ML18101B206

LER 96-001-00:on 960103,discovered Insufficent Thermal Overload Relay Heater Margin.Caused by Inadequate Design of TOLs in 1970s.Issued Calculation ES-18.007 for Sizing of Thermal Overload Heaters for SR Rotating loads.W/960206 Ltr

ML18101B206
Person / Time
Site:	Salem
Issue date:	02/02/1996
From:	Hassler D, Warren C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-96-001, LER-96-1, LR-N96020, NUDOCS 9602080103
Download: ML18101B206 (5)

Text

PS~G *

• Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038-0236 Nuclear Business Unit FEB 021996 LR-N96020 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Gentlemen:

LER 272/96-001 SALEM GENERATING STATION - UNIT 1 FACILITY OPERATING LICENSE NO. DPR-70 DOCKET NO. 50-272 This License Event Report entitled urnsufficient Thermal Overload Relay Heater Margin" is being submitted pursuant to the requirements of the Code of Federal Regulations 10 CFR5 0 . 7 3 (a) ( 2) (ii) .

Sincerel~

~W~ren General Manager -

Salem Operations Attachment SORC Mtg.96-013 KBH/tcp C Distribution LER File 3.7 080()35 9602080103 960202 PDR ADOCK 05000272 s PDR J J"i', ": '>*

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LY 95*2168 REV.

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Attachment A The following* item represents commitments that Public Service Electric & Gas (PSE&G) made to the Nuclear Regulatory Commission (NRC) relative to this LER (272/96-001-00) ., The commitment is as follows:

1. Modifications required to replace undersized TOL's will be completed prior to the respective start-up of Salem Units 1 and 2.

NRCFORM 366 U.S. NUCL AR REGULATORY COMMISSION APP OVED BY OMB NO. 3150-0104 (4-95) EXPIRES 04/30/98 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS.

REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENSEE EVENT REPORT (LER) LICENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (T~ F33), U.S. NUCLEAR (See reverse for required number of REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF digits/characters for each block) MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAllE (1) 1 uu.-1\ET NUllBER (2) PAGE (3)

Salem Generating Station - Unit 1 05000272 1 OF3 TITLE (4)

Insufficient Thermal Overload Relay Heater Margin EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR SEQUENTIAL NUMBER IREVISION NUMBER MONTH DAY YEAR FACILITY NAME DOCKET NUMBER I Salem Generating Station

• Unit 2 05000311 DOCKET NUMBER FACILITY NAME 01 03 96 96 - 001 - 00 02 02 96 05000 OPERATING 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) 50. 73(a)(2)(i) 50. 73(a)(2)(viii)

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

LEVEL (10) 0 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50. 73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50. 73(a)(2)(iv) OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50. 73(a)(2)(v) Spec~in Abstract below or in C Form 366A 20.2203(a)(2)(iv) 50.36(c)(2) 50. 73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (Include Area Code)

Dennis V. Hassler - LER Coordinator 609-339-1989 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13}

CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDS TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR SUBMISSION

\YES (If yes, complete EXPECTED SUBMISSION DATE). X \NO DATE (15)

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

In January 1996 a calculation was issued to perform sizing determinations for selected rotating equipment Thermal Overload Heaters (TOLs) on 230V and 460V safety related electrical buses, taking into consideration installed ambient temperatures and degraded voltage conditions. The results of this. calculation showed that 36 electrical loads had undersized TOLs that could cause spurious tripping of their respective loads. The original sizing of TO Ls at the Salem Nuclear Generating Station was performed by selecting the heater from the vendor catalog using vendor recommended selection criteria. Installed ambient temperatures and degraded voltages were not fully considered in the early 1970's when the plant was designed. Engineering has issued updated TOL design criteria as well as calculations for sizing TO Ls for all safety related rotating loads and motor operated valves. In addition modifications to replace undersized TO Ls will be completed prior to the respective startups of Salem Units 1 and 2.

