ML19220B696

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Summary of 750417 Meeting W/Utility in Bethesda,Md Re Containment Isolation Features
ML19220B696
Person / Time
Site: Crane Constellation icon.png
Issue date: 04/22/1975
From: Washburn B
Office of Nuclear Reactor Regulation
To:
Office of Nuclear Reactor Regulation
References
NUDOCS 7904270230
Download: ML19220B696 (12)
v • d • e


Text

{{#Wiki_filter:. 9 UNITEO STATES NUC LE A R REGULATCRY COMMISSION W ASHIN GTON. O. C. 20555 April 22, 1973 O a.. -- vO m 0- 3.,0 w r-i u .a n n. C A T.'. S. .M e *.. 0 y c '.'

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aw. -ersey Central Pcwer & Light Company Pennsylvania Electric Ccapany FACILITY 2 Three Mile Island Nuclear Station, Unit 2 er, -.. c.., g v. o.r.v.er. Is.;u, n, q. r - 1,, 1 4 7 5, ",.v "...'3.Mr. R. ^a P O 7 - -- ". r D I O 'i .~ a..r. c n.,0 s.,y.n D A _c -..S o-C O... A.- s..y.,,,, I o.., -,, r 0 u.. e Ea,.,s. eS O R..a.Rr., w m.. s. w wv .u . -~ u ws1. MILZ ISLAND NUCLEAR STATION UNIT 2 (TMI-2) Members of the Nuclear Reacter Reculation staff met in Bethesda, Maryland, on April 17, 1975, with ree.resentatives of Metroc.oli-r., ~ -- ,.. --. s v.. C...,ea..", -- u.' s m "- c o =. --... a ~ 4 'ie s '.c

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.b.' ^s v.k.'.., .# c. a lines penetrating the containment in TMI-2. n,- > ~- *- -,,.a saw.w vm.. The TMI-2 Preliminary Safety Analysis Report (PSAR) and the ccnstruction permit (CP) hearin"v record included a ccanitment bv the ac.clicants to incer crate a fluid blockinc. cr isolation valve seal water feature in the final desien of the clant. The ~ purpose c. tnis teature was to := prove tne e:f ectiveness c:. the containment isolation valves by providing a fltid seal in lines '.e."..; c.". c ^ u ' d -...."-...i-=.a w.i.."...". e w~ ^...= 1'.... a.. t.a * ~..c e y.. a.- a_ a.d "c v um - b ensure icw leakage rates frer the centainment under accident .-...4. 4 4,,s. ..u..: s

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.i . Discussion The ac.c.licants reviewed the PSAR concent of the fluid block feature and its disadvantages. The PSAR conceptual design and typical valve arrangements are given in Figure 5 - 10 ( Attachme nt 2). The applicants stated that a lack of redundancy in the original flaid block header concept made it susceptible to single break failure, valve failure could fleed the contain-ment during normal operation and the carbon steel system is unsuited for use with berated water as the blocking fluid. The applicants stated that the intention of the PSAR fluid block feature was to eliminate only valve stem leakage (see ) in the event that valve packing leaks were present and that stem leakage was more important than seat leakage since seat leakage wculd be contained by piping integrity downstre1= of the isolation valve. The staff agreed that dcwnstrean integrity of Category 1 lines wculd be an acceptable barrier, hcwever, this is not applicable for other lines. The applicants stated that the fluid block system was not an engineered safety feature and that they do not receive credit for this system in evaluating potential radiological consequences of a LCCA (Regulatory Guide 1.4), or for meeting containment leakage requirements of Appendix J, 10 CFR Part 50. The applicants described their proposed design alternative to the fluid block system which they believe meets the intent, purpose and cbjectives of their PSAR ccmmitment. Those lines requiring isolation wculd be provided with cne of the typical valve arrangements shcwn in attached Sketches 1 through 4 to provide assurance that leaks to the environment are ALAP. The majority c? lines would use the concepts in Sketches 1, 3 and 4. The concept in Sketch 1 provides a barrier to stem leakage but net to seat or thrcugh-line leakage. The configuration in Sketch 2 is essentially the same as a typical arrangement presented in the PSAR with the exception that the use of a 81 220

