ENS 41844
ENS Event | |
|---|---|
21:10 Jul 14, 2005 | |
| Title | Station Blackout Temperature Analysis Higher than Rcic Governor Documentation |
| Event Description | During fact gathering in response to an NRC inspection inquiry, it was determined that documentation does not exist that demonstrates that the Reactor Core Isolation Cooling (RCIC) Electronic Governor Module (EGM) would be able to operate during the required Station Blackout (SBO) coping mission time at the postulated post SBO RCIC room temperature of 206.4F. Current documentation supports operation up to 150F.
The EGM is a skid-mounted module that provides speed control signals for the RCIC Woodward Governor. Failure of the EGM would result in a loss of speed control for the RCIC turbine. This could result in an overspeed, underspeed or no change condition. Overspeed of the turbine would result in a mechanical overspeed trip. This device is not in the EQ program but is Augmented Quality. RCIC continues to perform its Technical Specification required functions as defined in the Bases of Technical Specification (TS) 3.5.3. The TS function is to respond to transient events by providing makeup coolant to the reactor. The RCIC Room temperatures for the postulated TS transient events is less than the currently documented component qualification temperature. The RCIC is not an ESF system and no credit is taken in the safety analysis for RCIC system operation but is retained in the TS based on its contribution to the reduction of overall plant risk per Criterion 4 of 10 CFR 50.36. The RCIC system design requirements ensure that the criteria of 10CFR50 Appendix A, GDC 33, are satisfied. Due to the lack of supporting documentation for the EGM, the beyond design basis regulatory SBO rule requirements of 10 CFR 50.63 may not be met. This condition could potentially result in an unanalyzed condition that could significantly degrade plant safety and is therefore reportable under 10 CFR 50.72(b)(3)(ii). An analysis of the RCIC Room Heat Up Rate calculation is being performed as there are conservatisms built into the calculation that when removed will result in a lower temperature than 206.4F. Additional actions in progress include, establishing appropriate protected pathways to minimize the potential for a Loss Of Off-Site Power which could result in a SBO, performance of temperature qualification testing at SBO temperatures for the EGM, and performance of an extent of condition review for remaining RCIC components to ensure temperature qualification is met for the SBO rule. In parallel with temperature qualification testing, a modification to relocate the EGM to an area outside the RCIC room that has a lower SBO profile temperature is being pursued in the event that temperature qualification is not successful. The licensee notified the NRC Resident Inspector.
A 8-hour notification was made on July 14, 2005, in accordance with 10 50.72(b)(3)(ii)(B), Unanalyzed condition. The report was made because documentation did not support the continued operation of Reactor Core Isolation Cooling (RCIC) Electronic Governor Module (EGM) during the required Station Blackout (SBO) coping mission. Since the initial report, the post SBO room heatup calculation was evaluated and determined that the decay heat removal function during the SBO coping mission was met. The decay heat removal function during SBO coping period is achieved by either High Pressure Core Spray (HPCS) or RCIC systems. In addition, the other RCIC functions (i.e., Remote Shutdown, and Safe Shutdown Fire) were evaluated and determined to be met. Since the RCIC functions and the decay heat removal and vessel inventory functions during the SBO coping mission were maintained, the plant was not in an unanalyzed condition and this issue is not reportable. Since the condition is not reportable EN 41844 is retracted. The licensee notified the NRC Resident Notified R3DO (K. O'Brien) |
| Where | |
|---|---|
LaSalle  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+-0.45 h-0.0188 days <br />-0.00268 weeks <br />-6.1641e-4 months <br />) | |
| Opened: | Jeffrey Williams 20:43 Jul 14, 2005 |
| NRC Officer: | Mark Abramovitz |
| Last Updated: | Aug 16, 2005 |
| 41844 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 532132018-02-15T17:00:00015 February 2018 17:00:00
[Table view]10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Notification of Unanalyzed Condition Affecting Accident Mitigation for Tornado Generated Missiles ENS 506752014-12-12T21:00:00012 December 2014 21:00:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition with Reactor Core Isolation Cooling ENS 424052006-03-11T06:30:00011 March 2006 06:30:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Unanalyzed Condition ENS 423482006-02-20T06:23:00020 February 2006 06:23:00 10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(a)(1)(i), Emergency Class Declaration, 10 CFR 50.72(b)(3)(iv)(A), System Actuation Site Area Emergency - Reactor Scram ENS 418442005-07-14T21:10:00014 July 2005 21:10:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Station Blackout Temperature Analysis Higher than Rcic Governor Documentation ENS 413662005-02-02T21:42:0002 February 2005 21:42:00 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition Single Failure Vulnurability in Ac Auxiliary Power System 2018-02-15T17:00:00 | |