Uncertainty reduction of sodium void reactivity using data from a sodium shielding experiment

Maruyama, Shuhei; Endo, Tomohiro*; Yamamoto, Akio*

Journal of Nuclear Science and Technology, 61(1), p.31 - 43, 2024/01

https://doi.org/10.1080/00223131.2023.2244512

This study investigated the feasibility of reducing the uncertainty associated with fast-reactor-core design by sharing an experimental database between different fields (e.g., reactor physics and radiation shielding) using data assimilation techniques. As the first step in this study, we focused on the ORNL sodium shielding experiment and investigated the possibility of using the experimental data to reduce the uncertainty in sodium void reactivity (SVR), which is the most important safety parameter for sodium-cooled fast reactors. A sensitivity analysis based on the Generalized Perturbation Theory was performed for the sodium shielding experiment. Using the sensitivity coefficients evaluated here and those of the sodium void reactivity previously evaluated by the JAEA, we showed that sodium shielding experimental data can contribute to the uncertainty reduction of SVR by adopting the cross-section adjustment method. Based on this study, the uncertainty reduction effect is expected to be significant, especially for SVR dominated by neutron-leakage phenomena. Although new reactor physics experimental data on SVR may be difficult to obtain, the results of this study suggest that data from sodium shielding experiments can partially substitute for this role. This study demonstrated the value of the mutual use of integral experimental data in fast reactor designs.

Proposal on how to proceed with Verification and Validation of radiation shielding analyses

Okumura, Keisuke; Sakamoto, Yukio*; Tsukiyama, Toshihisa*

Shahei Kaiseki No V&V Gaidorain Sakutei Ni Mukete, p.4 - 8, 2023/03

https://www.aesj.net/uploads/com_vvshieldingcalc20230428_sup.pdf

no abstracts in English

Radiation shielding analysis of the upper structure of an accelerator-driven system

Iwamoto, Hiroki; Meigo, Shinichiro; Nakano, Keita; Yee-Rendon, B.; Katano, Ryota; Sugawara, Takanori; Nishihara, Kenji; Sasa, Toshinobu; Maekawa, Fujio

JAEA-Research 2021-012, 58 Pages, 2022/01

JAEA-Research-2021-012.pdf:7.23MB

A radiation shielding analysis was performed for the structure located above the spallation target of an accelerator-driven system (ADS), assuming one cycle of an 800 MW thermal and 30 MW beam power operation. In this analysis, the Monte Carlo particle transport code PHITS and the activation analysis code DCHAIN-PHITS were used. The structures to be analyzed are a beam duct above the target, a beam transport room located above the ADS reactor vessel, beam transport equipment, and the room ceiling. For each structure, the radiation doses and radioactivities during and after the operation were estimated. Furthermore, the shielding structure of the ceiling was determined. As a result, it was found that the radiation dose at the site boundary would be sufficiently lower than the legal limit by applying the determined shielding structure. Moreover, under the condition of this study, it was shown that the effective dose rate around the beam transport equipment positioned above the target after the operation exceeded 10 mSv/h, and that the maintenance and replacement of the equipment in the room would require remote handling.

Radiological estimation and validation for the Accelerator-Based Boron Neutron Capture Therapy Facility at the Ibaraki Neutron Medical Research Center

Nakashima, Hiroshi; Nakamura, Takemi; Kobayashi, Hitoshi*; Tanaka, Susumu*; Kumada, Hiroaki*

NEA/NSC/R(2021)2 (Internet), p.142 - 151, 2021/12

Aiming of development of facilities for boron neutron capture therapy (BNCT) that can be installed in hospitals, an accelerator-based BNCT facility is being developed at the Ibaraki Neutron Medical Research Center under a collaboration among the Japan Atomic Energy Agency, the High Energy Accelerator Research Organization, the University of Tsukuba, and other institutions. It consists of a proton accelerator, having a maximum beam power of 80 kW, and a target, moderator, collimator and shield (TMCS) system. For the design concept, to satisfy the BNCT beam conditions and achieve a low activation, the radiation behavior in the TMCS system was simulated by the Monte Carlo method and this system configuration was optimized accordingly. In addition, the radiation estimation of the TMCS system was verified via several experiments and its applicability for BNCT was proved. This report reviews the estimation and validation studies for the development of the accelerator-based BNCT facility.

