RWMAC report on MoD radioactive waste practices

ANNEX 4
DEVONPORT

1. Devonport is the largest naval base in Western Europe. It is located on the eastern side of the Hamoaze which is part of the Tamar estuary in Devon. The area of the Base includes the privatised Devonport Royal Dockyard ("the dockyard") with its major support facilities for the docking of a range of naval vessels, including nuclear powered submarines.

Devonport Naval Base

2. The naval base, most of which is both owned and operated directly by MoD, provides, inter alia, operational support for one of the UK's three submarine squadrons. As such, it carries out nuclear work similar to that undertaken at Faslane (see Annex 6).

3. While the main focus of this report, as it relates to Devonport, is on the privatised dockyard, it is important to bear in mind that operations carried out at the base also involve management of radioactive wastes. The base deals with wastes arising from the operation at sea, and maintenance ashore, of the operational submarine squadron based at Devonport. These wastes consist exclusively of solid LLW and VLLW and liquid LLW. The base's procedures for minimising and segregating solid wastes have been significantly enhanced in the period since the RWMAC visit in 1994, as has the active laundry which deals with potentially contaminated protective clothing, etc. The small amounts of solid LLW arisings are transferred from MoD to the dockyard, and consigned for disposal at Drigg under the RSA93 authorisation granted to Devonport Royal Dockyard Limited (DRDL), the private company that operates the dockyard.

4. Liquid LLW from the operational submarines is also transferred from MoD to the dockyard, being piped direct from the operational submarine berths to the dockyard Effluent Treatment Plant (ETP). The treated wastes are discharged from the plant under the RSA93 authorisation granted to DRDL (see paragraph 15).

5. There are currently three decommissioned nuclear submarines held in 3 Basin within the base. A fourth submarine is currently undergoing decommissioning. These submarines are held under full MoD control, and do not, therefore, figure in DRDL considerations. At present, the base anticipates having capacity to hold 10 decommissioned submarines by 2012.

Devonport dockyard

6. Since the early 1970s, the support provided by the dockyard has included the refuelling, refitting, deep maintenance and de-fuelling and de-equipping of fleet or "attack" submarines (those not armed with ballistic missiles). This work has been undertaken in the Submarine Refit Complex (SRC) located at the north west corner of 5 Basin and in the North Lock Complex located at the south west corner.

7. In 1987, Devonport Management Ltd (DML) was contracted by MoD to manage the dockyard, including its nuclear submarine facilities. In 1997, the dockyard was privatised as DRDL (although DML is retained as a trading name). DRDL therefore owns and operates the dockyard and its facilities, holds the nuclear site licence, and is authorisee for the radioactive waste disposal authorisations granted under RSA93.

8. In 1993, based on reductions in the planned number of operational submarines, MoD came to the view that submarine refit work could in future be concentrated at a single dockyard. Devonport became the designated site, so that, in addition to the existing fleet submarine work, the new Vanguard Class ballistic missile submarines would in due course be refitted at Devonport. The first refit is due to take place in 2002.

9. The previous Resolution Class ballistic missile vessels had been refitted at Rosyth, and the MoD decision meant that nuclear work in Rosyth, after completion of scheduled work, would cease.

10. To allow for these changes, MoD approved the modernisation and expansion of the Devonport SRC. This is aimed at bringing the existing dock structures, refuelling facilities and other services up to the latest standards, and also to provide the new infrastructure required to support the refuel and refit of the larger Vanguard submarines.

11. The naval base and the dockyard depend to a large extent on a common infrastructure, but have separate business areas defined by contract.

Dockyard upgrade work

12. There have been three main elements of the dockyard upgrade work. The first was the D151 project, noted in RWMAC's last defence wastes report3, to build a new store for holding contaminated ion-exchange resins (used to remove radioactive material from liquid wastes). This was completed in February 1998 and is designed to provide additional storage space up to 2030. The second is the 10 Dock project. This involved bringing the Dock up to nuclear standards for use as a non-refuelling dock for fleet submarines, while the main SRC docks used for such vessels, Docks 14 and 15, were upgraded. The third and main element was the D154 project. This involved both improvement of the existing facilities used for the refuelling, refitting and maintenance of fleet submarines - Docks 14 and 15, and the creation of new facilities required to meet the more sophisticated, and technologically advanced, facilities required for handling the Vanguard submarines, in Dock 9. The improvement works involve strengthening of the facilities, improvement of resistance to seismic events, installation of lower level refuelling equipment, and various safety improvement features.

