Santa Susana


À 40 km du centre de Los Angeles est créé le laboratoire de Santa Susana. On y teste des moteurs de fusée et des réacteurs nucléaires. De nombreux accidents s’y produisent, dont la fusion partielle d’un réacteur à sodium.

The Santa Susana Field Laboratory was established in the 1940s as a remote facility for rocket engine and nuclear reactor testing that was considered too dangerous to conduct in populated areas. It is situated in the hills overlooking Simi Valley and the west San Fernando Valley, about 25 miles from downtown Los Angeles. Since the lab was established, the population in the Los Angeles area mushroomed, and now about 500,000 people live within 10 miles of the site.

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.

Image : The Santa Susana Field Laboratory site, shown in a 2000 photo, is one of the most challenging cleanup jobs in the state, possibly the country. (Boeing )

Le réacteur expérimental au sodium a subi une fusion partielle du cœur au Santa Susana Field Laboratory près de Simi Valley, en Californie. Selon Makhijani, Président de l’Institute for Energy and Environmental Research, « les mesures d’iode-131 ont été environ 80 à 100 fois plus importantes que les relevés provenant de Three Mile Island. »