Paducah - criticality controls not followed during seal exhaust trap media replacement

PADUCAH GASEOUS DIFFUSION PLANT - 04/24/2003

CRITICALITY CONTROL 24-HOUR REPORT (RESPONSE BULLETIN 91-01)

The following information was obtained from the regulatee via facsimile:

"At 1320 [CDT] on 4/23/03, the Plant Shift Superintendent (PSS) was notified that the trap media replacement activities for C-337 #4 Seal Exhaust (SX) trap were performed on 4/6/03 through 4/8/03 and the trap media and the bottom screen were replaced. Contrary to the requirements of NCSA CAS-007, 'independent verification of no trap media below the bottom screen' was not performed prior to the bottom flange being removed. This requirement ensures that an unanalyzed volume of media does not spill from the trap.

"The NRC Resident Inspector has been notified of the event.

"PDGP Assessment and Tracking Report No. ATR 03-1199 PGDP Event Report No. PAD-2003-008 NRC Event Worksheet [39791].

"Responsible Division: Maintenance

"SAFETY SIGNIFICANCE OF EVENTS:

"Although the trap was not independently verified to be essentially empty of accumulated trap mix, prior to in-place maintenance, no media was found when the bottom flange was removed.

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

"In order for a criticality to be possible, a critical volume of trap mix would have to be accumulated in an unsafe geometry.

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

"Double contingency is maintained by implementing two controls on volume.

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

"There was no media found when the bottom flange was removed.

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

"The first leg of double contingency relies on controlling the volume of trap mix available to be spilled from the trap after removal of media above the bottom screen. NCSA CAS-007 requires the trap to be verified emptied of trap media prior to in-place maintenance, thus ensuring that the trap does not contain any accumulated trap mix in excess of a 5.5-gal drum. Verification of the trap mix accumulated in the trap was not done, thus, this control was violated.

"The second leg of double contingency relies on controlling the volume of trap mix available to be spilled from the trap after removal of media above the bottom screen. NCSA CAS-007 requires the trap to be independently verified emptied of trap media prior to in-place maintenance. Independent verification of the trap mix accumulated in the trap was not performed, therefore, this control was violated. Neither of the controls (verification and independent verification) of the single parameter (volume) were performed and double contingency was not maintained.

"No trap media was spilled from the trap, thus maintaining the volume parameter.

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

"None."

Operations notified the NRC resident inspector.

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|Fuel Cycle Facility                              |Event Number:   39791       |
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| FACILITY: PADUCAH GASEOUS DIFFUSION PLANT      |NOTIFICATION DATE: 04/24/2003|
|   RXTYPE: URANIUM ENRICHMENT FACILITY          |NOTIFICATION TIME: 05:42[EDT]|
| COMMENTS: 2 DEMOCRACY CENTER                   |EVENT DATE:        04/24/2003|
|           6903 ROCKLEDGE DRIVE                 |EVENT TIME:             [CDT]|
|           BETHESDA, MD 20817    (301)564-3200  |LAST UPDATE DATE:  04/24/2003|
|    CITY:  PADUCAH                  REGION:  3  +-----------------------------+
|  COUNTY:  McCRACKEN                 STATE:  KY |PERSON          ORGANIZATION |
|LICENSE#:  GDP-1                 AGREEMENT:  Y  |MONTE PHILLIPS       R3      |
|  DOCKET:  0707001                              |DANIEL GILLEN        NMSS    |
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| NRC NOTIFIED BY:  TOM WHITE                    |                             |
|  HQ OPS OFFICER:  HOWIE CROUCH                 |                             |
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|EMERGENCY CLASS:          NON EMERGENCY         |                             |
|10 CFR SECTION:                                 |                             |
|NBNL                     RESPONSE-BULLETIN      |                             |
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