ML20010J471

Summary of ACRS Ad Hoc Subcommittee on Decay Heat Removal Sys 810706 Meeting in Washington,Dc Re Task A-45, Shutdown Decay Heat Sys Requirements

ML20010J471
Person / Time
Issue date:	07/27/1981
From:	Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
Shared Package
ML20010J472	List: ML20010J471 ML20010J475
References
REF-GTECI-A-45, REF-GTECI-DC, TASK-A-45, TASK-OR ACRS-1875, NUDOCS 8110050130
Download: ML20010J471 (12)

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7/2?/81

/?CRs - /87f MINUTES OF THE JULY 6, 1981

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AD HOC SUBCOMMITTEE MEETING ON DECAY HEAT REtiOVAL SYSTEMS l

WASHINGTON, DC The ACRS Ad Hoc Subcommittee on Decay Heat Removal,Sys'tems met on July 6, 1981 at 1717 H Street, N.W., Washington, DC.

T're purpose bf this meeting was to discuss the Draft Task Action Plan, Task No. A-45, "Shutdowa Decay Heat System Requirements." A copy of the notice of this meeting is in-cluded as Attachment A.

A list of attendees is included as Attachment B.

A schedule for this meeting is included as Attachment C.

The handouts for N

this meeting are listed as Attachment D.

.The neeting was begun at11:00 p.m.

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with a short executive session open to the public in which Mr. Ward,' the Subcommittee Chairman, summarized the objectives for the day's meeting. The meeting was adjourned at 3:10 p.m.

The meeting was conocted entirely in

's, open session. The Subcommittee heard presentations from the NRC Staff.

There were no written or oral statements from the public.

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DISCUSSION OF DRAFT TASK ACTION PLAN:

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,r Mr. Marchese, the NRC's Task Manager for A-45, provided an updated s'tatus

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1 of the task. Key points in this update included-a.

NRC line branches are actively reviewing the draft Task Action Pla9 b.

The final plan is expected to be approved by HRC management oy August 7, 1931.

The current expectation is th'at the. sche 3 ale will slip past this date but that the final plan will' be ovail-able in late August.

NRR manpower and technical ~ assistance funding should be committed c.

by August 7th.

d.

A schedule for acquisition of other technical assistance has been developed.

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The target completion date is still early 1984.

The completion date may slip if resources are not approved.

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.t-q ' _N pt Mr. Marchese stated 4.hht the Staff wanted to complete Task A-45 before 4

. issuing a revision to regulatory guide 1.139 that would require plants to u

M; a e.have the ability to achieve cold shutdown using only safety-grade equipment.

.n Mr. Marchese identified the interrelationshio of sub-tasks in Task A-45.

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Basically, int ceptance criteria will bs developed for existing and future (including those under construction), plants.

Then the adequacy of the de' 6y heat removal systeas will be assessed against these interim cri-c N

te ri a. - A new sub-task was identified which assesses,the adequacy of SDHRS

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in existing plants on. a deterministic basis. Cost effectiveness evaluations s

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and cost comparisons.'can then be made in light of risk reduction.

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' Several Subcommittee members ' identified -the need for the Staff to assess the

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adequacy of decay heat removal systems 'in BWRs as well as PWRs. Mr. Marchese e

S'nd Mr. Berry (Sandia) indicated that acceptanh criteria and risk targets 4

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y -would be developed for both BWRs and PWRs.

San'dia'is looking at BWR SDHRS t

frcm a probabilistic standpoint by varying there ' reliability and seeing if that

,sg 3 [.e511,ly means apything in tenns of overall risk to the plant.

Sandia is assess-f

'ing three alternative DHR concepts for BWRs. Other alternatives such as reflux condensers will be evaluated.

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MINUTES DECAY HEAT REMOVAL

Mr. Epler stated that the operator actions required to activate decay heat g;f Y

rem.sval systams should be minimized. Mr. Marchese agreed that this should be an important aspe:t in assessing dedicated SDHRS.

He added that the Staff was assessing various dedicated systems and had not concluded that a specific dedicated system is necessary. Mr. Taylor (NRC Jaaff) thought that the systems should be automatically initiated with well controlled manual override features.

Mr. Epler identified the need for dedicated systems to be designed so that a failure'of vital equipment et services within the system does not cause the need for those servic'es or equipment. He pointed out that a dedicated decay heat removal system must have no capability whatever of causing plant shutdown thereby causing itself to be needed. Mr. Marchese acknowledged this as a valid requirement of a dedicat2d SDHRS.

Mr. Marchese stated that system improvements and/or installation of a dedicated SDHRS might be requ' red even if there was not much reduction in risk based on exi; ting PRA.

