ENS 47992
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ENS Event | |
|---|---|
20:14 Jun 4, 2012 | |
| Title | Reactor Coolant System in a Degraded Condition Due to an Instrument Rack Seismic Design Issue |
| Event Description | During a review of plant installed instrumentation racks inside containment, two instrument racks were identified that were over the analyzed weight for the seismic analysis. The instruments on these racks are used for reactor coolant pressure transmitters that are part of the Reactor Coolant System (RCS) pressure boundary, as they are connected via instrument lines to the RCS with no remote closure capabilities. A failure of these racks during a seismic event due to the excessive weight could result in an unisolable leak from the RCS within containment based on engineering judgment. This results in the RCS principal safety boundary being in a degraded nonconforming condition as the Updated Safety Analysis Report (USAR) specified Class 1 requirement is not being met for the current seismic design. Further engineering analysis is in progress to address the weight issue for these racks and mounting requirements. The plant is shutdown and in Mode 5 with the reactor vessel head removed, so RCS is not intact and not required to be for current plant conditions. This report is being made in accordance with 10CFR72(b)(3)(ii)(A) for a degraded condition.
The licensee has notified the NRC Resident Inspector.
On June 4, 2012, at 2059, Fort Calhoun Station made an 8-hour non-emergency notification for a degraded condition. Subsequent internal review has determined that the initial reporting criterion for degraded condition, 10 CFR 50.72(b)(3)(ii)(A), was incorrect. The instrument racks were identified as being over the analyzed weight for the seismic analysis. This is an unanalyzed condition, not a degraded condition. The report made on June 4, 2012 should have been made under 10 CFR 50.72(b)(3)(ii)(B), unanalyzed condition. The licensee has notified the NRC Resident Inspector. Notified R4DO (Werner). |
| Where | |
|---|---|
Fort Calhoun  Nebraska (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+1.75 h0.0729 days <br />0.0104 weeks <br />0.0024 months <br />) | |
| Opened: | John Fickle 21:59 Jun 4, 2012 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Aug 3, 2012 |
| 47992 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 522012016-08-25T20:23:00025 August 2016 20:23:00
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