JASPER Experimental data Book (IX); Axial shield re-measurement experiment

not registered; Takemura, Morio*

This report is intended to make it easier to apply the measured data obtained from the Axial Shield Re-Measurement Experiment, which was conducted at the Oak Ridge National Laboratory(ORNL) during about one month beginning at the start of August, 1992 as the last one of a series of experiments planned for the Japanese-American Shielding Program for Experimental Research (JASPER) which was started in 1986. For this reason, the information presented includes specifications and measurement data for all configurations, compositions of all materials, characteristics of the measurement system, and daily-basis records of measurements. Axial Shield Experiment was performed in 1990, to study the neutron attenuation characteristics of the axial shield of liquid metal fast reactor (LMR) which is designed in the fuel assembly to reduce the neutron fluence in regions above the core. However, the investigation of the experimental results showed the capability of the influence to the streaming characteristics by the scattered neutrons from the concrete region surrounding the mockup of axial shield region. So, the Axial Shield Re-Measurement Experiment was newly planned and performed, in which the concrete region was covered by lithium-paraffin layer at the front surface. A spectrum modifier was placed behind the TSR-II reactor of Tower Shielding Facility to mockup the leakage neutron spectrum typical to LMRs. Neutron flux was measured behind the experimental configurations with various types of detectors. Information presented in this report is based mainly on a report issued by ORNL (ORNL/TM-12276, "Measurements for the JASPER Program Axial Shield Re-Measurement Experiment") Additional information reported by the assignee is utilized also.