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Radiation risk at Trident site in Derby - CND report

Rolls Royce Marine Power Operations Ltd, Derby produces the highly enriched uranium fuel rods for use in Royal Navy submarine pressurised water reactors. They also build and maintain these reactors.

All of this occurs on the one site - Raynesway, close to the centre of Derby.


In 1946, following close collaboration throughout the Second World War on designing, developing and building nuclear weapons, the U.S. severed all nuclear links with the U.K. and decided to proceed with its nuclear weapons programme on its own. The U.S. legislative passed the McMahon Act (The Atomic Energy Act of 1946) which prohibited the exchange of any nuclear weapons information or materials with any other nation.

The situation changed some years later with the passing of the 1954 Atomic Energy Act. This allowed, amongst other things, co-operation on the development of nuclear weapons delivery systems. In 1958 this Act was further amended to permit co-operation on nuclear weapons design, development and manufacturing capability. It also would allow the U.S. to transfer nuclear materials for research, development, or use in nuclear weapons and nuclear-powered submarines. This amendment to the 1954 Atomic Energy Act now acts as the legal foundation upon which all nuclear weapons cooperation between Britain and the U.S. is based.

To formalise matters Britain and the U.S. signed the 1958 US./UK Mutual Defence Agreement. This Agreement is periodically updated to accommodate new weapons developments and to permit further transfers of information and material. In almost forty years the Agreement has been amended six times, the last being May 1994.

Whilst the Agreement serves as the cornerstone of all U.S./U.K. co-operation on nuclear weapons matters it has received little scrutiny from either the U.S. legislator or the U.K. parliament. Many details of what goes on under the auspices of the Agreement remain secret.

Article II of the 1958 Agreement involves the exchange of information on all aspects of nuclear weapons including their design, development and production. It also allows both countries to swap information in order to assist with:

Article III of the Agreements governs the transfer by sale, barter or loan of materials and equipment for use in the U.K. nuclear weapons programme, including:

What has this to do with Derby?

The 1958 Agreement, as amended, allowed for the supply of a complete S5W nuclear propulsion plant as then being used by the US Navy, and the transfer of the basic reactor technology from the US company Westinghouse to Rolls Royce. This would allow Rolls Royce to design, manufacture and maintain submarine reactors and produce the fuel rods as well i.e. they would become totally self sufficient in all the technologies involved in submarine nuclear reactor development.

A special company was created known as Rolls Royce and Associates in 1959 with the Associates being Vickers, Foster Wheeler and Babcock and Wilcox.

At the Derby plant Rolls Royce built a submarine reactor fuel fabrication plant, the necessary engineering facilities to build submarine reactor plants, a zero-power reactor known as Neptune as well as offices and labs.

At Dounreay in Scotland they built "Vulcan" - a facility for testing life-size naval nuclear reactors. This facility went critical with the first entirely British naval nuclear reactor in 1965.

Forty years later

Forty years on Rolls Royce are still building submarine nuclear reactors and fuel cores for use by the Royal Navy at their plant in Derby.

They have designed, built and helped to maintain the more than twenty-five nuclear powered submarines that the British Royal Navy has deployed to date. This includes the submarine launched ballistic missile submarine, Trident.

The Associates were bought out some years ago now and the company is a solely owned subsidiary of Rolls Royce plc. In January of this year Rolls Royce and Associates changed its name to Rolls Royce Marine Power Operations Ltd.

According to their last available set of account for Rolls Royce and Associates (31 December 1997) rather modestly stated that "The principal activity of the Company during the year was the provision of naval reactor systems..."

Rolls Royce, plc in their last accounts and annual report (1997) state that "Rolls Royce reactor plants power the Royal Navy’s nuclear submarine fleet..."

Rolls Royce Marine Power Operations will continue to supply fuel cores for all naval nuclear reactors currently in existence, this includes Trident. They will also supply the new generation of submarine nuclear reactor for the Astute class of 'hunter-killer' submarines. This reactors is intended to last for the submarines entire lifetime and require no refuelling.

