ML18102B609

LER 97-012-00:on 970907,declared Reactor Coolant Loop 24 Overtemperature Differential Temp Inoperable Due to Differential Temp Being Lower than Acceptable.Returned Loop 23 Pressure Instrumentation to service.W/971003 Ltr

ML18102B609
Person / Time
Site:	Salem
Issue date:	10/03/1997
From:	Bakken A, Duca P Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-97-012-03, LER-97-12-3, LR-N970653, NUDOCS 9710150004
Download: ML18102B609 (5)

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• Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038-0236 Nuclear Business Unit OCT 3 1997 LR-N970653 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 LER 311/97-012-00 SALEM GENERATING STATION - UNIT 2 FACILITY OPERATING LICENSE NO. DPR-75 DOCKET NO. 50-311 Gentlemen:

This Licensee Event Report entitled ~Entry into Technical Spec~fication 3.0.3 Due to the Inoperability of Two Overtemperature-Differential Temperature (OTDT) Channels" is being submitted pursuant to the requirements of the Code of Federal Regulations ****10CFR50. 73 (a) (2) (i) (B) ****.

Sincerely, A. C. Bakken General Manager Salem.Operations Attachment PJD/tcp c Distribution LER File 3.7

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9710150004 971003 PDR ADOCK 05000311 S PDR 11111111111111111111111111111111

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llll llll The power is in your hands.

95-2168 REV. 6/94

NRCFORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED 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 UCENSEE EVENT REPORT (LER) LICENSING PROCESS AND FED BACK TO INDUSTRY. FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORM/.*T!ON ANO RECORDS MANAGEMENT BRANCH (T~ F33). U.S. ..UCLEAR (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 NAllE (1) DOCKET NUllBER (2) PAGE (3)

SALEM UNIT2 05000311 1 OF4 TITLE (4)

Entry into Technical S&ecification 3.0.3 Due to the lnoperability of Two Overtemperature-Differential Temperature (OTDT) hannels.

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

MONTH DAY YEAR YEAR I SEQUENT<AI.

NUMB Er~

lREVISION NUMBER MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 9 7 97 97 -- 012 - 00 10 03 97 FACILITY NAME DOCKET NUMBER OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more) (11)

MODE (9) 1 20.2201(b) 20.2203(a)(2)(v) x 50. 73(a)(2)(i)(B) 50. 73(a)(2)(viii)

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

LEVEL (10) 45% 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)

Philip J. Duca Jr., Salem Licensing Engineer (609) 339-2381 COMPLETE ONE LIN~ FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANµFACTURER REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE TONPRDS TONPRDS IYES SUPPLEMENTAL REPORT EXPECTED (14)

(If yes, complete EXPECTED SUBMISS!ON DATE).

IXINO EXPECTED SUBMISSION DATE (15)

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

On September 7, 1997 Reactor Coolant Loop 24 Overtemperature Differential Temperature (OTDT) was declared inoperable due to differential temperature being lower than acceptable. Loop 23 protection circuit was already inoperable in

.support of ongoing mairitenance work. Thus two channels of OTDT were inoperable, requiring entry into Technical Specification 3.0.3 at 0750. The maintenance work was terminated, Loop 23 OTDT was returned to an operable state and Technical Spec:..fication 3.0.3 *was *exited at 0840. The unac:ceptable differential temperature was cause.:. by a change in 24 Loop hot leg temperature (T-1-iot) streaming profile from the previous cycle, and the conservatively set NIS indication. The expected differential tempera tu.re was based on last cycle's streaming profile (the only information available) which caused the differential temperature to appear low. Corrective action included a check of the instrumentation calibration, collection of data to determine the new streaming profile and rescaling of Loop 24 instrumentation to reflect the current cycle streaming profile.

This event is reporta0le per 10CFR50.73(a) (2) (i) (B) , a condition prohibitE:;d by the plant's Technical SJ:.ecifications.

NRC FORM 366 (4-95)

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

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION .

FACILITY NAMEJ_ } --------n-D_O_C_K_ET_N_U_M_B_E_R_,(.__2..._)i1---~L_E_R_N_U_M_B_E_R--r-(6--')--1 t--_P_A_G_E~(3~)-_, 1 YEAR I SEQUENTIAL NUMBER I REVISION NUl\lllER SALEM UNIT 2 05000311 97 -- 012 - 00 2 OF 4 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

PLANT AND SYSTEM IDENTIFICATION Westinghouse - Pressurized Water Reactor Temperature Monitoring System {IM/-}

Nuclear Instrumentatior1 System { IG/-}

Reactor Coolant System {AB/-}

• Energy Industry Ider.tification System (EIIS) codes and component function identifier codes appear as {SS/CC}

IDENTIFICATION OF OCCURRENCE Entry into Technical Specification 3.0.3. due to the inoperability of two channels of Overtempera1Dre Differential Temperature instrumentation.

CONDITIONS PRIOR TO oc:URRENCE At the time of the occu:.~rence Salem Unit 2 was in Mode 1 at 45% reactor power.

DESCRIPTION OF OCCURRENCE On September 7, 1997 the Unit 2 Reactor Operator (RO) noted, during a channel check, that overtemperat.ure Differential Temperature (OTDT) actual Differential Temperature indication [IM/TI} on Reactor Coolant Loop 24 was out of the acceptable range when co~pared to a calculated comparison value for differential temperature (2.5 degrees low compared to + or - 2.0 degrees). As a result, Loop 24 OTDT was declared i_noperable. Differential temperatures in the other thr.ee loops were within the acceptable range. Since the Loop 23 protection circuit was already inoperable (bis tables placed in the tripped position) in support of ongoing maintenance work on Loop 23 pressurizer level instrumentation {AB/LT} ,

two channels of OTDT were inoperable. Technical Specification 3.3.1.1 requires a minimum of three channels operable for OTDT (Item 7 of Table 3. 3-1) . Since action statements for inoperable channels do not address inoperability of two

( 2) or more channels, Technical Specification 3. 0. 3 was entered at 07 5 0. The maintenance work was ~Ar~inated, Loop 23 protection circuit was returned to an operable state, the bi- ~ables were returned to the untripped position, Loop 23 OTDT was declared operable and Technical Specification 3.0.3 was exited at 0840.

The calculated compari3on differential temperature is dependent on average indicated reactor powec (NIS) {IG/JI} and expected full power differential temperature. NIS was conservatively reading 47% as compared to 45% power determined using a calorimetric calculation. Differential temperature compared to a comparison value tased on the calorimetric reactor power (45%) was within the acceptable range. ~fter consultation with Reactor Engineering, NIS was adjusted downward to br.i~g indicated power closer to power as determined by NRC FORM 366A (4*95)

(4-95) -

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NRC FORM 366A LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION IF============'==================~~===============;;==::==:~=="'====~========n=======================tr====';:=::'=-~======

FACILITY NAME (1j_ DOCKET NUMBER (2) LER NUMBER (6) PAGE@l.__

YEAR I SEQUENTIAL NUMBER I REVISION NUMBER SALEM UNIT 2 05000311 97 -- 12 00 3 OF 4 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) calorimetric calculation. This resulted in an acceptable Loop 24 indicated OTDT and the channel was returr,ed to an operable status.

This event is reportable per 10CFR.73(a) (2) (i) (B), a condition prohibited b~ the plant's Technical Specifications.

ANALYSIS OF OCCURRENCE Loop 24 Differential Temperature when compared to the calculated comparison value read low by greater than the 2 degrees allowable. The other three loops were within the accept~Jle range. Prior to the event, power as indicated on the NIS instrumentation was reading 47% while calorimetric calculated power was 45%.

