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JAEA Reports

Final report on feasibility study of Pu monitoring and solution measurement of high active liquid waste containing fission product at Reprocessing Facility

Sekine, Megumi; Matsuki, Takuya; Suzuki, Satoshi*; Tsutagi, Koichi; Nishida, Naoki; Kitao, Takahiko; Tomikawa, Hirofumi; Nakamura, Hironobu; LaFleur, A.*; Browne, M.*

JAEA-Technology 2019-023, 160 Pages, 2020/03

JAEA-Technology-2019-023.pdf:9.43MB

The International Atomic Energy Agency (IAEA) has proposed in its Research and Development plan (STR-385), the development of technology to enable real-time flow measurement of nuclear material as a part of an advanced approach to effective and efficient safeguards for reprocessing facilities. To address this, Japan Atomic Energy Agency (JAEA) has been tackling development of a new detector to enable monitoring of Pu in solutions with numerous FPs as a joint research program with U.S. DOE to cover whole reprocessing process. In this study, High Active Liquid Waste (HALW) Storage Facility in Tokai Reprocessing Plant was used as the test field. At first, the design information of HALW storage tank and radiation (type and intensity) were investigated to develop a Monte Carlo N-Particle Transport Code (MCNP) model. And then, dose rate distribution outside/ inside of the concrete cell where the HALW tank is located was measured to design new detectors and check MCNP model applicability. Using the newly designed detectors, gamma rays and neutron were continuously measured at the outside/ inside of the concrete cell to assess the radiation characteristics and to optimize detector position. Finally, the applicability for Pu monitoring technology was evaluated based on the simulation results and gamma-ray/neutron measurement results. We have found that there is possibility to monitor the change of Pu amount in solution by combination both of gamma-ray and neutron measurement. The results of this study suggested the applicability and capability of the Pu motoring to enhance safeguards for entire reprocessing facility which handles Pu with FP as a feasibility study. This is final report of this project.

Journal Articles

Feasibility study result of advanced solution measurement and monitoring technology for reprocessing facility

Sekine, Megumi; Matsuki, Takuya; Suzuki, Satoshi*; Tsutagi, Koichi; Tomikawa, Hirofumi; Nakamura, Hironobu; LaFleur, A.*; Browne, M.*

Proceeding IAEA Symposium on International Safeguards; Building Future Safeguards Capabilities (Internet), 8 Pages, 2018/11

The IAEA has proposed, in its Research and Development plan (STR-385), the development of technology to enable real-time flow measurement of nuclear material as part of an advanced approach to effective and efficient safeguards for reprocessing facilities. To address this, JAEA and JNFL had previously designed and developed a neutron coincidence based non-destructive assay system to monitor Pu in solution directly after a purification process. To enhance this technology for entire reprocessing facilities, as a feasibility study, JAEA has been tackling development of a new detector to enable monitoring of Pu in solutions with numerous fission products (FPs) as a joint research program with the U.S. DOE. In this study, the High Active Liquid Waste (HALW) Storage Facility in Tokai Reprocessing Plant (TRP) was used as the test bed. The design information of the HALW storage tank and radiation (type and intensity) were investigated, to develop a Monte Carlo N-Particle Transport Code (MCNP) model. Then, dose rate distribution inside the concrete cell where the HALW tank is located was measured, to enable design of new detectors and check the integrity of the MCNP model and its applicability. Using the newly-designed detectors, $$gamma$$-rays and neutrons could be measured continuously at the outside/inside of the concrete cell, to optimize detector position and the radiation characteristics. The applicability as a Pu-monitoring technology was evaluated, based on the simulation results and $$gamma$$-ray/neutron measurement results. We have found that there is a possibility to monitor the change of Pu amount in solution by combination of $$gamma$$-ray and neutron measurements. The results of this study suggest a feasibility study into the applicability and capability of Pu monitoring to enhance the entire reprocessing facility handling Pu with FPs. In this paper, a summary of the project will be presented.

