Page 59 - AERB

1.8 SIGNIFICANT EVENTS on INES. Events rated at levels 1, 2 and 3 are called
‘Incidents’. The level 0 or below scale means events that
AERB requires NPPs to report certain events that have no nuclear and radiological safety significance.
occur in the plant which have or may have impact
on operational safety. Under the reporting system 1.8.1 Significant Events and INES rating of NPP
established by AERB, the events reportable to AERB are
divided into two categories, termed as, All the significant events reported were reviewed in
detail by AERB and measures to prevent recurrence of
(a) Events such events were recommended.

(b) Significant Events (i) Significant Events in NPPs under Construction
This categorization of events is done based on During the year no significant event was reported in
their safety significance and importance to operational NPP under construction.
safety experience feedback. Based on the established
reporting criteria, Event Reports (ER) and Significant (ii) Significant Events in Operating NPPs
Event Reports (SER) are submitted to AERB. The During 2019, a total of 45 significant events
SERs received from the operating NPPs are rated were reported from operating NPPs. Out of these, 40
on the International Nuclear and Radiological Event significant events were rated at level 0 and one event (at
Scale (INES) of International Atomic Energy Agency RAPS-2) was rated at level 1 on INES. INES rating of
(IAEA). The INES rates events at seven levels (1 to one event at TAPS-3&4 is under review at AERB.
7) depending on their safety significance as shown in
figure 1.7 below. Three significant events, one each at RAPS-5&6,
KGS-1 and KKNPP-1&2 were not rated on INES as these
Events rated at level 4 and above are termed as were related to industrial safety and had no relevance
‘Accidents’. The accidents at Chernobyl NPP in former to nuclear and radiological safety. The number of SERs
USSR (now in Ukraine) in April 1986 and Fukushima in each NPP and their ratings on INES are given in
NPPs in Japan in March 2011 were rated at level 7 Table-1.12.

Major Accident
7 Serious Accident
ACCIDENT 6 Accident with wider

5 4 consequences

Accident with local
consequences
Serious incidents
3
INICIDENT 2 1 Incidents

Anomaly

Below Scale/ Level 0
No Safety Significance

Fig. 1.7: INES Scale

AERB Annual Report 2019 31