ML20237G092
| ML20237G092 | |
| Person / Time | |
|---|---|
| Issue date: | 08/06/1987 |
| From: | Morris B NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Gavigan F ENERGY, DEPT. OF |
| References | |
| PROJECT-672A NUDOCS 8708130306 | |
| Download: ML20237G092 (10) | |
Text
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l August 6, 1987 Mr. Francis X. Gavigan, Director Office of Advanced Reactor Programs Office of Nuclear Energy V. S. Department of Energy Washington, DC 20540
Dear Mr. Gavigan:
On July 15 and 16, 1987, members of the NRC staff and its contractors from 0RNL and BNL met with representatives of DOE and its contractors to review the Emergency Planning Bases Document and the Probabilistic Rim' Assessment for the Modular HTGR, Project 672.
In addition, information was presented performed by NRC contractors, and (3) perator, (2) independent safety analyses and discussed on (1) the role of the oaccidents beyond the licensing bassa.
The list of attendees and the agenda are given in Enclosures 1 snd 2, respectively. The Action Items and Clarifications (including requests for additional information) resulting from this meeting are given in Enclosure 3.
Your response to these items is requested by August 28, 1987, in order for us to maintain our current review schedule This meeting concludes, in accordance with our agreed upon schedule, the series of meetings planned for NRC review of the PSID and other documents pertaining to the conceptual design of the MHTGR. We are proceeding to prepare a Safety.
Evaluation Report for the MHTGR.
In the course of our preparation, we expect it will be necessary for us from time-to-time to have additional meetings with 1
DOE and its contractors on selected topics and/or request additional j
information. We will contact you as these needs develop.
If you have any questions please do not hesitate to contact Dr. Peter Williams, j
the Project Manager for Project 672.
Sincerely, j
i Bill M. Morris, Director Division of Regulatory Applications-
Enclosures:
- 1. List of Meeting Attendees
- 2. Agenda
- 3. Action Items and Clarifications
- See previous concurrence.
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- 2. Rosztoczy T. King i
J. N. Wilson C. Allen
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J. Flack j
R. Baer N. Anderson F. Cherny j
S. Shaukat j
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D. Thatcher 1
J. Hulman J. Glynn L. Soffer l
J. Read D. Clearv I
A.Murphf G. Arndt R. Kirkwood M. Lamastra R. Erickson I
B. Mendleschn H. VanderMolen
.E. Che11ich L. Beltracchi F. Congel J. Swift O. Lynch D. Matthews R. Senseney M. Spangler F. Coffman S. Ball, ORNL P. Kroeger, BNL G. VanTuyle, BNL R. Ireland, Reg. IV M. El-Zeftawy, ACRS/H-1026
- PDR - Project 672 Project File 672'(Centrs1' Files)v
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Enclosure.1 Attendees NRC/ DOE Meeting on MHTGR j
July 15 and 16, 1987 J
P. M.. Williams NRC/RES/ARGIB 492-9613 E. M. Podolak*
EPB/NRR 492-7290 Syd Ball ORNL (615) 574-0415 Tom King NRC/RES 492-7014 Jim Glynn NRC/RES 443-7630 John H. Flack NRC/RES 443-7767 Peter G. Kroeger BNL (516) 282-2610 Jerry N. Wilson NRC/RES/ARGIB 492-4727 L. Walter Deitrich ANL/EPRI (312) 972-4571 l
Gayle Cadwallader-GA Technologies (619( 455-3309 S. B. Inamati GA Technologies (619) 455-4331 Larry Parme GA-Technologies (619) 455-4555 David M. Zizzo*
GE-NST0 (408)'365-6409 Jim Quinn*
GE-ANT (408) 365-6576 Gordon W. Dean DOE (415) 273-7917 Jacques Read
- NRC/RES/SAIB 492-4958 Irwin Spickler*
NRC/NRR/DRP 492-4084 Tony Neylan GA (619) 455-2580 Fred Silady GA (619) 455-4320 John C. Cunliffe Bechtel (415) 768-2227 Donald V. Graf MHTGR-PDC 0 (619) 455-4294 F. X. Gavigan DOE-HQ 353-3134 A. C. Millunzi DOE-HQ 353-3405 l
Dan Mears GCRA (619) 455-9500 l
J. M. Kendall GCRA (619) 455-9500 i
L. P. Walker SWEC/GCRA (619) 455-9500 Leo Beltracchi NRC/RES 492-8048 John M. Oddo SWEC (617) 589-7403 Paul R. Kasten ORNL (615) 574-6093 Carmelo Rodrigvez GAT (165) 574-6093
-l B. M. Morris **
NRC/RES 443-7936.
R J. W. Minarick**
SAIC (615) 482-9031 i
l E. Chelliah**
NRC/RES/PRAB 492-8048 Cardis Allen **
NRC/RES 492-8302 George Sherwood**
DOE FTS 233-4162 Richard E. Johnson **
NRC/RES/GIB 492-8129 i
Miller B. Spangler NRC/0NRR 492-8217 i
- Indicates attendance on July 15,.1987 only.
