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)
Javascript is required to view this map.
INES-event
INES 1

PLUTONIUM RECOVERY PLANT, B204

An abnormal discharge of plutonium amounting to 600 MBq over 2 days took place via the ventilation system and discharge stack from a redundant plutonium recovery plant. The current best estimate of dose to the potentially most exposed member of the public is about 1 microSv.
An investigation is underway to determine the cause of the release.

Category: Fuel Reprocessing Sellafield United Kingdom »

INES-event
INES 1

PVNGS 2 STEAM GENERATOR TUBE RUPTURE

Palo Verde Unit 2 was operating at 98 percent power. At 0435, operators noticed a decrease in pressurizer pressure and level. Although additional charging flow was started, pressurizer level and pressure continued to decrease. The operators manually scrammed the reactor at 0447. Safety injection and containment isolation signals automatically initiated. After determining that a steam generator tube rupture existed, operators began to cool down and depressurize the reactor coolant system. The leak rate was estimated to be approximately 15 l/s (240 gal/min.).

Category: Power Reactor United States of America »

INES-event
INES 1

COOLANT RADIOACTIVITY EXCEEDING OPERATING LIMITS DUE TO FUEL ROD FAILURE

Angra-1 had been experiencing some small fuel rods leakage since 4 months with primary water coolant activity indicating some percentage of Tech. Spec. limits. In 93.03.05 during a normal operation at 50% rated power a routine surveillance of reactor coolant activity detected values greater than the corresponding limiting conditions for operation. According to required actions the plant was immediately shut down following normal procedures. Preliminary estimations pointed out that around 100 fuel rods had failed. The utility is preparing defueling the core and inestigating the causes.

Category: Power Reactor Brazil »

INES-event
INES 1

CRACKS IN PIPEBENDS (ELBOWS) IN THE RESIDUAL HEAT REMOVAL SYSTEM

During shutdown cracks were found in two elbows in the residual heat removal system. These elbows were located between one isolation valve and the reactor vessel. The cracks were probably caused by IGSCC (Intergranular Stress Corrsion Cracking) which has been observed earlier in cold formed bends. The material is austenitic stainless steel SS 2333-25. No heat treatment has followed the manufacturing.

Category: Power Reactor Oskarshamn Sweden »

INES-event
INES 1

UNITS DERATED TO 60% REACTOR POWER DUE TO SAFETY ANALYSIS CONCERNS

Ontario Hydro has reduced power at Bruce Nuclear Power Development to 60% full power as a result of analysis of very low probability accidents being studied as part of a solution to pressure tube fretting. The analysis identified potential for an increase in reactivity from the sudden relocation of the fuel string due to reverse hydraulic loading during a large reactor inlet header rupture. The power reduction provides a significant margin of conservatism to compensate for the maximum accepted reactivity increase for this scenario.

Category: Power Reactor Canada »

INES-event
INES 1

SOIL CONTAMINATION WHILE PUMPING OUT RAIN WATER FROM TAPS-TRAP TRANSFER LINE INSPECTION PIT

Due to heavy rains the TAPS-TRAP (Tarapur Radwaste Augmentation Plant) transfer line inspection pit no. 1 got filled. Water sample was collected from inspection pit no. 1. As the activity was found to be below detectable limit the water was cleared for pumping out. While pumping out the discharge line hose gave way and some amount of water got leaked into the adjacent grass soil. Health physics survey of the area indicated that the soil near the pit was contaminated and having about 0.5 mGy/hr radiation field.

Category: Power Reactor India »

INES-event
INES 1

TRITIUM RELEASE DUE TO SPILLAGE OF HEAVY WATER FROM MODERATOR SYSTEM

Unit was under cold shutdown. Moderator was in dumped condition. While normalising moderator system, a temporary ion exchange column was hooked up on series with normal purification IX column. This was connected by reinforced PVC hose. 15 minutes after valving in the additional column, the hose was found to have come out resulting in spillage of heavy water which resulted in higher Tritium concentration in accessible areas. Reactor Building exhaust fan with higher capacity was started to reduce the Tritium concentration.

Category: Power Reactor India »

INES-event
INES 1

TRITIUM ACTIVITY DISCHARGE TO LAKE

Process water return sampling indicated presence of tritium in T.B. (Turbine Building) pit. Investigations were started as per the approved procedure. The unit was shut down for further investigation as all efforts failed to detect the source on power. The cause of the incident is suspected to be the water overflow from the Dousing tank. (Dousing tank water picks up tritium activity from boiler room environment.)
Justification: As per the users manual clause III 3.7 and III 5.3 (repeat incident) it is rated at level 1.

Category: Power Reactor India »

INES-event
INES 1

INDICATIONS IN AUSTENITIC PIPING DISCOVERED DURING NON-DESTRUCTIVE TESTING

Brunsbuettel NPP is in refuelling outage since August 25, 1992. As action taken after discovery of cracks in austenitic piping in KWW NPP extensive non-destructive testing of welds in austenitic piping of systems connected to the reactor pressure vessel had been scheduled. By this testing a large number of indications has been discovered mainly in the reactor water cleanup system and the pressurized bearing water system for the internal circulation pumps. Investigation on indications and causes has been started but not yet completed.

Category: Power Reactor Brunsbüttel Germany »

INES-event
INES 1

SMALL STEAM LEAK FROM THE MAIN FLANGE OF THE PRIMARY COOLANT PUMP NO. 4

The event occurred at Kozloduy Npp - Unit 2, on 2 January 1993. Unit 2 was operated at 60 % rated power. A small steam laek from the main flange of the primary coolant pump no. 4 was discovered. The beta gas specific activity measured in the pump room was 0.5E-9 Ci/l. In accordance with the regulatory body special regime for operation of units with VVER-440/230 reactors, Unit no. 2 was shut down for repair of the primary coolant pump no. 4 main flange. No increase of the radioactive release from the plant's stack was detected.

Category: Power Reactor Bulgaria Kozloduy »