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United States United States · Simi Valley, CA · 34.270, -118.746 (approximate location)

OMR Organic Moderated Reactor

OMR Organic Moderated Reactor, a research reactor (critical assembly) in Simi Valley, CA, United States, with 1 W of thermal power, operated by Rockwell International. Decommissioned, first critical in 1958.

It was one of the 340 research reactors the United States has had; 48 remain in operation today. It went critical 16 years after the first research reactor in the United States, CP-1, Chicago Pile 1 (1942). 44 critical assemblies remain in operation today across 12 countries.

Country
United States
City
Simi Valley, CA
Type
Critical assembly
Thermal power
1 W
Operator
Rockwell International
Status
Decommissioned
First criticality
1958

Data: IAEA RRDB · updated on Sep 3, 2026

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