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

MISGRAPPLING OF FUEL BUNDLE MB-140 IN THE CORE OF UNIT NO. 2

While catching the bundle MB-140 in the core with fuel grapple, the nose of the hook went inside the bail, and hook open-close operation was not taking place. After giving 'Open' signal to the grapple the grapple was lifted up and the operator found the fuel bundle hanging on the nose. To provide additional support and to secure the bundle in its position, the bundle was caught on the bail with a 'J' hook and was lowered on the channel stripping machine in the fuel pool.

Category: Power Reactor India »

INES-event
INES 1

FAILURE OF FUEL OIL LINE IN RUNNING DG-2

DG-2 of unit 2 was running on isolated, Class III bus in view of ACVR-2 shut down as per Technical Specifications. At 02.00 hrs. of 3.5.91, fuel oil leak was observed in the fuel oil cylinder supply line ferrule joint of the running DG-2. Since the leak was heavy, DG-2 was stopped after connecting 5231 Bus-Q to Class IV source through 5231-TR-2.
BASIS FOR RATING: According to Table I, C-2P, level 1 or 2 can be selected. Since the problem was attended quickly and back up from diesel generator of the other shut down unit was available, level I is selected.
DIFFICULTIES IN RATING:

Category: Power Reactor India »

INES-event
INES 1

FUEL ASSEMBLY TILTED OVER DURING CORE LOADING

During core loading a fuel assembly was not properly seated on the lower core plate. Zero load was obtained with the assembly standing on top of the two guide pins which are supposed to enter the foot piece of the fuel assembly. The gripper of the manipulator was released and at this moment the fuel assembly fell over towards the baffle. No damages were caused to neighbouring assemblies or reactor internals and no activity release was observed.

Category: Power Reactor Ringhals Sweden »

INES-event
INES 1

FUEL BUNDLE LATTICE SPACING FAILURES

The Loviisa fuel bundles have ten spacing latices. The on-site examinations of spent fuel have revealed deformation and relocation of the uppermost lattice. The extent and the consequences of this failure mode are being evaluated.
BASIS FOR RATING: Safety function availability: full. Real initiator: fuel bundle spacinglattice failure. Initiator frequency: Possible. Table A2 gives 1.
DIFFICULTIES IN RATING:

Category: Power Reactor Finland Loviisa »

INES-event
INES 1

UNIT SHUTDOWN DUE TO PERSONNEL ERRORS AND DAMAGE TO RCP 6 KV BREAKER

In the course of repairing a defect in the oil line of auxiliary house transformer the latter was tripped by protection. The unit was shut down. The cause of protection actuation was personnel error. Six hours later while starting RCP-1 short-circuit in the 6 kV breaker cabinet of this pump has occurred due to loss of contact in the breaker phase. The resulting smoke was extinguished by operating personnel in 15 minutes. After replacement of the damaged breaker on 2.6.91 the unit was raised to the minimum controlled power level.

Category: Power Reactor Kalinin Russian Federation »

INES-event
INES 1

UNPLANNED EXPOSURE OF PERSONNEL DURING REFUELLING

On 11 May at 6.05 pm when the Reactor Core Hold Down was elevated for the refuelling of the reactor, two assemblies of the System for Neutron Flux Monitoring stuck and then fell down on the Control Rod Protection Tubes. The exposure rate measured in the Reactor Hall was in the range of 0.4 mSv/h to 1.3 Sv/h in the immediate proximity of the assemblies. Twenty three workers were exposed. The dose to the most exposed individual was 12.5 mSv.

Category: Power Reactor Bulgaria Kozloduy »

INES-event
INES 1

TURBINE SJAES STEAMING DUE TO PLANT PERSONNEL ERROR

The unit was operating at nominal power. Thermal Instrumentation and Controls Service (TICS) shift personnel admitted TICS maintenance personnel to perform work on hydrogen content monitoring sensors at the outlet of moisture separator of the hydrogen reburn facility without informing Turbine Service operating personnel and plant deputy shift supervisor. While performing work on one of the sensors spurious signal of hydrogen concentration increase to 0.4% was formed.

Category: Power Reactor Russian Federation Smolensk »

INES-event
INES 1

UNIT SHUTDOWN DUE TO SG-4 PULSE LINE RUPTURE

Unit shutdown occurred due to the rupture of the pulse line measuring pressure in SG-4 steam header. Pulse line damage occurred because of design deficiency in the routing and fixing the pulse line during SG replacement.

Category: Power Reactor Novovoronezh Russian Federation »

INES-event
INES 1

WRONG POSITIONING OF THE FUEL ASSEMBLY WHILE PERFORMING FUEL ROD CLADDING INTEGRITY TEST

While performing fuel rod cladding integrity test of the removed fuel, the fuel assembly was erroneously placed in the abnormal position on the plate of the testing system flasks and disconnected from the refueling machine telescopic beam. Later the above fuel assembly was placed in the testing system flask. Inspection of the fuel assembly did not reveal any damage.
BASIS FOR RATING: Initiator - fuel assembly handling in the wrong position.
Criterion - degradation of defence-in-depth.

Category: Power Reactor Kola Russian Federation »

INES-event
INES 1

PRESSURIZER DISCHARGE TANK MEMBRANE RUPTURE

On 5 February 1991 at 12.00 pm during the routine survey of the reactor compartment a ruptured membrane of the pressurizer discharge tank was discovered. The gas-aerosol activity near the discharge tank was measured 3 x 10-8 Ci/l, and the activity in the hermetic steam generator box was measured 8 x 10-9 Ci/l. A possible reason for the rupture of the membrane is a routine blowing away of the hydrogen in the pressurizer by means of low-pressure nitrogen.

Category: Power Reactor Bulgaria Kozloduy »