Nuclear Reactor Meltdown: "SL-1 Accident Briefing Film Report" 1961 Atomic Energy Commission

more at http://quickfound.net/

Originally a public domain film, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/SL-1

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

The SL-1, or Stationary Low-Power Reactor Number One, was a United States Army experimental nuclear power reactor in the United States that underwent a steam explosion and meltdown on January 3, 1961, killing its three operators. The direct cause was the improper withdrawal of the central control rod, responsible for absorbing neutrons in the reactor core. The event is the only reactor accident in the U.S. that resulted in immediate fatalities. The accident released about 80 curies (3.0 TBq) of iodine-131, which was not considered significant due to its location in the remote high desert of eastern Idaho. About 1,100 curies (41 TBq) of fission products were released into the atmosphere.

The facility, located at the National Reactor Testing Station (NRTS) approximately forty miles (65 km) west of Idaho Falls, Idaho, was part of the Army Nuclear Power Program and was known as the Argonne Low Power Reactor (ALPR) during its design and build phase. It was intended to provide electrical power and heat for small, remote military facilities, such as radar sites near the Arctic Circle, and those in the DEW Line. The design power was 3 MW (thermal), but some 4.7 MW tests were performed in the months prior to the accident. Operating power was 200 kW electrical and 400 kW thermal for space heating.

During the accident the core power level reached nearly 20 GW in just four milliseconds, precipitating the steam explosion...

On December 21, 1960, the reactor was shut down for maintenance, calibration of the instruments, installation of auxiliary instruments, and installation of 44 flux wires to monitor the neutron flux levels in the reactor core. The wires were made of aluminum, and contained slugs of aluminum–cobalt alloy.

On January 3, 1961, the reactor was being prepared for restart after a shutdown of eleven days over the holidays. Maintenance procedures required that the main central control rod be manually withdrawn a few inches to reconnect it to its drive mechanism. At 9:01 p.m., this rod was suddenly withdrawn too far, causing SL-1 to go prompt critical instantly. In four milliseconds, the heat generated by the resulting enormous power excursion caused fuel inside the core to melt and to explosively vaporize. The expanding fuel produced an extreme pressure wave that blasted water upward, striking the top of the reactor vessel with 460,000 foot-pounds (620,000 J). The slug of water was propelled at about 159 feet per second (48 m/s) with average pressure of around 500 pounds per square inch (3,400 kPa). This extreme form of water hammer propelled the entire reactor vessel upward at about 27 feet per second (8.2 m/s), while the shield plugs were ejected at about 85 feet per second (26 m/s). With 6 holes on the top of the reactor vessel, high pressure water and steam sprayed the entire room with radioactive debris from the damaged core... The entire time for the excursion, steam explosion, and vessel movement took between two and four seconds.

The spray of water and steam knocked two operators onto the floor, killing one and severely injuring another... the results of the autopsy... suggested that Byrnes and Legg died instantly, while McKinley showed signs of diffuse bleeding within his scalp, indicating he survived approximately two hours before succumbing to his wounds. All three men succumbed to injuries from physical trauma; however, the radiation from the nuclear excursion would have given the men no chance of survival even if they had not been killed by the explosion stemming from the criticality accident.