Research reactors

Many institutions worldwide installed small reactors in support of research and development programmes. Research reactors provide a wide range of training, research, commercial and nuclear power programme support functions from nuclear reactors which are generally not used for power generation. Their output (neutron beams) is used for non-destructive testing, analysis and testing of materials, production of radioisotopes, research and public outreach and education. The UK has had more than 30 research reactors since the 1950s (Table 1.3) but, like all countries, it has shut and decommissioned almost all of them. Its last remaining one Consort, owned and operated by Imperial College London, shut down in December 2012.

Many of these reactors used novel fuels and decommissioning them requires programmes of research to determine suitable ways of managing their wastes. The Nuclear Decommissioning Authority (NDA) in the UK has a special programme examining options for these so-called exotic fuels (NDA, 2012a). For example, such materials held at Dounreay in Scotland include:

• unirradiated plutonium-bearing fuels consisting of plutonium, mixed uranium and plutonium oxide and mixed uranium and plutonium carbide fuels;

• unirradiated high enriched uranium fuels consisting of uranium oxides, uranium metal, uranium alloy, uranium tetrafluoride, uranium hexafluo­ride and other miscellaneous enriched uranium fuels;

Table 1.3 Current and former research reactors in the UK

Facility name

Thermal

power

(kW)

Type

Status

Criticality

date

Bepo

6,500.00

Graphite, air

Decm

01/01/1962

Berkeley Zero Energy

1.00

Graphite

Decm

14/04/1966

Daphne

0.10

Heavy water

Decm

01/01/1962

Dido

26,000.00

Heavy water

Decm

07/11/1956

Dimple

0.10

Pool

Decm

01/01/1962

Dounreay Fast Reactor

65,000.00

Fast breeder

Shut

01/11/1959

Dounreay MTR

22,500.00

Heavy water

Decm

01/05/1958

Dragon

20,000.00

He cooled

Decm

01/01/1964

Gleep

50.00

Graphite

Shut

18/08/1947

Hazel

0.00

Homog (l)

Decm

01/01/1957

Hector

0.10

Zero power htd

Decm

01/03/1963

Hector

0.10

Graphite CO2

Decm

10/03/1963

Herald

5,000.00

Pool

Shut

10/10/1960

Hero

3.00

Graphite AGR

Decm

01/06/1962

Horace

0.01

Crit assembly

Decm

01/05/1958

ICI Triga Reactor

250.00

Triga mark I

Decm

01/08/1971

Consort, Imperial College

100.00

Pool

Shut

04/09/1965

Jason

10.00

Argonaut

Decm

30/09/1959

Juno

0.10

Crit assembly

Decm

01/03/1964

Lido

300.00

Pool

Decm

01/09/1956

Merlin

5,000.00

Pool

Decm

01/07/1959

Neptune

0.10

Pool

Oper

03/01/1963

Nestor

30.00

Argonaut

Decm

01/01/1961

Pluto

26,000.00

Heavy water

Shut

25/10/1957

QMC UTR-B

100.00

Argonaut

Decm

10/08/1964

The Univ Research Reactor

300.00

Argonaut

Decm

07/07/1964

UTR-300

300.00

Argonaut

Decm

01/06/1963

Vera Nuclear Assembly

0.10

Crit fast

Decm

01/01/1961

Viper

0.50

Fast burst

Shut

26/05/1967

Vulcan

0.00

PWR

Shut

01/01/1961

Windscale AGR

120,000.00

Graphite AGR

Decm

09/08/1962

Zebra

1.00

Crit fast

Shut

01/12/1962

Zenith I

0.50

Graphite CO2

Decm

01/12/1959

Zenith II

1.00

Graphite

Decm

01/03/1972

Zephyr

0.00

Crit fast

Decm

01/01/1954

Zeus

0.10

Crit fast

Decm

01/01/1955

Note: Deem = decommissioned.

• irradiated fuels, comprising oxide and carbide fuel consisting mainly of prototype fast reactor (PFR) fuel and the HELIOS material that was irradiated in experimental work.

Credible options for management of these fuels in the near term have been identified but significant R&D may be needed to identify routes to perma­nent disposal (NDA, 2012a).

Many research reactors use highly enriched uranium (HEU) which, because of its potential to be used in unauthorised nuclear weapons, is a significant security threat. As of 2011, approximately 70 tonnes of HEU is being used in civilian power and research programmes in roughly 30 coun­tries. Securing and eliminating stocks of HEU is necessary to decrease the risk that terrorist groups could use this material to create a nuclear explo­sion. Some 244 research reactors are in operation or temporarily shut down across 56 countries, while a further 424 reactors have been shut down or decommissioned, and five are planned or under construction.

Many of the research reactors that have been shut down, but not decom­missioned, have spent HEU fuel on-site. Threat reduction programmes aimed at reducing the amount of HEU at civilian facilities have been in place since 1978, when the USA initiated the Reduced Enrichment for Research and Test Reactors (RERTR) programme. Russia also initiated a programme to reduce enrichment at Soviet-built research reactors outside the Soviet Union. In the past 25 years, many countries have cooperated with the RERTR programme or initiated their own similar programmes. In 2004, the US Department of Energy (DOE) launched the Global Threat Reduction Initiative (GTRI) which the IAEA, Russia, and others have since joined. Among its goals, the GTRI seeks to ‘minimize and eventually eliminate any reliance on HEU in the civilian fuel cycle, including conversion of research and test reactors worldwide from the use of HEU to the use of Low Enriched Uranium (LEU) fuel and targets’ (Office of Global Threat Reduction, US National Nuclear Security Administration, http://nnsa. energy. gov).

In addition to converting research reactors that use HEU fuel, the RERTR programme is also working on the conversion of medical isotope producers that use HEU targets in their reactors. The programme includes some of the largest producers of medical isotopes, located in Belgium, the Netherlands and South Africa. Besides converting facilities to use LEU fuel, there have also been efforts to consolidate fresh and spent HEU fuel at a smaller number of relatively secure locations. This has involved remov­ing the fuel, mostly to the US and Russia, from other countries, as well as consolidating the fuel within countries. US programmes in this area have all been subsumed under the 2004 GTRI initiative. Together, the two pro­grammes have returned over 2,000 kg of spent and fresh HEU fuel to the USA and Russia since 2004.

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