05000266/LER-1997-026, :on 970521,discovered TS Violation of Operability Requirement of MSL Isolation.Caused by Inadequate Consideration for Operability of All Required Functions.Verified Low RCS Sys Average Temp

:on 970521,discovered TS Violation of Operability Requirement of MSL Isolation.Caused by Inadequate Consideration for Operability of All Required Functions.Verified Low RCS Sys Average Temp

ML20141C266
Person / Time
Site:	Point Beach
Issue date:	06/19/1997
From:	Castell C WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20141C260	List: 05000266/LER-1997-026, :on 970521,discovered TS Violation of Operability Requirement of MSL Isolation.Caused by Inadequate Consideration for Operability of All Required Functions.Verified Low RCS Sys Average Temp
References
LER-97-026, LER-97-26, NUDOCS 9706250078
Download: ML20141C266 (5)

LER-1997-026, on 970521,discovered TS Violation of Operability Requirement of MSL Isolation.Caused by Inadequate Consideration for Operability of All Required Functions.Verified Low RCS Sys Average Temp

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2661997026R00 - NRC Website

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3160-0104 i

(4-95)

EXPlRES 04/30/98 l

ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THl3 (NFORMATION COLLECTION REQUEST: 50.0 HRS.

REPORTED LESSONS LEARNED ARE INCORPORATED LICENSEE EVENT REPORT (LER)

INTO THE LICENSING PROCESS AND FED BACK TO INDUSTRY.

FORWARD COMMENTS REGARDING BUROEN ESTIMATE TO THE INFORMATION AND (See reverse for required number of RECORDS MANAGEMENT BRANCH {T-6 F33),

U.S.

digits / characters for each block)

NUCLEAR REGULATORY COMMISSloN, WASHINGTON.

DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT 1

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FACILITY NAME (1)

DOCKET NUMBER (2)

PAGE (3) lPointBeachNuclearPlant, Unit 1 05000266 1 OF 5 TITLE (4)

Technical Specification Violation of Operability Requirement for Main Steam Line Isolation EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACillTIES INVOLVED (8)

IYEAR SEQUEN TIAL REVISION FACluTY NAME DOCKET PeUMBER MONTH DAY YEAR NUMBER NUMBER MONTH DAY YEAR Unit 2 05000301 l

l l

FACILITY NAME DOCKET NUMBER i

l 05 21 l 97 l 97 026 --

00 06 19 97 05000 l OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR B: (Check one or more) (11)

MODE (9)

N l 20.220i te) 20.2203iaH2Hv8 X

50.73(aH2)o) 50.73(aH2Hvm)

POWER 20.2203(aH1) 20.2203(aH3)h) 50.73(aH2Hii) 50.73(aH2)(x)

LEVEL (101 000 20.2203(aH2H )

20 2203(aH3Hio 50.73(aH2Hm) 73.7i 20.2203(aH2Hn) 20.2203(aH41 50,73(aH2Hrv)

OTHER 20.2203(aH2Hm) 50.36(cH1)

50. 73(aH2Hv)

Specify in Abstract below l

20.2203(a H 2)hv)

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50.73(aH2Hvn) or in NRC Form 366A LICENSEONTACT FOR THIS LER 612)

IWAME TELEPHONE NUMBER (include Area Code)

Curtis A. Castell (414) 221-2019 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE

SYSTEM COMPONENT MANUFACTURER REPOR T ABLE

CAUSE

SYSTE COMPONENT MANUFACTURER REPORTABLE TO NPROS M

TO NPRDS SUPPLEMENTAL REPORT EXPECTED (14) l EXPECTED MONTH I DAY YEAR i

l YES SUBMISSION tif yes, complete EXPECTED SU9 MISSION DATE).

X NO DATE (16)

ABSMACT q$to 1400 spaces, te., approximately 16 single-spaced typewntten lines) (16) i On May 21, 1997, while PBNP Unit I was in a cold shutdown condition and Unit 2 was in a defueled condition, it was discovered that operability of the reactor coolant system l

average temperature instrumentation input to the main steam line isolation function was not being maintained in accordance with Technical Specification operability requirements, I

It has been concluded that the Technical Specification was violated each time either ur.it was above cold shutdown conditions with scaling resistors in place and the low reactor coolant system average temperature input to main steam line was not in the trip condition. This condition was caused by insufficient or inadequate consideration for operability of all required functions that rely on this input. The low reactor coolant system average temperature input to main steam line will be verified to be in the trip condition prior to leaving the cold shutdown condition when the scaling resistors are in place. It has been concluded that this situation did not diminish the safety of the public, plant personnel, or integrity of safety barriers place at PBNP at any time.

NRC FORM 366 (4-95) 9706250078 970619 PDR ADOCK 05000266 l

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NR$; FOHM 366A U.S. NUCLEAR REGULATORV COMMISS60N (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILIIY NAME 11)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Point Beach Nuclear Plant, Unit'l 05000266 NUMBER NUMBER 2 OF 5 97 026 00 IEKI lit mort 8p0C013 f0 quired, U50 odditional Cops 0s of NHC form 366Al (11)

Event Description

l l

On May 21, 1997, while Point Beach Nuclear Plant (PBNP) Unit 1 was in a l

cold shutdown condition and Unit 2 was in a defueled condition, it was l

discovered that operability of the reactor coolant system average temperature instrumentation input to the main. steam line isolation l

function was not being maintained in accordance with Technical l

Specification Table 15.3.5-4 item 2.b operability requirements.

It has been standard practice at PBNP to install scaling resistors in the average temperature instrumentation to allow average temperature to be maintained on scale.

