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Mukai, Yasunobu; Nakamichi, Hideo; Kobayashi, Daisuke; Nishimura, Kazuaki; Fujisaku, Sakae; Tanaka, Hideki; Isomae, Hidemi; Nakamura, Hironobu; Kurita, Tsutomu; Iida, Masayoshi*; et al.
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 8 Pages, 2017/04
TRP has stored the plutonium in solution state for long-term since the last PCDF operation in 2007 was finished. After the great east Japan earthquake in 2011, JAEA had investigated the risk against potential hazard of these solutions which might lead to make hydrogen explosion and/or boiling of the solution accidents with the release of radioactive materials to the public when blackout. To reduce the risk for storing Pu solution (about 640 kg Pu), JAEA planned to perform the process operation for the solidification and stabilization of the solution by converted into MOX powder at PCDF in 2013. In order to perform PCDF operation without adaption of new safety regulation, JAEA conducted several safety measures such as emergency safety countermeasures, necessary security and safeguards (3S) measures with understanding of NRA. As a result, the PCDF operation had stared on 28th April, 2014, and successfully completed to convert MOX powder on 3rd August, 2016 for about 2 years as planned.
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.
He Alternative Neutron Detectors (ASAS), 1; Design and fabrication of ASAS detectorOzu, Akira; Tobita, Hiroshi; Kureta, Masatoshi; Tanigawa, Masafumi; Mukai, Yasunobu; Nakamichi, Hideo; Nakamura, Hironobu; Kurita, Tsutomu; Seya, Michio
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-36-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/12
Against the background of the serious shortage of He gas, the Japan Atomic Energy Agency (JAEA) has newly developed an alternative ZnS ceramic scintillation neutron detector for the safeguards, with the support of the government (MEXT). A demonstrator of plutonium inventory sample assay system (ASAS) has been also developed as an alternative HLNCC (High Level Neutron Coincidence Counter). The results from numerical simulations using Monte-Carlo code MCNPX showed that the fundamental performances of ASAS equipped with the 24 alternative neutron detectors, such as neutron detection efficiency and die-away time, equal to or higher than those of conventional HLNCC could be obtained. Here we present the inner mechanical structure of ASAS, together with the results of the simulating design.
Mukai, Yasunobu; Nakamura, Hironobu; Tanigawa, Masafumi; Nakamichi, Hideo; Umino, Yoshinori; Fujisaku, Sakae; Kimura, Takashi; Kurita, Tsutomu
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-36-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/12
When the unauthorized removal of nuclear materials (NM) from glovebox (GB) by an insider happens, it needs to be detected and reported immediately. In this time, for utilization of the security counterplan, the feasibility of a new detection concept for the unauthorized removal was investigated with implementation of several experiments considering actual GB operation. In general, the detection method using radiation monitor is thought of easily. However, it is very difficult to distinguish between authorized NM movement during operation and the unauthorized removal. To solve this subject, JAEA focused on negative pressure monitoring of GB, and investigated a new detection concept combining the neutron and negative pressure monitoring. As a result of the experiments in small-scale GB, it was revealed that this new concept had the capability to detect the unauthorized removal and to alarm to central alarm station rapidly, and had the possibility to enhance the effectiveness of the current physical protection measures.
Nakamura, Hironobu; Mukai, Yasunobu; Tobita, Hiroshi; Nakamichi, Hideo; Ozu, Akira; Kureta, Masatoshi; Kurita, Tsutomu; Seya, Michio
Proceedings of 37th ESARDA Annual Meeting (Internet), p.45 - 53, 2015/08
JAEA conducted an R&D project to develop a new type of neutron detector using ZnS/
B
O
ceramic scintillator (as an alternative neutron detector to He-3) with support of Japanese government. The design of the JAEAs alternative system (ASAS: Alternative Sample Assay System using ceramic scintillator tubes) refers basically to the INVS (INVentory Sample assay system) which is the passive type of neutron assay system equipped total 18 He-3 tubes and capable of measuring the small amount of Pu in the MOX powder or Pu nitrate solution in a vial for nuclear material accountancy and safeguards verification. In order to prove the alternative technology and the performance instead of He-3 detector, and to establish Pu measurement capability, JAEA developed and fabricated ASAS equipped 24 alternative ceramic scintillator tubes (which is equivalent to the same counting efficiency of INVS) and demonstrated. The demonstration activity implemented the confirmation of reproducibility about sample positioning, optimization of detector parameters, counting statistical uncertainty, stability check and figure of merit (FOM) using Cf check source and actual MOX powder in PCDF (Plutonium Conversion Development Facility). In addition, performance comparison between the current INVS and the ASAS was also implemented. In this paper, we present demonstration results with design information with Monte-Carlo simulation code (MCNP).
