ML20046B412

LER 93-007-00:on 930628,noticed That Hydrogen Pressure Setpoint Found to Be Set Above 10 Psig.Caused by Personnel Error.Mod Design Package Developed to Raise Pressure Regulator setpoint.W/930728 Ltr

ML20046B412
Person / Time
Site:	Crystal River
Issue date:	07/28/1993
From:	Boldt G, Froats E FLORIDA POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
3F0793-14, 3F793-14, LER-93-007, LER-93-7, NUDOCS 9308040176
Download: ML20046B412 (4)

Text

. - __

. e

(, 'q_

, r, G. ;e5

. g .o 3 : -

1 Florida Power conPosai4 os Crystal River Unit 3 Docket No. 50-302 July 28, 1993 3F0793-14 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555

Subject:

Licensee Event Report (LER)93-007

Dear Sir:

Enclosed is Licensee Event Report (LER)93-007 wt icn is submitted in accordance with 10 CFR 50.73.

Sincerely,

/

G. L. oldt Vice President Nuclear Production EEF: mag Enclosure xc: Regional Administrator, Region II Project Manager, NRR Senior Resident Inspector 030058 y l

.\

9309040176 930728 (

PDR ADDCK 05000302 y A Florida Progress Company s PDR c(>:J

AePFmED OMS O. 1 0410.

i pgO M. u n ,etEAR moumrORv COMMISSION EXPIES 6/31/96 INF ATION L CT M T .

, LICENSEE EVENT REPORT (LER) ggggggugEgTyp MMILEA*?!"a'i'aFPja! , ' "th OFFICE OF MANAGEMENT AND DVDGET.W TON DC 20603.

FACILJfY PMME (1) DOCKET NUMEIER (2) PAGE (3)

CRYSTAL RIVER UNIT 3 (CR-3) 0lsl0l0l0l3l0l2 1 lOFl 0 l3 10 LE (4)

Raised Satpoint on Pressure Regulator Leads to Operation Outside Design Basis.

EVENI aJTE (b) LER NUMHl.R(6) KPORY DATE p) OTHER FACRJTIES WVOLVED (8)

SEQUENTIAL REVIS80N FActLITY NAMES DOOCET NUMBEFXS)

MONT H DAY YEAR YEAR NUMBER -

NUMBER MONTH DAY YEAR fe;A 0l 5l 0l0l0l l l 0lG 2 l8 9 3 9l3 -

0l0l7 -

Of0 0l7 2l8 9l3 N/A 0l6l0l0l0l l l C[PL T THIS HEPORT IS SUBurrTI D PUR90 ANT TO THE NQUtHEMENTS OF 10 CFM $: scNECK ONE pa song or THE FOL10wNss) (11) 20.402(b) 20.405(c) 50.73(aK2)(iv) 73.71(b)

R 20.405(aX1X1) 60.3ft(cX1) 60.73(aXPXv) 73.71(c)

(10) l1 j 0l 0 20.406(aX1Xil) _

60.3e(cX2) so.73(eX2Xvir)

OTMR( m '

20.406(aX1Xin) 60 73(aX2XI) 60.73(aK2Xv6iiMA) M64r 20.405(aX1Xiv) X 60.73(aXPXW) 60.73(aKPXviir)(s) 20 405(aXIXv) 50 73(aX2Xill) 5033(aX;Xx)

LICENSEI CONTACT fCR THIS ER (12)

NcME TEA.EPHONE. NUMBER AREA CODE E. E. Froats, Manager, Nuclear Cornpliance 9}0l4 5l e l 3 l- l 4l 7 l 0 l s COMPLETE ONE L8ME FOR EACH COMPONENT F AILUE IN TPBS FEPORT (13)

CAUSE SYSTEM COMPONENT MANUFAC- KPORTABLE -

CAUSE SYSTEM COMPONENT MANUFAC- EPORTABLE  : , ,

TURER TO NPHDS TURER TO NPROS -

1 I I I I I 1 1 I I I i 1 1 I I I I I I I I I I I I I I SUPPLEMENT AL EPORT EXPECTED (14) EXPECTED MONTH DAY YEAR SUBMISSION

] ABS YES (W roe semp** EWCTED Auam459 DON Daft) 1 hACT (L ' A er f*M apeces. d e , apswsnewt htteen songe-espece enweveren awe (16)

NO DAT E (15) l l l On June 17, 1993, Crystal River Unit 3 (CR-3) was in Mode 1 (POWER OPERATION) at 100% Rated Thermal Power producing 865 Megawatts. The hydrogen pressure regulator valve MUV-491 for the Makeup Tank (MUT) was found to be set above 10 pounds per square inch (psig). MUV-491 was reset to control at 10 psig.

Engineering was notified that operating above the 10 psig setpoint was a suspected design basis issue. On June 28, 1993, the Nuclear Shift Supervisor was notified that the hydrogen pressure setpoint to the MUT had exceeded the Appendix R Design Basis. A 1985 Appendix R fire analysis postulated a spurious opening of the hydrogen addition solenoid operated control valve MVV-143 due to a fire induced short-circuit. This would place 50 psig overpressure on the MUT, possibly resulting in hydrogen entrainment in the Makeup Pumps (MVP) suction piping under certain drawdown conditions to compensate for system shrinkage during cooldown. MUV-491, a self-contained pressure regulating valve, was installed in the hydrogen addition line to maintain pressure at 10 psig to reduce this possibility without operator action. The setpoint for MUV-491 had been recently adjusted to increase the MUT pressure in order to improve chemistry parameters in the primary coolant. An Operations Study Book (OSB)

Entry was made cautioning operations personnel that such actions may create unauthorized plant modifications.

