ML20248B969
| ML20248B969 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 05/27/1998 |
| From: | Jonathan Brown UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-98-2021, NUDOCS 9806020031 | |
| Download: ML20248B969 (5) | |
Text
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USEC l
. A Global Energy Company 1
May 27,1998
. GDP 98-2021 i
United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 l
Event Report 98-06 Pursuant to Safety Analysis Report (SAR), Section 6.9, Table 6.9-1, J (2), Enclosure 1 provides the required 30 day written Event Report for an event involving an actuation of the Cascade Automatic Data Processing (CADP) Smoke Detection System in the X-330 Building at the Portsmouth Gaseous l
Diffusion Plant. Investigation activities are continuing to determine the root cause and corrective actions for this event. This report will be revised following completion of these activities. The revised report is scheduled for December 20,1998. Enclosure 2 is a list of commitments made in the report.
Should you require additional information regarding this event, please contact Scott Scholl at (614) 897-2373.
Sincerely, M
h J Morris Brown General Manager Portsmouth Gaseous Diffusion Plant
Enclosures:
As Stated cc:
NRC Region III Office I
NRC Resident inspector - PORTS
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9806020031 990527 l
PDR ADOCK 07007002; C
PDR i
PO. Box 800, Portsmouth, OH 45661 Telephone 614-897-2255 Fax 614-897-2644 http://www.usec.com Offices in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC l
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'O GDP 98-2021 Page 1 of 3 Event Report 98-06 Description of Event On April 24,1998, at 1807 hours0.0209 days <br />0.502 hours <br />0.00299 weeks <br />6.875635e-4 months <br />, while in withdrawal mode III, the Cascade Automatic Data Processing (CADP) smoke detectors SSWA and SSWE that monitor the Tails withdrawal area, alarmed in the X-330 Process Building Area Control Room #2. The control room operator silenced the alarm and informed the First Line Manager (FLM). After observing the outleakage message and
- the location code of the smoke detector heads printed on the alarm typer, an operator was dispatched to investigate the smoke detectors' coverage area. The operator did not detect a UF outleakage or 6
other conditions that could have actuated the detectors. Since no smoke was detected, the alarm actuations were handled as spurious actuations in accordance with procedure XP4-CO-CA2245,
" Smoke Detection Portion of the CADP System." Smoke alarm SSWA cleared at 1810 hours0.0209 days <br />0.503 hours <br />0.00299 weeks <br />6.88705e-4 months <br /> and SSWE cleared at 1813 hours0.021 days <br />0.504 hours <br />0.003 weeks <br />6.898465e-4 months <br />. On April 26,1998, at 1222 hours0.0141 days <br />0.339 hours <br />0.00202 weeks <br />4.64971e-4 months <br />, while in withdrawal mode III,
' CADP smoke detector SSWE alarmed for the second time. Operations personnel again responded
- in accordance with procedure XP4-CO-CA2245. The operator did not detect UF outleakage. This 6
alarm actuation was also handled as a spurious actuation. The alarm cleared at 1225 hours0.0142 days <br />0.34 hours <br />0.00203 weeks <br />4.661125e-4 months <br />.
On April 27,1998, at 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br />, the area inside the enclosed pipe galley was inspected to determine if there was evidence of a UF release. During the inspection a small amount of hydrolyzed UE 6
(UO F ) contamination was observed on the outside surface of block valve SMDB-2, an isolation 2 2 valve at withdrawal position #2. It was determined that the valve was the likely cause of the CADP actuations previously believed to be spurious. On April 27,1998, at 1036 hours0.012 days <br />0.288 hours <br />0.00171 weeks <br />3.94198e-4 months <br />, the PSS declared Tails withdrawal position #2 inoperable.
