ML18102B369

LER 97-005-00:on 970430,discovered Violation in Pressurizer Overpressure Protection Sys Ts.Caused by Inadequate Procedural Guidance.Revised Procedures for 115 Volt Vital Instrument Bus & 125 Vdc Bus operations.W/970530 Ltr

ML18102B369
Person / Time
Site:	Salem
Issue date:	05/30/1997
From:	Garchow D, Bernard Thomas Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-97-005-01, LER-97-5-1, LR-N97343, NUDOCS 9706090332
Download: ML18102B369 (5)

Text

Public SeNice Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038-0236 Nuclear Business Unit MAY 3 o 1997 LR-N97343 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 LER 311/97-005-00 SALEM GENERATING STATION - UNIT 2 FACILITY OPERATING LICENSE NO. DPR-75 DOCKET NO. 50-311 Gentlemen:

This Licensee Event Report (LER) entitled "Pressurizer Overpressure Protection System, Technical Specification Violation" is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR50. 73 (a) (2) (i).

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General Manager Salem Operations Attachment DVH C Distribution LER File 3.7 9706090332 90750005300311

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95-2168 REV. 6/94

NRC FORM 366 U.S. NUCLEAR REGULAT COMMISSION A OVED BY OMB NO. 3150-0104 ..>S. .II*

(4-95) EXPIRES 04/30/98 *

'-,-"' LICENSEE EVENT REPORT (LER)

ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS 1 MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS. ; ,.!

REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE :

LICENSING PROCESS ANO FED BACK TO INDUSTRY. __£QRWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INl'OAMATIO~

ANO RECORDS MANAGEMENT BRANCH (T-6 F33), U.S;JiUCLEAR (See reverse for required number of REGULATORY COMMISSION, WASHINGTON, DC 20555--0001, ANO TO THE PAPERWORK REDUCTION PROJECT (3150--0104), OFFICE OF digits/characters for each block) MANAGEMENT ANO BUDGET, WASHINGTON, DC 20503.

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

SALEM GENERATING STATION UNIT 2 05000311 1of4 TITLE (4)

Pressurizer Overpressure Protection System Technical Specification Violation EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR I SEQUENTIAL NUMBER IREVISIO NUMBER MONTH DAY YEAR FACILITY NAME Salem Unit 1 DOCKET NUMBER 05000272 FACILITY NAME DOCKET NUMBER 04 30 97 97 - 005 - 00 05 97 OPERATING 5 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more) (11)

MODE (9) 20.2201(b) 20.2203(a)(2)(v) X 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 000 20.2203(a)(1) 20.2203(a)(3)(i) 50. 73(a)(2)(ii) 50. 73(a)(2)(x)

LEVEL(10) n---+=20~.=22=0~3~(a~)(~2~)(~i)---+--i~2=0~.2=20=3~(a~)~(3+)(~ii),__---+--+-5=0~~7=3+(a~)(~2~)(~iii~)-----i1--+7=3~.7=1~-'--'-'--'--~ 1 LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (Include Aree Code)

Brian J. Thomas, Licensing Engineer 609-339-2022 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) 1 - C-AU_S_E_. ._ SY-ST_E_M- il- CO_M_P_O_NE-NT- il-M-A-NU_F_A_CT_U_RE-R-+-R-~-~o-:_1R_"8_}- i'1:1--....,CA_U_S_E -+-S-YS_T_EM-1--C-OM_P_O_N_EN-T-+-M-A-N-UF-A-CT_U_R_ER-+-R-~P-oo_:p-Ti{'_~_}E- 1 SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAV VEAR

• 1YES SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). x1NO DATE (15)

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

On April 30, 1997, a review of the Unit 2 control room narrative logs identified that from 0531 on March 23, 1997 until 2148 on March 27, 1997 the Reactor Coolant System (RCS) remained pre~surized with a channel of the Pressurizer Overpressure Protection System (POPS) inoperable. The POPS was inoperable for 112 hours0.0013 days <br />0.0311 hours <br />1.851852e-4 weeks <br />4.2616e-5 months <br /> and 17 minutes because the 2A 115 volt Vital Instrument Bus was aligned to its AC line regulator, and both POPS channels were being powered from the same DC Bus. At the time the transfer occurred, RCS temperature was 105 °F, and RCS pressure was 150 psig. This is a violation of Technical Specification 3.4.10.3 which requires that both channels of POPS be operable or the RCS be vented when RCS temperature is less than 312 °F. The cause of this occurrence is attributed to inadequate procedural guidance resulting from an inadequate implementation process in 1980 for license changes. This process has changed significantly since 1980.

