ML20206A356

Summary of ACRS Subcommittee on B&W Reactor Plants 880503-04 Meetings in Washington,Dc to Review Reassessment Program

ML20206A356
Person / Time
Issue date:	07/14/1988
From:	Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
References
ACRS-2575, NUDOCS 8811150090
Download: ML20206A356 (22)

Text

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002-EMS CERT!FIED COPY

.l DATE ISSUED: July 14,1988 i

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SUPPM.Y/Mih0TES OF THE ACRS SUBCOMMITTEE 11EETING ON B&W PEACTOR PLAhTS i

MAY 3-4, 1988 f

WASHINGTON, D.C.

l FURPOSE A meeting was held by the ACRS Subcomittee en Babcock & Wilcox Peactor

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Plants on hay 3-4, 1988..The purpose of the meetirg was to review the ElW Owners Grcup Plant fetssessrent Progren. Presentations were made by the B&K twrers Group (EkOG) and the hPC Staff. Notice of this meeting I

wtr, rublishec on April CC, 1968, in the Federal register. Attachment A is a schedule of presentations. The meeting was entirely open to the j

public.

Pichard Major was the cegnizant Staff Engir.eer for this meet-l ing.

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I; ATTENDEES f

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ACRS NRC STAFF l

O ylie, Chairnar.

5. Siegel j-C. Mictelson, Mer.ber A. Smith

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D. Ward, Perber R. Jeres l

H. Lewis, P& ber W. Le Fave

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W. Lerr, Pembcr H. Rubin j

H. Etherington, Consultant J. Calvo i

l P. Davis Censultant G. Hamcr

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G. keed, Consultant A. Cappucci

!. Catton, Cor,sultant R. Foyle R. Major, Atk$ Staff W. Feinke R. Kende11

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BWOG f

i G li11ran OTHERS l

N. Rutherford C. Lewe, NUS l

C. Fengge A. Wycte, Search Licensing /Fechtel S. Pese C. Berge, American Nuclear Insurers 4

L. Stalter J. Rogan, NPR Associates l

R. Ganthner N. Cole, MPR Asseciates l

J. Taylor

1. Coffenberry, Heritage Reporting

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A. Mercado B. Strict 1and EGI J. McColligar F. Youngblood, BNL W. Kessinger P. Amico, ARTECH L. Haack B. de Grazia. Furditt Bunles J. MacEvoy, Coluen One, Inc.

E. Kane H. Moeller, Batte11t, FhL

( m c e. R. McGeey %{}

J. De Bor, SA!

i P. Liddle

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B&W Reacter Plants Feeting Minutes May 3-4, 1988 MEETING HIGHLIGHTS. AGREEMENTS AND REQUESTS Mr. Byron Siegel, Head hRC Project Manager, BWOG Plant Reassessrree' Effort, presented an overview, of this effort. He explained the his6ory behird this effert, b*ginrict with concerns raised by tLe EDO, following several ogretienal transients that raised the subject of plant sensi-l tivity in early 1956.

These concerns lead to an effort to reassess the overail safety of PLW plants tc detenire if present requirements are afgrcreiate fer the long-tert and lead to a level of safety comparable to other PWR8.

In february 19F6. the SWOC comitted to take the lead in l

this e*fert.

In July IU 7, the BF0G produced Fevision 5 to BAW-1919 the Safety ard Terforear>cc Irproveront Program (SPIP), which contains their recerrendatier.s tc improve the B&W plants.

Tte Staff hes had centinctus interactien with the EWOG on tht scope of SFIP projects.

They reviewed and evaluated SPIP results.

The Staff l

aise performec irdependert >:crk in certain areas including:

risk evaluction, hurin factors, lit 1ted thorrr.1 hydraulic analysis, erd a limited crerating etperience review.

The Staff's !EF ar.d SSER certein no new Stoff positters. These docu-tents ccrtain rc Staff requirerents, eniy reco rendations offered for j

censideration.

