ML20029B590

LER 91-004-00:on 910211,standby Liquid Control Sys of Unit 1 & 2 Inoperable.Caused by Inadequate Mod Testing.Engineering Dept Evaluating Data & Temporary Procedure 6589 Generated. W/910308 Ltr

ML20029B590
Person / Time
Site:	Quad Cities
Issue date:	03/08/1991
From:	Bax R, Maclennan M COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-004, LER-91-4, RLB-91-076, RLB-91-76, NUDOCS 9103130068
Download: ML20029B590 (6)

Text

.. ,. -.. ._,-_.~_-_...__._..-___.__._m_

._.____._____._.-__.__._s j 7 ]O Commonwealth ECoon

'/ ound Cit:s Nucleat Power Staton i e'

' '[ g $ oordova,Ilknos 61242 9740

- 22710 206 Avenue North l Telephone 309/654 2241 RLB-91-076  ;

i e

March 8, 1991 U -S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 ,

Reference:

Quad Cities Nuclear Power Station Docket Number 50-265. DPR.30, Unit Two

. Enclosed is Licensee Event Report (LER)91-004, Revision 00, for Quad Cities ,

Nuclear Power Station. .

t This report is submitted in accordance with the requirements of the Code of ,

Federal Regulations, Title 10. Part 50.73(a)(2)(v). The licensee shal1~ report any event or condition that alone could have prevented the fulfillment of the ,

safety, function of structures or systems that are needed to shut down the reactor and maintain it-in a. safe shutdown condition. .

Respectfully, COMMONWEALTH EDISON COMPANY-QUA0 CITIES NUCLEAR POWER STATION

'O

[R.L.-Bax:

Station. Manager RLB/TB/dib .

Enclosure cc: R. Stols T.:Tay1_or INPO Records Center NRC Region-III i

sTHGR 57 9103130068 910308 i >

PDR S

ADOCK 05000265

• j l p

(

i PDR

_ . , _ _ . . _ . . _ . _ , . . . . _ . _ . , _ . . . . _ . _ . _ _ . _ . . __ . . _ _ . . . - ~ . . . . _ . ,-

i 4

j' i' LICth$ti (VENT RtPORT (LER) i Facility Name (1) Docket Numoer (3) . fAgg Q1 nnaa citin twt twa 01 11 of of 01 21 si s tlof!0l1 2

71tle (4)

! SaltL MD.111.$1LC Declared inan Due to InggrJ3yttg lguina and _talgg1311 ggt,gf Pumn NP1H Event _ggle f$1 Ltk Number f61 Rgggt1_QL(e (7) Othtr Facilitigt involvgL181 I

Month Day Year Year Sequential Revision Month Day Year Facility NamtWadtLNeet I i d

