INES 0: Deviation
No safety significance
(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)
 INES 0 |
Malfunction of the feedwater control valve caused reactor trip |
Prior to the event the plant was in steady state operation (mode 1) at 84% rated power. All systems were operable as required for this mode.
INES 0 |
Core instability occurred during maintenance performed in the switchyard |
During maintenance, performed in the switchyard, a false signal showing "generator disconnected" was transmitted to the power control system. As the signal aspect was considered unclear, partial scram (one group of control rods inserted) was manually started. However, depending on faulty reheater control, the feed water temperature dropped, leading to increasing reactor power.
INES 0 |
Fire in emergency diesel generator control panel during test |
On 8 October, 1998, with the unit in day 33 of a refueling outage, an ALERT emergency classification was declared due to an electrical fire in the local control panel for the #12 emergency diesel generator (EDG). At the time of fire, the licensee was performing a 24 hour surveillance test of EDG following a major overhaul of the diesel engine. The local EDG operator noticed heavy smoke coming from the control panel and tripped the EDG and opened its output breaker before leaving the area.
INES 0 |
Reactor trip breaker train B undervoltage card damage |
Prior to the event the plant was operating stable at 100% power, generator output was 647MWe. All operating parameters were stable and inside the normal operating range. All safety and other significant components were operable; all Protection and Control systems were in function. In progress was a surveillance test according to procedure SMI-4.050, Surveillance Actuation Logic Test SSPS Train B. According to this procedure Reactor Bypass Trip Breaker B was closed. After the simulated signal for Pressurizer High Pressure Trip, Reactor Trip Breaker B opened as it was expected.
INES 0 |
Small short-term fire in the electric rectifier in the NPP Dukovany |
On Tuesday, July 28, 1998 at 4.00 a.m. a small short-term fire occurred in the nuclear power plant Dukovany unit 1. A part of the support electric rectifier (EQ 08B) was inflamed, the event was signalled and the fire brigade extinguished it at 4.05 a.m. The unit 1 was in shutdown in this time (25 days of refuelling). No impact on nuclear safety and on health of people was noted. The loss was assessed no more than 30 USD. The information was released to press and is reported to the INES because of possible public interest.
INES 0 |
Reactor trip resulting from fast acting scram system (FASS) actuation |
On 3 March 1998 unit 1 was in normal operation with thermal power of 2200 MW (equal to 50% of normal).
At 12.48 when the reactor control and protection system was subject to planned activity there was a spurious signal which actuated the Fast Acting Scram System (FASS) resulting in reactor trip. The spurious signal causes are currently under investigation.
Justification:
The fast reactor trip is an expected initial event. There is full availability of safety functions. This event is preliminarily classified on INES at level 0 according to Table II (A-1) INES user's manual
INES 0 |
Loss of shutdown cooling |
On 13 February 1998, shutdown cooling of the reactor vessel was lost for several hours when suction isolation valves for the residual heat removal (RHR) system automatically closed. These valves closed due to the loss of the primary power supply to Division 2 of the Nuclear Safety Protection System, while the alternate power supply was unavailable because of maintenance. The unit had been shut down since 5 September 1996, and decay heat loads were relatively low.
INES 0 |
Small short-term fire in the switchboard in the NPP Dukovany |
On Sunday, November 9, 1997 at 10:40 a.m. a small short-term fire occurred in the nuclear power plant Dukovany. The fire brigade after signalling found that the fire was automatically extinguished by protection. After assessment of the event by specialists the switchgear was in opeation without limitations. The loss was assessed about 60 USD. No impact on nuclear safety and on the operation of the nculear power plant was noted. The Information was released to press and media and is reported to the INES because of possible interest of the public.
INES 0 |
Fire in emergency diesel generator exhaust |
On October 9, 1997, Limerick 2 experienced a fire in the exhaust stack of the D21 emergency diesel generator (EDG) during an operability test. The unit was operating at 100% power at the time of this event. During the test run, the #4 cylinder lower piston seized, resulting in damage to the piston, connecting rod and cylinder liner. The fire occurred due to the release of unburnt fuel into the EDG exhaust manifold and exhaust stack. The fire burned out when the EDG was secured. A second, smaller, fire occurred on the body of the EDG in the vicinity of the exhaust manifold.
INES 0 |
Fire incident in boiler room |
While monitoring boiler room through CCTV during plant start-up, flames were observed in the vicinity of one of the main coolant pumps. Reactor was immediately shut down, and primary heat transport system crash cooled to 300 deg. F. Shift fire fighting crew rushed to the affected area to extinguish the fire. At the fire site it was observed that the insulating material of the piping close to the main coolant pump was burning.
