ML20076J095

Summarizes Programmatic Objectives 830610 Meeting Re Fallbacks Identified in Chapter 4 of SER & Impact on Crbr Project.Viewgraphs & Supporting Documentation Encl

ML20076J095
Person / Time
Site:	Clinch River
Issue date:	06/17/1983
From:	Longenecker J ENERGY, DEPT. OF
To:	Grace J Office of Nuclear Reactor Regulation
References
HQ:S:83:256, NUDOCS 8306200325
Download: ML20076J095 (17)

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9 Department of Energy Washington, D.C. 20545 JUN 171983 Docket No. 50-537 HQ:S:83:256 Dr. J. Nelson Grace, Director 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 fallbacks identified in Chapter 4 of the Safety Evaluation Report and their impact, if any, on the Clinch River Breeder Reactor Plant (CRBRP) programmatic 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

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reactor operating in a utility environment. CRBRP is a natural progression from smaller plants, in which lessons were learned, to larger plants and will allow for the extrapolation of results on various systems and com-ponents to larger LMFBR plants. As such, one of the purposes of a demonstration plant is to identify problem areas that are not anticipated from existing experimental data or from existing operating plants.

If the problem areas are identified prior to or during CRBRP operation, design

- 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 NRC will be necessary. Programs are in place to resolve the concerns of NRC and to quantify the potential effects if they occur prior to CRBRP operation.

In the unlikely case that these programs do result in the i

necessity to implement any of the fallback positions, the fallbacks I

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 for the follow-on plant designs.

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2 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,

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Director, Office of Breeder Demonstration Projects Office of Nuclear Energy 3 Enclosures cc: Service List Standard Distribution Licensing Distribution J

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ATTENDEES S. Additon, WLLC0 K. Peterman, CRBRP P0 W. Pasko, CRBRP P0 A. Schwallie W-AESD R. Stark, NRC Lenny Rib, LNR

-G. Sherwood DOE B. Neuhold, 00E D. Ujifusa, DOE T. King, NRC t

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@AESD EFFECT OF FALLDACKS Oli CRBRP FUEL SYSTEM PROGRAF.MATIC OBJECTIVES i

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(j5ESD NRC - SER IDEllTIFIED C0:1CEPJiS AliD FALLBACK POSITIO!1S I

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REASO::AI'LE BASIS TO EXPECT FUEL DESIGf! WILL. PROVE SUCCESSFL'L BASED ON:

o IRRADI ATED ROD FAILURE THRESil0LD Uf! DER LOSS-OF-FLOW CO;DITIO!!S TO All EXPOSURE OF 50,000 MiiD/MT BY A MARG!!10F AT LEAST 200*F (BASED ON 160TF GUIDELIllE) o THERMAL CONDIT10ii 0F FUEL AfiD CLADDII;G AT FAILURE THRESHOLDS FOR 1RRADI ATED RODS (TREAT TESTS) ARE FAR ABOVE CRBRP DBA BASIS EVEf?T PEAK THERMAL CONDITIOi:S e

CL.",DDitJG FAILURES F,0R EBR-Il TEST RODS WERE VERY SPARSEJ ATYPICAL FACTORS CoiTRIBUTED TO MOST OF THESE FAILURES (1.E., REC 0i!STITUTION) f l

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l CRBR? PROGRA!iMATIC OBJECTIVES 1.

FINAL ENVIRONMENTAL IMPACT STATEME!!T SUPPLEMENT,.UiFBR PR0 CRAM (DOE /EIS-0085-FS, IiAY 1982, PAGE 57):

0 TO DEMONSTRATE THE IECliNICAL PERFORMANCE, RELI ABILITY, liAINTAINALILITY, SAFETY, ENVIRONMENTAL ACCEPTABILITY, AND ECONOMIC FEASIBILITY OF AN U4FBR CEi! TRAL STATION ELECTRIC POWERPLAllT ltl A UTILITY ENVIRONMENT;

'O TO C0!:FIF.M THE VALUE OF THIS' CONCEPT FOR CONSERVING IMPORTANT I!ONRENEWABLE llATURAL RESOURCES.

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ENviaa:: MENTAL REPORT, CRBRP, SECTIONS 1.2 AND 1.3 (h4ENDMENT X!il APRIL 1982):

o TECHNICAL PERFORMAi!CE - DEMONSTRATE ALL iiECESSARY UiFBR TECHNOLOGY.

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RELIABILITY

.7M STATION FACTOR DuRING DEMONSTRATION l

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PERIOD, O

I'IAINTAINABILITY - MINIMUM DOWNTIME.

O SAFETY - DEM0!1 STRATE UiFBR SAFETY.

O ENVIROI MENTAL ACCEPTABILITY - DEM0tlSTRATE MINIMAL I

ENVIRONMENTAL IMPACTS OF LliFBRS.

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Ec aM!t FEASIBILITY - PR0vlos DATA FOR USE 1N i

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ESTIMATiNo COSTS OF COMMERCI AL-SIZE U'IFBRS.

Impact of Fuel Fallback Positions on First Core Breedina and Doubling Time Characteristics 1)

Reduction in Goal Burnup Jt 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 mwd /kg burnup) and averages 1.25.

i 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 proportion to the reduction in cycle length.

For the CRBRP first core, a 10% reduction in goal bornup, and a corre-sponding 10% reduction in cycle length, 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 year).

If the reduction in goal burnup persists into the l..

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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 nearly a compensating f ashion so that the doubling time only increases l

slightly (from 33 to 34 years for a 10% reduction in goal burnup).

This net increase in doubling time is, in fact, 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.

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Reduction in Operatina 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 which results in a reduction in goal burnup.

In the first case, the average breeding ratio is essentially the same except for a small reduction associated with a decrease in 236 The 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).

the reduction in reactor power level results in a

constant, In this case, the corresponding reduction in goal burnup.

total fissile gain during the cycle is reduced, and the doubling time is longer.

For example, the same 10% reduction in reactor power level at constant cycle length results in a i

10% reduction in fissile gain and a slightly longer (~12%)

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

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3)

Reduction in Fuel Temperature or Trio Level Settinas 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 breeding ratio (except for the reduction in U238 resonance 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.