute Class submarines fleet time and refits. (Currently, this is done in the ship lift at Faslane). On completion of the last major Trafalgar class refit, surveys are underway to establish the material state of the dock and key enabling services. The Submarine Waterfront Infrastructure Future (SWIF) project will see the conversion of 10 Dock and a 5 Basin berth to support Dreadnought class SSBN maintenance. Number 9 Dock is likely to be the site for the eventual dismantling of the four Vanguard-class boats.

End game

To some extent, the MoD is stuck in a vicious circle whereby the cost of storing submarines eats into the budget for their disposal. The modest progress at Rosyth in the last 5 years is encouraging but the glacial pace of work in Devonport is more concerning. There are always more pressing priorities for defence expenditure and the dismantling project has been continually delayed. In the meantime the nuclear and health and safety regulatory requirements that must be met are getting stricter, adding further costs. There is almost complete reliance on Babcock for UK submarine support activity and there is a very finite number of SQEP with nuclear expertise available to recruit in the UK.

Like so many problems in defence, the failure to dispose of the boats cannot be blamed on one person, government or company, rather a series of decisions made by many individuals that seemed justifiable at the time. There must be some sympathy for those working to deal with this legacy today, although the thrust of 2019 HoC Public Accounts Committee report on submarine disposal efforts can be summarised as saying “this is simply not good enough”.

This is a fully revised and updated version of an article originally published in 2018

(Main image: LLW being removed from HMS Revenge in Dry dock at Rosyth, January 2022. Via: Forces News)