ML20037B557

Informs That NRC Is Continuing Review of ECCS Performance & Determined That Addl Info Requested in Encl Is Necessary. Info Requested by 760531 to Aid in Review Schedule

ML20037B557
Person / Time
Site:	Dresden
Issue date:	04/26/1976
From:	Ziemann D Office of Nuclear Reactor Regulation
To:	Bolger R COMMONWEALTH EDISON CO.
Shared Package
ML20037B556	List: ML20037B555 ML20037B557
References
NUDOCS 8010170728
Download: ML20037B557 (12)

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APR it.jg7g NRC PDR VStell'o Local PDR RBaer

,NDocket ASchwencer ORB #2 Reading Dockst No. 50-10 KRGoller i...:- ~ ~.._

.te TJCarter OELD - Swanson

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OIGE (3)

Corronwealth Edison Company DLZiemann

. ATTN: Mr. R. L. holger h'EConverse g.

Assistant Vice President M iggs Post Office box 767 DEisenhut t;;

Chicago, Illinois 60690 TBAbernathy b

JRBuchanan Centles:ren:

ACRS (16)

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>:e are continuing our review of the Dresden Unit No.1 emergency core cooling system (ECCS) performance with respect to the requirencnts of

g39 10 CFR 50.46 and have determined that the additional information requested

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in the attached Enclosures A and B is necessary to continue our review.

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Your responso should address the operation of the Dresden Unit No. I plant utilizing the proposed high pressure coolant injection system and other proposed ECCS r.odifications. Although the scope of the enclosed g

questions is broad, thorough answers on your part will clininate the t..

necessity for further information requests.

Five copies of requested f

large scale piping and instrumentation diagrams and of requested elec-

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trical diagrams should be submitted.with your reply. Where applicable, l

the enclosed questions may be answered by reference to previous submittals if that subnittal provides a sufficient answer to include the scope of the caclosed questions.

To enabic us to maintain our review schedulo, please submit the requested infort ation by May 31, 1976.

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Gincerely, Drt".na'l S55ned by:

. ;c.i.1 I.. Zie:. ann Dennis L. Zicn: ann, Chief

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Operating Reactors Branch #2 Division of Operating Reactors

Enclosures:

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A;C - Requests for

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l ENCIDGURE A COMMONWEALUI EDISON COMPANY

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DRESDEN UNIT NO.1 DOCKET NO. 50-10 REVIEW OF ECCS 5E=E:

REQUEST FOR ADDITIONAL INFORMATION

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1. a.

Identify all systems whose operation is essential to assure

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core. cooling or whose coeration is essential to insure operation I:i mi of those systems that do provide core cooling following a LOCA b.==-

for both short and long term cooling.

For example, it is not clear whether or not the service water, river water, or cooling water systems are essential.

Indicate the' safety and seismic

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classification of all parts of these systems, including all control, power, and hydraulic equipment essential to the operation

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b.

Provide a list of all pumps which can supply cooling water directly to s

the core, and all pumps which are necessary to supply cooling water

_.s m-to ECCS or related essential equipment (i.e. diesel cooling water,

[!l..=Em heat exchanger cooling water, seal water to pumps, etc.).

Indicate their pressure - flow characteristics, their water sources, their b:

safety and seismic classification, and their sources of power,

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specifying whether or not they can operate with power supplied i

only by on-site dier,el generators 1A or 1B or both, What is the capacity of,the Fire Pump, the Screen Wash Pump,' the-c.

two Well Pumps, and the Jockey Pump? Can these pumps be run from onsite(diesel) power?

If so, can each of the pumps be supplied n.

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from either diesel 1A or 1B (i.e. will failure of one diesel E

incapacitate all pumps if offsite power is lost).

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Provide a list of all valves (motor or air operated) whose functioning

h. 7 is necessary for any mode of ECCS operation including operation rll:

of all related essential equioment.

State the safety and Is:

seismic classification of the valve and its installation.

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State whether the valve is air operated (AO), motor operated

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using on-site diesels (MOD), or motor operated using on-site h

batteries (MOB). Also state whether A0 valves can be operated b

with loss of air supply.

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Provide material to update the P&ID's (that were provided in l

' answer to our recent January 26, ig76 questions) for those 2.._

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essential systems identifid.in Q1.

Those PalD's in many cases g

do not represent the plant as it will be following completion of 9.3 h

your current "HPCI modifications" and exoiration of your current

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exemption from the' requirements of Appendix K.

