ML19312D216

Forwards Addl Info Re Containment Purge & Vent Sys.Describes Initiation of Containment Isolation,Instrumentation & Control Sys & Radiation Monitors.Drawings Available in Central Files Only

ML19312D216
Person / Time
Site:	Prairie Island
Issue date:	03/17/1980
From:	Mayer L NORTHERN STATES POWER CO.
To:	Office of Nuclear Reactor Regulation
Shared Package
ML19271A357	List: ML19312D216
References
NUDOCS 8003210530
Download: ML19312D216 (9)

Text

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V NSF NORTHERN S T A T E'S POWER COMPANY MIN N E APOLI S. MIN N E SOTA 55401 )

March 17,1980 l

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Director of Nuclear Reactor Regulation l U S Nuclear Regulatory Commission  !

Washington, DC 20555 l PRAIRIE ISLAND NUCLEAR GENERATING PLANT l Docket Nos. 50-282. License Nos. Di'R-42 l 50-306 DPR-60 i I

Additional Information Concerning Containment Purge and Vent System l 1

In ~a- letter dated January 9,1980 from A Schwencer,- Chief, Operating Reacters Branch #1, Division of Operating Reactors, USNRC, we' were asked to j supply additional information related to the NRC Staff's ongoing review of problems associated with containment venting and purging. Information l requested in the enclosure to Mr Schwencer's letter is contained in Enclo- I sure (1). '

Enclosure (2) contains a comparison of the' Prairie Island containment purge and vent system design to NRC Branch Technical Position CSB 6-4. This comparison was requested during a telephone- conversation with Mr M Grotenhuis ,

Project Manager, Operating Reactors Branch #1, USNRC, Please contact us if you have any questions related to the information we have provided.

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L O.Mayer, PE Manager of Nuclear Support Services LOM/DMM/jh 1

cc J G.Keppler I G Charnof f - l Enclos ures r l

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qDirector'of NRR,- USNRC March-17, 1980

Enclos'ure ' (1)?

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Response to Request for Additional Information Contained in

<_ Mr Schwencer's Letter dated January 9,1980 Item 1

1. Containment Isolation (CI)--is~ initiated manually or by a Safety Injec-tion (SI) signal-which is generated. by high containment pressure, low press.urizer: pressure, or low steam line pre's sure. In addition, a high radiation level in the containment or ventilation-system ducting is used as a diverse parameter for automatic Containment Ventilation Isolation (CVI). ' Manual containment spray (CS) initiation also initiates CVI. JControls are provided to override each train of CI, 'SI, and CVI logic.

Reset of SI-(override) will'not defeat the ability- of high radiation, manual.CI,'or manual CS to actuate'CVI or'the ability of manual CI to

' actuate-CI.

Reset of CVI .(override), when CVI . is initiated from SI or high radiation signals, utilizes a seal-in circuit. The reset will rema'in until the initiating signal is ~ removed l(SI is reset, or-the radiation level falls below the high level setpoint). During the period that CVI is in reset and the initiating signal remains, the other signals will be blocked from initiat'ing CVI. CI, SI, and radiation monitor reset (override) also' utilize this seal-in feature.

2. Key lock switches were not provided in the plant design.

3. ' Annunciation in the control. room of override status exists for SI reset (override), but not for CI reset'(override), CVI reset (override), or

'the radiation monitors providing an input to CVI.

3.c CVI is initiated through the SI' network by containment pressure, pressurizer pressure,'or ste'am line pressure; by high containment radiation;.or'is manually ~ initiated.

5.. The instrumentation an'd control systems required to initiate the

' Engineered Safeguards System (ESP) a're designed and qualified as safety-grade equipment.

'6.- The overriding _ or resetting of f isolation actuation signais does not cause' automatic reposition of any ESF isolation valve or damper.

Overriding or resetting merely permits valve 'or damper repositioning by 7 manual-control switch operation.

Item 2

_ Fourf sets of process :and instrumentation and schematic drawing's ofor the .

LPrairie Island purge 'and vent system and control room heating, ventilation, and" air:conditior.ing system are enclosed.

