ML19331C060
| ML19331C060 | |
| Person / Time | |
|---|---|
| Site: | Rhode Island Atomic Energy Commission |
| Issue date: | 07/31/1980 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19331C053 | List: |
| References | |
| NUDOCS 8008140109 | |
| Download: ML19331C060 (5) | |
Text
-
~[ / ga << <,,IS UNITED STATES
'i NUCLEAR REGULATORY COMMISSION p'!
y WASHWGToN, D. C. 20555 s.* 3 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 8 TO FACILITY OPERATING LICENSE NO. R-95
',HODE ISLAND AND PROVIDENCE PLANTATIONS ATOMIC ENERGY COMMISSION RHODE ISLAND NUCLEAR SCIENCE CENTER REACTOR DOCKET NO. 50-193 Introduction 0)
By letter dated September 5,1979
, the Rhode Island and Providence Plantations Atomic Energy Comission (the licensee) proposed changes to Sections E and X of the Appendix A Technical Specifications of Facility Operating License No. R-95.
The proposed changes would allow the use of both uranium aluminide (UAlv) fuel and uranium oxide (U 0 ) fuel in addition to the uranium-aluminum (UA1) alloy 38 fuel that is presently being used in the Rhode Island Nuclear Science Center 21 fissions /cc.
(RINSC) reactor, and would specify a fission density limit of 0.5x10 Rod worths and reactor core flux distributions will be unaffected since these characteristics will be unchanged. The aluminide or oxide fuel elements will dimensionally be exactly the same as tha current alloy elements. The thermal and 6;ydraulic characteristics of the reactor will, therefore, be unchanged as well.
The licensee's safety analysis relies heavily on the safety analysis develooed by the University of Michigan for the Ford Nuclear Reactor (FNR)(2) in support of a similar license amendment authorizing the use of UAi and U 038 fuel at that x
facility. Because the two proposals are essentially identical, with the exception of those plant-specific differences discussed below, we conclude that the Safety Evaluation issued by the NRR on October 12, 1973 for the FNR(3) is equally valid for the proposed action at RINSC.
Evaluation General The licensee states that authorization to operate using UAlx or U 033 fuel is necessary tecause there is presently no domestic commercial vendor capable of producing the alloy type fuel required by the technical scecifications. The and U 0g) fuel is well developed and tecnnology for powdered metallurgy (UAl 3
x offers advantages not possible wnen using alloy fuel.
It produces a more uniform dispersicn of uranium throughout the aluminum matrix and provides better control of tne fuel plate uranium content than can be obtained with uranium-aluminum alloy.
'0008140W e
. Operating experience using these fuels in several reactors which operate at much higher thermal power densities, higher fission densities, higher heat fluxes and higher coolant flow rates than exist in the RINSC reactor, has demonstrated their satisfactory performance and reliability.
Differences Between the RINSC Reactor and FNR Fuel plate Geometry The Rhode Island fuel elements are made up of flat plates, rather than curved plates as at Michigan and are not as stable should moderate fuel swelling occur. However, several conservatisms exist that combine to render fuel swelling less of a problem at Rhode Island than at Michigan. Aluminide and oxide fuels exhibit lower swelling rates than alloy fuels.
In the former, swelling rate decreases with increasing uranium concentration due to the fact that void fraction of the fuel plates tends to increase with increasing uranium content. For fuel plates with higher void fractions, early core life swelling is absorbed by the voids and the onset of swelling is delayed until later in core life. In comparing aluminide and oxide fuels, tests have shown that plates containing aluminide dispersions consistently swelled more than plates containing the U 038 dispersions when irradiated.to comparable burnup levels.
The RINSC reactor aluminide fuel is to be composed of 26 weight percent uranium ccmpared to 14 weight percent at FNR, resulting in a higher void fraction and increased resistance to swelling. At a -fission density of 1.5x1021 fissions /cc and a void content of 4%, as at FNR, irradiation swelling of alumin'de fuel is expected to be less than 75 AV/V. RINSC reactor, with a void content somewhat higher than 41 and a fission density of 0.5xlC21 fissions /cc, is not expected to experience any fuel swelling with aluminide fuels.
Fission product inventory-should also be substantially less at Rhode Island than at Michigan because the RINSC reactor will be ocerated to a lower fuel burnup level (15.35) than FNR (355).
