ML20012E318
| ML20012E318 | |
| Person / Time | |
|---|---|
| Issue date: | 03/27/1990 |
| From: | Williams P NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Joshua Wilson NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| NUDOCS 9004030218 | |
| Download: ML20012E318 (6) | |
Text
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M R 2 7 1993 s
MEMORANDUM FOR: Jerry N. Wilson, Acting Chief Advanced Reactors and Generic Issues Branch, Division of Regulatory Applications. Office of Nuclear Regulatory Research FROM:
peter M. Williams, Advanced Reactors and Standardization Section, Advanced Reactors and Generic !ssues Branch, Division of Regulatory Applications, Office of Nuclear Regulatory Research
SUBJECT:
MEETING WITH DOE ON MHTGR DESIGN CHANGES AND TECHNOLOGY DEVELOPMENT On March 8, 1990 members of the NRC staff and its ORNL and BNL contractors met on the subjects of MHTGR design and technology development with DOE, its contractors, and Gas Cooled Reactor Associates (GCRA1. DOE contractors are the PlantDesignControlOffice(PDCO),GeneralAtomics(GA),BechtelNationalInc.
(BNI), Combustion Engineering (ABB/CE), and Stone and Webster (SWEC). A list of attendees is given in the Enclosure. The topics presented were f!) design updateschedule(2) equipment classification status, (3) water ingress, (4) plan and for the revision of the regulatory technology development program, (5) the reactor physics verification and validation program, (6) fuel performance and fission product transport status, (7) fuel process development status, and (8) the status of the reactor vessel elevated temperature code case.
Administrative matters discussed at the meeting were:
1.
AllYu-graghspresentedontechnicalmattersareconsidered" applied technology (AT). Therefore, they are not available for inclusion in this report.
2.
The DOE licensing plan is being reviewed by upper DOE management and will be submitted in a few months. The plan is expected to include submittal of a pSAR in late FY 1992. DOE will be following a two step rather than a combined license approach for the MHTGR.
3.
DOE considers this meeting the first of a series of meetings to prepare NRR and RES for submittal of the PSAR.
In addition, DOE will invite NRC to technical development meetings, the first of which will be at ORNL on fuel, April 17 and 18,1990.
4.
NRC stated its plans to issue the final Preapplication SER in November 1990. The final SER will address topics pertaining to the key licensing issues (i.e., containment, etc.) but will not address design changes or other information unless they pertain to the key issues. Most information i Q
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DOE will present in the future will mertain to readiness to review the pSAR and not to the many open issues in tie draft SER. As an example, changes in the helium purification system were described but these were not in accord with the SER's finding that this system should be classified as safety grade to permit emergency reactor depressurization.
5.
In response to a question, DOE stated that it plans to use data developed in the New production Reactor (NpR) - MHTGR arogram to the extent practical but that it was not dependent on t1is program. We suggested that the licensing plan or the revised technology development plan address this issue in detail.
l TECHNICAL DISCUS $10NS i
1.
Design Update (J.C. Cunliff, BN1; R.F. Turner, GA; G.F. Dilauro, CE) l Design changes described were:
(1) elimination of full cross connection between the four reactor modules and the two turbine generators - for
- ease of control" two reactors will now connect with a single T-G set, (2) RCCS tubing is now placed against the reactor cavity walls and appears sturdier but it is still designed for 10 psi external pressure, (3) most auxiliary cooling systems are now modular and the helium purification systems have been relocated, (4) neutron control assemblies (5) station batteries are adjacent are now air rather than water cooled, located (6) the steamline is now to each module rather than centrally largely in a separate cavity, (7) fuel particles now have an additional
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outer layer (low density graphite) to protect against coating cracking i
during fabrication into fuel compacts, (8) both structural and fuel block graphites are now a single grade Type H451, (9) modifications have been l
made to the seismic keys upper shroud, and the incore flux monitors, (10)bothmainandSCScIrculatorsarenowtwo-stage,ofaxledesign,and will use magnetic bearings, (11) changes were made in the steam generator as a result of normal design evolution and to permit incorporation of the new circulator inlet duct geometry.
The use of bimetallic welds will be retained because of water chemistry problems.
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DOE stated that, in general, no changes to functions and requirements were made and that design changes were made (1) to respond to further definition / extension of functional requirements (2) to improve reliability and/or efficiency, and (3) to reduce overall lifetime system i
costs. With the >ossible exception of the additional outer fuel particle coating none of tie design changes are expected to be reflected in the final preapplication SER, 2.
Equipment Classification Status (F.A.Silady,GA)
DOE is extending the use of the term " safety-related" to include equipment needed to meet the EPA Protection Action Guidelines (PAC's) as well as 10 CFR Part 100. DOE further stated that lack of classification as
" safety-related" would not imply that the equipment has no radionuclide control function and is outside NRC oversite.