For example: - -- -

b [ ~~ I a. The fire system shows no inter-connection to the Dresden 2/3 system, nor was a P&ID of the Unit 2/3 fire system provided. g:; 3 ,? 3 b. Where does CS-101-8"-LX come from, as shown on M-595 (i.e.e A what are the other sources of water to the core spray

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system). 5 "j.) i.'I"?.. The fire water system P&ID doe's not"show where the supplf c. tap to the core spray system is located. ._ ~. L;; 37-Provide the results of a comprehensive single failure analysis-(Failure Modes and Effects Analysis - FMEA) performed for the Dresden 1 plant for which ECCS calculations are presented in i Table 3, August,1975 Appendix K With HPCI Modification Report. p3. e f -. . Include all credible failures in the systems identified in Q1.. ^ This s'tudy'~should be for the plant as it will be following ti. completion of HPCI installation and expiration of current exemptions ~ from certain requiretents of Appendix K, and must be sufficiently complete to insure that the worst active or passive electrical E.,g. or active mech.Inical single failure was assumed to have occurred E for each break size and location reported in the referenced Table 3. ~ The FMEA should be performed and presented in a manner similai-to p that performed for the Oyster Creek Muclear Generating Station E (JCP&L - OC NGS Single Failure Analysis - ECCS System, June 24, 1975 W=' and Revision 1 July 15,1975). This analysis should clearly state the. criteria'used in determining which single failures were r, assumed to occur concurrent with a LOCA, including a discussion of E I the items listed below. Additional information regarding single failures in electrical, instrumentation and control systems is [===~, requested in Enclosure B. llll a. Were common mode failures considered due to such effects as ^T lack of physical separation, lack of fuel etc. to all ?.' = l diesels, miscalibration of all similar or redundant instrumants, ssd fire, or earthquake? If so, describe how this was taken into

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• Question 1

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t t b. What were the criteria used to determine what failures would ~ be caused by the LOCA (pipe whip, floeding, etc.) and hence should be assumed to occur in addition to the assumed worst .== =;... single failure? In addition to the short term active mechanical and passive C* .===, and active electrical single failures that were censidered, i identify any passive mechanical failures or passive and active electrical failures that could degrade long term core cool.ing

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""= capability, whether or not those failures were included or required to be included in the FEEA. Further specific l

• information regarding long term containment cooling is requested 57=m.

in Questionll below. ~ .d. Include in the FMEA any effects due to non-operation of all valves which become flooded as the result of a LOCA. ' '.g

e. -- Include in the FMEA resul.ts of assumipg inadvertent operation

-== (opening or closing) of any motor or air operated valve. or I valves possible a,s a result of single operator error. or a cassive ~ l or. active, mechanical or. electrical failure.. Those portions of the FMEA which assume credit for operation 0 f. of the Fire and Well Water Systems to mitigate the consequences of the accident must include the following for both short and. long term core cooling: consideration of the effects (on availability of all .i" =- (1) necessary water that must be supplied by the system) of ~ inadvertent opening of any valve or valves in the system, including all fire spray systems, deluge valves, fire hydrants, etc. (2) consideration of the effects due to providing water'for fire-fighting on availability of all necessary water that must be' supplied by the system for long term core cooling ~or ECCS equipment operation. (3) consideration of passive failure of any pipe or valve = in the system during long term cooling. 9-How do you differentiate between "long term" and "short term" periods following a LOCA? What differences did.you apply in your FMEA for these two time periods for availability of offsite power, type of passive or active failures assumed, and credit for manual actions? E[= e 1

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4. 'In light"o'f'recent data that ss become available to you through 92 1

the General Electric Company regarding effects on spray distribution

==". =+ ] due'to steam environment, etc., and considering the minimum spray flow present in the APED-4927 and APED-4928 tests, justify your

1. 7EE assumed spray cooling coefficients.

^::::.::: 5. Your response to question 2 of our request dated January 26, 1976 =:::.7 d;!, indicated that the ECCS code package used was identical to previous ~ i; nonjet-pump ECCS packages. liowever, those codes were not approved F =s= n t:: for a dual-cycle BWR. We understand that the intermediate loop for your facility is considered in the SAFE code by applying time Ea l;j dependent multipliers to the feedwater enthalpy. Explain how these .3 multipliers are derived and justify modeling the intermediate locp

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in thiis manner. The responses to question 2e of the 1/26/76 questions- <=5:- is not considered a satisfactory description of this calculation. g q 6. What is the minimum time following a LOCA that. requires credit to-be ~~ .; {. taken for manual action?

==. What containment pressure is assumed (or how is it calculated) for = 7* ECCS-LOCA core cooling calculations? ..f.:.. [.. 8. What are the effects of operation of the Emergency Condenser - l= system following various size and location pipe breaks? g. Identify all interfaces between systems subject to full reactor ~

i operating pressure and systems' having a lower design pressure that do not have at least 2 independently operated valves rated for full reactor design pressure.