. smaller local tank for the scurce of seal fluid of f ers reduced consequences of a single failure in the seal system. It is expected that only a few lines will utilize this configuration. The configurations in Sketches 3 and 4 offer an additional barrier against seat leakage as cc= pared to a two-valve arrangement withcut fluid block. The globe valve in Sketch 4 would be installed with the seat en the upstream side of the stem to minimize the possibility of stem leakage. The applicants indicated that application of these concepts would result in (1) improved overall performance through the use of gicbe valves in place of gate valves and under con-ditions of single failure, (2) decreased time interval required for isolation, (3) more cost effective implementation, and (4) minimal impact on construction scheduling. The staf f stated that it would be necessary to evaluate the cbjective of biccking only stem leakagt and stated the belief that the biccking of seat leakage m.ay have also been an original consideration in TMI-2. The staff also stated that it was important to understand how the preposed system compares with the TMI-l design (see Attachment 3). The applicants stated that they had been unsuccessful in estincting the differences in de es, with and without fluid block, to analy e the possible etfectiveness of the feature. They also stated that they believed TMI-2 to be significantly belcw Part 100, 10 CFR doses. The applicants' representatives stated that they will amend tha TMI-2 FSAR to include these alternatives to fluid block in the design. Althcugh the staff cannot evaluate the design until complete information is received, the staf f stated that they would try to identify specific concerns to the applicants on the basis of the information presented at this meeting. The applicants stated that they intend to submit their design and analysis on May 30, 1975. / f b. O , f f / ty'?& / /., s us-3. W. Wr.shburn, Project Manager Light Water Reacters Branch 2-2 Division of Reacter Licensing Inclosures: As stated 81~230

_C ?m e' 'i 1 : 'I D 2' " '" r - d m.u -.7 'l--. r e *.9 U - - s c.., CLV A A 'A e fLv Acril 17, 1975 Recm P-110 Name Affiliation Charles Ferrell NRC 3. Grimes NRC J. Kunkel GPUSC J. R. Moore GPUSC J. M. Vann GPUSC A. W. Hagstrca 3&R N. E. Lacy 3&R J. R. Ellwanger B&R A. F. Zallnick 3&R D. Shum NRC J. Shapaker NRC K. Kniel NRC:L 3. Washburn NRC:L Attachment i 81 231

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BACKGRCUND INFORMATION 1. Fluid Block Concepts at che Construction Permit Stage - TMI-2: The fluid block feature was cescribed briefly and incenpletely (as the Isolation Valve Seal Water System) in Section 5.3 of the PSAR. The design basis for this system was to improve the effectiveness of the containment isolaticn valves in the event of a less-of-ccolant accident by providing a water seal at isolation valves en lines which can communicate with the containment atmosphere. The system ficw diagram and typical seal water injection details are shown in Figure 5-10, Attachment 2 to the Meeting Summary. The PSAR isolation valve arrangements utilizing fluid block are shcwn in Figure 5-8, Attachment 3-A,and seal water inj ection was provided to those penetrations listed in Table 5-1, Attachment 3-B. The PSAR design evaluation discussion was incomplete in tha t it discussed seal water injection for the typical arrangement of two isolation points located cutside the containment boundary, Attachment 2, and did not specifi-cally address the evaluation for the split wedge isolation Lives. This design evaluation for the two-isolation point arr angement stated: 'The possibility of leakage f rom the containment or reacter ecolant system past the first isolation barrier is thus prevented by assuring that if leakage does exist, it will be frcm the seal water system into the containment." The above evaluation and sketch in Ficure 5-10 are interpreted to preclude both stem and seat (through-line) leakage cf containment atmosphere er reactor coolant. The design evaluation did not include discussion of the split wedge gate isolation valve seal water injection ieature_ hcwever, it is the staf f 's understanding that rhen water is inje:ted into the bonnet of this valve, at a pressure in excess of that inside the line, the 61~233 valve stem packing (bennet) and both seating surf aces within the valve body are sealed. (See, for example, Section 5.3.5.2, page 5-63, TMI-l FSAR, Decket Nc. 50-239.) It follows frcm this understanding that such fluid blocking ensures that any leakage past valve seats, stem packing and/or other closures is seal fluid. It follcws, frcm the PSAR design basis, evaluation and the above understanding of split wedge gate isolation valve features, th at the PSAR fluid blocking arrangements ensure that any leakage past valve seats, stem packing and/or other closures is seal fluid. 2. Leakage Control in the Proposed System - a. Sketch 1 Provides stem seal / prevents stem leakage Does not prevent seat or through-line leakage Uses globe valve outside containment, b. Sketch 2 Provides same leakage prevention as the PSAR design; incorporates fluid blocking concepts (concept can provide more diversity than the PSAR design). c. Sketches 3 and 4 Provides an additional mechanical seat (barrier) against through-line leakage as cc= pared to a two-valve arrangement without fluid bicek Dces not provide stem seal Dces not provide the same assurance as does fluid block f or through-line leakage. N.~22M 3. TMI-l Fluid 31cck Feature (FSAR) The report to the ACRS at the construction permit licensing stage states that the fluid block (or fluid seal) system was added by the applicant in recognition of the relatively high population density. The TMI-l fluid block system inserts air or water, following an isolation signal, into lines not required for post accident conditions. The system design ensures that these lines penetrating containment are pressurized with fluid to provide a seal against leakage of containment atmosphere to the environment during any condition requiring isolation. Where gate valves are used, water is injected into the valve bonnet. This seals the bennet (valve stem packing) and bcth seating surfaces within the valve bcdy. Where cicsures other than gate valves are used, air is injected into the line between the two closures. Two pressurized water tanks and two distribution headers are used. Instrument air is the normal pressurization source, plant service air is the backup source and the high pressure nitrogen system is the second backup. Design features prevent inadvertent fluid blocking of a normally open isolation valve and prevent fluid blockf e of an isolation valve that is not ccmpletely closed. The TMI-l design ensures that leakage past valve seats, stem packing and/or other closures is seal water or air and not containment atmosphere. The TMI-l fluid block feature is not an engineered safe-guards system and is subject to single failure.

