ML20127C667

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Forwards Fax Sent to J Duncan,Ge That Updates Status of Advanced BWR PRA Issues
ML20127C667
Person / Time
Site: 05200001
Issue date: 12/01/1992
From: Kelly G
Office of Nuclear Reactor Regulation
To: Poslusny C
Office of Nuclear Reactor Regulation
References
NUDOCS 9301140291
Download: ML20127C667 (14)
v • d • e


Text

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December 1, 1992 liOTE TO: C(et[Poslusn///,NRR-

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FROM: G,lefgMy W DSSA, liRR SUBJECl: FAX FROM GE/ FAX 10 GE i

I have enclosed a fax 1-sent to Jack Duncan, GE that updates the status.of ABWR PRA issues. 1 aTso nove coulus h -fur sent-te T.c by Jack-Duncan-o+s LAC 4&-tmWtttemf cDD t u i w;+n t .

Enclosure \: as stated -

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T The following chart is a summary of the status of issues raised by the staff

' - concerning the ABWR PRA. This chart has been coordinated with GE to assure that it is as accurate as possible in portraying issue status. The chart is current as of November 30, 1992.

An issue is judged " confirmatory" in the chart if GE has submitted (by fax, discussion, meeting handout, or letter) sufficient information for the staff to draw its conclusion regarding the issue.- Most of the information submitted by GE has been provided in a preliminary form. All information must be translated by GE into SSAR modifications that capture issuc resolution.

An issue is judged to be "open" in the chart if the staff is awaiting GE's response on staff questions or if the staff still has the issue under review.

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SIALUS OF_ABWR_B A_ ISSUES November 30, 1992 IS.5MLD151RifilpN .11MllS_ ACIJ.ON G0NE21LtiMPRY I$ SUES

1. RPS Reliability 0-1
2. GE to update ECCS FT-1A - IB and other fault trees
3. GE to defend 10RV S-2 frequency
4. GE to defend 10RV C-1 success criteria
5. GE to defend one S-1 unplanned trip per year
6. GE to evaluate 0-2 support system failures as initiating events
7. GE to confirm LOSP l-1 ,

frequency and other site-specific parameters

8. Confirm A1WS success C-2 criteria
9. Confirin RHR success SC-1 criteria
10. GE to justify CCF C-3 data -
11. GE to justify 0-5 train-level CCF approach is adequate
12. GE to justify test C 4A l' and maintenance data l analysis 13._GE to perform CDF C-4B sensitivity to outage times and surveillance l

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14. GE to justify RHR, 0-6 dPCF pump failure data
15. GE to correct S-Il credit taken for fire water
16. GE to provide write 0-22a, 0-228 up on PRA as a design tool
17. Staff questioned S-5 TO S-8, 1-14 seismic capacity of the following equipment:

fuel assembly, flat-bottom tank, diesel generator, electrical equipment

18. Staff proposed use S-10 of LLNL hazard curves
19. GE to address SA-1 hazard curve uncertainties
20. GE to confirm 1-10, 0-218 seismic capacities of equipment and incorporate into design specifications ,
21. GE to modify I-11 seismic PRA to account for soil structure

- failures

'22. GE to commit COL' l-12 applicant to a specific seismic walkdown technique.

i 23. GE to commit COL. 1-13 applicant to perform a site-specific seismic PRA I

24..GE to correct the .S-3 treatment of firewater L in the Seismic Class 11 I

CET

._- ._ . .___ _ _ ._.. . ~ . . _ ._. _ _ _ _ ._ .. _ -.._ _ _._. _ _ . . _ _ _ _ - - _ _ ._ _

25 GE to link PRA IN-1

'; " requirements" and .

insights to " Interface ,

write up" ,

26. GE to submit a fire 0-12 PRl,
27. Determine if CETs 0-13B need to address wetwell-drywell bypass
28. hodify CETs for 0-17A, -178 severe accident phenomena
29. Flashing during C-6 venting
30. Justify aspects of 0-14 rupture disc set point
31. Assess the impact structural calculations 0-16A, 0-18E.

of CCI on containment under review by ECGB and integrity are not a PRA issue.

32. Assess the impact 0-168, 0-18E.

of CCI on source terms 33.Dncertainty 0-18A, -18B, -16C

. Analysis Identify risk '

significant issues from previous BWR studies Screen issues for applicability tc

. ABWR

34. Rupture disc S-9 operation before 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> -
35. Treatment of ATWS In the DSER, ATWS was S-12 as a late containment treated as an-early failure in CET analysis containment failure in the staff's assessment..

However.-the staff recognized in the DSEP that this should be corrected.