Journal Articles

Feasibility study of advanced measurement technology for solution monitoring at reprocessing plant; Dose rate measurement for the solution including Pu with FP

Matsuki, Takuya; Yamanaka, Atsushi; Sekine, Megumi; Suzuki, Satoshi*; Yasuda, Takeshi; Tsutagi, Koichi; Tomikawa, Hirofumi; Nakamura, Hironobu; LaFleur, A. M.*; Browne, M. C.*

Proceedings of INMM 58th Annual Meeting (Internet), 8 Pages, 2017/07

The Tokai Reprocessing Plant (TRP) has been developing a new detector from 2015 to 2017 for purpose to monitor Pu amount in High Active Liquid Waste (HALW) containing FP. It can make a contribution to an advanced approach to effectively and efficiently conduct safeguards for reprocessing facilities because it becomes available to monitor and verify nuclear material movement continuously by a new detector, which has proposed by IAEA. For the second step of this project, we conducted dose rate measurement on the guide rail installing in the cell storing the HALW tank and comparison between measured dose rate distribution and calculation result by MCNP simulation in order to investigate the dose rate distribution which is needed for shielding design of a new detector that is used for radiation (neutron/$$gamma$$ spectrum) measurement in the cell and inquest on the monitoring position of the detector for Pu monitoring. In this paper, we report the result of the dose rate measurement in the cell, improvement of the simulation model which is cleared by comparison between measurement result and calculation result and our future plan.

Journal Articles

Development and implementation of GloveBox Cleanout Assistance Tool (BCAT) to detect the presence of MOX by computational approach

Nakamura, Hironobu; Nakamichi, Hideo; Mukai, Yasunobu; Hosoma, Takashi; Kurita, Tsutomu; LaFleur, A. M.*

Proceedings of International Conference on Mathematics & Computational Methods Applied to Nuclear Science & Engineering (M&C 2017) (USB Flash Drive), 7 Pages, 2017/04

In order to maintain facility nuclear material accountancy (NMA) and safeguards properly, to understand where and how much holdup deposit in the process is presence is very important for the cleanout before PIT. JAEA and LANL developed a GloveBox Cleanout Assistance Tool (BCAT) to help cleanout (MOX powder recovering in a glovebox) for invisible holdup effectively by computational approach which is called distributed source-term approach (DSTA). The BCAT tool is a simple neutron measurement slab detectors and helps operator to find locations of holdup. To know the holdup location and the activity from the neutron measurements, the relation between BCAT measurements results at predetermined positions (57 positions) and source voxels (53 voxels) that we want to know the holdup activity was mathematically defined as a matrix by the MCNPX simulation. The model of MCNPX for entire process is very precisely established. We have implemented and experimentally proved that the BCAT tool can direct the operator to recoverable holdup that would otherwise be accounted for as MUF. Reducing facility MUF results in a direct improvement of the facility NMA. The BCAT enables the staff to significantly improve their knowledge of the locations of residual holdup in the process area. JAEA would like to use this application for dismantling of the glovebox with transparency in the future.

Journal Articles

Feasibility study of advanced technology for Pu with FP solution monitoring; Overview of research plan and modelling for simulation

Sekine, Megumi; Matsuki, Takuya; Suzuki, Satoshi; Tanigawa, Masafumi; Yasuda, Takeshi; Yamanaka, Atsushi; Tsutagi, Koichi; Nakamura, Hironobu; Tomikawa, Hirofumi; LaFleur, A. M.*; et al.

