ML20197G880
| ML20197G880 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 12/07/1998 |
| From: | Jonathan Brown UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-98-2049, NUDOCS 9812110064 | |
| Download: ML20197G880 (4) | |
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J r USEC A Global Energy Company December 7,1998 GDP 98-2049
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United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 Event Report 98-14 Pursuant to the Safety Analysis Report Section 6.9, Table 6.9-1, J(2), Enclosure 1 provides the required 30 day Event Report for an event that resulted from the actuation of a Cascade Automatic Data Processing (CADP) smokehead in the X-330 Tails Area at the Portsmouth Gaseous Diffusion Plant due to an unplanned telease of UF. Enclosure 2 is a list of commitments contained in the 6
report.
Should you require additional information regarding this event, please contact Scott Scholl at (740) 897-2373.
Sincerely, i
. Morris Brown
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General Manager Portsmouth Gaseous Diffusion Plant
Enclosures:
As Stated i
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NRC Region III Office NRC Resident Inspector - PORTS 6
9812110064 991207 9~
PDR ADOCK 07007002 1
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P.O. Ilox 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
GDP 98-2049 Page 1 of 2 Event Report 98-14 Description of Event At 2316 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.81238e-4 months <br /> on November 6,1998, while bringing Tails compressor 30WB1 up to condensing pressure, two smokeheads in the X-330 Process Building Tails Withdrawal 30WB1 Compressor Area alarmed. At 2318 hours0.0268 days <br />0.644 hours <br />0.00383 weeks <br />8.81999e-4 months <br /> an operator responded to Tails to investigate, wearing proper personnel protective equipment (PPE). No smoke or odors were observed. Concurrently, the 30WB1 compressor and piping were vented below atmospheric pressure by 2320 hours0.0269 days <br />0.644 hours <br />0.00384 weeks <br />8.8276e-4 months <br />, preventing any further outgassing.
Just prior to this event, the 30WB1 compressor had been out of senice to perform maintenance on its oil lines. Following maintenance, a compressor leak rate test was performed and passed prior to restart. On November 6,1998, at 0827 hours0.00957 days <br />0.23 hours <br />0.00137 weeks <br />3.146735e-4 months <br />, Compressor 30WB1 was started. At 2310 hours0.0267 days <br />0.642 hours <br />0.00382 weeks <br />8.78955e-4 months <br />, the compressor suction valve was opened and, at 2313 hours0.0268 days <br />0.643 hours <br />0.00382 weeks <br />8.800965e-4 months <br />, the condenser pressure was above atmospheric. At 2316 hours0.0268 days <br />0.643 hours <br />0.00383 weeks <br />8.81238e-4 months <br />, the smoke detectors alarmed.
Following the event on November 6,1998, Health Physics surveyed the equipment and found no evidence of an outgassing. On November 8,1998, Maintenance performed a soap bubble leak test and discovered a small crack in a copper to monel brazed joint on the WWB-27 discharge valve buffer supply line. The operating pressure at the discharge valve is approximately twice atmospheric to condense the UF gas to a liquid.
6 The outgassing resulted in the actuation of Cascade Automatic Data Processing (CADP) smokehead SSWL and the Tails Pyrotronic alarm. The actuation of the CADP smoke detector on a system operating above atmospheric pressure is reportable in accordance with the Safety Analysis Report, Section 6.9, Table 6.9-1, J(2).
The material that outgassed was low-enriched UF. at approximately 0.3% U-235.
Cause of Event The direct cause of the CADP actuation was a UF release from the copper to monel brazed joint on 6
the WWB-27 discharge valve buffer supply line.
The root cause of the outgassing was damage to the WWB-27 discharge valve equalizing line, which is believed to have occurred during maintenance work. The 30WB1 compressor had been out of senice while Maintenance worked inside the compressor housing. The Tails housing is very small to conserve heat and prevent freezcouts. There are numerous instrument lines contained in the housing and workers must wear PPE while working inside. This creates cramped conditions which
GDP 98-2049 Page 2 of 2 Event Report 98-14 may increase the potential for accidental damage during operations and maintenance activities.
The WWB-27 discharge valve buffer line comes off the WWB-27 valve at floor level near the housing entrance, which makes it vulnerable to inadvertent damage from personnel and equipment l
entering to work on any of the equipment in the housing as well as those doing maintenance on the 30WB1 compressor. It is believed that during the maintenance work that this line was bumped causing a small crack in the brazed joint. The equipment had been leak checked prior to restarting j
the compressor, however the leak was too small to be detected by the leak rate test.
A review of previous similar eWnts found that a previous outgassing occurred involving the WWB-27 discharge valve inside the Tails compressor housing. On March 20,1997, CADP smokehead SSWL and the Tails Pyrotronics alarmed. The outgassing occurred at the WWB-27 J
discharge valve bellows due to a low buffer pressure condition. A corrective action for this event required installation of a new variable pressure buffer system to maintain a buffer pressure above the process pressure. The installation was completed and the variable buffer system is in operation.
Because of damage to the buffer line, on November 6,1998, the variable buffer was not able to i
prevent another outgassing.
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Corrective Actions By January 10,1999, issue a Lessons Leamed to Maintenance personnel emphasizing the importance associated with bending / breaking small lines within housings.
j Extent of Exposure ofIndividuals to Radiation or Radioactive Materials There were no exposures to individuals from this incident to radiation or radioactive materials.
I Lessons Learned i
i Instrument lines are vulnerable to damage during maintenance work. When working in areas where instrument lines are located, personnel must be particularly careful to avoid contact with these instrument lines. This is especially true in areas such as the inside of the Tails housing where crowded conditions exist.
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l GDP 98-2049 Page1 of1 l
Event Report 98-14 List of Commitments By_ January 10, 1999, issue a Lessons Learned to maintenance personnel emphasizing the importance associated with bending / breaking small lines within housings.
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