Restoration of the NRX Reactor

The world's first nuclear meltdown

By Nick Touran, Ph.D., P.E., 2024-11-13 , Reading time: 7 minutes

On December 12, 1952, the NRX reactor in Ontario, Canada suffered an accidental runaway. The increased power caused the fuel to heat up such that some of it melted, thereby becoming the first ever nuclear meltdown in history. Highly radioactive material spilled into the basement, and around 1 million gallons of water containing 10,000 Ci of fission products had to be disposed of. The NRX was restored and turned back on with improved safety systems and uprated power. It operated until 1993.

I recently found this film summarizing the accident and cleanups. I got it scanned, and have posted it online here.

(If you’ve heard of the reactor accident that Jimmy Carter helped with while he was in the Navy, this is it. Does anyone see young Jimmy Carter in the footage?)

Catalog description: This film discusses the 14-month repair and restoration of the NRX Reactor at Chalk River, Ontario, following a rapid super operational power level excursion (the first nuclear reactor runaway in history) and describes the 1959 safety system of the 40-Mw reactor. Film footage made during actual restoration is supplemented by studio explanation with a reactor model. Depicted are the unusual and hazardous problems complicating repairs: high levels of radioactive contamination in work areas; continuation of water cooling on high irradiated fuel rods to prevent auto-ignition; creation of disposal facilities in subzero weather for a gross quantity of cooling water mixed with highly active fission products; corrosion-inhibiting preservation of irradiated fuel rods; decontamination of large pieces of equipment and reactor components; and rebuilding a reactor that had not been designed initially for major repair. Illustrated are unique methods and tools for locating radioactive products lodged in piping and auxiliary equipment, snaring and removing broken pieces of radioactive fuel rods, suppressing large areas of residual building contamination, and removing and decontaminating equipment, shielding, and heavy water. In addition to persons interested in nuclear reactors, the film has particular value to reactor technology and operation for assessing safety system failure and associated problems and hazards of returning a reactor to operation.

This is film 88248 in our catalog.

This digitization was sponsored by me.

Restoration of the NRX Reactor

The world's first nuclear meltdown

Additional NRX Links

See Also