ML20029C124

From kanterella
Jump to navigation Jump to search
LER 91-005-01:on 910131,1/2 B Standby Gas Treatment Sys Autostart During RPS B Power Swap Due to an Inadequate Procedure.Nso Reset 1/2 Scram & 1/2 Groups II & III isolations.W/910306 Ltr
ML20029C124
Person / Time
Site: Quad Cities Constellation icon.png
Issue date: 03/08/1991
From: Bax R, David Harmon
COMMONWEALTH EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-005, LER-91-5, RLB-91-073, RLB-91-73, NUDOCS 9103260175
Download: ML20029C124 (6)
v • d • e


Text

. . _ _ _ . . _ . _ . - .

^

Conimonw;alth Edison - '!

5 ( ./ f '::- .

ouad Citts Nuciear Power Stttion _)b .  :

W*  !

. ),

ryj 22710 206 Avenue North -

Cordova, lihnots 61242-9740,

'- ( Telephone 309/654 2241.

RLB-91-073

.l--

r

' March 6, 1991-U. S. Nuclear Regulatory Commission.

Document Control. Desk ~~

Hashington,.DC120555=

e

Reference:

-Quad lC) ties Nuclear Power Station Docket Number 50-254, DPR-29, Unit One i k Enclosed is Licensee Event, Report (LER)91-005, kevision 01, for Quad C1 ties Nuclear-Power Station.

b Respectfully, .

COMMONHEALT!i EDISON ' COMPANY (QUAD CITIES NUCLEAR POWER STATION

.g y

R. L. Bat -

Station Manager

RLB/TB/kas-4 l-Enclosure

.cc: R. Stols. /

i. T. Taylor /

, .INPO Records Center NRC Region III.

rc

.STMGR 55 9103260175 910308 -

gygg '[T y D) d' PDR. ADOCK 05000254

.g PDR

Y .: t.ICENSEE EVENT REPOR7-(LER)

F e Rev 2 1 Facility Name (1) Docket Number (3) ~ _f.ARIL f 31 ad cities

  • Unit One 01 El 01 01 01 21 51 4 1 of 0 5 Title'(4) 1/2 B SBGT Unernected Autostart Durino RPS B Power Swan Due To An Inadeauate Proeggure Event Date fE1 LER Number (61 Recort Date (7) Other racilities Involved _fB1 Month Day Year Year /,/p/ sequential ,/p,/ / Revision Month. Day Year Facility Names Docket Numbarfs)

