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Martin, P. G.*; Louvel, M.*; Cipiccia, S.*; Jones, C. P.*; Batey, D. J.*; Hallam, K. R.*; Yang, I. A. X.*; Satou, Yukihiko; Rau, C.*; Mosselmans, J. F. W.*; et al.
Nature Communications (Internet), 10, p.2801_1 - 2801_7, 2019/06
Times Cited Count：26 Percentile：79.27(Multidisciplinary Sciences)Synchrotron radiation (SR) analysis techniques alongside secondary ion mass spectrometry (SIMS) measurements have been made on sub-mm particulate material derived from reactor Unit 1 of the Fukushima Daiichi Nuclear Power Plant (FDNPP). Using these methods, it has been possible to investigate the distribution, state and isotopic composition of micron-scale U particulate contained within the larger Si-based ejecta material. Through combined SR micro-focused X-ray fluorescence (SR-micro-XRF) and absorption contrast SR micro-focused X-ray tomography (SR-micro-XRT), the U particulate was found to be located around the exterior circumference of the highly-porous particle. Synchrotron radiation micro-focused X-ray absorption near edge structure (SR-micro-XANES) analysis of a number of these entrapped particles revealed them to exist within the U(IV) oxidation state, as UO
, and identical in structure to reactor fuel. Confirmation that this U was of nuclear origin (
U-enriched) was provided through secondary ion mass spectrometry (SIMS) analysis with an isotopic enrichment ratio characteristic of a provenance from reactor Unit 1 at the FDNPP. These results provide clear evidence of the event scenario (that a degree of core fragmentation and release occurred from reactor Unit 1), with such spent fuel ejecta existing; (i) within the stable U(IV) oxidation state; and (ii) contained within a bulk Si-based particle. While this U is unlikely to represent an environmental or health hazard, such assertions would likely change, however, should break-up of the Si-containing bulk particle occur. However, more important to the long-term decommissioning of the reactors (and clean-up) on the FDNPP, is the knowledge that core integrity of reactor Unit 1 was compromised with nuclear material existing outside of the reactors primary containment.
Richards, M.*; Venneri, F.*; Shimakawa, Satoshi
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10
A key feature of the Very High Temperature Reactor (VHTR) is its use of ceramic, coated-particle fuel that can be irradiated at very high temperatures to very high burnup. In this paper we describe applications for deep-burn VHTRS (DB-VHTRs) using Pu, transuranic (TRU), and mixed oxide (MOX) fuels. One application is efficient and economic disposition of surplus weapons-grade Pu (WPu). A DB-VHTR using WPu fuel can consume about 65% of the WPu and about 90% of the Pu- 239 in a single pass through the core (corresponding to approximately 600 GWt-d/t). Comparable levels of burnup can be achieved using TRU material recovered from light water reactor (LWR) spent fuel. DB-VHTRs can also be deployed with Fast Breeder Reactors (FBRs) in a completely closed fuel cycle to provide both sustainability of nuclear fuel resources and flexible energy outputs, including hydrogen production and other process-heat applications.
Richards, M.*; Kunitomi, Kazuhiko
Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10
The FBR provides the fissile fuel for energy security and sustainability, and can be used to provide a significant portion of the electricity demand. The VHTR can provide flexible energy outputs with high efficiency, can operate with a wide variety of fuel cycles, and can be sited at locations that have limited availability of cooling water. These features, combined with its passive safety and high degree of proliferation resistance, make the VHTR an ideal complement for co-deployment with the FBR in Japan and also a very low-risk technology for export to foreign countries. In addition to hydrogen production, the VHTR can play a key role for significantly reducing greenhouse-gas emissions. This paper describes assessments for deploying FBRs and VHTRs in Japan using a closed fuel cycle, with the FBRs supplying the fissile material to sustain the combined FBR/VHTR fleet.
