Event Notification Report for February 11, 1999
U.S. Nuclear Regulatory Commission
Operations Center
Event Reports For
02/10/1999 - 02/11/1999
** EVENT NUMBERS **
35361 35362 35363
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|Fuel Cycle Facility |Event Number: 35361 |
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| FACILITY: PORTSMOUTH GASEOUS DIFFUSION PLANT |NOTIFICATION DATE: 02/10/1999|
| RXTYPE: URANIUM ENRICHMENT FACILITY |NOTIFICATION TIME: 11:19[EST]|
| COMMENTS: 2 DEMOCRACY CENTER |EVENT DATE: 02/10/1999|
| 6903 ROCKLEDGE DRIVE |EVENT TIME: 07:00[EST]|
| BETHESDA, MD 20817 (301)564-3200 |LAST UPDATE DATE: 02/10/1999|
| CITY: PIKETON REGION: 3 +-----------------------------+
| COUNTY: PIKE STATE: OH |PERSON ORGANIZATION |
|LICENSE#: GDP-2 AGREEMENT: N |GARY SHEAR R3 |
| DOCKET: 0707002 |SCOTT MOORE NMSS |
+------------------------------------------------+FRANK CONGEL IRO |
| NRC NOTIFIED BY: ERIC SPAETH |BOB PIERSON NMSS |
| HQ OPS OFFICER: JOHN MacKINNON | |
+------------------------------------------------+ |
|EMERGENCY CLASS: N/A | |
|10 CFR SECTION: | |
|NBNL RESPONSE-BULLETIN | |
| | |
| | |
| | |
| | |
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EVENT TEXT
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| NRC BULLETIN 91-01, 4-HOUR NOTIFICATION INVOLVING INCORRECT RAFFINATE MASS |
| AND CONCENTRATION CALCULATION |
| |
| On February 10, 1999, X-705 building personnel discovered that a Nuclear |
| Criticality Safety Approval (NCSA) requirement had not been maintained in |
| the X-705 Decontamination Facility. Uranium recovery waste stream solutions |
| are sampled to determine the U-235 concentration, mass, and enrichment as |
| spelled out in NCSA-0705_027, Heavy Metals Precipitation. These sample |
| results are used to calculate U-235 concentration and U-235 mass prior to |
| transferring and processing the waste solutions as identified in the |
| administrative requirements of the NCSA. |
| |
| Sample results for raffinate solutions (recovery waste streams) were |
| recorded incorrectly on the raffinate transfer sheet and the heavy metals |
| batch sheets. The double contingency principle was violated as result of: 1) |
| failure of the operator to correctly determine the U-235 concentration prior |
| to transfer (control "A") and 2) failure of supervision to find the error |
| while verifying the data and calculations (control "B"). This error resulted |
| in solution being transferred and processed to a geometrically unfavorable |
| sludge collection tub without the correct U-235 concentration and U-235 mass |
| being recorded. |
| |
| There was no loss of hazardous/radioactive material or radioactive |
| radiological contamination exposure as a result of this event. |
| |
| SAFETY SIGNIFICANCE OF EVENTS: The safety significance of this event is low. |
| This is because when this material was sampled for enrichment, the |
| enrichment was found to be 3.95% U-235. Also, due to the reduction of HEU |
| material on site, material now being processed through the heavy metals |
| systems routinely has an enrichment less than 10% U-235. |
| |
| POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO[S] OF HOW |
| CRITICALITY COULD OCCUR): For a criticality to occur, both calculations of |
| how much material is in the system must be wrong and the total mass of |
| material must exceed 760 grams U-235. The minimum critical mass for 100% |
| enriched material is approximately 760 grams U-235. Even if the enrichment |
| had been 100%, the total mass in the system as a result of this event would |
| have been 245 grams. |
| |
| Also a second path would be the processing material and collecting material |
| with greater than the minimum critical mass in the heavy metals collection |
| drums. |
| |
| CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY. CONCENTRATION, ETC.): The |
| controlled parameter in this case was mass. (Both of the mass controls were |
| lost because the calculations were in error.) |
| |
| ESTIMATED AMOUNT, ENRICHMENT, FORM OF LICENSED MATERIAL (INCLUDE PROCESS |
| LIMIT AND % WORST CASE OF CRITICAL MASS): The total amount of material in |
| the system was 245 grams U-235 assuming an enrichment of 100%. The |
| enrichment was measured after the event and found to be 3.95% U-235. The |
| material was uranium solution. The minimum critical mass at 100% enrichment |
| is approximately 760 grams U-235, and using the 100% enriched values, the |
| percent worst case critical mass is 32.2%. |
| |
| NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION |
| OF THE FAILURES OR DEFICIENCIES: NCSA-0705_027 requires that material to be |
| processed through the heavy metals recovery system is sampled and the total |
| amount of uranium in the material calculated and recorded by an operator on |
| a transfer sheet and verified by another operator or supervisor on the same |
| sheet. If the enrichment of the sample is not known, an enrichment of 100% |
| is assumed for the calculation. The total amount of U-235 allowed to be |
| processed at any time is limited to 200 grams. The calculations done by both |
| the operator and the verifier used a concentration value ten times less than |
| the actual enrichment, which was only 3.95%. |
| |
| CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEM AND WHEN EACH WAS IMPLEMENTED: |
| The heavy metals precipitation was shutdown and isolated. Similar operations |
| (microfiltration filter press and oil and grease removal unit ) were also |
| shut down and isolated. An investigation has been initiated to determine if |
| similar anomalous conditions exists in those operations. |
| |
| The NRC resident inspector has been informed of this event by the licensee. |
