ML20141A441
| ML20141A441 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 06/16/1997 |
| From: | Allen D UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-97-2010, NUDOCS 9706200282 | |
| Download: ML20141A441 (5) | |
Text
United Statis Enrichm:nt Corporation 2 Democracy Center 6903 Rockledge Drive Bethesda. MD 20817 P
Tel. (301) S64 3200 Fax:(301) 564-3201
!! iited Sate 8 f,ririclimellt Corporatiott June 16,1997 GDP-97-2010 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)- Docket No. 70-7002 - Event Report 97-10 Pursuant to Safety Analysis Report (SAR), Section 6.9, Table 6.9-1, J (2), enclosed is the required 30 day written Event Report (ER) for an event involving a UF cylinder high pressure 6
alarm actuation at the Portsmouth Gaseous Diffusion Plant. Investigation activities are continuing with a final report scheduled for August 7,1997. There are no new commitments contained in the report.
Should you require additional information regarding this event, please contact Scott Scholl at (614) 897-2373.
Sincerely, M kb Dale Allen General Manager 1 j Portsmouth Gaseous Diffusion Plant DIA:SScholl:cw Enclosures (2) cc:
NRC Region 111 g{g l]lllll]lll C. Cox/D. Hartland, NRC Resident inspectors, PORTS 9706200282 970616 7
PDR ADOCK 07007002 C
PDR Offices in Paducah. Kentucky Portsmouth. Ohio Washington.DC
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j Dnited States Nuclear Regulatory Commission i
- June 16,1997
- Page Two Distribution Robert L. Woolley -
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J.'Adkins, IlQ J. Anzelmo, PORTS
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R; Boclens, PORTS
' J. Bolling, PO'RTS M. Boren, PGDP S. Brawner, PGDP J, Dietricli, LMUS 1
. L F n, PORTS ik R. Gaston, PORTS.
M. Hasty, PORTS P. IIopkins, PORTS l
J. Labarraque, PGDP, B. Lantz, PORTS R. Lipfert, PORTS R. McDermott, PORTS J. Miller, HQ J. Mize, PGDP J. Morgan, PORTS J. Oppy, PORTS -
G. Price, PORTS -
A. Rebuck-Main, HQ R. Robinson, PORTS S. Routh, HQ -
i S. Scholl, PORTS B. Sykes, PGDP D. Thompson, PORTS 4
D. Towne, PORTS M. Valentine, PORTS R. Wells, HQ.
PORTS Record Management o
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b Docket No. 70-7002' Enclosure Page1of3 Event Report 97 Description of Event i:
On MEy 23,1997, at 0125 hours0.00145 days <br />0.0347 hours <br />2.066799e-4 weeks <br />4.75625e-5 months <br />, X-343 Autoclave (AC) #5 was in Mode II, heating 30 inch -
- (2.5-ton) Russian Uranium llexafluoride (UF,) cylinder #LUO705 when the audible alaim for UF. cylinder high pressure autoclave steam shutoff was received. Operators responding to the alarm observed that the internal cylinder pressure was 115 psia, which was also the afarm i
setpoint. Steam supply valve FV-513 was verified closed as designed. Five. minutes later at 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br />, while in Mode VII and with the steam supply valve still closed, AC #5 alarmed a.
second time when the cylinder pressure reached 130 psia. The actuation of the UF cylinder high pressure autoclave steam shutoffis reportable in accordance with the Safety Analysis Report
- (SAR), Table 6.9-1, J (2).