II-- -

g I[s

_01 FI OLQLQLtLi;.4 i

~~~ "'

• of 2 11 1 .91 1 91 1 0l014 010 0l3 of a 91 1 01 El 0l_Q.1 01 1 1

[ TH!s REPORT !s $uBMlfft0 PUR$uANT 10 THE Rtou!RtMENTS OF 10CFR

[ Chick one er more Of the followirial (111 4 20.402(b) 20.405(c) , 50.73(a)(2)(iv) _ 73.71(b)

POWER 20.405(4)(1)(i) , 50.36(cM1) L 50.73(a)(2)(v) __ 73.71(c)

LEVil 20.405(a)(1)(11) 50.36(c)(2) 50.73(a H 2)(v ti) ._ Other (Specify

_ 101

( 0 a 6 . 20.405(a)(1)(iii) 50.73(a)(2)(1) 50.73(a)(2)(vi11)(A) in Abstract

/jjj/jj/jjjjjjjjjj///jj/jjffjj/

// / ////////// ///// _ 50.73(a)(2)(11) 50.73(a)(2)(vitiHB) below and in

/

'thhIhhhhhhhhhll$hh/hhhhIhhh t l

'20.405(

0**0II*O aH1 ~ )(iv )

00I*' ~ $0I*" '** I Litigitt..CONTAff FOR TH11_LER (121 ,

hame ffLEPHQhi.EUMBLP AREA C001 Michael F. Mag,lannan Ext. 2110 1l0l9 61 El 41 -l 21 21 41 COMPLETE ONE LINE FOR EACH COM N F All.yRLQil(glgt0 IN TH11 REPORT (131 CAu5t OYsitM COMPONENT MANuFAC. REPORTABLE CAu$t I sV5ftM COMPONENT MANuFAC- REPORTABLE TURER TO NPRD1 TUgtR 10 NPRDS

,.,,,,,, I i 1 I i 1 1 i i i l 1 i I

_ l l 1 1 I i 1 1 I I i l I l .

$UFFLtMENTAL. REPORT EXP[tft0 (141 . Expected battlLLO&y_LItar.

Submission

lYet fif_ves. enmolete EXPtetto SU1811110N Daft) X l ko 1 l l1 AB$fRACT (Limit to 1400 spaces, i.e. approximately fif teen single-space typewritten lines) (16)

ABSTRACT:

On February ll, 1991, at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />, Unit One was in the SHUTDOWN mode, and Unit Two was in the RUN mode at 86 percent of rated _cor6 thermal power. During the performance of a 9ecial test on Unit on to determine the available Net Positive Suction Head (NPSH) of the Standby Liquid Control (SBLC) pumps, the pumps began to cavitate unexpectedly, The SBLC systems of both' units were declared inoperable and a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Limiting Condition of Operation (LCO) was entered for Unit Two, untti the l ability of the pumps to fulfill their design function was proven.

On February 12, 1991, at 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />, upon approval of an evaluation of the system, L

administrative controls were placed on the tank level and temperature to ensure adequate NPSH was available, and one pump on each unit was declared operable. This put Unit _Two in a seven-day LCO, On February 14. 1991, a second evaluation, which verified the ability of SBLC to perform properly during two pump operation, was approved. The SBLC systems for both units were subsequently declared fully c'perable, and the LC0 terminated.

The causes of this event are inadequate modification testing and an error in the original design calculations. Corrective actions included analysis of test data and administrative controls to assure adequate NPSH was available to the pumps.

Additional testing will be performed to further demonstrate the adequacy of the pumps, 33f4H

,m- '.rw m e-a-w -- t- e -a --y  ?'y-

'v= ----nn -

-*we

- . - . - ._ ~ ~-- .- -. _ _ . . ~ _ . _ . ~ . _ - ~ - - . . - - - . - _ . .

LI([ ggt tyLNT REPORT (Ltti f t%7JNf1 EAT 10N Form Rev 2 A FACILITY NAH( (1) DOCKET COMetR (2) Lta tusett (6) Pane til

, Year // sequential /j//p Revision p/p//p

/ Nunear p//

/ Ni ggtgg_

ouad Citiet unit.Two 0 l E l o i 0 l 0 l 21 61 1 911 - 01014 - O l 0 01 2 0F ol i TEXT Energy Industry Identification system (!!!s) codel are identified in the text as (XXI t PLANT AND SYSTEM IDENTIFICATIO_N:

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

EVENT IDENTIFICATION: Both Units SBLC Declared Inop Due to Inadequate Testing and -

Calculation of Pump NPSH.

A. C_ONDITIONS PRIOR TO EVENT:

Unit: Two Event Date: February 11, 1991 Event Time: 1320 Reactor Mode: 4 Mode Name: RUN Power Level: 86%

This report was initiated by Deviation Report 0-4-02-91-020 RUN Mode (4) - Run - In this position the reactor system pressure is at or above -

825 psig, and the reactor protection system is energized, with APRM protection and RBM interlocks in service (excluding the 15% high flux scram). i B. DESCRIPTION OF EVENT:

On February 11, 1991, at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />, Unit One was in the SHUT 00HN mode for scheduled refueling outage Q1R11, and Unit Two was in the RUN mode at 86 percent of '

rated core thermal power. Technical Staff personnel were performing Special Test number 1-158, Standby Liquid Control (SBLC) (BR] Pump [P) Net Positive Suction Head

-(NPSH) Test, on Unit One. The purpose of this test was to colect data to determine the available NPSH of the SBLC pumps. The lA SBLC pump was running for the test, heating and recirculating water to the SBLC test tank (TK) in order to simulate worst case pumping conditions. At 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />, the pump began to cavitate before expected. Operations personnel stopped the pump and terminated the test per the test instructions. Engineering was notified and given the test results for ,

further. analysis.

~