Mr. Davis pointed out that plants decay heat removal procedures need to be reviewed to ensure that they are effective and optimum. Mr. R. Lobel (NRC Staff) stated that DHR procedure; revicwed under the SEP may not fiave included modifications resulting from the TMI experience.

Mr. Epler mentioned that the public's perception of risk might be an important consideration in determining what constitutes an acceptable

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MINUTES DECAY HEAT REMOVAL '

risk. He proposed using enhanced public confidence as a factor in the cost-benefit analysis for requiring system upgrades. Mr. Davis and the Staff discussed this and the attendent difficulties in quantifying the bene fi t.

Mr. Ward questioned Mr. Marchese on the NRC's reasons for not yet requiring an independent and dedicated SDHRS.

He noted that traditionally the scram function was provided with an independent and dedicated system. He then pointed out that safe management of a plant in an emergency or abnonnal situation seems involved a two-headed attack; one is to scram and the other is to remove decay heat after you have scrammed. Mr. Marchese stated that the reason why an independent and dedicated DHR system is not presently required will be clarified as the task progresses.

McGuire and Otonee standby shutdown facilities were toured by Mr. Marchese and discussed at the meeting.

These facilities represent the closest approximatior, to dedicated shutdown cooling systems in existence at com-mer cial U.S. power plants. They are designed to get the plants to a hot shutdown condition and will be manually initiated. The Ocohee system serves all three units and is housed in a separate Seismic Category 1 building. The facility houses a 31/2 MW diesel generator, fuel, and equipment necessary to makeup to both the primary and secondary sides of each unit simultaneously. The Oconee system estimated cost is approximately 534 millior.. The McGuire system is not safety grade, serves two units, and cost apg;rcximately 53 million. The McGuire system primarily prsvides an alternate power supply to existing plant pumps.

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MINUTES DECAY HEAT REMOVAL

• Mr. Ward raised the question of the validity of sorting all plants into the I

six Reactor Safety Study Methodology Application Program (RSSMAP) groups for the purpose of analyzing SDHRS.

Mr. Taylor agreed that such a group-ing r.ay not fit the decay heat removal variations. How-ter, it was generally agreed that similar plants should be grouped for analysis purposes DISCUSSION OF INTERIM ACCEPTANCE CRITERIA:

Mr. Rowsome (NRC/RES) made a presentation on the Interim Quantative Action Criteria he nelped develop with Mr. R. Bernero. These criteria, their bases, and application to Task A-45 were discussed. The probabilistic criterion (one in or.e-thousand chance per unit that the problem gets you between the time you discover it and the time you shutdown or implement the shot t term fix) was recommended for use in making a decision on the urgcncy with which a detected safety vulnerability should be dealt with in a plant. The criterion dealt merely with the discovery of a vulnerability for which a rough estimate of the probability of core melt could be generated. The criterion was to be used in making a decision on whether a plant should be shutdown or allowed to operate for a specified period of time. Thus, the Interim Quantitative Action. Criteria do not represent ideal statistical analysis of acceptable risk. Mr. Marchese stated that of the three sets of quantitative action or probabilistic goals r2ferenced in the Task Action Plan, the ACRS proposal is the most comprehensive. He stated that it prnbably would be the bas'is or the sta.* ting point for the Task Action Plan criteria.

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r-M1WJTES DECAY HEAT REMOVAL.

Mr. Rowsome identified a potential duplication of effort by NRR and RES. He believes that the research program that deals with degraded core cooling rulemaking incorporates virtually everything that is in Task A-45.

Mr.

Marchese did not believe this to be the case. They agreed to determine if overlap existed and to consolidate effort where appropriate.

CONCLUDING DISCUSSION AND SUBCOMMITTEE COMMENTS:

1.

The assessment of SDHRS should identify the extent to which operator cction (system automation) is required.

2.

Dedicated ' OHRS.chould be evaluated based on their independence (SDHRS l

failures. should not cause the need for the SDHRS function).

3.

A deterministic assessmemt of the adequacy of SDHRS ir existing plants should be conducted in paral,lel with the probabalistic assessment froin the beginning.

4.

System upgrades should be required if cost effective benefits can be achieved (e.g. system reliabilities can be improved significantly even if the risk is not reduced significantly).

5.

The Task Action Plan should incorporate a systematic evaluation of SDHRS procedures at existing plants.

6.

The Rowsome/Bernero Interim Quantitative Action Criteria may not be particularly applicable to Task A-45.

However, the criteria may help establish the allowable time for implementing corrective action on plants that have inadequate SDHRS.

MINUTES DECAY HEAT REMOVAL 7-7.

NRR and RES should coordinate the efforts of Task A-45 with those of the degraded core cooling rulemaking research programs.

8.