Radioactive waste generation

13. Radioactive wastes in solid and liquid form arise from submarine operations, submarine maintenance, refit and decommissioning work, laundering of contaminated clothing, active laboratory work and the removal and replacement of equipment. Wastes are produced within both the base and dockyard operational areas. Those generated both from the operation of the submarines, and work carried out on them within the area of the naval base, are first transferred to DRDL before their eventual disposal under the company's RSA93 authorisations. Aerial discharges of radioactivity from the dockyard site are also made, but these are extremely small.

14. The dockyard itself deals with solid and semi-solid wastes which arise both directly and from the use of resins. The total solid waste which arises directly from submarine support work is mainly in the form of LLW or VLLW, together with very small amounts of ILW. Semi-solid resins arise from the use of techniques such as MODIX, which use ion-exchange technology to remove a significant proportion of the radioactive material from the submarine primary circuit prior to major refits and refuelling. Resins also arise from radioactive materials abatement processes carried out in the site's Effluent Treatment Plant (ETP). Resin wastes can be both ILW and LLW.

15. Liquid wastes are almost entirely contaminated water, arising from various sources, which are discharged, under the RSA93 authorisations granted to DRDL, either to the dockyard sewers or, after treatment in ETP, to the Hamoaze.

16. The most radiologically significant radionuclide in nuclear submarine waste is cobalt-60. However, significant amounts of tritium, which is less radiotoxic, are also generated within the submarine's reactor circuits, along with smaller amounts of other radionuclides.

Site regulation

17. Most of the Devonport site has been subject to civil regulation under NIA65 and RSA93 since 1987, when operations were first contracted out to DRDL (then DML). At that time, part of the dockyard, including the SRC, was designated as a licensed nuclear site. The civil regulation excludes the area of the naval base and actual submarine operations, which are subject to NNRP regulation, the procedures for which were radically revised in 1997 (see paragraph 6.11 of the main report and Annex 3). There are areas of overlap between NII regulation and that by NNRP where waste is transferred from naval base and submarine operations to the dockyard facilities.

18. Following the introduction of "Authorisation" as the system of NNRP regulation, both the dockyard and naval base were subject to NNRP audit and review. Both parts of the site achieved Authorisation in 1998.

19. DRDL currently holds five authorisations under RSA93, granted in 1997, to dispose of radioactive wastes. These cover:

- discharge of radioactive gases, mists and dusts to the atmosphere;

- discharge of radioactive liquid waste to the Hamoaze or dockyard sewer;

- disposal of solid LLW to the BNFL Drigg facility and to Sellafield;

- disposal of solid LLW by transfer to UKAEA Winfrith;

- disposal of solid VLLW to landfill.

Because of the time that has elapsed since these authorisation were granted, and also the introduction of new operations and facilities, DRDL submitted an application to vary the RSA93 authorisations to EA in May 2000. This anticipated that any new authorisation would be granted in the form of a single integrated authorisation for the site, of the kind now being used more widely by EA. At the time this report was being prepared (February 2001), EA's public consultation on the DRDL application was about to commence.

Project Omen

20. This is a project undertaken directly by MoD (using specialist contract labour) to investigate the integrity of submarine RPVs, focussed on HMS Warspite at Devonport. Bore samples are taken from one of the submarine's longitudinal RPV welds for examination and testing. This activity produces small amounts of solid ILW in the form of swarf and other waste material (such as small sections of the RPV shielded skirt) which are retained under MoD management, being packaged and securely stored within the lower level of the submarine reactor compartment. Solid LLW arisings from the project comprise one of the waste streams for which the BNFL embargo on carbon-14 contaminated wastes has been lifted.

Public relations

21. There is a Devonport Local Liaison Committee, chaired by the Naval Base Commander, at which the naval base and DRDL present a summary of site operations, data on radiation exposure, Health and Safety, and other issues. NII, EA, and NNRP attend and, where appropriate, give presentations. The Base Commander and DRDL endeavour to maintain good links with Plymouth City Council and local residents through a variety of means. There is a policy of allowing the local people and their representatives on site wherever possible. A DRDL website, providing details of the site's operations, is maintained. RWMAC understands that the naval base is about to open a "nuclear topic" building, with a range of exhibits, as a means of further informing the public.

Main RWMAC observations

General

22. RWMAC notes that the privately-owned Devonport Royal Dockyard continues to be the subject of full civilian regulation under NIA65 and RSA93, with all the external scrutiny that this entails. The Committee also notes that the submarine reactors themselves and operations at the naval base continue under MoD regulation in the form of the revised system of NNRP Authorisation.

