ML19343D548

Primary Coolant Sys Pressure Isolation Valves,Farley Unit 1, Technical Evaluation Rept

ML19343D548
Person / Time
Site:	Farley
Issue date:	10/24/1980
From:	Noell P, Stilwell T FRANKLIN INSTITUTE
To:	Polk P Office of Nuclear Reactor Regulation
Shared Package
ML19343D537	List: ML19343D536 ML19343D541 ML19343D548
References
CON-NRC-03-79-118, CON-NRC-3-79-118 TER-C5257-258, NUDOCS 8105050201
Download: ML19343D548 (7)

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s ATTACHMENT 2 9

TECHNICAL EVALUATION REPORT PR! MARY COOLANT SYSTEM PRESSURE ISOLATION VALVES ALABAMA POWER COMPANY FARLEY llNIT 1 NRC CCCKET NO. 50-348 N RC TAC NO.

12925 FRC PROJECT C3257

, NRC CONTRACT NO. NRC-C3-79-118 FACTASK 258 Prepared by Frank!!n Research Center Author: P. N. Noe11 The Parkway at Twentieth Street T. C. St:ilwell Philadelphia, PA 19103 FRC Group Leader:

P. N. Noell Prepared for Nuclear Regulatory Commission Washington, D.C. 20555 Lead NRC Engineer: P. J. Polk October 24, 1980 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or impilec, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosec in this report, or represents that its use by such third party would not infringe privately owned rights.

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1.0 INTRODUCTION

r De NRC has determined that certain isolation velve configurations in sys: ems connecting the high-pressure Primary Coolant System (PCS) to lower-pressure systems extending outside containment are potentially significant con:ributors to an intersystem loss-of-coolant accident (LOCA). Such configu-rations have been fund to represent a significant factor in the risk computed for core melt accidents.

De ssquence of events leading to the core melt is initiated by tho' con-l current failure of Iwo in-series check valves to function as a pressure isola-tion barrier between the blJ-pressure PCS and's lower-pressure system extend-ing beyond containment. Bis failure can cause an overpressuri:ation and rup-ture of the low-pressure system, resulting in a LOCA : hat bypasses containment.

• he NRC has determinad that the probability of failure of these check valves as a pressure isolation berrier can be significan:1y reduced if the pressure at each valve is continuously monitored, or if each valve is periodi-cally inspected by leakage testing, ul::asonic examination, or radiographic inspec: ion. De NRC has established a program to provide increased assurance

ha:.such multiple isolation barriers are in place in all operating Light Wa:e Reactor plants designa:ed by DOR Generic Implemen:ation Activity 3-45.

In a generic letter of February 23, 1980, the NRC requested all licensees

s iden:ify the following valve configurations which may exist in any of their plan: systems communicating with the PCS: 1) :wo check valves in series or 2) two check valves in series with a =otor-epera:ed valve (MOV).

Ic; plan:s in which valve configura: ions of concern are found to exist, licensees were further sequested :o indicate: 1) whether, to ensure integrity of :he various pressure isolation check valves, continuous surveillance or

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periodic :esting was currently being conducted, 2) whether any. check valves of ecucern were known :o lack in:egri:y, and 3) whether plant procedures should be revised or plant modifica: ions be made :o increase reliabili:y.

7:anklin Research Cancer (TRO) was requested by the NRC to provide tech-nical assistance to NRC's 3-45 activity by reviewing each licensee's submi::a1 6

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against criteria provided by the NRC and by verifying the licensee's reported findings from plant system ctawings. This report documents FRC's technical review.

2.0 CRITERIA 2.1 Identification Criteria for a piping system to have a valve con' figuration of concern, the follow-ing five items must be fulfilled:

1) The high-pressure system must be connected to the Primary Conlant System;

2) there must be a high pressure / low pressure interface present in the line; i

3) this same piping must eventually lead outside containment;

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4) the line must have one of the valve configurations shown in Figure l

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5) the pipe line must have a diameter greater than 1 ' inch.

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Valve Configuratiens Designated by the NRC To 3e Included in This Technical Evaluatica l

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2.2 Periodic Testing Criteria For -licensees whose plants have valve configura: ions of concern and choose-to institute periodic valve leakage :sseing, the NRC has established cri:eria for f tquency of testing, test condi: ions, and accep:able leakage rates.