Similar plants should be grouped together for analysis under Task A-45.

9.

The NRC Staff presentation on Task A-45 should not be given to the full ACRS in July.

Task A-45 should be reported at the July full Committee meeting by the Subcommittee chairman and any comments be added to those of the Suocommittee. That Mr. Marchese should present the final Task action plan to the-full ACRS in August.

4 The meeting was adjourned at 3:10 p.m.

NOTE: For additienal details, a complete transcript of the meeting is avail-able in the NRC Public Document Room,1717 H St., NW, Washington, DC 20555 or from Alderson Reporters, 300 7th St., SW, Washington, DC (202) 554-2345.

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Federal hgist:r / V:1. 46. No.117 / Thursday June 18. 1981 / Notices 31951 4

r RA wti.prende the Board with a wpy. FRA the Designated Feders! Employee as far 6

f reemphasize per.visione and intent of 14 CR 1213stac}(1)(n) and to include unsmb:guous will soon issue a proposed nJe for rensing in adsante as practiable so that the State Particapation Regulations (40 C R appropriate arrangements can be made g

proced ra! guidance (A-81-19) FAA concurs

.u en pa*1 with A-et-20. whenever a CPW5 Part 212) (Ref 45 f1t 63357. Dec.18,1940 )

to aUow the necessary h during 6e R-A%21.fmm the Fedem/Rollrood alarm occurs. the fhghtcrews' respcnse Administration (May 27/-The substanhal meeting for such statements.

shodd be rsaluated and debnefed for cost of either replacing maintenance-of.way He entire meeting will be open to procedural adequny and this trommg cars which do not mmply with Freight Car pubbc attendance.

function wt!! be errI;Mied an the abose no'ed bulletm FAA does not rivocate Safet) Standards or restnctmg their De agenda for subject meeting shaU h'

afterma riustes alt carrier a%1ator mosement to work trains cannot be pstified g as gogjows.

curncute in actord witn A-81-20 (Ref 46 FR Railroads impose restnctions on use of these cars to assure safe operation. Maintenance-Monday, July 8,1981 16366 Mar 12. t wil )

of-wa> cats are lmuted to slow speeds and LWp.m. until the conclusion of business A-as-21 and-22(May 26)-FAA wnll local tra:ns nere is not intent to allow espedite.esuance of gn airwntthiness maintenacbof.way cars to be used as During the initial portion of the

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directive (AD) to require rnore frequent revenue cars which operate at timetable meeting. the Subcommittee, along with t,nspectiona and replacement whenever any apeeds in free interchange service. (Ref. 45 FR any ofits consultants who may be crack or stress craze is found (A-41-21i 73832. hhv. 8, *M i Supplerner.te 9 infonnation cor.cerntng A-do-n % the Association of American present, will exchange preliminary barards asic ested with cracked or crared

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cast acr>he wdows will be addressed m e Railroods !9ay 24-Pirst aid trainmg must views regardmg matters to be 9

follow-on ADIA-41-22) (R+f 46 FR 16r.3.

not be mandated. With asallabihty of considered durmg the balance of the doctors hospitals and eme ency repsonse meeting The Subcommittee will then Mar 26.19e1 )

EP hear presentations by and hold

• OtherRecommendation Responses-

[,7)e*h woulb N'e'm' h discussions wi'h representatives of the u

N-49-st from the Nat onc/Hghncy lunited. a compulsor) program covenng a!!

NRC Staff, their consultants and other Tm/fic Safet) Administration (Arc 3 Je/-A employees would not be costbene*icial (Ref interested person regardmg this review.

19'a contract with the Americaa Assocation 4e FR ral l6a. 2.1901 )

of Motor Vehicle Administrators includ.d a Note.-Single coptee of Board reports are Further information regardmg topics requirement to duelop a problem s'atement as silable without chartre es long as limited to be discussed. whether the meet 2ng on multiple licensmg In late 19'9 some 3 500 suppbes last. Copies of *ecommendation has been cancelled or rescheduled, the interstate truck dnsers were rando n?y letters. responses and related correspondence Chairman's ruling on requests for the selected for a records check m all States and are also free of charge A!! requests must te opportunity to present oral st.atements Canadian Provinces. a report will be in writmg identihed b* recornmendation or and the time allotted therefor can be avolable in jial) 1981 A study of multiple report n.anber Address requests to. Pubhc obtemed by a prepaid telephone call to licensing among the general dnvmg

• Inquines Section. National Transportation the cognizant Designated Federal population is undemay, sched.ifed for Safety Board Washington. D C. 20%4 Employee. Dr. Racherd Savio (telephone completion in Octcher Senous Multiple copies of Board reports may b, I

trnplementation difficulties (sist smee State purchased from the National Technical 202/8W3267) betwegn 8.15 a.m. and officials are bound b> their own State law: if Information Service U S. Department of SM p.m.. EST.

la not now possible for them to corform full)

Commerce. Spnngfield. VA 22161.

to the one heartselone record concept To (49 U.S C.19Cn(e)(2).19031 John C. Hoyla.

g assist States in improving thor laws MfT$A Margaret 1. Maher.