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I F.:. F.ichehtr cuestioned whether these B&W plants were any rcre suscep-tible to external twents such as fires, flooding, and pipe breaks outsice of contairrent. % e Staff resper.ded by noting that this review was limitec to design bs34s and systern reviews ard past operational problens. Other regulatory programs deal with the external events of concern, ht this prograr did not.

i Mr. Neil Rutherford, Chairman of the BK0G Steerirs Comittee, introduced l

the BWOG and stated that the objective of the reeting was to provide Sufficient inforestion to allow the ACRS to corclude that the PWOG l

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B&W Reactor Plaitts Meetir.g Minutes May 3-4, 1988 i

Safety and Ferformance Irprovement Progran adequately addressed the complex trar.sients tr.d trip-related safety concerns on B&W plants.

fir. Peed coverted that I,( tFought thernal hydraulic phenenena deserved rcre attenticn in this prcgram.

He felt natural circulation cooling of the core deserved addcd errphasis.

Mr. Rutherferd roted that the prograr was directed at complex transients ard desigr cuestions which resulted from them, hatural circulation i

tests went tryend the scc;e of the $r]p.

I Pr. Dick 56illman. Ev0G presented a sumary of the progran and the results.

At the center of this program was the issue th'; vplex trarsients wtre too fregocnt and their safety significant

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Complex trarsients were defined in terrs of reasurable parane-ters. Their tesiden f rcr. preferred ranges was used as an irdication of conplexity.

Quantification cf the issue permitted pinpointing the y

functiert.1 ar.d syster areas of ir.terest.

Tte EWOG believed this to te a substan'.ial progran.

The owners have irsested ir tre neighberFccc of $10 n.1111on and spent over one hundred fra n-yea r s.

Mr. Skillrtr explaired the overall ebjective of the prcgram was to irfreve safety.

The BWOG 58 ad to reduce the number of trips and complex transients cr, F8W Owners Group plants, and ensure ac:eptable plant respense during those trips and transients which do eccur. The pregram has twc najor goals:

(1) by the end of 1990, the average per plant trip frequency will be less than two per year, and (2) by the end l

of 1990, the rumber of coeplex transierts will be reduced to 0.1 per plant, per year, based on a roving three year average.

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B&W Reacter Plants Meeting Minutes May 3-4, 1988 Dr. Catton P.cctioned that some of the complex transients under consid-eration can not be reproduced in the MIST test facility. This facility was designed to study the thermal hydraulic' behavior of B&W plan, If actual transients can not be modeled Dr. Catton questiened the.arrent understanding of these transients.

Mr. Skillmer. noted there v:ere three phases to the SPIP program.

The first two, now complete, were informatien gathering and integration.

l Ongeing is the implementaticr phase.

In the irfcrmatior, gathering phase, operating experience was reviewed for the period 1980 through 1985. The trips and ensuing transients for this rcriod were evaluated.

Prcblem areas were sought in b9th the NSSS and the balance-of-plant.

Oparations and traintenance personnel were interviewed. An outside consultent was employed to assess the relative B&W plant sensitivity.

The BK0G also performed a probabilistic risk assessrrent review of previously completed FPAs on B&W plants.

A performance and reliability review of systems ard components was undertaken to identify reconnendations for improvement. These systems included:

ICS/M;1, Main Feedwater, EFW/ Auxiliary Feedwater System,

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secondary plant relief systems, and the instrunent air system.

l Operationt and Maintenance personnel were interviewer' usi.1g an INPO

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developed focused interview process. One of the main objectives of the l

interviewt was to look for transients which may not have resulted in

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reactor trips, but were censidered to be significant. A goal was to find improvements which could reduce the need for post-trip operator ections. This process also tracked down and defined concerns with procedures.

f The BWOG executives established an ineependent advisory broad. This advisory board was to evaluate the program's comprehensiveness and safety

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,BLW Reactor Plants Meeting Minutes May 3-4, 1988 enphasis, and evaluate the ability of the program to achieve its objec-tives. This group was comprised of individuals from outside of the

BWOG, From within the BWOG, a safety ar.d performance recommendation inte-gration grcup (SPRIG) wts established.

