05000354/LER-2008-001, Reactor Recirculation Pump Motor Generator Set Scoop Tube Mechanical and Electrical Stop Over Speed Set Points Found Outside of Technical Specification Limits

Reactor Recirculation Pump Motor Generator Set Scoop Tube Mechanical and Electrical Stop Over Speed Set Points Found Outside of Technical Specification Limits

ML080850560
Person / Time
Site:	Hope Creek
Issue date:	03/18/2008
From:	Jamila Perry Public Service Enterprise Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LR-N08-056 LER-08-001-00
Download: ML080850560 (7)

LER-2008-001, Reactor Recirculation Pump Motor Generator Set Scoop Tube Mechanical and Electrical Stop Over Speed Set Points Found Outside of Technical Specification Limits

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x)
3542008001R00 - NRC Website

text

PSEG Nuclear LLC P.O. Box 236, Hancocks Bridge, New Jersey 08038-0236 0

Pn" (G Nuclear LLC MAR 1 8 2008 10CFR50.73 LR-N08-056 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-001 Hope Creek Generating Station Unit 1 Facility Operating License No. NPF'-57 Docket No. 50-354

Subject:

Licensee Event Report 2008-001 In accordance with 50.73(a)(2)(i)(B) and 50.73(a)(2)(v)(D), PSEG Nuclear LLC, is submitting Licensee Event Report Number 2008-001!.

I 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, John F. Perry Plant Manager Hope Creek Generating Station

Attachment:

Licensee Event Report 95-2168 REV. 7/99

Document Control Desk LR-N08-056 Page 2 cc:

Mr. S. Collins, Administrator - Region 1 U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Mr. R. Ennis, Licensing Project Manager - Hope Creek U.S. Nuclear Regulatory Commission Mail Stop 08B3 Washington, DC 20555-0001 USNRC Resident Inspector office - Hope Creek (X24)

Mr. P. Mulligan, Manager IV Bureau of Nuclear Engineering PO Box 415 Trenton, New Jersey 08625 I

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 8/31/2010

9-2007)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the digits/characters for each block) information collection.

3. PAGE Hope Creek Generating Station 05000 354 1

1 OF 5

4. TITLE Reactor Recirculation Pump Motor Generator Set Scoop Tube Mechanical and Electrical Stop Over Speed Set Points Found Outside of Technical Specification Limits

5. EVENT DATE

6. LER NUMBER 1

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEQUEATIA REV I

I FACILITY NAME MONTH DAY YEAR YEAR UMENTIAL EVMONTH DAY YEAR IN/A IFACILITY NAME 01 19 2008 2008 - 001 - 000 03 18 2008 JN/A

9. OPERATING MODE 1

10. POWER LEVEL 100

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)

El 20.2201(b)

El 20.2201(d)

El 20.2203(a)(1)

[3 20.2203(a)(2)(i)

E 20.2203(a)(2)(ii)

O 20.2203(a)(2)(iii)

[: 20.2203(a)(2)(iv)

El 20.2203(a)(2)(v)

El 20.2203(a)(2)(vi)

[E 20.2203(a)(3)(i)

El 20.2203(a)(3)(ii)

El 20.2203(a)(4)

El 50.36(c)(1 )(i)(A)

[I 50.36(c)(1)(ii)(A)

ED 50.36(c)(2)

El 50.46(a)(3)(ii)

ED 50.73(a)(2)(i)(A)

Z] 50.73(a)(2)(i)(B)

El 50.73(a)(2)(i)(C)

El 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(ii)(B)

El 50.73(a)(2)(iii)

El 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(v)(A)

[E 50.73(a)(2)(v)(B)

El 50.73(a)(2)(v)(C)

[] 50.73(a)(2)(v)(U)

El 50.73(a)(2)(vii)

[E 50.73(a)(2)(viii)(A)

El 50.73(a)(2)(viii)(B)

[E 50.73(a)(2)(ix)(A)

El 50.73(a)(2)(x)

El 73.71(a)(4)

El 73.71(a)(5)

El OTHER Specify in Abstract below or in

SAFETY CONSEQUENCES

The potential impact of this condition is a function of the reactor recirculation pump increasing flow transients (Reference UFSAR 15.4.5). If those analyzed transients were to have occurred, the potential existed that the Safety Limit Minimum Critical Power Ratio (SLMCPR) or the fuel rod thermal mechanical limits, respectively assuring avoiding centerline melt and 1% cladding plastic strain, could have been exceeded under the most limiting postulated conditions.

• An evaluation of the potential impact of the improper settings determined the recirculation flow increasing transients would not have resulted in any fuel limits being exceeded. The initial core power distribution conditions required at the beginning of a recirculation maximum flow event to ensure no fuel limits are exceeded during the event are enforced by the core flow dependent Minimum Critical Power Ratio (MCPRf) and Linear Heat Generation Rate (LHGRf) power distribution limits. The required MCPRf and LHGRf are.selected based upon the Technical Specification MG set scoop tube mechanical stop overspeed setting. The MCPRf and LHGRf were selected based upon the 109% setting. This evaluation determined the MCPRf and LHGRf required for the as-found condition of the settings and compared this requirement to the actual MCPR and LHGR operating conditions during the time period when the settings were non-conservative. The actual MCPR and LHGR operating conditions have been confirmed to have been within the initial conditions required to ensure no fuel limits would have been exceeded if a recirculation increasing flow transient had occurred with the non-conservative settings. Therefore there are no safety consequences to this event.