The outgassing was similar to the types ofleaks described in the SAR (Section 4.1.?.3.1) which states, "Small amounts of UF and other toxic materials such a liF, CIF and UO F can be released 6
3 2 2 during sampling operations, seal changes, failure to obtain sufficient cell and piping UF negatives, 6
ruptured copper tubing and possibly through buffer systems. These releases are prevented primarily by using engineering and administrative controls. To protect the operator in the unlikely event a release does occur, operation specifications require that personnel performing operations and 4
maintenance, where.the possibility of release exist, wear protective equipment such as an individually fitted gas mask. Releases in these cases may mean that few grams of UF will escape 6
..to the atmosphere. There are no system (Safety Systems) to prevent the release of UF while 6
performing these types of operations. Engineering and administrative controls are considered l
adequate."
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. Valve SMDB-2 and the two CADP smoke detectors that alarmed are located inside an enclosed pipe galley. During the outgassing personnel were not exposed to UF smoke. During the valve 6
outgassing the smoke discharged from the valve was contained within the enclo;.ed pipe galleys and
- the' airborne alpha detector located outside the enclosed pipe galley did not alarm.
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GDP 98-2021 Page 2 0f 3 l;
Event Report 98-06 The valve designated as SMDB-2 is a 1-inch, screwed bonnet, metal to metal seat, globe valve. The valve is an "S" type manually operated valve, manufactured by the Crane Company. These valves are used throughout the cascade on feed, withdrawal, exhaust and auxiliary systems. Since l
replacement valves and subassemblies have not been available from the manufacturer for 40 years, plant personnel have routinely rebuilt, inspected and installed replacement subassemblies in the "S" type valves. Approximately 20 subassemblies are rebuilt and installed each year. A review of problem reports for the past two years found no evidence of UF outgassings from "S" type valves.
6 According to the Safety Analysis Report (SAR) for the Portsmouth Gaseous Diffusion Plant, the CADP smoke detectors are part of the UF detection alarm system and are classified as a Q safety l
6 system when monitoring equipment operating above atmospheric pressure. In this instance, the
- monitored equipment was operating above atmospheric pressure. This CADP smoke detector actuation is reportable in accordance_with SAR, Section 6.9 Table 6.9-1, J (2).
Cause of Event The direct cause for the CADP UF Smoke Detection System actuation was an outgassing of UF.
from valve SMDB-2. While in withdrawal mode the valve is maintained in the "open" position. The valve is turned to the " closed" position when the system is isolated for service / repair.
On March 31,-1998, approximately one month before the outgassing, maintenance personnel mplaced the valve subassembly in valve SMDB-2. The replacement subassembly was rebuilt and
-QC inspected in the X.-720 Valve Shop. On April 1,1998, following installation of the valve subassembly, Cascade Operations verified the valve was not leaking.
q The root cause of the valve outgassing and the CADP alarm actuation has not yet been determined.
An analysis of the failed component cannot be performed until the valve subassembly is removed from the system. An engineering evaluation of the failed valve assembly is planned following removal of the valve. Tails withdrawal position #2 will remain out of service until the subassembly l is replaced.
Corrective Actions j
a 1.
By September 30,1998, Cascade Operations will ensure the valve subassembly is removed i
from the valve.
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By October 30, 1998, Engineering will perform an inspection of the failed valve l
F
. subassembly.
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GDP 98-2021 Page 3 of 3 Event Report 98-06 3.
By November 20,1998, based on the results of the valve inspection, Engineering will determine appropriate corrective actions.
Extent of Exposure ofIndividuals to Radiation or Radioactive Materials There were no exposures to individuals from this incident to radiation or radioactive materials.
Lessons Learned from the Event Operators responded to this event in accordance with plant policies and procedures. No outgassing was observed. The release was small and could only be detected by observation of hydrolyzed UF6 on the surface of the block valve.
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GDP 98-2021 Page1of1 Event Report 98-06 i
List of Commitments 1.
By September 30,1998, Cascade Operations will ensure the valve subassembly is removed from the valve.
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By October 30, 1998, Engineering will perform an inspection of the failed valve j'
subassembly.
3.
'By November 20,1998, based on the result of the valve inspection, Engineering will determine appropriate corrective actions.
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