here - Atomic Energy Regulatory Board

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Figure 2.1: International Nuclear Event Scale (INES)
Level/
Descriptor Nature of the Events Examples
7 • Major release: Widespread health and Chernobyl NPP, USSR
MAJOR ACCIDENT environmental effects (now in Ukraine), 1986
6 • Significant release: Likely to require full Kyshtym Reprocessing Plant, USSR
SERIOUS ACCIDENT implementation of planned counter measures (now in Russia), 1957
5 • Limited release: Likely to require partial Windscale Pile, UK, 1957
ACCIDENT WITH implementation of planned counter measures
OFF-SITE RISK • Severe damage to reactor core/ Three Mile Island, NPP, USA, 1979
radiological barriers
4 • Minor release: public exposure of the order Windscale Reprocessing
ACCIDENT WITHOUT of prescribed limits Plant, UK, 1973
SIGNIFICANT • Significant damage to reactor core/radiological Saint-Laurent NPP, France, 1980
OFF-SITE RISK barriers/ fatal exposure of a worker Buenos Aires Critical Assembly,
Argentina, 1983
3 • Very small release: public exposure at a Vandellos NPP, Spain, 1989
SERIOUS INCIDENT fraction of prescribed limits
• Severe spread of contamination/ acute health
effects to a worker
• Near accident, no safety layers remaining
2 • Significant spread of contamination/ over
INCIDENT exposure of a worker
• Incidents with significant failures in
safety provisions
1 • Anomaly beyond the authorized
ANOMALY operating regime
0
DEVIATIONS No safety significance
BELOW SCALE
The number of SERs for each year from 2001-2002 to 2005 and their ratings on INES are given in Table 2.6. In the
year 2005, a total of 28 significant events were reported from the operating NPPs. In the year 2004, the number of significant
events was 44. The classification of SERs for the year 2005 on INES scale is given in Table 2.7.