05000354/LER-2011-001, For Hope Creek Generating Station, Regarding HPCI Operation Credit in UFSAR Scenario Not Supported by Existing Documentation
| ML11277A019 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 09/22/2011 |
| From: | Doris Lewis Public Service Enterprise Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LR-N11-0294 LER 11-001-00 | |
| Download: ML11277A019 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3542011001R00 - NRC Website | |
text
PSEG Nuclear LLC P. 0. Box 236, Hancocks Bridge, NJ 08038 0 PSEG Nuclear LLC SEP 2 2 2011 LR-N11-0294 10 CFR 50.73 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-001 Hope Creek Generating Station Unit 1 Facility Operating License Number NPF-57 Docket Number 50-354
Subject:
Licensee Event Report 2011-001 In accordance with 10 CFR 50.73(a) (2) (v) (D), PSEG Nuclear LLC is submitting Licensee Event Report (LER) Number 2011-001.
Should you have any questions concerning this letter, please contact Mr. Philip J. Duca at (856) 339-1640.
No regulatory commitments are contained in the LER.
Sincerely, David P. Lewis Plant Manager Hope Creek Generating Station Attachment: Licensee Event Report 2011-001
Page 2 LR-N 11-0294 Document Control Desk cc:
Mr. W. Dean, Administrator - Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. R. Ennis, Project Manager Salem and Hope Creek U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 B1A 11555 Rockville Pike Rockville, MD 20852 USNRC Senior Resident Inspector - Hope Creek (X24)
P. Mulligan, Manager IV Bureau of Nuclear Engineering PO Box 415 Trenton, NJ 08625 Hope Creek Commitment Tracking Coordinator (H02)
INPO - LEREvents@lNPO.org
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Hope Creek Generating Station 05000354 1 of 4
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SQETA RE MOT DA YER FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEUMENILRE NTNDYOEA N/A YER NUMBER NO.
MONH DY ER N/
07 28 2011 2011 - 001 -
00 09 22 2011 N/A DOCKET NUMBER I
I
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 El 20.2201(d)
El 20.2203(a)(3)(ii)
[E 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
[E 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
E] 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
[3 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
[3 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
[3 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
Dl OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify in Abstract below or in Generator; and extreme winter conditions (i.e., resulting in maximum room inlet to outlet delta temperatures).
HPCI room area and differential temperatures are provided to detect a leak from the associated system steam piping.
The differential temperature isolation occurs when a leak has occurred. This function is diverse to high steam flow instrumentation. If the leak is allowed to continue without isolation, offsite dose limits may be reached. These functions are not assumed in any FSAR transient or accident analysis, since bounding analyses are performed for large breaks such as recirculation or MSL breaks. The current design for the HPCI system is to isolate when room temperature exceeds 160 degrees F or when the ventilation air temperature difference across the HPCI room reaches 70 degrees F.
Based on an engineering assessment (technical evaluation) it was determined that the HPCI system is not challenged by maximum room temperatures (isolation trip point at 160 degrees F) under summer or any winter operating conditions, nor by maximum HPCI differential temperatures (isolation trip point at 70 degrees F) under warmer ambient operating conditions. However, the ability of the system to perform its design function during extreme winter conditions (i.e., resulting in maximum room inlet to outlet differential temperatures) is not fully evaluated. This resulted in this condition being reported under 10CFR50.73 (a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of a SSC that are needed to mitigate the consequences of an accident.
With extremely low Safety Auxiliary Cooling System (SACs) {CC} temperatures, the ventilation inlet room temperature to the HPCI room will also be low. With the existing HPCI room temperatures and the loss of the HPCI room coolers due to the assumed failure of the 'A' EDG the differential temperature between the inlet and ventilation outlet temperatures may exceed 70 degrees F resulting in a HPCI isolation. Note: in this case the isolation would not be indicative of a steam leak in the HPCI room.
The technical evaluation provides the basis and documentation to determine the maximum HPCI room temperature and the ventilation air temperature difference across the HPCI room for the duration of the HPCI injection window. The technical 6valuation provides two separate room heat-up (i.e., GOTHIC model) cases: one to maximize the room temperature (i.e., summer condition, or hot supply air temperature) and the second to maximize the ventilation air temperature difference across the room (i.e., cold supply air temperature).
An Operability Evaluation has been prepared and is in place justifying continued operation. Based on the results of the technical evaluation, the HPCI system remains operable provided SACS temperatures remain greater than 45 degrees F.
In the case where the low probability event could occur and HPCI would trip, the LOCA condition would be mitigated by operation of the ADS valves, to depressurize the reactor and allow the low pressure emergency core cooling systems (ECCS) (i.e. Core Spray and LPCI) to ensure core coverage. Thisdesign provides redundancy of ECCS.
Additionally, although no credit can be taken in analyses for operator action, the Hope Creek emergency operating procedures provide direction to the operators to bypass the differential temperature trip, if needed, and maintain HPCI functional.
Although there is the potential for trip of the HPCI system because of the postulated low probability event, the redundant ECCS systems and the EOP. procedural guidance would ensure fuel peak clad temperatures would be maintained within design requirements thus minimizing the potential safety consequences and implications of the actual event.
There are no inoperable systems structures or components. Therefore a Safety System Functional Failure (SSFF) has not occurred as defined in Nuclear Energy Institute (NEI) 99-02. If the condition (not fully evaluated) was to occur, and HPCI was inoperable, then an SSFF would occur.
CAUSE OF OCCURRENCE The cause of this issue is a combination of a latent (original) design condition and the aggregate effect of design changes that were performed since plant licensing. The cumulative effect results in an overly conservative differential temperature potential isolation.
The original HPCI ventilation air temperature difference trip set point did not consider the impact of a pre-licensing calculation revision addressing HPCI room ventilation air temperature difference. One of the original set point calculation inputs was revised and the original set point was not recalculated to account for this revision.
Subsequent design changes included reduction in Safety Auxiliary Cooling System (SACS) minimum temperature from the original design of 65 degrees F to 32 degrees F. This change took credit for Filtration, Recirculation Ventilation System (FRVS) heaters. The FRVS heaters were later removed without considering the change to SACS minimum temperature.
PREVIOUS OCCURRENCES
A review of LERs for the three prior years at Hope Creek was performed to determine if a similar event had occurred. No similar occurrences were identified by this review.
CORRECTIVE ACTIONS
- 1. As a compensatory measure, a tracking LCO has been put in place to declare HPCI inoperable if SACs temperatures are below 45 degrees F. This LCO will be in place until other corrective actions have eliminated the potential event.
- 2.
A design change will be implemented to reduce the set points of the HPCI room cooler on-off temperatures so that the initial HPCI room temperature is maintained at a lower temperature. This will reduce the potential ventilation air temperature difference across the room during winter conditions (assuming the loss of room coolers and an initiation of HPCI) and prevent HPCI from isolating.
- 3. A clarification is being pursued to the applicability of UFSAR Table 6.3-6 to the postulated event.
- 4. A potential license amendment request to increase the Technical Specification differential room temperature isolation trip set point will be evaluated.
COMMITMENTS
This LER contains no commitments..
FORM 366A (10-2010)