05000325/LER-1985-001, :on 850103,calibr of Reactor Vessel Shroud Level Instruments 1(2)-B21-LTM-N036-1 & N037-1,did Not Meet Design Intent.Caused by Inconsistency in Data Sheets. Instruments Properly Calibr

:on 850103,calibr of Reactor Vessel Shroud Level Instruments 1(2)-B21-LTM-N036-1 & N037-1,did Not Meet Design Intent.Caused by Inconsistency in Data Sheets. Instruments Properly Calibr

ML20105B667
Person / Time
Site:	Brunswick
Issue date:	02/01/1985
From:	Dietz C, Pastva M CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
BSEP-85-0102, BSEP-85-102, LER-85-001, LER-85-1, NUDOCS 8502070485
Download: ML20105B667 (3)

LER-1985-001, on 850103,calibr of Reactor Vessel Shroud Level Instruments 1(2)-B21-LTM-N036-1 & N037-1,did Not Meet Design Intent.Caused by Inconsistency in Data Sheets. Instruments Properly Calibr

Event date:
Report date:
3251985001R00 - NRC Website

text

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Brunswick Steam Electric Plant Unit 1 o l5 l 0 l0 l 0131215 1l0Fl0l2 TITLE let Inadeauate Calibration of the Units I and 2 Reactor Shroud' Level Instrumentation EVENT OATS (Si LER NUneSER (m REPORT DATE 17)

OTHER F ACILITIES INVOLVED 18)

MONTH Day YEAR PAQUTV NAdts DOCKET NUMSERis)

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NAME TELEPHONE NUMBER AREA CODE M. J. Pastva, Jr., Regulatory Technician 91 1 9 4 l5l7 1 -l 2 l 3 1 l 5 1

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.se., H o On 01/03/85, a determination was made that the calibration of the Units 1 and 2 reacter veccci chroud level inctru=cnto, 1(2)-E21-LTM-NO36-1 and NO37-1, did not meet the design intent. This was based on a discovered inconsistency,

between the plant instrument calibration procedure for the subject instruments and the Instrument Data Sheet of the instruments' manufacturer. Use of the subject calibration procedure resulted in the instruments providing a permissive to allow manual initiation of primary containment spray when vessel level has been restored above the technical specifications of >/= -53" reactor level following a loss of coolant accident. After correspondence with General Electric, the system designer, a determination was made that the design intent of the NO36-1 and NO37-1 is to prohibit a containment spray permissive on reactor level >/= -53".

Following a determination of the design intent of the NO36-1 and NO37-1 instruments, appropriate calibration procedure for the instruments was rewritten and the instruments were properly calibrated.

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==.,w awe s asiaw nn On January 3, 1985, a determination was made that the calibration method employed to establish the actuation setpoints of the Units l'and 2 reactor vessel shroud level inst'ruments resulted in failure to meet the design intent of the instruments. These instruments, 1(2)-B21-LTM-N036-1 and NO37-1, provide reactor shroud level permissive logic input to the primary containment spray mode of the unit Residual Heat Removal (RHR) System. The calibration method based the instruments' actuation setpoints as a function of the reset setpoints by utilizing an increasing input signal and verifying that containment spray could not be initiated prior to reaching >/= -53".

The calibration method was developed from an interpretation that the purpose of the instruments is to provide a permissive to initiate primary containment spray after a loss of coolant accident following restoration of reactor level above the technical specifications setpoint. The actual design intent is to prohibit containment spray prior to and below a setpoint, >/= -53".

The initial interpretation was based on the plant Final Safety Analysis Report and sheet 8, revision 1, of Instrument Data Sheet 234A9301RL in Volume V, Book 1, GEK-16654, of the instruments' Technical Manual, GEK-9693. Revision 1 to the sheet did not specify a direction for the setpoint.

However, revision 9 to the Instrument Datt Sheet specified the setpoint in the decreasing level direction.

Due to the instrument reset band inherent in the instruments, the capability

- existed to manually initiate primary containment spray'on a decreasing reactor level until -53.44" without use of the permissive interlock manual override.

Following correspondence with General Electric concerning the design intent of the NO36-1 and NO37-1, a determination was made that the instruments are designed to prohibit containment spray on decreasing reactor level at a value of >/=' -53".

Appropriate changes to the calibration procedures for the NO36-1 and NO37-1 instruments of both units were made, and the instruments were calibrated and returned to service.

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l CP&L Carolina Power & Light Company Brunswick Steam Electric Plant P. O. Box 10429 Southport, NC 28461-0429 February 1, 1985 FILE: B09-135100 SERIAL: BSEP/85-0102 NRC Document Control Desk U.S. Nuclear Regulatory Commission

. Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT UNIT 1 DOCKET NO. 50-325 LICENSE NO. DPR-71 LICENSEE EVENT REPORT 1-85-1 Gentlemen:

In accordance with Title 10 to the Code of Federal Regulations, the enclosed Licensee Event Report is submitted. This report fulfills the requirement for a written report within thirty (30) days of a reportable occurrence and is in

- accordance with the format set forth in NUREG-1022, September.1983.

Very-truly yours, bi

.C. R. Dietz, General Manager Brunswick Steam Electric Plant

'MJP/smp/LETSMP Enclosure cc:

Mr. R. C. DeYoung

'Mr.:J. P. O'Reilly.