/// Number /// Number 01 51 of 01 01 I l

~~~ ~~

01 1 31 1 91 1 91=1 0 1 0-l 5 0l1 013 ol 8 91 1 01 El 01 01_01 1 1 OPERATING' l.C.bigk one or more of the followina) i111 1 20.402(b) __ 20.405(c) X., 50.73(a)(2)(iv) 73.71(b)

POWER ,,, 20.405(a)(1)(1) 50.36(c)(1) _ 50.73(a)(2)(v) _ 73.71(c)

LEVEL 20.405(a)(1)(11) __ 50.36(c)(2) __ 50.73(a)(2)(vii) Other (specify f101 0! 01 0 20.4!)S(a)(1)(iii) 50.73(a)(2)(1) _, 50.73(a)(2)(v111)(A) in Abstract

///////////////,/////////// 20.405(a)(1)(iv) 50.73(a)(2)(li) _ 50.73(a)(2)(viii)(B) bel a and in

///////////////'j/////////// 20.405(a)(1)(v) _ 50.73(a)(2)(111) ,__ 50.73(a)(2)(x) Text)

LICENSEE CONTACT FOR THIS LER f121

.Name TELEPHONE NUMBER AREA CODE David Harmon.-Technical Staff Enaineer Ext. 2116 3 10l9 61SI41-l2121411 COMPLETE ONE LINE FOR EACH COM T FAILURE DESCRIBED IN THIS REPORT (131 CAusE SYSTEM COMPONENT MANuFAC- REPORTABLE CAuSE SYSTEM COMPONENT. MANurAC- REPORTABLE

///%/ f TURER TO NPRDS TURER TO NPROS ^/

I I I I I i 1 1 1 1 I I i 1 //

j, l 1 I I I i 1 '/ 1 I I I I I I //

SUPPLEMENTAL REPORT EXPECTED f141 Expected Month l Day l Year submission lyes fif ves. comolete EXPECTED SUBMISSION DATE) X l No l ll ll A8sTRACT (Limit to 1400 spaces i.e. approximately fif teen single-space typewritten lines) (16)

ABSTRACT:

'On January 31, 1991, at 2013 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.659465e-4 months <br />, Unit One was in SHUTDOHN mode and Unit Two was

'in_RUN mode at 94 percent!of rated core thermal power. Operating personnel .

performed a Reactor Protection System (RPS) power supply transfer. As expected, it caused a 1/2 scram and-1/2 Group II and III isolations, which resulted in the 1/2 B Standby Gas Treatment System (SBGTS) autostart timer starting.

The NSO reset the 1/2 scram. 1/2_B SBGTS unexpectedly autostarted before the NSO l reset the-1/2 group-II and III isolt.tions. The NSO secured 1/2 B-SBGTS and L operability-tested 1/2 A SBGTS.

l An Emergency Notification System (ENS) phone notification was completed at 0001

. hours on February 1, 1991, under 10CFR50.72(b)(2)(11).

'Both units entered a 7 day LCO intil Operating personnel verified the accuracy of-the.1/2 8 SBGTS 25 second autostart timer. Operating personnel determined-that RPS and SBGTS functioned as-designed.

The cause of the event was-that the procedure failed to specify that the NSO must reset the 1/2 group II and III isolations within.25 seconds of loss of power to RPS in order to prevent autostart of 1/2 B SBGTS. A procedure correction was implemented.

jf 3408H

./" -

l' LICENSELLyENT REPORT f LtRi TEX 7 C0_NTINUATION Form Rev 2.0_

DOCKET NUMBER (2) LER NUMBER f61 Pace (31 p . FACILITY NAME (1)

Year /// sequential l /// Revision p/,/j/ Number j/// Number

_00Ad Cities Unit One 0 1 5 1 0 1 0 1 0 1 21 El 4 9l 1 010l $ - 0l i el 2 0F 01 5 TEXT Energy Industry Identification system (Ells) codes are identified in the text as (Xx) i PLANT AND SYSTEM IDENTIFICATION:

General Electric - Boiling Water Reactor - 2511 MWt rated core thermal power.

EVENT IDENTIFICATION: 1/2 B SBGT Unexpected Autostart During RPS B Power Swap Due To An Inadequate Procedure A. CONDITIONS PRIOR TO EVENT:

Unit: One Event Date: January 31, 1991 Event Time: 2015 Reactor Mode: 1 Mode Name: SHUTDOWN Power Level: 00%

This report was initiated by Deviation Report D-4-1-91-025 SHUTDOWN Mode (1) - In this position, a reactor scram is initiated, power to the control rod drives is removed, and the reactor protection trip systems have been deenergized for 10 seconds prior to permissive for manual reset.

B.. DESCRIPTION OF EVENT:

On January 31, 1991, at 2013 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.659465e-4 months <br />, Unit One was in SHUTDOWN mode for scheduled refueling outage QlRil and Unit Two was in RUN mode at 94 percent of rated core thermal power. Operating (0P) personnel perfornied procedure QOP 7000-1, Reactor Protection System [JC) (RPS) Motor [MO) Generator [ GEN) (MG) Sets. Immediately thereafter, the 1/2 B train of Standby Gas Treatment Sytem (BH] (SBGTS), which was in STANDBY mode, unexpectedly autostarted.

Prior to this, at approximately 2010 hours0.0233 days <br />0.558 hours <br />0.00332 weeks <br />7.64805e-4 months <br /> on January 31, 1991, OP personnel began performing QOP 7000-1. This procedure instructs OP personnel on how to energize, de-energize, and switch RPS power supplies [UJX) between normal and reserve power.