EUR-28795-EN (Internet), p.788 - 796, 2017/00

The IAEA has proposed in its long-term R&D plan, the development of technology to enable real-time flow measurement of nuclear material as a part of an advanced approach to effective and efficient safeguards for reprocessing facilities. To address this, JAEA has designed and developed a neutron coincidence based nondestructive assay system to monitor Pu directly in solutions which is after purification process and contains very little fission products (FPs). A new detector to enable monitoring of Pu in solutions with numerous FPs is being developed as a joint research program with U.S. DOE at the High Active Liquid Waste (HALW) Storage Facility in Tokai Reprocessing Plant. As the first step, the design information of HALW tank was investigated and samples of HALW was taken and analyzed for Pu concentration and isotope composition, density, content of dominant nuclides emitting $$gamma$$ ray or neutron, etc. in order to develop a Monte Carlo N-Particle Transport Code (MCNP) of the HALW tank. In addition, $$gamma$$ ray source spectra simulated by Particle and Heavy Ion Transport code System (PHITS) was developed by extracting peaks from the analysis data with germanium detector. These outputs are used for the fundamental data in the MCNP model which is then used to evaluate the type of detector, shielding design and measurement positions. In order to evaluate available radiations to measure outside the cell wall, continuous $$gamma$$ ray and neutron measurement were carried out and the results were compared to the simulation results. The measurement results showed that there are no FP peaks above 3 MeV. This paper presents an overview of the research plan, characteristics of HALW, development of source term for MCNP, simulation of radiation dose from the HALW tank and radiation measurement results at outside of cell wall.

Journal Articles

Improved holdup blender assay system (IBAS) slope validation measurements to improve nuclear material accountancy of high alpha holdup

LaFleur, A. M.*; Nakamura, Hironobu; Menlove, H. O.*; Mukai, Yasunobu; Swinhoe, M. T.*; Marlow, J. B.*; Kurita, Tsutomu

Proceedings of 37th ESARDA Annual Meeting (Internet), p.435 - 441, 2015/08

The IBAS (Improved Holdup Blender Assay System) system for safeguards and nuclear material accountancy (NMA) of holdup measurements is used at PCDF. The purpose of this detector is to measure the doubles rate from each glovebox in order to determine the mass of Pu holdup. In order to establish calibration curves for the IBAS detector and improve the holdup measurement methodology, JAEA conducted the IBAS calibration exercise with LANL support using MOX standards in 2010. In 2011, a cleanout exercise was performed and the results showed that the holdup removed from the glovebox had a significantly higher alpha term (alpha = 15.8 - 31.5) than the MOX standards (alpha = 0.67) used to establish the 2010 calibration curves. To further investigate these findings, JAEA conducted slope validation measurements in 2013 to confirm the validity of IBAS calibration slopes for the case of high alpha holdup. This paper describes the IBAS slope validation tests, analysis of the experimental results, and the evaluation of the need for a correction factor for the high alpha holdup. Quantifying the alpha term of the holdup in each glove box and understanding how this value changes over time is important to improving the overall NMA at PCDF. The results from this work will provide invaluable experimental data that directly supports safeguards and NMA measurements of plutonium holdup in gloveboxes.

Journal Articles

Design and implementation of $$^{10}$$B+$$^{3}$$He integrated continuous monitor (BHCM) to holdup monitoring in glove boxes

Mukai, Yasunobu; LaFleur, A. M.*; Nakamura, Hironobu; Menlove, H. O.*; Swinhoe, M. T.*; Marlow, J. B.*; Kurita, Tsutomu

Proceedings of INMM 55th Annual Meeting (Internet), 8 Pages, 2014/07

In order to improve the safeguards and nuclear material accountancy of holdup measurements and establish an alternative technology for $$^{3}$$He shortage, we have designed the $$^{10}$$B + $$^{3}$$He Integrated Continuous Monitor (BHCM) and implemented the measurements to continuously monitor the holup in gloveboxes at Plutonium Conversion Developoment Facility. In this paper, we present the outline of BHCM, the comparison between MCNP simulations and the measured results in preliminaly test and a demonstration of process monitoring ability during operation to see the relation between Totals trend and operational status by using $$^{10}$$B detection tubes.

