[in Japanese]

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This report presents the activities of the Japanese Nuclear Data Committee (JNDC) in the period of April 1995 to March 1997. In this period, the various benchmark tests have been done for the JENDL-3.2 library released in 1994, and some problems inherited in the library have been pointed out and discussed in order to improve the library. On the other hand the special purpose files have been steadily progressed. In this report, the activities of each group under the committee are presented and JENDL-3.3, activation cross section file, high energy nuclear data file, nuclear data for evaluation of radiation damage and one group cross sections for ORIGEN2 code are also presented as topics of the activities.

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While the nuclear developed countries has been establishing the nuclear liability regime in the form of national law and international treaty, establishment of the nuclear liability regime in the developing countries which try to actively promote nuclear deveolpment is desired.
In the Asian area in which a large-scale nuclear development is expected in the future, China which has already started nuclear development showed a basic policy of nuclear liability regime in the form of “reply” instead of establishing a legal framework, and Indonesia which will start a nuclear development in the future has made a high-level legal framework covering nuclear liability regime.
To develop nuclear liability regime in the developing countries it is important to give consideration to establishment of national law in each country, increase in amount of liability and international cooperation and linkage in the area.

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The rates of hydrogen release from simulated high-level liquid waste (SHLLW) during irradiation of ⁶⁰Co γ-rays have been studied using a laboratory-scale apparatus. The SHLLW used was made up of 28 different metal elements, the concentrations of which were determined from a computed data (ORIGEN-2) for a Purex spent fuel (burn-up of 4.5GWd/t, cooling time of 4 years) except for those of corrosion products (Fe, Cr and Ni) and of chemical process additive (P). The nitrate ion concentration of the SHLLW was 4.97M.
The G-value of hydrogen release was 0.0164 for stirred conditions, but for nonstirred conditions with dose rate: 2.8kGy/h and with the SHLLW solution height more than 8cm, the following relation was found between the G-value and the solution height (dcm);
G(H₂)=0.100d^-1.6
The G-values of oxygen and nitrogen releases were also determined.

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In consideration of application for reprocessing facility, where a variety of causal events such as equipment failure and human error might occur, and the event progression would take place with relatively substantial time delay before getting to the accident stage, a component Monte Carlo program for accident sequence analysis has been developed to pursue chronologically the probabilistic behavior of each component failure and repair in an exact manner. In comparison with analytical formulation and its calculated results, this Monte Carlo technique is shown to predict a reasonable result. Then, taking an example for a sample problem from a German reprocessing facility model, an accident sequence of red-oil explosion in a plutonium evaporator is analyzed to give a comprehensive interpretation about statistic variation range and computer time elapsed for random walk history calculations. Furthermore, to discuss about its applicability for the practical case of plant system with complex component constitution, a possibility of drastic speed-up of computation is shown by parallelization of the computer program.

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The periodical inspection of nuclear power plants needs a lot of workforces with a high degree of technical skill for the maintenance of various sorts of machines. Therefore, a new type of maintenance training system is required, where trainees can get training safely, easily and effectively. In this study we developed a training simulation system for disassembling a check valve in virtual environment (VE).
The features of this system are as follows:
Firstly, the trainees can execute tasks even in wrong order, and can experience the resultant conditions. In order to realize this environment, we developed a new Petri-net model for representing the objects' states in VE. This Petri-net model has several original characteristics, which make it easier to manage the change of the objects' states. Furthermore, we made a support system for constructing the Petri-net model of machine-disassembling training, because the Petri-net model is apt to become of large size. The effectiveness of this support system is shown through the system development.
Secondly, this system can perform appropriate tasks to be done next in VE whenever the trainee wants even after some mistakes have been made. The effectiveness of this function has also been confirmed by experiments.

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