This group studied the inte-grated efftet on plant behavior of the various recommendations. They also tried to prioritized the recor2r.endations and select from all the reccreendatinrs those deerred most intnrtant and beneficial to safety and perforrance improvemt The ove"*1 findings and conclusions from the SPIP were listed. These includr.

the risk of core damage is cor. parable to other PWR designs, areas of sensitivity are different than other PWRs. The pressurizer size is adequate, the OTSG inventory is adequate, operator burden is acceptable, the plant is rcre responsive to secondary side changes, and recorcendation implenentation will further irprove safety.

Vr. Skillmtn reviewed several findings and conclusions regarding the cor.plexity of transients. He noted ccrplex trar.Lients are principally the result et mismatched heat balance between the primary and secondary l

systems.

Overheeting events have higher safety significance than other events, but are infrecuent conpared to overcooling events. Overcooling j

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events rey be precursors to overheating transients. Overcooling events i

dominate the nisbehavior of the secondary plant relief and emergency i

fet haar systems. Overcooling events also contributed significantly to che.". ;,oehavior of the ICS/NNI and main feedwater systems.

l Ninety percent of the complex transients are overcooling events.

Overheating events account for about eight percent of the complex f

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transients.

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B&W Reactor Plants Meeting Minutes -

May 3-4, 1988 It was also reported that the majority of trips are caused by balance-of-plant systens, components, er personnel. The dominant trip initiator is currently the rne.in feedwater system followed by the ICS/NNI inputs and plent power electrical rrt.lfunctions.

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Eeg6rding the overall valve of SPIP, Mr. Skillman thought the attention focused er B0P issues was very beneficial. The progran further con-firned the value of a group effort on conven concerns.

In respense to a question fror. Dr. Catton, it was explained that the cperator burden review was not'a cerparison arrong the thre) PWR types, it was a review to assure the owners that their operators could ade-quetely operate E6W plants.

Dr. Catton noted that without a source of feedy:ater, the stee.m generators dryout in a minutes on B&W plants, 20 minuter or, CE plants, and 60 minutes en Westinghouse plants. He be-lieved the need for vapid er. tion to prevent dryout did create greater l

operator burcen.

kr. Skilln tr roted that there are tv:0 areas where the Staff r,rd the Owners Grcup ere in disagreement over the ST.P.

The first is the centent of the ICS/NNI systen review.

The second is the use of human I

fcctors exrcrtise in the SPIP revievt process. There are still open l

araas in the irplementation phase.

Schedules still need to be devel-ope d.

There are also a nunter of engoing activitice including: an emergency operating procedures review, a valve task force report, and a trar31ent assessment program annual report.

Mr. Robert Jones of the NRC Staff presented the NRC Staff's sungnary and concl>sions regarding the SPIP. He explained operating experience fonns the inajor basis for the program.

Emphasis was placed on balance-of-plant systems. The BWOG did not incorporate all the Staff's consnents.

Future transients could result from not addressing Staff concerns, s

B&V Peactor Plants Meeting Minutes May 3-4, 1968 However, the Staff believes SPIP was comprehensive and will improve the safcty (,f B&W plants.

Mr. Michelson again reted external events were not included in the scope of this program. With a limitation such as this, he questioned calling this prcgram an overall safety review.

Mr. Jcr.es listed significant improvements expected from the program.

These included iraproved respense to ICS/hhl failures, improved heat sink reliat>ility and irprovements to the instrument air system. Other impreverrents that the Staff expects are:

reduced reactor trips, reduced challenges to safety systems, reduced operator burden and enhanced operctor perfomer.ce, and reduced risk of pressurized thermal shock.

The Stcif noted that they are still pursuing several significant issues with the BW0G. The Staf f is tracking the implementation of the program recorm er.da tions.

There is some concern recommendations are not being implererted in a tirrely fashier. The Staff believes the BWOG should use 4

human factors professionals to ersure hurran factors concerns are '; den-tified.

The Staff also wanted the BWOG to ensure IE Bulletin 79-27 "Loss of Ncn-Class 1E Instrumentr. tion and Control Power System Bus During Operation," has been appropriately addressed by the rember utilities.

The Staff recorrends verifying implementation of IEB 79-27 as part of the plant specific audits.

