1. Graduate School of Applied Chemistry, Faculty of Science and Engineering, Waseda University, Tokyo 169-8555, Japan; 2. Japan Atomic Energy Agency, Ibaraki 319–1194, Japan
In the dissolution step of spent nuclear fuel, there is a world-concern problem that zirconium molybdate hydrate precipitates as a byproduct, and accumulates in some reprocessing equipments. In order to prevent this accumulation, we have developed a new method based on the controlled reaction crystallization of zirconium molybdate hydrate (ZMH) in the reprocessing solution, followed by solid liquid separation. In order to measure the particle size of ZMH, batch crystallization experiments were conducted by varying nitric acid concentration and operating temperature. In result, almost all particle sizes scatter around 1 μm on average, despite the higher concentration of nitric aid and operating temperature, and then small particles grow up as an aggregate sticking to the crystallizer. Moreover, polymorph and color changing were observed by varying the concentration of nitric acid and reaction time. These results suggest that crystal color and adhesiveness are closely related to the particle size of ZMH. And the control of nitric acid concentration and small particle growth would be the useful technique to prevent the ZMH sticking.
Kubota M, Fukase T. Formation of precipitate in high-level waste from nuclear fuel reprocessing. Journal of Nuclear Science and Technology , 1980, 17(10): 783–790 doi: 10.1080/18811248.1980.9732654
2
Cansheng L. Study of precipitation behavior of Mo and Zr in nitric acid solution. Journal of Nuclear Radiochemistry , 1992, 14: 24–30
3
Doucet F J, Goddard D T, Taylor C M, Denniss I S, Hutchison S M, Bryan N D. The formation of hydrated zirconium molybdate in simulated spent nuclear fuel reprocessing solutions. Physical Chemistry Chemical Physics , 2002, 4(14): 3491–3499 doi: 10.1039/b201792j
4
Usami T, Tsukada T, Inoue T, Moriya N, Hamada T, Serrano Purroy D, Malmbeck R, Glatz J P. Formation of zirconium molybdate sludge from an irradiated fuel and its dissolution into mixture of nitric acid and hydrogen peroxide. Journal of Nuclear Materials , 2010, 402(2–3): 130–135 doi: 10.1016/j.jnucmat.2010.05.008
5
Magnaldo A, Masson M, Champion R. Magnaldo. Nucleation and crystal growth of zirconium molybdate hydrate in nitric acid. Chemical Engineering Science , 2007, 62(3): 766–774 doi: 10.1016/j.ces.2006.08.076
6
Chater J. Waste not, want not: nuclear reprocessing and stainless steel. Stainl Steel Wold JST , 2005, 17: 42–47
7
Recktenwarld G D, Deinert M R. Cost probability analysis of reprocessing spent nuclear fuel in the US. Energy Econ JST , 2012, 34(6): 1873–1881 doi: 10.1016/j.eneco.2012.07.016
8
Baja B, Varga K, Szabó N A, Németh Z, Kádár P, Oravetz D, Homonnay Z, Kuzmann E, Schunk J, Patek G. Long-term trends in the corrosion state and surface properties of the stainless steel tubes of steam generators decontaminated chemically in VVER-type nuclear reactors. Corrosion Science , 2009, 51(12): 2831–2839 doi: 10.1016/j.corsci.2009.08.007
9
Matsumura K, Kawamura W, Miyake T. JP Patent, 2000-56077 (2000.02.25)
