Title: FFTF PIPE CHASE STREAMING EXPERIMENT.

A second ORNL Tower Shielding Facility experiment has been performed and analyzed in the investigation of techniques for predicting the extent of neutron streaming through the sodium coolant pipes of the Fast Flux Test Facility (FFTF). Measurements of neutron intensities were made with Bonner ball detectors, and neutron spectra were measured with a Benjamin spectrometer. The analysis consisted of calculations of the Bonner ball and spectrometer responses with the two-dimensional discrete ordinates code DOT-III using 50-group and 14-group cross-section sets and assumptions of both isotropic and anisotropic boundary sources at the pipe-chase entrance. The Monte Carlo codes AMC and MORSEmore » were used to correct the DOT calculations for three-dimensional geometric effects inherent in the experiment. For points inside the plenum, the calculated and experimental Bonner ball responses are in exceptionally good agreement; for points outside the plenum the calculated responses are approximately 20% higher than the experimental results. The calculated and measured neutron spectra agree at all three locations. It is concluded that the same calculational approach would accurately predict, or possibly slightly overpredict, the neutron flux levels that will exist in the heat exchanger vaults of the FFTF.« less

The experimental program performed in the SRE auxiliary and main primary galleries was part of a program to determine the adequacy of the shielding configuration for the SRE. The work discussed in this report is concerned with analysis of neutron streaming at coolant pipe penetrations of the reactor vessel, analysis of the shielding required, testing and evaluation of recommended shielding, and measurement and correlation of neutron streaming in labyrinths with theory. The activation analysis method using zinc sheets which was developed for the program of determining thermal neutron streaming in the SRE primary galleries was proven to be versatile, accurate,more » and reliable. A modified form of the theoretical method of Price, Horton, and Spinney, used to determine neutron scattring through labyrinths, was found to agree favorably with the experimental results obtained from the SRE primary galleries. The theoretical attenuation method used no determine the neutron shield configuration installed in the auxiliary primary gallery was found to give an overestimate of the actual attenuation properties of this shield. The neutron shield configuration installed in the auxiliary primary gallery proved to be adequate in reducing the thermal neutron streaming flux to an acceptable level. It is concluded that both SRE primary galleries are now adequately shielded to prevent excessive neutron- induced activation of the components and equipment located therein. (auth)« less

This report summarizes the calculational results from analyses of a Clinch River Breeder Reactor (CRBR) prototypic coolant pipe chaseway neutron streaming experiment Comparisons of calculated and measured results are presented, major emphasis being placed on results at bends in the chaseway. Calculations were performed with three three-dimensional radiation transport codes: the discrete ordinates code TORT and the Monte Carlo code MORSE, both developed by the Oak Ridge National Laboratory (ORNL), and the discrete ordinates code ENSEMBLE, developed by Japan. The calculated results from the three codes are compared (1) with previously-calculated DOT3.5 two-dimensional results, (2) among themselves, and (3) withmore » measured results. Calculations with TORT used both the weighted-difference and nodal methods. Only the weighted-difference method was used in ENSEMBLE. When the calculated results were compared to measured results, it was found that calculation-to-experiment (C/E) ratios were good in the regions of the chaseway where two-dimensional modeling might be difficult and where there were no significant discrete ordinates ray effects. Excellent agreement was observed for responses dominated by thermal neutron contributions. MORSE-calculated results and comparisons are described also, and detailed results are presented in an appendix.« less