SL-1

This article is about the SL-1 Nuclear Reactor. For the Nortel Meridian SL1 PBX, see Nortel Meridian. For the Sputnik rocket, see Sputnik (rocket).
SL-1 Nuclear Meltdown
November 29, 1961: The reactor vessel being removed from the reactor building, which acted substantially like the containment building used in modern nuclear facilities. The 60-ton Manitowoc Model 3900 crane had a 5.25-inch (13.3 cm) steel shield with a 9-inch (23 cm) thick lead glass window to protect the operator.
DateJanuary 3 1961
LocationNational Reactor Testing Station,
west of Idaho Falls, Idaho, U.S.
Coordinates43°31′06″N 112°49′25″W / 43.5182°N 112.8237°W / 43.5182; -112.8237
OutcomeINES Level 4 (accident with local consequences)
Deaths3
SL-1 is located in the United States
SL-1
SL-1
Location in the United States
SL-1 is located in Idaho
SL-1
SL-1
Location in Idaho

Stationary Low-Power Reactor Number One, also known as SL-1, initially the Argonne Low Power Reactor (ALPR), was a United States Army experimental nuclear reactor in the western United States at the National Reactor Testing Station (NRTS) in Idaho about forty miles (65 km) west of Idaho Falls, now the Idaho National Laboratory. On January 3, 1961, at 9:01 pm MST, an operator fully pulled out the reactor's central control rod, causing the reactor to go from fully shutdown to prompt critical. The intense heat from the nuclear reaction expanded the water inside the reactor core, producing extreme water hammer and causing water, steam, reactor components, debris, and fuel to vent from the top of the reactor where the three operators were working. As the water struck the top of the reactor vessel, it propelled the entire reactor vessel to the ceiling of the reactor room where it struck the overhead crane. A supervisor who had been on top of the reactor lid was impaled by an expelled control rod shield plug and pinned to the ceiling. The release of materials hit the two other operators, mortally injuring them. The reactor vessel then fell down to its original position.[1]

Initial press reports indicated that a chemical explosion was the likely cause of the accident that killed all three of its young military operators.[2][3][4][5] By January 9, 1961, the press began reporting that an operator had been "lodged in the upper structure of the reactor building" prior to the body's removal at 2:37 am on January 9.[6][7] It remains the only U.S. reactor accident to cause immediate deaths.[8]

Part of the Army Nuclear Power Program, SL-1 was a prototype for reactors 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.[9] The design power was 3 MW (thermal),[10] but some 4.7 MW tests were performed in the months before the accident. Useful power output was 200 kW electrical and 400 kW for space heating.[10]

During the accident, the core power level reached nearly 20 GW in just four milliseconds, causing the explosion.[11][12][13][14] The direct cause was the over-withdrawal of the central control rod that absorbed neutrons in the reactor's core. The accident released about 80 curies (3.0 TBq) of iodine-131,[15] 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.[16]

  1. ^ "Proving the Principle". Idaho National Laboratory. p. 142. Retrieved 2023-12-17.
  2. ^ "3 die in reactor blast". Spokane Daily Chronicle. (Washington). Associated Press. January 4, 1961. p. 1.
  3. ^ Hale, Steve (January 4, 1961). "3 killed in severe blast at Idaho A-reactor site". Deseret News. (Salt Lake City, Utah). p. A1.
  4. ^ "Reactor blast kills three, pours out radiation". Lewiston Morning Tribune. (Idaho). Associated Press. January 5, 1961. p. 1.
  5. ^ "3 technicians die in reactor blast". Spokesman-Review. (Spokane, Washington). Associated Press. January 5, 1961. p. 2.
  6. ^ "AEC crews recover last blast victim". Independent. (St. Petersburg, Florida). Associated Press. January 9, 1961. p. 1.
  7. ^ "Tame atom runs wild (part 2), Radiation poisons air, routs rescuers: suspenseful hour-by-hour story told of Idaho tragedy". Pittsburgh Press. (Pittsburgh, PA). Associated Press. January 9, 1961. p. 12.
  8. ^ Stacy, Susan M. (2000). "Chapter 16: The Aftermath" (PDF). Proving the Principle: A History of The Idaho National Engineering and Environmental Laboratory, 1949–1999. U.S. Department of Energy, Idaho Operations Office. pp. 150–57. ISBN 0-16-059185-6. Archived from the original (PDF) on 2016-12-29. Retrieved 2015-09-08.
  9. ^ "Idaho: Runaway Reactor". Time. January 13, 1961. Archived from the original on February 11, 2010. Retrieved July 30, 2010.
  10. ^ a b Cite error: The named reference design was invoked but never defined (see the help page).
  11. ^ Steve Wander, ed. (February 2007). "Supercritical" (PDF). System Failure Case Studies. 1 (4). NASA. Archived from the original (PDF) on 2007-11-27. Retrieved 2007-10-05.
  12. ^ Cite error: The named reference tucker was invoked but never defined (see the help page).
  13. ^ LA-3611 A Review of Criticality Accidents, William R. Stratton, Los Alamos Scientific Laboratory, 1967
  14. ^ LA-13638 A Review of Criticality Accidents (2000 Revision), Thomas P. McLaughlin, et al., Los Alamos National Laboratory, 2000.
  15. ^ The Nuclear Power Deception Table 7: Some Reactor Accidents
  16. ^ Horan, J. R., and J. B. Braun, 1993, Occupational Radiation Exposure History of Idaho Field Office Operations at the INEL, EGG-CS-11143, EG&G Idaho, Inc., October, Idaho Falls, Idaho.