05000458/LER-1990-028, :on 900930,RPS Actuation Occurred on High Level Scram Disharge Vol

:on 900930,RPS Actuation Occurred on High Level Scram Disharge Vol

ML20062D076
Person / Time
Site:	River Bend
Issue date:	10/30/1990
From:	England L, Odell W GULF STATES UTILITIES CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-028, LER-90-28, RBG-33923, NUDOCS 9011080314
Download: ML20062D076 (4)

LER-1990-028, on 900930,RPS Actuation Occurred on High Level Scram Disharge Vol

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation
4581990028R00 - NRC Website

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October. 30, 1990 RBG-33923 File Nos. G9.5, G9.25.1.3 U.S. Nuclear Regulatory Ccanission Document Control Desk Washington, D.C.

20555 Gentlenent River Bend Station - Unit 1 Docket No. 50-458 Please find enclosed Licensee Event Report No.90-028 for River Bend Station - Unit 1.

cThis report 'is being subnitted -

pursuant to 10CFR50.73.

Since 1,

W. H. Odell Manager-Oversight River Bond Nuclear Group cc U.S. Nuclear Regulatory Cmmission 611 Ryan Plaza Drive, suite 1000 Arlington, TX 76011-NRC Desident Inspector P.O. Box 1051 St. Francisville, IA 70775 INPO Records Center 1100 Circle 75 Parkway-Atlanta, GA 30339-3064L Mr. C. R. Oberg Public Utility Cartnission:of _'Ibxas 7800 Shoal Creek Blvd., Suite 400_ North.

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,1Ciu,, NAME n, OOC.8, uM.t. o, Am UIVER BEND STATION 0151010l0l41518 1 loFl 013 Reactor Protection System Actuation on High Level in the Scram Discharge Volume due to operator I:rror I

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At approximately 0427 on 09/30/90 with the unit in Operational Condition 4 (Cold Shutdown),

the reactor protection system (RPS) actuated on high water level in the scram discharge volume (SDV).

All control rods were inserted previously and no additional rod motion occurred due to the RPS actuation.

The root

cause

of the RPS actuation was the failure of the operator to bypass the scram discharge vclume (SDV) high level trip.

This event is reportable pursuant to 10CFR50.73 (a) (2) (iv) as an engineered safety feature (ESP) actuation.

All licensed operators will receive on-shift training on this event.

In

addition, a

" CAUTION" - will be added to Abnormal Operating "rocedure, AOP 0001 (Reactor Scram)- to remind the operatc.rs that the-scram discharge volume will take longer to fill and thus reach the high level trip when the plant-is at reduced pressure and/or there is no control rod motion.

The control rods were fully inserted prior to this event.

No additional rod motion occurred as a

result of the unplanned RPS actuation, and the.'PS system responded as designed.

Therefore, this event did not ' dversely affect the health and safety of the public.

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i, LICENSEE EVENT REPORT (LER).

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wnac n.in muw on REPORTED CONDITION At approximately 0427 on 09/30/90 with the unit ~in Operational; Condition 4 (Cold shutdown),

the. reactor protection system' (RPS)

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(*JE*)

actuated.on_

high water level in'the_ scram discharge volume (SDV).

All control rods were inserted previously and.no : additional rod motion occurred due to the RPS actuation.- The root cause of the

{

RPS actuation was the failure of the operator to bypass the ;SDV. high level trip.

This-' event is reportable pursuant to 10CFR50.73 (a)-(2) (iv)-

as an engineered safety fehture-(ESP) actuation.

INVESTIGATION f

on September 30, 1990, the reactor mode ~ switch

_ as in._the

" refuel"-

w position to allow. surveillance. testing of the! nuclear' instruments.?

With the surveillance testing completed, the; reactor mode --switch was required to be placed-in the

" shutdown" ' position.

At 0426=the at-the-controls (ATC). operator placed the mode switch in the

" shutdown" position, which in turn caused!a reactor protection system c

(RPS) actuation.

This RPS actuation was expected in response-to the i

preplanned placement of the mode switch in the " shutdown'.' position and thus is not reportable; however, a later RPS_ actuation. occurred due:to the failure of the ATC operatar to bypass the.SDVLhigh' level l trip.

This RPS actuation is, reportable p2rsuant_to 10CFR50. 73.

Following the expected RPS actuation,-the ATC operator. verified _ that the scram pilot solenoid valve statusz lights (*IL*)c had de-energized, but failed to review" Abnormal Operating-Procedure, AOP.-0001

(" Reactor

[

- Scram")

for subsequent operator' actions.-

.The ATC operator-then 4

noticed that the "CRD Scram Disch-Vol.High Water ~ Level"._ alarm

(*LA*)

i did not actuate.

'When the plant ~is' shutdown, _the SDV requires _more time to fill up than it'does.following control rod movement at : normal, I

l operating pressure.

At this point,'without placing-thec"CRD Scram

- i Disch Vol High Water Level Bypass" switches;in the " bypass"_ position,-

he, reset the;RPS actuation..At approximately.0427 the SDV_.high-water level trip occurred

• and caused the second RPS actuation.

This;

- l I

actuation was.not a'

part of' a preplanned _ activity!.and thus51s L

reportable under 10CFR50.73 as an ESF actuation.

At the' direction - of 4

l the-Shift-Supervisor, the ATC operator reviewed AOP-0001:and properly.

- reset the RPS actuation.

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A review ~ of previousl'y submitted LERs. revealed a

similar event?

j l

reported. in LER-85-002'.

In LER

'85- 002, three RPS actuations are 1

L described.

The first,and third RPS actuations were due to' inadvertent

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noise spikes; during an-inspection..of the main steam.line radiation monitors which tripped:RPS channel B coupled with RPS channel A'~being in a

manually tripped condition to perform the calibration.

The second actuation was due to high level in the SDV.

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CORRECTIVE ACTION

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l After the RPS actuation was reset, the Shift Supervisor' stopped all work in the main control room - and-briefed all on-shift-licensed-operators on this event..

He emphasized ~the need'to maintain control and the use of procedures.'regardless "of theDcurrent: Operational Condition.

Once he was satisfied that all.of the ' operators present-3

- understood the severity of-the: situation;he authorized the restart of work activities.-

5 As-further corrective action'a " CAUTION" will be. added to-AOP-0001,

" Reactor Scram".

The " CAUTION" will be used.to remind the operators" i

'that at reduced reactor pressure;and/or with no-control l rod motion-that the SDV will take longer to fill and reach the high level trip.

In addition, all licensed operators will receive on-shift 1 training on this event by November 6, 1990.

SAFETY ASSESSMENT

The control rods were fully ' inserted prior to : this'. event.

No i

additional rod motion occurred.as' a result.of -

the'.= unplanned RPS actuation, and the RPS system responded as. designed.- Therefore,.this' l

event did not adversely affect the health'and safetyfof'the public..

NOTE:

Energy Industry Identification: System Codes are identified'lin?

j the text as (*XX*).

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