USOO8475747B1 (12) United States Patent (10) Patent No.: US 8.475,747 B1 Johnson et al. (45) Date of Patent: Jul. 2, 2013 (54) PROCESSING FISSILE MATERAL (56) References Cited MIXTURES CONTAINING ZIRCONUM AND/OR CARBON U.S. PATENT DOCUMENTS 3,012,849 A 12, 1961 Horn ................................. 423.4 Inventors: Michael Ernest Johnson, Richland, WA 3,965,237 A * 6/1976 Paige .......... ... 423f4 (75) 2003. O156675 A1* 8, 2003 Venneri et al. ... 376/189 (US); Martin David Maloney, 2003/0234223 A1* 12/2003 Kuraoka et al. .... ... 210,660 Evergreen, CO (US) 2007,0290.178 A1* 12/2007 Baron et al. ....... ... 252/643 2008/022410.6 A1* 9, 2008 Johnson et al. ... 252/625 (73) Assignee: U.S. Department of Energy, 2010/0314592 A1* 12/2010 Bourg et al. .................. 252,636 Washington, DC (US) OTHER PUBLICATIONS General Atomics & US DOE, “Development Plan for Advanced High (*) Notice: Subject to any disclaimer, the term of this Temperature Coated-Particle Fuels'. http://nuclearinl.gov/ patent is extended or adjusted under 35 deliverables/docs/pc-000513 0 relpdf, 2003.* U.S.C. 154(b) by 784 days. Pereira, Candido. “UREX-- Process Overview” www.ne.doe.gov/ pdfFiles/DOENRCUREXSeminar.pdfSimilar, Mar. 26, 2008.* Del Cul et al. “TRISO Coated Fuel Processing to Support High (21) Appl. No.: 12/484,561 Temperature Gas-Cooled Reactors.” http://nuclear.gov/peis/refer ences/RM923 DelCuletal 2002.pdf, p. 1-62, Mar. 2002.* (22) Filed: Jun. 15, 2009 Minato et al. “Retention of fission product caesium in ZrC-coated fuel particles for high-temperature gas-cooled reactors.” J. Nuclear Materials, 279, pp. 181-188, 2000.* Related U.S. Application Data * cited by examiner (60) Provisional application No. 61/061,563, filed on Jun. Primary Examiner — Tri V Nguyen 13, 2008. (74) Attorney, Agent, or Firm — Michael J. Badagliacca: John T. Lucas (51) Int. C. G2IC 9/00 (2006.01) (57) ABSTRACT COIG 56/00 (2006.01) A method of processing spent TRIZO-coated nuclear fuel (52) U.S. C. may include adding fluoride to complex zirconium present in USPC ............... 423/7; 252/625; 252/636; 252/637; a dissolved TRIZO-coated fuel. Complexing the Zirconium 423/8; 423/9 with fluoride may reduce or eliminate the potential for Zirco (58) Field of Classification Search nium to interfere with the extraction of uranium and/or tran USPC .................. 252/500-645; 423/7-10; 376/189 Suranics from fission materials in the spent nuclear fuel. See application file for complete search history. 10 Claims, 7 Drawing Sheets Graphite Prismatic Spett Figel Beck -- Corerett Compacte &raphite Block first Sck isposition -- Crush/Mill Carton Fines Fuel Compacts and sideSilicon -- eaching 2, K, e. Dissolver Off-gas System Treatment Systern -- Solid origid Files ared other Separation Soids Disposition -- Organic Acid Oxidation --- reenin Complexing REX Sover Extraction U.S. Patent Jul. 2, 2013 Sheet 1 of 7 US 8.475,747 B1 alss Fue Kernei / / --/ N - Buffer layer (Porous Carbon Layer) /A / s - YS A/ e | l-k ra----------ar 1 inner Pyrocarbor (PyC lS-22S-ca Silicon Carbide (SiC) N u1 Outer Pyrocarbon (OPyC) ---.ar - - r (00 a.m. -> U.S. Patent Jul. 2, 2013 Sheet 2 of 7 US 8.475,747 B1 Graphite Prismatic Spent Fuel Block Core-out Cornpacts s Graphite Block Pre - Pro r y rr - r re. frei Eik se isposition crushAiii. Corf ines Y A XX w. XX X XV wo Fuel Compacts B indCofide Silico Dry Off-gas eaching NOx, 12, Kr, Xe Dissolver off-gas retiren Syster s Treatinent Syster Systern Solid on is is: MY *ies ind other Separation ser Solids isposition Organic Acid {}xistic Aircotiar Complexing RE-i Siyist Extractice US 8,475,747 B1 1. 2 PROCESSING FISSILE MATERAL kernel, oxidizing organic acids, extracting Zirconium from MIXTURES CONTAINING ZIRCONUM the dissolved fuel kernel, and processing the dissolved fuel AND/OR CARBON kernel by at least one or more of the following processes: CCD-PEG, FPEX, TRUEX, and TALSPEAK. CCD-PEG is CROSS REFERENCE TO RELATED an acronym for chlorinated cobalt dicarbollide polyethylene APPLICATION glycol. FPEX is an acronym for Fission Product Extraction. TRUEX is an acronym for Transuranic Extraction. TAL This application claims priority from U.S. Provisional SPEAK is an acronym for Trivalent Actinide Lanthanide Application Ser. No. 61/061,563 filed Jun. 13, 2008. Separations by Phosphorous-reagent Extraction from Aque 10 ouS K complexes. The fuel compact may include at least the STATEMENT REGARDING FEDERALLY carbon fines, the silicon carbide, and the fuel kernel. SPONSORED RESEARCH ORDEVELOPMENT While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent The United States Government has rights in this invention, to those skilled in the art from the following Detailed Descrip as represented by the U.S. Department of Energy, pursuant to 15 tion, which shows and describes illustrative embodiments of agreement DE-FC01-07NE24502. the invention. As will be realized, the invention is capable of modifications in various