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|Power Reactor |Event Number: 35362 |
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| FACILITY: VOGTLE REGION: 2 |NOTIFICATION DATE: 02/10/1999|
| UNIT: [1] [] [] STATE: GA |NOTIFICATION TIME: 21:59[EST]|
| RXTYPE: [1] W-4-LP,[2] W-4-LP |EVENT DATE: 02/10/1999|
+------------------------------------------------+EVENT TIME: 20:30[EST]|
| NRC NOTIFIED BY: W. R. DUNN |LAST UPDATE DATE: 02/10/1999|
| HQ OPS OFFICER: DICK JOLLIFFE +-----------------------------+
+------------------------------------------------+PERSON ORGANIZATION |
|EMERGENCY CLASS: N/A |THOMAS DECKER R2 |
|10 CFR SECTION: | |
|HFIT 26.73 FITNESS FOR DUTY | |
| | |
| | |
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+-----+----------+-------+--------+-----------------+--------+-----------------+
|UNIT |SCRAM CODE|RX CRIT|INIT PWR| INIT RX MODE |CURR PWR| CURR RX MODE |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|1 N Y 100 Power Operation |100 Power Operation |
| | |
| | |
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EVENT TEXT
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| - FITNESS-FOR-DUTY REPORT - |
| |
| A LICENSED OPERATOR WAS DETERMINED TO BE UNDER THE INFLUENCE OF ALCOHOL |
| DURING A RANDOM FITNESS FOR DUTY TEST. THE EMPLOYEE'S ACCESS AUTHORIZATION |
| TO THE PLANT HAS BEEN DEACTIVATED. REFER TO THE HOO LOG FOR ADDITIONAL |
| DETAILS. |
| |
| THE LICENSEE INFORMED THE NRC RESIDENT INSPECTOR. |
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|Power Reactor |Event Number: 35363 |
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| FACILITY: SAN ONOFRE REGION: 4 |NOTIFICATION DATE: 02/11/1999|
| UNIT: [] [2] [3] STATE: CA |NOTIFICATION TIME: 04:48[EST]|
| RXTYPE: [1] W-3-LP,[2] CE,[3] CE |EVENT DATE: 02/10/1999|
+------------------------------------------------+EVENT TIME: 11:37[PST]|
| NRC NOTIFIED BY: CLAY WILLIAMS |LAST UPDATE DATE: 02/11/1999|
| HQ OPS OFFICER: JOHN MacKINNON +-----------------------------+
+------------------------------------------------+PERSON ORGANIZATION |
|EMERGENCY CLASS: N/A |JOHN PELLET R4 |
|10 CFR SECTION: | |
|AIND 50.72(b)(2)(iii)(D) ACCIDENT MITIGATION | |
| | |
| | |
| | |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|UNIT |SCRAM CODE|RX CRIT|INIT PWR| INIT RX MODE |CURR PWR| CURR RX MODE |
+-----+----------+-------+--------+-----------------+--------+-----------------+
| | |
|2 N N 0 Refueling |0 Refueling |
|3 N Y 100 Power Operation |100 Power Operation |
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EVENT TEXT
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| During a postulated seismic event, Component Cooling Water (CCW) isolation |
| valves which separate the CCW critical loops from the non-critical loop may |
| not operate. |
| |
| "At 1137 PST on February 10, 1999, with Unit 2 in a refueling outage and |
| Unit 3 at about 100 percent power, SCE concluded that isolation valves which |
| separate CCW critical loops [loops to safety-related equipment] from the |
| non-Critical Loop (NCL) may not have operated during a postulated seismic |
| event. |
| |
| "The CCW system is required to perform its intended safety function during a |
| seismic event concurrent with a Loss of Coolant Accident . These valves |
| (28-inch Fisher Type-9241 air/nitrogen-operated butterfly valves) close on a |
| CCW surge tank low-low level alarm or when a Containment Isolation Actuation |
| Signal (CIAS) is received. These isolation valves are normally actuated with |
| non-seismically qualified instrument air and normal nitrogen. During a |
| postulated seismic event, the air and nitrogen systems are assumed to fail. |
| A seismically qualified accumulator tank provides the motive force to close |
| the isolation valves during such events. This actuation occurs through the |
| pressurization and venting of pneumatic tubing. |
| |
| "During outage testing [first time the test has been performed this way] of |
| the Train A CCW isolation valves, the valves would not stroke closed within |
| the required time when actuated by the accumulators only. SCE's Air |
| Operated Valve diagnostic testing determined the pneumatic tube sizing |
| provided insufficient venting to properly actuate the valves, which cause |
| the isolation valves to stroke slower than desired. When the isolation |
| valves between one CCW critical loop and the non-critical loop are opened, |
| SCE now considers that CCW critical loop to be inoperable. |
| |
| "During past plant operation, it is possible that one CCW critical loop was |
| out of service while the remaining critical loop was not isolated from the |
| non-critical loop. If a seismic event were to have occurred in this |
| configuration, it is possible the plant would not have had an operable train |
| of CCW. Consequently, SCE is reporting this occurrence in accordance with |
| 10CFR50.72(b)(2)(iii)(D). |
| |
| "Currently , Unit 2 is in Mode 6 in a refueling outage; there is no safety |
| function requiring the valves to close in this mode. At Unit 3, both CCW |
| trains are functional with the isolation valves for one train closed. In |
| this configuration, Unit 3 is in a 72-hour action statement. SCE plans to |
| modify the valve actuator design within 72 hours to correct this |
| condition." |
| |
| The licensee said that the isolation valves mentioned above should normally |
| close within 10 to 15 seconds. During testing of the valve, the licensee |
| believed that it took approximately 47 seconds for the valves to close. |
| |
| The NRC resident inspector was notified of this event by the licensee. |
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Page Last Reviewed/Updated Thursday, March 25, 2021
Page Last Reviewed/Updated Thursday, March 25, 2021