Mr. Jones noted that with respect to information gathering, the Staff reviewed specific BWOG reports.

The Staff also did serre independent audits of SPIP activities to assure themselves the Bh0G activities were appropriate.

The Staff concluded the overall thrust of SPIP with its err.phasis on operating experience was responsive to Staff concerns.

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'B&W Reacter Plants iteeting Minutes May 3-4, 1988 The BWCG discussed previous ACRS concerns which were contained in a July 16, 1986, ACRS report. The ACPS report raised thiec issues:

(1) the effectofoperatingorgariizationensystemperformance,(2) safety significar.ce of unique BlW plant characteristics, and (3) attention to decay her.t removal. The BWOG corsiders the role of management very in;pertant, but believes issues relatirg to management are best treated on a plant-specific basis. The safety significance of unique B&W plant characteristics was addressed in the SPIP sensitivity evaluation and risk essessment review.

Atter. tion was paid to decay heat removal in reviews of the F.FW, AFW/ErW, arci fleed and bleed cooling paths. A need for additional cecay heat remeval capability is considered unnecessary.

Regaroing the effect of operating organization, Mr. Ward noted that the thrust of the ACR5 reconrendation centered on the fact that the three Oconee units had ret had any complex transients. They appeared to be a separate pcpulation within the group of B&W plants.

It was asked if these plants had been examined to determine the reason for their suc-cess? For example, dc these units have better operating procedures?

The CF0G had not specifically explored this issue.

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!!r. Stewart Rese, BWOG, discussed the sensitivity study undertaken as a part of the SPIP. The Owr.ers Group enployeed MPR Associates to assess differences in thermal hydraulic behavior arising from differences in j

design. A comparison of a typical B&W unit was made against representa-tive CE and Westinghouse reactors. The purpose of the study was to quantify relative thermal hydraulic differences between designs, i

The sensitivity study's scope included the thermal-hydraulic response of the reactors and steam syster.s during normal plant operation and for anticipated operating occurrences.

Plant thermodynamic responses were also compared fer selected accidents.

Protection and control systems were assessed for design differences sffecting the complexity of l

4 B&W Reactor Plants Meeting Minutes May 3-4, 1988 hardware. Also reviewed was an operator responsibility comparison during normal and off-normal cperations.

The study showea that several aspects of the B&W desigr. which were t

believed to cause "greater ser.sitivity," in fact, did not, These include:

pressurizers on B&W units are as large or larger than, other FWRs, B&W units are less sersitive to steam demand upsets, and B&W units do not impose greatcr burdens on operators following most (normal) reactor trips, a

Stecific corclusions frcm the sensitivity study indicate that relative to other PWRs; B&W units:

• Are not nere sensitive to reactivity upsets;

• Are not more sensitive to reactor coolant flow upsets;

" Are less likely, on avercge, to experience a 'ieak leading to a net loss of ccciant;

• Are so:rewhat lors sensitive to stean derrand upsets such as load i

rejections and turbine trips; a reactor trip on a turbine trip is not required to ensure plant safety;

• Are not more likely to overcool followirg a reactor trip;

• Are r. ore sensitive in their response to m6in feedwater upsets (though the frequency of such upsets is not greater than in other l

PWRs);

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• Are, in some but not all plants, subject to greater cooldown rates from overfeeding of errergency feedwater;

t B&W Reactnr Plants Meeting Minutes May 3-4, 1988

• Are equivalent to many other PWRs in terms of time available to use alte'rnative means of decay heat removal, on a complete loss of all feedwater;

• For most reactor trips, de not impose greater control b-,* dens on plant operators; and

• Impose greater burdens on plant operators in diagnosing and re-spcr. ding to failures of autcmatic control systems; such failures are mere likely to leed to complex transients in B&W units.

There were five major reconmendetions as a result of the sensitivity study.

These recomendations included:

• F.cdifications to IC.C cre essential to substantive reduction in frequency of feedwater upset and to the elimination of the complex transient; Reduce by an order of nagnitude the frequercy with which main feedwater upsets occur; Limit the maximum flow rate delivered by the emergency feedwater system.Sr reduce the likelihood of a persistent demand for high flow; l

Perfort analysis for and obtain licensing approvals to remove the anticipatory reactor trip on turbine trip.