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Table 5-1 kcattor Bullding Isolation Valvo Infore.ation renc-rios l ocat to.i

1. I no H thod Sval Nua na i l'ua l -

Valvo Poaltlun Acoldent tsution Diruc-Velve kolossed Valva $1se, of Watur No tes vis i Sy s. t ene t io.i Aargt. t u' H. II. ly g in. A r t.1.tlan lujeiclon S ippa l roattlon i n l l 8' a s t on ronillon ra ce ui le e r :;t c. CA Out 5 lustJe Cite 3/8 l'Ho

  • Na is CloucJ Yes Closed W.e t e s spesu Catu 3/8 t iid No IS Cluned Yea Cleaed ham.slu l.i ne n outetJa Cate 3/6 Air Aiet u tS CluncJ Yes Cl u:s ed 2

e. a t..r builJang Wu Out ) InstJe Cute 4 D10 Ne t.S ClueeJ Yes ClumwJ e (# Sin p rump Diottierge OutelJe Cate 4 Air Hanuel ts Closud Yes CluncJ p

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%D 1 Irt-tbun t. I n u to IIU Out 5 lustJo Catu 2-1/2" 1110 No DS Open Yue CluecJ be " l'ur t i lc a t t un b Cate 2-1/2 DIO Ho LS CluecJ Yes CluecJ "1 is minetaltruse

  • Oitelde Cete 2-1/2 Air Auto t' S Opun Yes Ci ne c.!

f.. - ~ ([- 4 Heuttor Cuolant Hu Out 5 luulJo Cute 4 t il0 No IS Open Yue ClouuJ P.nep Soel Water I n.e l J a Cato 1-1/2 Ltid Ne LS Open Yes Closed Mstuin LIne OutelJe Cate 4 Air Huuual LS Open Yue Clumed p.- 5 ucattur coulant Hu In InstJe Stop 1-1/2 --- No Open Na CluscJ ru*p Soel Water Ch. (- Supply OutelJe Capi? 4 J. a r Manuel 1hrottle Yom ClourJ** ) Cote 4 Hanwel Na C l ume.1 No ClueuJ 6 (Noimal Hukrop to HU In 2 Inside Chork 2-1/2 --- No Open No Open (sin Sometus Coulent out e lJe C l ut.u 2-1/2 Air No lbrotticJ Yes open [* (iyutom OutelJe Cluba I 2-1/2 Att ha sual ClueeJ Ho CluecJ vi 6*7'9 6 (Ill gh-l'a c e so r e HU In 7 Inside Clc(k 2-1/2 --- No Na Open i ".M - (injc(tlun Line Outelde Cote 2-1/2 til0 Hanual LS Cluurd Yes open 10.11 Fuel Transfer Tut.e SF In/0ot 8 Inside Special 30 No CluerJ CluecJ Clueure I outsida Cete 10 Hanuel No CloucJ Ho CloucJ o II Weactor BullJing DS In 7 Insida Ct.e c k 8 No =No open Spaay talet Line Oute!Je Cate ff 1HO Hanuel l's Clumed Vee - Open I-t1 _ u s 13 Hoactor building BS In 7 InstJe Cl.c c k 8 No No Open .p 3, tt hpsay Intut Lino OutetJo Cato 8 ttIO Hanual LS CloocJ Tce opun it 14 Decay lleet Cuolent bil In 7 InolJa Check 10 Na Clon J Ho open 9 hetuin OutetJa Cate 10 Ltio Aute l' S CloseJ Yes open [j g .15 Detey licat Coolent Dil in 7 I ns t J.: Check 10 No Closed No Open (D g Hetuin outelJe Cate 10 tito Auto IS CluecJ Tce open CD