U-235 rer Element (gm)
The RINSC e.enent contains only 124 grams of U-235 with a neat thickness of
.012", as opposed to 140 This results in a larger core, grams with a meat thickness of.020" for FNR.
lower power density, smaller burnup (15.35 vs 35%
for Michigan) and lower f2el element surface temperature (150*F vs 159'F) for the RINSC reactor. iiis produces a more_ conservative condition than in the F'lR.
For UAl and U 033 fuel, fuel core blistering at a given burnuo is x
dependent :n 0:erating temperature. Under operating conditions similar to those in the FNR and for burnups above 1.5x1021, the temcerature for blister formation is greater than 900*F.
The conservatisms of the RINSC reactor listed above, comoined with a fission density limit of 0.5x1021 fissions /cc, make fuel alisterinr at the RINSC reactor even more unlikely than at FNR.
O y
-.g
--r
. Core Weight cercent Uranium The RINSC core utilizes elements with 26 weight percent uranium in the fuel meat as compared to 14 percent for the Michigan element. This is below what has been utilized in other reactors and is well within the capability of the technology for both UAlx and U 033 fuel.
Summary In summary, the margin of safety is not reduced when the procosed UAl and x
U0 fuels are operated in the RINSC reactor in accordance with re,Jirements 38 establishqj fission /cc.in the technical specidications and limiting the fission density to 0.5x10' The powdered metallurgy manufacturing process is considered superior to alloying because of improved dimensional stability during reactor operation and the reduction in fuel hot spots.
The use of UAl and U 033 fuel in a research reactor of similar design has x
been previously evaluated and was found to be acceptable under conditions less conservative than those at the RINSC reactor. We therefore agree that use of the UAl and U 033 fuels pecposed by Rhode Island AEC in the RINSC x
reactor is also acceptable.
Ocerating the FNR with UAl Alloy Fuel to the Procosed Fission Density Limit Rhode Isisnd AEC's Technical Specifications do not specify a fission density limiting condition for coeration for the UAl alloy fuel in the RINSC reactor.
Establishing a limit of 0.5x1021 fissions /cc is therefore conservative.
An analysis was never performed to establish a fission density limit for this fuel because the RINSC reactor can only achieve about 0.44 to 1021 fissions /cc with the present U 2 loading. Rhode Island AEC has operated at this level withoutfuelelemenk5 failures or other safety problems. We also have information from the General Electric Test Reactor, that also uses the UAl alley fuel, that it has operated at fission densities up to 2.0x1021 fissions /cc without any failures.
We agree that establishing a fission density limit of 0.5x1021 fissions /cc for UAl alloy fuel is conservative and therefore, acceptacle. Based on use of uranium aluminide and uranium oxide fuels a*1 fission densities well above 1.5x1021 without failure, a limit of 0.5x102 fissions /cc for UAl and U 033 is x
also conservative and acceptable.
Envircnmental Consideration We have determined that this amendment will not result in any significant environmental impact and that it coes not constitute a major Commission action significantly affecting the quality of the human environment. We have also determined that Onis action is not one of those covered by 10 CFR i 51.5(a) or (b). Having made these determinations, we have further concluded that, pursuant to 10 CFR 5 51.5(d)(J), an environmental impact statement or negative declaration and environmental impact acoraisal need not be precared in connection with the issuance of this amendment.
-w w
e
-a
-c, y,~
4-Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendment does not involve a significant increase in the probability or consequence of accidents previously considered and 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 compliance with the Commission's regulations and the issuance i
of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated:
i t
p
~
--,r m
w 9e-nen4 g-m
,w, m
,. ---,-w
-w-ye me w-
, - - +
References
- 1) Letter from DiMeglio, Rhode Island AEC to Reid, NRC, dated September 5,1979, Requesting amendment to Reactor License R-95, Occket 50-193 to allow use of uranium-aluminide and uranium oxide fuel in addition to uranium alloy fuel.
2} " Safety Analysis - Utilization of Intermetallic Uranium Aluminide (UA1, 3
UA1, UAl ) and Uranium Oxide (U3 9) Cermet Fuel Cores in the Ford Nuclear 4
2 0
Reactor " June 1977, revised 4/20/78, transmitted by letter from W. Kerr, University of Michigan to R. W. Reid, NRC, dated 6/12/78.
- 3) " Safety Evaluation by the Office of Nuclear Reactor Regulation Supporting Amendment No. 25 to Facility Operating License No. R-N, the University of Michigan, Ford Memorial Reactor, Occket No. 50-2," dated October 12, 1978.
I r
9
.. m.
.