[en] The number of times for setting up a control rod blocking monitor of a BWR type power plant is remarkably reduced to mitigate operator's burden. In the control rod blocking monitor, trip levels, as a judging standard upon outputting control rod blocking inhibition signals, are set up stepwise depending on the power level around control rods put to blocking control. The present invention comprises an allowance judging means capable of setting up trip levels for each of power levels corresponding to a plurality of control rods at once if the power levels are within the set up allowable range. With such a constitution, the set up allowable range is determined previously in the allowance judging means. Accordingly, when a gang blocking is conducted to control rods, if power levels around the control rods are increased at once into the set up allowable range, the trip levels for each of the control rods are set up at once. (I.S.)

[en] The present invention concerns a nuclear reactor instrumentation power monitor that can be used in, for example, BWR type nuclear power plants. Signals from multi-channel detectors disposed on field units are converted respectively by LPRM signal circuits. Then, the converted signals are further converted by a multiplexer into digital signals and transmitted as serial data to a central monitor unit. The thus transmitted serial data are converted into parallel data in the signal processing section of the central monitor unit. Then, LPRM signals are taken out from each of channel detectors to conduct mathematical processing such as trip judgment or averaging. Accordingly, the field unit and the central monitor unit can be connected by way of only one data transmission cable thereby enabling to reduce the number of cables. Further, since the data are transmitted on digital form, it less undergoes effect of noises. (I.S.)

[en] In an power region monitor for a reactor nuclear instrumentation system comprising local power region monitor (LPRM) units, average power region monitor (APRM) units and a rod block monitor (RBM) unit, each of the local power detected by each of LPRM units is inputted into the APRM units and the RBM unit in parallel. As a result, since each of the local power used when the RBM unit determines control rod withdrawal inhibiting signals is rapidly transmitted from each of the LPRM units to the RBM unit, a response time period from the detection of the local power in the reactor to the output of the control rod withdrawal signals can be shortened, thereby enabling to improve reactor safety. (N.H.)

[en] Non-equilibrium solute grain boundary segregation, a model for which was proposed by Xu, is discussed with particular focus on the influences of atomic diffusion and microstructure on grain boundary segregation

[en] Heretofore, since response time from the detection of the state in a reactor by a neutron monitor to the operation of a control rod withdrawal inhibiting monitor based on the detection data depends on the processing time of an average power region monitor, there has been a posibility that the response time is increased. Then, in the present invention, the result of the calculating operation of a local power monitor is directly inputted to the average power region monitor and the control rod withdrawal inhibiting monitor. In the average power region monitor, an averaging calculation is conducted to judge the output of scram signals and the result of the calculation is inputted to the control rod withdrawall inhibiting monitor. In the control withdrawal inhibiting monitor, the output of the control rod withdrawal inhibiting signal is judged based on the result of the calculation sent from the local power monitor and a processing signal in the average power region moitor. In view of the above, the control rod with drawal inhibiting signal can be judged without waiting the judgement for the output of the scram signals, thereby enabling to improve the response speed remarkably. (N.H.)

[en] In this research fractography of high-purity iron cleaved at low temperatures (4.2 K) is investigated to clarify fundamental processes without the influence of impurities and inclusions. Factors affecting the initiation and the propagation of cracks are discussed from observation of river patterns and twin traces, and it is pointed out that intersection of a deformation twin with an interface such as other twins, grain boundaries or the surface can play an important role in the initiation and the propagation of cracks. (orig./MM)

[en] Surface analysis methods, such as Auger electron spectroscopy, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, glow discharge optical emission spectrometry and so on, have become indispensable to characterize surface and interface of many kinds of steel. Although a number of studies on characterization of steel by these methods have been carried out, several problems still remain in quantification and depth profiling. Nevertheless, the methods have provided essential information on the concentration and chemical state of elements at the surface and interface. Recent results on characterization of oxide layers, coated films, etc. on the surface of steel are reviewed here. (author). 99 refs

[en] The solubility limit of iron-phosphide in ferritic iron was examined with electrical resistivity measurements by using the relationship between resistivity and the amount of dissolved phosphorous. The temperature dependence of the solubility obtained was in good agreement with previous results. The kinetics of precipitation of the phosphide from a supersaturated Fe-3.75 at.% P alloy was also investigated with changes of the resistivity by isochronal and isothermal annealing. The activation energy for the precipitation process of the phosphide was about 2.6 eV. Diffusivities of phosphorus were estimated from the annealing behaviour and the morphology of the precipitates, which were comparable to those obtained with the tracer method previously. This suggests that the precipitation process of phosphide is rate controlled by diffusion of phosphorus in ferritic iron-phosphorus alloys. (orig.)

No abstract available

[en] Ruthenium is adsorbed on activated carbon impregnated with 2,4,6-tri-2-pyridyl-1,3,5-triazine (TPTZ-AC). A simple and rapid determination method for trace amounts of Ru by graphite furnace AAS using direct heating of Ru adsorbed TPTZ-AC was investigated. The proposed method is as follows. A sample solution of 100-1000 cm³ containing Ru is mixed with 50 mg of TPTZ-AC. The pH is then adjusted to 7.0 with phosphate buffer solution, and stirred for 10 min. The Ru adsorbed TPTZ-AC was separated from the sample solution by filtration. The TPTZ-AC on membrane filter is dispersed in 5.0 cm³ water. After shaking, 10 μl of the resulting suspension is injected directly into the graphite furnace. The absorbance is measured at 349.9 nm. The pyrocarbon treated graphite tube was most effective for the measurement of Ru. The calibration curve was liner below 2.5 μg/100 cm³ (aqueous phase). The determination limits (3σ) were 0.08 μg/100 cm³ (aqueous phase). The presence of such as Cu, Ni did not interfere. Interference by Fe could be masked by adding thiourea and 1,10-phenanthroline and ammonium fluoride. The proposed method was applied to the determination of Ru in several water samples. (author)