CAUSE OF OCCURRENCE An apparent cause evaluation was conducted.

The physical position of the stops did not change between the last performance of the surveillance test (June 17, 2006) and the January 19, 2008 performance of the test. Therefore, the non-conservative as found settings were due to a change in the correlations between the pump speeds and core flow (i.e.

change in Recirculation System hydraulic behavior). The following causes contributed to this occurrence.

o Alteration in Operational Practices in Cycle 14 Involvingthe Matching of Recirculation Loop Flows.

Prior to-June 2006, Hope Creek interpreted "Recirculation Loop Flow" (in TS 3.4.1.3) to refer to "Recirculation Loop Drive Flow". Following an initial failed attempt in Cycle 14 to set the MG stops, the procedure used to set the stops was revised. As part of the revision process, it was identified that "Recirculation Loop Flow" should have been associated with "Jet Pump Flow" to align with the LOCA analysis. The need to alter operational practices was identified on June 14, 2006. The alteration of the operational practice was initiated at the setting of the MG set stops on June17, 2006. The initial response was to blend the two practices and match both Recirculation Loop Drive Flows and Jet Pump Loop Flows within TS 3.4.1.3 requirements. It was not until early August 2006 that the change was completed and Jet Pump Loop Flows were being consistently matched by the Operating Shifts.

During this transition period, the correlations began to show the behavior change. Once the Jet Pump Loop Flows were being consistently matched, the correlations stabilized and reflected the-change in Recirculation System hydraulic behavior.

With matching Jet Pump Loop Flows, both Recirculation Loops were capable of pumping the same Recirculation Loop Drive Flows with significantly lower speeds (i.e. more efficient). This behavior change may have been related to hydraulic behavior in the lower plenum of the reactor vessel between.the Jet Pump discharges and the core inlet. With matching Jet PumpLoop flows, there is less radial flow between the structures in the lower*

plenum and possibly a lower backpressure for the Recirculation Loops; The magnitude of the behavior change may have been due to the degree of hydraulic asymmetries between the Recirculation Loops prior to the replacement of the "A" Recirculation Pump in RF14. Based on investigations performed as part of the cause evaluation, the impact of altering the operational practices was not predictable via industry benchmarking or an operating experience search.

o Change in Recirculation System Hydraulic Behavior Not Promptly Detected The change in Recirculation System hydraulic behavior was retrospectively evident in August 2006 when the implementation of the alteration in operational practices was largely completed. However, the Recirculation System trending program did not detect the change. Data was reviewed with a short-term focus. Data changes on a daily basis were interpreted as "noise". The charige following the operational practice alteration was not recognized.

Significance of Change in Recirculation System Hydraulic BehaviorNot Understood The interpretation was,.as long as the Recirculation MG Stops were set within the required frequency (atleast once per 18 months), no other actions were required. This interpretation was consistent with. known General Electric and industry practices.

There is a lack of guidance on when to perform the Technical Specification Surveillance Requirement 4.4.1.1.3 with respect to a refueling outage or plant change potentially impacting the maximum.Total Core Flow. There is no guidance on the conditions for trending data or extrapolating future performance.

Improved Standard Technical Specification (NUREG-1433) does. not include.a similar requirement for Recirculation M/G Set Stops so Jt could not be used to clarify Hope Creek Technical Specificaion Surveillance 4.4.1.1.3.

PREVIOUS OCCURRENCES

A review of previous reportable events at Hope Creek was performed to determine if a similar event had occurred.

• 10/08/2000 Hope Creek, LER 2000-010-000 Reactor Recirculation Pump Motor Generator Set Scoop Tube Mechanical and Electrical Stop Over speed Set points Found Outside of Technical Specification Limits. This LER described the "B" recirculation pump motor-generator set stops as being set non-conservatively high. Further investigation discovered that an error was made in the calibration of the.

stops and the Technical Specification required set point Values for the stops were never exceeded. The LER was retracted via PSEG Nuclear Letter LRN-01-0027 dated February 7, 2001.

CORRECTIVE ACTIONS

The mechanical and electrical stop set.points were adjusted to their proper settings.

The Recirculation System trending program will be reviewed to identify any near term changes needed to ensure compliance with TS Surveillance Requirement 4.4.1.1.3. Appropriate changes will be implemented.

The Recirculation System trending program will be benchmarked against industry best practices. Appropriate changes in the program will beimplemented.

The Technical Specification BASES will be reviewed. Revisions will be made as appropriate to provide guidance on the performance of, and compliance with TS Surveillance Requirement 4.4.1.1.3.

COMMITMENTS

This LER contains no commitments.