(Thistripincreases the plant's susceptibility to overcooling without markedly increas-ing overall plant safety); and Employ the turbine governor valves to relieve surplus energy following a reactor trip in lieu of employing atmospheric dump valves, turbine bypass valves and main steam safety valves.

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E&W Reactor Plants Meeting Minutes May 3-4, 1988 The last two recomendations were classified as an option by MPR associ-ates.

The results of the sensitivity study were examined by a peer review group. This group included utility, vendors, and NRC (observer) ther-ral-hydraulic aralysts. This group concluded the analysis and results are technicelly sound and appropriate for the study's comparative scope.

The results are not sufficient to draw conclusions on design changes.

Finally, subsequent evaluation of ICS design changes should carefully consider trtal impact on plant respense and operator / transient aspects.

Pr. R. C. Jones, KF.P., presented the NRC Staff's views on the sensitivity evaluation. Among the Staff's findings from the study were:

' Confirmed B&W plants are more sensitive to feedwater upsets;

• EAW plants are not more sensitive to other upsets focluding upsets in steen. flow;

• B&W plants piece greater reliance on EFW, including proper regu-letion of EFW flow;

' Operator buroen is not greater for normal reactor trips, but it is greater follewing failures of ICS/NN!; and

• Once through stean generator (OTSG) design bas certain operational and tube integrity advantages; although the benefits are offset by inherent responsiveness of OTSG and small water inventory.

How-ever, if the systems that interact with the OTSG are properly I

controlled (e.g., ICS/Nh! and EFW) post-trip response will be acceptable, j

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- i B&W Reactor Plents Meeting Minutes P.ay 3-4, 1988 The Staff was in general agreement with the results of the SPIP sensi-tivity study.

Mr. L. Stalter discussed the Bk'0G's evaluation of the ICS/hNI. He noted

.the ragnituc'c of the ICS/t.NI evaluation effort was large.

i Recomendations were c.lassified irto three levels:

(1) Level I con-tains thcse items which will previde immeciate improvt.ments in the operation, availability, and reliability of the ICS/NNI, (2) Level 2 recommerdctions are these which pctentially involve major rnodific6tions to the existino equiprent and require further in-depth evaluation before approval, and (3) Level 3 contains those items which censist of replace-ment of the existing system with a new system based on modern digital technology.

Conclusior.s form the ICS/hNI study indicate vulnerabilities still exist in the ICS/NNI desigr and loss of power may still occur, however, ir.rlementation of Level I recommendations will reduce trips and tran-sients coaplexity and compensate for vulnerabilities.

Follow-on activ-ities are being activcly pursued.

Mr. Stalter discussed c bkOG program on an Advanced Control System.

This systen could poter.tially replace the ICS/NNI. The Advanced control system will tc a plant centrol and tronitoring system. The plant control design will have improved centrol techniques, more operaticral features and increased reliability. The monitoring features will predict and dctect failures and alert operators. The BWOG believes this program is leading the industry in state-of-the-art control technology.

Mr. R. Kendell of the MC Staff presented the results of the Staff's review of the ICS/t.. study. The Staff believes the BWOG review plan for the ICS/NNI evaluation is excellent.

Implementation of the BWOG rece w endations relating te the ICS/NNI should prove successful in

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Bh Reactor Plants Meeting Minutes May 3-4, 1988 achieving a reduction in reactor trip frequency and transient complex-ity. The Staff noted that information provided in BAW-1919 is not sufficient for the Staff to conclude that all ICS/NNI concerns will be resolved as a result of the SPIP.

Regaroing IE Bulletin 79-27 "Loss of Non Pass IF Instrumentation and Control Power System Bus During Opera-tion," the Staff recommends verification of its implementation during plant specific aucits. The Staff concluded that it appears that the BWOG SPIP effort will bc successful in achieving significant improve-roents in ICS/NNI desigrs ano operations.

WEDNESDAY, EAY 4, 1988 Mr. Skillman, BWOG, presented the results of a number of systems re-views.

