Editing SL-1 (section)

{{Short description|Nuclear reactor that killed 3 in 1961}}
{{About|the SL-1 Nuclear Reactor|the Nortel Meridian SL1 PBX|Nortel Meridian|the Sputnik rocket|Sputnik (rocket)}}
{{Infobox event
| title = SL-1 Nuclear Accident
| image_name = US AEC SL-1.JPG
| image_size = 240px
| caption = 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&nbsp;60-ton [[Manitowoc Cranes|Manitowoc]] Model 3900 crane had a {{convert|5.25|in|cm|adj=on}} steel shield with a {{convert|9|in|cm|adj=on}} thick lead glass window to protect the operator.
| date = January 3, 1961
| place = [[Idaho National Laboratory|National Reactor Testing&nbsp;Station]],<br>west of [[Idaho Falls, Idaho]], U.S.
| outcome = [[International Nuclear Event Scale|INES]] Level 4 (accident with&nbsp;local&nbsp;consequences)
| coordinates = {{Coord|43.5182|-112.8237|region:US_type:landmark|display=title,inline}}
| reported deaths = 3
| location = 
| notes = {{stack begin}}
{{Location map| USA#Idaho
| relief = 1
| label = SL-1
| lat = 43.5182
| long = -112.8237
| caption = Location in the [[United States]]##Location in [[Idaho]]
| float = 
| background = 
| border = infobox
| width = 240
}}
{{stack end}}
}}

'''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|western]] [[United States]] at the [[Idaho National Laboratory#History|National Reactor Testing Station]] (NRTS) in [[Idaho]] about {{convert|40|mi|round=5|spell=in}} west of [[Idaho Falls, Idaho|Idaho&nbsp;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 shut down 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 as well. The reactor vessel then fell down to its original position.<ref>{{Cite web |title=Proving the Principle |url=https://inl.gov/document/proving-the-principle/ |access-date=2023-12-17 |website=Idaho National Laboratory |page=142 |language=en-US}}</ref>

Initial press reports indicated that a chemical explosion was the likely cause of the accident that killed all three of its young military operators.<ref name=sdcapj4>{{cite news |url=https://news.google.com/newspapers?id=EaASAAAAIBAJ&pg=4433%2C513325 |work=Spokane Daily Chronicle |location=(Washington) |agency=Associated Press |title=3 die in reactor blast |date=January 4, 1961 |page=1}}</ref><ref name=3kdin>{{cite news |url=https://news.google.com/newspapers?id=uHkvAAAAIBAJ&pg=6455%2C479786 |work=Deseret News |location=(Salt Lake City, Utah) |last=Hale |first=Steve |title=3 killed in severe blast at Idaho A-reactor site |date=January 4, 1961 |page=A1}}</ref><ref name=lmtj5>{{cite news |url=https://news.google.com/newspapers?id=zntfAAAAIBAJ&pg=3951%2C484527 |work=Lewiston Morning Tribune |location=(Idaho) |agency=Associated Press |title=Reactor blast kills three, pours out radiation |date=January 5, 1961 |page=1}}</ref><ref name=srapj5>{{cite news |url=https://news.google.com/newspapers?id=zTJWAAAAIBAJ&pg=5509%2C1196197 |work=Spokesman-Review |location=(Spokane, Washington) |agency=Associated Press |title=3 technicians die in reactor blast |date=January 5, 1961 |page=2}}</ref> 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.<ref name=lodged>{{cite news |url=https://books.google.com/books?id=zKAvAAAAIBAJ&dq=aec%20crews%20recover%20last%20blast%20victim&pg=PA1 |work= Independent |location=(St. Petersburg, Florida) |agency=Associated Press |title=AEC crews recover last blast victim |date=January 9, 1961 |page=1}}</ref><ref name=wild>{{cite news |url=https://books.google.com/books?id=zKAvAAAAIBAJ&dq=aec%20crews%20recover%20last%20blast%20victim&pg=PA1 |work= Pittsburgh Press |location=(Pittsburgh, PA) |agency=Associated Press |title=Tame atom runs wild (part 2), Radiation poisons air, routs rescuers: suspenseful hour-by-hour story told of Idaho tragedy |date=January 9, 1961 |page=12}}</ref> It remains the only U.S. reactor accident to cause immediate deaths.<ref name=ProvePrinciple16>{{cite book| last= Stacy| first= Susan M.| title= Proving the Principle: A History of The Idaho National Engineering and Environmental Laboratory, 1949–1999| publisher= [[U.S. Department of Energy]], Idaho Operations Office| date= 2000| pages= 150–57| chapter= Chapter 16: The Aftermath| chapter-url= http://www4vip.inl.gov/publications/d/proving-the-principle/chapter_15.pdf| isbn= 0-16-059185-6| access-date= 2015-09-08| archive-date= 2016-12-29| archive-url= https://web.archive.org/web/20161229141617/http://www4vip.inl.gov/publications/d/proving-the-principle/chapter_15.pdf| url-status= dead}}</ref>

