| 摘要 |
PURPOSE:To easily and exactly measure an effective multiplication constant by adding corrections until the attenuation constants of a 1st step and a 2nd step coincide with each other and determining the effective multiplication constant which is not disposed with an external neutron source by using the corrected group constants. CONSTITUTION:The attenuation constant 14 by measurement and the attenuation constant 15 by calculation are determined as the external neutron source is introduced. The distribution shape of the multiplying neutron flux is given as exp(-gamma.chi) if there is more than the specified distance from the external neutron source. In the formula, chi is the distance and gamma is the attenuation constant. gamma<2> has a close relation with the effective multiplication constant Keff of the system and gamma is nearly unequivocally determined in the system of the uniform compsn. but is not unequivocally determined in the system of the deep uncritical degree where the compsn. changes and, therefore, the constant 14 corresponding to the measuring position of the constant 15 is determined by calculation and both are compared. The effective multiplication constant Kj18 is determined by executing a three-dimensional intrinsic value mode calculation 17 when the constants 14 and 15 coincide with each other. On the other hand, the gammavalues are made to coincide with each other while the group constants 6 are corrected if the coincidence of the constants 14 and 15 is poor. The multiplication constant Kj18 corresponding to the respective charge steps of the irradiation fuel system is thereby determined. |