aspects, all without departing from FIELD OF THE INVENTION the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illus The present disclosure relates to processing nuclear mate trative in nature and not restrictive. rial. More specifically, the present disclosure relates to the processing of fissile material mixtures containing Zirconium BRIEF DESCRIPTION OF THE DRAWINGS and/or carbon and methods and systems for Such processing. FIG. 1 depicts a coated particle fuel kernel. BACKGROUND OF THE INVENTION 25 FIG. 2 depicts a flow chart of one embodiment of the steps for processing TRIZO-coated fuels. Nuclear power plants generate spent nuclear fuels (SNF). FIG. 3 depicts a functional flow diagram for the UREX SNF typically contains uranium, and other radioactive process. actinide elements such as neptunium, plutonium, americium FIG. 4 depicts a functional flow diagram for the chlorinated and curium, radioactive rare earth elements, the radioactive 30 cobalt dicarbollide polyethylene glycol (CCD-PEG) process. transition metal technetium, as well as radioactive cesium and FIG. 5 depicts a functional flow diagram for the TRUEX strontium. feed adjustment and TRUEX process. The spent nuclear fuel may be in the form of a fuel kernel FIG. 6 depicts a functional flow diagram for the TAL or particle and may include a coating, Such as a TRISO-coated SPEAK process. particle fuel or a TRIZO-coated particle fuel. TRISO is an 35 FIG. 7 depicts a functional flow diagram for the ZrTcPX acronym for TRI-structural, ISOtropic, with the coatings process. being a buffer, Such as low-density pyrolytic carbon, high density pyrolytic carbon (IPyC and OPyC), and silicon car DETAILED DESCRIPTION bide (SiC). TRIZO-coated particle fuel is similar to the TRISO-coated particle fuel and includes a thin layer of Zir 40 The disclosure is directed to methods of processing fissile conium (ZrO) deposited on the kernel and/or in the buffer material mixtures, such as TRIZO-coated particle fuel. In one layer. The coating serves as a miniature pressure vessel that aspect, the processing method includes the addition of fluo provides containment of radionuclides and gases. ride anions to complex zirconium present in a dissolved The spent nuclear fuel may be processed to separate reus TRIZO-coated fuel. The complexing of zirconium with fluo able transuranics and uranium from the fission products. The 45 ride may prevent, or otherwise reduce the potential of inter TRIZO-coated fuels contain Zirconium (Zr) in the fuel kernel ference of the UREX (uranium extraction) and TRUEX coatings. Zirconium may contaminate the uranium and tech (TRU, or transuranic extraction) solvent extraction processes netium or the transuranics separated from the TRIZO-coated by Zirconium. The processing method may also include a step fuels during processing. for oxidation of organic acids. 50 In another aspect, the processing method includes a solvent BRIEF SUMMARY OF THE INVENTION extraction processing step called ZrTcEX (Zirconium techne tium extraction). The ZrTcPX process may be applied to Described herein are methods for processing TRIZO TRIZO-coated particle fuels that are made from oxides of coated spent nuclear fuels. One method may include remov transuranics (TRU) that do not contain uranium or where ing a fuel compact from a graphite spent TRIZO-coated fuel 55 uranium recovery is undesirable. The process co-extracts Zir block, separating carbon fines and silicon carbide from a fuel conium and technetium from the dissolved TRIZO TRU kernel, dissolving the fuel kernel, separating Solids from the oxide fuels. If uranium is also present in the TRIZO-coated dissolved fuel kernel, oxidizing organic acids, complexing fuel, uranium is co-extracted with Zirconium and technetium. zirconium with fluoride, and processing the dissolved fuel A step for oxidizing the organic acids may also be included in kernel using a solvent extraction process to separate fission 60 the processing method. products from uranium and transuranics. The fuel compact With reference to FIG. 1, a coated fuel kernel may include may include at least the carbon fines, the silicon carbide, and an inner fuel kernel that provides fission energy and controls the fuel kernel. oxygen potential. TRIZO-coated (and TRISO-coated) fuel Yet another method may include removing a fuel compact kernels can include uranium oxide, mixed uranium and plu from a graphite spent TRIZO-coated fuel block, separating 65 tonium oxide, plutonium oxide, TRU oxides, or other fissile carbon fines and silicon carbide from a fuel kernel, dissolving materials (e.g. thorium). For the TRU oxide fuel, the Pu-239 the fuel kernel, separating solids from the dissolved fuel and Pu-241 content of the TRU functions as the fissile mate US 8,475,747 B1 3 4 rial and the remaining nuclides function as fertile material Nuclear Company, Inc., Idaho Falls, Id., which is hereby and/or contribute to reactivity control during burn-up.