Image via WikipediaAn April 13, 2011 press release prepared by the Department of Foreign Affairs
The Philippine Permanent Mission to the United Nations in Vienna reported to the Department of Foreign Affairs (DFA) that in a briefing for the diplomatic missions in Vienna on April 12, Tuesday, the International Atomic Energy Agency (IAEA) stated that the change in rating from Level 5 in the International Nuclear and Radiological Event Scale (INES) to Level 7 for the Fukushima Dai-ichi Nuclear Power Plant issued by the Japanese Nuclear and Industrial Safety Agency (NISA) does not imply that the situation has become graver now compared to the days immediately following the accident.
It simply implies that there is more information now available to the Japanese authorities on the amount of radioactive release (owing to the more systematic monitoring in place) to enable it to make an assessment of the appropriate provisional rating.
The provisional rating was determined by NISA after it received the results of the analysis conducted by the Japan Nuclear Energy Safety Organization, which estimated the total amount of radioactivity released to the environment. NISA estimates that the amount of radioactive material released to the atmosphere is approximately 10% of the 1986 Chernobyl accident, which is the only other nuclear accident to have been rated a Level 7 event.
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 the three Units. The provisional INES Level 3 rating assigned for Unit 4 still applies.
INES, which now has 70 participating States including the Philippines, was developed in 1990 by experts convened by the IAEA and the Organization for Economic Cooperation and Development with the aim of communicating the safety significance of events. It serves as a tool which aims to communicate to the public in consistent terms the safety significance of reported nuclear and radiological incidents and accidents, excluding naturally occurring phenomena. The scale can be applied to any event associated with nuclear facilities, as well as the transport, storage and use of radioactive material and radiation sources.
Events are classified at seven levels: Levels 1-3 are “incidents” and Levels 4-7 “accidents.” These levels consider three areas of impact: people and the environment, radiological barriers and control, and defense in depth. The scale is designed so that the severity of an event is about ten times greater for each increase in level on the scale. The levels are 1 (anomaly), 2 (incident), 3 (serious incident), 4 (accident with local consequences), 5 (accident with wider consequences), 6 (serious accident), and 7 (major accident).
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