l At 0105 hours0.00122 days <br />0.0292 hours <br />1.736111e-4 weeks <br />3.99525e-5 months <br />, at the start of the cylinder heating process the cylinder cold pressure reading was 6.0 psia. At 0124 hours0.00144 days <br />0.0344 hours <br />2.050265e-4 weeks <br />4.7182e-5 months <br />, during the heating process the operator observed the cylinder pressure at 45.0 psia, which was higher than what is normally expected after 19 minutes of heating.~ In i
accordance with procedure XP4-TE-FD2701, "X-343 and X-342 Autoclave Operation," the operator prepared to hot burp (vent to the cascade) enough UF to reduce cylinder pressure. One minute later, at 0125 hours0.00145 days <br />0.0347 hours <br />2.066799e-4 weeks <br />4.75625e-5 months <br />, before the operator could hot burp the cylinder the autoclave alarmed i
at 115 psia due to cylinder high pressure.- The operator responded according to procedure and immediately hot burped the cylinder. The cylinder pressure following the hot burp was 9.0 psia.
l At 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br />, although the steam supply was isolated from the autoclave, the operator noticed the cylinder pressure had increased to 70 psia and rising. While the operator was proceeding to hot burp the cylinder for the second time the autoclave alarmed again due to high cylinder pressure. The operator responded and immediately hot burped the cylinder. After the second hot burp the cylinder pressure stabilized at 20.0 psia. The highest pressure observed during this event was 130 psia which is less than the 214.4 psia maximum allowable working pressure (MAWP) of 2.5-ton cylinders.
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The UF cylinder high pressure autoclave steam shutoff system is provided to prevent internal 6
cylinder over pressurization caused by the normal heating of a UF cylinder containing excessive 6
amounts of" light" gases. In addition, in the event an over filled cylinder is heated in an autoclave the UF cylinder high pressure autoclave steam shutoff system prevents the internal i
cylinder pressure from exceeding the hydrostatic test pressure of the cylinder.
Cause of Event l
The direct cause of th$ UFi cylinder high pressure alarm is under investigation but is likely
' caused by " light" gases trapped within the solid or the unequal distribution of UF behind the 6
cylinder valve.
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Docket No. 70-7002 Enclosure Page 2 of 3 Event Report 97-10 Similar pressure alarms in the past have occurred while heating Russian 2.5-ton cylinders. Two such events occurred on September 9,1995 and one event occurred on October 24,1996. The pressure increases are similar to previous pressure increases experienced at PORTS and PGDP when heating 14-ton Tails cylinders withdrawn during cold weather. It is believed that rapid cooling causes UF. to deposit near the valve, separating it from the larger cylinder void volume.
Other factors that could have produced the same type of pressure increase were eliminated by weight data and the enalysis oflaboratory samples taken following the event. Weight data showed that the cylinder was filled to 4994 pounds, which was below the 5020 pound maximum cylinder fill limit. The laboratory samples taken following hot burping the cylinder indicated no excessive " light" gases were present in the cylinder.
i Corrective actions resulting from these previous events included revising operation procedures to give the operator the authority to hot burp a cylinder when cylinder pressure is rising rapidly or has exceeded 90 psia. However, in this event the pressure rise occurred more rapidly than expected, preventing the operator from relieving the cylinder pressure before the 115 psia set point was exceeded.
On May 23,1997, Customer Services and Product Scheduling put a hold on heating 2.5-ton Russian cylinders until an engineering evaluation can be completed to determine corrective actions to prevent a recurrence of this event. On May 29,1997 the cylinder hold was modified to allow heating of the Russian cylinders that have previously been through a heating cycle at PORTS. This action was taken because it is believed that the pressure increases occurring during initial heat cycle are the result of the cylinder cooling process used at Russian facilities.
An engineering evaluation is underway to determine corrective actions to prevent a recurrence of this event. A hold has been placed on Russian 2.5-ton cylinders that have not been previously 1
heated at PORTS. These cylinders will not be heated until corrective actions to prevent a recurrence of this event are implemented.
Corrective Actions Corrective actions will be provided with the final event report.
Extent of Exposure ofIndividuals to Radiation or Radioactive Materials There were no exposures to individuals from this incident to radiation or radioactive materials.
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Docket No. 70-7002
' Enclosure Page 3 of 3 Event Report 97-10 Lessons Learned Lessons learned will be provided with the final event report.
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