ML18101A414

LER 94-017-00:on 941117,listed Assumptions Could Place Unit 1 Outside Design/Licensing Basis for Pops Analysis.Pdp Operation Not Considered in Any Design Basis Pressure Limit of 450 psig.W/941214 Ltr

ML18101A414
Person / Time
Site:	Salem
Issue date:	12/14/1994
From:	Hagan J, Pastva M Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
REF-PT21-94 LER-94-017-01, LER-94-17-1, NUDOCS 9412230045
Download: ML18101A414 (7)

Text

e e OPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station December 14, 1994 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attn.: Document Control Desk SALEM GENERATING STATION LICENSE NO: DPR-70 DOCKET NO: 50-272 UNIT NO: 1 LICENSEE EVENT REPORT NO. 94-017-00 This Licensee *Event Report is being submitted pursuant to the requirements of Code of Federal Regulation 10CFR50.73(a) (2) (i) (B). Issuance of this report is required within thirty (30) days of event discovery.

Sincerely, anager -

Operations MJPJ:vs SORC 94-094 C Distribution LER File 9412230045 941214 PDR ADOCK 05000272 S PDR fti'

'/ t The power is in your hands.

~ri-,(n(\ 95-2189 REV 7-92

NRC FORM 366

• NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31 /95 ESTIMATED BURDEN PEA RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HAS. FORWARD LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR

.REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF (See reverse for required mynber of digits/characters for each block) MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.-

FACILITY NAME (1) DOCKET NUMBER (2) PAGE (3)

Salem Generating Station - Unit 1 05000 272 1OF5.

TITLE (4) i.naciequate Margin ror .l:'ressurizer Overpressure Protection During Low Temperature Conditions (Applicable to Unit 1). . _

EVENT DATE (5) LER NUMBER (6 REPORT NUMBER (7\ OTHER FACILITIES INVOLVED (8)

FACILITY NAME DOCKET NUMBER SEQUENTIAL REVISION YEAR.

MONTH DAY YEAR YEAR MONTH DAY NUMBER NUMBER 05000 FACILITY NAME DOCKET NUMBER 11 17 94 94 -- 017 -- 00 12 *14 94 05000 OPERATING. THIS REPORT IS SUBMITIED PURSUANT TO THE REQUIREMENTS OF 10 CFR I: (Check one or more (11) 1 MODE (9) 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b)

POWER 20.405(a}(1)0) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)

LEVEL (10) 100% 50.73(a)(2)(vii) 20.405(a)(1)(ii) 50.36(c)(2) x OTHER 20.405(a) (1) (iii) 50. 73 (a)(2)(i) 50.73(a) (2)(viii) (A) (Specify in Abstract below and in Text, NRC 20.405(a)(1)(iv) x 50.73(a)(2)(ii) 50:73(a)(2)(viii)(B) Form 366A) 20.405 (a}(1 )(v) 50.73(a)(2)(iii) 50.73(a}(2)(x) 10CFR21 LICENSEE CONTACT FOR THIS LER 712)

NAME TELEPHONE NUMBER (Include Area Code)

Michael J. Pastva, .. Jr. LER Coordinator 609 339-5165 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13l REPORTABLE

... REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO NPRDS TO NPRDS SUPPLEMENTAL REPORT EXPECTED 114) EXPECTED MONTH DAY YEAR I YES (If yes, complete EXPECTED SUBMISSION DATE) x NO SUBMISSION DATE (15)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On 11/17/94, it was determined that the following realistic assumptions could place Unit 1 outside the design/licensing basis for Pressurizer Overpressure Protection System (POPS) analysis should a safety injection (SI) signal occur:

• Reactor Coolant System (RCS) temperature < 200°F, 1 Reactor Coolant Pump (RCP) in operation, Positive Displacement Charging Pump (PDP) in service, and power available to a maximum of 1 Centrifugal Charging Pump (CCP) . Under these conditions, an SI signal could result in a peak RCS pressure of 474 psig from combined flow from the PDP and the CCP, which exceeds the .current design basis pressure limit of 450 psig.

