ML19345F670
| ML19345F670 | |
| Person / Time | |
|---|---|
| Site: | University of Michigan |
| Issue date: | 02/10/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19345F668 | List: |
| References | |
| NUDOCS 8102190005 | |
| Download: ML19345F670 (4) | |
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UNITED STATES
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,i NUCLEAR REGULATORY COMMISSION j. i, f ! i psmNGTON. D. C. 20555
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,y SAFETY EVALUATICN REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 27 TO FACILITY OPERATING LICENSE NO. R-28 THE UNIVERSITY CF MICHIGAN (UM) 00CXET NO. 50-2 INTRODUCTION In the national prooram to mitigate unauthorized fuel diversions by reducing the enrichment of U-235 in nuclear fuels to below 20%, the Department of Energy has mounted an extensive Low Enrichment Uranium (LEU) fuels development and safety program. Argonne National Laboratories is providing testing and development data on LEU fuels and 00E is providing LEU fuels to the 2MW Ford Nuclear Reactor (FNR) at the University of flicnigan for an in-core demonstration.
By letter dated April 2,1980, supplemented by letter dated June 26, 1980, the University of Michigan requested modifications to their license (R-29) to pemit the use of LEU fuels, an increase in fuels inventory, and a change to the Technical Specifications.
Two types of LEU fuel are planned for use in the 2MW FNR, aluminide and oxide fuel plates. LEU fuel elements to be delivered to the FNR for the initial core loading are anysically identical in dimensions to the existing MTR-type HEU fuel elements now in the core. The proposed LEU fuel is enriched to 19.5%
U-235. This initial demonstration will constitute a complete core loading of intemetallic uranium aluminide (UA1, UA1, UA1 ) clad in aluminum 6061.
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3 This fuel type is already licensed for use in the FRR and has been safely operated for approximately one year.
The fuel elements consist of MTR-type plates of 0.060 inches thickness.
The fuel meat thickness is increased to 0.030 inches from the HEU fuel thick-l ness of 0.020 inches and the clad thickress will be decreased to 0.015 inches l
from the HEU clad thickness of 0.020 f r.ches. This will maintain the same l
overall fuel plate thickness while accommodating the increased amount of U-238. In ordce to provide the preper U-235 loading, the weight percent of the fissile material in the fuel element is approximately 56.5 weight percent UAl or 49.6 weight percent U-Og.
Proposed uranium loading is 42.0 x
l weight percent. The fuel leading is increased from an existing value of 140 grams to 167.3 grams N 0-235 per 18-plate element to compensate for increased neutron absor cion in the U-238 and spectrum hardening.
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i, i The LEU fuel specifications are such that this fresh LEU core will exhibit the same excess reactivity as the existing HEU fueled core.
DISCUSSION Extensive testing experience is available from five test reactors that utilize components of the proposed LEU fuel to be used in the FNR. Extensive experience is also sailable from the 25-30 HEU fuel elements now in the FNR core.
The various test elements are described in Table 1.
The physical characteristics and coerating parameters of these fuels are similar to the croposed LEU fuels as shown in Table II.
Fuel Swelline The FMR SAR provides data on fuel swelling. The measured swelling rate is belew that which was calculated. As is expected, the measured swelling rate is less than the calculated, due to the presence of voids in the fuel which would tend to reduce the effects of swelling.
The available data indicated the proposed UA1 and.40: LEU fuels can be x
safely utilized in the FNR core at the proposed operating conditions without
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concern for swelling.
Th'e SER for Amendment No. 25 corroborated this assessment on the absence of swelling in the proposed fuel.
In addition the existing highly enriched UA1 fuel that is currently in the core shows no signs of swelling.
x Fuel Slistering The data provided in th FNR-SAR indicates that no blister failures will occur at FNR operating temperatures. This analysis was corroborated in the SER fuels.
for Amendment No. 25 for the use of high enrichment UAl
.and U 03g x
Fuel Soecifications l
l Fuel specifications are identical to those specified for ATR fuels and call for uranium aluminide powder containing at least 50% UA1
U033 when and if U 033 is used in the FNR.
l Densities The LEU fuels necessitate a higher weight percent of uranium alumir.ide (56.5 l
w/o UA1, 42.0 w/o U) than is presently used for the FNR high enrichment x
fuel of 19.1% w/o UAl,,.
However, the Advanced Test Reactor ( ATR) routinely f
operates using compariele aluminide fuel densities and obtains higher fission densities than the 1.5 x 1021 fissions /cc limit of the FNR.
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3 The SER perfomadfor Amendment No. 25 also indicated that the fission density limit of 1.5 x 10 was satisfactory.
Heat Transfer As indicated above, the external fuel element dimemions of the proposed LEU and existing HEU fuel elements are identical. Heat ' lux in the existing and proposed elements are identical. Peak fuel tempercure in the hottest fuel plate is calculated to be 172*F.
Design Basis Event The apolicant did not provide a DBE. For the type of reactor, power level and use, it was detemined by the staff and UM that a conservative OBE would be a LOCA. Though FNR operating temoeratures and pressures probably would never generate an accident of this type, the applicant has agreed to provide t% scenarios and thermodynamic calculations that will describe the impact and effects en the feul elements.
It was agreed by the staff that a DBE can be submitted at a later date. The acolicant has agreed to submit the necessary infomation by September 30, 1981. The staff nas further agreed that the reactor may operate during the preparation and review of the CBE.
Summary A review of an initial submittal performed indicated the need for additional information. This was provided in the formal response dated April 2,1980.
The modification of the Technical Specifications was supplied July 12, 1980.
The information provided in the response was subsequently reviewed together with the SAR and it was detemined that tnere will be no coerating conditions stemming from the use of LEU fuels in the FNR core that will produce risks that are any greater than those that have been evaluated in previous FNR accident analyses or safety analysis reports and found to be acceptable.
fuel specifications will be geometrically the same as the above The U,03 UA1x fuel; however, the final specifications will be developed in cooper-ation with ORAL and 3rockhaven National Laboratory to ensure standardization should this fuel be used in the FNR in the future.
The margin of safety is not reduced wnen the proposed UAl and U 033 fuels x
are operated in the FNR in accordance with requirements to be established 21 in the Tecnical Specifications E.d limiting the fission density to 1.5 x 10 fission /cc. The powder metallurgy manufacturing pro:ess is considered superior to alloying because of improved dimensional stability during reactor ope ation and the reduction in fuel hot spots.
We therefore agree that use of the UAl and U,03 fuels proposed by the x
University of Michigan in the FNR is acceptabfe.
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4 Environmental Consideration We have determined that this amendment will not result in any significant environmental impact and that it does not constitute a major Commission action significantly affecting the quality of the human environment. We have also determined that this actio6 is not one of those covered by 10 CFR 551.5(a) or (b). Having made these determinations, we have further concluded that, oursuant to 10 CFR 551.5(d)(4), an environmental impact statement or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
CCNCLUSICN We have concluded, based on the considerations discussed above, that: (1) because the amendment does not involve a significant increase in the prob-ability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, the amendment does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in comoliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: Februa ry 10, 1981 i
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