Included were reviews of the following systems: Main feedwater (MFW), Auxiliary Feedwater/ Emergency Feedwater (AFW/EFW), Secondary Plant Relief System, and the Instrursent Air fystem.

The MFh systen review process focussed on MFW events that occurred during 1984-1985.

Informatior cr; operating procedures and characteris-tics, designs, end maintenance practices were gathered for cach plant.

A one week site visit was conducted to interview operating and mainte-rar:ce personnel, perform system inspections, and review recent transient daic and prob 1cns.

Findings were compiled into 42 recommendetions with generic or plant specific applicability aimed at improving the reliabil-ity of the MFW and condensate systems.

l The Emergency Feedwater review process complied functional design objectives, testing objectives, and a list of maintenance recomenda-tions to improve reliability / availability.

The goal of this review and its subsequent recommendationt was to prevent excessive EFW flow that had resulted in overcooling tvents.

l The Secondary Plant Pressure Control System was reviewed. The transient assessment progran (TAP) data was reviewed to identify problems related 4

r ELW Reactor Plants Meetir.c Minutes May 3-4, 1988 to main steam :afety valves (MSSV) and turbine bypass valves (TBV),

and/or atnospherie derr valves.

The review identified and perfomed a preliminary asses;rtnt of methods of reducing the frequency of MSSV lifts. ": M ds were identified to increase the reliability of both MSSV and TBV.

Post-trip feed and steam flow has been a contributor to complex transients.

Better metheds to control these parameters were sought.

The instrur.cnt air system review compiled air system features and operating data.

Critical air-actuated components were identified.

Plant retpense to cen.plete air icss was evaluated and functional target criteria and recernendations developed. The goal of this effort was to correct air system failures and ensure that the plant will go to a known safe r. tate on less of instrurent air.

Mr. William Le Fave, NRR, preserted a sumary of the Staff's review of the SFlf systems review of ;he aechanical aspects of HFW, AFW/EFW seccrdary plant relief and instrument air. The Staff concurs that proper implerrertation of reconrendaticns will reduce the frequency of HFW/ccrdensate induced reactor trips and severity of transients. He ahn acknowltdged the importance of the balance-of-plant systems.

NFW/ Tut H ne control problems are the major cause of BOP related-trips end plant trips. He noted that Staff reviews in the past focused on the impact on santy-related systems.

Teday's focus is on the frequency of E0P challenges and operator control.

The Staff review of the AFW System tried to verify that racemendations do not conflict with NRC regulations. Many recomendations call for analyses / evaluations by utilities. The Staff will not be able to assess actual benefits until these recontrendations progress further in imple-mentation process.

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Mr. Le Fave explained that the secondary pisnt relief system review censisted of a main steam pressure centrol review to reduce MSSV i

.a, B&W Reactor Plants Meeting Minutes May 3-4, 1988 actuations following reactor or turbine trips. The Staff basically agrees with the approach taken, but recomends the BWOG continue to investigate plant modifications and escalate the analyses if necessary.

The Staff agrees with the conclusion and recomendation of the BWOG instrument air system review.

The Stt.ff believes recomerdations for air system irprovements co not require extensive evaluation or analyses before implerertation.

Mr. Skil' mar of the BbOG briefly described a valve reliability Task Bree ferned by the Owners Group. The Task Force is studying several significant types of valves including rain steam safety valves, motor operated valves and other pet.er operated valves, as wcil as, power operated relief valves, block valves and check valves.

This effort is air.ed at improving valvr cointenance end procedures, and is trying to develop better testir.p techniques.

The Staff is monitoring this effort.

Mr. Ocseph De Bor, SAIC, presented the Staff's human factors evaluation of the B&W plant reassessment program.

The everall assessment of the E'6W findings were:

• The B&W studies resulted in valid human engineering concerns.

Hewever, tsecause human factors professionals were not involved in the reassessment effort, the completeness of the effort in identi-l fyirg human factors concerns is uncertain.

• The proposed corrective actions imply very significant changes in l

the man-machine interface environment in control rooms; but they are general, and not plant specific.

• The proposed corrective actions do not include implementation dates.

