Woolsey Fire and the Santa Susana Field Laboratory

Above: Aerial photo from CBSLA showing the start of the fire at SSFL. https://twitter.com/Stu_Mundel/status/1060692904107110400

We’ve received quite a few inquiries over the past several days regarding the potential consequences of the Woolsey Fire in Southern California, which has burned through part of the Santa Susana Field Laboratory (SSFL) site in Ventura County immediately south of Simi Valley. The SSFL site, which closed in 1996, housed ten nuclear reactors as well as rocket engine test facilities, and is highly contaminated with radioactive and toxic wastes remaining from decades of poor disposal practices and numerous accidents. The public is understandably concerned about the possibility that contaminants have been spread by the fire, which reached the site on Fri. Nov. 8th, but was reportedly no longer burning within it the following day.

SAFECAST radiation map of the region affected by the Woolsey fire, with CAL FIRE data overlay. SSFL location indicated by a red dot.

Safecast had no survey data from the immediate SSFL area prior to the fire, but we had a fair amount of data from nearby communities which showed it to be at normal background levels. Our realtime radiation and particulate sensors in the Southern California region, the closet of which is 30km (about 18 miles) away from SSFL, have shown no measurable increases in radiation. Safecast volunteers are on the way to the site, however, so hopefully we will have new data to share soon. Though CalFire indicates that the fire danger in the SSFL area has passed, many roads are still closed, making access difficult.

Sattelite imagery from JPL/ARIA. Areas affected by the Woolsey fire are shown in color. SSFL is located within the area indicated by the green circle (annotated by Safecast).

Official agencies, including the California Department of Toxic Substances Control (DTSC ) and the LA County Department of Public Health have issued statements saying that they have surveyed the site and detected no radiation above normal background levels. As of this writing, neither agency has provided actual measurement data or details about their methodology. One potential health concern would be from inhalation of radioactive material lofted by the fire and carried by the smoke plumes. Inhalation of smoke and particulate matter itself certainly presents a health risk, and people living in the region have been advised to protect themselves against that. As has been demonstrated at Chernobyl, wildfires in radioactively contaminated areas can resuspend radioactive material and carry it significant distances. The Chernobyl research cited above, which analysed the effects of fires of similar magnitude to Woolsey in a more highly contaminated region, suggested that radiation doses to the most affected people would be higher than background but still within the same range. These researchers were able to make these estimates because they were able to carefully measure the radiation that was released by the fires.

Aerial photo of SSFL site, 1985, showing sites of accidents and other incidents (Credits: photo: DOE; annotations: SSFL Work Group)

Radioactivity from ground contamination is relatively easy to measure, and we should be able to answer some questions about this soon. In addition, we will continue to look for available data that might show changes in airborne radiation that may have been caused by this fire. This would have to come from radiation monitors that were already in place nearby beforehand. This is why Safecast continues to stress the importance of having sensors in place before an incident like this occurs. Without adequate data, important questions cannot be answered, and there is no substitute for being prepared.


More information:

KTLA news coverage


CALFIRE evacuation map

Advanced Rapid Imaging and Analysis (ARIA) imagery from NASA’s JPL

Rocketdyne SSFL facility maps

Massive Woolsey Fire Began On Contaminated Santa Susana Field Laboratory, Close to Site of Partial Meltdown, Physicians for Social Responsibility, LA, Nov 12, 2018


Supplemental Detailed Comments Regarding the Department of Toxic Substances Control Draft Program Environmental Impact Report on Cleanup of the Santa Susana Field Laboratory by the Committee to Bridge the Gap and the Natural Resource Defense Council; 14 December 2017

Wikipedia: Santa Susana Field Laboratory

Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment, Evangeliou et al, Nature scientific Reports, volume 6, Article number: 26062 (2016)