ML20205D134

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Proposed Summary of ACRS Subcommittee on Advanced Reactor Designs 870204 Meeting W/Nrc,Ga Technologies,Ge & Rockwell Intl in Washington,Dc Re DOE Advanced non-LWR Designs Concerning Use of Proven Technology & Standardization
ML20205D134
Person / Time
Issue date: 02/10/1987
From:
Advisory Committee on Reactor Safeguards
To:
Advisory Committee on Reactor Safeguards
References
ACRS-2488, NUDOCS 8703300339
Download: ML20205D134 (11)


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atgepr DATE ISSUED: 2/10/87 a/n 7 PROPOSED MEETING

SUMMARY

FOR THE ADVANCED REACTOR DESIGNS SUBCOMMITTEE MEETING ON FEBRUARY 4, 1987 - WASHINGTON, DC PURPOSE:

The Subcommittee on Advanced Reactor Designs met on February 4, 1987 in Washington, DC, to review DOE advanced non-LWR designs regarding the use of proven technology and standardization. In addition, the Subcommittee discussed a draft Commission paper prepared by the NRC Staff regarding standardization of advanced reactor designs.

ATTENDEES:

ACRS NRC STAFF M. Carbon, Chairman R. Colman J. Ebersole, Member T. King C. Mark, Member P. Williams P. Shewmon, Member C. Siess, Member OTHERS M. El-Zeftawy, ACRS Staff A. Tabatabai, ACRS Fellow W. Bickford V. Boyer GA TECHNOLOGIES J. Cunliffe G. Davis A. Neylan D. Mears A. Mullinzi GENERAL ELECTRIC J. Recknagel J. Scarborough N. Brown K. Unnerstall B. Genetts ROCKWELL INT.

J. Brunings R. Lancet MEETING HIGHLIGHTS, AGREEMENTS, AND REQUESTS:

1. Dr. Carbon, Subcommittee Chainnan, introduced the members of the Subcommittee and stated the purpose of the meeting. He indicated that DOE and its subcontractors are currently developing the DESIGNATED ORIGINAL 33 PDR Coctified Dy ( d d[

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a Advanced Reactor Designs Minutes February 4, 1987 designs of three advanced reactors (one gas-cooled, and two liquid metals). In early 1984, DOE requested the NRC to provide guidance to the designers, early in the design, prior to any formal appli-cation regarding the requirements for the licensability of the design. The ACRS agreed and urged for such early interaction. The

NRC agreed and a schedule for collaborative effort was established.

Preliminary Safety Information Documents (PSIDs) have been prepared by DOE and its contractors on each of the three designs and were submitted to the NRC for review in September (HTGR) and November 1986(LMRs). The PSID is basically a description of the conceptual design, including proposed licensing criteria and safety analysis to illustrate plant response to accident conditions. PRA and a description of the supporting R&D programs are also to be provided for each of the designs. The output of the NRC Staff's review of 4

the PSIDs would be a Safety Evaluation Report (SER) on each con-cept, giving guidance on the licensing criteria to be applied and the potential of the designs to meet those criteria.

The NRC Staff intends to prepare and submit Commission papers on three topics: (a) Standardization,(b)SevereAccidents,and(c)

Containment.

In accordance with the Commissioner's advanced reactor policy statement, which states that the ACRS should be involved early in the review, the Staff has asked the Subcommittee to review and l

provide comments on each of the three topics. In addition, the i

Staff has asked the Subcommittee to review other key issues (e.g.:

! non-safety grade control room, control of multimodular plants, and proposed use of metal fuel instead of oxide fuel for LMRs).

l Dr. Carbon emphasized that there are large differences between the new conceptual designs being presented and conventional LWRs, and

. r-Advanced Reactor Designs Minutes February 4, 1987 urged the Subcommittee to be prepared to accept the absence of some of the safety features present on other designs.

J II. Mr. Tom King, Section Leader-Safety Program Evaluation Branch /NRR, described the three DOE sponsored advanced reactor concepts. All three advanced reactor programs have as their objective the devel-

opment of a standardized plant design which would be submitted to the NRC for design certification and approval. Mr. King indicated
that the advanced reactors designs have unique characteristics, j namely

4

  • The concentration of safety functions in the nuclear island of the plant, 3
  • The use of modular reactor designs, including extensive shop fabrication of the modules, and provisions for staggered on-site module installation and operation, 4
  • Less operating experience to support the designs as compared to LWR, and
  • Varying degrees of design detail planned for submittal for certification.

Due to these unique characteristics, the NRC Staff is raising

. several key issues regarding what the NRC should require in order to certify a new reactor concept. These issues can be stated in the form of questions as follows:

(1) What plant systems, structures and components should be reviewed to be able to certify the design?

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Advanced Reactor Designs Minutes February 4, 1987 (2) What level of design detail should be provided for review on those systems, structures and components provided for certi-fication?

