ENS 44158: Difference between revisions
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| event date = 04/22/2008 09:00 CDT | | event date = 04/22/2008 09:00 CDT | ||
| last update date = 05/29/2008 | | last update date = 05/29/2008 | ||
| title = Improperly Installed Steel Angle Supports | | title = Improperly Installed Steel Angle Supports on Freezer Sublimer Vessel | ||
| event text = 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. | | event text = 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. | 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. | ||
Revision as of 21:14, 1 March 2018
| 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 | |