Harwell Timeline
from the early years
to the present day
In Summary
World-class excellence
The Harwell site has been a centre for advanced science and technology for more than
65 years. In that time it has made enormous contributions to the development of nuclear
energy, and many other major scientific and technological advances.
It was in 1946 that a former RAF station in Oxfordshire became
the Atomic Energy Research Establishment (AERE). By 1947
1,000 people were working on the site. From the start Harwell
established a name for excellence.
UKAEA then took responsibility for decommissioning and
site restoration. UKAEA entered another new phase in 2005
when it began operating as a contractor to the newly created
Nuclear Decommissioning Authority (NDA).
Harwell produced many nuclear firsts: the first reactor in
Western Europe, the first large reactor to be constructed
outside the USA or USSR, and the UK’s first fast reactor.
In 2009 Research Sites Restoration Limited (RSRL), successor
to the AERE (albeit with a very different mission) was set up
as a subsidiary of UKAEA Ltd. RSRL was the site licence
company responsible for decommissioning and clearance at
Harwell and its sister site at Winfrith, under contract to the
NDA. In October 2009 UKAEA Ltd was sold to Babcock
International Group. Competition to appoint a new parent body
organisation for RSRL and Magnox began in 2012. Cavendish
Fluor Partnership was announced, the preferred bidder and
share transfer happened on 1 September 2014. RSRL became
known as Magnox in Spring 2015.
The site has adapted to changing circumstances, moving
from reactor research and development into non-nuclear and
commercial research, and then to decommissioning, waste
management and site restoration. Throughout these periods
of change, Harwell’s reputation for scientific and engineering
excellence has remained as strong as ever.
The organisation has undergone many changes, operating
under various names and management structures. In 1954,
Harwell joined other sites to become the United Kingdom
Atomic Energy Authority (UKAEA). UKAEA was restructured
in the 1990s, following the launch in 1989 of AEA Technology
(AEAT) as its commercial arm, which was privatised in 1996.
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Today large sections of land have been removed from nuclear
regulation, paving the way for the ongoing expansion of the
Harwell site as a science, innovation and business campus
under the banner of Harwell Oxford, and a new chapter in
Harwell’s unique history.
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1 RAF buildings as seen in 1947
2 GLEEP Reactor in operation 1983
3 An early morning take off by a Handley Page Halifax 1944
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4 Research Sites Restoration Ltd was formed 2009
5 Aerial shot of DIDO and PLUTO Reactors 1967
6 Aerial shot of Harwell site 1996
The Early Years
Dawn of a new age
The 1950s at Harwell were years of rapid growth. As early as 1953 more than 6,000
people were employed on site. The nuclear power industry was growing and in need
of data upon which to base the design of its reactors and associated fuel cycle plant.
Harwell provided much of that essential information.
Reactor construction
Fourteen experimental reactors were built at Harwell.
GLEEP and BEPO were the first two to be constructed,
initially to provide data for the Windscale reactors. GLEEP
ran for an astonishing 43 years (1947-90) and was finally
decommissioned and dismantled in 2005.
The more powerful BEPO, the first large reactor to be
constructed outside North America or the USSR, was a direct
predecessor of later gas-cooled power reactors. Built in 1948,
it ran for 20 years.
A dozen other reactors soon followed. The most important
were two large materials testing reactors, DIDO (1956) and
PLUTO (1957), which played crucial parts in the development
of later power reactors, as well as providing large quantities
of radioactive isotopes for the medical industry. Both were in
operation until 1990.
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Several zero and low energy experimental reactors were built,
including ZEPHYR and NEPTUNE. In addition, Harwell was
home to the DIMPLE and LIDO reactors. ZETA was built to
advance understanding of fusion power, work which later
moved to Culham, UKAEA’s fusion laboratory.
Research facilities
A range of other ground-breaking research facilities were built
to support the nuclear programme.
Harwell’s radiochemistry laboratories, opened in 1949, were
the most advanced in the world, allowing the safe handling of a
wide range of radioactive materials. Van de Graaff accelerators,
a Tandem generator and a cyclotron were built to probe into the
atom. Pioneering research continued in purpose-built chemistry,
chemical engineering and materials research laboratories, and a
post irradiation examination facility. Waste management facilities
were constructed to treat active and non-active solid and liquid
radioactive waste from these activities.
