ML20024C062

Testimony of Tl King Re ASLB Question 13 on Fuel Sys Fallback Positions.Lists Possible Impacts on Crbr Programmatic Objectives from Implementing NRC Positions. Prof Qualifications Encl

ML20024C062
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Site:	Clinch River
Issue date:	07/08/1983
From:	King T Office of Nuclear Reactor Regulation
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NUDOCS 8307120220
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O UNITED STATES OF AMERICA NUCLEAR REGULATORY C0tEISSION BEFORE THE ATOMIC SAFETY LICENSING BOARD In the Matter of UNITED STATES DEPARTMENT OF ENERGY Docket No. 50-537 PROJECT MANAGEMENT CORPORATION TENNESS2E VALLEY AUTHORITY (Clinch River Breeder Reactor Plant) )

NRC STAFF TESTIMONY OF THOMAS L. KING ON BOARD QUESTION 13, CONCERNING FUEL SYSTEM FALLBACK POSITIONS Q1. Mr. King, please state your name, by whom are you employed, and the nature of your responsibilities regarding the Clinch River Breeder Reactor ("CRBR")?

A1. My name is Thomas L. King.

I am employed by the U.S. Nuclear Regu-1 l

latory Commission as Chief of the Technical Review Branch, Clinch River Breeder Reactor Program Office, in the Office of Nuclear Reactor Regulation.

I am responsible for direction of the Technical Review Branch's review of the fast sodium-cooled-related aspects of the CRBR safety review.

Q2. Have you prepared a statement of professicnal qualifications?

l A2. Yes. A copy of my statement is attached to this testimony.

Q3. What is the purpose of your testimony?

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A3. My testimony addresses the concern raised by the Atomic Safety and LicensingBoard(" Board")inBoardQuestion13,whichstatesas follows:

With respect to the fuel system, the Staff has identified certain operational fallback positions potentially available to mitigate unresolved problems (NUREG-0968, Vol.1, p. 4-47, 48). The Staff is requested to discuss briefly the extent if any to which invoking such operationel fa11 backs might compromise the achievement of CRBR programmatic objectives.

Q4. What are the CRBR Programmatic Objectives?

A4. The Applicants' programmatic objectives are documented in the LMFBR Final Environmental Impact Statement Supplement, LMFBR Program (DOE /EIS-0085-FS, May 1982, page 57) as follows:

o To demonstrate the technical performance, reliability, maintainability, safety, environmental acceptability, and economic feasibility of an LMFBR central station electric power plant in a utility environment.

o To confirm the value of chis concept for conserving important non-renewable natural resources.

Similarly, the programmatic objectives are described in Applicants' CRBR Environmental Report, Sections 1.2 and 1.3 (Amendment XIII, April 1982) as follows:

o Technical performance - demonstrate all necessary LMFBR technology.

o Reliability - 75% station factor during demonstration period.

o Maintainability - minimum downtime.

o Safety - demonstrate LMFBR safety.

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o Environmental acceptability - demonstrate minimal environmental impacts of LMFBRs.

o Etonomic feasibility - provide data for use in estimating costs of commercial-size LMFBRs.

Q5. What are the Staff's fuel system fallbaskLpositidns?_

AS. The Staff's fuel system' fa'11back positi_ons consist of restrictions on CRBR operation which can be imposed to resolve the Staff's concerns regarding the fuel system design basis, limits and methodology if future analytical and experimental data do not s

substantiate the Applicants' proposed design.,Specifically, the fallback positions are:

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1) reductiori'of goal expdsure- (burnup);

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3) lower operating temperature; and i

4) adjustment of plant protection system 5 trio. points.

These fallback positions are documented on pages 4-47 and 4-48 of the CRBR SER, NUREG-0968'.'

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y A6. The CRBR prograinnatic objectives listed above are, for the most L. -

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part, general in' nature, and any, impacts must be discussed in a qualitative sensec Quantitative impacts can be discussed, however, -

as to some of the more important CR3R design'pa'rameters related to s

fuel performance, i.e., breeding ratth andid'oubling time.

