[en] In this paper, the authors studied the temperature distribution in a shipping cask for spent nuclear fuels at LOCA (loss-of-coolant accident) after a failure of the cask. The calculation was made on a model of a uni-axial (in radial direction) thermal transfer. The result shows that the decay heat which cannot be cooled down will cause the temperature to go over 1000⁰C at the central part of the cask. A very dangerous accident will occur at such a high temperature; i.e., the vapor of cesium, a radioactive isotope, will flow out from the cask into air, and the water-metal reaction will produce a great deal of heat and hydrogen. Because of this, the nuclear fuels at the central part will collapse and melt down. (author)

[en] In this paper, the authors studied on the temperature distribution in the shipping cask of spent nuclear fuels at LOCA (loss-of-coolant accident) by a failure of the cask. The calculation was made on a model of a radial thermal transfer. The result shows that the decay heat which cannot be cooled down will make the temperature over 1,000⁰C at the central part of the cask. A very dangerous accident will occur at such high temperature, i.e., cesium, a radioactive isotope, will be vaporized to flow out from the cask into air, and the fuel cladding pipes will bring about the water-metal reaction to produce a great deal of heat and hydrogen, by which the nuclear fuels at the central part will collapse and melt down. (author)

[en] It is important to prevent the buckling of thin pipes caused by an external pressure in the heat-exchanger system of a pressurized water reactor. The design code in ASME Sec. III NB considers this point. However, the thickness of pipes is partially thinned down by steam-liquid flow in service, and in design step no consideration is being paid to such a partially thinned down pipe, though much attention should be paid on this point. In this paper, the pressure at failure of a partially thinned pipe under an external pressure was studied. The experimental results show that the failure occurs at unexpectedly small pressure, if the thinned part has some expansion in area, and that the pressure at failure does not follow with the buckling equation given by elastic theory for thin cylinders. (author)

[en] The substitution reaction of [1-B₁₀H₉(N₂)]^- with N,N-dimethylthioformamide and the acid-catalyzed nucleophilic substitution of [B₁₀H₁₀]^2- with tetramethylthiourea gave [1-B₁₀H₉(SCH=NMe₂)]^- and [2-B₁₀H₉braceSC(NMe₂)₂brace]^-, respectively. The basic hydrolysis of these thioamide complexes yielded the 1- and 2-isomers of [B₁₀H₉(SH)]^2-respectively. Their stereochemistry was determined by ¹H n.m.r. spectroscopy from the S-Me chemical shift values of their S-methyl derivatives. (author)

[en] Cockayne syndrome (CS) is a rare autosomal recessive disease, which shows diverse clinical symptoms such as photosensitivity, severe mental retardation and developmental defects. CS cells are hypersensitive to killing by ultraviolet (UV)-irradiation and defective in transcription-coupled repair. Two genetic complementation groups in CS (CS-A and CS-B) have been identified. We analyzed mutations of the CSA gene in 5 CS-A patients and identified 3 types of mutations. Four unrelated CS-A patients (CS2OS, CS2AW, Nps2 and CS2SE) had a deletion including exon 4, suggesting that there is a founder effect on the CSA mutation in Japanese CS-A patients. Patient CS2SE was a compound heterozygote for this deletion and an amino acid substitution at the 106th glutamine to proline (Q106P) in the WD-40 repeat motif of the CSA protein, which resulted in a defective nucleotide excision repair. Patient Mps1 had a large deletion in the upstream region including exon 1 of the CSA gene. Our results indicate that a rapid and reliable diagnosis of CSA mutations could be achieved in CS-A patients by polymerase chain reaction (PCR) or PCR-restriction fragment length polymorphism (RFLP) and that the Q106P mutation could alter the propeller structure of the CSA protein which is important for the formation of the CSA protein complex. (author)