_** Indicates attendance on July 16, 1987 only.
1
6 Part 1 AGENDA
.NRC/ DOE MEETING ON MHTGR REVIEW JULY 15,'1987 ROOM P-118 1
9:00 - 9:10 OPENING REMARKS NRC/ DOE /0THERS 9:10 - 10:00 OVERVIEW:
CHAPTER 13.1 AND EPBR GAT
- Ob.iectives l
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- Background l
- Comparison to Regulatory Precedence l
- Approach to Emergency Planning Bases 1
10:00 - 10:30 LICENSING BASIS EVENTS FOR EMERGENCY PLANNING GAT
- Selection of LBEs for Emergency Planning l
l 10:30 - 10:45 BREAK i
L 10:45 - 11:45
- Description of Emergency Planning Basis Events GAT l
- Radionuclides Sources, Release and Doses
- Response to NRC Questions 11:45 - 12:^0 EMERGENCY PLANNING ZONE GAT l
- Assessment of Plume Explosure Pathway Doses L
- Selection of Plume Exposure Pathway EPZ l
- Discussion of Emergency Planning Implicatoins
- Response to NRC Questions 12:30 - 1:30 LUNCH l
1:30 - 3:30 ROLE OF THE OPERATOR NRC/ DOE /GA/GE i
- Goal of Presentation
- Design Approach
- Goals, Functions, Reqid ements, Selections
- Automation Assessments 'uperator Interfaces
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- Conclusions 1
3:30 - 3:45 BREAK 3:45 - 5:00 PRESENTATION AND DISCUSSION OF ORNL/BNL INDEPENDENT ANALYSES I
a..
l Part 2 AGENDA-
,1 NRC/ DOE MEETING ON MHTGR REVIEW JULY 16, 1987 ROOM P-118 8:30 - 9:00 INTRODUCTION NRC/ DOE /0THERS 9:00 - 10:30 OVERVIEW GAT l
Objectives of Briefing Objectives of MHTGR PRA-Scope and Dimensions of the PRA Description of the PRA Document Conclusion from PRA 10:30 - 10:45 BREAK
.j
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10:45 - 12:30 PRA BACKGROUND AND METHODS GAT Background & Previous Experience
- External Events
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- Internal Initiator Plant System & Component'and Fault Tree Development Frequency Assessment Methods including Human Actions Radiological Consequence Methods t
Uncertainty Assessment Methods 12:30 - 1:30 LUNCH 1:30 - 2:30 REACTOR CAVITY COOLING SYSTEM BNL' 2:30 - 4:00 ACCIDENTS BEYOND LICENSING BASES
- Reactivity Transients GAT
- Conduction Cooldown w/o RCCS BNL/ GAT
- Large Steam Ingress CE/ GAT:
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- Large Depressurization CE/ GAT
- Seismic Failure of Core Support
- Large Failure of Cross Duct j
4:00 - 4:30
SUMMARY
AND CLOSING REMARKS GAT /GCRA/ DOE.
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ENCLOSURE 3 ACTION ITEMS AND CLARIFICATIONS FROM NRC/ DOE MEETING, JULY 15 AND 16,.1987 ON MHTGR EMERGENCY PLANNING BASIS DOCUMENT, PRA AND OTHER TOPICS
GENERAL COMMENT
S G-23 DOE will modify the Emergency Planning Basis Document to incorporate information presented at the July 15, 1987 meeting.
This will include (1) incorporation of the functional analysis diagram, (2) a description, to the extent possible at this time, of l
the actions to be taken as indicated in the diagram blocks entitled.
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" Notify General Public", " Notify Government Agencies", " Drill Govern-f ment Agencies", and (2) identification of emergency planning infor-matien that will be provided at future licensing stages.
G-24 The staff informed DOE that DOE's position on emergency planning;for the MHTGR was relatively clear, but its acceptance by the NRC involved a major policy decision that would be guided by the Commission itself, prior to the issuance of the MHTGR Safety Evaluation Report. The staff is preparing a paper.to the Commission on containment and severe accidents for advanced reactors that will
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include discussion of the emergency planning issue.
i G-25 The following comments pertain to the selection of the seismic design i
event as presented in the Emergency Planning Bases Document and derived from the PRA.
A.
In its discussion of Emergency Planning Basis' Event-3 (EPBE-3), (earthquake induced slow depressurization of all four reactor modules) DOE stated that it used applicable data from NUREG/CR-3558, " Handbook.of Nuclear Power Plant Seismic.
Fragilities", in addition to references cited in the PRA document.
DOE should be sware and make appropriate use of more recent and forthcoming data from NRC research
programs (e.g., UCID-20571, " Compilation of' Fragility Information from Available Probabilistic Risk Assessments" LLNL, September 1985, and NUREG/CR-4659, " Seismic Fragility of Nuclear Power Plant Components",-June 1986).