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16 LJecay llent Cuolent Dil Out 9 InstJo Cate 18 Hanuel No CluncJ Na CloscJ N tetJoon Cate (2) 12 LtO No k ema.t e CluncJ Yes Clumed h Hanuel e W Oute1Je Cete 12 Ul0 Autc Rc=ote CloscJ Yes CluscJ y Hanual 17 Resetor Dut! Jing Dit out 10 OutetJe Cete 14 D10 Hanual Rs. mote Clueed Yes Open g gg Sump Hecisculation Hanuel line i 18 kenctur Dut1Jans DH Out 10 Outelde Cate 14 lito Manual k wie CloscJ Yes Open Sump pacttculation Henual Line I AI! velvce with electric actor operators are eleo egutpped with hand wheele

    • Pust-acclJent reactor coolant system pressure causes valve to close i

Table 5-1 (continued) rene-Flow locattua 1.Ine Hett.od Seal Normal Fuet- -{ tration Direc-Valve Refested Valve Sise of Water Valve Peeltlon AcctJent _NL _ _ S e g t r e,, System tion Ausgt. to R.B. Tyt in. Actuation M ection Sf,nel Position InJlceflon fontelon f 1 19 Reector Cuolant Wu Out 14 uutelde Cate 2 Air Auto LS CloscJ Yes CloscJ Drain Tank Vent y h 20,21 licact or Bu11Ja ng la 11 InstJa Butterfly'36" Did No ES CloseJ Yes Closed Inlet Purge Line OutelJe Butterfly 36" Air Na LS Closed Yes Clueed g 22,23 Reactor BullJing Out 12 Inside Butterfly 36" im No ES CloucJ Yta CloacJ Outlet l'u 6 ge 1.t ne Outeld: Butterfly 3t" Air No LS Closed Yes CluscJ { 24,25 Itcoce s,r Coulant SW In/Out 6 Outelua Cate 8" D10 Hanual LS Open Yes Closed 3 Pu=p Notors and tube Oute!Je Cate 8" Lito Hanual ES Open Yes CloucJ 011 Coolers 26.27 Aunillany recJuster in 13 Outelde Cate 6" uto No Closed Yes CloncJ V \\ In 13, Out elJe Stopclinck 2n" .A l t No Open No Closed 2 *., 2 9 Fe(Jsater Lluce 5 30-33 Steam 1.inen Out 13 Outelde cate 28 IlyJ r. No ES Open Yes Closed 34, M Stes.e Cencratur CA Out 3 InstJe Cote 3/8 kJ10 No Remote Open Yes CluscJ Sampic 1.ine H.uiv a l Outelde Cato 3/8 EN0 Auto LS Open Yes CluecJ T,_. 36,37 Cosa Floo.llnA Tank Hb4N In 4 Inoldo Clicck 1 No Cluned No Cloac.) Fill & Nittogen OutalJa Check 1 Auto Closed No CloncJ Supply 1ine 38 Reat.tur Coolant Wu out S Insida Cote 4" DIO Na LS CloscJ Yes CiencJ Syeic. Drain 1.ine No ES CloscJ Yes Cluard ou t e l.la Cate 4 Air Auto 1.5 CloscJ Yes CloacJ 39,40 IntermcJinte Inmida Clicck 6 No Open No Cinacd g g 4 Coull**d % = tem outside Check 6 Hanual Open No CloacJ InnlJo Cate 6 LHO Ho ES Open Yes CluacJ Out 3 Outelde Cate 6 Air Hanual' LS Open Yes CloncJ 41 Contrul kod prive 5W In/Out 6 Inside Check 4" No Open No CloncJ Coollog Water Supply Outelde Glotes 4 Air No 'lle r o t t l e Yes Clo.cd 42 Control koJ Drive SW Couting Water Supply N 43 Fuel 1ranafer Canal SF Out l$ Inside Cate 10" Hainaal No CloneJ Ho CluacJ I kocliculation 1. loc outelde Cate 10" Honual Hanual CloscJ Ho CloucJ M Cote 10" Hanual Manunt C l ue.cd No Cleard 44 Cosu F i n.i.l i n ut T.uik CA out 5 Inoldo Cate 3/8" So l e no t.1 Hanual tiemat e CloscJ Yes Cloard Sample f.ls.n Hanual 45 Cuto Floo.llna 1ank WD 3 1" Solenold Hanual Hen.ote Cl eed Yen C l o s e.1 Sampic niccJ 1Inc Nanu.il Outelde Cate 1/2 Solenoid Hannal Ifi Cinecd Yes Cloacil 46-30 henctor liullJina kW lif/Out 6 OutelJo Cote 10" Alr No 3-open Yes oan r Imragen y Air C.olore 2-CloncJ 50 55 14 c a c t o t liu l l.l l n g HW In/Out 6 Ou t u l.a n Cate 10" .Alr No 3.open Yen Dee n 1 -.. c..s. y a.