Corrective actions include revision of the procedures for 115 volt Vital Instrument Bus and 125 VDC Bus operations to address POPS operability concerns when an instrument Bus is transferred from its normal alignment or 125 VDC loads are transferred to an alternate source.

This event is reportable in accordance with 10 CFR 50. 73(a)(2)(i)(B), any condition prohibited by the plant's Technical Specifications. It is likely that similar violations have occurred in the past at Unit 1 or Unit 2.

NRC FORM 366 (4-95)

NRC FORM 366A U.

• NUCLEAR REGULATORY COMMISSION (4-95)

• - LICENSEE EVENT REPORT (LER)

.TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SALEM GENERATING STATION UNIT 2 05000311 YEAR I SE~ri~J~AL I~1}'~~~~ 2 OF 4 97 - 005 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

PLANT AND SYSTEM IDENTIFICATION Westinghouse - Pressurized Water Reactor Power Operated Relief Valves {-/RV}*

• Energy Industry Identification System (EllS) codes and component function identifier codes appear in the text as (SS/CC)

CONDITIONS PRIOR TO OCCURRENCE At the time of the occurrence, Salem Unit 1 was shutdown and defueled. Salem Unit 2 was in Mode 5. In addition, the 2A 125 VDC Bus was removed from service, with selected loads transferred to the 28 125 VDC Bus.

DESCRIPTION OF OCCURRENCE During a simulator training session, a Nuclear Control Operator (NCO) identified that the UFSAR description of the Pressurizer Overpressure Protection System (POPS){-/RV} indicated a dependence on inverters which was not reflected in station procedures or Technical Specifications. UFSAR Section 7.6.3.3 states, "A 'loss of station power' will have no effect on the POPS since the protection logic power is provided by inverters, and control power for the relief valves originates at the batteries." The NCO questioned whether the requirements of Technical Specification 3.4.10.3 were met when power for the POPS logic instrumentation was transferred to an alternate source. Review of this issue determined that transfer of AC or DC power for POPS components to an alternate source resulted in the respective channel being inoperable, and TS 3.4.10.3 should. have been entered.

Technical Specification 3.4.10.3 states: "At least one of the following overpressure protection systems shall be OPERABLE:

a. T.wo Pressurizer Overpressure Protection System relief valves (POPS) with a lift setting of less than or equal to 375 psig, or

b. The Reactor Coolant System (RCS) depressurized with an RCS vent of greater than or equal to 3.14 square inches."

Technical Specification 3.4.10.3 is applicable when the temperature of one or more of the RCS cold legs is less than or equal to 312 °F, except when the reactor vessel head is removed.

A review of the Unit 2 control room narrative logs determined that at 0531 on March 23, 1997 the 2A Instrument Bus was transferred to its AC line regulator. This was done to facilitate removal of the 2A 125 VDC Bus from service. At the time the transfer occurred, RCS temperature was 105 °F, and RCS pressure was 150 psig. The condition existed until 2148 on March 27, 1997 when the 2A Instrument Bus was transferred back to its inverter. This action rendered one channel of POPS inoperable for 112 hours0.0013 days <br />0.0311 hours <br />1.851852e-4 weeks <br />4.2616e-5 months <br /> and 17 minutes which exceeded the TS allowed out of service time without venting the RCS, and was a violation of TS 3.4.10.3.

NRC FORM 366A (4-95))

..,. NRC FORM 366A U.

• NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3)

SALEM GENERATING STATION UNIT 2 05000311 YEAR I SEQUENTIAL NUMBER IREVISION NUMBER 3 OF 4 97 - 005 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

The Final Safety Analysis Report (FSAR) from 1978 stated that "A 'loss of station power' will not affect the POPS since the protection logic power is provided by inverters and control power for the relief valves originates at the batteries." This same statement is in the current UFSAR. The POPS system response to a loss of station power was part of the original licensing basis for the POPS, and the invulnerability of the POPS to a loss of station power was predicated on the continuous availability of inverter power to the protection system inst.rumentation associated with the POPS logic. Therefore, the normal and emergency power supplies are required to support operability of the POPS. Transferring the A or B 115 volt Instrument Bus to its AC line regulator renders a POPS channel inoperable because TS 3.0.5 is not applicable in Modes 5 and 6. TS 3.0.5 allows, in part, a system, subsystem, train, component or device to be considered operable for TS purpose if it is inoperable solely because its normal or emergency power source is inoperable.

In addition, the review of the narrative logs identified that the control power for .both channels of the POPS relief valves were selected to the same battery (2B) during the period when the 2A 125 VOC Bus was out of service and the .2A Instrument Bus was aligned to its AC line regulator. The POPS was designed as a "protection grade" system in accordance with the applicable portions of IEEE 279 - 1971. In order for a component to be considered protection grade, train separation must be maintained. Train separation was not maintained for the POPS relief valves when they were aligned to the same battery. Aligning the control power for both channels of the POPS relief valves to the same battery also rendered one channel of POPS inoperable.

