ENS 43801

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v t e ENS Event
02:28 Nov 21, 2007
Title	Failure of Uf6 Release Detection System
Event Description	At 2028 CDST, on 11-20-07 the Plant Shift Superintendent (PSS) was notified that the C-333 Unit 6 Cell 7 UF6 Release Detection (PGLD) System failed to function when performing the twice per shift test firing. The test firing of the PGLD detector heads is required per TSR-SR 2.4.4.1-1. This PGLD System contains detectors that cover C-333 Unit 6 Cell 7, Section 3, and Section 4 of the cell bypass piping. At the time of this failure, unit 6 cell 7 and some areas of Section 3 and Section 4 of the cell bypass were operating above atmospheric pressure. TSR 2.4.4.1 requires that at least the minimum number of detector heads in the cell and in each defined section of the cell bypass are operable during steady state operations above atmospheric pressure. With the Unit 6 Cell 7 PGLD system inoperable, none of the required cell heads and only 2 of the required 3 heads in Section 3 and Section 4 of the cell bypass were operable. This PGLD System was declared inoperable, TSR LCO 2.4.4.1.B.1 and 2.4.4.1.C.1 was entered and a continuous smoke watch was put in place within one hour. Troubleshooting indicated the failure was not similar to writing failures recently experienced on other PGLD systems. The two components most susceptible to failure have been replaced and investigations continue into root cause. The system had functioned correctly when the previous test firing was performed at 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on 11-20-07. However, since the failure potentially occurred prior to the test firing at 2028 hours0.0235 days <br />0.563 hours <br />0.00335 weeks <br />7.71654e-4 months <br /> the event is 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." The NRC Resident Inspector has been notified of this event.

ENS 43801 +/-
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:+15.23 h0.635 days <br />0.0907 weeks <br />0.0209 months <br />)
Opened:	Calvin Pittman 17:42 Nov 21, 2007
NRC Officer:	John Mackinnon
Last Updated:	Nov 21, 2007
43801 - 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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