Journal Articles

Proposal of direct alpha estimation technique by using ring ratio in the Continuous Neutron Monitor (CNM)

Mukai, Yasunobu; Nakamura, Hironobu; Fujisaku, Sakae; Kurita, Tsutomu; LaFleur, A. M.*; Menlove, H. O.*; Marlow, J. B.*

Kaku Busshitsu Kanri Gakkai (INMM) Nippon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2013/10

In case of the Pu mass determination in scattered powder in a GB using Continuous Neutron Monitor (CNM) with totals, self-multiplication of neutron (M) and $$alpha$$ value are properly required to be set. M can be easily estimated by a simulation code, but it is very difficult to estimate $$alpha$$ value by such a simulation because interactions between $$alpha$$ ray generated from Pu and impurities are not consistent. Therefore, we tried to examine an estimation technique of $$alpha$$ value by direct measurement. As a result, by measuring the samples taken from the scattered powder using a multiplicity counter with a dual ring structure of He-3 tubes, we could confirm a good correlation between ring ratio (inner / outer ring count rates) and the $$alpha$$ values. Thus, we can estimate $$alpha$$ value in the powder directly by the ring ratio measurement. By applying this technique to CNM and designing a new detector with a double layer structure of neutron detection tubes, we had a prospect that CNM would be able to measure the Pu mass continuously.

Journal Articles

Proposal of direct alpha estimation technique by using ring ratio in the continuous neutron monitor (CNM)

Nakamura, Hironobu; LaFleur, A. M.*; Mukai, Yasunobu; Hayashi, Hiroyuki*; Menlove, H. O.*; Marlow, J. B.*; Kurita, Tsutomu

Proceedings of INMM 54th Annual Meeting (CD-ROM), 8 Pages, 2013/07

To improve safeguards and material accountancy of holdup measurements, a continuous neutron monitor (CNM) that continuously monitors the singles rate from holdup in glove boxes was designed and implemented at PCDF. In totals neutron counting, it is impossible to get Pu mass directly from the singles count rate without predetermination of alpha value and multiplication(M). In case of holdup deposits, since M can be seen as 1, the determination of the alpha value by direct measurement of the holdup is very important. In this reserach, we have developed a new approach called Direct Alpha Estimation technique. To establish the relation, the ring ratio of the FCAS which has dual ring He-3 tubes was applied. By using different alpha of samples, relation between alpha and ring ratio was studied. As a result, a good correlation between them was obtained. Thus, since the ring ratio can estimate alpha value, we would propose that this technique with dual ringed CNM be extended to not only Pu mass determination, but also to monitor the impurity contents or Pu isotopic composition change in holdup.

Journal Articles

Design and implementation of a passive neutron counter to continously monitor holdup in glove boxes

LaFleur, A. M.*; Nakamura, Hironobu; Menlove, H.*; Marlow, J.*; Swinhoe, M. T.*; Mukai, Yasunobu; Kurita, Tsutomu

Proceedings of INMM 53rd Annual Meeting (CD-ROM), 8 Pages, 2012/07

To improve the safeguards and nuclear material accountancy of holdup measurements, a continuous neutron monitor (CNM) that continuously monitors the singles rate from holdup in gloveboxes was design and implemented at PCDF. The holdup currently in the gloveboxes at PCDF is from LWR recycle plutonium. In the near future, different Pu isotopic compositions from Fugen spent fuel will be transferred to PCDF. The different Pu isotopics of MOX-B fuel will result in much higher neutron emission rates compared to that from LWR spent fuel. Thus, the CNM is needed to establish baseline measurements of the existing holdup as a function of time prior to the introduction of the plutonium into the process equipment. It is considered that these baseline measurements can then be compared to post-process measurements to holdup after introduction of MOX-B fuel to determine the relative increase in holdup in the gloveboxes, and will help to avoid anticipated problems concerning safeguards or nuclear material accountancy.

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