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The Santa Susana Field Laboratory’s Area IV’s extensive radiological contamination is the result of partial meltdowns, accidents, spills along with burning and dumping. Six out of ten experimental reactors suffered major accidents including the 1959 partial meltdown of the Sodium Reactor Experiment, or SRE, which released hundreds of times more of certain types of radionuclides into the environment as did the infamous Three Mile Island meltdown did in Pennsylvania in 1979.

The lasting effects of radiological and chemical contamination at Area IV, and the surrounding communities, are still present today and this section of SSFL is undergoing a characterization and cleanup that will cost hundreds of millions and take until at least 2017. In the process of the fight over Rocketdyne, which began in the late 1980s with revelations of the true extent of the SRE meltdown, workers and residents have died allegedly because of Rocketdyne pollution, and huge fines have been assessed the company that now owns the site, Boeing. Our investigation of this site, begun in early 1998, has documented much of the history of this site which can be accessed at our Rocketdyne Investigation page.

The Department of Energy, or DOE, which is responsible for the cleanup of 90-acre Energy Technology Engineering Center (ETEC) in Area IV, has created a website that is linked to throughout’s extensive Area IV galleries. DOE estimates that the final cost of remediating ETEC will cost between $167.9 million to $221.4 million.

  • Ahmanson Ranch Dedication
SSFL Area IV - Maps

SSFL Area IV geographic groupings, DOE ETEC clean-up map, Area IV building locations, and more.


The Santa Susana Field Laboratory's 270-acre Area IV is dominated by the 90-acre Energy Technology Engineering Center where Rocketdyne's nuclear work was performed.


Empire State Atomic Development Authority tested piping burst characteristics under sodium water reaction conditions. Burro Flats Fault may transport sodium down into Runkle Canyon which tests high for it.

SSFL Area IV - Sodium Burn Pit

"The [Former Sodium Disposal Facility], otherwise known as the “FSDR” or “Sodium Burn Pit”, was used to toss highly radioactive barrels of sodium into. Then a rifle shot set the barrels ablaze in an incredibly dangerous way.

SSFL Area IV - KEWB Reactor

Kinetics Experiment Water Boiler (KEWB) reactor was first nuclear reactor at SSFL. Used water solution of uranyl sulfate as nuclear fuel. Two different cores were used. Last operations 1966. January 1975 demolition begins.


SNAP-10A was only nuclear reactor launched and flight tested by U.S.. Reactor was developed under Systems Nuclear Auxiliary Power Program (SNAP) program.

SSFL Area IV Reactor Lifecycle

2004 U.S. Department of Energy presentation called "DOE Radiological Activities in Area IV."

SSFL Area IV - Gallery A - Buildings 4003, 4005, 4009, 4011 & 4023

From 1957 through 1964, Building 4003 was used to assemble fuel for the Sodium Reactor Experiment. SRE partially melted down in 1959.

SSFL Area IV - Gallery B - Building 4020 - Hot Lab

SSFL Area IV Building 4020, the Hot Lab, where plutonium fuel rods from around the country were cut apart. Extremely radioactive.

SSFL Area IV - Gallery C - Building 4022 - Radioactive Materials Handling Facility

“The RMHF was constructed in 1959 and consists of a group of ten buildings which were built to safely handle new and irradiated nuclear fuel,” says DOE.

SSFL Area IV - Gallery D - Building 4028 - Shield Test Irradiation Reactor

"[C]onstructed in 1960 to perform tests on space reactor shields,” according to DOE. “The original reactor was the Shield Test Reactor, a 50 kW reactor that operated in a pool of water from 1961 to 1964."

SSFL Area IV - Gallery E - Buildings 4029, 4030, 4055, 4064, 4093 & 4100

SSFL Area IV Building 4029 was Radiation Measurements Facility where in March 1964 a radium source was dropped in storage thimble causing contamination detected in 1987.

SSFL Area IV - Sodium Reactor Experiment

7 GALLERIES depict the life cycle of the Sodium Reactor Experiment, or SRE, first nuclear reactor to supply commercially-available electricity. Reactor suffered worst American meltdown in 1959.

SSFL Area IV 11-08-08

Open gate without signs leads into Area IV in heights above Runkle Canyon. "ENTS," or Engineered Natural Treatment Systems, are seen here as well as lab's nuclear area. Eleven acres of Area IV drain into Runkle Canyon.

25 Years of Award-Winning SSFL/Rocketdyne Reporting