23. With the decision to allocate the new Vanguard Class submarine work to Devonport, there is a programme of upgrade and improvement of the SRC, not least to introduce new safety features. The Committee notes that the MoD-owned nuclear support barge referred to in its 1997 report has now been decommissioned and its functions transferred to shore-based facilities. Decommissioning of a second support barge, taken out of service in late 1997, is now underway.

24. RWMAC was informed by DRDL staff of the changes to the dockyard management structure and responsibilities that had occurred since the Committee's last visit in November 1994. These changes include improvements to the process control arrangements for radioactive wastes and associated documentation which were described in the last RWMAC report. DRDL also prepares two,10 and 30 year site plans to provide a longer-term focus on its waste management planning.

25. The company's organisational and management system is designed to meet the quality system requirements of ISO9001 and also aims to satisfy those of BS5882 "A Total Quality Assurance Programme for Nuclear Installations". RWMAC was told that DRDL was seeking to develop an environmental management system to take on board the principles of ISO14001, although the company might not, in practice, seek full accreditation (for reasons not explained to the Committee).

26. Within the time and resources available to it, RWMAC has not been able to examine and evaluate the detail of all these arrangements. However, the arrangements appear, on the face of it, to represent considerable improvement since the Committee's last visit, and the fact that they are overseen and evaluated by the civil regulators adds reassurance.

Carbon-14

27. It will be recalled that signification levels of carbon-14 in NNPP wastes were identified as a result of the examination of waste treatment plant resins transferred from Devonport to AEAT Winfrith for removal of chelates (chemical substances which, by bonding to metal ions, can mobilise radionuclides within waste, thereby making them unsuitable for disposal to Drigg). The carbon-14 problem has the potential for significant effects on both ILW and LLW management at Devonport.

Low level solid waste

28. Both the dockyard and naval base have made impressive progress in reduction and minimisation of LLW at the point that the wastes are transferred from the submarines to Health Physics control. While RWMAC is aware of the difficulties in achieving waste reduction at source, nevertheless the Committee believes there is scope for incorporating waste minimisation and reduction issues into submarine operational management objectives to a greater extent than has been achieved to date.

29. The BNFL site at Drigg has limits on disposals of carbon-14 waste, which could potentially have been exceeded in previous consignments of Devonport LLW containing undetected carbon-14. The carbon-14 issue caused BNFL, as operators of Drigg, to place an embargo on all disposals of LLW from Devonport in January1999. This has still not been lifted.

30. At the time of the RWMAC visit, about 150 drums of LLW were in store on the dockyard site, awaiting transfer to Drigg. The Committee was told that this represented 60-70 per cent of capacity and that the limits on storage within the site safety case would be exceeded by the end of April 2001. DRDL, together with the other NNPP sites and MoD, are working to try and establish the magnitude of the problem and to have the embargo lifted, so that the drums can be moved off-site. At the time of preparation of this report, RWMAC was under the impression that the issue was close to resolution, and that most NNPP LLW streams would be able to go to Drigg, under variations to the existing authorisations (already issued by EA in February 2001), in the near future.

31. Some waste streams are likely, however, to contain levels of carbon-14 which are incompatible with Drigg limits, and which will, therefore, have to be managed as ILW (see paragraphs 35-36).

Intermediate level waste storage

32. At the time of the last RWMAC visit to Devonport in November 1994, the Committee noted that resins were stored in Resin Catch Tanks (RCTs) in a shielded enclosure and in modified Magnox spent fuel transportation flasks standing in the open air. In its report, the Committee commented that these arrangements were not ideal; proposals to build the new D151 store were, therefore, welcomed.

33. RWMAC Members visited the new store during the March 2000 visit. The store appears well designed for its purpose, although the delays in its commissioning have meant that some RCTs and Magnox flasks are still being used for the form of resin storage criticised in the last report. A substantial programme to decant ILW resins from the RCTs into Resin Storage Vessels (RSVs) designed for placement in silos within the new store is required. DRDL have such plans in place.

34. These plans are, however, dependent on the availability of facilities which are also used to support submarine decontamination processes prior to de-fuelling, and decanting can, therefore, only be accomplished when the refit programme allows. RWMAC remains of the view that the current arrangements for storing ILW resins are less than ideal, and is disappointed that the issue has still to be fully resolved.