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1 GLEEP Reactor construction 1947
2 BEPO Reactor in operation 1962
3 Radiochemistry building 220 1950
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4 LIDO Reactor swimming pool 1956
5 Experimentation in ZEPHYR Reactor 1955
6 Liquid Effluent Treatment Plant (LETP) 1961
Harwell
1950s – 2000s
The Timeline 1950s – 2000s
Sir Winston Churchill
tours Harwell
1950
1960
1970
1951
1961
1971
1952
110 inch diameter
synchrocyclotron - Hangar 7
1962
1953
1963
1954
1964
1972
1973
1974
Margaret Thatcher
visits site
DIDO Reactor
Construction
HM The Queen and HRH
The Duke of Edinburgh
Isotope production unit
1955
1965
1975
1956
1966
1976
1967
1977
1968
1978
1969
1979
1957
PLUTO Reactor top
1958
1959
Tandem Van-de-Graaff
Generator is built
Cockcroft-Walton particle
accelerator – Hangar 8
Chemical Engineering
1950s 1960s 1970s
Following the establishment of AERE
in 1946 at RAF Harwell, GLEEP, BEPO,
ZEPHYR, DIDO, PLUTO and other reactors
are built. Radiochemistry laboratories and
other facilities are constructed. Sir Winston
Churchill tours the site in 1954 and HM The
Queen and HRH The Duke of Edinburgh in
1957. Tandem Generator is built in 1958.
The research programme is at its zenith,
some of it in converted RAF hangars. Early
research into fusion energy and fast reactors
takes place. Harwell begins to undertake
new roles in non-nuclear scientific research.
Harwell makes the transition from being
government-funded to a partly commercial
research organisation. Spin-off technologies
are used throughout industry in chemical
engineering, computer programming, oil
and gas exploration and many others.
It establishes a name for excellence in
safety research and environmental science.
1980
1990
1981
1991
1982
Intermediate waste store
1992
2000
2001
GLEEP decommissioning
2002
2003
1983
1993
2004
1984
Laser beams used in
laser isotope separation
Ground water treatment
plant before it was replaced
1994
Tandem Van-de-Graaff
Generator demolition
1985
1995
1986
1996
2005
2006
2007
50m long Harwell
Pipeline facility
1987
1997
DIDO and PLUTO in care
and maintenance
2008
2009
1988
1998
1989
Calorimetric surveys
– cold fusion
2010
1999
Chemical engineering
building 351 demolition
2011
RAF Water Tower
demolition
1980s 1990s 2000s
Laser beams are used to investigate aspects
of the basic science and technology of
laser isotope separation. The examination
of liquid flows of gas and sand for the oil
industry is carried out in the Harwell pipeline
facility. Scientists debunk ‘cold fusion’
claims through careful measurements.
AEA Technology is created in 1989 as a
commercial organisation, later privatised.
Harwell concentrates on the work of
decommissioning its nuclear plant and
disposing of waste. A major programme
of decommissioning begins. GLEEP, DIDO
and PLUTO reactors are closed down.
Redundant facilities are decommissioned.
Waste recovery and processing plant are
built. Harwell International Business Centre
is established in 1996.
GLEEP and the Tandem generator tower are
gone. 160 redundant facilities and buildings
are removed and historic chemical storage
areas cleaned up. DIDO, PLUTO and BEPO
are put in long-term care and maintenance.
In 2005 Harwell becomes a contractor to the
NDA. In 2009, RSRL was formed. By 2012
more than 1.6m sq ft of land is cleaned up and
approximately one fifth of the site delicensed.
The Middle Years
Applying expertise
By the late 1960s the nuclear industry was starting to mature; there was not the same
requirement for fundamental nuclear research. This led to decades of change, as
Harwell’s focus moved towards applied nuclear and non-nuclear research.
Diversification
Drawing on existing expertise, Harwell diversified into many
new areas, such as non-destructive testing, water desalination,
materials technology, and electronics. Applied nuclear work
included the development of nuclear instrumentation used
throughout the industry.
Elsewhere, medical, chemical engineering, computer
programming, battery and the offshore oil and gas industries
were among the fields to benefit from spin-off technologies
born at Harwell.
At this time the site was involved in several high profile
projects: detecting metal fatigue in Big Ben; measuring cosmic
ray doses on Concorde; contributing to the investigation into
the King’s Cross underground fire; carbon dating various
ancient artefacts, including the Winchester Round Table; and
debunking the discovery of so-called ‘cold fusion’.
Harwell was also prominent in the field of safety and
environmental science, establishing research centres to
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1MTR fuel rods cooling off in storage
pond 1982
2 Non-destructive testing 1975
deal with chemical emergencies, environmental safety
and environmental pollution, among others. In 1974 the
Government set up a new, expert advisory agency, the
Energy Technology Support Unit (ETSU). ETSU provided
policy support and programme management in renewables,
energy efficiency, clean coal, combined heat and power, and
sustainable transport.
The need for more powerful computers grew. In 1987, Harwell
achieved another first when it took delivery of what at the
time was the world’s most powerful computer, the CRAY-2
supercomputer.
Restructuring
In the 1970s, major restructuring meant some responsibilities
were transferred from UKAEA to other newly created
organisations. Even so, throughout the 1970s and 80s,
some 4,000 people were employed inside the Harwell
security fence.