These cri:eria may be su=marized as follows:

2.2.1 Frequency of Testing Periodic hydros tatic leakage testing *. on each check valve shall be accom-plished every time the plant is placed in the cold shutdown condition for refueling, each :ime the plan: is placed in a cold shutdown condi: ion for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if testing has no: been accomplished in :he preceding 9 months,

each ti=e any check valve may have =oved fro = the fully closed posi:icn (i.e., any time the differen- :ial pressure ac: css the valve is less :han 100 psig), and prio :o returning the valve :o service af:e: maintenance, repair, c: replacemen: verk is perfor=ed.

2.2.2 Hydrostatic Pressure Cri:eria Leakage :es:s involving pressure differentials icver than fune:ica pres-sure dif ferentials are per=i::ed in those types of valves in which service

essure vill

end to di=inish

he overall leakage channel opening, as by pressing the disk in:o or en:o the seat vi:h grea:e fe ce.

Ca:e valves,

check valves, and globe-:ype valves, having func: ion pressure differen:ial applied over the seat, are exa=ples of valve applications satisfying :hir requirement. When leakage :es:s are made in such cases using pressures lever than fune: ion maxi =u= pressure differencial, :he observed leakage shall be adjusted to fune:ica =axi=u= pressure differen:ial value.

Thit adjus:=ent shall be made by calcula:icn appropriate :o the tes: media and the ra:io Se:veen :es: and fune:isn pressure dif feren:ial, assuming leak -

age :o be direc:1y preportional :o the ;; essure differen:ial to :he one-half power.

2.2.3 Accep able Leakage Ra:es:

Leakage rates less than or equal to 1.0 gpm are censidered accep:-

e able.

e Leakage ra:es grea:e :han 1.0 gp= bu: less :han er ecual := 3.0 gp= are censidered accep able if :he la:e. =easured ra:e has no:

exceeded :he race de:er=ined by :he previous :es: by an amoun:

• o satis fy ALARA recuiremen:s, leakage may be measured indirec:1y (as from

he perfor=ance of pressure indica: cts) if acce=plished in accordance vi:h I

app :ved ;;ocedures and supper:ed by ::=pu:acions showing :ha: the =e: hod is :apable of demens::a:ing valve ::=pliance vi:h :he leakage cri:eria.

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that reduces the margin between the measured leakage rate and the maximum permissible race of 5.0 spm by 50% or greater.

Leakage races greater than 1.0 gpm but less than or equal to 5.0 s

e spa are considered unacceptable if the la:es: measured rate ex-caeded the rate determined by the previous test by an amount that reduces the margin between measured leakage rate and the maximum permissible rate of 5.0 gym by 50% or grea:er.

Leakage rates greater than 5.0 gym are considered unacceptable.

e 3.0 TECHNICAL ! VALUATION 3.1 Licensee's Response to the Generic Letter In response to the NRC's generic letter {Ref.1], the Alaba=a Power Company (A?C) stated (Ref. 2] that, having reviewed the High and Low-Head Injection, Nor=al charging and Letdown Systems, none of the valve configurations conform,

to Event V.

The licensee further s:ated, "'ihe present plant design and inspection cc==i:ments ar,s more than sufficient to ensure that the hypothetical Event V a:ciden: could not be a problem at our f acility."

Nevertheless, the Low-Head Injection System bo -leg was discovered by ?RC

o contain a valve con figuration.of concern.

I: is FRC's understanding that, wi:h APC's concurrence, the NRC will direc: APC te change its Plan: Technical Specifications as necessary :o ensure that periodic leakage testing (or equivalent testing) is conducted in accor-dance vi:h the. criteria of Section 2.2.

3.2 FRC Review of Licensee's Response

?RC has reviewed the licensee's response agains: the plant-specific ?iping and I,cs:ru=entation Diagra=s (P& ids) [Ref. 3] that might have the valve con-i figuraticus of concern.

FRC has also reviewed the efficacy of ins:ituting periodic :es:ing for the check valves involved in this particular application with respect to :he re-due:ica of :he probability of an intersyste= LOCA in :he Low-Head Injectioc Syste=, hot-leg piping lines.

