ML20246N988
| ML20246N988 | |
| Person / Time | |
|---|---|
| Issue date: | 05/02/1989 |
| From: | Zech L NRC COMMISSION (OCM) |
| To: | Sharp P HOUSE OF REP., ENERGY & COMMERCE |
| Shared Package | |
| ML20246D630 | List: |
| References | |
| NUDOCS 8905220053 | |
| Download: ML20246N988 (22) | |
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- . (o,, . UNITED STATES 'fp/d f f y - } ) ~, ( g NUCLEAR REGULATORY COMMISSION q g WASHINGTON, D. C. 20555 f ,. q j S
.....# May 2., 1989 CHAIRMAN l
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The Honorable Philip R. Sharp, Chairman ;
Subconnittee on Energy and Power !
.Comittee on Energy and Comerce United States House of Representatives Washington, D. C. 20515
Dear Mr. Chairman:
In response to your letter of April 7,1989, to Mr. Thomas L. . King of the NRC staff, please find our responses to Congressman Markey's ouestions enclosed.
Sincerely, L ,
Lando W. Z , Jr
Enclosure:
Responses to Questions cc: Representative Carlos J. Moorhead S
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i Response to Ouestions from Congressman Markey - Follocuo
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from March 15, 1989 Hearina on Advanced Reactors 1
I QUESTION 1. In your prepared statement you say that (quote) "The MHTGR has the potential to achieve a level of safety at least j equivalent to that of current generation LWRs (light water reactors) and, in some areas, has the potential to provide enhanced safety beyond that of current generations LWRs."
A) Why should this nation commit billions of dollars to ]
developing MHTGR if best NRC can tell us is that it has the " potential" to be as safe as the existing generation aiid only has the " potential" to-be safer in certain areas?
ANSWER The use of the word " potential" in the testimony in describing the safety of the MHTGR chould not be taken to mean that the design has little promise to actually achieve enhanced safety in many areas. The word was chosen to reflect _the current status of tne design, its supporting research and developneirt, and the NRC review.
Dur review of the MHTGR was conducted at the conceptual (preapplication) design stage with the purpose of providing early guidance on the
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QUESTIOli 1. (Continued) acceptability of the design. As such, our review was not directed toward approving the design or making a final safety determination, but rather on identifying the major design and research and development' related items
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which would need to be addressed if such a design is to be licensed, I j
Completien of the design and its supporting research and development, )
coupled with a formal NRC licensing review, would be required before we could make any final determinations on the safety of the MHTGR.
Accordingly, we used the word " potential" to characterize the results of I
our evaluation at the conceptual design stage while recognizing that a '
significant amount of work remains to be done before a final determination can be made.
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QUESTION 1. (Continued) I B) In what areas does NRC believe MHTGR has the least potential to be as safe as existing technologies?
ANSWER The results of the staff's review to date on the MHTGR can be' characterized as falling into two basic areas: (1) those which show the potential for enhanced safety beyond current generation reactors and (2) those which show the potential for equivalent safety. The major items in each of these categories are as follows:
(1) Enhanced Safety:
plant response to severe challenges plant dependence on human action
- plant response time under transient conditions plant dependence on electric power and active systems (2) Equivalent Safety:
plant response to anticipated operational occurrences However, many specific design and research and development items remain to be completed before final judgment on the . safety of the MHTGR can be made.
These items are discussed in cur draft safety evaluation report for the MHTGR(NUREG-1338).
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b-W QUESTION 2 Isn't it true' that the Fort St. Vrain Gas-cooled reactor'in Colorado has had a variety of malfunctions since its initial start up, and that its utility cwner recently:
announced it would abaridon..the plant for comercial operation in 1990. What is NRC's assessment of the safety and reliability of the Fort St. Vrain Gas-cooled reactor,'
compared to~.the current generation of light water reactorst What does this say about the advisability of relying on this:
technology to meet our national security.needs?
ANSWER It is true that Fort St. Vrain has had a variety of operational. problems over its service life which have affected plant availability and that Public Service Company of Colorado (owner.and operator of Fort St. Vrain) notified us in '
December '1988 of early tennination of Fort St. Vrain operations. Plant <
availability has generally been lower than LWR's of the same vintage ,
I which, to a large degree, has been oue to leakage problems with the' helium 1 circulators. The correction of the problem is of primary concern to the designers of the new MHTGR's.
