Cold nuclear fusion reaction

In this report, the problems in the research on cold nuclear fusion reaction as of December, 1990, particularly those in the measurement of neutron are described. Since the report of the success in normal temperature nuclear fusion reaction in March, 1989, many researchers and the large amount of money were poured into this research, but after one and a half years, the phenomena reported by Fleischmann and Pons at the beginning are almost denied. The method of detecting cold nuclear fusion reaction progressed steadily in the process of the research carried out so far, but the parameters which determine the reaction are unknown, and the reproducibility has not been able to be confirmed. As the method of verification, other methods than the detection of 2.45 MeV neutrons by highly reliable measurement of extremely minute amount cannot be considered. The evaluation of the influence of cosmic radiation and environmental radioactivity, the problems in the measurement of neutrons at extremely weak level and so on are described. It is desirable to standardize the reaction system and detection system and cross-check the affirmative results. (K.I.)