Neutron Activation Analysis of Thorium by the Use of the Japan Materials Testing Reactor

Hydraulic power rabbit in the Japan Materials Testing Reactor (JMTR) was used for highly sensitive neutron activation analysis of thorium in silica and aluminum. The thermal neutron flux of JMTR is higher than 1x10^n/cm^2/sec. A number of radioactive isotopes were made from impurities of high purity aluminum and silica irradiated in JMTR. ^Ta, which was produced from ^Ta by (2n, γ) reaction, was observed and made the determination of thorium difficult. The objective activation products ^Pa for the determination of thorium was isolated from majority of interfering radioactivity by a method combined with anion exchange and LaF_3 coprecipitation. It was found that the detection limit of thorium was less than 2x10^g. The method is useful to the analysis for thorium in high purity aluminum and silica that might be used to make very large scale integrated circuit

Radioactive contamination of several materials following the Fukushima Daiichi Nuclear Power Station accident

Following the 2011 accident at the Fukushima Daiichi Nuclear Power Station (NPS), which is owned by Tokyo Electric Power Co., radioactive nuclides were released into the environment and heavily contaminated the NPS site. In this study, the contamination behavior of radioactive nuclides in accumulated water, rubble, soil, and vegetation is discussed. Activity concentrations are converted to a “transport ratio,” which is the activity concentration ratio normalized using the activity in the source term for the nuclides of interest and a selected standard. The transport ratio of Sr to rubble and soil by way of air was approximately 10−2 to 10−3, and the successive transport to accumulated water was comparable with Cs (except for the initial release). Transport of Pu, Am, and Cm was lower than for Sr regardless of the transport process (air or water), whereas those of I, Se, and Te were comparable or greater. Contamination with 3H and 14C was independent of 137Cs, 90Sr, and TRU nuclides and was likely a result of different transport process

Safety operation of chromatography column system with discharging hydrogen radiolytically generated

In the extraction chromatography system, accumulation of hydrogen gas in the chromatography column is suspected to lead to fire or explosion. In order to prevent the hazardous accidents, it is necessary to evaluate behaviors of gas radiolytically generated inside the column. In this study, behaviors of gas inside the extraction chromatography column were investigated through experiments and Computation Fluid Dynamics (CFD) simulation. N2 gas once accumulated as bubbles in the packed bed was hardly discharged by the flow of mobile phase. However, the CFD simulation and X-ray imaging on γ-ray irradiated column revealed that during operation the hydrogen gas generated in the column was dissolved into the mobile phase without accumulation and discharged

Leakage of Octyl(Phenyl)--Di-Isobutylcarbamoylmethylphosphine Oxide from a Macroporous Silica-Based Chelating Polymeric Adsorption Material and its Recovery by Some Selected Porous Adsorbents

The leakage behaviour of a neutral chelating agent, i.e. octyl(phenyl)- N,N -di-isobutylcarbamoylmethylphosphine oxide (CMPO), from its macroporous silica-based (CMPO/SiO 2 -P) extraction resin (a novel polymeric adsorption material developed in the MAREC process) and the recovery of CMPO by some selected polymer- and silica-based porous adsorbents were investigated by column operation in 0.01 M HNO 3 at 25°C or 50°C. The concentration of CMPO in the effluent leaking from CMPO/SiO 2 -P was determined as ca. 48 ppm at 25°C and ca. 37 ppm at 50°C. The corresponding elution volumes and the amounts of CMPO leaking were 8700.9 BV/g and 239.3 mg/g at 25°C and 11 842.9 BV/g and 359.4 mg/g at 50°C, respectively. The adsorption experiment showed that a polymer-based porous material, SEPABEADS® SP-825, was capable of recovering CMPO effectively from 0.01 M HNO 3 . Its adsorption ability towards CMPO was considerably greater than those of macroporous silica-based SiO 2 -P particles, polymer-based Amberlite™ XAD-7 and activated carbon. The bed volume and the amount of CMPO adsorbed by SEPABEADS® SP-825 at the breakthrough point at 25°C were 13 549.2 BV/g and 498.7 mg/g, respectively, thereby demonstrating that SEPABEADS® SP-825 was promising for the recovery of CMPO from Am(III)- and Cm(III)-containing solutions in the MAREC process

Optimizing composition of TODGA/SiO2-P adsorbent for extraction chromatography process

AbstractAs a part of developing extraction chromatography technology for minor actinides (MA(III); Am and Cm) recovery from spent fast reactor fuels, improvement on the TODGA/SiO2-P adsorbent to enhance its desorption efficiency was carried out. Batchwise adsorption/elution experiments showed that optimizations in amount of the extractant impregnated in the support of the SiO2-P which is the porous silica coated with polymer and degree of the cross linkage of polymer succeeded in finding the optimum values. Inactive column separation experiments with the simulated high level liquid waste and the optimized adsorbent revealed that decontamination factors of fission products can also be improved as well as the recovery yields

Ten years after the NPP accident at Fukushima : review on fuel debris behavior in contact with water

International audienceFollowing the NPP accident, several hundred tons of heat-generating corium and fuel debris have been cooled permanently by millions of m3 of flowing. Knowledge on the interaction with water is cruc..