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'In our view, the safety of Fort St. Vrain is comparable to that of existing .I light water reactors. However, there are two areas where we believe Fort 1
St. Vrain has . enhanced safety characteristics beyond existing light water .l reactors: ,
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OUESTION 2. '(Continued) 1. .
-(a) ~ lower radiological exposure rates for operating personnel,
.and (b) longer response times under. core heatup accidents.
The NRC has not been involved in'any assessments regarding the use of this
' technology to meet national security needs (i e. . as a production reactor) and, therefore, cannot coment on this -issue.
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OtJESTION 3. .Does the NRC believe that industry should pick up the expense of developing advanced reactor technologies?:
ANSWER The NRC 's responsibility does not include developing advanced reactor technologies. Therefore it is not within our purview to determine who (industry, government, or combination thereof) should fund such advanced developments.
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D OUESTION 4 .Your prepareo statement also reports that DOE's version of the MHTGR is going to be somewhat different from a ccmmercial MHTGR, in that it "would employ a containment-structure not proposed to the NRC for the comercial version."
A) Why is the DOE proposing a different containment structure for its MHTGR7
-ANSWER-The Commission has requesteo'the DOE to explain their rationale for proposing a containment structure for the new production reactor (NPR) version of the MHTGR but not for the commercial version. DOE's response is expected in June of this year.
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s QUESTION A. (Continued) B) How does this proposed containment structure differ from those being considered for the comercial version of MHTGR? Is it more safe or less safe?
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The comercial version of the MHTGR, as proposed to NRC, has no containment structure. The non-power reactor (NPR) version of the MHTGR, as we under-stand it, has a containment structure, although its design and supporting design basis have not been reviewed by NRC. We cannot coment on the comparative safety of the two concepts since we have not reviewed the design of the NPR-MHTGR.
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.00ESTION 4. (Continued) C) Your statement says that NRC needs additional information to resolve its concerns about-this matter. What are NRC's " concerns"?
ANSWER We need to understand DOE's rationale for not including a containment structure on the commercial MHTGR concept while a containment structure was proposed for the NPR-MHTGR concept. Specifically, we are interested in knowing the technical and policy considerations which led DOE to these differing posif. ions on two apparently similar designs in order to ensure that we are aware of all relevant safety considerations.
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00EST10N 5. Your prepared statement mentions that NRC and DOE have had seveal communications on the containment issue, including an August 17, 1988 letter from Mr. Stello to DOE, a September 1988 DOE response, and "further communications" with DOE. Plt:ase provide copies of all of these documents.
ANSWEfg Copies of the August 17, 1988 and September 16, 1988 lettert are enclosed along with copies of October 3,1988, October 25, 1988, and huvember 14, 1988 internal mem6randa documenting our further communications with DOE on the enntainment issue.
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QUESTION 6. .Your statement also mentions that the ACRS reported to the Comission in an October 13, 1988 letter on its findings regarding safety issues for MHTGR, and that ACRS also provided a number of coments on the design. Could ycu also provide copies of all of these documents?
r-ANSWER A copy of the October 13, 1988 ACRS letter is enclor,ed. This letter
. includes ACRS coments on the MHTGR conceptual design. Also enclosed is a copy of a July 20, 1988 ACRS letter, which addresses certain key licensing issues comon to both the MHTGR design and the liquid metal reactor conceptual designs under review by the Comission.
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i-OVESTION 7.- You indicatea that preliminary. design approval for NHTGR e
would be completed by 1992, based on projected schedules provided by DOE. Has NRC conducted any detailed examination of these projected schedules? If so, do you think they are realistic, or do you believe PDA may be delayed?
ANSWER NRC has not conducted any detailed examination of the DOE projected scheoules for the VHTGR. The cates quoted are those developed by DOE.
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l QUESTION 8. When do you think final design approval for MHTGR will take place?
I' ANSWER This question cannot be answered at this time. The answer is highly dependent upon factors beyond NRC control and responsibility, such as DOE and private sector support and funding for t'he MHTGR and completion of both design and research and development activities for the MHTGR.
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QUESTION 9. Your statement mentions two ACRS letter reports on safety of liquid metal reactor designs that were issued on November 22, 1988 and January 19, 1989. Could you provide-copies of those docrments?
ANSWER Copies of the requested letter reports are enclosed.