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Listed below are the possible impacts on the CRBR programmatic objectives which might result from implementing the Staff's fallback positions:

1.

Technical Performance: Fuel system performance would still be demonstrated but not to a performance level desired by the Applicants.

2.

Reliability: The 75% station factor objective could be impacted if reduced burnup, power level or operating temperature were imposed on CRBR, causing shorter cycle lengths (and thus addi-tional downtime for refueling) and/or lower power output (thus not allowing CRBR to produce electricity at full capacity).

Also, if reduced trip points caused additional spurious plant scrams, the station factor objective would be unfavorably impacted.

3.

Maintainability:

In one regard, the impact could be favorable, by providing less of a demand for extended operation and more plant downtime for maintenance; in another regard, the impact could be unfavorable, by requiring some equipment tsuch as the i

refueling equipment) to be used more often, thus requiring more l

maintenance.

4.

Safety: Reducing power level, operating temperature or trip i

l points would have a favorable impact on safety by providing l

more margin between plant operating conditions and design conditions.

If the reduced burnup fallback were imposed in

. time to affect fabrication, the enrichment of the fuel would not have to be as high thus reducing excess reactivity and

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providing more U-238 in the core for Doppler feedback.

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Environmental acceptability: No impact.

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Economic feasibility: All of the fallback positions have the potential for impacting LMFBR economic feasibility unfavorably if future relief from these fallback positions cannot be obtained.

Q7. Please describe the possible impacts on the CRBR design parameters related to fuel performance which might result from imposition of the Staff's fallback positions?

A7. The CRBR design parameters assessed for impact were breeding ratio

("BR") and doubling time ("DT"). The Applicants' design values for these parameters for cycle 1 are BR = 1.26 and DT = 33 years.

1.

Reduction in goal exposure: A reduction in goal exposure will increase the average BR. This is because the BR decreases over a cycle (due to the removal of U-238 by fast fission and conversion to Pu-239), and shortening the cycle will remove that portion of the cycle where the BR is lowest, thus increasing the average BR. This increase in BR will be small, however, since the BR changes only slightly over a cycle (for example, from beginning of cycle 1 to end of cycle 2, the BR goes from 1.27 to 1.23).

The effect on doubling time of a reduction in goal exposures is to increase slightly the DT. This is due to the reduced plant factor caused by more frequent refueling outages and the additional reprocessing losses due to more fuel going through e.

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the reprocessing line. For example, the increase in DT for a 10% reduction in goal burnup would be 1 year (from a 33 year DT to34yearDT).

2.

Reduction in peak power: A reduction in peak power would have a negligible affect on BR but would increase the DT due to a longer cycle length (assuming the goal burnup is unchanged).

For example, a 10% longer cycle would cause approximately a 10% increase in DT.

3.

Lower operating temperature: Negligible change in BR or DT.

4.

Reduced trip points: Negligible change in BR or DT.

Q8.

Is it likely that such fa11 backs will have to be implemented? If so, what is expected as to the magnitude of reductions in burnup, peak power, operating temperature and trip points?

A8. The Staff's judgement is that it is unlikely that any of the fall-back positions discussed above will have to be implemented. This judgement is based upon the fact that the Staff's concerns are largely with the analytical methods and assumptions used in the fuel design, and upon the fact that the Applicants have committed to address these concerns with experimental and analytical programs.

In addition, FFTF has reached a peak burnup of 60,000 MWD /MT in its driver fuel under temperatures and peak power conditions very close to that for CRBR, without a single detectable failure. Also, many CRBR prototype fuel pins have been irradiated in EBR-II to peak burnups of 80,000 MWD /MT or beyond, under prototypic peak power conditions. Thus there is considerable experimental evidence that

the CRBR fuel is likely to meet its design goal of 80,000 MWD /MT peak burnup at full power conditions. Based upon the FFTF experience, 60,000 MWD /MT burnup at CRBR power and temperature cor:ditions appear at this time to be the minimum achievable.