At 2013:31 hours, an Equipment Operator (EO) switched the power supply to RPS Channel B (RPS B) from reserve to normal power. This power supply switching caused an expected momentary loss of power to RPS B which de-energized Primary Containment Isolation (PCI) Group II B relay (RLY) logic. This logic de-energization, in turn, started the 1/2 B SBGTS 25 second autostart timer CTMR). At the same time, the Unit One Nuclear Station Operator (NS0) received a 1/2 scram signal on the 901-5 panel, and PCI 1/2 Group II and III isolation signals on the 901-5 panel. All of these signals normally occur on de-energization of an RPS bus [BU). The NSO restored normal power to RPS B ana reset the 1/2 scram at 2013:32 hours.

1/2 A SBGTL was in PRIMARY at the start of the event and remained nonactive during

/ the event as designed. At approximately 2013:56 hours, 1/2 B SBGTS autostarted unexpectedly. Review of the logic later showed that 1/2 A SBGTS did not receive an autostart signal, and that 1/2 B SBGTS autostarted as designed (when the 25 second autostart timer timed-out.)

1 3408H

4 LICENSEE EVENT REPORT fLER1 TEX 7 CONTINUATION _ EQIhLRtwM FACILITY NAME (1) DOCKET NUMBER (3) L E R NUME E'2 ( 6 )

Pace (1) j Year p//

/ sequential' /// Revtsion

- /j/j/ _ N_ umber

,/j/j/ Numbgr._

Ouad Cities Unit One 0l51010l0 1 21 El 4 9l 1 - 010 15 - 0l 1 01._3 0F 01 5 TEXT Energy Industry Identification system (E!!s) cooes are identified in the trixt as (XX)

At approximately 2014:00 hours, the NSO reset the 1/2 Group II and III isolations using the isolation reset switch, ISOL RESET, on the 901-5 panel. This also reset the 1/2 B SBGTS autostart signal and autostart timer.

At 2015 hours0.0233 days <br />0.56 hours <br />0.00333 weeks <br />7.667075e-4 months <br />, the NSO shut down 1/2 B SBGTS and returned it to STAND 0Y mode.

The Shift Engineer (SE) directed the NSO to perform procedure Q05 7500-S, SBGTS Monthly Operability Test, to verify operability of 1/2 A SBGTS. Technical Specifications (Tech Specs) section 3.7.B.1 requirec that one SBGTS train be demonstrated operable within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of finding the other train inoperable. This operability verification was intentionally conservative to the intent of Tecn Specs since 1/2 B SBGTS had not been declared inoperable. At 2215 hours0.0256 days <br />0.615 hours <br />0.00366 weeks <br />8.428075e-4 months <br />, the HSO began to perform the test, which takes a minimum cf 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> to complete.

At 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br />, the SE initiated a Deviation Report (DVR). Operating personnel continued to investigate the event due to uncertainty about the 1/2 B SBGTS autostart timer. The exact time at which 1/2 B SBGTS autostarted was not available on the computer.

An Emergency Notification System (ENS) phone notification was completed at 0001 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> on February 1, 1991, under 10CFR50.72(o)(2)(li).

At 0300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> on February 1, 1991, the SE declared 1/2 B SBGTS inoperable and initiated outage report QOS 7500-01, SBGTS One Circuit Operation Outage Report 7 Day Limitation. OP personnel were still uncertain about the 1/2 B SBGTS autostart timer. Both units entered a 7 day Limiting Condition for Operation (LCO) retroactive to 2013 hours0.0233 days <br />0.559 hours <br />0.00333 weeks <br />7.659465e-4 months <br /> on January 31, 1991.

At 1707 hours0.0198 days <br />0.474 hours <br />0.00282 weeks <br />6.495135e-4 months <br /> on February 1,1991, Operating personnel concluded that RPS and 1/2 B SBGTS had functioned as designed, and that the autostart occurred because the NSO did not reset the 1/2 Group II and III isolations within 25 seconds of the power supply switching. Because the procedure had been successfully performed prior to this event, they suspected that the autostart timer may have timed-out early. To test the accuracy of the 1/2 B SBGTS autostart timer, OP personnel decided to perform step 3 of QOS 7500-4, Standby Gas Auto Initiation and Reactor Building Ventilation Auto Isolation. This test would place both units in a 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> LCO per Tech Spec section 3.7.B.I.b-At 1723 hours0.0199 days <br />0.479 hours <br />0.00285 weeks <br />6.556015e-4 months <br />, OP personnel olaced both units in a 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> LCO and performed the test. They timed the 1/2 B SBGTS timer to actuate at 24.75 seconds, which is within accep;able tolerance limits.