This concern is not applicable to Unit 2. This event occurred because PDP operation was not considered in any design basis analysis, based on a POPS lift setting of </= 375 psig. Current operating procedures limit RCP operation in Mode 5 to 1 pump, and require power be removed from the SI pumps in Mode 4 (350°F >Tave, > 200°F) . Residual Heat Removal relief valve RH3 is required to be available when RCS temperature is </= 200°F and when the PDP is operating. Code case relief will be requested to increase the pressure/temperature limits operating margin for the POPS during Low Temperatur~_ Oyerpressure conditions. This LER is also intended to satisfy reporting requirements of 10CFR21.

NRG FORM 366 (5-92)

e

'REQUIRED NUMBER OF-DIGITS/CHARACTERS FOR EACH BLOCK .

BLOCK NUMBER OF TITLE NUMBER DIGITS/CHARACTERS

• 1 UPTO 46 FACILITY NAME 8 TOTAL 2 DOCKET NUMBER 3 IN ADDITION TO 05000 3 VARIES PAGE NUMBER ..

4 UP TO 76 TITLE 6TOTAL 5 EVENT DATE 2 PER BLOCK 7TOTAL 2 FOR YEAR 6 LEA NUMBER 3 FOR SEQUENTIAL NUMBER 2 FOR REVISION NUMBER 6 TOTAL 7 REPORT DATE 2 PER BLOCK UP TO 18 - FACILITY NAME 8 OTHER FACILITIES INVOLVED 8 TOTAL - DOCKET NUMBER 3 IN ADDITION TO 05000 9 1 OPERATING MODE 10 3 POWER LEVEL 1 "*

11 REQUIREMENTS OF 10 CFR CHECK BOX THAT APPLIES UP TO 50 FOR NAME 12 LICENSEE CONTACT 14 FOR TELEPHONE CAUSE VARIES 2 FOR SYSTEM 13 4 FOR COMPONENT EACH COMPONENT FAILURE 4 FOR MANUFACTURER NPRDS VARIES 1

14 SUPPLEMENTAL REPORT* EXPECTED CHECK BOX THAT APPLIES 6TOTAL 15 EXPECTED SUBMISSION DATE 2 PER BLOCK

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Docket Number LERNumber Page Unit 1 50-272 94-017 2 of5 Plant and System Identification:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are shown in the text as {xx}

Identification of Occurrence:

Inadequate Margin For Pressurizer Overpressure Protection During Low Temperature Conditions (Applicable To Unit 1)

Event Date: November 17, 1994 Report Date: December 14, 1994 This report was initiated by Incident Report 94-419 This report is intended to also satisfy reporting requirements of 10CFR21.

Initial Conditions:

Mode 1 Reactor Power 100% Unit Load 1150 MWe Description of Occurrence:

The current bases for Technical Specifications (TSs) 3/4.4.9.3 states that one Pressurizer Overpressure Protection System (POPS) relief valve, at a lift setting of </= 375 psig, provides adequate relieving capacity in the event of an overpressure transient that includes inadvertent start of a safety injection (SI) pump (mass addition transient) into a water solid Reactor Coolant System (RCS). Subsequently, it has been determined that the following realistic mass addition transient assumptions could place Unit 1 outside the design and licensing basis POPS analysis should an SI signal occur:

- RCS temperature </= 200°F

- One Reactor Coolant Pump (RCP) in operation Positive Displacement Charging Pump (PDP) in service

- Power supply available to a maximum of One Centrifugal Charging Pump (CCP)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Docket Number LERNumber Page Unit 1 50-272 94-017 3 of5 Description of Occurrence: (cont'd)

At 1746 hours0.0202 days <br />0.485 hours <br />0.00289 weeks <br />6.64353e-4 months <br /> on November 17, 1994, the Nuclear Regulatory Commission was notified of this event, pursuant to the requirements of 10CFR50.72(b) (1) (ii).

Under the above conditions, an SI signal could result in a combined flow from the PDP and the CCP with a peak RCS pressure of 474 psig. This exceeds the current design basis pressure limit of 450 psig for Salem Unit 1.