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3 Desalination plant ‘Gibraltar’ 1973
4Great clock of Westminster
‘Big Ben’ 1983
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5 CRAY-2 Supercomputer 1987
6Scientists at work building 220 1976
7 Air sampling 1981
The Later Years
A time of change
The 1990s brought perhaps the biggest change of all. Reactors and laboratories across
UKAEA sites, including Harwell, ceased operations and attention was switched to
decommissioning and environmental restoration. Alongside decommissioning activities,
Harwell began to develop part of the site as an international business centre.
Era of decommissioning
With the ending of publicly-funded civil nuclear research
in the UK, all three of Harwell’s remaining reactors were
closed down. From now on, many of the engineers and
scientists who helped build and run Harwell’s experimental
facilities would concentrate their skills on decommissioning,
radioactive waste management, and site restoration.
The task of decommissioning began in earnest. During this
period UKAEA completed more decommissioning than any
other organisation in Europe.
After an exceptionally long operational life, GLEEP was
shut down in 1990, and the fuel, control rods and external
equipment removed. Major decommissioning work was
carried out on DIDO and PLUTO and by 1997 they were in
a condition suitable for long term care and maintenance,
pending final decommissioning.
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Many redundant facilities, including accelerators, R&D
laboratories and waste processing plant were also
decommissioned; new stores and plant were constructed
for the recovery and processing of waste.
Restructuring in the 1990s brought the number of
employees on site to around 2,500.
International business centre
UKAEA brought new commercial life to its former nuclear
sites with the creation of new technology parks, such as
the Harwell International Business Centre, since developed
as Harwell Oxford, a science, innovation and business
campus – now home to some 100 high-tech and research
organisations, employing 4,500 people.
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1 Building 220 decommissioning success 2000
2 Intermediate Level Waste (ILW) operations 2009
3 Waste Encapsulation Plant (WEP) 2008
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4 Chemical engineering building 351 demolition 1997
5 Waste Retrieval Machine 1 2001
6 Aerial shot of Harwell Campus 2009
The Present Day
2000 onwards
The new millennium saw the pace of decommissioning and restoration step up another
gear. In 2009 RSRL (now known as Magnox) was set up to complete the decommissioning
and site clearance. By 2012 large areas of the site had been delicensed and removed from
the controls of the Nuclear Installations Act and the security fence was realigned.
Decommissioning and restoration
Harwell’s decommissioning and restoration programme was
well underway by 2000. Harwell became part of the NDA’s
decommissioning programme in 2005.
‘temporary’ buildings from the 1950s. A number of facilities
including the DIDO, PLUTO, and BEPO reactors remain in
care and maintenance.
The NDA has brought even greater focus on disciplined
project management and coordination with other sites around
the country. Research Sites Restoration Ltd was created
in 2009 (now known as Magnox) to complete Harwell’s
decommissioning programme.
More than 160 unused buildings and research facilities have
been demolished, clearing more than 1.6 million square
feet of land. In 2011, Harwell’s site boundary fence moved
reducing the size of the secure part of the site. To date,
almost 18 hectares of land has been delicensed. This land
will eventually be de-designated by the NDA and form part
of the wider Harwell Oxford Campus.
Since the turn of the century, Harwell has completed
dismantling of the GLEEP reactor. The Tandem Generator,
many purpose built laboratories, a post irradiation examination
facility, and workshops have been decommissioned and
demolished. The extensive drain system throughout the site is
being cleaned and removed as necessary. Clean-up work has
removed a number of the RAF structures from the 1930s and
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Harwell’s history is one of constant change. What hasn’t
changed over the decades is its unrelenting focus on worldclass science and technology, which began with the birth of
the nuclear age in the 1940s and continues today.
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1 GLEEP pile during dismantling 2004
2 Tandem Van-de-Graaff Generator demolition 2005
3 Ground Water Treatment Plant 2007
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4 Retrieval Machine 2
5 RAF Water Tower demolition 2009
6 Medical and Health Physics Facility building 364 demolished 2010
For further information
Visit us at www.magnoxsites.com
Telephone us at 01235 820220
We have gone to considerable trouble to ensure that the facts presented in this brochure are
correct. We recognise that the achievements we have outlined are simply a snapshot of some
of the events at the Harwell site. They are not intended to be a comprehensive report of work carried
out over the decades.
Magnox is owned and operated by Cavendish Fluor Partnership (CFP) on behalf of the Nuclear
Decommissioning Authority (NDA).
The NDA works with CFP, the Magnox management team and other stakeholders to oversee the
delivery of programmes, building confidence amongst Government and others that the nuclear legacy
is being tackled effectively, safely and responsibly.
Harwell Site
Harwell Oxford
Didcot
Oxfordshire
OX11 0DF
Images reproduced by kind permission of the NDA photographic library.