Hunterston

Halcrow has successfully delivered the design for two of the UK's most modern Intermediate Level Waste (ILW) Stores, Hunterston 'A' and Hinkley Point 'A'.

Hunterston 'A' is the first in a series of stores and the design may be replicated across sites. Working closely with clients British Nuclear Group, Halcrow was able to develop value engineering for the design of Hinkley Point 'A' to deliver higher levels of cost effectiveness. Working closely with the contractor in an alliance allowed improved buildability and delivered further client gains.

	Multi-disciplinary design services		Safety case led design
	Interface management		Building longevity
	Designed for buildability		Design excellence
	Responsive to customer requirements		Proactive team partner
	Innovation		Value Engineering

The intent for the store is to provide a passive, secure, dry, robust store and create an environment which keeps the waste packages in such a condition such that they will meet the Nirex specifications for export to a repository at the end of the storage period. Once operational, internal maintenance of the vault area will not be practical, due to radiation levels, hence the requirement for a low-maintenance durable structure.

Case history
The Hinkley Point 'A' Nuclear Power Station was shut down in May 2000. The Intermediate Level Waste (ILW) Store will contain intermediate level waste arising from the operation and decommissioning of the station. The building comprises a heavily shielded concrete vault where the waste will be stored in stainless steel containers, and a service area which will house the crane used during vault filling and emptying. The reinforced concrete structure is fully enclosed within aluminium cladding to provide an aesthetic finish, additional protection from normal environmental effects and to maintain the internal environment of the vault within specified temperature and humidity limits.

Halcrow is providing civil / structural and building services consultancy services to the Alliance formed by British Nuclear Group, Halcrow, Weir Strachan & Henshaw and Nuttall to deliver the new facility to the Client, Magnox Electric, in early 2008. The design is safety led and the pre-construction safety report (PCSR), supported by Halcrow's design substantiation reports, has been approved by the Independent Nuclear Safety Assessor. The detailed design stage of the ILW Store is also complete. A detailed internal environment study using numerical simulation techniques was completed during the early stages of the project. This analysis was used to assess temperature variations for structural design and condensation risk within the vault during the 100 years life of the facility.

The Hinkley Point store is very similar to the store at Hunterston and the experience gained at Hunterston has been of significant benefit to the project. Through a value engineering exercise, promoted in conjunction with our client, the Hinkley facility has been significantly streamlined in certain areas to allow substantial cost reductions to be gained; whilst still maintaining the full integrity and intent of the facility. Analysis and design techniques have also been enhanced by developing graphical interfaces to manipulate analysis and design output into a graphical format for reinforcement detailing. This has increased efficiency in design and delivered substantial savings in design time.

Halcrow has also been responsible for the building services design incorporating: mains power supplies, fire alarm systems, vault monitoring and vault and service area ventilation systems. Design co-ordination, across the design teams based in three Halcrow offices and with the Crane designer, Weir Strachan and Henshaw, has been a challenge very successfully met during the design period. Significant interfacing with civil contractor, Nuttall, has also been incorporated during the design development ensuring high levels of buildability and a cost effective design.

On the successfully achieving the INSA approval of the PCSR, Magnox Electric ILWS Alliance project manager Neil Lock complimented the team stating that to accomplish this milestone "effectively ahead of programme, is a fantastic achievement".

Halcrow has a unique level of expertise in the development of modern waste stores in the UK and can use this knowledge to deliver value and certainty in the development of future projects.

Skills
	Nuclear process plant		Materials technology
	Mechanical and remote handling		Seismic engineering
	Building services		Blast and impact
	MEICA / M&E services		Fire engineering
	HVAC		Wind engineering
	Radiological / shielding		Thermal engineering
	Civil / structural and architectural design		Numerical Analysis
	Geotechnics and foundations