Analysis of Occurrence:

Background

POPS protects the RCS from exceeding the TS pressure/temperature (P/T) limits for plant heatup (reference TS Figure 3.4-2) and cooldown (reference TS Figure 3.4-3) by opening the Power Operated Relief Valves (PORV) during low temperature overpressure (LTOP) transients (RCS cold leg temperature below 312°F) . Per existing design bases, either of the two PORVs has adequate relieving capacity to protect the RCS from overpressurization when the transient is limited to either (1) the start of an idle RCP with the secondary water temperature less than or equal to 50°F above the RCS cold leg temperature (heat addition), or (2) the start of an SI pump and resultant injection into a water solid RCS (mass addition). The pressure limit at the low temperature end of the P/T curves is presently 450 psig for Unit 1,- as read from the current heatup and cooldown curves.

The Nuclear Steam Supply System (NSSS) vendor identified in a letter, dated March 15, 1993, a non-conservatism in the calculation for peak pressure for the heat input and mass addition transients that affects both Salem Units 1 and 2. The concern was that the difference between the wide range pressure transmitters (PT403 and PT405) elevations, which sense hot leg pressure and the reactor vessel midplane (where the TS heatup and cooldown P/T limits are defined) with the RCPs operating was not considered in the original Salem POPS analysis. Calculations were performed to address the identified concern and necessary limits were met.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Docket Number LERNumber Page Unit 1 50-272 94-017 4 of5 Analysis of Occurrence: (cont'd)

Present Situation Since the satisfactory completion of this evaluation, it has been determined that the PD~, if already in operation, would continue to operate upon initiation of a SI signal if offsite power remained available. During this postulated event, letdown would automatically isolate as part of the SI actuation. The additional flow from the PDP is a concern for the limited period of time when the RCS is</= 200°F (Mode 5), the PDP is in operation, and one (1) CCP has its associated power supply available. The combined flow of 665 gpm from the PDP (105 gpm) and the CCP (560 gpm) is now considered the most limiting mass addition transient.

PSE&G has re-analyzed this mass addition event using the GOTHIC computer code assuming a bounding maximum pump flow rate of 675 gpm. The resulting peak pressure is 474 psig, which exceeds the current limit of 450 psig for Salem Unit 1.

For the heat addition transient (i.e., the start of an idle RCP with the secondary water temperature </= 50°F abo"ve the RCS cold leg temperature), the peak pressure is 449 psig, below the POPS limit of 450 psig for Salem Unit 1.

Additional margin on the TS P/T curves can be obtained when operating with POPS (RCS cold legs </= 312°F) by taking credit for ASME Code Case N-514. The code case allows exceeding the P/T limits calculated in accordance with 10CFRSO, Appendix G, by 10%.

As compensatory action, administrative controls ensure that Residual Heat Removal (RHR) relief valve RH3 is available and the associated RHR isolation valves are in the open position. PSE&G has determined that RH3 has similar relieving capacity to that of a PORV. This action is only necessary when RCS temperature is

</= 200°F, the PDP is in operation and a CCP has power available.

Apparent Cause of Occurrence:

This event is attributed to "Design", as classified in Appendix B of NUREG-1022. This occurred because the NSSS vendor had not considered the PDP operation as part of any design basis analysis.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Docket Number LERNumber Page Unit 1 50-272 94-017 5 of5 Prior Similar Occurrence:

No other prior similar occurrences have been identified related to this design deficiency.

Safety Significance:

This event is reportable in accordance with the requirements of 10CFR50.73(a) (2) (ii) (B), due to the POPS not being able to meet its current design basis. This event had minimal safety significance, based upon the additional relieving capacity of RH3 and/or with the 10% allowance, permitted by use of Code Case N-514.

Corrective Action:

As interim corrective action to ensure compliance with the POPS design basis, the following administrative controls are in place:

Salem Unit 1 operating procedures limit RCP operation in Mode 5 to one pump, and require that power be removed from the SI pumps in Mode 4 (350°F >Tave, > 200°F). RH3 is required to be available to ensure the current P/T limits are met when RCS temperature is

</= 200°F, when the PDP is in operation. Similar administrative controls for Salem Unit 2 are in place, although RH3 is not needed to meet the corresponding Unit 2 P/T limit.

A submittal will be made to the NRC requesting application of Code Case N-514. This additional margin increases the P/T limits operating margin for the POPS during LTOP conditions.

n General Manager Salem Operations MJPJ REF: SORC Mtg.94-094