Composition of reactor radiation—statistically significant radiation damage factor of diamond

1. A computer program implementing a stepwise procedure for analyzing multidimensional regressions has been perfected. Multidimensional regressions on a sample of sizen=15 was analyzed in order to find the best subset of independent variables for purposes of prediciting the radiation damage to diamond during irradiation in a reactor. Three functions with participation of the γ-ray flux density are also included in the model as regressors, in addition to the traditional fastneutron fluence and irradiation temperature. It was established that a collection of three conditions of irradiation gives the best predictions: fast-neutron fluence, irradiation temperature, and radiation composition factor. 2. It was shown that the effectiveness of the irradiation temperature, fast-neutron fluence, and radiation composition factor at the center of the array of independent variables is in the ratio 0.7, 0.35, and 0.617. In conclusion, it should be noted that the concrete results of statistical analysis of radiation damage to diamond, confirming the significant effect of the radiation composition factor, are also of interest for predicting the state of the materials of the reactor vessel on the basis of data obtained in research reactors and for samples of nuclear power plants and samples cut fromtemplates and trepans of real vessels. Up to now attempts at statistical analysis of data on these materials, as a rule, led to unsatisfactory results. It was shown only that there are some factors which were not taken into account, neglecting which can lead to unjustifiably optimistic conclusions. The established fact that the effect of radiation γ-annealing is also observed in vessel materials [7] is a sufficient basis for performing investigations similar to the one described in the present paper.[PUBLICATION ABSTRACT]