10. For breaks df su'ch a size and location that it is necessary or I desirable to increase recirculation flow above that which can .+.2 flow out the break, how is water removed from the core? Provide P&ID's of all equipment needed to accomplish this, and include = l any credible failures of this equipment in the FMEA.(Q3) l' ....e The following questions are in reference to your October 17, 1975 report, "Dresden Unit 1, ECCS Design Report". VR 1 ' 11. Provide details of the equipment used to cool the containment. ~ For example, pg. 6.3-26 indicates that eacg heat exhanger-can - remove 15 x 10 BTU /hr, a total of 30 x 10 BTU /hr. The decay heat does not approach this value for about 3 hours - what happens at times earlier than 3 hours? Are the s stems that ej: =a supply the cooling water for containment cooling well water, '== m. fire water, etc.) single failure proof for passive and active =ii=k failures of all types, and are they seismic category 17 i

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h: .-r.- A w 55555b[kE [n;, 7..~.1..... - =5 = .X::: 12. What.is meant by the'"special mode" HPCI to be employed following' =~" " a core spray line break?' (ref. Table 2. August 1975 ECCS Analysis

• 4 plant.with HPCI).

~' ~ 13. Descrilie the sho[t and 1ong-ten sequence of events fo110wi5fa HPCI.line/feedwater line break at the point where the HPCI system inject.- into the feedwater line, with and without offsite power. ,._Q Be sure to include the sequence assuming a core spray pump-diesel. h.. 7 failure: can enough core spray flow be provided from the other H diesel and core spray pump (s) or from the 100 gpm pu..p that runs : g...; ' 4 in== off of diesel power?,

14. a. 'Pg. G.3-8 indicates both PI pumps are needed to accomplish [

~ [ ~~.. long term cooling. With loss of offsite power and failure 2.7 of either diesel generator 1A or 1B, how is long term cooling gh; accomplished? (Table 8.3-2 indicates that only one PI pump E==- can be driven from the remaining diesel). Eiriinie-i. .b. Where does E-4 on Figure 6.3-5 go? !{;.( [ (loop B) go? (Fig. 6.3-1)

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Where does E 8 (loop A) and the equivalent, unmarked pipe c. E= f-E De' scribe' the shaft term and long term sequence of events follev:ir.; I 15. i a core spray line break, both assuming offsite power is and is r.ct R available. Be sure to include in the description.the followir.g ]. information: What supplies long term cooling water to the core, HPCI or a. emergency feedwater pudps? Take into account the 100 psi cutoff on runout of the HPCI pumps. i b. What is the runout pressure and flow for one_ HPCI pump, 4 7= assuming failure of the other ond i 4 Can any of the feedwater pumps be run from onsite-generated .c. ~ (diesel) power?

==a d. What pumps are available that can inject water into the core

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n = l using only onsite power when core pressure is less than 100 psi and the core spray line is broken? [.3... ~ For th'e co're spray line break, cooling with loss of offsite power ^ c. apparently must be supplied by a pump having less than 100 gpm _.7

== - capaci ty. After about 20 minutes, complete vaporization of 100 gpm

==- is adequate to rencve decay heat. How is the steam condensed by the containEent heat Fehosi system before 3 hours '(thd 2 heat a exchangers do not have enough total capacity to remove all decay i== heat) an.d after 3 hours (here the concern is not with total heat Y= removal capacity, but with efficiency of condensing the steam)7 l i r..: g.: i

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tru .er.: i .1 f. For the situation described in 15.e., what happens between' ~ ...] the time the reactor depressurizes to 100 psig (HPCI pump cut off) and 20 minutes, at which time 100 gpm may be

== sufficient to cool the core?.

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i iq~._ 3 ENCLOSURE B =d~.b. E:.rz.4 COMMONWEAL'Di EDISON COMPANY [ElEi?D DRESDEN UNIT NO 1 . T::.T.': DOCKET NO. S0-10 . REVIEW OF ECCS REQUES.T FOR ADDITIONAL INFORMATION. ~ ~

• ";;gg The Acceptance Criteria for E=ergency Core Cooling Syste=s for Light

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==- Water Nuclear Power Reactors,10 CFR Part 50.46, requires that an analysis,of .gg;.