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$CVIjis initiated ~uponVa h'igh c'ontainmentipressure condition through the SI'

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. . . . Radiation monitors req'uired toi.'in! .iate !CVI' are . safety-grade equipment.

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Director of NRR,'USNRC_ *

. Enclosure;(2)- ~

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Response.toDRequest l for Additibn Information"Re'ceivedl by Telephone

- from M Grotenhuis, Project Manager, Operating Reactors Branch #1, . USNRC NRC Request

,p l Provide a description of the containment purge .and'. vent system, demonstrating

-that theide' sign'of thialsystem satisfies _ the requirements. of- the NRC Branch Technica1' Position CSB' 6-4, Rev 1, " Containment Purging During . Normal Plant 70peration"." DYour . respo'nse'should address each paragraph and .sub paragraph

'of the Branch Technical; Position, with the exception: of sub paragraphs if,

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^ and Sc which were1 addressed in your. submittal dated April 12,.1979.

.. Response -

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' Tne Prairie Island Con;ainmen't Purge System and Contal'nment Inservice Purge System are described in Sectlon 5.4 ' of c the Final Safety Analysis Report (FSAR).. Flow' diagress for these. systems .are enclosed.

- Thefattached table provides a' point-by point . comparison of the Prairie ~

Island de' sign'to Branch Technical Position CSB.6-4,. Revision ,1. The iPrairie Island'~ design predates CSB 6-4'and does"not conform in all respects.

We believe , however, that -the ' areas of departure ' from the recommendations -

.of CSB 6-4;have 11ttle' or 'nof safety. significance and are acceptable. . Where indicated,; additional' analyses 'will be completed and submitted for review.

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GPRAIRIE? ISLAND .00NTAlletErr PURGE : AND VENT. SYSTEM;.. '

Enclosure'(2)/ s' .

, - - R CMtPARISON WITH BRANCH: TECHNICAL' POSITION CSB76-4.

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' MRC Pos ition - n' b .

PrairietIsland System Description ~ (Remarks 1 g' n ,

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? iiTha[ system used[toLpurgeithe ;contaimsents for. the :- (Two',systeestare provide'dj the2Contain '- i ' ' '

rsactor; operational mSdeslof i power ' operation,': ment . Purgen Sys, tem :(33,000 lcfe) used L dur- : , ' '

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setcrtup,1 hotistandb'y andl hotishutdown; :i.e. 1 thel L ;ing shutdown and the Containment In - _

lt ;4ca-line purge (system,ishould belindependent; oft service. Purge System (4',000 cfm)'usedi 2 ,

. : thO purge [ system used for. the- reactor; operational. :during power operation. .. ^

. R aodeslof; cold J shutdown J and ' re fueling.1 EliiThe on-lineLpurge: system lshould:be designed ~

iniaccosdance withlthe ;following cratertai i

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a. lhe: performanc'e ; and, reliability off the,- Theilnservice Purge System'! valves werel Environmenta1' qualification ofi purge' system isolation; valves:should be:

.provided:asl safety grade-equipment. 'the isolation valves: located; y j consis.tentivith)the' operability assurane Ttie. valves have;been tested ~to confirm 'inside! containment'is undergoing?

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r f program outlined;in MEB: Branch: Technicall they can withstiand the necessary earth-' review as required by IE Bulle-:

"PositionDB-2, Pump 'and Valve ' Operability ~ quakefloading. . -. t in~ 79-1B.1

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l I Assurance Program.- (Also see SRP Sect ton 3.9.3.)fETheldesign basis 1for the valves- ' h e' valve' vendor _is. analyzing they hand'.actuatorsfshouldcinclude the buildupf ' valves for" loads . associated with.

D (of:Leontainment ' pressure fort the LOCA; closure duringlLOCA.: Refer'to

, break'.s'pectrum,;and the; purge linefand~ -an NSP letter dated November 14 - ,

7 (vent lline'.- flows as a : function. of time up, 1979. he results 'of thisi q -

to;and during valve, closure. analysis 1willLbe submitted.for- j!