This issue is reportable under 1 0 C FR5 0 . 7 3 ( a ) ( 2 ) ( ii ) " ... the nuclear power plant being outside the design basis of the plant. If NRC FORM 366 (4-95)

NRG FORM 366A U.~. UCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 05000272 YEAR I SEQUENTIAL NUMBER IREVISION NUMBER 2 OF 3 Salem Generating Station - Unit 1 96 - 001 - 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

PLANT AND SYSTEM IDENTIFICATION Westinghouse - Pressurized Water Reactor 230 V Motor Control Center (MCC) {ED/--}*

460 V Motor Control Center (MCC) {ED/--}*

• Energy Industry Identification System (EIIS) codes and component functions are identified in the text as {SS/CC}.

CONDITIONS PRIOR TO OCCURRENCE At the time of the above occurrence, both Salem units were in a self-imposed extended shutdown.

Unit 1: Defueled - 0% power Unit 2: Defueled - 0% power There were no structures, components, or systems that were inoperable at the start of the event that contributed to the event.

DESCRIPTION OF OCCURRENCE Following the October 1994 Service Water System Operational Inspection a corrective action was implemented for engineering to develop a calculation verifying Thermal Overload Heater (TOL) sizing. In April 1995 calculation ES-18.007, Rev. O, "Rotating Equipment Thermal Overload Sizing Calculation," was issued for Service Water Motor Control Center TOLs. No reportable conditions were found as a result of this calculation. In January 1996, Rev. 1 of the calculation was issued. The results of th{s calculation showed that under installed ambient temperature conditions accompanied by degraded voltage, 36 electrical loads had undersized TOLs that did not meet the required overload trip margin specified in Technical Standard, ND.DE-TS.ZZ-2012 (Q), Rev. O, Dated 7/13/94. This deficiency could cause spurious tripping

~f their respective loads.

PRIOR SIMILAR OCCURRENCES During the previous two years there were two LERs that attributed their root cause to design deficiencies and were similar in nature to this LER. LER 272/94-011-00 evaluated a design deficiency in the Salem Unit 1 circulating water bus Under Voltage (UV) protection and LER 311/94-008-00 evaluated a design deficiency in the Salem Unit 2 Feedwater control system at low reactor power levels.

NRC FORM 366A (4-95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 05000272 YEAR I SEQUENTIAL NUMBER IREVISION NUMBER 3 OF 3 Salem Generating Station - Unit 1 96 - 001 - 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

CAUSE OF THE OCCURRENCE Original sizing of TOLs at the Salem Nuclear Generating Station was performed by selecting the heater from the vendor c~talog without detailed consideration and documentation of specific design and environmental conditions. The TOLs were sized to Field Directive S-C-El55-EFD-0169 issued by PSE&G's Engineering and Construction Department. The directive did not account for the TOLs' installed ambient temperature conditions and degraded voltage. The root cause of this event was inadequate design of the TOLs in 1970's.

SAFETY SIGNIFICANCE The safety significance of this event was low. Applying current design criteria for TOLs, engineering has determined spurious tripping of the evaluated loads could occur during a degraded voltage condition. However, the condition of degraded voltage, a design basis accident, and multiple combinations of loads which may experience a spurious TOL trip, all occurring concurrently was judged to be of low probability and therefore was not evaluated. A review of previous reportable events involving a

• degraded voltage condition revealed two occurrences at the Salem station. The first occurrence was reported in LER 91-024-00 and involved a degraded voltage condition as a result of a lightning strike. The LER concluded that the health and safety of the public was not affected by this event. The second occurrence was reported in LER 86-007 and involved a degraded voltage condition as a result of vital busses being overloaded by startup currents produced by safeguards equipment. A review of this LER has. determined that the health and safety of the public was not affected. Based on no other reportable incidents of degraded voltage conditions, the undersized TOLs described in this LER did not affect the health and safety of the public.

CORRECTIVE ACTIONS

1. Nuclear Electrical Engineering has issued Technical Standard ND.DE-TS.ZZ-2012 (Q) for the design and sizing of motor starters, circuit breakers and thermal overload relay heaters. This supersedes PSE&G Field Directive S-C-E155-EFD-0169.

2. Electrical engineering has issued calculation ES-18.007 for the sizing of thermal overload heaters for all safety related rotating loads.

3. Electrical engineering has issued calculation ES-18.006 for the sizing of thermal overload heaters for all safety related motor operated valves.

4. Modifications required to replace undersized TOLs will be completed prior to the respective startup of Salem Units 1 and 2.

NRC FORM 366A (4-95)