Nakamura, Hironobu; Tanigawa, Masafumi; Mukai, Yasunobu; Nakamichi, Hideo; Umino, Yoshinori; Fujisaku, Sakae; Kimura, Takashi; Kurita, Tsutomu
Proceedings of INMM 56th Annual Meeting (Internet), 8 Pages, 2015/07
In the MOX handling facilities, many types and amount of nuclear materials (NM) that are relatively easy to access are used in a GB. In order to prevent unauthorized removal of NM from the GB by an insider, based on the Japanese regulation which was referred from INFCIRC/225 Rev.5, the 2 person rule are being introduced at the area where NM handling GB are installed. As an example of usage of the security counterplan for the detection of unauthorized removal of NM, a new proposal of detection concept for the unauthorized removal by operators were investigated with implementation of several experiments considering actual GB operation. In general, it is considered that normal concept is to use radiation monitor (
or neutron) to detect the event by checking the variation of monitoring data. However, it is thought that distinguish between authorized NM movement during operation and the unauthorized removal (sample bag-out from GB) is very difficult. To solve this subject, JAEA studied and proposes a new concept about negative pressure monitoring in the GB in addition to the radiation monitoring. It is thought that the hybrid monitoring concept between pressure and radiation provides the detection alarm for it with central alarm station (CAS) accurately and rapidly with high integrity, and helps to complement current 2 person rule.
Mukai, Yasunobu; Nakamura, Hironobu; Nakamichi, Hideo; Kurita, Tsutomu; Noguchi, Yoshihiko*; Tamura, Takayuki*; Ikegame, Ko*; Shimizu, Junji*
Proceedings of INMM 56th Annual Meeting (Internet), 9 Pages, 2015/07
The PIMS used at Rokkasho Reprocessing Plant can quantify plutonium amount in each process vessel located inside glovebox by means of neutron measurement. Since the PIMS is not used for the neutron coincidence counting, it is very important to maintain that those constants meet the actual process condition. PIMS was calibrated in 2006, and then JNFL has been started to measure the Pu amount directly in each glovebox for the purpose of facility NMA. However, it was found that PIMS counting was unexpectedly and continuously increased during long time of inter-campaign. In order to find out the main cause, JAEA and JNFL jointly conducted several investigations. In the investigations, correctness of system parameters and relevant constants, behavior of the neutron generation when MOX powder is stored in actual glovebox for a long time (to see O/M and moisture change) and the behavior focused on the relation between MOX powder and light element using inside glovebox (fluorine is included in the PTFE which is used in many gloveboxes as packing of instruments) were experimentally confirmed using MOX powder in PCDF. As a result, since the same behavior happened in the actual PIMS was confirmed in the testing environment in which MOX powder coexists with fluorine, it is concluded that the main potential cause of PIMS is the increasing of the probability of (
, 
) reactions by a contact between PTFE and MOX powder.
Nakamichi, Hideo; Nakamura, Hironobu; Beddingfield, D.*; Mukai, Yasunobu; Kurita, Tsutomu
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-33-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2012/10
Plutonium holdup in gloveboxes (GBs) are measured by HBAS (passive neutron based NDA, Holdup Blender Assay System) for the material control and accountancy (MC&A) at Plutonium Conversion Development Facility (PCDF). In the case that the GBs are installed close to one another, the cross-talk which means neutron double counting among GBs should be corrected properly. Though we used to use predetermined constants as the cross-talk correction, a new correction methodology for neutron cross-talk among the GBs with inventory changes is required for the improvement of MC&A. In order to address the issue of variable cross-talk contributions to holdup assay values, we applied a dynamic cross-talk correction (DCTC) method, based on the distributed source-term analysis approach, to obtain the actual doubles derived from the cross-talk between multiple GBs. As a result of introduction of DCTC for HBAS measurement, we could reduce source biases from the assay result by estimating the reliable doubles-counting derived from the cross-talk. Therefore, we could improve HBAS measurement uncertainty to about 10% which is a half of conventional system. Since the DCTC methodology can be used to determine the cross-correlation among multiple inventories in small areas, it is expected that this methodology can be extended to the knowledge of safeguards by design.
Nakamura, Hironobu; Beddingfield, D.*; Montoya, J.*; Nakamichi, Hideo; Mukai, Yasunobu; Kurita, Tsutomu
Proceedings of INMM 53rd Annual Meeting (CD-ROM), 9 Pages, 2012/07
Plutonium holdup inventory in gloveboxes are measured by HBAS for the nuclear material accountancy (NMA) at PCDF. Because the gloveboxes are installed close to one another, we must make a correction for neutron cross-talk between the gloveboxes. In order to address the issue of variable cross-talk contributions to holdup assay values, we developed a dynamic cross-talk correction (DCTC) method to obtain the actual doubles signal cross-talk between multiple gloveboxes. With the HBAS improvement, the DCTC improves PCDF NMA by eliminating the double-counting of material that stems from cross-talk in the holdup assay data and eliminates this source of bias in the assay results. Since the DCTC methodology can be used to determine the cross-correlation among multiple inventories in small areas and substantially reduce cross-talk-induced biases in assay results, it is expected that DCTC technology can reflect as a safeguards-by-design.
