ML20235K974
| ML20235K974 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 09/22/1987 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8710050298 | |
| Download: ML20235K974 (2) | |
Text
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4 DUKE POWER GOMPANY P.O. BOX 33180 CHARLOTTE. N.C. 28242 HALH.TUGKER TELEPHOltE war renament
(?O4) 073-4531 NfM1 LEAR PhursUUTION l
September 22, 1987 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555
Subject:
Catawba Nuclear Station, Unit 2 Docket No. 50-414 Gentlemen:
o Pursuant to Technical Specification 3.4.9.3, please find attached a Special Report concerning the lifting of Catawba Unit 2 pressurizer PORV in low pressure mode.
Very truly yours,
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Hal B. Tucker JGT/130/sbn Attachment xc:
Dr. J, Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. P. K. Van Doorn NRC Resident Inspector Catawba Nuclear Station S
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. ;. 4 8710050298 070922 PDR ADOCK 05000414 s
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SPECIAL REPORT i
' OPENING OF CATAWBA' UNIT 2 PRESSURIZER PORV I
l Problem:
At 0610' hours on August'23, 1987, 2NC-34 (pressurizer PORV) opened while in'the Low Pressure Mode (the lift setpoint for PORV's in'the Low Pressure mode is 400 psig).. Plant conditions at the time.of this' occurrence were as follows:
(1)-
Mode 5 (Cold Shutdown) with the FillinE and Venting the' Reactor Coolant (NC) l System procedure in. progress; (2) NC system pressure was being increased to start l
NC pumps; and'(3) NC pressure was 388 psig (per Operator Aid' Computer (OAC). point-A0839) when 2NC-34 opened.
Background:
.NC system wide range.(W/R)' pressure instruments (2NCPT 5120 and 2NCPT 5140) are used to monitor Pressure while in Mode 5. 'The string error associated with each instrument is 1.35%. 'This is' equivalent to 140.5 psig when multiplied by the L
range of instrument-(0-3000 psig). All of this error is applied to.the Control' l'
Room indication as opposed to the PORV circuit which has less error. This could cause the pressure that the PORV senses to be different from the. pressure
. indicated in the Control Room.
Corrective Action:
At'the' time of the transient, NC pressure was immediately reduced to 325 psig by increasing letdown flow'and 2NC-34 closed.
I In the future, Operations procedures will be changed to Monitor both channels of NC pressure..while in Low Pressure Mode and use the most conservative value (highest pressure) computer points A0839 for NCPT 5120 and A0719 for NCPT 5140.
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.Also, an' evaluation will be conducted to determine if NC pressure should normally be limited to a value less than 360'psig during solid plant operations except for certain activities such as increasing NC pressure to achieve adequate seal l
1eakoff flow for NC pump starts.
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