Results of irradiation experiment on the degradation of ductility of 8-9Cr reduced activation ferritic/martensitic steels are introduced, including those of irradiated austenitic steels. M acroscopic models of post irradiation tensile and fatigue properties obtained from the results are shown. Concept of the models should be essential for future design criteria development....
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Ductility loss of materials by neutron irradiation and structural integrity of reactor core

The Tokai Reprocessing Plant (TRP) is developing the technology to recover uranium and plutonium from spent nuclear fuel. There is an analytical laboratory which was built in 1977, as one of the most important facilities for process and material control analyses at the TRP. Samples taken from each process are a nalyzed by various analytical methods using hot cells, glove boxes and hume-hoods. A large number of maintenance work have been so far carried out and diffe rent types of experience have been accum...
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Maintenance experiences at analytical laboratory at the Tokai Reprocessing Plant

The ductile-brittle transition behavior of neutron-irradiated welded A533B Cl.1 steel has been studied by means of small specimen test technique for discussing the specime n size effects on the impact properties. Standard size, one-third size and 1.5mm size Charpy V-notch specimens were prepared. Neutron irradiation was performed in JMTR wit h fluencies up to 0.75 and 1.3 X 1024 n/m°(E>1 MeV). Normalization of the USE is done by a curve fitting method and the USE of different size of specimens can be expre...
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Evaluation Technique of Neutron-Irradiation Embrittlement in Welded RPV

In the decommissioning measures of Fukushima Daiichi Nuclear Power plant (1F), it is important to ensure the thermal stability of the reactor and the whole system by the cooling system in order to prevent criticality of fuel and fuel debris. However, wall thinning is concerned due to the corrosion in the piping of the cooling system. In order to maintain the safety of the system, it is necessary to manage the piping thinning. In this study, the EMAT thickness monitoring system, which can measure thickne...
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Application of monitoring system using electromagnetic acoustic transducers for wall thickness measurement to Fukushima Daiichi nuclear power plant Unit 4 spent fuel pool cooling piping

In this study, we propose a novel EMAT-ECT multi sensor aiming at advanced structural health monitoring. For the purpose, proto-type EMAT-ECT multi-sensor was developed and their functions both as ECT and EMAT prove were evaluated. Experimental results of pulse ECT using the EMAT-ECT multi-sensor showed that the pr oposed sensor has a capability of detection and sizing of flaws. Experimental results of EMAT evaluation using the EMAT-ECT multi-sensor showed that ultrasoni c wave was transmitted by EMAT-ECT ...
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Development of novel EMAT-ECT multi-sensor and verification of its feasibility

The degradation of 1-nozzle type Jet Pump (JP) efficiency by crud deposition has been recognized in some BWRs. In order to remove crud, we must clean each o r all of JP inner surface. The increase in cleaning surface area induces the increase in outage period and cost, therefore, in the previous study we looked for the most effective cleaning portion at inner surface for efficiency recovery. In this study, for the 5-nozzle type JP, we evaluated the effect of crud portion on decrease in efficiency of 5-noz...
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Studies on Recovering Method of 5-nozzle type Jet Pump Efficiency