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 [[Distant Early Warning Line|DEW Line]].<ref>{{cite news |title=Idaho: Runaway Reactor|url=http://www.time.com/time/magazine/article/0,9171,828698,00.html|archive-url=https://web.archive.org/web/20100211195036/http://www.time.com/time/magazine/article/0,9171,828698,00.html|url-status=dead|archive-date=February 11, 2010|access-date=July 30, 2010|newspaper=[[Time (magazine)|Time]]|date=January 13, 1961}}</ref> The design power was 3&nbsp;[[megawatt|MW]] ([[Thermal energy|thermal]]),<ref name="design" /> but some 4.7&nbsp;MW tests had been performed in the months before the accident. Useful power output was 200&nbsp;[[kilowatt|kW]] [[Electrical energy|electrical]] and 400&nbsp;kW for space heating.<ref name=design/>

During the accident, the core power level reached nearly 20&nbsp;[[gigawatt|GW]] within four milliseconds, causing the explosion.<ref>{{cite journal |journal= System Failure Case Studies |url= http://pbma.nasa.gov/docs/public/pbma/general/sl1_sfcs.pdf |publisher= NASA |title= Supercritical |editor= Steve Wander  |volume= 1 |issue= 4 |date= February 2007 |access-date= 2007-10-05 |url-status= dead |archive-url= https://web.archive.org/web/20071127025626/http://pbma.nasa.gov/docs/public/pbma/general/sl1_sfcs.pdf |archive-date= 2007-11-27}}</ref><ref name=tucker/><ref>[https://fas.org/sgp/othergov/doe/lanl/la-3611.pdf LA-3611 ''A Review of Criticality Accidents''], William R. Stratton, [[Los Alamos Scientific Laboratory]], 1967</ref><ref name=la13638>[http://www.orau.org/ptp/library/accidents/la-13638.pdf LA-13638 ''A Review of Criticality Accidents'' (2000 Revision)], Thomas P. McLaughlin, et al., [[Los Alamos National Laboratory]], 2000.</ref> The direct cause was the over-withdrawal of the central control rod, a reactor component designed to absorb [[neutron]]s in the reactor's core.

The accident released about {{convert|80|Ci|TBq|lk=on}} of [[iodine-131]].<ref name=IEER>[http://www.ieer.org/reports/accident.html The Nuclear Power Deception] Table 7: Some Reactor Accidents</ref> This was not considered significant, due to its location in the remote high desert of [[Eastern Idaho]]. About {{convert|1100|Ci|TBq}} of [[fission products]] were released into the atmosphere,<ref name=Exposure>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.</ref> including the [[isotopes of xenon]], [[isotopes of krypton]], [[strontium-91]], and [[yttrium-91]] detected in the tiny town of [[Atomic City, Idaho]].<ref name=Joint61 />

A memorial plaque for the three men was erected in 2022 at the [[Experimental Breeder Reactor]] site.<ref name=plaque>[https://www.atomictourism.us/2022/06/20/sl-1-memorial-plaque/ SL-1 Memorial Plaque]</ref>