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April 22, 1975 DOCKET NO: 50-32'I APPLICANTS: Metropclitea Edison Company Jersey Ce: tral Power & Light Company Pennsy1.vania Electric Ccmpany Three Mile Island Nuclear Station, Unit 2 FACILITY: APRIL 17, 1975, WITH METROPOLITAN EDISON SUM'4ARY OF MEETING, COMPANY TO DISCUSS CONTAINMENT ISOLATION FEATURES FOR THREE MILE ISLAND NUCLEAR STATION, U'iIT 2 (TMI-2) in Bethesda, Members of the Nuclear Reactor Regulation staf f met 1975, with representatives of MetropoaA-Maryland, on April 17, tan Edison Company to discuss alternatives to fluid blocking ior lines penetrating the containment in T5t:-2. Backcround_ The TMI-2 Preliminary Safety Ana3 fsis Report (PSAR) and the construction permit (CP) hearing record included a commitment by the applicants to incorporate a fluid blocking or isolation final design of the plant. The - valve seal water feature in the the purpose of this feature was to improve the ef^ectiveness of isolation valves by providing a fluid seal in lines containment which could communicate with the containment atmosphere and to under accident insure low leakage rates from the contain:nent conditions. This feature had not been retained in the final design when the FSAal Safety Analysis Report (FSAR) for T'1I-2 vss filed. The Atomic Energy Ccmmission regulatory s caf f reviewed the d the information in the Three Mile Island dockets and advise applicants by letter dated April 25, 1974, that this feature should be retained in the design for TMI-2. The applicants' letter of May 29, 1974, submitted undated information cencerning diffusion meteorology and proposed to delete this feature on the basis of more favorable existing v.etecrological conditions than were used during the earlier sire studies. r( t- / .m/ s if fpl. . 2 LW3)dsnNzs _ Q,j .'.f E. cp pg2,2 c=* w a rriss-gjaao.axer xxniel [/ y) ....e... y m m /.(4 /j/. 7 5.. .+. / / 7 5 ,,e,,, - //19/75 4/f}/75 n W u. s. novan=essNr pasunne oretcan ina.sse-s ee Fwm AIC.318 Ote'. 9-5 5) AECM 0240

01s cu s s_i_e. r. Tne applicants revie.ied the PSAR concept of the fluic cicci feature and its disauvantaces. The PSA2 cencepcual lesig:. anf typical valve arrangenents are given ir. Figcre 5-l' (Attachnent 2). The applicants stated that a lack of redundancv in the original flu;_ block header concept nade it sasen,tihl2 to single break failure, valve failure could ficed the centain-ment during normal tperation and the carbon ctael system is unsuited for use with borated water as the blcching fluid. The acplicants stated that tha intention of the PS.3E flull block feature was tc elininata only valve stem leakace (see ) in the event that valve p;cking le.1ks were present and that sten leakage was more i'.ncrtant t".an cent leakage sinca seat leakage would be contained by pipin7 integrity downstream of the isolation valve. The staff agreed that dcwnstream integrity of Category 1 lines '. culd be an acceptable barrier, however, this is not applicable for other lines. The applicants stated that the fluid bicck system wac not an engineered cafety feature and tnat they do not receive credit fcr h31s system in evaluating pctential radiological consecuences of a LOCA (Regulatory Guide 1.4), or for T.ectinc containment icahage requirc=ents of Appendix J, 10 CFP. Part 50. The applicants described their proposed design alternative to the fluid bicch system which they believe meets the intent, purppse and cLjectives of their PaAR connitnent. Those lines requiring isolation wculd be provided with cac of the ty ical valve arrangements shown in attached Sketches 1 throu7h 4 to provide assurance that leaks to the environment are ALAP. The majority of lines would use the enccapts in Sketches 1, 3 and 4. The concept in Sketch 1 provides a barrier to stec leakage but not to seat or through-line leakage. The ecnficuration in Shetch 2 is essentially the same as a typical arrangement presented in the PSAR with the exception that the use cf a u' **C E * ..'". l}. s v== = = a