B&W Reactor Plants Meeting Minutes May 3-4, 1988 The general recerner.dation resulting from this review was to include human engineering experts as members of teams that will irrplement plant nodifications resulting from the SPIP.

The Owners Group stated that they did consider human factors concerns, although not to the satisfaction.of the Staff.

However, the BWOG believes that their eetions have or will corsider human factors concerns appropriately.

I'r. Skillner. 01scussed the risk assessment review which was performed as part of the SPIP.

This review used the Oconee Level 3 FRA and the-Crystal P.iver Level i HA.

Fault trees were produced, which accounted for the various severe trar.sients that have occurred at the various B&W plants.

/reng the insights obtaired were that Category C transients (complex transients) at these units have minimal core damcge risk.

It was also four.d that feed-and-bleed cooling capability is an important accident mitigator for B&W units.

While the BWCG intends to reduce the frequency of or eliminate altogeth-er the Lt.tegory C ever,ts from a pure PRA perspective, the risk assess-ter.t review indicates that PAW Category C events are receiving more attention than their core damage risk importance indicates is warranted.

Tf,e f:PC Staff had Brookhaver National Laboratory de en independent review of the EWOG risk review. Dr. Youngblood, BLW, described this review and presented the following conclusions:

• As a class, B&W plants cannot presently be said to have a core damage frequency significantly areater than that of other plant types;

• Overcooling events dominate Category C frequency, but are minor contributiens to core damage frequency at all plant types;

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.B&W Reactor Plants Meeting Mint.ter

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• Of those Category C events whi(.h are experienced, undercooling is the event r'ost likely to lead te core damage; and

• Of these Category C events which are experienced, loss of ICS function is considered to be the most signtficant initiating event.

The BWOG explained that tney will use a very femal monitoring system to ensure the recorrendations from SPIP are implenented et the various plants. This system will aise ensure recc rendations are implemented on a, timely basis.

The Staff is tracking the irrplementatier cf the program recomendations.

There is some concern on the part of the StMi cver how rapidly rec-ort endations are being it..plenented.

The Subconriittee recomended this reviu be brought before the full Cormittee during its May 19E8 neeting. The intent was to recomend that ACFS write a report containing its adYice to the Cemission on this j

review. The letter writing was continued into the June 1988 meeting.

lhe meeting wet adjourned at 6:00 p.m.

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NOTE:

Additicnal meeting detai b can be obtained from a transcript of this rneeting available in the NRC Public Document Room, i

1717 H Street, N.W., Washington, D.C., or can be purchased from Heritage Reporting Corporation, 1220 L Street, N.W.,

Suite 600, Washington, n.C. 20005, (202) 628-4888.

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ACRS SUBCOMMITTEE ON B&W REACTOR PLANTS MAY 3-4, 1988 WASHINGTON, D.C.

BWOG PLANT REASSESSMENT PROGRAM Tuesday,f g 3,_1988 8:30 a.m.

'1.

Opening Statement - C. Wylie (15 Min j

a. Purpose, objectives

b. Future ACRS actions

c. Review of schedule 8:45 a.m.

2.

Overview by the NRC Staff (30 Min.)

a. History

b. Organization

c. Involvement of BWOG

d. Future actions i

9:15 a.m.

3.

Sumary and Conclusions (BWOG & Staff)

(1 Hour)

a. Introduction by B&WOG

- how review was conducted

- the scope of the review

b. Sumary of Primary Findings - Recomendations

- broad categories - types of conclusions, recomendations

- assessment of plant safety

c. List of "Open" Areas

- sumary of issues where the NRC Staff has offered substantative alternative 1

suggestions to BWOG proposed course in l

SPIP (e.g. human factors expertise, resolution of previously identified concernsonICS/NNI,etc.)

- methods, schedules for resolving differences BREAK 10:15 a.m.

10:30 a.m.

4.

Disposition of Previous ACRS Concerns of (45 Min.)

of July 16, 1986

a. Effect of operating organizations on system perfomance, rather than 1

concentrating entirely on system design.

l l

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f

b. Significance of fact B&W units are more quickly responsive to load changes and other external challenges than other PWRs.

c. Conclusions regarding the ability to trip the reactor and remove decay heat.