.NRC Staff review - ,,-

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I w c b. ;;The [ni=her, of. purge and vent lines -

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? Each contaissent has one supply and that may be used should be 1imited i

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exhaust line a~ssoc.iated with the' to, one : purge linel and 'oneLvent line'. .

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Inservice Purge System. '

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c.y The'. size of; the purge' and .venta lines : Eighteen-inch su'p ply and exhaust' lines . 'Anf analysi's will be performed should :notlexceed Labout eight inches .in Twere :specified lin the ' original ; plant: to. confirm thatlthe radiological-

diame ter unle s s Lde tailed ) jus t i ficat i6a . design. consequences following LOCA -willL forflarger/line lsise's is .provided, g be within .10 CFR Part 100 guide

. . lines. 'Results'will.be submitted.

. . for NRC Staf f review.

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l March1 17 F1980 : _' , PRAIRIE I ISLAND LCONIAIIt!ENT PURGE . AND VENT ~ SYSTEM

, . Enclosure'j (2);(Cont!inued)j M" JCOMPARISON WITH-BRANCH TECHNICAL POSITION'CSB'6  : Page12 fof?57 (NRC Pesstion 7 [ Prairie Island System Description Rema rk's '*

- ~ ,d.- The' containment ^ isolation. provisions for? ' Contairunent' isolations provisions -

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the purge system 1ines: should 'me'etl the . , meet 1 safeguards criteriaof quality,

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_ standards T appropria'te;tofengineered6

' redundancy,ftestability,OandLother s'afety; feature's ; i.e.,' quality, redunlancy, apiropriate' i criteria, ,

testability land:other appropriate criteria. -

ie.:..' Ins'trumentation and control; systems pro- -

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" Isolation occurs on high contairunent.

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vided to' isolate.the purge' system: lines  : pressure, low pressurizer pressure, .

g ' ;should;be independent and. actuated;by; ilow steam' line pressure, or high..

diverse l parame ters ; L e.g. , containsment .- icontainment radiation (gaseous or?

- pressure, safety injection ' actuation, particulate). . Valves fail clo' sed '

and contatament-radiation level. 'If -on loss of motive air or- solenoid t energy;? is : required' to' close 'the valves, . valve power, ,

Jatoleast' two diverse sources ' of energy -

shall;be .provided,f either of which cane 1 af fect ' the isolation functio'n.

if. Purgeisystem isolation valve closure iValue closure time is less than three

' times, including instrumentation delays, seconds =by design.

should' not' exceed; five seconds.

. 'g. fProvisions:should be made,to ensure , No; provisions were made in the Ethat' isolation' valve closure will not  ; original: plant design to prevent ~

be' prevented by debris whichicould . debris'which could potentially potentially ecome entrained lin the .become entrained in the. escaping escaping air and steam. -air-stream mixture from entering a containment pur2e or , vent line.-

Esch line is provided with two butter -

i. -fly-type valves.

f :There is_little likelihood that -

debris.could prevent both valves from closing' tightly. ,

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m March 117, .l1980 " , , l PRAIRIE 1 ISLAND CONIAIl9 TENT.PURCE-AND VENT SYSTEM; - ,'

l Enclosure ,(2 E(Continued)l , ' 1 OJMPARISON WITH BRANCH TECHNICAL POSITION - CSE 6-4' '

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q l MRC Pos it ion '.

• Prairie Island Systes' Description- Remarks

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( )!2.;. ;hk purge Esysten. should not' be relied on . for .: O t

The : pruge sys ten 'is ;not 1 relied; on !for .

i < 9 temperature / and humidity; control lwithin the . l temperature - or humidity. control.

containeentE

53. . I Provis[ons ish'ould, be ' made) to 1mininize the: need A-cleanup system consisting of-two

" A .for purging ofi thef containment bylproviding_ PAC units- (non-safeguards grade) is 5 s

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containment . atmosphere cleanup:within the ~  :.. provided in each containment. '

i cont'ainmenti 1

4. : $ Provisions., should be made fori testing the , Operability tests can be performed;

~' davailability.of'the. isolation function- at any time.:. 14akage rate.' measure-Dand '.the? leakage - rate ? of. the : isolation , cuents can'be obtained only;by- .

valves, individually, during: reactor testing valvesrin pairs. . ..,

' operation.