Additional data at higher burnups are expected in the near future.

Reductions in trip points, if required, would likely be in the range of a few percent and, based upon FFTF experience, would net cause any impact on normal plant operation.

Q9.

Is it anticipated that the Staff's fallback positions will compromise the achievement of the CRBR programmatic objectives?

A9. No. As stated by the Applicants in a letter from J. R. Longenecker (DOE) to J. N. Grace (NRC), dated June 17,1983 (attached hereto as "BoardQuestion13 Attachment 1"),evenintheeventthatthe fallback positions are implemented for the first core loading, it is unlikely that CRBR programmatic objectives will be compromised.

This position is based upon the fact that imposition of fallback positions at the OL stage does not necessarily mean that these restrictions will stay in place for the life of the plant.

Future design changes and experimental data can be used by the Applicants to demonstrate that their design goals can be achieved or exceeded.

If the Staff determines that these design changes or additional data adequately resolve the Staff's concerns, the restrictions on opera-tion may be removed.

Thomas L. King PROFESSIONAL QUALIFICATIONS I am presently Chief, Technical Review Branch in the CRBR Program Office, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Comission.

In this capacity, I am responsible for the direction of the Branch's Review of those aspects of CRBRP related to a fast, sodium cooled reactor. This includes direction of the Branch's review of CRBRP sodium systems, fuel handling systems, CDA analysis, support systems, reliability program, safety criteria and analysis.

I received a Bachelor of Science degree in Mechanical Engineering from Drexel University.

I also received a Master of Science degree in Mechanical Engineering from Stanford University.

I have over fourteen years of professional experience in the nuclear field, whileIworkedfortheDepartmentofEnergy(DOE),Iheldvariouspositions in the Division of Reactor Research and Technology. These included positions as a Reactor and Nuclear Engineer in the Core Design Branch, the Liquid Metal Systems Branch, and the Components Branch where I worked on the FFTF Project, the EBR-2 project and Facilities at the Engineering Technology Center in Santa Susana, California.

In 1975 I was assigned to the DOE FFTF Project Office in Richland, Washington where I held positions as a Reactor l

Engineer in the Operational & Experimental Safety Division and Branch Chief for FFTF Engineering until April 1982 at which time I joined the NRC as a l

Reactor Engineer.

List of Publications 1)

"FFTF Reactor Characterization Program" T. L. King (DOE) & J. Rawlins (HEDL) l ANS invited paper - 1981 Winter Meeting - San Francisco 2)

" Reactor and Plant Performance During FFTF Nuclear Startup" T. L. King & C. E. Moore - DOE Ans Topical Meeting - September 1981 - Newport, RI (Technical Basis for Nuclear Fuel Cycle Policy)

BOARD QUESTION 13, ATTACHENT 1 4

Department of Energy Washington, D.C. 20545 JUN 171983 Docket No. 50-537 HQ:S:83:256 Dr. J. Nelson Grace. Ofrector CRBR Program Office Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.

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SUMMARY

OF JUNE 10, 1983 MEETING ON PROGRAMMATIC OBJECTIVES On June 10, 1983, the project met with the Nuclear Regulatory Commission (NRC) to discuss the fa11 backs identified in Chapter 4 of the Safety Evaluation Report and their impact, if any, on the Clinch River Breeder Reactor Plant (CRBRP) progransnatic objectives. The attendees are identified in Enclosure 1 and the viewgraphs are in Enclosure 2.

In summary, the programmatic objectives of CRBRP are to demonstrate the technical performance, safety, reliability, maintainability, environmental acceptability, and economic feasibility of a liquid metal fast breeder CRBRP is a natural progression reactor operating in a utility environment.

from smaller plants, in which lessons were learned, to larger plants and will allow for the extrapolation of results on various systems and com As such, one of the purposes of a ponents to larger 1.MFBR plants.

demonstration plant is to identify problem areas that are not anticipated If the from existing experimental data or from existing operating plants problem areas are identified prior to or during CRBRP operation, design t

modifications can be made in the plant and shown to be effective prior to entering into full-scale deployment of the reactor concept and plant design.