11:15 a.m.

5.

InformationGathering(BWOG/ Staff)

(45 Min.)

- Description

- BWOG Finding

- Staff Evaluation LUNCH 12:00 N00N 1:00 p.m.

6.

Sensitivity Evaluation (BWOG/ Staff)

(1 Hour)

- Descriptien

- BWOG Findings

- Staff Evaluation 2:00 p.m.

7.

Systens Review (BWOG/ Staff)

(2 Hrs.)

a. Integrated Cnntrol System /Non-Nuclear Instrumentation

- system description, requirements

- review areas

- recomendations

- discussion of a system to replace the ICS/NNI

- Staff evaluation

- Status of more detailed Staff ICS/NNI reassessment report b.

Main Feedwater System Review

- Description of review

- BWOG Findings

- Highlights of BWOG Valve Task Force Effort

- Staff Evaluation: Insights on B.O.P. importance Future B.O.P. regulations Auxiliary Feedwater/ Emergency Feedwater System Review c.

- Description of review

- BWOG Findings (Sumary of Acceptability of EFW InitiationandControlSystemforeach88WPlant)

- Staff Evaluation d.

Secondary Plant Relief System Review 2

~

^*

- Description of review

~

- BWOG Findings

- Staff Evaluation e.

Instrument Air System Review

- Description of review

- BWOG Findings

- Staff Evaluation i

l' (15 Min.)

BREAK 4:00 p.m.

4:15 p.m.

8.

EvaluationofHumanFactorsIssues(Staff /BWOG)

(45 Min.)

j a.

Des:ription b.

Areas of SPIP

- Operator / Maintenance Personnel Interviews

- Operating Experience Reviews

- Procedures and Training Reviews

- Sensitivity Analysis / Operator Burden Project

[

i c.

Conclusions /Recomendations d.

Staff Evaluation l

RECESS 5:00 p.m.

i r

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1 I

3-7 I

3,

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Wednesday, May 4, 1988 8:30 a.m.

9.

EvaluationofOtherBWOGReports(BWOG/ Staff)

(30 Min.)

a.

Arming Threshold for Anticipatory Reactor Trip b.

Setpoint for Reactor Trip on High Pressure c.

Evaluation of Turbine Generator-Caused Reactor Trip d.

BWOG 1154 Task Force Report e.

Staff Evaluation 9:00 a.m.

10.

RiskAssessment(BWOG/ Staff)

(1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />) a.

Background

b.

BWOG Evaluation c.

BNL Assessment of BWOG work / Independent Assessment d.

Conclusion /Recomendation (15 Min.)

BREAK 10:00 a.m.

10:15 a.m.

11.

Reactor Trip Initiating Events Review (45 Min.)

(BWOG/ Staff) a.

Description of Review b.

BWOG Conclusions and Recomendations c.

Sumary of Staff findings 11:00 a.m.

12.

BWOG Programatic and Management Actions (30 Min.)

l (BWOG/ Staff)

Safety and Performance Recomendation Integration a.

Group l

b.

BWOG Evaluation Progran to Assess Quality of Implementation of the SPIP Reconrendation j

i c.

Staff Evaluation 11:30 a.m.

13.

ImplementationofSPIP(BWOG/ Staff)

(15 Min.)

i a.

Description of Recommendation Approval Process b.

Implementation of Recomendations

- Prioritization of recomendations

- Schedules 4

s o.

'd Impact Assessment of Proposed Recomendat c.

d.

NRC Audit of Process Additional Concerns Identified by an NRC Staff (45 Min.)

12:15 p.m.

14.

Member (D.Basdekas) a.

Sumary of Concerns b

b.

Actions Sought Response by Staff Management c.

d.

Discussion of Issues (15 Min.)

1:00 p.m.

15.

ClosingRemarks(ACRS)

Schedule for Full Cunnittee Presentation a.

Thursday, May 5, 1988 1-4 p.m.

Additional Actions De-med Necessary b.

Possibility of a Letter to the NRC c.

ADJOURN 1:15 p.m.

5-