35. The detection of carbon-14 potentially causes substantial problems for DRDL's radioactive waste management strategy. Both the D151 store itself, and the waste containers, are based on the assumption that the main contaminant within the waste was cobalt-60. This has a half-life of 5.3 years, so it was assumed that with a period of about 25 years (about five half-lives), the activity of the cobalt-60 would have decayed to a level which would enable the waste to be classified as LLW for disposal to Drigg. This view provided the basis for information given to the LLC and the local population. It is clear, however, that identification of the carbon-14 (half-life 5,730 years), potentially renders this strategy invalid.

36. DRDL is working to try to establish the magnitude of the carbon-14 problem in relation to its stored wastes. The amount of carbon-14 may vary from container to container and could, in some instances, be close to the ILW activity limit. The whole DRDL storage and disposal strategy could, because of the possibility that some ILW will not decay to LLW within container or store design lifetimes, be in jeopardy. The Committee is, however, satisfied that the company is taking steps to address the problem.

Tritium

37. Enhanced submarine reactor systems, although with the major concepts designed as long as 20 years ago, are now entering service in the new Vanguard Class vessels. Associated improvements include developments in reactor chemistry and use of primary circuit materials, which, as well as resulting in lower doses to crew and dockyard workers, also give rise to much lower quantities of cobalt-60 (the most radiologically significant radionuclide arising from the reactor circuits). This new design has also eliminated the discharge of radioactive liquids, both at sea and alongside for routine repair, through the incorporation of an internal make-up and discharge (MUD) tank. However, this, in turn, has led to an increase in the amount of radioactive material that must be handled when the submarines come into Devonport for refitting and refuelling work.

38. For these reasons, DRDL requested, in its May 2000 disposal authorisation variation application, for the limit on liquid discharges of tritium to be increased from 120 to 800 GBq per year based on the new Vanguard submarine requirements. An increase of this magnitude is, at the very least, presentationally very significant, although its radiological implications, in terms of dose to the critical group, may be small. Nevertheless, it may be expected that the public consultation, currently (March 2001), being undertaken by EA on the DRDL application will generate considerable debate about the increase in tritium discharges sought. RWMAC would not wish to pre-empt the content of that debate, but believes that the following points may be relevant:

- operational requirements for the UK's nuclear submarines, consequent to national defence policy, necessitate the refitting of the Vanguard Class submarines, part of the process of which involves the removal of tritium-contaminated effluent;

- it may be expected that EA will require DRDL to demonstrate that the option selected for managing the effluent (by "discharge and disperse") is the BPEO.

39. The logic of these points is that, on the one hand, Government defence policy has set the agenda for the DRDL application. On the other, some key objectives of EA's consideration of the application appear to be defined by Government environmental policy. For the present (until on-board tritium arisings can be significantly reduced), DRDL's management of tritium, and, depending on scrutiny of the BPEO exercise, its discharge to sea, are inevitable consequences of UK defence policy. In principle, any dislocation between defence and environmental policy, one of the problem areas that "joined-up government" is designed to address, might have been recognised earlier, although practical decisions viz a viz OSPAR were doubtless very difficult.

40. RWMAC has been advised by HSE that the nature of tritium means that its removal from liquid wastes can only be achieved by large scale plant. Its generation, in the case of submarines, might, over the longer term, be reduced by a change to the chemical composition of the primary reactor coolant, but this will take years to trial and assess, whereas the application needs to be determined by the beginning of 2002 to allow the docking of the first Vanguard Class submarine.

Submarine spent fuel

41. Spent fuel removed from submarines in the Devonport Submarine Refit Complex is ultimately intended to be transported by rail to Sellafield where it is stored in an engineered pond. Devonport has a pond of its own for storage of the fuel cores pending their transfer.

42. At the time of the visit, however, no spent fuel had been removed from Devonport during the past two years. Two submarines still needed to use the current SRC facility as part of their planned refuelling. As the site pond was nearly full, there appeared to be a bottleneck that could only be cleared by the transfer either of some of the existing stored fuel out of Devonport or of the fuel immediately on its removal from submarines.

43. Since the visit took place (in summer 2000), RWMAC understands that DRDL has been able to develop a vehicle transporter which allows the NTL3M type spent fuel transport container to be lifted onto rail wagons. This has enabled some fuel to be removed from the Devonport pond.

44. DRDL will only be able to use the new UFF type container (approved for use in November 2000) when the new Vanguard facility becomes operational. Nevertheless, the pond itself should be decanted of spent fuel as early as is practicably possible.