ML19209B683

LER 79-070/03L-0:on 790921,potential Inaccuracy in Reactor Vessel Water Level Instrumentation Noted,Following Receipt of GE Svc Info Ltr 299.Plant Mods Written to Raise Initiation Setpoints & Operating Manual Revised

ML19209B683
Person / Time
Site:	Brunswick
Issue date:	10/03/1979
From:	Tollison A CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209B684	List: ML19209B683
References
LER-79-070-03L, LER-79-70-3L, NUDOCS 7910100316
Download: ML19209B683 (2)

Text

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LICENSEE EVENT REPORT CONTROL BLOCK: l 1

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lh (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 7 0 t 8 9 l N l C l "3 LICENSEE CODE E l Pl 1l@l 0 l 0 l -l 0 l 0 0l 0l 0 -l0l0l@l4l1l1l1l1l@l 14 15 LICENSE NUMBER 25 26 LICENSE TYPE JO l

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h O 2 l A review of the reactor vnsel water level instrumentation following the receipt of I O 3 l General Electric Service Information Letter No. 299 resulted in the identification of l ITTTI a potential inaccuracy which could occur under the unusual condition of a very high I

[T[Tl drywell temperature characterized by accident conditions. The effect of this in- I

[O_j_J l accuracy is acceptable from a safety stand ooint. but it could result in a reduction i O 7' I in redundancv of the initiating signals of some Emergency Core Cooling Systems and l 0 a i lead to some misinterpretation of acetal vessel level by the operator.

7 8 9 Technical SFEgifirag3gs 3.}4 S

6.' . 9a COMP. vAtvE CODE CODE SUSCODE COMPONEP '. ; ODE SUSCODE SU8 CODE R 8 l Il Blh Wh l A lh lI lN l S lT lR lU lh E h yh 9 10 12 18 20 7 1 13 19 SEQUENTIAL OCCURRENCE REPORT REVISION

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30 l-l 31 W32 TK N AC O O / NT M HOURS 22 S8 I FOR 8. SUPPL MANUF CTURER l33G lgl34Z lg l5Zlg 3 36 Z[@ 37 0l0l0l0l l Y lg 41 l42 Y lg l N lg l Y l 0 l 1 l 0 lg 40 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i O I Large increases'in drywell temperature, such as those that could occur during a pipe i 11 lii rupture in the drvwell, would cause the reference leg of the varwa. level indication s_]

m to heat up. As the reference leg temperaturee increase, its density will decrease i ITTTI I causing a decreasing D/P. This decreasing D/P would register as an increasing vessel l W l 8level on the D/P cell indicator and the remote indication. (Continued) 7 9 PO ST  % POWER OTHER STATUS dis O RY DISCOVERY DESCRIPTION l,,1_j_j dh l 0 l 6 l 3 lhl NA l l45Dlhl Vendor Notification l 7 8 1 12 11 44 46 80 RELEASED OF RELEASE AMOUNTOF ACTIVITY LOCATION OF RELEASE 1 6 h hl NA l l NA l PERSONNEL EXPOS ES NUMBER TYPE L ;j 1 7 l0 0 0lhb;_jhl DESCRIPTION NA J 01 l PERSONNEL INJURIES NUMBFR DESCRIPTION R l 80l 7 9 0 O!hl NA 11 12 /V A

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LER CONTINUATION -- RO# 1-79-070 Facility: BSEP Unit No.1 Event Date: 9-21-79 Technical Specifications 3.3.3, 6.9.1.9a CAUSE DESCRIPTION AND CORRECTIVE ACTION:

The initiation setpoints and accident conditions were evaluated and plant modifications were written to raise the setpoints to assure proper functioning under worst case drywell conditions. Revisions were made to the Operating Manual to reflect the new setpoints, warn the operator of the potential sensi-tivity of the yarway level indicators to drywell temperature, and provide additional guidance on the initiation and securing of ECCS equipment.

While review of plant design and performance is a continuing evaluation, this is considered an isolated event and no further action is required.

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