Nakamichi, Hideo; Beddingfield, D. H.*; Nakamura, Hironobu; Mukai, Yasunobu; Kurita, Tsutomu
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-31-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2010/12
The Distributed Source-Term Analysis (DSTA) technique provides user with knowledge of the location of neutron-producing materials and the magnitude of activity in the large volume to be evaluated. We aimed that this technique can be used to identify the physical location and activity of holdup in the glove box. By using relationships between source and volume determined by MCNPX calculation, we developed a Glove Box Cleanout Assistance Tool (BCAT). The tool can be applied to the operator during cleanout to increase recovered material, to decrease unmeasured inventory, and to perform the cleanout effectively in order to reduce operator radiation-exposure. In order to demonstrate the BCAT performance, neutron measurements were performed around actual glovebox environment. As a result of the analysis, not only the more concrete holdup locations and the activities that we experimentally estimate the place to recover were determined, but also the new hidden holdup could be found out. This knowledge provides new effective cleanout methodology. Consequently, it is expected that the nuclear material accountancy for entire bulk-handling facility can be improved.
Nakamura, Hironobu; Beddingfield, D. H.*; Nakamichi, Hideo; Mukai, Yasunobu; Yoshimoto, Katsunobu
IAEA-CN-184/59 (Internet), 7 Pages, 2010/11
In order to reduce radioactivity of liquid waste generated at PCDF, a neutralization precipitation processes by sodium hydroxide precipitation is used. We call the precipitate after calcining as Sludge. The Pu amount in the sludge sample is normally determined by sampling and DA. The sludge contains many chemical components. For example, Pu, U, Am, SUS components, halogens, NaNO (main component), residual NaOH, and moisture. They are mixed together as an impure heterogeneous sludge sample. As a result, there is a large uncertainty in the sampling and DA that is currently used at PCDF. In order to improve the material accounting in PCDF, we performed a feasibility study using neutron multiplicity assay for impure sludge samples. We have measured selected sludge samples using a commercial multiplicity counter which is called FCAS (Fast Carton Assay System) which was designed by JAEA and Canberra. For unknown samples, using 14-hour measurements, we could obtain quite low statistical uncertainty on Doublesand Triples count rate although the alpha value is extremely high and FCAS efficiency is relatively low for typical multiplicity counters. Despite the detector efficiency challenges and the material challenges, we have been able to obtain assay results that greatly exceed the accountancy requirements for retained waste materials.
Nakamura, Hironobu; Beddingfield, D. H.*; Nakamichi, Hideo; Kurita, Tsutomu
Proceedings of INMM 51st Annual Meeting (CD-ROM), 9 Pages, 2010/07
The Distributed Source-Term Analysis (DSTA) technique has been used in a variety of safeguards applications to determine the location and quantity of material contained within large sample volumes. The DSTA method can provide the user with knowledge of the location of neutron-producing materials and the magnitude of the localized activity. A facility operator can use this information to identify the physical location of holdup during cleanout activities. In this paper, we present the concept of using the DSTA method as a 
(BCAT) that is used by operator during cleanout activities to increase recovered material and reduce facility MUF. In addition to the above effects, this BCAT concept provides that operator radiation-exposure and unmeasured inventory can be also reduced. We also present the actual powder recovering result performed in PCDF and comparison result between recovered material amount and calculated amount by BCAT.
Nakamura, Hironobu; Beddingfield, D. H.*; Nakamichi, Hideo; Kurita, Tsutomu
Proceedings of INMM 51st Annual Meeting (CD-ROM), 9 Pages, 2010/07
The Distributed Source-Term Analysis (DSTA) technique has been used in a variety of safeguards applications to determine location and quantity of material contained within large sample volumes. It can provide user with knowledge of the location of neutron-producing materials and magnitude of the localized activity. Operator can use this information to identify the physical location of holdup during cleanout operations. In this paper, we present the concept of using the DSTA method as a (BCAT) that is used by operator during cleanout to increase recovered material, to decrease unmeasured inventory, and to perform the cleanout activity effectively in order to reduce operator radiation-exposure. We confirmed good consistency between the difference of neutron activity before and after cleanout calculated by BCAT and neutron activity of actual recovered material.
