Event Notification Report for May 01, 2000

DAMAGED TROXLER MOISTURE DENSITY GAUGE

Montana Dept of Transportation reported a damaged Troxler moisture density gauge containing 8 mCi Cs-137 and 41 mCi Am- 241. The gauge fell out of the back of a truck and was retrieved. The gauge case was cracked but the source was intact. The area was surveyed and a wipe test was performed with no leakage detected. The licensee presently plans to repair the damaged gauge case.

UNIT 1 EXPERIENCED AN AUTOMATIC REACTOR SCRAM DUE TO A TURBINE TRIP/GENERATOR LOCKOUT ON ELECTRICAL FAULT

"At 0307, Unit 1 Reactor automatically shutdown from 92% power. The shutdown was the result of a Turbine Trip/Generator Lockout caused by an electrical fault on the '1C' Main Transformer. All Rods fully inserted (RPS), and the plant is in Hot Shutdown (opcon 3). Level is currently at normal operating level. The following isolations were received; Main Steam and Rx Sample (1B), Reactor Water Clean-Up (3), Primary Containment Purge Supply and Exhaust (6a), Primary Containment Exhaust to REECE (6b), Drywell Sump, Suppression Pool Cleanup, and Tips (8b), and Reactor Enclosure HVAC. The isolations were received due to a NSSSS 'Reactor Level 2 - Low Low' signal during the event. All plant systems operated as designed. The cause of this event is currently being investigated by plant staff."

Unit 1 will remain in Opcon 3 pending the results of the investigation. No SRVs cycled during the transient. Offsite power and EDGs are available. The extent of repairs to the main transformer has not been determined. A preliminary inspection shows a bus bar connection missing.

The licensee informed state/local authorities and the NRC Resident Inspector.

- SAFEGUARDS EXHAUST VENTILATION SYSTEM UNABLE TO FULFILL ITS SAFETY FUNCTION -

While reviewing the test results of the newly revised safeguards exhaust ventilation (SEV) System discharge damper seismic air flask leakage surveillance test [1(2)-PT-77.12A(B)], the licensee determined that the test results indicate that the SEV System was in a condition that alone could have prevented the system from fulfilling its safety function. The seismic air flask equipment and damper degradations, coupled with a loss of instrument air during a loss of coolant accident, could have prevented the control of leakage of radioactive material from safeguards equipment, as well as cooling for the recirculation spray and low head safety injection pumps located in the safeguards building (residual heat removal capability).

Currently, the systems have been repaired and are fully operable. JCO #00-01 has been prepared and implemented to provide additional guidance on appropriate operator actions to restore air to the seismic air flasks to assure continued system operation.

The new test techniques and requirements were the result of an ongoing in-depth licensee engineering review of the North Anna plant ventilation systems.

The licensee notified the NRC Resident Inspector.

NRC BULLETIN 91-01 CRITICALITY CONTROL, 4 HOUR REPORT -

At 1340 on 05/01/00, it was discovered that an NCSA-0705-076.A00 control was not in place. Insulation on non-uranium bearing pipes in the vicinity of uranium bearing solution piping and systems was not sealed. The insulation could accumulate uranium bearing solution in an unfavorable geometry in the event the integrity of the nearby uranium bearing solution lines was to be lost. Geometry control specified in NCSA-0705-076.A00 was not maintained in reference to the piping insulation.

The control cannot be restored within a 4 hour time frame and is therefore being submitted as a 4 hour reportable event. Operations/solution processing in the area has been secured. All fissile material operations are suspended in the X-705 operation area pending corrective actions.

The loss of this control resulted in a condition in which only one control of the double control contingency was maintained.

SAFETY SIGNIFICANCE OF EVENT:
The insulation in use covers non-uranium bearing lines (water & steam). In addition, the insulation forms an annulus, which does not have complete cross section as compared to a cylinder. None of the nearby systems experienced a leak which could have resulted in solution entering the absorbent material. Therefore, the safety significance of this event is low.

POTENTIAL CRITICALITY PATHWAYS INVOLVED [BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR]:
If a large leak developed in a nearby uranium-bearing system, the absorbent insulation could have accumulated a large amount of material in an unsafe geometry.

CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC):
The controlled parameters were geometry and the physical integrity of the nearby uranium-bearing systems.

ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE OF CRITICAL MASS):
No uranium-bearing material was involved with this situation. Some of the areas which involved the insulation handles highly concentrated solutions. The high-bay area currently has a uranium-bearing concentration of 69 ppm U based on prior sampling reports.

NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES:
The absorbent material was not covered or modified such that the geometry was favorable.

CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEM AND WHEN EACH WAS IMPLEMENTED:
Fissile material operations in the affected area have been suspended pending further investigation and subsequent corrective actions.

The NRC Resident Inspector and the Site DOE Representative have been notified of this event.

- OFFSITE AGENCIES NOTIFIED OF FREON GAS RELEASE TO THE ATMOSPHERE FROM UNIT 3 -

The licensee notified the California Office of Emergency Services, San Diego Department of Environmental Health and San Diego Air Pollution Control District that approximately 3000 pounds of freon gas had escaped into the atmosphere from a failed relief valve on a Unit 3 air conditioner (chiller).

The licensee plans to notify the NRC Resident Inspector.

24-HOUR NRC BULLETIN 91-01 REPORT INVOLVING NUMEROUS NUCLEAR CRITICALITY SAFETY ANALYSIS (NCSA) VIOLATIONS IDENTIFIED IN X-705 BUILDING WALKDOWN

"On 4/28/00, a manager reported (PR-PTS-00-02234) a potential adverse trend with inadvertent containers (NCSA-705_076.A00) in the X-705 Building. All fissile material operations were suspended in the X-705 operation area pending assessment of PR-PTS-00-02234.

"In response to PR-PTS-00-02234, a systematic walk down was performed 5/1/00 for the presence of inadvertent containers in the X-705 Building. At 1034 hours the first NCSA-705_076.A00 violation was identified. Further violations were identified throughout the day for a total of seventeen (17). All were immediately corrected with Nuclear Criticality Safety (NCS) engineer guidance. These violations could have resulted in the potential accumulation of an unsafe volume of solution had a leak developed with nearby uranium bearing systems.

"Twelve (12) violations were with NCSA-705_076.A00 requirement #2 which states, 'inadvertent containers (with internal diameters greater than 5 inches) shall be controlled such that any uranium-bearing liquid that could be collected is geometrically favorable.' Some examples of these violations are:

1. Several drums had deep lids (>1.5") such that solution could accumulate in the lipped area.
2. A tray (>1.5") had no drainage holes.
3. A drain pan (>1.5") had a plugged drainage hole.
4. A section of ventilation duct was bowed inward which could allow solution collection (>1.5").

"This was a loss of one control (volume/geometry) in the double contingency principle for each violation. The second control (physical Integrity of nearby uranium bearing system) was maintained throughout this event.

"One (1) violation was with NCSA-705_076.A00 requirement #3 which states, 'Flexible materials (such as plastic sheeting) shall be configured or secured such that they can not be deformed into an inadvertent container.' A rack contained several bagged items. The bagged items were oriented such that an unsafe volume could accumulate if a leak developed. This is a loss of one control (volume/geometry) in the double contingency principle. The second control (physical integrity of nearby uranium bearing system) was maintained throughout this event.

"Four (4) violations were with NCSA-705_076.A00 requirement #4 which states in part, 'Absorbent materials shall be covered so that they cannot absorb uranium bearing liquids or modified such that any uranium bearing liquid could be collected is geometrically favorable.' Cheese cloth rolls and mop heads were located near areas if a leak developed could absorb solution containing uranium. This was a loss of one control (volume/geometry) in the double contingency principle for each violation. The second control (physical integrity of nearby uranium bearing system) was maintained throughout this event. No uranium bearing material was involved in any of the violations.

"The safety significance of this event is low.

"SAFETY SIGNIFICANCE OF EVENTS:

"All of the identified problems involved the loss of geometry or volume of the inadvertent container. No uranium bearing material was involved in any of the identified problems since the remaining barrier to criticality (the physical integrity of nearby uranium bearing systems) was maintained. Therefore, the safety significance of this event is low.

"POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO[S] OF HOW CRITICALITY COULD OCCUR):

"If a large leak developed in a nearby uranium bearing system, the identified inadvertent containers could have accumulated an unsafe volume/geometry of material.

"CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.);

"The parameters controlled were geometry, volume and the physical integrity of nearby uranium bearing systems.

"ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE OF CRITICAL MASS):

"No uranium bearing material was involved with these problems. The nearby uranium bearing systems had various concentrations.

"NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES:

"The inadvertent containers identified were not configured, oriented, or modified to preclude an unsafe volume/geometry from accumulating.

"CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEM AND WHEN EACH WAS IMPLEMENTED:

"Fissile material operations in the affected area have been suspended pending further investigation and subsequent corrective actions."

The described violations are representative of the items identified. The investigation is ongoing. Operations informed the NRC Resident Inspector and DOE Site Representative.

* * * UPDATE AT 2238 ON 05/02/00 TO PR-PTS-00-A2288 BY KURT SISLER TO JOLLIFFE * * *

On 05/2/00, five additional violations of NCSA-0705_076.A00 requirements were identified while completing the X-705 facility Nuclear Criticality Safety walkdowns. All fissile operations in the X-705 facility are still suspended pending assessment and resolution of discrepancies identified during the walkdowns. All five discrepancies were corrected at the time of initial discovery.

Four violations were with NCSA-0705_076.A00 requirement #2 as stated above. The violations consisted of situations in which equipment or material was oriented such that it could accumulate uranium-bearing solution or liquid in a geometrically unfavorable configuration. This constituted the loss of one control of the double control contingency (geometry/volume). The second control (physical integrity of the nearby uranium bearing systems) was maintained throughout this event.

One of the violations was with NCSA-0705_076.A00 requirement #4 as stated above. A large string mop was discovered to not be controlled as required in the NCSA. This also constituted the loss of one control (geometry/volume) of the double contingency principle. The second control (physical integrity of nearby uranium-bearing systems) was maintained throughout this event.

The NRC Resident Inspector and the Site DOE Representative were notified of this update.

The NRC Operations Officer notified the R3DO Bruce Burgess and NMSS EO Josie Piccone (by fax).

24 HOUR NRC BULLETIN 91-01 REPORT

"At 1458, on 5/1/00, The Plant Shift Superintendent (PSS) was notified that the C-360 building drain configuration was found to deviate from the assumptions of Nuclear Criticality Safety Evaluation (NCSE) 3972-11. The NCSE credits the flow of water cut of the building drains during a fissile material release to be precluded from backing up and washing large quantities of uranium into the elevator and scale pits. Contrary to this assumption, a valve in the drain system closes automatically, as part of the building containment system in response to the release. This allows water supplied to an Instrument cooler to accumulate in the basement and potentially wash uranium into unfavorable geometry pits.

"SAFETY SIGNIFICANCE OF EVENTS:

"The conductivity cell drain system is not configured as credited for double contingency. No release has occurred and the operation has been shutdown to preclude further fissile materiel operations pending resolution of this issue. The design of the drain system as credited for double contingency is in error.

"POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR):

"In order for a criticality to be possible, a large release or multiple small releases, resulting In an unsafe mass of fissile material, would have to occur.

"Additionally upon building containment, this material would have to be washed in sufficient quantity and concentration into an unfavorable geometry pit.

"CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.:

"Double contingency for this scenario is established by implementing mass and geometry controls.

"ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS LIMIT AND % WORST CASE CRITICAL MASS):

"There has been no release of UF6. No licensed material Is present in the unfavorable geometry pits.

"NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES:

"The first leg of double contingency relies on system integrity to ensure that a large release or multiple concurrent small releases of fissile material are unlikely. This control was not violated and the first leg of double contingency was maintained.

"The second leg of double contingency Is based on precluding the transport and accumulation of large quantities of uranium into the 0.360 scale and elevator pits, This control Is Implemented through reliance on the design of the drain system. Credit is taken for the sanitary water draining directly to the elevator pit instead of backing up on the basement floor which prevents large amounts of uranium from washing into the unfavorable geometry pits. Contrary to this assumption sanitary water from the autoclave conductivity cell will overflow tile normal drain lines and flow directly to the basement floor following building containment. Therefore, the condition required to assure safe geometry was not maintained.

"CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED:

"Cylinder sampling and transfer operations in C-360 have been discontinued until deficiencies are corrected."

The NRC resident inspector has been informed of this event.