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OVESTION 10. Mr. ' King, on page 4 of your prepared statement,'you .
indicate that "the evolutionary LWRs'are expected to achieve an enhanced level of safety over existing LWRs by.
incorporating evolutionary design improvements'(for example, p . implementation of lessons learned from many years of operating experience), addressing severe accident' issues at the design stage, and standardization. Can some of the " evolutionary-design improvements" you're talking about be backfitted .
into existing reactors to improve: their safety?
A) .If your answer is yes, is the NRC asking the nuclear industry to implement these " evolutionary design improvements"? If some of these technologies can be backfitted into existing reactors, why does it take a
' DOE program to underwrite the cost of developing 90 percent of these advanced designs to' implement these-safety improvements?
B) If your answer is no, does this mean that existing reactors are not safe enough because these new design improvements can't be incorporated into them?
ANSWER L
Some of the evolutionary design improvements have been backfitted into
- existing reactors to improve their safety. This has occurred and will continue to occur through several mechanisms, as summarized below:
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i OUESTION 10. (Continued) )
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I 1)- As design issues are identified through operating experience, I research and development, or other mechanisms, such as probabi-listic risk analysis, they are evaluated for their safeu significance and, if warranted, backfitted onto existing designs using the Commission's rules and regulatory authority provided by the Atomic Energy Act. Additional rulemaking, bulletins, orders, and generic letters are some of the ways by which this upgrading of safety is accomplished.
- 2) Currently, severe accident issues for existing plants are being evaluated, and decisions are being and have been made regarding backfitting design and operational or administrative improve-ments. The following specific initiatives are currently underway:
t-a containment performance improvement program looking at prospective ways to enhance the ability of existing containment designs to withstand the effects of severe accidents an accident management program looking at ways for plants to enhance the diagnosis, prevention, and control of such unlikely accidents I
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.7-QUESTION 10. (Continued) an individual plant examination program looking at each existing design to determine whether particular vulnera-bilities to severe accidents exist and whether any corrective actions are needed.
It should be noted, however, that the backfitting process in-volves enhancement of existing designs beyond what is required for adequate protection of the public health and safety and that the backfitting process includes an evaluation of additional cost versus potential safety benefit. Backfitting may not be justi-fied in some cases for existing plants because of the high cost of modifying plants compared to the relatively small improvement to safety that could be achieved. However, for new designs, the front end cost of making changes may be very small, thereby making these changes desirable. Thus, the staff expects these new designs to contain uany safety enhancements (that mignt not be justified for backfitting on existing plants) that will make the new designs incrementally safer than existing LWR's.
The Comission is not in a position to comment on DOE funding of evolutionary LWR designs since developmental funding arrangercents are not within the Comission's area of responsibility.
Questions in this regard should be directed to DOE.
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CUESTION 11. How do you think the costs of the advanced reactor technologies you've been looking at will compare to the costs of the existing generation of reactors? Will they be more expensive, less expensive, or about the same?
ANSWER The NRC has not reviewed the costs associated with the development or deployment of.the advanceo reactor technologies.
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QUESTION 12.. I uncerstand that the new designs are generally smaller than the current generation--between 150 and 600 megawatts as opposed to 1200 megawatts. Are'these advanced reactors going to cost more per megawatt of electricity they produce than the current generation?
o ANSWER The NRC has not reviewed the power generation costs associated with the new' designs.
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advanced reactor area? Is there a Memorandum of Understanding outlining these roles and responsibilities?
If so, please provide a copy.
ANSWER NRC's role in the advanced reactor area is to independently evaluate the safety and licensability of those advanced reactor designs with potential comercial application that are presented for review at the conceptual l design stage. Ultimately, NRC will review for approval any formal applica-tions received for an advanced reactor design for a ctandard plant review, construction pennit, or operating license. This role is consistent with I
that provided for in NRC's authorizing legislation.
DOE's role in the advanced reactor area is broader than the NRC's and includes design and concept development. A complete sumary of specific 1
details on the extent of DOE's responsibilities should be obtained from DOE. There is no NRC/ DOE Nemorandum of Understanding specifically relating to the advanced reactor area.
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OUESTION 14 Please explain what mechanisms exist to prevent duplication of effort between DOE and NRC in the advanced reactor area.
ANSWER DOE has requested NRC to perform a safety evaluation on the licensability of certain advanced reactor concepts that are under development. DOE has provided documentation and information necessary for the review and has kept NRC infomed of progress. There is no duplication of effort by virtue of the two separate' roles of NRC and DOE; namely NRC's role to independently evaluate the safety of the design and DOE's role to support concept development.
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