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Steam / Water Ingress (F. A. Silady, GA) l l
ThesteamingresseventsdescribedinthePSID(SRDC6and7)and i
Appendix G.3 of the PRA were reviewed as well as the safety significance of ingress events on the following:
fuel (increasedtemperaturefrompower transients and hydrolysis), graphite (oxidation and strength loss), reactor vessel (reliefvalveopeningandwashoffofplatedoutradionuclides),and i
thereactorbuilding(combustiblegasgeneration). Discussion centered on the 1-131 release from exposed UC0 kernels in defective fuel particles. This radionuclide is the dominate source term and its release would occur in a time period of hours to days. An improved understanding of the hydrolysis phenomena is expected from the fuel research program, including further analysis of the completed ORNL capsule test HRB 17 and the results of capsule experiments in the Petten reactor in Holland.
f 4.
Regulatory Technology Development Program (RTDP)
(F.A.Silady,GA)
DOE reiterated its statement that the aim of its overall technology program, of which the RTDP is the safety subset, is to provide all experimental data for plant design and licensing and that no demonstration plant or special licensing tests will be required. The following schedule for submittal of sections of this document to the NRC for review was provided:
(1) fuel and fission products - 10/90, (2) graphite - 8/90,(6))RCCS - 6/90, (7)(4) control materials - TBD, (3 metals - 8/90 (5) physics - 4/90 other system and component technology - TBD.
5.
Reactor Physics Verification and Validation Plan (A. Baxter, GA)
The core physics design requirements were sumarized and uncertainty goals were listed. Related experimental studies and facilities were identified in both the U.S. and abroad but possible needs for new facilities were not indicated. DOE stated it was aware that Dr. John Askew of the U.K. had proposed to collect and review low-enriched critical experiment measurements obtained in the course of the development of gas cooled reactors in the U.K.
DOE hasn't yet decided if these data are needed.
Because of the unusual geometry of the MHGTR core a satisfactory reactor physics validation program may be difficult to achieve from existing data and facilities.
6.
Fuel performance and Fission Product Transport (0.M.Stansfield,GA)
Although progress has been made since submittal of the PS10, lack of full funding and a 3-year shutdown of HFIR at ORNL has resulted in a 2 to 4 ear delay in developing required data. The scheduled meeting at ORNL y(April 17 and 18) will supply detailed information as well as an updated fuel performance report to be issued shortly (HTGR-85 107. Rev 1).
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7.
Fuel Process Development Status (R.F. Turner,GA)
Objectivesare(1)todemonstratethatfuelparticlesandcompactscanbe manufactured with low defect levels at high production rates and (2) to fabricate fuel components for qualification and validation tests which support licensing and risk assessments. The OA/QC programs for kernels and coatings were said to be proceeding satisfactorily but further development was needed for compact manufacture.
8.
Status of Reactor Yessel Code Case (C.L.Hoffman,CE)
The inquiry for elevated temperature vessel service has progressed to the point where all information necessary for a decision will be submitted to the ASME by 5/90.
It would aspear that the potential operating lifetime could be improved substantially if credit was taken for the capability to depressurize.
Peter H. Williams Advanced Reactors and Generic Issues Branch Division of Regulatory Applications l
Office of Nuclear Regulatory Research
Enclosure:
List of Attendees NW
- See dist ibutj on next page Offe: ARGIB:DRA Mil :DRA:
Name PWilliams:rgJW Lnon 3/A/90 Date: 3/f790 b
0FFICIAL RECORD COPY
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i ATTENDEES i
MHTGR MEETING - NRC/ DOE AND CONTRACTORS 1
Name Organization Phone Peter M. Williams NRC/RES/ARG1B
?01-492 3736 Syd Ball ORNL 615-574-0415 i
Jerry Wilson NRC/ARG1B 301-492-3729 Richard E. Johnson NRC/RES/ElB 301 492-3909 John C. Cunliffe BECHTEL 415 768-2227 0.M."Stan* Stansfield ORNL 615-576-2211 i
Peter Kroeger BNL 516 282-2610 i
R. R. Mills PDC 0 619-455-4292 A. C. Millunzi DOE 301-353-3405 J. M. Kendall GCRA 619-455-9500 H. Jones ORNL 615-574 6092 T. C. Arthur ORNL 202-463-5066 Salne El Sefwany DOE / SAN a15-273-6443 i
Joseph Nawarelsk SWEC 617-589-5350 F'
Alan Baxter GA 619-455-2874 Richard F. Turner GA 619 455-2306 i
Fred A. Silady GA 639-455-4320 G. F. Dileuro ABB/CE 203-285-3176 C. L. Hoffmann ABB/LE 203-285-49?.9 i
A. H. Hsia NRC/NRR 301-492-1081 t
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