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. i 36, GE to provide 0-18A, 0-11 ,

1evel-1 PRA uncertainty analysis -

37. Drywell Sump (SCSBissue)BA-3 penetration by corium
38. Credit for COPS S-4 '
39. Drywell Head BA-1 (Bagchi)

Ultimate Strength

40. Service level C for BA-2 (Bagchi)

Containment

41. Consequence CA-3 .i Analysis '
42. EP7 Consequence CA-4 Analysis
43. Consequence CA-1 Analysis and Site '

Acceptability -

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IS$UE DESCRIPTION STATUS ACTION OflLLUUD

1. GE needs to take its GE has submitted only a few GE's action to informal sebmittals and of the SSAR updates. Staff submit followed by write them up in the expects GE to provide the staff's review SSAR. majority of its SSAR of these submittals.

updates on PRA issues in December 1992 and January -;

1993.

2. GE is to analyze GE's previous submittals on GE submited LOCAs outside of these LOCAs were not reanalysis on ll/S.

contair' '

s (0-4) acceptable to the staff or This analysis also the ACRS. GE and the staff is to address bypass  !

have discussed what needs potential for to be submitted. drywell purge and inceting lines (19E.2.3.3). Staff  ;

is reviewing. 0-4B

3. RWCU as a high ACRS identified concerns GE to submit pressure DHR source with GE's design and requested assumptions. GE has agreed information. No to "make the PRA come date has been true." The staff is provided by GE, but '

awaiting information on it should not be isolation signals that protracted. SC-2 could isolate the entire RWCU. GE has submitted preliminary modifications to the RWCU to allow itsto remove decay heat at high pressure. GE has RWCU-related COL action items to add to its SSAR.

4. GE is to list Outstanding questions GE to submit. 0-21A assumptions / reliability include listing of systems values for systems that important to safety but not are not part of the modeled in PRA; Systems certified design, but modeled in PRA but not part are modeled in the PRA of Design Certification (e.g., UHS and Reactor Service Water Pump House);

Awaiting reliability assumptions for those systems modeled in'PRA.

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5. GE to requantify PRA GE has submitted its GE to submit.

, based on an up-to-date updated requantification. Should not take GE a plant model There are a series of long time to questions outstanding complete. PRA-1A related to this submittal.

6. GE to provide GE has not provided seismic GE to submit. No seismic capacities of capacity figures for the date given, systems not in the Reactor Service Water Pump certified design House.
7. Uncertainty Analysis GE to provide data on GE to provide

- Treatment of wetwell- applicability of vacuum additional drywell bypass in CET breaker operating information to experience data to ABWR support vacuum (10/27/92). GE provided breaker leak test ordering of top events in data. 0-10G CET on 11/3.

8. Severe Accident The significance of steam Based on 10/1/92 Closure explosions in ABWR is meeting, GE to (1) reduced by having a dry reassess the cavity at the time of potential for vessel failure. Additional flooded cavity at information on the vessel failure and frequency of a flooded (2) provide cavity was requested during chronology for 10/1/92 meeting to support additional cases closure of this issue. reported in SSAR (This information was not provided in the November 3, 1992, Fax). NRC-1 e

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9. Accident management Staff evaluation provided GE to develop and to GE in draft Severe submit additional Accident Closure chapter. guidance for COL GE's planned response applicant on aspects discussed 10/5/92. of ABWR design which should be addressed ,

by applicant in developing their accident management plan. NRC-2

10. SAMDA submittal Revised SAMDA analysis GE to modify

- submitted 6/30/92 and submittal to address discussed with GE 10/8/92, concerns discussed during 10/8/92 meeting. NRC-3

11. Containment GE has proposed to address GE to reevaluate isolation failure this issue by extending seismic issue after during seismic event analysis of LOCAs outside completing analysis c.ontainment (19E.2.3.3) to . of issue for seismically-initiated internal events, events. The approach for Now being addressed analysis of LOCAs outside as part of revised .

containment (for internal seismic margins events) was subsequently analysis. (0-4,0-rejected by staff and is 19) now being addressed as issue 0-4.

12. AC Power Recovery GE submitted .

reassessment of 0.6 value assumed for probability of recovering AC power on 11/3/92.

13. GE to provide PRA GE still has to provide a insights discussion of balance of prevention and mitigation, improved discussion of vulnerabilities.
14. GE to provide decay The staff has sent GE a 0-20

. heat removal list of formal questions, reliability study y , ,m-- - e ~, - . , , - - - -,-% .- -,

. analysis the effect of high pressure pipe breaks on the walls between divisions.

