Katsutoshi Watanabe

Capability of energy selective neutron irradiation test facility (ESNIT) for fusion reactor materials testing and the status of ESNIT program

Abstract The concept of a high energy neutron irradiation facility named Energy Selective Neutron Irradiation Test Facility (ESNIT) was conceived at Japan Atomic Energy Research Institute (JAERI) as a facility for materials research in generic nuclear applications for which major potential research incentives were originated from nuclear fusion application. Technological survey and feasibility studies of ESNIT have continued since 1988 and two international workshops have been held in 1989 and 1991. In this paper, the capability of ESNIT for fusion reactor materials testing and the status of technological survey activities including deuteron accelerator system, target system and experimental system are summarized.

Characteristics of an energy selective neutron irradiation test facility (ESNIT) for material irradiation studies

Abstract The concept of an energy selective neutron irradiation test facility (ESNIT) was generated at the Japan Atomic Energy Research Institute, and a program for the preliminary technical survey was initiated in 1988. The potential benefit of such a facility is that it makes possible that neutron-irradiation experiments on materials can be carried out with well-defined energy spectra up to reasonably high flux and fluence levels and with high manipulability. A significant fraction of its applications will be focused on fundamental aspects of radiation damage in fusion reactor materials.

Postirradiation Tensile and Creep Properties of Heat-Resistant Alloys

The effect of neutron irradiation on hightemperature tensile and creep properties of austenitic heat-resistant alloys was studied. The effect, which appeared in the loss of ductility at elevated te...

Development of a filler metal for Hastelloy alloy XR weldment

Abstract The weldability and high temperature strength properties of tungsten-inert-gas (TIG) weldments of Hastelloy alloy XR were investigated by using two different heats of filler metals; the first (HXRF1) was designed on the basis of multiple regression analysis; the second (HXRF2) was the reference material. Bend tests, the FISCO cracking test and optical metallography were used to evaluate weldability. Tensile and creep tests were performed at 900 °C to evaluate high temperature strength properties. The results of weldability tests for both alloys showed good performance. The tensile properties of the weldments were remarkably improved in particular with respect to high temperature ductility. The creep rupture strength in the weldments made with alloy-designed HXRF1 was much higher than those of the Hastelloy alloy XR-II base metal with a higher B content. Furthermore, the creep properties were stable with respect to variations in welding conditions. Since the values of creep rupture time predicted from the regression equation for the weldment made with alloy HXRF1 filler metal were in close agreement with those experimentally determined, it was concluded that the proposed alloy design methodology was valid and useful for filler metal development.

Present status of ESNIT (energy selective neutron irradiation test facility) program

Abstract The present status of technical studies of a high energy neutron irradiation facility, ESNIT (energy selective neutron irradiation test facility), is summarized. Technological survey and feasibility studies of ESNIT have continued since 1988. The results of technical studies of the accelerator, the target and the experimental systems in ESNIT program were reviewed by an International Advisory Committee in February 1993. Recommendations for future R&D on ESNIT program are also summarized in this paper.

Preliminary design study of the target and lithium circulation system for ESNIT

Abstract The preliminary design study of the target and lithium (Li) circulation system for ESNIT (Energy Selective Neutron Irradiation Test Facility) has been made, based on the Fusion Material Irradiation Test Facility (FMIT) design. It is important to estimate the difference between the Li temperature and its boiling point (boiling margin) as a function of Li flow rate and deuteron beam energy. A one dimensional finite element method has been used to analyze the boiling margin considering the parameters of beam energy. Li velocity, thickness of the Li flow stream and curvature of back wall of target container. For the Li circulation system, technological evaluations of the main Li circulation system and the Li purification system have been carried out. For all the impurity elements, including deuteron (D)Li reaction products such as beryllium (Be) and tritium (T), a sufficient low impurity level of about 10 ppm can be achieved by operating a cold trap, absorber and hot trap as the purification system.

DEVELOPMENT OF HASTELLOY ALLOY XR FILLER METAL DESIGNED BY MULTIPLE REGRESSION ANALYSIS

In order to develop the filler metal for Hastelloy Alloy XR, the weldability and high temperature strength properties of its weldment were investigated using the filler metals, which were alloy-designed on the basis of multiple regression analysis. It was found that the weld cracking susceptibility was able to be lowered by optimizing carbon and boron content in the filler metals without degrading the high temperature strength properties. The present alloy design method was verified to be valid from the comparatively good correspondence between the experimental results and ones predicted by multiple regression analysis.

EXPLORATORY STUDY ON PROVIDING AUSTENITIC STAINLESS STEELS DESIGNED FOR NUCLEAR APPLICATIONS

Application of an alloy design technique to the exploratory of new Fe-base austenitic alloys reached two types of potentially high performance materials. Addition of W and/or Mo with reduced Cr/Ni ratio yielded marginal strength and ductility with possibly enhanced resistance to the reactor environment degradation. Accuracy of design and prediction was improved in terms of creep-rupture strength and phase stability through a few series of confirmation tests.