1

INES Levels
INES N/A 
INES 4
INES 0
INES 5
INES 1
INES 6
INES 2
INES 7
INES 3

INES 1: Anomaly

Impact on Defence-in-Depth
  • Overexposure of a member of the public in excess of statutory ­annual limits.
  • Minor problems with safety components with significant defence-in-depth remaining.
  • Low activity lost or stolen radioactive source, device or transport package.
(Arrangements for reporting minor events to the public differ from country to country. Also, it is difficult to ensure precise consistency in rating events between INES Level-1 and Below scale/Level-0)
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INES-event
INES 1

DEGRADATION OF NATURAL CIRCULATION

Refuelling of Unit 4 was commenced on 18 June 1988. Operating personnel performed a planned switchover to natural circulation from loops 4 and 6 to loops 1 and 3 on 30 June. Meanwhile, the effectiveness of core cooling by natural circulation decreased sharply for about a 3 hour period. After switching over the natural circulation among the llps, the operating personnel isolated loops 4 and 6 and started to drain them. Nitrogen used to drain the water got into the loops in operation and most of the water was pushed from the SG primary side into the reactor vessel.

Category: Power Reactor Hungary Paks »

INES-event
INES 1

REACTOR COOLANT LEAK ON REACTOR TEMPERATURE DETECTOR

Reactor coolant System Leakage of 280 Lit/H Upper Technical Specifications Limit (227 L/H). The leakage was located in a flowmeter on the reactor temperature detector (RTD) Line (loop A). The leakage was initatied at 21.15 hrs. (July 7) and isolated at 20.30 hrs (July 8). The plant remained in hot shutdown operation mode. The total leakage was 7.000 litres.
BASIS FOR RATING: Initiator frequency: Expected, real
Safety function availability: full
Insignificant on site impact inside containment. No off-site impact.
DIFFICULTIES IN RATING:

Category: Power Reactor Spain Vandellòs »

INES-event
INES 1

FEEDWATER TUBE RUPTURE DUE TO EROSION CORROSION

One pipe of the feedwater system of Loviisa 1 broke. The ruptured tube was situated in the turbine hall of the unit. Water and steam flew into the turbine hall. The operation of the Unit was stopped by a manual reactor scram immediately after trip of all feedwater pumps. Both auxiliary feedwater pumps started as planned and the transient in the steam generator level was small. The leak was isolated in about twenty minutes. The local damages to nearby cables and smaller pipelines were significant but no important functions were lost besides the main feedwater system.

Category: Power Reactor Finland Loviisa »