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Sodium Reactor Experiment: Difference between revisions
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== {{anchor|Location and setting}}Location == | == {{anchor|Location and setting}}Location == | ||
The Sodium Reactor Experiment facility was situated in a northwestern administrative section (known as Area IV) on a mountaintop known as ''The Hill'' of the [[Santa Susana Field Laboratory]], about {{convert|30|mi}} northwest of downtown | The Sodium Reactor Experiment facility was situated in a northwestern administrative section (known as Area IV) on a mountaintop known as ''The Hill'' of the [[Santa Susana Field Laboratory]], about {{convert|30|mi}} northwest of downtown Los Angeles in [[Simi Valley]].<ref name=PS2009-08-24>{{cite web|url=https://psmag.com/environment/50-years-after-nuclear-meltdown-3510|title=50 Years After America's Worst Nuclear Meltdown: Human error helped worsen a nuclear meltdown just outside Los Angeles, and now human inertia has stymied the radioactive cleanup for half a century|date=August 24, 2009|work=[[Pacific Standard]]|last1=Trossman Bien|first1=Joan|last2=Collins|first2=Michael|access-date=November 14, 2018}}</ref> When the Sodium Reactor Experiment was active, the Santa Susana Field Laboratory was operated by two business divisions of the [[North American Aviation]] company. The [[Rocketdyne]] division conducted [[liquid-propellant rocket]] engine testing and development at the site, while the Atomics International division focused on the development of commercial nuclear reactors and compact nuclear reactors for [[outer space|outer-space]] applications. | ||
== History == | == History == | ||
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On July 13, the reactor experienced a series of temperature and radiation fluctuations (known as "excursions", because they were an unexpected departure from expected conditions). The power level rose from about 4 MW to about 14 MW (70% of full power) over a period of about two minutes.<ref>{{cite book | last = Ashley| first = R.L. |display-authors=etal | title = SRE Fuel Element Damage, Final Report of the Atomics International Ad Hoc Committee | year =1961 | pages = III–21 | url = http://etec.energy.gov/Library/Main/Doc._No._2_SRE_Fuel_Element_Damage_Final_Report_1961_NAA-SR-4488_%28suppl%29.pdf | id = NAA-SR-4488-supl | access-date = 14 April 2012 }}</ref> The excursion required the operators to manually override a malfunctioning automatic-control switch, and the reactor was shut down. The switch was repaired, and the reactor was slowly restarted.<ref name=Jarett /> The following day, monitors again indicated elevated airborne radioactivity levels within the reactor building. The source was traced to two locations at the reactor core loading face, which were sealed. Airborne radioactivity within the reactor building was reduced. The reactor was restarted, but the operators noted unusual behavior over the next few days. The reactor increased power faster than expected, and the temperature difference between the reactor bottom (where the sodium entered) and the reactor top (where the sodium exited) was unusually high. Radioactivity within the reactor also increased. The operators investigated, performing several exercises to understand and correct the reactor behavior. | On July 13, the reactor experienced a series of temperature and radiation fluctuations (known as "excursions", because they were an unexpected departure from expected conditions). The power level rose from about 4 MW to about 14 MW (70% of full power) over a period of about two minutes.<ref>{{cite book | last = Ashley| first = R.L. |display-authors=etal | title = SRE Fuel Element Damage, Final Report of the Atomics International Ad Hoc Committee | year =1961 | pages = III–21 | url = http://etec.energy.gov/Library/Main/Doc._No._2_SRE_Fuel_Element_Damage_Final_Report_1961_NAA-SR-4488_%28suppl%29.pdf | id = NAA-SR-4488-supl | access-date = 14 April 2012 }}</ref> The excursion required the operators to manually override a malfunctioning automatic-control switch, and the reactor was shut down. The switch was repaired, and the reactor was slowly restarted.<ref name=Jarett /> The following day, monitors again indicated elevated airborne radioactivity levels within the reactor building. The source was traced to two locations at the reactor core loading face, which were sealed. Airborne radioactivity within the reactor building was reduced. The reactor was restarted, but the operators noted unusual behavior over the next few days. The reactor increased power faster than expected, and the temperature difference between the reactor bottom (where the sodium entered) and the reactor top (where the sodium exited) was unusually high. Radioactivity within the reactor also increased. The operators investigated, performing several exercises to understand and correct the reactor behavior. | ||
On July 23, it was decided to shut the reactor down because of high fuel temperature and an unacceptable top-bottom reactor temperature differential. While moving the elements to dislodge foreign material (and lower the exit temperatures), it was noticed that four reactor elements were stuck. On July 26 the reactor was shut down, and the first damaged fuel element was observed.<ref>Sahagun, Luis, "[http://www.latimes.com/news/science/environment/la-me-meltdown13-2009jul13,0,6792951.story?track=rss Marking the 50th anniversary of the first U.S. nuclear meltdown]", '' | On July 23, it was decided to shut the reactor down because of high fuel temperature and an unacceptable top-bottom reactor temperature differential. While moving the elements to dislodge foreign material (and lower the exit temperatures), it was noticed that four reactor elements were stuck. On July 26 the reactor was shut down, and the first damaged fuel element was observed.<ref>Sahagun, Luis, "[http://www.latimes.com/news/science/environment/la-me-meltdown13-2009jul13,0,6792951.story?track=rss Marking the 50th anniversary of the first U.S. nuclear meltdown]", ''Los Angeles Times'', July 16, 2009.</ref> | ||
On July 29, 1959, an ''ad hoc'' investigative committee was established to study the incident and make recommendations. On August 21, 1959, [[Los Angeles Daily News|''The Van Nuys News'']] published a story with the headline “Parted Fuel Element seen at Atomics International”. The article stated, “…a parted fuel element was observed” and “The fuel element damage is not an indication of unsafe reactor conditions. No release of radioactive materials to the plant or its environs occurred”.<ref>{{cite web | last = U.S. Department of Energy | title = Community Meeting Presentation | date = September 9, 2004 | location = See slide 13 |url = http://etec.energy.gov/Library/Main/septpres.pdf | access-date = 22 April 2012 }}</ref> The investigative committee released “SRE Fuel Element Damage, An Interim Report” on November 15, 1959; the final report was made in 1961. The introductory material in both documents includes the statement, ”This report has been distributed according to the category ‘Reactors-Power’ as given in Standard Distribution Lists for Unclassified Scientific and Technical Reports", also noting that a total of 700 copies were printed.<ref name=Jarett /> The documents were not labeled “secret”. | On July 29, 1959, an ''ad hoc'' investigative committee was established to study the incident and make recommendations. On August 21, 1959, [[Los Angeles Daily News|''The Van Nuys News'']] published a story with the headline “Parted Fuel Element seen at Atomics International”. The article stated, “…a parted fuel element was observed” and “The fuel element damage is not an indication of unsafe reactor conditions. No release of radioactive materials to the plant or its environs occurred”.<ref>{{cite web | last = U.S. Department of Energy | title = Community Meeting Presentation | date = September 9, 2004 | location = See slide 13 |url = http://etec.energy.gov/Library/Main/septpres.pdf | access-date = 22 April 2012 }}</ref> The investigative committee released “SRE Fuel Element Damage, An Interim Report” on November 15, 1959; the final report was made in 1961. The introductory material in both documents includes the statement, ”This report has been distributed according to the category ‘Reactors-Power’ as given in Standard Distribution Lists for Unclassified Scientific and Technical Reports", also noting that a total of 700 copies were printed.<ref name=Jarett /> The documents were not labeled “secret”. | ||