Only the recent narrative logs were reviewed; however, it is likely that similar violations occurred in the past at Unit 1 and Unit 2.

CAUSE OF OCCURRENCE The cause of this occurrence is attributed to inadequate procedural guidance resulting from an inadequate implementation.process in 1980 for license changes. This process has changed significantly since 1980.

The license change was submitted in 1978 and implemented in 1980. Correspondence related to the license change submittal clearly stated a dependence on the inverters to address a loss of station power. However, the Limiting Conditions for Operation and Surveillance Requirements for the POPS made no reference to POPS operability with respect to Instrument Bus power, and procedures for operation of the 115 volt Vital Instrument Bus inverters and 125 VOC Buses were not revised to reflect the POPS concern either.

PRIOR SIMILAR OCCURRENCES There are no similar reportable occurrences for Salem Units 1 & 2 in the last two years. However, the Technical Specification Surveillance Improvement Project (TSSIP) has identified a variety of historical conditions involving inadequate implementation of Technical Specifications into procedures. Some of the conditions described in the supplements to TSSIP LER 272/96-005 resulted in part from inadequately implemented license changes.

NRC FORM 366A (4*95))

,* NRC FORM 366A u. . NUCLEAR REGULATORY COMMISSION II (4-95)

\ LICENSEE EVENT REPORT (LER) , i T ',,

J TEXT CONTINUATION *1 ll============================~========n===-"*:.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE {,S)

SALEM GENERATING STATION UNIT 2 05000311 YEAR I SE,fill,i~JkAL I~'iiv~~~~ 4 OF

• 4 97 - 005 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

SAFETY CONSEQUENCES AND IMPLICATIONS There were no adverse safety consequences as a result of this event.

The 2A 115 volt Vital Instrument Bus was aligned to its AC line regulator for a total of 112 hours0.0013 days <br />0.0311 hours <br />1.851852e-4 weeks <br />4.2616e-5 months <br /> and 17 minutes. In addition, control power for the channel A POPS relief valve (2PR1) was transferred from 2A 125 VDC Bus to 2B 125 VDC Bus when the 2A Bus was removed from service. As a result, the 'A' POPS logic channel was inoperable in excess of the time allowed by Technical Specification 3.4.10.3, without venting the RCS, by a total of 88 hours0.00102 days <br />0.0244 hours <br />1.455026e-4 weeks <br />3.3484e-5 months <br /> and 17 minutes.

During the period when the 'A' POPS channel was inoperable, a steam bubble in the Pressurizer was used to maintain RCS pressure. The steam bubble minimized the potential for over pressurization of the RCS. All three Unit 2 diesel generators were operable/available throughout the entire period, thus the likelihood that a loss of station power could have adversely affected the POPS was minimal. In addition, no maintenance activities were in progress which had the potential to affect operability of the 2B 125 VDC Bus, and no.

challenges to the pressure relief function of the POPS occurred.

The health and safety of the public were not affected.

CORRECTIVE ACTIONS

1. The Unit 2 procedures for 2A and 2B 125 VDC Bus operation were revised to indicate that shifting POPS components to the alternate DC supply will result in one inoperable POPS channel.

2. The Unit 2 procedures for 2A and 2B 115 volt Vital Instrument Bus operation were revised to indicate that the associated POPS channel is inoperable if the A or B Instrument Bus is not powered by its respective inverter.

3. The Unit 1 procedures for 1A and 1B 125 VDC Bus operation and 115 volt Vital Instrument Bus operation will be revised prior to Unit 1 entry into Mode 6. *

4. A review of Technical Specifications and the USFAR was performed to determine the extent of generic implications, and no additional concerns were identified. The original design criteria for the POPS required a protection grade actuation logic. The POPS is required to be operable whenever RCS temperature is less than 312 °F which results in a protection system that is required to have operable normal and emergency power supplies in Modes 5 and 6. The review determined that, in general, the protection systems at Salem are designed such that the associated trip or actuation occurs upon a loss of power and are only required to be operable in Modes 1 through 4. With the exception of the POPS, the protection systems which have operability requirements for Modes 5 or 6 are also are designed such that the associated trip or actuation occurs upon a loss of power. Since the POPS protection logic requires power to initiate protective action, its dependence on the normal and emergency AC and DC power sources while In Modes 5 and 6 makes it unique with respect to other protection logics in use at Salem.

NRC FORM 366A (4-95))