(3) What level of operating experience, existing technology and supporting R&D is required to support certification (i.e., is a prototype plant required to be built and operated prior to designcertification)?

(4) What information should be provided to allow flexibility in the design certification for variations in plant size (i.e.,

number of modules)?

(5) Is a manufacturing license (10 CFR 50, Appendix M) required prior to shop fabrication of reactor modules.

III. Mr. A. Neylan, GA Technologies, described the Modular High-Temperature Gas Cooled Reactor (MHTGR). The MHTGR plant design is a 350 Mwt standard reactor module being developed in conjunction with Gas Cooled Reactor Associates, Stone & Webster and Bechtel.

In March 1985, the side-by-side steel vessel concept was selected as the reference design to be further developed. In August 1985, the concept using prismatic fuel was selected for further develop-ment. The prismatic fuel option uses four modular, steel vessel reactors in the side-by-side configuration, each operating at a power level of 350 Mwt and supplying steam to two turbine genera-tors. The net plant electrical output is 558 Mwe. Each reactor module is housed in a vertical cylindrical concrete enclosure that is fully embedded and below grade. The nuclear island portion consists of four reactor enclosures and adjacent structures that house fuel handling, helium processing, and other essential reactor service systems. A common control room is used to operate all four reactors and the turbine plant. The design has no containment. A

5 Advanced Reactor Designs Minutes February 4, 1987 confinement system is used in the design. The design-utilizes active systems for nomal decay heat removal and reactor shutdown.

Passive means are provided as backup for accomplishing these functions.

Mr. A. Mullinzi, (DOE), stated that the major items that DOE considers safety related are the reactor vessel and its internals, the associated primary pressure boundary and the passive decay heat removal system. It is currently DOE's intent to request Design Certification on the entire Nuclear Island (which includes all safety related systems) and some of its key interfacing systems.

The remaining systems (which includes the balance of plant) would then be defined by interface requirements in the application for design certification. DOE's plan is not contingent upon a proto-4 type reactor module or the first commercial plant being built and tested prior to receiving design certification.

1 IV. Mr. N. Brown, General Electric Company, described a 425 ht modular liquid metal reactor called the Power Reactor Inherently Safe Module (PRISM). This concept emphasizes inherent safety charac-teristics and modularity. The reactor modules are a single stan-dard design that would be built in a factory and are shippable by rail as a unit. The plant uses nine PRISM reactors, with each 7

module producing 425 ht power. The plant combined power output is l 1245 Mwe. Each module is a pool type LMFBR design with its own I intermediate heat transport system and steam generator system. The PRISM reactor core is a homogeneous with U/Pu/Zr metal fuel similar I to that used in DOE's EBR-II reactor. The core lattice is being selected to be capable of breeding. The core and fuel design have the capability of mitigating anticipated transients without scram.

, The small size of each reactor module facilitates the use of i

i passive inherent self-shutdown and shutdown heat removal features.

J Advanced Reactor Designs Minutes February 4, 1987 The balance of plant (B0P) is completely disconnected from the primary loop safety considerations.

The containment vessel is located close to the reactor vessel to assure that primary coolant leaks from the reactor vessel do not result in loss of core cooling. GE's intent is to request design certification on only those portions of the plant which are con-sidered safety related. The remaining systems (e.g., control room, steam generator, B0P, etc.) would then be defined by interface requirements. The application for design certification would contain three options: (a) a three module plant, (b) a six module plant, and (c) a nine module plant. GE's overall plan includes construction and testing of a full scale prototype reactor module.

V. Mr. R. Lancet, Rockwell International (RI), described a 900 Mwt liquid metal standard reactor module called the Sodium Advanced Fast Reactor (SAFR). Sodium is the primary coolant, with a pool type primary system and passive decay heat removal. The reactor vessel is located above grade. The fuel is U/Pu/Zr metal similar to that used in DOE's EBR-II reactor. Each module is designed to produce 350 Mwe. RI envisions four 350 Mwe modules per site. Each SAFR module will use a building block approach with discrete increments of power generation called power packs. The SAFR plant will be designed to be comercially competitive with coal and LWR plants by the year 2000 and beyond. RI claims that radioactive releases during accident conditions will be low enough that no offsite evacuation plans are required.

RI's intent is to request design certification on all systems, structures and components (safety related as well as non-safety related)exceptsitespecificitems. The application for design certification would contain four options: (a)aonemodule,(b) two modules, (c) three modules, and (d) four modules plant. RI's l

2-Advanced Reactor Designs Minutes February 4, 1987 overall plan calls for the construction and testing of the first commercial unit prior to receiving design certification.

VI. Mr. T. King, NRR, pointed out that the standardization of advanced reactors poses several unique issues not faced in the standardi-zation of current generation of LWRs. Criteria for resolution of the five issues (described in item II above) are being proposed by the NRC Staff as follows:

Issue #1 - Extent of design to be certified -

  • Prefer complete plant be submitted
  • Staff could review for certification less than the complete plant provided the following were met:

(1) Sufficient infomation is included in the application to allow completion of a PRA and safety analysis.

