Development and Future Challenge for Advanced Solution Measurement and Monitoring System (ASMS)

JNFL and JAEA are collaboratively developing an Advanced Solution Measurement and monitoring System (ASMS) that is direct Pu measurement NDA system in the large scale solution tank containing purified plutonium nitrate for the improvement of current safeguards subjects to be solved, and for next generation safeguards instrument (NGSI). The demonstration type of ASMS was already installed and tested at PCDF. In the last INMM meeting, we presented that the ASMS has excellent monitoring capabilities to understand operation status and Pu amount change as a real time base. The ASMS consists of simple 3 He neutron detectors (~1% of counting efficiency) and a data acquisition system. In order to determine 240 Pu-eff. mass, neutron coincidence counting technique with known-alpha is applied. The essential of ASMS is to correct multiplication effect related to the Pu concentration change properly, that is, a challenge to apply known-alpha technique to the measurement of a large amount of solution because determination process of alpha and rho-zero is quite different from the technique applied to MOX powder. In order to establish quantitative measurement, accurate MCNPX modeling and calculations are very important and necessary. After calibration exercise implementation, we successfully obtained calibration constants (slope), and the total measurement uncertainty was approximately 3.4% for 240 Pu effective mass for 2 hours measurement except for the low level region. In this report, we summarize the first step results of ASMS development regarding quantitative measurement methodology. In addition, the image of safeguards by design and collaboration of SMMS are also presented