Research Of Effective Neutron Multiplication Factor And Neutron Flux Distribution For Accelerator Driven Sub-Critical System On DF-3 Facility

The article gives research for some physics parameters of ADS sub-critical reactor with external neutron source by integrating experimental with theory analysis. The ADS sub-critical effective neutron multiplication factor and neutron flux distribution have been investigated on DF-3 facility, the effective neutron multiplication factor (keff ) was measured by extrapolate-period method and source jerk method, the sub-critical reactor effective neutron multiplication factor (ks) with external neutron source was measured by source neutron multiplication method, and the neutron flux distribution was measured by activation foil. In the theory analysis, the sub-critical effective neutron multiplication factor (ks) with external neutron source and the effective neutron multiplication factor (keff) was calculated respectively by using the normal source and critical source of MCNP code. The result is satisfied with experiment and calculation.This paper has six chapters. Chapter 1 is the introduction, describing the main purpose and applied prospect of this research, the principle, features and purpose of ADS. The main content of this research are also introduced, including experiments on DF-3 facility and using of MCNP calculation.Chapter 2 is the introduction on the histories and methods for the measurements of effective neutron multiplication factor and distribution of neutron flux, including the static methods and dynamic methods to measure the effective coefficient factor which has been used in critical facility in many countries, the current condition of measuring the sub-critical reactor effective neutron multiplication factor in foreign countries, the activation foil method and detector method to measure the neutron flux distribution. Compare with these methods, the experiment plans of measuring the effective coefficient factor and neutron flux distribution is given to the experiment on DF-3 facility.Chapter 3 is research on the physical characteristic parameters keff and ks ofsub-critical reactor. The effective neutron multiplication factor with or without external neutron source is investigated, the definitions and relation of reactor effective coefficient factor keff and ks has been made, keff is the characteristic parameter of reactor, determined by reactor itself, to show the safety of the reactor. ks is the sub-critical effective neutron multiplication factor with external neutron source, determined by reactor and the position and neutron spectrum, to show the using efficiency of external source. is defined to the ratio between the worth of external neutron and fission neutron.Chapter 4 is the introduction for the methods of the measurement and calculation. These methods would be used in this research work on DF-3 facility. For calculation, the treatment of Monte Carlo particle transfusion method and MCNP code, include the definition of keff, how to use MCNP code for keff and neutron flux calculation are introduced. For the experiment on DF-3 Facility, the extrapolate-period method and source jerk method are introduced to measure the keff and Source Neutron Multiplication Method is introduced to measure the ks. Finally, The way of how to measure the neutron flux distribution is made out.Chapter 5 is for giving out the experiment result on DF-3 facility and MCNP Calculation result, including keff. ks and neutron flux distribution. The results are also discussed.Chapter 6 is the research conclusion. According to the experiment and calculation result, some conclusions of this research are given. This is the first time to verify the following conclusion: The source jerk method give the effective coefficient factor of keff, and the source neutron multiplication method give the reactor effective coefficient factor ks which is effected by the source and position of source, these two result is different. The puzzle are solved, that is about the existed measurement difference between the methods of measuring the reactor effective neutron multiplication factor when consider these two result are the same definition. The re...