ML20216F068
| ML20216F068 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 03/12/1998 |
| From: | Morgan J UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-98-2013, NUDOCS 9803180242 | |
| Download: ML20216F068 (5) | |
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!r USEC A Global Energy Company March 12,1998
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GDP 98-2013 i
Ur.ited States Nuclear Regulatory Con: mission Attention: Document Control Desk j
Washington, D.C. 20555-0001 Portsmauth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 l
Event Report 98-03
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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 Diffusion Nant. Enclosure 2 is a list of commitments made in the report.
Should you require additional information regarding this event, please contact Scott Scholl at (740) 897-2373.
Sincerely, I
im Morgar Acting General Manager Portsmouth Gaseous Diffusion Plant l
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Enclosures:
As Stated cc:
NRC Region III Office
.f9 NRC Rr sident Inspector-PORTS
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9803180242 980312 PDR ADOCK 07007002:.
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IkEh55,Ill5llllll\\ll P.O. Box 800, Portsmouth, OH 45661 Telephone 614-897-2255 Fax 614-897-2644 hr:p:/hvww.usec.com Offices in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC
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GDP 98-2013 Page1of3 Event Report 98-03 Description of Event On February 11,1998, at 1643 hours0.019 days <br />0.456 hours <br />0.00272 weeks <br />6.251615e-4 months <br />, the Ccscade Automatic Data Prmessing (CADP) smoke detector S64, which monitors cell 31-2-6 alarrned in the X-330 Process Building Area Control Room
- 2. Following tw alarm at approximately 1646 hours0.0191 days <br />0.457 hours <br />0.00272 weeks <br />6.26303e-4 months <br />, operations personnel investigating the alarm observed UF smoke above the cell housing where the smoke detector head was located. Operations 6
personnel in the area followed the "See & Flee" policy and evacuated the affected area.
Building " recall" was sounded at 1646 hours0.0191 days <br />0.457 hours <br />0.00272 weeks <br />6.26303e-4 months <br /> and the Fire Department and Plant Shitt Superintendent
. (PSS) were notified.. At 107 hours0.00124 days <br />0.0297 hours <br />1.76918e-4 weeks <br />4.07135e-5 months <br />, cell 31-2-6 motors were stopped which reduced the cell pressure to below atmosphere. Due to a valve sequence timer malfunction, the required valves did not travel and isolate the cell from the cascade. As a result, the cell pressure rose to slightly above atmospheric pressure (approximately 15 psia). At 1650 hours0.0191 days <br />0.458 hours <br />0.00273 weeks <br />6.27825e-4 months <br />, the PSS responded to the X-330 Process Building. At 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br />, the PSS gave permission for an operator wearing a respirator to go to the 31-2-6 Lccal Control Console (LCC) and operate the required valves using alternate means.
The operator took the cell off stream by operating the valves using the manual switches at the LCC.
At 1708 hours0.0198 days <br />0.474 hours <br />0.00282 weeks <br />6.49894e-4 months <br />, the cell pressure was reduced to below atmosph:re (approximately 13.75 psia). At 1733 hours0.0201 days <br />0.481 hours <br />0.00287 weeks <br />6.594065e-4 months <br />, personnel using self-contained breathing apparatus and dressed in appropriate personal
_ protective equipment (PPE) entered the cell floor. The area was sampled for airborne radioactivity and all samples were below detection levels. An all clear was given by the PSS at 1834 hours0.0212 days <br />0.509 hours <br />0.00303 weeks <br />6.97837e-4 months <br />.
Operators also noted the buffer system did not alarm prior to or in nediately following the UF6 release.
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 Q safety systems when moNring equipment operating above atmospheric pressure. In this instance, the monitored equip ment (cell 31-2-6) 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 due to an out-leakage of UF. at a broken copper tubing buffer line. The buffer line is connected to a pressurized double wall bellows expansionjoint on the compressor discharge line between stage -> comprwor and stage 9 converter. The area between the inner and outer bellows is pressurized with dry air to approximately 25 psia to prevent an out-leakage while the cell is running above atmospheric pressure. The broken buffer line in combination with a leaking internal bellows in one of the expansionjoints connected to the bufTer system provided a path for the UF to leak to atmosphere.
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i GDP 98-2013 Page 2 0f 3 j
Event Report 98-03 The root cause of the expansion joint, copper tube buffer line leak and buffer alarm failure has not yet been determined. An analysis of 6e failed components cannot be performed until they are removed from the cell. An engineering evaluation of the failed expansionjoint, buffer line and the 3
cause for the buffer alarm failure is planned following removal of these components. The cell will i
remain out of service until the exfansion joint and buffer line are replaced ana me cause for the l
buffer alarm failure is determined rud corrected The Safety Analysis Report (SAR) Section 4.1.1.3.1, discusses the occurrence of small UF leaks originating from ruptured copper tubing and through buffer systems. The SAR states "Small amounts of UF und other toxic materials such as HF, CLF and UO F can be released during 6
3 2 2 sampling operations, seal changes, failure to obtain cufficient cell and piping UF negatives, ruptured 6
copper tubing, and possibly through buffer systems. These releases are prevented primarily by using engineering and administrative controls. To protect the operator in the ynlikely event a release does occur, operating specifications require that personnel performing opdrations and maintenance, where the possibility of release exist, wear protective equipment such as an individually fitted gas mask.
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Releases in these cases may mean that a few grams of UF will escape to the atmosphere. Tnere are 6
no TSR systems (Safety Systems) to prevent the release of UF while performing these types of 6
operatWns. Engineering and administrative controls are considered adequate."
The double walled expansion joints are buffered to reduce the probability that an expansion joint leak will result in a UF release to atmosphere. The buffer system design includes an alami that will 6
alert operators if there is a significant change in buffer system pressure or flow. These design features provide engineering controls to help prevent minor releases of UF. In this event, the buffer 6
system did not perform as designed because it did not alarm when a leak occurred in the expansion joint and buffer tubing.
Corrective Actions 1.
By May 18,1998, Engineering will perform an evaluation to determine the cause for the buffer system failure to alarm. Based on the result of the evaluation, appropriate corrective actions will be determined.
4 Extent of Exposure ofIndividuals <.> Radiation or Radioactive Materials Nine individuals were required to submit a urine sample as a rc. ult of the out-leakage. Eight individuals resuhs were below 5 ug/ liter for soluble uranium (flag level) and one individual was above flag level with 120 ug/ liter for soluble uranium. The estimated intake for the eight individuals was below 25 ug of soluble uranium. The intake for the one individual was 122ug of soluble uranium. Exposures to individuals from this event were well below plant administrative and regulatory limits.
GDP 98-2013 Page 3 of 3 Event Report 98-03
. Lessong Learned Operators responded to this event in accordance with plant policies and procedures. Evaluation of the failed components associated with this event is ongoing.
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GDP 98-2013
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Page of I of1 Event Report 98-03 List of Commitments 1.
By May 18,1998, Engineering will perform an evaluation to determine the cause for the buffer system failure to alarm. Based on the result of the evaluation, approprie.e corrective actions will be determined.
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