He rom, = (S-.o>

f NHC ONM 3enA LLE NUCLEAR KCULATC3Y COMadtBSION APPRCWED OMB NOL 316D-0104 ExmEs smn s LICENSEE EVENT REPORT (LER) ggTgaugrN g Re g g g w gTg

. TEXT CONTINUATION ggggmgn44;Eggy 5

AN O H APE DUCTION CT 0d).

OF HCE OF M ANAGEMLNT AND BUDGE 1, WASH TON OC 20603.

FACUTV NAME (1) DOOKET NUMBEH g) LER NUMBG (6) PAGE M YEAR e CRYSTAL RIVER UNIT 3 (CR-3) 0l5l0l0l0l3l0l2 9l3 -

0l0l7 -

0l0 0 l 2 lOFl 0 l 3 TEXT ta asow esce a wowed use emmnwunc rom sas.a e (17)

EVENT DESCRIPTION:

On June 17, 1993, Crystal River Unit 3 (CR-3) was in Mode 1 (POWER OPERATION) at 100% Rated Thermal Power producing 865 Megawatts. Operators noticed a reduction in the time required to add hydrogen to the Makeup Tank (MUT) [CB,TK]. The MUT has a pressure regulating valve MUV-491 [CB,PCV) with a design setpoint of 10 psig.

At approximately 18:15 on June 17, 1993, the setpoint was found to be greater than 30 psig. MUV-491 was reset to control at 10 psig. Engineering was notified to review this event as a suspected design basis issue.

On June 28, 1993, the Nuclear Shift Supervisor was notified that the hydrogen pressure setpoint had exceeded the Appendix R Design Basis. This condition is being reported in accordance with 10CFR50.73(a)(2)(ii)(B).

CAUSE:

This condition is considered to be the result of human error. An increase in the MUT hydrogen pressure has been considered desirable in order to improve oxygen removal in the Reactor Coolant System (RCS) [AB] and had been identified as an industry good practice. Several meetings and discussions had been conducted with Engineering, Operations, and Chemistry personnel in an attempt to achieve this goal. Engineering had reviewed and approved an increase in MUT overpressure but had not completed a review of the appropriate method to establish the increased pressure. Apparently an operator, regarding it as appropriate, raised the setpoint on MUV-491 before the necessary design change documents were completed.

EVENT EVALUATION:

A 1985 Appendix R fire analysis postulated a spurious opening of the hydrogen addition control valve MUV-143 [CB,FSV] due to a fire induced short-circuit. MUV-143 is a 3/4 inch solenoid control valve located in the hydrogen addition line.

The analysis concluded that a fire in certain areas of the plant could cause MUV-143 to spuriously open. This would place 50 psig overpressure on the MUT, possibly resulting in hydrogen entrainment in the Makeup Pumps (MUP) [CB,P] suction piping.

Spurious operations based on Appendix R concerns must be addressed by one of two ways. Actions to preclude the spurious operation must be taken, or compensatory actions must be available to mitigate the effects of the spurious operation within eight hours. MUV-491, a self-contained pressure regulating valve, was installed in the hydrogen addition line to maintain pressure at 10 psig as a way to preclude the possibility of hydrogen entrainment without the need for mitigating actions within eight hours.

t The setpoint was based on a calculation that had been developed to determine the time available before both the MUT and the Borated Water Storage Tank [BP,T) reached low-low levels at certain drawdown conditions. This calculation utilized a constant 10 psig overpressure and concluded this would allow an exceptionally N8C F orm 3SSA (6-89) g

MC ($ts anu U.S. NuaEAR MOULATORY COMMISSWON APPFCVED OMB NO,3160-4104 EAPIMS 6/31/96 LICENSEE EVENT REPORT (LER) g T3o grot g g sp goNTggmg TEXT CONTINUATION g g e g g U g Eg u g T g ,C g AN O H APE Fd~ DUCT CT 10'd),

OF FICE OF MANAGEMENT AND BUDGE'T, WASHI TON DC 20503, F ACRJTY NAME (1) DOCR.ET NUMDER(2) LER NUMBEJ4 (s) PAGE (3) sEQUEM M -

REVtmON Y'^" " " *'" ~

CRYSTAL RIVER UNIT 3 (CR-3) ol sl oj ol ol 3l ol 2 ol3 -

olol7 -

olo o l 3 lOFl 0 l 3 TEXT in - . , au ,w we r.,. m4. <t 7) long time from an Appendix R viewpoint for an operator to isolate the MUT from the MUPs. This calculation did not determine the highest allowable overpressure setpoint.

Based on the discovery of the change in setpoint, a new Appendix R Makeup Tank Overpressure Evaluation was performed. The evaluation determined that a setpoint of more than 20 psig exceeded the Appendix R Design Basis.

The postulated spurious opening of MUV-143 by an Appendix R fire is not considered a significant possibility. Although mitigating actions would have been required  ;

if MVV-143 were to spuriously open when MUV-491 was set higher than 20 psig, either i venting the hydrogen from the MUT or isolating the MUT from the MUPs would have prevented hydrogen entrainment in the MVP suction piping.

CORRECTIVE ACTIONS:

The setpoint for MUV-491 was reset. An Operations Study Book (0SB) Entry was made to increase the awareness of operations personnel for the requirements for proper documentation before making any plant modification. A modification design package has been developed to raise the pressure regulator setpoint to address the industry good practice concern.

PREVIOUS SIMILAR EVENTS:

There have been eight previous events concerning operation outside Appendix R Design requirements. This is the first such occurrence involving MUV-491.

i l

l l

1 l

l l

l WC Form 366A (6-89)  !