At 1717 hours0.0199 days <br />0.477 hours <br />0.00284 weeks <br />6.533185e-4 months <br />, the Shift Engineer (SE) declared the SBLC systems for both units inoperable retroactive to 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />, and an Emergency Notification system (ENS) phone call was made to satisfy the requirements of 10CFR$0.72(b)(2)(111)(A). This placed Unit Two in a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> LCO per Technical Specification 3.4.0. -

At approximately 2230 hours0.0258 days <br />0.619 hours <br />0.00369 weeks <br />8.48515e-4 months <br />, the Engineering Department completed an evaluation on I

the operability of the SBLC system. This evaluation stated that single pump s operation of SBLC could be assured if a minimum storage ta v level of 3819 gallons.

at a minimum Boron concentration of fourteen percent and a maximum temperature of ,

100 degrees Fahrenheit, was maintained. The abi'ity of the SBLC system to function

l. during two pump operation was still in question at this time, due to the possibility of a resonance condition between the pumps which could affect the NPSH, 4

3364H

-.e~ , + - , . .

',,,--,-....,,,-._,-~y,

- - - ,r, _ . _ _ ,-m, . , . . . . . , m.-----,, . , , , . , - - . . . + , , . , . . . , - - s -,,.

1 Littkitt (VENT REPORT _fLER1 ftXT CONTINuAff0N Form Rev 2.0 FACIL!fY NAME (1) DOCKET NUMBER (2) J R MLeetR fEl Page (3)

, Year ///

jjp sequential //p/j Revision

/// Number j//

/ _Nght Quad citiet Unit two o1110l010i fl 6l 1 911 - 01,,,g14 - 0l 0 01 .1 0F DL,,$

TixT. Energy Industry Identification system (E!!s) codes are identified in the test at [xx)

At approximately 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br /> on February 12, 1991, the evaluation was reviewed and approved by the station Onsite Review (OSR) committee. At 0920 hours0.0106 days <br />0.256 hours <br />0.00152 weeks <br />3.5006e-4 months <br />, the Shift Engineer received the approval. Administrative controls were established at that >

time to verify the tank level and temperature twice per shift, and the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> LCO was terminated. Because only single pump operation was justified, the station remained in a seven day LCO as of February 11, 1991, at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />. 005 1100-01, j Standby Liquid Control System Component Outage Report, was initiated for each unit retroactive to that time. Further, Temporary Proc'edure 6589 was generated, which ,

, revised 00P 1100-2, Injection of Standby Lig'Jid Control, to allow only single pump

, operation of the SBLC s~ystem.

At 1130 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.29965e-4 months <br /> on= February 12, 1991, a second ENS phone call was made to update the status of the SBLC system. ,

On February. 14, 1991, the station received a second evaluation from the Engineering Department on the operability of the SBLC system. This evaluation stated that there would be no pump interaction that would significantly reduce the flow rate of  ;

the pumps. The lengths of pipe which would have resonance frequencies similar to ,

those generated by the pressure pulses of the SBLC pumps were much greater than any  !

of the existing sections of SBLC piping. ,

The Onsite Review committee reviewed the second evaluation, and recommended that l the SBLC systems for both units be declared fully operable, provided the-level in '

the main SBLC tank was maintained above 8.04 feet (3819 gallons) and the tank temperature was maintained below 100 degrees Fahrenheit. At 2115 hours0.0245 days <br />0.588 hours <br />0.0035 weeks <br />8.047575e-4 months <br />, the Shift Engineer received the recommendation, declared the SBLC systems for both units j operable, and terminated the outage report and the temporary procedure.

C. APPARENT CAUSE OF EVENT:

This report 1s being submitted to satisfy the requirements of. '

10CFR50.73(a)(2)(v)(A): The licensee shall report any event or conditions that alone could have prevented the fulfillment of the safety function of structures or <

systems that are needed to shut down the reactor (RCT) and maintain =lt in a safe '

shutdown condit1ons.

The apparent cause of this event is inadequate modification testing of the SBLC system, and an error in the original design calculations for the system. Special test 1-158 was run as a result of questions raised during a review of Modification M4-1(2)-85-42 SBLC System Two Pump Operation. -This modification added a second pump $Uction line to the SBLC system and provided circuitry to allow for two pump operation. It was installed in order to comply with 10CFh50.63 Requirements for Reduction of Risk from Anticioated Transient Without Scram (ATHS) Events to Light-Water-Cooled Nuclear Plants. The testing for this modification verified that two pump operation was possible, and that greater than 80 gallons per minute could be maintained per the design requirements. However, the flow rate was verified over a short duration and at a high tank level. This did not allow time for the possibility of the development of a resonance condition, nor did it verify that adtquate NPSH was available at low tank levels.

