NRC Generic Letter 1986-12
°> UNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D. C. 20555July 3, 1986TO: ALL NON-POWER REACTOR LICENSEES AUTHORIZED TO USE HEU FUELSUBJECT: CRITERIA FOR UNIQUE
PURPOSE
EXEMPTION FROM CONVERSION FROM THEUSE OF HEU FUEL (GENERIC LETTER 86-12)10 CFR 50.64 (51 FR 6514) provides for a "unique purpose" exemption fromthe requirement to convert from the use of high enriched uranium (HEU) fuel,provided the licensee presents a Justification that is accepted by theCommission. Amended 10 CFR 50.2 gives broad definitions for acceptableunique purposes. This letter provides more specific guidance for thoselicensees who believe they might qualify for such an exemption.The definition states that a unique purpose means a project, program, orcommercial activity that cannot be reasonably accomplished without the useof HEU fuel, and may include one or more of the following four purposes:1) A specific experiment, program, or commercial activity (typicallylong-term) that significantly serves the U.S. national interest andcannot be accomplished without the use of HEU fuel;2) Reactor physics or reactor development based explicitly on the use ofHEU fuels;3) Research projects based on neutron flux levels or spectra attainableonly with HEU fuel; or4) A reactor core of special design that could not perform its intendedfunction without using HEU fuel.The definition provides guidance to licensees who believe they might qualifyfor a unique purpose exemption to develop a basis for exemption that bestfits each unique situation, and which would provide a Justification that theCommission could find acceptable. These four purposes are not necessarilythe only ones that might form the basis for a unique purpose exemption.However, the following discussion relates to the four given in the 10 CFR50.2 definition.
Purpose
number 1 is intended to relate primarily to technical activitiesclosely coupled to the national interest, which might include preeminencein a specific field of research or assurance of a domestic supply of someessential product of reactor operation. This was included in the definitionof "unique purpose" to help provide the Nuclear Regulatory Commission (NRC)wide latitude of discretion like the standards in 10 CFR 50.41.8607030269 ZA D7ILTIZ
-2 -Of the four purposes identified, it is intended that numbers (2) and(4) provide opportunity to perform new reactor projects whoseobjectives were to learn about or develop reactor concepts for whichparameters of HEU were a necessary component. Examples might be a uniquecompact reactor heat source, a compact pulsing reactor with minimaldistortion of fast neutron spectra, or a comparison of HEU and low enricheduranium (LEU) operating cores for assessing the potential for conversionsof non-power reactor cores.
Purpose
number 3 is intended to provide the opportunity to continueusing HEU fuel if converting to available LEU fuel would change neutronflux densities or spectra, or other essential radiation parameters, so thatthe fundamental reason for conducting the reactor-based program would belost, or irreparably compromised.
Purpose
number 4 might also pertain to a non-power reactor that wasdesigned and is operated to take maximum advantage of the uniquecharacteristics of HEU fuel and where the substitution of any available LEUfuel could not be made without major facility modification to accommodatesuch things as a larger core, different coolant systems, or major changesin its primary mode of operation. An example would be a core with specificphysical size limits that currently uses near-maximum uranium density in itsfuel.An application for exemption from conversion from HEU fuel must be submittedto the Director, Office of Nuclear Reactor Regulation, in accordance withthe schedule given in the published regulation. The application shouldspecify the date when acceptable LEU or medium enriched uranium (MEU) fuelis expected to be available, and a conversion schedule provided whereappropriate. The NRC expects that only very few licensees will qualify forexemption. The following are examples of items which should be consideredand developed in detail, as appropriate, in any application for exemption:(1) Identification and outline of the program(2) Explanation of the value of the program and any special experimentsto the U.S. national interests(3) Discussion of how the achievement of significant and competitiveresults is dependent on such factors as the following:(a neutron fluence (e.g., power level and operating schedule)b neutron flux density (e.g., power level, core size)c neutron spectrad signal-to-noise ratio in the experimental resultse) operating and refueling schedule for the reactorf) operating costs(g) waste management(4) Discussion of program accomplishment with available LEU fuels, andspecification of LEU fuel characteristics required to permitcontinuation of the programs with no significant decrement inaccomplishment.
-3 -This letter is for guidance only in interpreting 10 CFR 50.64. No responseor action is necessary other than that required by the regulation to applyfor a unique purpose exemption.Questions should be addressed to Mr. Robert E. Carter at (301) 492-8206.Original signed byPrank J, Kiregl8AFrank J. Miraglia, DirectorDivision of PWR Licensing-BDISTRIBUTION:Central File-NRC PDRsLocal PDRSSPD ReadingPNoonanRCarterDTondiHBerkowOELDFMiragliaHYoung, ER, DO*SEE PREVIOUSDPWRL-B:SSPD*PNoonan06/19/86)E V, 01¢0 /sCONCURRENCE SHEETDPWRL-B:SSPD* DPWRL-B:SSPD*RCarter:ac DTondi06/19/86 06/20/86DPWRL-B:SSPD*HBerkow06/20/86OELD*TDorian06/24/86