Backup documentation

The below 'highly classified' document fell into our hands. It explains in detail exactly what goes on at Rolls Royce, Derby and was prepared for a briefing of the Nuclear Safety Advisory Committee early last year.

In order to protect the source this document has not been provided in its totally original form, but has been retyped.


Security Note

The detailed design and the manufacturing processes used in the production of UK naval reactor cores are subject to restrictions under the Official Secrets Act. Members of NuSAC are asked to consider this when examining this summary paper in advance of the presentation to the Committee on 12th March, 1998


by Ian Gray and Ian Evans, RolIs-Royce aud Associates Ltd, Derby

1) Introduction

ln 1954, the first nuclear powered submarine, the USS Nautilus was launched by the US Navy. This transformed the submarine concept from a slow under water vessel with limited endurance to a high speed warship capable of many weeks of submerged operation. The achievement was not lost on the UK government of the day which instituted a nuclear submarine development programme The programme received a significant boost in 1958 when the US/UK bilateral Agreement for Cooperation on the uses of Atomic Energy for Mutual Defence Purposes was signed.

Amongst other things, the Agreement provided for the supply of a complete S5W propulsion plant as fitted to the then latest US Skipjack subjuarine class and also the transfer of the basic reactor technology and the manufacturing expertise from Westinghouse to Rolls Royce. Rolls-Royce and Associates (RRA)was formed in 1959 with the "Associates" being Vickers, Foster Wheeler and Babcock & Wilcox. The Associates' shareholdings were subsequently bought out and RRA is now fully owned by Rolls-Royce plc. The first UK nuclear submarine, HMS Dreadnought, was launched in 1960 and incorporated the American supplied S5W plant.

Offices, laboratories, a zero-power reactor (Neptune) and a core manufacturing plant (Nuclear Components Division) were constructed on the RRA site in Derby. The core plant was a close copy of the original Westinghouse manufacturing facility in the US. The naval reactor test facility, Vulcan was established adjacent to the UKAEA fast reactor site at Dounreay and went critical with the first all British reactor core (Core A) in 1965.

Since that time RRA has developed a series of cores and reactor designs based on the original US technology, but now very different from the plants which power the US Navy.

Following the original transfer, there has been only limited interchange between the US and the UK on naval reactor technology and the current reactor plant and cores may be regarded as essentially UK designs.

2) Core Design

The evolution of the reactor plant has always been driven by safety and availability considerations with the core life showing a progressive upward trend with successive designs. For example, the latest core design (Core H) will allow the new Astute Class, previously known as Batch 2 Trafalgar, to operate without refuelling for the whole of the vessel lifetime whereas the early cores were exhausted after a few thousand hours of full power operation. The Ministry of Defence requires that, where practicable, the safety of its naval reactors and the associated processes and activities be to the same high standards as are adopted in the UK civil nuclear industries.

The operating parameters for naval reactors are significantly more onerous than those of civil plant in that they must be able to respond to rapid changes in power demand over the whole life of the core and be resistant to possible externally imposed shock loadings. A measure of the robust nature of the core generic design is the total absence of fuel failure during the whole of the UK naval reactor programme. This includes both operational vessels and the prototype cores which are subject to demanding test conditions in the Vulcan facility.

The design of the UK Naval PWR plant differs in a number of significant respects from its civil counterparts. The fuel elements incorporate Zircaloy and enriched uranium with a Zircaloy clad. Burnable poisons are incorporated to assist reactivity control through life. The core is of modular construction. Reactor reactivity control and shutdown functions are achieved with control rods. The overall reactor temperature coefficient is negative and the core is designed to be self regulating and able to follow flexibly turbine steam demands without the need for rod movements.

3) Core Manufacture

The Rolls-Royce Core Manufacturing Plant was built in the late 1950s to the original Westinghouse design. Due to the nature of the processes and the relatively small throughput, manufacture is not highly automated. However, design tolerance requirements have become much more demanding and inspection techniques are highly sophisticated and where appropriate, automated to meet very demanding quality controls.