3364H

~ .~. _ .n _ - - . - .

o ,

d Lffthtfi IVtkt kiPok7 fliel YtXT (DNTiku4710k Ferrr Rav f.0, Pana fM

[{ FAc!LITY NAME (1)' _

00CKl? CUMHR (2) Lit,,, DUMBER M1 Year sequential Revision W

ffj/

// ///

,//p f

j //f, kunhar / humhgt

'nuad fitiat Unit Two 011 i 01010121fil1 911 - DIoi4 - 01 0 -01 4 0F Sl K TEXT (nergy Industry Identification system (t!!s) C00es are identified in the test as (XX)

'Further review of design documentation revealed that when the original NPSH calculations were performed on the system, the effect of acceleration head was not considered. Acceleration head is & pressure fluctuation caused by inertial forces in low speed reciprocal pumps.

D. SAFETY ANALYSIS OF EVENT:

The safety significance of this event is minimal. Technical Specifications require +

each of the SBLC pumps to provide 40 gallons per minute (GPM) of at least 14 weight

, percent Boron solution for a total injection of 3321 gallons to assure safe j shutdown of the reactor. Due to the extremely conservative nature of the ,

calculations used to reach these criteria, the SBLC_ system has adequate capability

~to perform its intended function. If an accident which required initiation of the SBLC system had occurred, the required amount of Boron could have been pumped into-

! the~ reactor.

h The normal Boron concentration at the minimum tank level is 15.4 weight percent.

This increases the NPSH available to the pump, and reduces the amount of solution required'to be pumped in order-to achieve the proper concentration in the reactor.

The normal tank temperature is 95 degrees Fahrenheit, not 120 degrees as assumed in LNPSH calculations.- This-too increases the NPSH available.

Design calculations require'the'SBLC system to bring the reactor suberitical by 3 percent delta-k or greater-at cold shutdown conditions. ' General Electric (GE) '

Nuclear Services Information letter (SIL)'325 s'ates that a calculated SBLC shut 6own margin of 2.67, delta-k at a reactor coolant temperature of 20 dearees Celsius is adequate to assure that SBLC will raaintain the plant in a suberitical -

state.

Taking the above'conservatisms into consideration, it'has been determined that the

-SBLC system is capable of performing its_ intended function. In order to add  ;

additional' safety margin _and to confirm satisfactory operation of the pumps at low i NPSH conditions, the tank' low = level limit has been raised and the maximum operating temperature lowered until further testing can be completed and evaluated.

, E. ' CORRECTIVE ACTIONS; The.immediate corrective action after the test data was collected was to request the Engineering Department to evaluate the data and determine.whether or not a problem existed. The station declared both Unit's SBLC systems inoperable and -

subsequently entered a 24_ hour LCO on Unit Two.

.Upon receipt and.Onsite. Review of an analysis by the Engineering Department, Operating personnel-established administrative controls on the system per the ,

evaluation and generated Temporary Procedure 6589 to allow only single pump operation.1 Operating then declared one pump on each unit operable. This placed Unit Two inte a seven day LCO, l

L 3364H-L ..

~,.~ - -r.-.- v,-.----n,--,.--,n-+.-.--_--,-~+,,--.-w.n,.-c.,+,.--,n,,_n-en.-~~ ,n,w.-- ,--n-w,--, ,,-w.,-n,n., --+w

._a . . - ~ ~ _ --- .~.- - - - - - -- - ~~~ ~ -~ -- - - - - - - - - - - " ~ - - - -

1 LlftNitt IVEN7 REPok? (Ltt) T[KT CONTINUATION Form Ray 2.L ,

FACIL!?Y NAME (1) DOCKET NUMBER (3) LER NUMBER (6) Paaa f31

/jj/,/ sequential

Year 1

// Revision l

/// NMar' /j/j/

f

/ I Numb *L J

ound fitiet Unit Tao 0111010 1 0 l 21 61 5 9l 1 . 01 0 l 4 - 01 0 01 5 0F of E VtXT Energy Industry Identification system (t!!S) codes are identified in the text as (XX)

! Upon receipt and review of further analysis by Engineering, the SBLC systems for i bMh units were declared fully operable, and the temporary procedure and seven day LCO were terminated.

! In order to further demonstrate the adequacy of the SBLC system pumps, a second special test will be conducted. This test will use both SBLC pumps on Unit One to pump down the SBLC tank to temporary tanks. Pressure equal to the required SBLC system injection pressure will be maintained, and ficw will be monitored to assure an adequate flow rate is maintained. The SBLC main tank temperature will also be-adjusted as necessary to verify proper operation at high tank temperatures-(NTS 2652009102001).

F. PREVIOUS EVENTS:

There have been no previou, events in which_the available NPSH of the SBLC pumps was questioned, nor have there been any previous events in which the SBLC pumps had insufficient flow rates due to unknown causes.

As this event did not involve a component failure, a Nuclear Plant Reliability Data System (NPRDS) search was not conducted.

G. COMPONENT FAILURE DATA:

This event does not involve a component failure.

l 3364H

-w--.-,r, - . - __wm-_w-=,,e,-m.-.,...,--w,,w ,,,v .-,y,,,,,,, ,,,,,-4. , , , . - - , --w.+-,.-,-w,--w-,,, -ww,-,-y,-y --urg.,-. ...o- , - . ,- ...-,--.*-..%i, m. ,=e-s~