ISSN:
1662-0356
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Natural Sciences in General
,
Technology
Notes:
To immobilize the halide and actinide ions present in four Intermediate Level Waste (ILW)waste-streams the following process has been developed at AWE. The waste streams areinitially calcined with CaHPO4 to yield apatite which is then sintered with a sodiumaluminophosphate glass to produce a monolithic wasteform. As each waste streamcomposition is expected to vary widely it is necessary to determine the safe limits of wasteloading at which the actinides will be adequately immobilized via this solid state synthesisroute.In these initial non-active studies hafnium was used as a surrogate for plutonium. Sampleshaving nominal composition (Ca10-2xHfx)F2(PO4)6 (x = 0, 0.125, 0.25, 0.5, 0.75, 1.0 and1.25) were prepared at 850 and 1050 °C. These were studied by XRD to determine thephase assemblage and solid solution limits in the apatite phase.Phase pure fluorapatite (Ca10F2(PO4)6) was obtained at 1050 °C (x = 0). At x = 0.125, onXRD patterns, additional reflections assigned to HfO2, Ca0.5Hf2(PO4)3 and Ca3(PO4)2 wereobserved. Proportions of these phases increased with x.Synthesis at 850°C (x = 0), yielded a two phase mixture of Ca10F2(PO4)6 and β-Ca2P2O7.At x ≥ 0.250 HfO2 was detectable by XRD, thereafter proportions of HfO2 and β-Ca2P2O7increased with x
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.2018.pdf
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