Advisory Committee Afanagement Odficer.

has developed a Traffic law s Commentary.

I "Dnser lacensing Laws Rated " The Counci)

Tedero/RegisterLiasion Officer of State vosemments' study of State June 12.1981 en,,

g participation in the Driser License Compact pli ca. m-isrs Pwe e-o at ses..el is pendmg pubhcation. and a third amic, coce as,o-a.as the United States " has been dismbuted to all

--- Advisory Committee on Reactor pubbcation. " Class:fied Dnver I; censing m licensing junedictions. (Ref 45 FR 163c3. Mar.

NUCt. EAR REGULATORY Fuel; Meetin'g 13.19801 COMMISSION H-m-28. f.w the Secretary of

.The ACRS Subcommittee on Reactor e:Eng$nYprop tj Advisory Committee on Reactor Fuel will hold a meeting on July 7.1981 Safeguards, Subcc.'nmittee or; Decay in Roem 1046 at 1717 H Street. NW.,

e reg ns e effort is being rr.ade to ensure that the Heat Removal System; Meeting Washington. DC to discuss NRC Fuel operatias administrations classify and Behavior Research Programs. Notice of asamte regulations accurate!> and full >

The ACR5 Subcommittee on Decay (Ref 45 FR 5?6(6. Aug 28.1980 )

Heat Removal Systems will hold a this meeting was published June 19.

Af-74-J and Af-?d-9. from rAc US Coast meeting on July 6.1981 in Room 1046.

In accordance with the procedures 1717 H Street. NW Washington. DC to outlined in the Federal Register on re5at ng fduca nel d ra r rn ane to review Task A-45. " Shutdown Deca, October 7.1980 (45 FR 66535). oral or better mform towboat operators is not under Heat Removal Requirements." Notice of, written statements may l presented by USCC's pu view Training schools and tests was published June 19 members of the pubhc. recordings will bots were prended as a guide fe evaluatmg this meetinyance with the procedures be permitteli only during those portions In accor an afternative resonse to the recommendet.ons The Secretar) approved outhned in the Federal Register on of the meeting when a transcript is being (raderal Regialer. Mar.16 tral) the charter October 7.1980. (45 FR 66535), oral or kept, and questions may be asked only for thelow mg Safety Advuory Committee, written stalements may be presented by by members of the Subcommittee,its to which M-76-3 and -e ar.d spporting data members of the pubhc recordings will consultants. and Staff. Persons desinng will be forwarded for apprornate action.

be pemitted uly durirg those portions to make oral statements should notify of the uteeting when a transcript is being the Designated Federal Err.ployee as far

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kept, and questions may be asked only in advance as practicable so that Railroad Adr,snistration f/une 31-The by mernbers of the Subcommitee,its appropriate arrangements ca's be madr Spiems Safe.) Plan is under final review.

consultants, and Staff. Persons desiring to allow the necessary time during the upon clearance by the Office of Management to make oral statements should notify meeting for such statements.

and Budgat for submission to the Coogress.

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r-PROPOSED AGENDA FOR JULY 6,1981 MEETING OF THE DECAY HEAT SYSTEMS REMOVAL SUBCOMMITTEE 1.

Executive Session 1:00 - 1:15 pm 2.

Discussion of 9raf t Task Action Plan -

1:15 - 3:15 pm Task A-45 " Shutdown Decay Heat Remova'.

Requirements" (a) Briefing on Draft Task Action Plan 30 min (NRR)

(b) General Discussion and Subcommittee 90 min Comments Break 15 min 3.

Discussion of Interim Acceptance Criteria, 3:30 - 4:30 pm Basis, and Application to Task A-45 (Ref:

Juif 29, 1980, NRC letter from R. Bernero to R. Mattson, entitled " Interim Quantita-tive Action Criteria")

4.

Concluding Discussion and Subcommittee 30 min 4:30 - 5:00 pm Comments a

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l ATTM% M E NT t

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e LIST DOCUMENTS PROVIDED FOR THE MEETING l

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Tentative Meeting Schedule 2.

Slides used by A. Marchese, "NRC Staff Status Report on Unresolved Safety Issue (US1) - Task A-45, Shutdown Decay Heat Removal (SDHR)

Requi rements."

(5 slides) e 9

ATTACHMENT D

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