The NIS was intentionally not adjusted downward to agree with the calorimetric value to ensure that NIS was indicating conservatively. This is in accordance with Salem's response to Westinghouse Technical Bulletin ESBU-TB-92-14-Rl. This ensures that the overpower trip would occur conservatively in the event of a tran~ient. The conservatism is necessary due to potential de-calibration effEcts at lower power levels and is typically maintained until adjustments are performed above 70% power in accordance with Technical Specifications and procedural requirements.

A calorimetric power calculation was perform~d shortly after the event and the NIS was adjusted downward by 1% after concurrence by Reactor Engineering in accordance with Salem's response to Westinghouse Technicai Bulletin ESBU-TB 14-Rl. Since the other three loops were within acceptable limits, it appeared that Loop 24 temperature instrumentation could be out of calibration low. A check of the 24.Loop temperature instrumentation showed the instrument loop to be accurate.*

"State point" data is ~~pically collected near 100% power to allow adjustment of the reactor protection system to the specific characteristics of the current cycle conditions. "Stat~ point" data taken on 9/21/97 at 90% power showed Loop 24 T-hot streaming profile to be different from the previous cycle. Collection of the data allowed Reactor Engineering to identify the change in T-hot streaming. The change in streaming profile resulted in the reference full power differential temperatun' being higher than it should have been and the actual differential temperature appearing lower than it should have been in relation to the calculated comparison differential temperature. Loop 24 values were then rescaled to reflect th* new full power differential temperature based on the exis.:ing streaming prc"...i__:_e. Loop 24 differential temperature was within the acceptable range subsequent to the rescaling.

PRIOR SIMILAR OCCURRENCES No similar occurrences could be found.

NRC FORM 366A (4-95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION

• (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION 11=========================~-*----==============;r==================n=====================;r=====~========~I FACILITY NA~ E .. \' )--------~~-D_O....;C;_K_ET __ N_U_M_B_E_R___,_(2....<.)-ll----L.--E_R_N;_U_M_B_E...:..R---;.(6-')'-----ll---P-A_G_E____,,(3-')'----1I YEAR I SEQUENTIAL NUMBER I RElllSION NUM3ER SALEM UNIT 2 05000311 97 -- 12 00 4 OF 4 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

CAUSE OF OCCURRENCE The cause of Loop 24 differential temperature appearing to be outside the acceptable range was the change in the T-hot streaming profile. The calculated comparison value was based on the expected full power differential temperature which assumed the streaming profile from the previous cycle. This was the only streaming information available at the time. This resulted in the expected full power differential temperature being overstated high and the Loop 24 differential temperature being observed low.

The conservative setting of NIS in relation to calorimetric power, at 45% power, resulting in the unsatisfactory differential channel check, provided an early indication of the T-hot streaming profile change and prompted the 90% state point data collection 3nd subsequent rescaling of 24 Loop instrumentation.

ASSESSMENT OF SAFETY c:.:.NSEQUENCES AND POTENTIAL IMPLICATIONS This event had no saie!ty consequences or potential implications. NIS was conservatively set abov~ the calorimetric value of 45% power. Two of the total of four OTDT channels will trip the reactor. Three of the four channels passed the channel check. At tb.e time of the event one of these channels was already in the safe condition (tripped) to support ongoing maintenance. Even if one of the two remaining operable *:::hannels failed, the logic would have responded to an actual condition and performed its safety function.

Baserl on the above, the Health and Safety of the public was not affected.

CORRECTIVE ACTIONS (1) Immediate corrective actions included: return of the Loop 23 pressure instrumentation to service, which allowed exiting Technical Specification 3.0.3; performance of a calorimetric calculation; and adjustment of the NIS downward 1%, which returned 24 Loop Differential Temperature to within acceptable limits.

(2) A work order was written to check Loop 24 Differential Temperature calibration. This effort showed the instrument loop was in calibration.

(3) As the plant appr03 :~~d 90% power, state point data was collected. Ana~ysis of this data led to the discovery that the Loop 24 T-hot streaming had changed.

Loop 24 values were then rescaled to reflect the new full power differential temperature based on the existing streaming profile.

NRC FORM 366A (4-95)

C FORM 366A (4-95)