On July 26, 1959, an experimental nuclear reactor in the Simi Hills just to the west of Canoga Park and Chatsworth suffered a partial meltdown of its core. Ten of 43 fuel assemblies were damaged, and in the rush to contain the emergency a considerable amount of radioactive gas was released into the air.
Scientists, residents and anti-nuclear activists still debate what if any health effects resulted. The story of the nation’s first civilian reactor, and its partial meltdown, is a little-known part of local history.
In brief, rocket testing began at the Santa Susana Field Laboratory in Woolsey Canyon, reached off Valley Circle Drive west of Chatsworth Reservoir, in 1947. Engines for the first U.S. space rockets were test fired there by Rocketdyne, and anyone who lived in the West Valley in the 1950s and ’60s knew the audible roar and red glow in the sky on test nights.
In 1956, Atomics International — a sister firm to Rocketdyne — began to secretly develop a nuclear reactor on the site. It was a test reactor, to be cooled not with water but with sodium. Southern California Edison backed the research. On July 12, 1957 the first commercial nuclear power generated anywhere in the U.S. began to flow from Santa Susana.
Later that year, the CBS News program “See It Now” with Edward R. Murrow reported on the achievement, which provided all of the power for the Ventura County city of Moorpark.
Then came the July 1959 accident, which was not disclosed for more than a month. The reactor continued operating until 1964. Concerns about the legacy of contamination at Santa Susana — and allegations of higher than expected cancer rates among nearby residents — have kept it the subject of ongoing investigation.