Hayashi, Kimio; Nakagawa, Tetsuya; Onose, Shoji; Ishida, Takuya; Nakamichi, Masaru; Katsuyama, Kozo; Iwamatsu, Shigemi; Hasegawa, Teiji; Kodaka, Hideo; Takatsu, Hideyuki; et al.
JAEA-Technology 2009-007, 168 Pages, 2009/03
JAEA-Technology-2009-007.pdf:31.88MB
In-pile functional tests of breeding blankets have been planned by Japan Atomic Energy Agency (JAEA), using a test blanket module (TBM) which will be loaded in the International Thermonuclear Experimental Reactor (ITER). In preparation for the in-pile functional tests, JAEA has been being performed irradiation experiments of lithium titanate (LiTiO), which is the first candidate of solid breeder materials for the blanket of the demonstration reactor (DEMO) under designing in Japan. The present report describes (1) results of a detailed design and trial fabrication tests of a dismantling apparatus for irradiation capsules which were used in irradiation experiments by the Japan Materials Testing Reactor (JMTR) of JAEA, and (2) results of a preliminary investigation of a glove box facility for post-irradiation examinations (PIEs). In the detailed design of the dismantling apparatus, datailed specifications and the installation methods were examined, based on results of a conceptual design and basic design. In the trial fabrication, cutting tests were curried out by making a mockup of a cutting component. Furthermore, a preliminary investigation of a glove box facility was carried out in order to secure a facility for PIE work after the capsule dismantling, which revealed a technical feasibility.
Hayashi, Kimio; Nakagawa, Tetsuya; Onose, Shoji; Ishida, Takuya; Kodaka, Hideo; Katsuyama, Kozo; Kitajima, Toshio; Takahashi, Kozo; Tsuchiya, Kunihiko; Nakamichi, Masaru; et al.
JAEA-Technology 2008-010, 68 Pages, 2008/03
JAEA-Technology-2008-010.pdf:11.31MB
In-pile functional tests of breeding blankets for fusion reactors have been planned by Japan Atomic Energy Agency (JAEA), using a test blanket module (TBM) which will be loaded in ITER. The present report describes a conceptual investigation and a basic design of the dismantling process for irradiation capsules which were used in irradiation experiments by the Japan Materials Testing Reactor (JMTR) of JAEA. In the present design, the irradiation capsule is cut by a band saw; the released tritium is recovered safely by a purge-gas system, and is consolidated into a radioactive waste form. Furthermore, adoption of the inner-box enclosing the dismantling apparatus has brought a prospect to be able to utilize an existing hot cell (beta- cell) equipped with usual wall material permeable to tritium, without extensive refurbishing of the cell. Thus, the present study has indicated the feasibility of the present dismantling process for the irradiated JMTR capsules containing tritium.
Isomae, Hidemi; Nakamura, Hironobu; Matsumoto, Masaki; Kato, Yoshiyuki; Nakamichi, Hideo; Koiso, Katsuya*; Shoji, Kaoru*
no journal, ,
Ring monitor by glass dosimeter was designed and applied to the radiation management for glove box operation. The radiation management method and the irradiation test results are introduced in this report.
Nakamura, Hironobu; Nakamichi, Hideo; Takaya, Akikazu; Shoji, Kaoru*; Matsumoto, Masaki; Fujisaku, Sakae; Yoshimoto, Katsunobu
no journal, ,
For the MOX conversion test by using plutonium nitrate solution that is recycled by Fugen MOX spent fuel, JAEA had performed temperature evaluation for plutonium solution receiving tank (annular shape), and had established the guideline of thermal effect by comparing the measured temperature with designed temperature.
Fujisaku, Sakae; Nakamura, Hironobu; Takaya, Akikazu; Nakamichi, Hideo; Matsumoto, Masaki; Shoji, Kaoru*; Yoshimoto, Katsunobu
no journal, ,
For the MOX conversion test by using plutonium nitrate solution that is recovered by Fugen MOX spent fuel, JAEA had perform the temperature evaluation for MOX powder and had established the guideline for thermal effect by comparing measured temperature with designed temperature.
Nakamichi, Hideo; Hirono, Kenji*; Shoji, Kaoru*; Nakamura, Hironobu; Matsumoto, Masaki; Fujisaku, Sakae; Yoshimoto, Katsunobu
no journal, ,
In order to establish the conversion technology development test regarding MOX powder handling during transportation when high burn-up plutonium is used, temperature measurement on the canister in a transportation cask and powder property analysis were performed. As a result of the test, effective guideline of anticipated temperature on the canister could be obtained.
Tanigawa, Masafumi; Kato, Yoshiyuki; Kurita, Tsutomu; Kusano, keiichi*; Otaka, Akihiro*; Nakamichi, Hideo*
no journal, ,
no abstracts in English