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51 Dh e-followinglanalyses,should be performed-

. ito ; justify the containment < purge' system l design:'~

xt fa.. Ananalysisoftheradiological(con-' IDCA dose calculations . assuming con-~ We will Lperform thelrequestied F sequences ' of J a , los s-of-coolant! accident .

. .tainment-Inservice Purge 1 is in pro- analysis..,Results'will be"sub .

T he analysis 'should be' done : for z a spectrum gress have not been performed in the mitted for NRC Staff review..

, of breakisizes, and thefinstrumentation' . detail requested in~.5(a)~. ,

i Land setpoints"that wi111 actuate.the vent "

and: purge.jalves. closed should_be 4 identified. ' h e: source term:used ir: the-i.. . radiological: calculations should be

. '. based; on a calculation under the terms of Appendix K ;to determine the extent

'of fuel. failure and'the concomitant.

i. release of fission products,Jand the .;

fissionDproduct: activity in;the primary

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icoolant. A pre-existing iodine spike ~

, should be. considered'in determining: primary coolantiact ivity, he; volume _of con-f

'tairsmentnin which fission products are h

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- N-2 March 117,u1980

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_ .., 'l PRAIRIE ISLAND CONTAlltfENT ~ PURGE - AND. VENT. SYSTEM '

. Encipsare J (2).:(Continued)', ~ COMPARISON WITH BRANCH TECHNICAL POSITION' CSB 6-4;

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C[NRC Position-- Prairie Island System' Description ' Remarks > > X

.; mixed should be. justified. . and the Ifission -

n' [ pEoducts]from the aboveisources should.be' releasedithrough;-the 'open purge . valves .

2 during? the maximum interval. required'for

valve closurel . the' radiological con-;- <

sequences :should be within 10. CFR 100 '

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f guideline' values.

- b. IAn aralys'is? which ' demonstratesithe accept- A11 ducting outside isolation valves

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ability of-thelprovisions made to protect- -in each supply and. exhaust lineir

' structures and ' safety-related equipment; J

l constructed of theavy gage sheet metal.

.e.g. , ;fans .' filters 'andiductwork. located - - This ducting .would ~ be' damaged in 'the '

cbeyondit he purgelsystem' isolation valves; event: of contaiwent pressurization

against'. loss}of

function from 'the environ , greater than.one v two psi if the ment created by;the escaping; air:and steam, inservice purge. system'were in use.:

The extent'of the' damage,to ducting.

will most likely.be limited to blowing -

out'of,the'section'immediately adjacent 4 -

to the containsent penet ra t ion'. ' Impinge'-

ment, heat, or moisture damage. to safety

, ~ related equipment in the . Auxiliary

' Building due to steam and air released in the three' seconds' required:to close the valves is unlikely.

1  ; c. [An analysis.of the reduction in the con - 'This analysis was completediand sub-tainnment ' pressure result ing fron'the mitted to the NRC on. April'12, ~ 1979.

. the, partial" loss of containment'

_ atmosphere ' during the accident for ECCS

' backpressure determination.

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,- March 117,21980 : l PRAIRIE-ISLAND CONTAIl#1ENT! PURGE AND. VENT' SYSTEM: -

Enclosuref(2) '(Co' ntinued);--

~

~' COMPARISON WITH BRANCH TECHNICAL POSITION CSB 6 Page: 5.of Sy NRC Position Prairie.-Island System Description' Remarks" ,

. d.NThe: allowable' le'ak' rates SfI- the purge .: LeaPage : test J procedures: and ' acceptance :

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and.: vent cisolation ~ valves' should be < criteria . conform to .10 CFR Part 50,..

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- 'specified f for ,the . spectrum 'of.. design .

' Appendix J. :All. tests are done at;the

- basis. pressures. ~and flows against which . maximum calculated containment pressure-

~ the' valves mustLclose.- ;of 46 psig. .These conditions are be-1 .

J.lieved co represent the most. severe (with regard to ~ leak tightness) ~ con- . ~

. ditions ' the valves' will experience.

The need for'other tests or ' leakage .

criteria has not been' established.

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