ENS 44158

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v t e ENS Event
14:00 Apr 22, 2008
Title	Improperly Installed Steel Angle Supports on Freezer Sublimer Vessel
Event Description	At 0900 CDT on 04-22-08, the Plant Shift Superintendent (PSS) was notified that the weight monitoring systems on vessels 2 on C-333 Unit 1 Cell 9, Unit 2 Cell 2, Unit 4 Cell 2 and Unit 4 Cell 9 freezer-sublimers showed weight changes when improperly installed steel angle supports welded to the vessel inlet piping were cut free. Each freezer sublimer vessel has a weight monitoring and trip system (high-high weight trip system) that prevents the over-filling of UF6 into the vessel. The high-high weight trip system is required by TSR 2.4.3.1 to prevent overfilling the freezer-sublimer vessels when in mode F/S 1 (freeze) or F/S 3 (cold standby). At the time of discovery, each freezer sublimer was in a non-applicable TSR mode F/S 6 (out-of-service). However, each freezer-sublimer has been routinely operated in TSR modes F/S 1 and F/S 3 over several years with the steel angle supports installed. The steel angle supports were likely installed to facilitate piping alignment during freezer-sublimer construction over fifteen years ago. The steel angle supports were not removed after construction. The presence of the steel angle supports may affect the performance the high-high weight trip system specified in TSR 2.4.3.1. All other installed freezer-sublimers were inspected and no additional steel angle supports were similarly connected. Engineering personnel are conducting a formal stress analysis to determine the stresses the steel supports may have had on the weight monitoring and trip system. There is no evidence that the weight limits specified in TSR 2.4.3.1 have been exceeded as a result of this issue. Pending further analysis, this event is conservatively being reported as a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> event in accordance with 10 CFR 76.120(c)(2)(i). This is an event in which equipment is disabled or fails to function as designed when: a.) the equipment is required by a TSR to prevent releases, prevent exposures to radiation and radioactive materials exceeding specified limits, mitigate the consequences of an accident, or restore this facility to a pre-established safe condition after an accident; b.) the equipment is required by a TSR to be available and operable and either should have been operating or should have operated on demand, and c.) no redundant equipment is available and operable to perform the required safety function. PGDP Assessment and Tracking Report No. ATRC-08-l 183; PGDP Event Report No. PAD-2008-12; Worksheet No. 44158 The NRC Senior Resident Inspector has been notified of this event. * * RETRACTION ON 5/29/2008 AT 1815 FROM BILLY WALLACE TO MARK ABRAMOVITZ * * * Retracted on 5/29/08, engineering calculations show that the error from the supports was less than the margin provided in the setpoint calculations. The licensee notified the NRC Resident Inspector. Notified the R2DO (Widman) and NMSS (Stablein).

ENS 44158 +/- *RETRACTED*
Where
Paducah Gaseous Diffusion Plant Paducah, Kentucky (NRC Region 2)
License number:	GDP-1
Reporting

10 CFR 76.120(c)(2)
Time - Person (Reporting Time:+18.75 h0.781 days <br />0.112 weeks <br />0.0257 months <br />)
Opened:	Matt Maurer 08:45 Apr 23, 2008
NRC Officer:	John Knoke
Last Updated:	May 29, 2008
44158 - NRC Website
v • d • e

v t e Emergency Notification System
Paducah Gaseous Diffusion Plant with 10 CFR 76.120(c)(2)
WEEKMONTHYEAR2014-05-08T15:24:00 [Table view]
[ENS list for Paducah Gaseous Diffusion Plant]

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