A failure of governmental candor: The fire at the contaminated Santa Susana Field Laboratory via The Bulletin of Atomic Scientists

By Daniel Hirsch, February 21, 2019

The Woolsey Fire began on November 8 at the Santa Susana Field Laboratory (SSFL), located adjacent to Simi Valley, California, and enveloped much of the lab’s grounds, eventually burning all the way to Malibu and the Pacific Ocean, impacting nearly 100,000 acres. Because of widespread radioactive and toxic chemical contamination at the Santa Susana site from several nuclear reactor accidents, including a partial meltdown, and tens of thousands of rocket engine tests, the public had reason to be concerned that smoke from the fire carried contamination offsite.

In the wake of the fire, the California Department of Toxic Substances Control (DTSC) and the US Energy Department—both of which have been involved in long delays to the promised cleanup of the Santa Susana site—issued assurances that no radioactive or toxic chemical contamination had been released. At that time, however, the agencies refused to release any actual data or scientific explanation of how hundreds of acres of contaminated vegetation, growing in contaminated soil, could burn without releasing contaminants.[…]

Over the years, 10 reactors operated at Santa Susana, as well as plutonium and uranium fuel fabrication facilities and a “hot lab” where highly irradiated fuel from around the US nuclear complex was shipped for decladding and examination. Tens of thousands of rocket engine tests were also conducted at the site.

During the lab’s life, numerous reactor accidents occurred, the most famous of which was the 1959 partial meltdown of the Sodium Reactor Experiment. After a power excursion—that is, an undesired and rapid increase in power level—in the reactor core, operators were barely able to shut it down. Although they could not identify the cause of the problem, the reactor was inexplicably started up again and ran for 10 more days, in the face of rising radiation levels and clear indications of fuel damage. When the reactor was finally shut down, a third of the fuel elements were found to have experienced melting.

Like all the reactors at the Santa Susana site, the Sodium Reactor Experiment had no containment structure. During and after the accident, radioactive gases were pumped from the reactor into the atmosphere. Even so, leakage into the reactor room was so severe that the building’s loading doors were opened to vent the contamination outside, according to John Pace, one of the workers at the time. […]

As was the case throughout the nuclear complex and at many Defense Department sites, Santa Susana environmental practices were extremely poor. Radioactive and chemical wastes were routinely burned in open-air pits; often, barrels of waste were ignited by rifle fire, plumes of toxic smoke then traveling far beyond the site.


A million gallons of trichlorethylene, a carcinogenic solvent, was used to flush rocket engines after tests and allowed then to percolate into the ground and groundwater. A witches’ brew of dozens of other toxic chemicals, including polychlorinated biphenyls (PCBs), dioxins, heavy metals, volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons, and perchlorate has contaminated soil, groundwater, and surface water. A $40 million, multi-year radiation survey by the Environmental Protection Agency found hundreds of Santa Susana locations contaminated with radionuclides, including strontium 90, cesium 137, and plutonium 239.

Because the Santa Susana lab property is located in the hills overlooking populated areas, decades of stormwater runoff and wind have carried contamination offsite. A study led by UCLA’s Professor Yoram Cohen and funded by the Agency for Toxic Substances and Disease Registry found contaminants had migrated to offsite populated areas at levels in excess of EPA levels of concern. A second study, funded by the same agency and led by University of Michigan epidemiologist Hal Morgenstern, found a greater than 60 percent increase in the incidence of certain cancers in the offsite population living within two miles of the Santa Susana lab, as compared with people living five miles away. An earlier study by the UCLA School of Public Health found significant elevated death rates for key cancers among the workers, associated with their radiation and toxic chemical exposures.


Measurements from the network of air monitors set up at Santa Susana are almost entirely missing from the report. Minimal air monitor data from the time of the fire are included only on the very last page of the 267-page report (most of which is filler). There are at least 16 air monitors in the network. For some reason, the report gives data for only two of them, and only partial data at that. Where are the missing air-monitoring data from the time of the fire and why haven’t they been reported? The measurements were initially promised to be released within days of the fire, but months later, still have not. (Weeks after the release of the DTSC report, Boeing provided some minimal radiation data from two of its six air monitors. No chemical data were provided, and no data at all for the other four monitors.)

Because of widespread public distrust of state and federal agencies and the other parties responsible for the pollution at the Santa Susana, a community-initiated study is now underway.  Soil and ash samples are being collected from homes to be sent for analysis; results are some months away. It must be recognized that these measurements, taken long after the fire, will have significant limitations as well. […]

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