Power Reactor
| Types of facilities | ||
|---|---|---|
 INES 2 |
Loss of shutdown cooling due to station blackout during refueling outage |
On February 9, 2012, during a refueling outage, loss of off-site power (LOOP) occurred and emergency diesel generator (EDG) 'B' failed to start while EDG 'A' was out of service for scheduled maintenance, resulting in a station blackout (SBO). Off-site power was restored 12 minutes after the SBO condition began.
The LOOP was caused by a human error during a protective relay test of the main generator. The EDG 'B' failing to start was caused by the failure of the EDG air start system.
INES 1 |
Fire and abnormal primary circuit leak occured at Penly NPP n°2 reactor |
On 5 April 2012, at around 12 midday local time, ASN was informed by the operator EDF that a fire had started in the n°2 reactor building of the Penly NPP (North-West of France). The reactor automatically shut down.
EDF teams and the local firemen brigades entered the reactor building and extinguished burning oil. The firemen ensured the fire was totally extinguished.
INES 2 |
Failure of the reactor component cooling water system and others by tsunami |
Unit 2 of the Onagawa Nuclear Power Station started operation since 14:00 on March 11, and the Tohoku District – Off the Pacific Ocean Earthquake occurred at 14:46 on the same day. The reactor was automatically stopped and emergency diesel generator A (EDG (A)), emergency diesel generator B (EDG (B)), and high-pressure core-spray diesel generator (EDG (H)) automatically started.
INES 2 |
Level 2 incident on INES scale concerning a pipe nonconformity in two Cattenom NPP fuel storage pools |
On 18 January 2012, Cattenom's operator (EDF) notified ASN that the absence of a \siphon breaker\ orifice on the fuel storage pools of reactors 2 and 3 had been detected during an inspection performed by EDF teams.
INES 1 |
Leakage of Heavy Water from Feeder Pipe |
Plant was in shutdown state since October 05, 2011 because of maintenance activities. As per normal procedure during shutdown state, Standby Cooling System (SH) was in service to remove decay heat from the reactor core while Primary Heat Transport (PHT) system was in depressurized state. On October 19, 2011, inspection of channel S-11 grayloc seal was carried out to find out any foreign material in the orifice. During normalization of the system, Boiler Room (B/R) floor beetle alarm received in control room. Later, 'Tritium in Air High' alarm also annunciated.
INES 0 |
Alert Emergency Action Level Declaration due to Loss of Offsite Power Resulting from a Seismic Event |
On 23 August 2011, Units 1 and 2 of the North Anna Power Station declared an Alert, Emergency Action Level due to a loss of offsite power following a 5.8 seismic event on the Richter Scale. As of August 24, 2011, Unit 1 and Unit 2 are proceeding to cold shutdown conditions to allow for inspections inside containment. Normal offsite power has been restored to the North Anna Power Station.
At 1403 (EDT), on August 23, 2011, Units 1 and 2 of the North Anna Power Station declared an Alert, Emergency Action Level due to a loss of offsite power.
INES 2 |
Over exposure of workers beyond annual regulatory limit |
Kakrapar Atomic Power Station (KAPS) is a twin unit station with 220 MWe Pressurized Heavy Water Reactors. Refueling of these reactors is done when the reactor is on-power. The spent fuel bundles discharged from the reactor are transferred to Spent Fuel Storage Bay (SFSB) through the Spent Fuel Transfer Duct (SFTD). The radiation field in the SFTD area goes high during transfer of spent fuel bundles through SFTD.
On May 30, 2011, Unit-2 of KAPS was operating at 98% FP. For carrying out painting job, SFTD shielding blocks were removed.
INES 7 |
Re-evaluation of INES rating; Effect to the Nuclear Facilities from the earthquake on east area of Japan |
In March 18, rating of the INES on the events in Fukushima Dai-ichi Nuclear Power Station, by the Tohoku Regional Pacific Ocean Offshore Earthquake is temporary estimated Rating 5. However, Nuclear and Industrial Safety Agency (NISA) estimated total amount of discharge from Fukushima Dai-ichi NPS, using the analytical result of the state of nuclear reactor under the cooperation of Japan Nuclear Energy Safety Organization (JNES). As a result of re-evaluation, total amount of discharged I131 is estimated at 1.3E17Bq, and Cs137 is estimated at 6.1E15Bq.
INES 2 |
Inadequate setting of the auxiliary feedwater turbopump |
After the replacement of an auxiliary feedwater turbopump during the 2009-outage, the rotational speed of the pump was adjusted to a lower level because of vibration problems with the pump. The pump was tested and requalified according to the technical specifications but the curve (flow-rate <-> pressure) was not verified as required by ASME-XI. The actual flow rate delivered in case of specific accidents could no longer match the flow rate postulated in the safety report. Nevertheless, an independent emergency feedwater system could offer additional capacity in such circumstances.
INES 3 |
Loss of the cooling function to the ultimate heat sink due to the big tsunami |
Fukushima Dai-ni Nuclear Power Station Units 1, 2 and 4, which is in rated power operation, have automatically shut down around 14:46(JST) on March 11, 2011, because of the Tohoku regional Pacific Ocean Offshore Earthquake. Following the earthquake, the big tsunami attacked the power station and the seawater pump rooms were flooded. The licensee lost the function operability of sea water pumps for last heat removal. The turbine driven pump started operation and the exhausted steam increased the pressure of the suppression pool.