(2) Compliance with interface requirements is verifiable through inspection, testing, previous experience or analysis. Reliability verification must be based on previous experience or testing.

(3) Certified portion of the design should include all systems, structures and components important to safety.

(4) Representative design for the non-certified portion of the plant should be provided as an example of how inter-face criteria can be met.

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Advanced Reactor Designs Minutes February 4, 1987 Issue #2 - Level of design detail to be certified -

  • Prefer final design information
  • Staff could review for certification less than final design information provided the following were met:

(1) The level of design detail provided is sufficient to allow development and review of a PRA and safety analy-sis.

(2) The level of design detail provided is sufficient to support procurement, construction and operation of systems, structures and components that meet the perfor-mance and reliability characteristics assumed in the PRA and safety analysis.

(3) A representative design for those portions of the plant not finalized is submitted as an example,of how the final design will look to aid in the review of the PRA and safety analysis.

Issue #3 - Prototype Testing -

  • A prototype plant should be built and tested prior to design certification by NRC unless the following can be demonstrated:

(1) The performance of each safety feature of the plant has been demonstrated via previous experience or full scale testing.

(2) Sufficient performance data exists on each safety feature of the plant to validate safety analysis analytical tools over a full range of operating and accident conditions, including plant lifetime.

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Advanced Reactor Designs Minutes February 4, 1987 (3) System interaction effects among the plant's safety features have been properly accounted for.

Issue #4 - Design Certification Options -

  • A design certification with plant module size / options is acceptable provided that these options are described in the application, including: (1) variations in or sharing of common' systems,(2)variationsininterfacerequirements,and (3) variations in system interaction.
  • The PRA and safety analysis should assess each of the options, including any restrictions during the construction and startup phase, to ensure safe operation of those modules already on line.

Issue #5 - Manufacturing License (ML) -

  • Extent of proposed shop fabrication appears to be equivalent to fabrication of major components, not complete plant.
  • ML is not required unless an essentially ready to operate plant is shop fabricated.

Mr. King stated that the ACRS review and feedback on the issues and proposed staff positions associated with advanced reactor stand-ardization are being sought at this time to allow consideration of ACRS comments prior to presenting a recommendation to the Comis-sion. Only verbal feedback is desired. Timing of a recommendation to the Comission is currently under review.

0-4 Advanced Reactor Designs Minutes February 4,1987 VII. As a ' result of the Subcommittee's discussion, the Subcommittee members raised some concerns regarding the following:

  • Dr. Mark expressed some concern regarding the use and appli-cability of the same General Design Criteria (GDC) for LWRs on these non-LWRs advanced designs. He advised the Staff not to use the same philosophy as apparently in the case of Fort St.

Vrain.

  • Dr. Siess is concerned regarding-the standardization versus the certification issue. He indicated that standardization is basically a business decision that relates to marketing and economics. Certification is not an essential feature of ~

standardization. Theoretically, a standard design could be developed without the intent to have it certified. Certifica-tion is one option offered by NRC.

  • Some concern has been raised regarding the extent and depth of certification especially for the MHTGR and PRISM designs.
  • Some concern has been raised regarding the need for a proto-type demonstration for the MHTGR design.
  • Mr. Ebersole expressed some concern regarding the consid-eration of the steam generator as a non-safety grade system.
  • Some concern has been raised regarding certification could limit any design changes that could be made.
  • Dr. Siess mentioned that for these new designs and from DOE's and its contractor's presentations, there is a confusion 1

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Advanced Reactor Designs Minutes February 4, 1987 regarding the applicability of important to safety and safety-related.

  • Dr. Shewmon likes to know if the PRA will be used to determine what is important to safety. The Staff is currently reviewing the PRA to determine if that is the case.
  • Dr. Carbon is concerned regarding the definition and meaning of " interface requirements" for the new designs.
  • Dr. Carbon indicated that the NRC Staff should encourage the technology of shop fabrication and installation of core assemblies in the factory, and consequently, there is no need to require manufacturing license (ML).
  • Dr. Shewmon questioned the availability of high-temperature fuel codes for the new advanced designs. RI could demonstrate the availability of some codes, but GE and GA Technologies could not. The NRC Staff indicated they had difficulties dealing with the Clinch River reactor fuel codes.

FUTURE ACTIONS:

The Subcomittee Chainnan will brief the full Comittee regarding Subcorr11ttee activities at the February 1987(322nd)ACRSmeeting. The NRC Staff will also present a brief overview of a draft Comission Paper on Standardization.

NOTE: Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room, 1717 H Street, NW, Washington, DC, or can be purchased from ACE-Federal Reporters, 444 North Capitol Street, Washington, DC 20001 (202) 347-3700.

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