It is not anticipated that the potential fallback positions identified by Programs are in place to resolve the concerns of NRC will be necessary.

NRC and to quantify the potential effects if they occur prior to CRBRP In the unlikely case that these programs do result in the operation.

necessity to implement any of the fallback positions, the fa11 backs necessary for the initial fuel loading will not result in compromises to the achievement of CRBRP programmatic objectives. This is because the lessons learned in the initial operation of CRBRP can easily be factored into reload designs and will create the technology data base to be used i

for the follow-on plant designs.

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Further, the success of the CRBRP demonstration plant will be evaluated not only on the basis of fuel performance, but also on the bases of technology developed 'and demonstrated for overall plant and system performance, of which the fuel is only a small part.

More specific information on the impact of fuel fallback positions on first core breeding and doubling time characteristics is in Enclosure 3.

If you have any questions, please call Wayne Pasko at the CRBRP Project Office (FTS 626-6096).

Sincerely, i

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Demonstration Projects Office of Nuclear Energy 3 Enclosures cc: Service List Standard Distribution Licensing Distribution o

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4 ATTENDEES

5. Additon, WLLCO K. Peterman, CRBRP PO W. Pasko, CRBRP PO A. Schwallie, W-AEsd R. Stark, NRC Lenny Rib, LNR G. Sherwood, DOE B. Neuhold DOE D. Ujifusa, DOE T. King, NRC e

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EFFECT OF FALLDACKS O!! CRBRP FUEL SYSTEM PROGRAFFATIC OBJECTIVES e

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REAS0;;AELE BASIS TO EXPECT FUEL DESIGr! WILL #i:0VE SUCCESSFL'L BASED Oft:

0 IRRADI ATED ROD FAILURE THRESliOLD Ut! DER LCSS-OF-FLOW CO;DIT101:5 TO A!! EX?OSURE OF 50,000 Mild /MT BY A MARGIfl 0F AT LEAST 200*F (BASED 0:: 1600*F GUIDELIl!E) o THER: AL C0r!DITIOil 0F FUEL AliD CLADDING AT FAILURE THRESHOLDS FOR IRRADI ATED RODS (TREAT TESTS) A!!E FAR AECVE CRBRP DBA BASIS EVE!!T PEAK THER:4AL CONDITIOi:S C

CL.".LDI!;G FAILURES F.OR EBR-II TEST RODS WERE VERY S?!.RSE; ATYPICAL FACTORS C0!!TRIBUTED TO I40ST 0F THESE FAILURES (I.E.,

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CRBR? PROGRA!iiMTIC OBJECTIVES 1.

FINAL ENvlRor: met;TAL lliPACT STATE!4E!!T SUPPLEMEitT,.U(FBR PaocRAM (DOE /EIS-0085-FS, HAY 1982, PAGE 57):

o To DEMONSTRATE IHE IEClittICAL PERFoRf4A!!CE, RELI ABILITY, IIAI!;TAINALILITY, SAFETY, ENVIRONMENTAL ACCEPTABILITY, AND ECONOMIC FEASIBILITY OF AN UiFBR CEf: TRAL STATION ELECTRIC PoWERPLAllT I!! A UTILITY ENVIP,01:MENTJ

'O To CO!; FIRM IHE VALUE OF IHIS' CCNCEPT fbR C0tGERVIriG lt4 PORTA!!T I!Ot! RENEWABLE NATURAL RESOURCES.

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E::vlaa:. MENTAL REPORT, CRBRP, SECTIONS 1.2 Ara 1.3 (hiENDMENT XUI APalt 1932):

o TECHNICAL PERFORMA!!CE - DEMONSTRATE ALL NECESSARY Ui BR TECH::0*_0GY.

76 RELIABILITY -.74% STATIoM FACTOR DuRIr:G DEMONSTRATION l

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o 'I'IAlt:TAINABILITY - ISINIMUM DONNTIME.