The scale on average temperature is 540 to 615 F.

The scaling l

resistors replace the function of the resistance temperature devices in the reactor coolant system.

The scaling resistors cause the reactor coolant system average temperature instrumentation to be maintained at about 570 F.

i l

The scaling resistors are normally installed after cold shutdown is established.

The resistors are normally removed at about 540 F.

Technical Specification Table 15.3.5-4 item 2.b provides operability requirements for main steam line isolation on hi steam flow coincident with low reactor coolant system average temperature and safety l

injection.

This Technical Specification for the low reactor coolant

)

i system average temperature input states that the affected unit must be placed in hot shutdown within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> if the operability requirement is not met.

Therefore, it has been concluded that the operability requirement for this input was violated, each time either unit was above cold shutdown conditions with the scaling resistors in place and the low reactor coolant system average temperature input to main steam line not in the trip condition.

The practice of installing the scaling resistors was instituted about 25 years ago to improve the configuration of the circuitry during long j

periods of shutdown by maintaining the circuitry consistent with its q

normal operating range.

1 WHC FORM 366A 14-96)

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NRC f0RM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

I TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER 16)

PAGE (3)

YEAR SEQUENTIAL REVISION l

Point Beach Nuclear Plant, Unit 1 05000266 NUMBER NUMBER 3OF5 l

97 026 00 TEXT tu mwe space is,equwea, use essitiones copies or nac form 366A) (1 15 l

Cause

This condition was caused by insufficient or inadequate consideration for operability of all required functions that rely on this input.

Corrective Actions

Appropria te procedure changes will be implemented to verify that the low reactor coolant system average temperature input to main steam line is placed in the trip condition prior to leaving the cold shutdown condition when the scaling resistors are in place.

This will ensure the Technical Specification operability requirements for the main steam line isolation on hi steam flow coincident with low reactor coolant system average temperature and safety injection wi11 be met.

A root cause evaluation is being completed.

Additional corrective actions

will be taken, as appropriate, from recommendations contained in the root cause evaluation.

RIportability:

This Licensee Event Report is being submitted in accordance with the requirements of 10 CFR 50.73 (a) (2) (i) (B), "Any operation or condition prohibited by the plant's Technical Specifications."

Component and System Description:

The main steam line isolation function causes a closure signal for the main steam isolation valves (MS-2017 and MS-2018).

The Technical Specifications provide the operability requirements for the inputs to this isolation function as follows:

(a) Hi Hi Steam Flow with Safety Injection, (b) Hi Steam Flow and Low Tavg with Safety Injection, (c) Hi Containment Pressure, and (d) Manual.

The condition described in this report caused the Hi Steam Flow and Low Tavg with Safety Injection isolation signal to be inoperable prior to removal of the scaling resistors.

The purpose of the steam line isolation function as described in the PBNP FSAR in section 14.2.5 states, "Each steam line has a fast closing isolation valve and a check valve.

These four valves prevent blowdown of more than one steam generator for any break location even if one valve fails to close."~,.

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

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

OOCKET NUMBER (2)

LER NUM8ER 16)

PAGE (3)

YEAR SEQUEN TIAL REVISION Point Beach Nuclear Plant, Unit 1 05000266 NUMBER NUMBER 4OF5 97 026 00 TEXT tir,nore space,s requaes. use assitenar coon,s of NRC forn; 366A) (17)

Sofety Assessment:

The main purpose of the main steam line isolation signal is to mitigate a steam line rupture or rapid cooldown of the reactor coolant system by closure of the main steam line isolation valves.

The Hi Hi Steam Flow with Safety Injection isolation function is intended to cause isolation for relatively high steam flow rates (4 x 10' lb/hr).

The Hi Steam Flow and Low Tavg with Safety Injection is intended to cause isolation for relatively low steam flow rates (0.66 x 10' lb/hr).

If a steam line rupture or rapid cooldown occurred during the time the scaling resistors were in place and the low Tavg input was not in trip, then manual steam line isolation may have been needed to prevent blowdown of both steam generators.

At lower initial reactor coolant system temperatures than used in the FSAR section 14.2.5 " Rupture of a Steam Pipe" analysis, which is based on an initial reactor coolant system temperature of 547 F, the cooldown and hence the reactivity insertion would be less.

This reduces the chances that a return to criticality could occur for this accident.

Even if a return to criticelity occurred it is likely that it would not be as severe as the limiting transients that have been analyzed and presented in the FSAR Chapter 14.

Therafore, the inoperability of Hi Steam Flow and Low Tavg with Safety Injection input to the steam line isolation function between hot and cold shutdown conditions did not diminish the safety of the public, plant personnel, or integrity of safety barriers in place at PBNP at any time.

System and Component Identifiers The Energy Industry Identification System component function identifier for each component / system referred to in this report are as follows:

Component / System Identifier Main Steam Isolation Valve ISV Main Steam System SB j

Reactor Coolant System AB

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High Pressure Safety injection System BQ i

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NRC FORM 368A U.S. NUCLEAR LEGULAVOR7 COMMISSION I

(4-9 5)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER 16) l PAGE 13)

YEAR SEQUENTIAL REVISION l Point Beach Nuclear Plant, Unit 1 05000266 NUMBER NUMBER l 5 OF 5 97 026 00 l

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Similar occurrences:

l A search of previously submitted licensee event reports similar to this situation for PBNP was conducted.

The specific criterion used was based on a search for licensee event reports that were submitted due to reconfiguration of instrumentation not being adequately evaluated which resulted in a Technical Specification violation.

No similar occurrences were identified.

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