ASTM_C_1431_-_99_2018.pdf

Designation:C143199(Reapproved 2018)Standard Guide forCorrosion Testing of Aluminum-Based Spent Nuclear Fuel inSupport of Repository Disposal1This standard is issued under the fixed designation C1431;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide covers corrosion testing of aluminum-basedspent nuclear fuel in support of geologic repository disposal(per the requirements in 10 CFR 60 and 40CFR191).Thetesting described in this document is designed to provide datafor analysis of the chemical stability and radionuclide releasebehavior of aluminum-based waste forms produced fromaluminum-based spent nuclear fuels.The data and analysesfrom the corrosion testing will support the technical basis forinclusion of aluminum-based spent nuclear fuels in the reposi-tory source term.Interim storage and transportation of thespent fuel will precede geologic disposal;therefore,referenceis also made to the requirements for interim storage(per 10CFR 72)and transportation(per 10 CFR 71).The analyses thatwill be based on the data developed are also necessary tosupport the safety analyses reports(SARs)and performanceassessments(PAs)for disposal systems.1.2 Spent nuclear fuel that is not reprocessed must be safelymanaged prior to transportation to,and disposal in,a geologicrepository.Placement in an interim storage facility may includedirect placement of the irradiated fuel or treatment of the fuelprior to placement,or both.The aluminum-based waste formsmay be required to be ready for geologic disposal,or roadready,prior to placement in extended interim storage.Interimstorage facilities,in the United States,handle fuel from civiliancommercial power reactors,defense nuclear materials produc-tion reactors,and research reactors.The research reactorsinclude both foreign and domestic reactors.The aluminum-based fuels in the spent fuel inventory in the United States areprimarily from defense reactors and from foreign and domesticresearch reactors.The aluminum-based spent fuel inventoryincludes several different fuel forms and levels of235Uenrichment.Highly enriched fuels(235U enrichment levels20%)are part of this inventory.1.3 Knowledge of the corrosion behavior of aluminum-based spent nuclear fuels is required to ensure safety and tosupport licensing or other approval activities,or both,neces-sary for disposal in a geologic repository.The response of thealuminum-based spent nuclear fuel waste form(s)to disposalenvironments must be established for configuration-safetyanalyses,criticality analyses,PAs,and other analyses requiredto assess storage,treatment,transportation,and disposal ofspent nuclear fuels.This is particularly important for the highlyenriched,aluminum-based spent nuclear fuels.The test proto-cols described in this guide are designed to establish materialresponse under the repository-relevant conditions.1.4 The majority of the aluminum-based spent nuclear fuelsare aluminum clad,aluminum-uranium alloys.The aluminum-uranium alloy typically consists of uranium aluminide particlesdispersed in an aluminum matrix.Other aluminum-based fuelsinclude dispersions of uranium oxide,uranium silicide,oruranium carbide particles in an aluminum matrix.Theseparticles,including the aluminides,are generally cathodic tothe aluminum matrix.Selective leaching of the aluminum inthe exposure environment may provide a mechanism forredistribution and relocation of the uranium-rich particles.Particle redistribution tendencies will depend on the nature ofthe aluminum corrosion processes and the size,shape,distri-bution and relative reactivity of the uranium-rich particles.Interpretation of test data will require an understanding of thematerial behavior.This understanding will enable evaluation ofthe design and configuration of the waste package to ensurethat unfilled regions in the waste package do not provide sitesfor the relocation of the uranium-rich particles into nuclearcritical configurations.Test samples must be evaluated,prior totesting,to ensure that the size and shape of the uranium-richparticles in the test samples are representative of the particlesin the waste form being evaluated.1.5 The use of the data obtained by the testing described inthis guide will be optimized to the extent the samples mimicthe condition of the waste form during actual repositoryexposure.The use of Practice C1174 is recommended forguidance.The selection of test samples,which may be unagedor artificially aged,should ensure that the test samples andconditions bound the waste form/repository conditions.Thetest procedures should carefully describe any artificial agingtreatment used in the test program and explain why thattreatment was selected.1This guide is under the jurisdiction of ASTM Committee C26 on Nu