Posted on 04/11/2011 10:37:36 PM PDT by topher
IAEA Update on Fukushima Nuclear Accident (12 April 2011, 4:45 UTC)
The Japanese Nuclear and Industrial Safety Agency (NISA) today issued a new rating for the accident at the Fukushima Daiichi nuclear power plant on the IAEA International Nuclear and Radiological Event Scale (INES).
The nuclear accident at Fukushima Daiichi is now rated as a level 7 "Major Accident" on INES. Level 7 is the most serious level on INES and is used to describe an event comprised of "A major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures".
The new provisional rating considers the accidents that occurred at Units 1, 2 and 3 as a single event on INES. Previously, separate INES Level 5 ratings had been applied for Units 1, 2 and 3. The provisional INES Level 3 rating assigned for Unit 4 still applies.
The decision to rate the Fukushima accident to a level 7 "Major Accident" is a reclassification of an earlier assessment of the accident.
The re-evaluation of the Fukushima INES rating resulted from an estimate of the amount of radioactivity released to the environment from the nuclear plant. NISA estimates that the amount of radioactive material released to the atmosphere is approximately 10 percent of the 1986 Chernobyl accident, which is the only other nuclear accident to have been rated a Level 7 event.
Previous INES ratings at the Fukushima Daiichi nuclear power plant were assessed on a per-case basis at each nuclear power plant unit. Japanese authorities have now classified the nuclear accident as a singular event on INES.
Earlier ratings of the nuclear accident at Fukushima Daiichi were assessed as follows:
On 18 March, Japanese authorities rated the core damage at the Fukushima Daiichi 1, 2 and 3 reactor Units caused by loss of all cooling function to have been at Level 5 on the INES scale. They further assessed that the loss of cooling and water supplying functions in the spent fuel pool of the Unit 4 reactor to have been rated at Level 3.
Japanese authorities may revise the INES rating at the Fukushima Daiichi nuclear power plant as further information becomes available.
INES is used to promptly and consistently communicate to the public the safety significance of events associated with sources of radiation. The scale runs from 0 (deviation) to 7 (major accident).
For further information on the INES scale: http://www-ns.iaea.org/tech-areas/emergency/ines.asp
NISA estimates that the amount of radioactive material released to the atmosphere is approximately 10 percent of the 1986 Chernobyl accident, which is the only other nuclear accident to have been rated a Level 7 event.
At this point, it is 10% of Chernobyl, but there are six reactors and quite a bit of fuel. It is under control for the moment; however, the area is being hit with fairly large aftershocks still (6.2 off Tokyo tonight).
25th year Anniversary of Chernobyl is now two weeks away: occurred on 26-April-1986.
Atmosphere. How about adding aquatic release ?
Maye they should have called it a 6.1 if it is ten time less.
Maye they should have called it a 6.1 if it is ten time less.
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