United Kingdom United Kingdom · Harwell · 51.597, -1.293

GLEEP

GLEEP, a research reactor (graphite) in Harwell, United Kingdom, with 50 kW of thermal power, operated by Atomic Energy Research Establishment. Decommissioned, first critical in 1947.

It was one of the 46 research reactors the United Kingdom has had; 1 remains in operation today. It was the first research reactor in the United Kingdom to go critical. 4 graphite-moderated research reactors remain in operation today across 3 countries.

Country
United Kingdom
City
Harwell
Type
Graphite
Thermal power
50 kW
Operator
Atomic Energy Research Establishment
Status
Decommissioned
First criticality
1947

Data: IAEA RRDB · updated on Sep 3, 2026

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