The essence of the manufacturing processes involves incorporating enriched uranium with Zircaloy, reducing the fuel material to the required dimensions and cladding the fuel with Zircaloy to form elements which are then assembled into core modules. Core components containing burnable poison are manufactured in a similar manner to that of the elements. In addition, the control rods and all the non-fuelled Zircaloy core components are fabricated within the Plant. The Plant also includes the capability for the manufacture of steel components required for control rod mechanisms, valves and other specialist components of the reactor plant.

The methods of core manufacture are dominated by the requirements for the fabrication of highly chemically reactive materials and the overiding need to maintain close manufacturing tolerances of the complex components and assemblies. In many respects, there is much in common with industrial processes which, for example, melt and fabricate titanium alloys for the aerospace industry.

The manufacturing tolerance requirements also impinge upon the component nuclear performance and quality control measures are required which measure and confirm that reactivity and poison disposition match the design intent. Confirmatory measurements of core physics performance may be conducted in the Neptune zero power test reactor. The high power density of naval cores and the tight dimensional tolerances require that each core is individually characterised prior to entering service. The process of confirmation of core characteristics continues throughout life to ensure that safety parameters are correctly set as the core is progressively burnt up.

The nature of the fuel demands working practices which minimise the risk of criticality accidents, the control of dose uptake by the workforce and releases to the external environment. Manufacturing activities which may release airborne contamination are as far as possible undertaken within enclosures designed to contain the local process environment. The hazards are mainly due to alpha emitters. Ventilation extract systems are employed which incorporate absolute filtration, discharge monitoring and alarms. Movements of fissile components within the plant are governed by strict administrative controls augmented by equipment designed specifically to assist the workforce and to eliumate criticality hazards.

There is recognition and control of sources of moderating materials such as water, lubricating and hydraulic oils and polyethylene.

Storage of completed fuel assemblies prior to shipment to the Naval bases or to the Vulcan test facility is carefully controlled. Each module has its control rod locked in place and the storage facility takes account of accidents which could change the fuel configuration and introduce moderator.

Scrap materials and arisings are as far as practicable recycled within the facility. The nature of the materials handled requires that strict accountancy measures are adopted for all fissile materials on the site. Periodic audits of the inventory of fissile material are undertaken by the Ministry of Defence.

4) Regulation

All activities are subject to civil regulation by the Nuclear Installations Inspectorate. Arrangements are in place to discharge the Generic Licence Conditions in a manner similar to other civil licenced sites. The Neptune zero power reactor is subject to separate civil licencing by the NII. The Vulcan Test facility remains subject to regulation by the MoD. A Safety Committee, chaired by the General Manager of the Nuclear Components Division, operates as required by the Site Licence. The liquid and gaseous discharges from the plant are authorised by the Environment Agency. The disposal of solid low level waste material is undertaken at the Rolls Royce licenced disposal site at Crich in Derbyshire. The BNFL Drigg disposal site is not used for wastes from the manufacturig processes. Transport of fuel components to naval sites is regulated by the Department of Transport which approves both the fuel containers and the transport arrangements.

Standard MoD approved security is maintained on the site with the whole workforce subject to security vetting by the Ministry of Defence.


Her Majesty's Nuclear Installations Inspectorate Quarterly Report for 1 January to 31 March 1999

An extract

Rolls Royce Marine Power Operations Limited has an on-site emergency but none for dealing with off-site consequences from an accident.

An exercise of the on-site plan took place on 30 March, 1999. The report of HMNII was not good.

"All nuclear licensed sites conduct an annual demonstration exercise of the approved emergency arrangements, witnessed by HMNII. Such an emergency exercise was held on 30 March, at which the site response to a challenging scenario was exercised. The licensee demonstrated prompt mustering and accountancy of missing persons. However, the licensee was unable to demonstrate adequate contamination control arrangements when managing the emergency response. Also the licensee did not integrate the senior officers of the participating emergency services to a sufficient degree. Consequently the Inspectorate have requested that the licensee resolve these issues and undertake a repeat demonstration exercise within a timescale to be agreed with the Inspectorate." [emphasis added]

For a full copy of this report see: NII Derby Report

Original report on British CND website

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