sharon sanders
Editor-in-Chief & President
Level 7: Major accident
<dl><dt>Impact on people and environment</dt><dd>Major release of radio*active *material with widespread health and environmental effects r*equiring implementation of planned and extended *countermeasures</dd></dl> <dl><dd>There has been only one such incident to date:
<dl><dt>Impact on people and environment</dt><dd>Significant release of radioactive material likely to require implementation of planned countermeasures.</dd></dl> <dl><dd>There has been only one such incident to date:
<dl><dt>Impact on people and environment</dt><dd>Limited release of radioactive *material likely to require i*mplementation of some planned* countermeasures.</dd><dd>Several deaths from *radiation.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Severe damage to reactor core.</dd><dd>Release of large quantities of radioactive material within an installation with a high probability of significant public exposure. This could arise from a major criticality accident or fire.</dd></dl> <dl><dd>Examples:
<dl><dt>Impact on people and environment</dt><dd>Minor release of radioactive material unlikely to result in implementation of planned countermeasures other than local food controls.</dd><dd>At least one death from radiation.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Fuel melt or damage to fuel *resulting in more than 0.1% release of core inventory.</dd><dd>Release of significant quantities of radioactive material within an installation with a high *probability of significant public exposure.</dd></dl> <dl><dd>Examples:
<dl><dt>Impact on people and environment</dt><dd>Exposure in excess of ten times the statutory annual limit for workers.</dd><dd>Non-lethal deterministic health effect (e.g., burns) from radiation.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Exposure rates of more than 1 Sv/h in an operating area.</dd><dd>Severe contamination in an area not expected by design, with a low probability of *significant public exposure.</dd></dl> <dl><dt>Impact on defence-in-depth</dt><dd>Near accident at a nuclear power plant with no safety provisions remaining.</dd><dd>Lost or stolen highly radioactive sealed source.</dd><dd>Misdelivered highly radioactive sealed source without adequate procedures in place to handle it.</dd></dl> <dl><dd>Examples:
<dl><dt>Impact on people and environment</dt><dd>Exposure of a member of the public in excess of 10 mSv.</dd><dd>Exposure of a worker in excess of the statutory annual limits.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Radiation levels in an operating area of more than 50 mSv/h.</dd><dd>Significant contamination within the facility into an area not expected by design.</dd></dl> <dl><dt>Impact on defence-in-depth</dt><dd>Significant failures in safety *provisions but with no actual *consequences.</dd><dd>Found highly radioactive sealed orphan source, device or transport package with safety provisions intact.</dd><dd>Inadequate packaging of a highly radioactive sealed source.</dd></dl> <dl><dd>Examples:
<dl><dt>Impact on defence-in-depth</dt><dd>Overexposure of a member of the public in excess of statutory *annual limits.</dd><dd>Minor problems with safety components with significant defence-in-depth remaining.</dd><dd>Low activity lost or stolen radioactive source, device or transport package.</dd></dl> (Arrangements for reporting minor events to the public differ from country to country. It is difficult to ensure precise consistency in rating events between INES Level-1 and Below scale/Level-0)
<dl><dd>Examples:
No safety significance.
<dl><dd>Examples:
http://en.wikipedia.org/wiki/International_Nuclear_Event_Scale
<dl><dt>Impact on people and environment</dt><dd>Major release of radio*active *material with widespread health and environmental effects r*equiring implementation of planned and extended *countermeasures</dd></dl> <dl><dd>There has been only one such incident to date:
- Chernobyl disaster, 26 April 1986. A power surge during a test procedure resulted in a criticality accident, leading to a powerful steam explosion and fire that released a significant fraction of core material into the environment, resulting in a death toll of 56 as well as estimated 4,000 additional cancer fatalities among people exposed to elevated doses of radiation. As a result, the city of Chernobyl (pop. 14,000) was largely abandoned, the larger city of Pripyat (pop. 49,400) was completely abandoned, and a 30km exclusion zone was established. The Chernobyl disaster is the only Level 7 Event that has occurred to date.
<dl><dt>Impact on people and environment</dt><dd>Significant release of radioactive material likely to require implementation of planned countermeasures.</dd></dl> <dl><dd>There has been only one such incident to date:
- Kyshtym disaster at Mayak, Soviet Union, 29 September 1957. A failed cooling system at a military nuclear waste reprocessing facility caused a steam explosion that released 70?80 tons of highly radioactive material into the environment. Impact on local population is not fully known. This is the only accident to go over 5 on scale besides Chernobyl. <sup id="cite_ref-1" class="reference">[2]</sup>
<dl><dt>Impact on people and environment</dt><dd>Limited release of radioactive *material likely to require i*mplementation of some planned* countermeasures.</dd><dd>Several deaths from *radiation.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Severe damage to reactor core.</dd><dd>Release of large quantities of radioactive material within an installation with a high probability of significant public exposure. This could arise from a major criticality accident or fire.</dd></dl> <dl><dd>Examples:
- Windscale fire (United Kingdom), 10 October 1957. Annealing of graphite moderator at a military air-cooled reactor caused the graphite and the metallic uranium fuel to catch fire, releasing radioactive pile material as dust into the environment.
- Three Mile Island accident near Harrisburg, PA (United States), 28 March 1979. <sup id="cite_ref-2" class="reference">[3]</sup> A combination of design and operator errors caused a gradual loss of coolant, leading to a partial meltdown. Radioactive gases were released into the atmosphere.
- First Chalk River Accident,<sup class="Template-Fact" title="This claim needs references to reliable sources from March 2011" style="white-space: nowrap;">[citation needed]</sup> Chalk River, Ontario (Canada), 12 December 1952. Reactor core damaged.
