United States · Los Alamos, NM · 35.893, -106.300 (approximate location)

Topsy

Topsy, a research reactor (critical assembly) in Los Alamos, NM, United States, with 600 W of thermal power, operated by Los Alamos Scientific Laboratory. Decommissioned, first critical in 1948.

It was one of the 340 research reactors the United States has had; 48 remain in operation today. It went critical 6 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

Los Alamos, NM

Type

Critical assembly

Thermal power

600 W

Operator

Los Alamos Scientific Laboratory

Status

Decommissioned

First criticality

1948

See also: every research reactor in United States · How research reactors work