United States Nuclear Regulatory Commission - Protecting People and the Environment
Home > NRC Library > Document Collections > Reports Associated With Events > Event Notification Reports > 1999

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  

+------------------------------------------------------------------------------+
|Fuel Cycle Facility                              |Event Number:   35361       |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| 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      |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
+------------------------------------------------------------------------------+

                                   EVENT TEXT                                   
+------------------------------------------------------------------------------+
| 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.  |
+------------------------------------------------------------------------------+

+------------------------------------------------------------------------------+
|Power Reactor                                    |Event Number:   35362       |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| 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       |                             |
|                                                |                             |
|                                                |                             |
|                                                |                             |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|UNIT |SCRAM CODE|RX CRIT|INIT PWR|   INIT RX MODE  |CURR PWR|  CURR RX MODE   |
+-----+----------+-------+--------+-----------------+--------+-----------------+
|1     N          Y       100      Power Operation  |100      Power Operation  |
|                                                   |                          |
|                                                   |                          |
+------------------------------------------------------------------------------+
                                   EVENT TEXT                                   
+------------------------------------------------------------------------------+
| - 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.                            |
+------------------------------------------------------------------------------+

+------------------------------------------------------------------------------+
|Power Reactor                                    |Event Number:   35363       |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
| 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  |
+------------------------------------------------------------------------------+
                                   EVENT TEXT                                   
+------------------------------------------------------------------------------+
| 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.       |
+------------------------------------------------------------------------------+