Activation in injection area of J-PARC 3-GeV rapid cycling synchrotron and its countermeasures

Yamamoto, Kazami; Yamakawa, Emi*; Takayanagi, Tomohiro; Miki, Nobuharu*; Kamiya, Junichiro; Saha, P. K.; Yoshimoto, Masahiro; Yanagibashi, Toru*; Horino, Koki*; Nakanoya, Takamitsu; et al.

ANS RPSD 2018; 20th Topical Meeting of the Radiation Protection and Shielding Division of ANS (CD-ROM), 9 Pages, 2018/08

The existing beam power of the J-PARC Rapid Cycling Synchrotron is up to 500 kW, and higher radiation doses are concentrated in the injection area. These activations are caused by the interaction between the foil and the beam. To reduce dose exposure to workers near the injection point, we study a new design of the injection scheme. Experience has shown that eddy currents are generated in the metal flange near the magnet owing to the pulsed magnetic field, and the temperature exceeds 100 degrees C. The shield installed in the new injection system needs to have a layer structure, in which an insulator is inserted between iron shields to reduce the eddy current. From the results of the shielding calculation, even if 1 mm of polyethylene was inserted between two 9-mm-thick SUS 316 plates, which serve as shielding material, the shielding performance was reduced only about 5%, and we confirmed that it would function well.

Shielding effect on secondary cosmic-ray neutron- and muon-induced soft errors

Abe, Shinichiro; Sato, Tatsuhiko

Proceedings of Radiation Effects on Components and Systems Conference 2016 (RADECS 2016) (Internet), 5 Pages, 2016/00

https://doi.org/10.1109/RADECS.2016.8093141

Secondary cosmic-ray neutron have been recognized as a major cause of soft error for microelectronics on ground. Recently, the effect of secondary cosmic-ray muon on soft error is concerned as semiconductor devices become sensitive to radiation. In this study, we investigate the shielding effect on secondary cosmic-ray neutron- and muon-induced SER. Transports of secondary cosmic-ray neutrons and muons in a building are simulated by PHITS with considering distributions of energy and zenith-angle of secondary cosmic-rays by PARMA 4.0 which is the analytical model for estimating cosmic-ray fluxes nearly anytime and anywhere in the world. The calculated neutron fluxes are in surprisingly good agreement with measured data. The soft errors in 25-nm bulk-design NMOSFET caused by neutrons and muons in the open air and on the first floor of the building are analyzed based on the MSV model using PHITS. It is found that the shielding effect of the building only contributes to decrease neutron-induced SER. As a result, muon-induced SER is about 20% of that caused by neutron on the first floor. Therefore it is necessary to consider the secondary cosmic-ray muon-induced SER when reliability of devices used in the building is evaluated.

Homogeneity tests on neutron shield concrete

Okuno, Koichi*; Iikura, Hiroshi

Nuclear Science and Techniques, 25(S1), p.S010604_1 - S010604_5, 2014/12

http://www.j.sinap.ac.cn/nst/EN/10.13538/j.1001-8042/nst.25.S010604

no abstracts in English

Experiment and analyses for 14 MeV neutron streaming through a dogleg duct

Yamauchi, Michinori*; Ochiai, Kentaro; Morimoto, Yuichi*; Wada, Masayuki*; Sato, Satoshi; Nishitani, Takeo

Radiation Protection Dosimetry, 116(1-4), p.542 - 546, 2005/12

https://doi.org/10.1093/rpd/nci236

no abstracts in English

Nuclear "pasta" structures and the charge screening effect

Maruyama, Toshiki; Tatsumi, Toshitaka*; Voskresensky, D. N.*; Tanigawa, Tomonori; Chiba, Satoshi

Physical Review C, 72(1), p.015802_1 - 015802_11, 2005/07

https://doi.org/10.1103/PhysRevC.72.015802

no abstracts in English

Structured mixed phase at charged kaon condensation

Maruyama, Toshiki; Tatsumi, Toshitaka*; Voskresensky, D. N.*; Tanigawa, Tomonori; Chiba, Satoshi

Nuclear Physics A, 749, p.186c - 189c, 2005/03

no abstracts in English