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. smaller local tank fer the scurce of seal fluid offers reduced consequencas of 4 single failure in tne seal system. It is expected that only a few lines will utilize this configura tio n. The configurations in Sketches 3 and 4 offer an additional barrier against seat leakage as conpared to a two-valve arrangement without fluid block. The globe valve in Sketch 4 would be installed with the seat on the upstrean side of the ster to c.inimire the possibility of stem le akace. The applicants indicated that application of there ccacerts veuld result in (1) improved overall performance through the use of globe valves in clace of gate valves and under con-ditions of sincle failure, (2) decreased tire inter 131 required for inclation, (3) nore cost ef fective implenentation, and (4) minimal impact on construction scheduling. The staff stated that it wculd be necessary to evaluate the objective of blocking only stem leakage and stated the belief daat the blecking of seat leakage may have also been an original consideration in TMI-2. The staff also stated thct it was important to understand how the proposed system ccmpares with the TMI-l design (see Attachment 3). The applicants stated tha.t they had been unsuccassful in estimating the differences in deees, with and without fluid block, to analy o the possible effectiveneus of the f eature. They also stated that they believed TMI-2 to be significantly below Part 100, 10 CFR doses. The applicants' representatives stated that they will anend the T3I-2 FSAR to include these alternatives to fluid block in the design. Although the staff cannot evaluato the desian until ccmplete information is received, the staf f stated that they would try to identify specific concerns to the applicants en the basia of the information presented at this meeting. The applicants s':ated that they intend to submit their design and analysis on May 30, 1975. lf $,'YVb 7,bV tT E. W. Washburn, Project Manager Light Water Reacters Branc. 2-2 Division of Reactor Licensinc Encicsures: As s.tatec opeen

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re Affiliation Charles Ferrell NRC B. Grimes MPC J.

Kt:nkel GPUSC J. R. Moore GPUSC J. M. Vann GPUSC A. W. Hagstrom B&R N. H. Lacy Bt* J. R. Ellwanger B&R A. F. Zallnick B&R D. Shum MRC J. Shapaker NRC K. Kniel NRC:L ~fashburn NRC:L B. r Attachr.ent 1 ..- - 8 1 -243 aa,s. Form A EC 31 s ( Re,. 9-3 3 ) AECM 0240

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s 1. Fluid Elech Ccncepts at the Ocnstructio. *2ermit State - TMI-2: The fluid block feature was described briefly and inccapletely (as the Isclation valve Seni riater System) in Section 5.3 of the PSAR. The design basis for this systen was to innreve the effectiveness cf the containment isclaticn valves 1 -' the event of a loss-of-ccclant accident by providini a water seal at isolation valueesen lincs which can con:nunicate with the centainmen at-csphere. The system flow diagram and tyrical seal water injectie-details are shown in Figure 5-10, Attachr.cnt 2 to the Meeting Su: ary. The PSAR isolaticn valve arrangements utilizing fluid block are shown dn FiTure 5-9, Attachnent 3-A,and seal water injecticn wasf Pc"tYo%e penetrations listed in Table 5-1, Attachment 3-3. The PSAR design evaluaticn discussion was incc plate in that it discussed seal water injection for the typical arrangement of t.io isolatica points 1ccated cutside the containment boundary, Attachment 2, and did not specifi-cally address the evaluation for the split wedce isolation valves. This design evaluation for the two-isolation point arrangement stated: "The possibility cf leakage from the containment er reactor ecolant s'fsten past the first isolatien barrior is thus prevented by assuring that if leakage does exist, it will be fren the seal water system into the containment. " The abcve evaluation and sketch in Figure 5-10 are interpreted to preclude both stem and seat ( through-line ) leakage of containment atmosphere er reactor coolant. The design evaluation did not include discussion of the split wedge gate isolation valve seal water injection feature, hcwever, it is the staff's understanding that when water is injected into the bonnat of this valve, at a pressure in excess of that inside the line, the a::a c.,.,e n t 2 ,o... [. 81..._.2..44.. rm rc m sia,s u s, 41c.w m a en '. n a- ' u= > -