OP personnel completed the test by 1725 hours0.02 days <br />0.479 hours <br />0.00285 weeks <br />6.563625e-4 months <br /> and concluded that RPS and SBGTS functione) as designed throughout the event. The 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> LCO for both SBGTS trains inoperab e and the 7 day LCO for B SBGTS train incoerable were terminated.

3408H

1 r LICENSEE EVENT REPOR7 (LER) TEXV CONTINUATION Form Rev 2.0 FAc1LITY NAME (1) DOCKE7 NUMBER (2) LER NUMBER g) Pace f3) j Year /// sequential // Revision p/jj/ / Wumber

/p/p/,

/ humber--

l Ouad Cities Unit One 01510 1 0 1 0 1 21 51_ L9 1 i I - 010 15 - 0 l 1 01 4 0F 01 5 TEXT Energy Industry Identification system (Ells) codes are identified in the text as (XX]

C. APPARENT CAUSE OF EVENT:

751s report is being submitted to comply with 10CFR50.73(a)(2)(iv). It requires the licensee report any event or condition that resulted in manual or automatic actuation of an) Engineered Safety Feature [JE] (ESF), including the RPS, except an actuation which is part of a preplanned sequence during testing or reactor operation. SBGTS is an ESF and the autostart was not preplanned.

The apparent cause of the event is an inadequate procedure. QOP 7000-1 does not adequately caution the NSO concerning the SBGTS autostart timer. QOP 7000-1 provided no information concerning SBGTS and referred the NSO to Q0A 7000-1, 120 Volts Alternating Current (TAC) Reactor Protection Bus [BU) Failure (One or Both Buses), for additional a;iomatic actuations associated with RPS bus transfers.

00A '000-1 step B.3.1. stated, "B SBGTS will start after 25 seconds if in STANDBY and power is not restored to B RPS within 25 seconds " The procedure did not stipulate that the 1/2 Group II isolation must be reset within 25 seconds to prevent 1/2 B SBG15 from autostarting.

D. SAFETY ANALYSIS OF EVENT:

The safety of the public and plant personnel were not affected by this event. RPS and SBGTS functionid as designed throughout the event.

OP personnel placed both units in a 7 day LC0 to be conservative to Tech Specs section 3.7.B.I.a. because they were un'ertain about the 1/2 B SBGTS autostart timer. Tech Specs section 3.7 B.I.a. also required a 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> LCO if both SBGTS chanra.s are inoperable. OP personnel placed both units in a 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> LCO to test the 1/2 B SBGTS autostart timer and terminated both LCO's immediately after the timer test, which took about two minutes.

E. CORRECTIVE ACTIONS:

The immediate corrective actions taken by the NSO were to reset the 1/2 scram and 1/2 ,roup II and III isolations, and to return 1/2 B SBGTS to STAN0BY mode.

The NSO verified tne operability of 1/2 SBGTS A in compliance with Tech Specs. The accuracy of the 1/2 B SBGTS autostart timer was also verifled.

OP personnel implemented a procedure change to 00A 7000-1 which corrected step B.3.1 to say "B SBGTS will start after 25 seconds if in STANDBY and power is not restored to B RPS and Group II is not reset within 25 seconds." 1/2 Group II and III isolations are retet using the ISOL RESET switch on 901-5 panel. Using this switch will also reset the 1/2 B SBGTS autostart timer.

{

340eM

4 LICENSEE EVENT REPORT (LER) TEX M 71NUAT10N Form;P'Ay 2.0

' LER NUMBER (6) Pard 3 )

., . FACILITY CAME (1)' DOCKE7 NUMBER (2)

Year sequer.t tal /// Revision 8

- )f

///) Number / Number __

Ouad citie? Unit one 0 l E I o 1 0 1 0 1 21 51 4 911 - 01015 - 01 1 .01 Sl 0F !01s TEXT Energy Industry identification system (Ells) codes are identified in the text as [XX)

F. PREVIOUS EVENTS:

There have been no similar previous events reported. As this event did not involve a component failure, a Nuclear Plant Reliability Data System (NPRDS) search was not conducted.

Y G. COMPONENT FAILURE DATA:

There is no component failure associated with this event.

a 6

3408H {

___ _ _______ _ _ _ _ _ - _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ - _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ - _ - - _ _ - _ _ _ _ - _ _ _

Retrieved from "https://kanterella.com/w/index.php?title=ML20029C124&oldid=2491749"