Sequential material balance evaluation by NRTA has many advantages for large-scale facilities, especially those handling plutonium.įrom the Safeguards and Security by Design (SSBD) standpoint, it is essential to conduct a preliminary performance evaluation of any NMA system, including NRTA, before construction of a facility. Whereas conventional NMA has relatively longer MBP, such as only a single material balance evaluation per year, NRTA performs sequential material balance evaluation for on-time detection of abrupt nuclear diversions. The main difference between conventional NMA and NRTA is the number of Material Balance Periods (MBPs). NRTA also has been considered as a primary safeguards method in pyroprocessing, and in fact efforts to achieve an optimal NRTA system for pyroprocessing are already underway. Notably, the Near Real Time Accountancy (NRTA) system based on NMA recently has been introduced at large-scale reprocessing facilities such as the Rokkasho Reprocessing Plant (RRP) for quantitative and timely detection goal for safeguards. NMA system is an important part in the safeguards field to quantitatively evaluate the material balance for nuclear materials such as uranium-235 and plutonium, which is referred to as Material Unaccounted For (MUF). Nuclear Material Accounting (NMA) is defined as “activities carried out to establish the quantities of nuclear material present within defined areas and the changes in those quantities within defined periods”.
#Tecdoc muf code
It is expected that this code will be a useful tool for evaluation of NRTA system of pyroprocessing and other reprocessing facilities. In the present work, some intercomparative studies were conducted to verify the M&S techniques applied in this code.
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Furthermore, a user can make a static process model having simplicity and a matching NMA model based on the PYMUS+ code regardless of facility throughput and is not even required to have professional programming knowledge. The most important feature of the PYMUS+ code is its capability to evaluate many process and NMA system model options that a user wants to evaluate. According to a previous report, the PYMUS code, the predecessor of PYMUS+, can calculate MUF uncertainties only for a fixed model having 10 tHM/year, whereas the PYMUS+ code can additionally calculate detection probabilities according to diverse nuclear diversion scenarios as well as MUF uncertainties. For these purposes, in the present study, the PYroprocessing Material flow and MUF Uncertainty Simulation+ (PYMUS+) code, which uses evaluation algorithms to calculate many safeguards factors such as MUF uncertainty, detection probability, and others, was developed. Modeling and Simulation (M&S) work is a good way to evaluate performance for various NMA systems and to determine the optimal one among different options. Such evaluation improves safeguards effectiveness and efficiency. It is also important to quantitatively evaluate the performance of NMA system including NRTA from the standpoints of Safeguards and Security by Design (SSBD) prior to construction of nuclear-material-handling facilities. It has become more important for large reprocessing facilities to apply Near Real Time Accountancy (NRTA) system based on NMA and statistical techniques to meet quantitative and timeliness goals. The low number of MUF in comparison with the SQ showed that the RDE has a high proliferation resistance.The Nuclear Material Accounting (NMA) system is one of the main safeguards measures to detect the existence of nuclear material diversion. The sets of instruments and measurements designed will give a comprehensive data of each nuclear material in the RDE. The result of total uncertainty and MUF calculation showed that the safeguards system and the material measurement designed for RDE is amendable. According to the number of MUF counted, it is impossible to reach 1 SQ if the diversion done is only by taking the advantage of MUF in the measurement. The number of MUF in each KMP according to total uncertainty showed a number below 1 kg of U-235 in one inventory period (~12 months). The total uncertainty from each KMP showed a number less than 10%. the approximate amount of nuclear material for which the possibility of manufacturing of a nuclear explosive device cannot be excluded). The effectiveness of the safeguards system is examined by comparing the resulting MUF with the number of SQ ( = significant quantity, i.e. Material unaccounted for (MUF) is calculated using the uncertainty of each method and instrument. Methods and instruments used for the RDE's nuclear material accounting and safeguards system are reviewed in this paper. A safeguards assessment for the 10-MWt RDE Experimental HTGR needs to be established in order to fulfill the requirements needed to construct it.
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