9 e valve ste:. packing (bonne t) and both saatinc surfaces wicain the valfe body are scaled. (doe, fcr ex rple, Fection 3.3.5.2, pace 5-63, TV.I-l FSAP, Oceket *:c. 30-259.) It follows f.hom this uncerstandinc that such fluid ulecking ensure: that any leaka te past valve seats, atem packing and/or other clcsurea is seal fluid. It follows, from the PSAR design basis, evaluation and the above understandinc of split wedge gate isolatien valve features, th at the PSAR fluid bleching arrancerents ensure that any leakame past valve seats, stem cackinc and/or other closures is seal fluid. 2. Leakage Control in the Preposed Svste-' - a. Sketch 1 Provides sten seal / prevents stem leakage Docs not prevent seat or through-line leakage Uses globe valve outside containment. b. Sketch 2 Provides same leakage prevention as the PSAR desigr-incorporates f]uid blocking concepts (concept can provide more diversity than the PSAR design). c. Sketches 3 and 4 Provides an additional mechanical seat (barrier) ar;ains t through-line leakace as compared to a two-valve arra..msment without fluid block Dces not provi.de stem seal Does not prov!de the sane assurance as does fluid block for thr> ugh-line leakace. O F'M t

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i-talve bon-.et. This sealc the bcnnet (valve ste" nackinc) and ~ cth seating surf aces within the valve bcdy. Mhera closures other than gate vr.1"es are used, air is injecte,' into the line between the two closu e,. Two pressurized water tan %s and two distribution headers are used. Instrunent air is the ner.a1 pressurization scurce, plant service air is the hackup source and t".c high pressure nitrogen systen is the second 'cackup. Design features prevent inadvertent fluid blocking of a nornally open isolation valve and - revent fluid blockinc L of an isolation valve that is not cenpletely closed. The TMI-l design ensures that leakace past valve seats, stem packing and/or other closures is seal water er air and not containment atmosphere. The TMI-l fluid block feature is not an engineered safe-guards systec and is subject to single failure. However. the fluin block tanks, process piping and valves are Seismic Class I. l ....u ... 4. . 81-246 C4YE .uc.m a. 4.,3,.uc.- - ~........ -

ITINC SUMMA 2Y DISTRI3UTION Docket No. 50-320 Metropolitan Edison Ccepany Metropolitan Edison Company George F. Trowbridge, Esquire ATTN: Mr. R. C. Arnold Shaw, Pittman, Potts & Trowbridge Vice President 910 17th S treet, N. W. P. O. Box 542 'Jashington, D. C. 2C006 Reading, Pennsylvania 19603 Mr. Thomas M. Cri== ins, Jr. Mr. Richard W. Heward Safety and Licensing Manager Project Manager GPU Service Corporation G7U Service Corporation 260 Cherry Hill Road 260 Cherry Hill Road Parsippany, New Jersey 07054 Parsippany, New Jersey 07054 Chauncey R. Kepf ord, Esquire Chair:an York Cetrittee for a Safe Environ =ent General Delivery York, Pennsylvania 17401 Docket File O. Parr A. Schwencer NRC POR Local PDR R. Schemel NRR Reading D. Ziemann LWR 2-2 Reading P. Collins R. Maccary G. Knighton V. Stello G. Dicker R. L. T2desco B. Youngblood H. Denton W. Regan J. Knight S. Varga

5. Pawlicki M. Williams L. Shao R. Klecker T. Nosak F. Schroeder D. Ross EP Project Manager R. Ecuston Project Manager T. Ippolito ELD C. Long IE (3)

G. Lainas M. Service V. Benaraya ACRS (14)

3. Grizes D. Muller W. Ca==ill W. Butler J. Kastner

.J. Stol: M. Spangler R. Clark R. 3allard T. Speis V. Moore D. Vassallo R. DeYourg K. 7,iel D. Skovhol 81 247}}

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