[en] The possibility of electrochemical corrosion of carbon steel at the rate of 3.25 x 10^-5 A/cm² in water was examined under the conditions present during an accidental pipe rupture at the Mihama nuclear power plant: liquid conductivity, 7.5 μS/cm; dissolved oxygen concentration, 5 ppb or less; pH 8.6∝9.3; ferrous ion concentration, 20 ppb or less; temperature, 142 C. The corrosion rate of iron in a micro-cell with a dissolved oxygen reduction cathode was estimated to be only 1/400 of the preceding rate. On the other hand, that in a micro-cell with a hydrogen ion reduction cathode was estimated to be as high as 1/10 of the preceding rate, that is, 3.25 x 10^-6 A/cm². Two important factors may have influenced the corrosion rate: the remarkable wall thinning, which must have been the direct cause of the rupture of the pipe, was located close to, and downstream from, an orifice; and, the water temperature was in the range at which carbon steel makes a transition from the active to the passive state. Taking these facts into consideration, it appears possible that micro-cells with different corrosion rates might be generated and integrated into a macro-cell, where the iron dissolution rate might be accelerated to as much as 10 times that of the micro-cell. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] Short note. 2 figs.; 1 tab

[en] Correlations between ultraviolet extinction and visual polarization are studied. No correlations are found for 272 sampled stars. UV extinction and visual polarization are quite independent phenomena

[en] Isotope dilution analysis (IDA) has been historically used in situations where separation of an analyte from its matrix is difficult or imprecise. A requirement of IDA is that analyte mass be either measured or inferred for the determination of specific activity or its equivalent. Thus, two measurements are necessary: one of activity and one of mass, and the latter requirement frequently limits the sensitivity potentially available from IDA. Methods to circumvent the problem have been described, but these are usually subject to other constraints. For example, in substoichiometric IDA, equal amounts of analyte are isolated and counted before and after dilution, but the isolation of exactly equal quantities of material is usually difficult. This paper describes the principle of a new technique that couples IDA with carbon 14 to high-performance liquid chromatography (HPLC). It removes the need for a direct mass measurement and thereby greatly improves the sensitivity of IDA while retaining its high selectivity. Viewed from the chromatographic perspective, it offers a sensitive, analyte-specific procedure for indirect detection

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[en] Radioiodine is one of the most important radionuclides released by the accidents of Fukushima Dai-ichi nuclear power plant (FDNPP). Iodine-131 elevated ambient radiation dose rate immediately after the accident, but it is extinguished due to its short half-life. The long-lived 129I can be used as a tracer to retrospectively infer the level of 131I. Understanding of environmental behavior of 129I is important for preparedness against nuclear disaster. This study presents sampling campaigns on the Abukuma River during two high flow events, and discusses riverine 129I behavior based on comparisons with that of 137Cs. The study site was the Kuroiwa site locating at midstream of the Abukuma river. Its catchment area was 2886 km2 and mean 129I inventory in the catchment was 0.041 Bq m-2. Five and seven river water samples were taken during high-flow events in July 2018 (JUL18) and October 2018 (OCT18), respectively. Suspended sediment and filtrate samples were obtained by decantation and subsequent filtration with 0.45 μm-mash membrane filter, respectively. The suspended sediment and filtrate samples were measured for 137Cs activity concentrations with HPGe detector and then measured for 129I/127I ratio with accelerator mass spectrometer and for 127I concentration with ICP-QQQ-MS. Mean 129I activity concentration in suspended sediment during JUL18 and OCT18 were 1.0 and 0.43 mBq kg-1, respectively. In terms of temporal trends, 129I activity concentration in suspended sediment lowered in the peak water discharge phase, contrastive to those of 137Cs which were the highest at peak water discharge phase. Mean dissolved 129I activity concentrations during JUL18 and OCT18 were 0.18 and 0.067 μBq L-1, respectively. Both 129I and 137Cs activity concentrations in dissolved form tended to decrease with time during two high-flow events. Mean apparent distribution coefficient (Kd) during JUL18 and OCT18 were 4.3 ×104 and 6.1 ×103 L kg-1, respectively. The Kd values of 129I were lower than those of 137Cs and it reveal relatively-high solubility of 129I. Total exportation of 129I from the catchment during JUL18 and OCT18 were estimated as 1.0 × 104 and 2.3 × 104 Bq, respectively. Exported 129I in dissolved form accounted for 80 and 27% of total exportations, respectively. By contrast, more than 95% of 137Cs was exported in particulate form in the events. These results indicated an importance of dissolved form for understanding environmental behavior of radioiodine.

[en] Cu-NQR spectra were measured in La_2-x-yM_ySr_xCuO₄, (M=Nd, Gd, Eu, Pr and Y), and La_2-xBa_xCuO₄ with x=1/8. The low temperature tetragonal (LTT) structure is stabilized below T_d2 in all the samples other than M=Pr. The usual NQR spectra observed in T>T_d2 in all the samples change to abnormally broad ones after a complete wipeout of NQR signal below T_d2 except for the cases of M=Nd, Gd and Pr. In the cases of M=Nd and Gd, the complete wipeout continues to 1.5 K probably due to the extrinsic nuclear relaxation path through the paramagnetic fluctuation of Nd and Gd moment. In the case of M=Pr with no LTT phase, usual NQR spectrum continues to 1.5 K. These results support a pinning model for the static stripe ordering in the LTT phase

[en] In JAERI, PARC process based on Purex technique has been studied to as the basis of future reprocessing. The key of concept is to obtain the products, U and Pu, within only a single extraction cycle by separating Np and Tc from U and Pu before U/Pu partition. Two flow-sheet tests on the process were performed with 44 GWd/t PWR spent-fuel solutions. It was demonstrated that remaining Np in raffinate from co-extraction could be decreased to 13 % compared to the dissolver solution with increased solvent flow rate and with increased nitric acid concentration of FP scrubbing solution. It was demonstrated that Np separation (selective reduction by n-butyr-aldehyde) efficiency could be improved from 36 % to 78 % by flow-sheet modification; increasing reductant concentration and scrubbing solution flow rate. The feasibility of the Tc separation technique by high acid scrubbing was demonstrated. (authors)