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The  United  Kingdom  Atomic  Energy  Authority (UKAEA) today announced the final  decommissioning  of the first reactor in Western Europe. GLEEP - the Graphite Low Energy Experimental Pile - first went critical in 1947 and was shut down in 1990.

The  contract  for  its  dismantling  has  been let to Renfrew based Mitsui Babcock.  Decommissioning is planned to be completed by autumn 2004.  GLEEP  played  a  key  role  in  the development of civil nuclear energy in Britain.  It  was used in investigations into how to make a nuclear reactor work including the early design and development of Magnox nuclear fuel used in  commercial generating stations operating today. It was later used as an international standard for testing materials for other nuclear reactors and for calibration.   After 43 years of operation, GLEEP was shut down in 1990 and in 1994/95, the fuel rods and control rods were removed.

The  final  phase  of  GLEEP's decommissioning and the complete removal and dismantling  of the reactor will allow the removal of two hangars and other associated  buildings,  freeing  the  eastern  end  of  the Harwell site in Oxfordshire  for  new  development.   Total cost of the decommissioning and other demolition work is around £10 million.

Dr  John McKeown, Chief Executive of UKAEA commented:  "The decommissioning of  GLEEP is a landmark in the environmental restoration of Harwell and the transformation  of  the  site  into  an international business centre.  The removal  of  GLEEP, together with other redundant buildings at the front of the  Harwell site, will pave the way for delicensing and development of the eastern area of the site."

Managing  Director  of  Mitsui  Babcock, Europe, Iain Miller added: "We are extremely  pleased to be awarded this contract. We have worked closely with UKAEA  and  sub-contractors  to  develop  a  'best  practice'  solution for decommissioning  GLEEP  and  restoring  this  part  of the Harwell site for development."

Re-development  of  the site began with the launch of Harwell International Business  Centre in 2000.  The Gemini office block was built in partnership with  ProLogis  Developments  Ltd  in  2001.   By  releasing  more land for unrestricted  use,  it  is  hoped  to  create a thriving hub of science and technology  on  the  Harwell-Chilton  campus.   The new Diamond Synchrotron being  built  on  the  campus  which will create 500 science and technology jobs.

GLEEP was the first reactor in Europe and was operational from 1947 - 1990.  Generally operating at 3kW, GLEEP was used for initial investigations into how a reactor would work and later as an international standard for materials testing and calibration.  GLEEP was closed in 1990.

UKAEA is working to restore the environment of its Harwell site, removing the nuclear legacies and releasing the land for unrestricted use as a science and technology park.

UKAEA has devised a comprehensive plan to develop Harwell so that it can provide quality accommodation and facilities for companies working in the fields of science and technology - from start-up companies to fully developed international organisations.  The site has an overall development ceiling of 2.5 million sq ft of new and existing space.

Harwell International Business Centre combines an international reputation for scientific excellence with a business environment for the 21st century. The Centre is one of the UK's premier locations for commercial industry working in the fields of science and technology.

Organisations based at Harwell service customers in science, government and commercial sectors worldwide. They include The Medical Research Council, Harwell Dosimeters, Harwell Scientifics, Oxford Drying Restoration Services, Amersham, Regenesys Technologies and REVISS Services (UK).

Background
GLEEP (Graphite Low Energy Experimental Pile) was the first reactor in Europe and was built in 1946. Generally operating at 3kW, GLEEP was used for initial investigations into how to make a reactor work and later used as an international standard for materials testing and calibration. After continuous operation for 43 years, GLEEP was closed in 1990. Until the fuel could be removed, extra control rods were inserted into the core.

Objectives
To take GLEEP to Stage Two decommissioning including the removal of fuel, control rods, and other external equipment, leaving the reactor in a state of care and maintenance until further decommissioning can be implemented.

Key challenges
Removal of 11,500 spent fuel rods. GLEEP had only been refuelled once in 1960, so experience of fuelling/defuelling was very limited.

Solution
Stage One decommissioning, the removal of spent fuel, took place in 1994. This accounted for 99% of the inventory of radioactive materials in GLEEP.  In order to defuel the reactor a specialist remotely operated crane was designed and commissioned. The fuel removal machine had a 4-point lift crane, which moved on rails between the graphite core and the bio-shield. Attached to the crane was a fuel retrieval unit. Fuel was discharged by manual rodding from the opposite face of the core, which loaded the spent fuel into trays in the retrieval unit. The retrieval unit then posted the fuel through the bio-shield into a shielded cell where it was manipulated into storage cans and despatched to the waste store.

The control rods from the core and other external equipment were removed in 1995.  Fuel being retrieved during Stage One decommissioning.

Outcome
All fuel elements were removed and despatched for storage in 7 months.
Cross-department working enabled the UKAEA team to enhance productivity and efficiency completing defuelling within time and budget, and resulting in minimal dose rate to operators.
GLEEP remains isolated receiving care and maintenance in Stage Two decommissioning.

Stage Three decommissioning is planned for 2003-2005.