Nuclear Data Uncertainties On The Development Of The Ads System Keff And Other Integral Amount Of Impact And Wims82-group Library

This work concerns two studies. One is about the effects on sub-criticalsystem of ADS(Accelerator-Driven System) caused by the uncertainty fromnuclear data. The other is the generation of WIMS 82 group library for the"VENUS-I" sub-critical system which will be built at CIAE (China Instituteof Atomic Energy ) .1 The effects on sub-critical system of ADS caused by the uncertainty from nuclear dataIt' s well known that the uncertainty of the calculations for the nuclear engineering comes from not only codes and tools used in the calculation, but also the uncertainty from nuclear data. With the development of computer science and the widely application of Monte Carlo method etc, the errors aroused from computer and computational methods are no longer the main reason for the precision of calculation in nuclear engineering. The errors caused by the uncertainty from nuclear data become more important than the former.Differing from ordinary critical reactor the ADS runs under the sub-critical state from beginning to end. During its whole lifetime, the effective multiplication constant keff changes between 0.90 and 0.98. It' s significant to study the effects caused by the uncertainty from nuclear data on integral parameters such as keff etc. in sub-critical assembly.In this paper, Monte Carlo simulation method was used to study how integral parameters are affected by the uncertainty from nuclear data in sub-critical system. The work was also done to assess main contributors of all nuclides for the effects. The sensitivity of effective multiplication constant keff to nuclear data was stressed to study. The effects on reaction rate were also studied.Monte Carlo code MCNP4C was used in the study. The spectra of thespallation neutron used in the MCNP4C code were calculated by using MCNPX code. The source neutrons with energy above 20 MeV were cut off in MCNP4C calculations. The angular distribution of source neutrons was supposed to be isotropic in the target space. In the numerical simulation, the response of keff values was calculated when cross sections and double differential cross sections were changed respectively. Different perturbations methods were used for cross-sections, such as the perturbation of total cross-section for a certain nuclide in one material, the perturbation of a partial cross-section of a certain nuclide. In addition, the keff values and reaction rates were calculated based on different evaluated library, such as ENDF/B-VL 6, JENDL-3.2 or CENDL-3.0. And the impacts on the system were compared and analyzed.According to the studies, it is concluded that:I. In ADS, the effects on integral parameters caused by the uncertainty from nuclear data depend on the contents of nuclides. The nuclides contained in ADS which have larger quantity, such as Zr 239Pu Pb Bi, have greater sensitivity to keff than others.II. The effects on integral parameters caused by the uncertainty from nuclear data also depend on the location of the nuclides in ADS. Pb & Bi have negative response to keff when located in reactor core, but have positive response to keff when located in reflector.III. For the accelerator-driven transmutation of Waste (ATW), the impacts of different reaction cross-sections on the keff values are different. The sensitivity ( k/ k) to u value and fission cross-section for 239Pu are largest; The sensitivities to certain nuclides and cross-sections are rather large, such as the u value and fission cross-section for 241Pu & 240Pu, the elastic cross-section for Pb & 209Bi and the capture cross-section for 239Pu & 99Tc. So it is very important to select accurate evaluations for above nuclides.IV. The double differential spectra has great effect on the keff values in sub-critical system when Pb acts as reflector.V. Remarkable differences of calculated integral parameters on the ADS were observed based on different evaluated libraries. The difference of keff is about - HOOpcm caused by the different data of Am, 245Cm, 237Np from CENDL-3. 0, JENDL-3. 2 and ENDF/B-VI.VI. The spallation neutron source spectra...