- Goi?nia accident (Brazil), 13 September 1987. An unsecured caesium chloride radiation source left in an abandoned hospital was recovered by scavenger thieves unaware of its nature and sold at a scrapyard. 249 people were contaminated and 4 died.
- As of 18 March 2011 (2011 -03-18)<sup class="plainlinks noprint asof-tag update" style="display: none;">[update]</sup>, Fukushima I nuclear accidents (reactors 1, 2 and 3) (Note: each reactor in this event was rated seperatly this event is not rated as a whole.) (Japan), events following the 2011 Tōhoku earthquake and tsunami.<sup id="cite_ref-3" class="reference">[4]</sup> The nuclear authorities of France, Finland and the USA have unofficially rated them as level 6.<sup id="cite_ref-4" class="reference">[5]</sup>
<dl><dt>Impact on people and environment</dt><dd>Minor release of radioactive material unlikely to result in implementation of planned countermeasures other than local food controls.</dd><dd>At least one death from radiation.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Fuel melt or damage to fuel *resulting in more than 0.1% release of core inventory.</dd><dd>Release of significant quantities of radioactive material within an installation with a high *probability of significant public exposure.</dd></dl> <dl><dd>Examples:
- Sellafield (United Kingdom) ? 5 incidents 1955 to 1979<sup id="cite_ref-5" class="reference">[6]</sup>
- SL-1 Experimental Power Station (United States) ? 1961, reactor reached prompt criticality, killing three operators.
- Saint-Laurent Nuclear Power Plant (France) ? 1980, partial core meltdown.
- Buenos Aires (Argentina) ? 1983, criticality accident during fuel rod rearrangement killed one operator and injured 2 others.
- Jaslovsk? Bohunice (Czechoslovakia) ? 1977, contamination of reactor building.
- Tokaimura nuclear accident (Japan) ? 1999, three inexperienced operators at a reprocessing facility caused a criticality accident; two of them died.
<dl><dt>Impact on people and environment</dt><dd>Exposure in excess of ten times the statutory annual limit for workers.</dd><dd>Non-lethal deterministic health effect (e.g., burns) from radiation.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Exposure rates of more than 1 Sv/h in an operating area.</dd><dd>Severe contamination in an area not expected by design, with a low probability of *significant public exposure.</dd></dl> <dl><dt>Impact on defence-in-depth</dt><dd>Near accident at a nuclear power plant with no safety provisions remaining.</dd><dd>Lost or stolen highly radioactive sealed source.</dd><dd>Misdelivered highly radioactive sealed source without adequate procedures in place to handle it.</dd></dl> <dl><dd>Examples:
- THORP plant Sellafield (United Kingdom) ? 2005.
- Paks Nuclear Power Plant (Hungary), 2003; fuel rod damage in cleaning tank.
- Vandellos Nuclear Power Plant (Spain), 1989; fire destroyed many control systems; the reactor was shut down.
- Fukushima II Nuclear Power Plant (Japan), 2011, loss of cooling water in reactors 1, 2 and 4 after the 2011 Tōhoku earthquake and tsunami<sup id="cite_ref-IAEAtsunami1_6-0" class="reference">[7]</sup>
<dl><dt>Impact on people and environment</dt><dd>Exposure of a member of the public in excess of 10 mSv.</dd><dd>Exposure of a worker in excess of the statutory annual limits.</dd></dl> <dl><dt>Impact on radiological barriers and control</dt><dd>Radiation levels in an operating area of more than 50 mSv/h.</dd><dd>Significant contamination within the facility into an area not expected by design.</dd></dl> <dl><dt>Impact on defence-in-depth</dt><dd>Significant failures in safety *provisions but with no actual *consequences.</dd><dd>Found highly radioactive sealed orphan source, device or transport package with safety provisions intact.</dd><dd>Inadequate packaging of a highly radioactive sealed source.</dd></dl> <dl><dd>Examples:
- Blayais Nuclear Power Plant flood (France) December 1999
- Asc? Nuclear Power Plant (Spain) April 2008; radioactive contamination.
- Forsmark Nuclear Power Plant (Sweden) July 2006; backup generator failure.
<dl><dt>Impact on defence-in-depth</dt><dd>Overexposure of a member of the public in excess of statutory *annual limits.</dd><dd>Minor problems with safety components with significant defence-in-depth remaining.</dd><dd>Low activity lost or stolen radioactive source, device or transport package.</dd></dl> (Arrangements for reporting minor events to the public differ from country to country. It is difficult to ensure precise consistency in rating events between INES Level-1 and Below scale/Level-0)
<dl><dd>Examples:
- Gravelines (Nord, France), 8 August 2009; during the annual fuel bundle exchange in reactor #1, a fuel bundle snagged on to the internal structure. Operations were stopped, the reactor building was evacuated and isolated in accordance with operating procedures. <sup id="cite_ref-7" class="reference">[8]</sup>
- TNPC (Dr?me, France), July 2008; leak of 6,000 litres (1,300 imp gal; 1,600 US gal) of water containing 75 kilograms (170 lb) of uranium into the environment.
No safety significance.
<dl><dd>Examples:
- 4 June 2008: Kr?ko, Slovenia: Leakage from the primary cooling circuit.<sup id="cite_ref-8" class="reference">[9]</sup>
- 17 December 2006, Atucha, Argentina: Reactor shutdown due to tritium increase in reactor compartment.<sup id="cite_ref-9" class="reference">[10]</sup>
- 13 February 2006: Fire in Nuclear Waste Volume Reduction Facilities of the Japanese Atomic Energy Agency (JAEA) in Tokaimura. <sup id="cite_ref-10" class="reference">[11]</sup>
http://en.wikipedia.org/wiki/International_Nuclear_Event_Scale