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SAFETY - DEMONSTRATE UiFBR SAFETY.

o ENVIRoi, MENTAL ACCEPTABILITY - DEf40t: STRATE Illillt4AL ENVIRc:: MENTAL IMPACTS OF U;FBRS.

o Ec c:rr.It FEASIBILITY - PR0 vine DATA FOR USE IN ESTIMATING COSTS OF CoMMERCI AL-SIZE UicERS.

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Irract of Fuel Fallback Positions on First Core Breedina and Doublina Time Characteristics 1)

Reduction in Goal Burnuo It is assumed that the decision to reduce the goal burnup for the CRBRP first core fuel is made after the fuel has been fabricated so there is no opportunity to fine-tune the fuel enrichment to compensate for the resultant shorter burnup interval.

The reference CRBRP first core breeding ratio, with low-240 grade Plutonium fuel, decreases from a value of 1.27 at the start of cycle 1 to approximately 1.23 at the end of cycle 2 (328 ef pd and 80 MW6/kg burnup) and averages 1.25.

If the goal burnup is reduced 10% by truncating the cycle length, the cycle-average breeding ratio, which is the ratio of the production rate of fissile fuel divided by the destruction rate of fissile fuel, increases slightly (to 1.252) due to dropping off a fraction of the cycle where the breeding rate is lowest.

The excess fissile mass gain (fissile produced - fissile destroyed) would decrease in For the CRBRP proportion to the reduction in cycle length.

first core, a 10% reduction in goal burnup, and a corre-sponding 10% reduction in cycle lenf'h, would result in a loss of approximately 7 kg from the total fissile gain of 80 kg in cycles 1 and 2.

The doubling time is fundamentally a measure of the growth rate of the fuelisystem (ratio of the fissile mass investment to the net fissile mass gain per If the reduction in goal burnup persists into the year).

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equilibrium cycles, the fissile mass gain per cycle is reduced, but, because of the shorter cycle length, th,e average number of cycles per year increases in near1r a compensating fashion so that the doubling time only increases slightly (from 33 to 34 years for a 10% reduction in goal This net increase in doubling time is, in fact, burnup).

attributable to a slight increase in fissile material losses because the fuel must be reprocessed more frequently at reduced burnup levels over the plant lifetime.

2)

Peduction in Oceratina Power Level If the plant power level is derated, the cycle length (in calendar days) can either be. increased to maintain the eff ective full power days of operation and the goal burnup, or the cycle length (in calendar days) can be held constant In the first which results in a reduction in goal burnup.

case, the average breeding ratio is essentially the same i

except for a small reduction associated with a decrease in 238 The l

temperature-dependent resonance absorption in U total fissile mass gain over the cycle is the same, but the doubling time is longer because each cycle is longer at the reduced power level.

For example, a 10% reduction in reactor power level requires a 10% longer cycle to achieve goal burnup and this results in a 10% longer doubling time (approximately 36 years compared to the reference 33 year On the other hand, if the cycle length is held value).

constant, the reduction in reactor power level results in a In this case, the corresponding reduction in goal burnup.

total fissile gain during the cycle is reduced, and the For example, the same 104 reduction doubling time is longer.

in reactor power level at constant cycle length results in a 10% reduction in fissile gain and a slightly longer ( 12%)

doubling time (the effect is compounded somewhat because of the somewhat larger proportion of reprocessing losses compared to the gross fissile gain).

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Reduction in Fuel Temocrature or Trin Level Settinos Reducing the core inlet or outlet temperature affects a This fuel similar reduction in fuel pellet temperature.

temperature reduction has essentially no impact on the core 238 resonance breeding ratio (except for the reduction in U absorption which is negligible) or doubling time.

Similarly, a reduction in transient trip level settings has no impact on the steady-state core breeding and doubling time characteris-tic so long as the increased probability of inadvertent reactor trips does not lower the plant capacity factor.

In summary,. invoking a f allback reduction in CRBRP core power and/or burnup performance results in a very small increase in breeding ratio and a somewhat' longer doubling time.

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