Sadamitsu Tanzawa

PFC recycling system by continuous gas chromatography

We propose a new system to reduce emissions of Perfluorocompounds (PFCs) from semiconductor industries by continuous gas chromatography technology. For example, the recycling technology that was suggested before, such as cryogenic distillation, has some problems in its repurification step. It needs a huge distillation tower and much power for refrigeration. The continuous gas chromatography technology is a compact alternative to the conventional technology. This system is composed of the series of separation columns, vacuum pumps, and sequentially controlled valves. The mixture of PFCs is separated by the difference of the affinity for the filling material in the column. Only pure PFCs separated perfectly are outputs and the others are injected to the next column. By recycling the mixture of PFCs, which was not separated by single column, the continuous gas chromatography outputs the pure PFCs continuously. Moreover, it can experimentally separate CF/sub 4/-NF/sub 3/, which cannot be separated by a cryogenic distillation. Based on the accumulation and consideration of experimental data, we realized the continuous efficient separation of CF/sub 4//C/sub 2/F/sub 6/ with the large-scale pilot plant of the continuous gas chromatography. In this method, a high recovery rate of more than 99% was obtained and residual C/sub 2/F/sub 6/ in recovered CF/sub 4/ and residual CF/sub 4/ in recovered C/sub 2/F/sub 6/ were less than 0.01%. This recycling system is compact and it can operate with low-energy consumption.

Fuel behavior in simulated RIA under high pressure and temperature coolant condition

Abstract Fuel behavior in simulated reactivity initiated accident (RIA) was studied under high pressure and temperature coolant condition of LWR operating environment. Test fuel rods were pulse-irradiated in the Nuclear Safety Research Reactor (NSRR) to simulate transient power generations at RIAs. From the results, it was clarified that the cladding collapsed under high external pressure but that the basic mechanisms and threshold enthalpies of incipient fuel failure were not different from those observed in the tests conducted under atmospheric pressure, room temperature and stagnant condition.

Effects gap heat transfer on LWR fuel behavior during an RIA transient: In-pile experimental results with helium and xenon fillet rods

Abstract Gap heat transfer characteristics and their effects on LWR fuel behavior during an RIA have been studied through the in-pile experiment with UO 2 pellet fuel rods. The report describes the experimental results obtained in the NSRR tests in which PWR type test fuel rods of helium and xenon filled as the gap gas have been irradiated in the pulse reactor, NSRR, to simulate the prompt heat up of RIAs. The relation between the cladding temperature history and the gap heat transfer conditions, and the effects of gap gas composition on fuel behavior and on the fuel failure threshold are discussed based on the in-pile experimental data.

Repeated Impact Test on Plasma Sprayed Alumina Insulation Film for Fusion Reactor.

The adhesive strength of insulation films for fusion reactor is important from the view point in which the durability is improved. In the present study, the adhesive strength of a plasma sprayed alumina insulation film coated on the stainless steel substrate was investigated by using a repeated impact test. The impact tests were performed at 3 kinds of mean impact pressure, 3, 5 and 12 times as large as the yield strength of the substrate, about 200MPa, in 2 surface materials combinations of alumina/alumina and alumina/bear stainless steel. In the alumina/alumina combination, the durability of the alumina films were over 30, 000 cycles at the mean impact pressures of 3 and 5 times, and we confirmed sufficiently high adhesive strength of the alumina film. And the alumina/stainless combination improved the durability of the alumina film by a factor of 2.7. While at the mean impact pressure of 12 times, because the stainless steel substrate gave rise to a plastic strain being 2 orders higher than the allowable strain of the alumina films, the alumina film was fractured by the propagation of cracks.