Analysis expected from GE in mid-December.

16. Human factors in GE made related submittals GE to provide PRA (C-5, 0-7 thru 0- on sentitivity of CDF to response. C-5 to I-10, 1-2 thru l-7) human error (10/16/92 and 7 6/1/92), identification of human errors in Level 1, level 2, and seismic analyses (6/25/92), and PRA data uncertainty analysis (6/18/92). Staff requested additional information on 10/27/92.
17. GE to provide PRA- The staff has discussed The staff i1as based seismic margins with GE its concerns with transmitted guidance analysis the ABWR seismic margins on performing a PRA-submittal and has based margins transmitted questions to analysis for GE. GE has responded by evolutionary fax and meeting handouts to designs. SA-2 many of these questions. ,
18. GE to provide PRA- GE has submitted its The staff has based input to ITAAC version of PRA-based ITAAC transmitted its insights. comments to GE on

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.19. Site specific The staff's draft SECY The staff's action design verification: paper on Design is to modify the i external floods,- Certification and Licensing siting criteria for transportation hazards Policy issues Pertaining to the ABWR since no i Passive and Evolutionary site-specific  !

Advanced Light Water external flooding  ;

Reactor Designs states that analysis has been 10 CFR 52.47 requires the provided. The '

analysis of both internal siting criteria will and external events. At exclude sites where the Design Certification it would be possible stage, site-specific events for external floods such as tornadoes and to exceed the height i extreme wind may be of the site grade enveloped using bounding level and where analyses to show that the other non-enveloped ,

events are insignificant. external events are i in performing the COL a threat. GE i review, the staff will. believes that it review the site-specific need not take any characteristics to ensure action at this time.

that events enveloped by I-8 the bounding analyses have been properly addressed.

20. Net risk impact of GE confirmed passive flooder system (11/3/92) alloy mixtures to be used in passive flooder 2

valve. 0-15

21. Backend Uncertainty Staff to complete Analysis - Perform review. 0-18C sensitivity analyses for issues of potential -

risk significance to

22. Uncertainty Staff to work with Analysis - Treatment of BNL contractors to CCI coolability in CET address risk significance of issue in FSER. (0-18E,0-16) 4

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23. Onesrtainty GE to provide
  • Ar.alysis - Treatment of justification that direct containment reactor heating in CET depressurization system is highly reliable during seismic events (CEB92-41-2). GE submittal on 11/3/92 only partly addressed this. GE still has to address reliabiltiy/

vulnerability of ADS function in seismic.

Also has to address wetwell spray availability and containment response.

Based on 10/1/92 meeting, staff to review information '

provided in 19E.2.1.2.2 re:

ability to depressurize Class-IB sequences. Staff to document evaluation in FSER.

0-18D >

24. Consequence related Significant differences Staff to work with issues (CA-1,2,3) observed between BNL and GE BNL contractors to consequence calculations reflect differences for apparently similar between codes.in source terms were noted FSER, during 10/1/92 meeting.

Based on follow up

  • discussion on 10/28/92 differences appear to be due to use of MACCS versus CRAC2.

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25. GE is to analyze The Reactor Systems Branch SRXB. 0-3 interfacing LOCAs is not satisfied with the resolution prcposed by GE -

for its upgrading of low pressure system piping.

This issue will remain open until GE/ staff agree on upgrade criteria and the staff PRA people can. review it to determine.if the resolution has any negative effect on its conclusions.

GE has submitted its proposed resolution to this issue.

26. GE to compare PRA GE's original submittal GE submitted its sequences from discussed this in write up. Under operating BWRs to the generalities. The staff staff review. 0-1B ABWR PRA sequences and wants a comparison of identify why ABWR has sequences with an lower CDF explanation of why the ABWR design results in such significant C0F reductions.
27. GE to use PRA GE submitted its revised Under staff review, insights to suggest RAP input on November 11, I-)5 ,

areas to be added to 1992. Rest of revision due the ABWR reliability 12/4/92.

assurance program e

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The followino are SPSB issues

28. Fuel-Coolant Staff pursuing independent Interaction analysis of FC explosion.
29. Core Debris HACEIBhadheatfluxps Coolability/ Core greater than 100 kW/m for Concrete Interaction first nine hours. Staff ex1auating less than that for upper heat flux. Steff evaluating sump design.

Pedestal structural integrity under discussion.

30. Containment Bypass Severe accidents demonstrated .6f t',with fire water. 0.lft demonstrated w/o fire water. GE to document further information on DBA analysis.
31. Compliance with EPZ CA-6 Emergency Plan Criteria and Methodology O

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