In addition,certain l
proprietary data are available from the NRC on request (without identification of its source) that might result in PRA improve-ments.
1 B.
'Of central interest to the staff's review of EPBE-3 is fragi11ty i
data for equipment unique to the MHTGR and' DOE's plans to i
acquire additional unique fragility data as maybe necessary. We request that DOE-sugment its Table C-1 in the FRA document with e
re d
u e (su h h
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differentiated from the system as a whole, the various sections j
of the graphite core support structure, and the support system l
for the steam generator vessel). A discussion should be included concerning the adequacy of the information presently available for each item and the plans to obtain additional data as the design progresses by such means as analysis, testing, or foreign information.
C.
The methodology used in the analysis of seismic events beyond the SSE should be more fully described. This methodology l
rssulted in event EPBE-3 for assessing large earthquakes; how-I ever, based on the information presented we cannot conclude l
l that EPBE-3 properly characterizes.the effects of seismic events beyond the SSE.The staff recommends that DOE address l
this concern by including verification.of selected aspects of the seismic design methodologies and component fragilities (particularly for graphites) in the Regulatory Technology j
Development Plan..
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G-26 The following comments refer to the staff's review of the MHTGR I
PRA:
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'A.
Although DOE stated that it believes the PRA to be adequate for the selection of licensing basis events, equipment classification, j
and to support the approach to emergency planning, it also state'd that the PRA was not the only basis. DOE should describe how other bases are used in conjunction with'PRA in making safety related decisions.
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B.
DOE stated that a reliability assurance-program will.be developed but it is not available for the present stage of f
I the MHTGR review. DOE should describe the scope and objectives of the program being considered and indicate its relationship to component reliability testing programs, also stated to be under development, and to the quality assurance, surveillance and maintenance programs which will be required for MHTGR licensing.
C.
DOE stated that as the MHTGR design evolves to more advanced stages, PRAs will be prepared commensurate with the i
design.
DOE further stated that the staff's current PRA review J
and expectations should consider that the PRA is for the conceptual design level rather than in support of a PSSAR.
D.
DOE stated that it concluded, after studies, that risks are dominated by plant conditions at the 100 percent power level. DOE should give examples of studies that led to j
this conclusion and the decision not to consider refueling, low pouer, startup, or shutdown conditions at this time in the PRA.
E.
DOE stated that it believes the PRA role of support systems and support system interactions is less important than for
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LWRs because passive systems dominate safety performance of-the MHTGR. DOE also believes for'this reason that modeling is simplified as is the level of modeling uncertainties.
mey--
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F.
DOE will provide a version of the " Dose-Risk Limit Chart" i
in which the uncertainty limits are included with the plotted accident points.
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G-27 DOE presented dose and risk estimates for accident events beyond the design bases to illustrate that the residual PRA risk is negligible. The estimates were provided or referenced l
for (1) large reactivity events (loss of forced cooling
.without scram, red ejection, complete control rod withdrawal, and large steam ingress), (2) conduction cooldown without RCCS, (3) cross duct vessel failure, (4) steam generator failure without isolation or dump, and (5) core support integrity considering a large earthquake. DOE will document this infor-mation in the PSID.
The staff believes this information to be highly valuable in assessing the overall safety potential of the MHTGR and it will continue to review this material by a com-bination of independent analyses and continued-dialog with DOE and its contractors.
l SPECIFIC COMMENTS l
4-40 DOE stated it would have available by mid August, 1987, a full understanding of reactivity coefficient uncertainties, particularly in connection with the build up of plutonium isotopes in the later stages of the fuel cycle. This material should be documented with'the scheduled August 28, 1987 response.
i 5-35 View-graph material made available but not presented on vessel system reliability should be summarized and incorporated into the PSID.
5-36 View-graph material made available but not. presented.on the' MHTGR steam generator reliability should be summarized and incorporated into the PSID.
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5-37 Material presented supporting a RCCS failure probability of
-6 lx10 per demand should be incorporated into the PSID. This l
should include documentation that an'unisolated steamline break j
will not result in cavity pressure levels causing panel collapse.
l Also, discuss the staff's concern that a materials failure near the top of the wall separating inlet and outlet sides of the panels could cause a short circuiting of the convecting air and thereby defeat the functioning of the RCCS.
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4 13-14 DOE should incorporate into the PSID the new material presented at the meeting supporting its conclusions that the role of the operator is limited to non-safety actions and that the control room and remote shutdown areas are not safety related.
The responsibilities of licensed operators as distinguished from other plant operating personnel,. including management, should be discussed.
DOE should also identify the major human factors principles to be applied in determining the licensed operators role and how success in performing this role can be assured.
13-15 DOE stated that the development of a fully automatic control system should be considered an " applications technology" rather than a " developmental technology".
In order to support its position that the Regulatory Technology Development Plan need not include automatic control as a development item, DOE wil1 provide a summary discussion of the status of automatic control in both the U. S. and foreign nuclear power industries, and the I
scope of the program to implement automatic control for the MHTGR.
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