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possible failure modes of ECC',; equipment and of trheir effects on ECOS par-1;_. v:. formance be performed. This analysis should deconstrate that your ECCS and E.;iiiiii ~ supporting subsyste=s ncet the single failure criterion. He requira that doc-i - ymentation of this analysis be provided in sufficient detail to enable the staff T. _ to (1) verify that the ' analysis demonstrates that the ECCS andi supporting [{ subsystems meet.the single failure criterion as defined in IEEE Std 279-1971, b= y ;;;;= and (2) determine the acceptability and verify the implementation of any j . proposed design codification required as a result of your analysis. Therefore we require that the follouing information be submitted to support the single

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failure analysis of the ECCS and supporting subsystccs:

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., h=.t ~ l'. Describe the design of the ECCS actuation system. Identify any non-IW ~ , confornance of this design with the single failure requirements of f..,.,. E IEEE Std 279-1971. Describe any changes proposed for necting these h F._.. requirc=ents. z.; y=._ 2. Describe the design of the onsite emergency power systen, a-c and d-c. 5:E w. Identify any non-conformance of this desigr. uith the single failure requirements of IEEE Std 279-1971. Describe any changes proposed for nceting thcsc requirements. w

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4 'lE 3. Identify all the electrical equipment required for the ECCS and supportin:E fil:5h =-i ~ r.==. l subsystems to enable performance of the ECCS safety function. De- - =-i ,:=- =4 fine the qualification status" (ability to withstand.the design basis [l ;l d ' seismic and c,nvironmental conditions) of this equipment, and the

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6-E :- basis for such qualification, to provide reasonabic assurance that the L= - T'::.:- __ equipment will be capable of parforming its ' safety function. Dascribe + any proposed dasign codifications, analyses, or test progra:s for.

== .==.:=. !-M ceeting the environ antal and seismic qualification require ents.

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4. Identify all electrical equip =ent, both ' afety and non-safety,.that. .[~ s ~ may become sub=arged as a result of a LOCA. For all such equipra:c

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that is not qualified for service in such an environment, provide an 1 y..... analysis to determine the following: (1) the safety. significance of .. p== ' is the failure of the equip = cat (e.g., spurious operation, loss of function,

.g loss of accident / post-accident monitoring, etc.) as a result of

{= g flooding, (2) t.he effects on Class IE electrical power sources serving ,:.g ....: E this equipment as a result of such f:.ilures, and (3) the proposed 7:5:3 nm~ design changes i esulting from your analysis. Your response to item (2) , 7=::;:. should specifically address breaker and f.use coordination and the ,jmj;iF' I i.. :::::.. isolation capabilitics of this aspect of your design. "~5- ~ . =2:::. l 5.' Identify any single electrically operated fluid ' ysten component, .!.t.. ~ s

==#;;.; i including nanually-controlled cicetrically-operated valves, whose [.[:$2. . failure could result.in loss of capability of the ECCS to perfora its

====8 safety function. Failure in both the " fail to function" sense and in 7 1 p.. r1 i: 7 ? I [

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the " undesirable function" sense should be considered, and this should g.. apply even though the component may not be required to function in a [ ,given safety operational sequence. i;:: ......m 6. With regard to the equip =ent identified in iten (5), provide a detailed r.....:.; c: description of any proposed design changes deemed necessary by your y ;. ;;; e f p e 7 analysis for meeting the single failure criterion. Your response ~ should specifically address but should not be limited to changes made . to meet the singic failure criterion by conformance to Branch' Technical Z.- ~ E Posit. ion EICSB 18, " Application of the Single Failure Criterion to' ~ , Manually-Centrolled Electrically-Operated Valves.", of Appendix 74 of-h [E the Regulatory Standard Revicu Plan. This position establish 2s the - acceptability of discondecting power to.the electrical co=per. ends' of a b f fluid systen as one = cans of meeting the single failure criteri:n. [.T t .7. Identify any electrical interlocks between redundant portions of the ECCS and supporting subsystens. Define the ccusequence of failure of any interlock on the capability of the' ECCS to perform its. safety N function. Describe any proposed design nodifications resulting from t c: this revicu. p 8. Provide the electrical and physical separation criteria for your design . of redundant s$fety equipment and functions. Include the features in your design that minicize the vulnerability,of the ECCS and supporting I cubsystccs to coc=on failure modes. ~ L':.. .h 6 Ei.

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. 9. Provide the following drawings for the ECCS anel supporting subsystems: 2=:.s=. ~ f:f: b

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• Piping and Instrument Diagrams (PLID).

b. Electrical Controi Schc=atic Diagrams. ~ = ~ ~ ~ =. c. One Line Diagiam of the Onsite AC Power Distribution Systim. ad th== d. One Line Diagram of the DC Power' Distribution System. L e. One Line Diagram of the Vital Instrument Pouer Distribution. System.' l

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