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In its review of the P& ids IRef. 3} for Farley Uni: 1, FRC found the following piping system to be of concern:

The piping system of concern in the Low-Mead Injection System lead-ing to the hot-leg side of the Primary Coolan: System Loops 1 and consists of :wo piping branches each having a two check valve in-series configuration vi:5 both branches joining at a single motor-operated valve (MOV) outside containment. The high-pressure / low-pressure interface is on the upstremn side of the single MOV.

The

-valves of concern in :his system are listed below:

Low-Head Injection System Looe 1, hot leg high-pressure check valve, QlI21V0 7A high-pressure check valve, QlI21V076A high-pressure common Mot', Q1E11VO 4, normally closed (n.c.)

Looo 2, hot leg high-pressure check valve, Q1521V0773 high-pressure check valve, QlE21V0763 high pressure ec= mon MOV, QlEllV044, n.c.

• n accordance with the criteria of Section 2.0, FRC found no other valve ccnfigura:icns of concern exis:ing in :his plan:.

FRC reviewed the effectiveness of instituting periodic leakage testing of the check valves in these lines as a neans of reducing :he probability of an in:ersystem LOCA occurring. FRC found :ha: in:roducing a program of check valve leakage :esting in accordance wi:h :he criteria summarized in Section 2.0 will be an effective measure in substantially reducing the probability of an intersystem LOCA occurring in these lines, and a means of increasing the prebdaili:y tha: these lines vill be able to perform their safe:y-related functiena.

It is also a step :ouard achieving a ccrresponding reduction in

he plant probability of an intersys:em LOCA in Farley Unit 1.

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4.0 CONCLUSION

Eased on the previously docketed information and drawings made available for FRC review, FRC found that the hot-leg branches of the Low-Head Injection System in Farley Unit I contain a valve configuration of concern (identified in Figure 1). Thus, if the licensee's review of the valving configurations in the hot-leg branches of the Low-Head Injection System confirms FRC's finding, then the valve configurations of concern existing in Farley Unit 1 incorporate the valves listed in Table 1.0.

If APC modifies the Plant Technical Specifications for Farley Unit 1 to incorporate periodic testing (as delineated in Section 2.2) for the check valves itemized in Table 1.0, then FRC considers this an acceptable means of achieving plant compliance with the NRC staf f objective: of Reference 1.

Table 1.0 Primary Coolant System Pressure Isolation Valves System Check Valve No.

Allowable Leakare*

Low-Head Injection Loop 1, hot-leg Q1E21V077A Q1E21V076A 1

Loop 2, hot-leg Q1E21V0773 Q1E21V0763 S.0 REFERENCES 1.

Generic NRC letter, dated 2/23/80, from Mr. D. G. Eisenhut, Department of Operating Reactors (DOR), to Mr. F. L. Clayton, Jr., Alabama Power Ccepany (APC).

e 2.

Alabama Power Company's respense to NRC's letter, dated 3/24/80, from Mr.

F. L. Clayton, Jr., ( APC) to Mr. D. G. Eisenhut (DOR).

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• To be provided by licensee at a future date in accordance with Section 2.2.3.

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'.is : of examined P& ids:

Bechtel Corporation Drawings of Farley Unit 1:

D-175037 (Rev. 7) Sh. 1 of 3 D-175037 (Rev. 9) Sh. 2 of 3 D-175037 (Rev. 7) Sh. 3 of 3 D-175038 (Rev.12) Sh.1 of 3 D-175038 (Rev. 10) Sh. 2 o f 3 D-175038 (Rev. 6) Sh. 3 of 3 D-175030 (Rev. 3) Sh.1 of 4 D-175039 (Rev. 11) Sh. 2 of 4 D-175041 (Rev. 0)

D-175047 (Rev. 12)

FSAR Drawings of Farley Unit 1:

Fig. 9.2-1 Sh. 1 of 4 Fig. 9.2-2 Sh. 2 o f 4 Fig. 9.2-3 Sh. 3 of a Fig. 9.2-4 Sh. 4 o f 4 Fig. 9.2-5 8

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