Experimental analysis of neutron and background -ray energy spectra of 80-400 MeV Li(p,n) reactions under the quasi-monoenergetic neutron field at RCNP, Osaka University

Iwamoto, Yosuke; Sato, Tatsuhiko; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; Masuda, Akihiko*; Matsumoto, Tetsuro*; Iwase, Hiroshi*; Shima, Tatsushi*; Nakamura, Takashi*

EPJ Web of Conferences, 153, p.08019_1 - 08019_3, 2017/09

https://doi.org/10.1051/epjconf/201715308019

To develop 100-400 MeV quasi-monoenergetic neutron field, we measured neutron and unexpected -ray energy spectra of the Li(p,n) reaction with 80-389 MeV protons in the 100-m time-of-flight (TOF) tunnel at the Research Center for Nuclear Physics (RCNP). Neutron energy spectra with energies above 3 MeV were measured by the TOF method and energy spectra with energies above 0.1 MeV were measured by the automatic unfolding function of the radiation dose monitor DARWIN. For neutron spectra, the contribution of peak intensity to the total intensity integrated with energies above 3 MeV varied between 0.38 and 0.48. For -ray spectra, high-energetic -rays at around 70 MeV originated from the decay of were observed over 200 MeV. For the 246-MeV proton incident reaction, the contribution of -ray dose to neutron dose is negligible because the ratio of -ray to neutron is 0.014.

Shielding experiments of concrete and iron for the 244 MeV and 387 MeV quasi-mono energetic neutrons using a Bonner sphere spectrometer (at RCNP, Osaka Univ.)

Matsumoto, Tetsuro*; Masuda, Akihiko*; Nishiyama, Jun*; Iwase, Hiroshi*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; Yashima, Hiroshi*; Shima, Tatsushi*; et al.

EPJ Web of Conferences, 153, p.08016_1 - 08016_3, 2017/09

https://doi.org/10.1051/epjconf/201715308016

Neutron energy spectra behind concrete and iron shields were measured for quasi-monoenergetic neutrons above 200 MeV using a Bonner sphere spectrometer (BSS). Quasi-monoenergetic neutrons were produced by the Li(p,xn) reaction with 246-MeV and 389-MeV protons. The response function of BSS was also measured at neutron energies from 100 MeV to 387 MeV. In data analysis, the measured response function was used and the multiple neutron scattering effect between the BSS and the shielding material was considered. The neutron energy spectra behind the concrete and iron shields were obtained by the unfolding method using the MAXED code. Ambient dose equivalents were obtained as a function of a shield thickness successfully. For the case of the 244 MeV neutron incidence, the multiple neutron scattering effect on the effective dose is large under 50 cm thickness of the concrete shield.

Applicability of the two-angle differential method to response measurement of neutron-sensitive devices at the RCNP high-energy neutron facility

Masuda, Akihiko*; Matsumoto, Tetsuro*; Iwamoto, Yosuke; Hagiwara, Masayuki*; Satoh, Daiki; Sato, Tatsuhiko; Iwase, Hiroshi*; Yashima, Hiroshi*; Nakane, Yoshihiro; Nishiyama, Jun*; et al.

Nuclear Instruments and Methods in Physics Research A, 849, p.94 - 101, 2017/03

https://doi.org/10.1016/j.nima.2016.12.031

Quasi-monoenergetic high-energy neutron fields induced by Li(p,n) reactions are used for the response evaluation of neutron-sensitive devices. The quasi-monoenergetic high-energy field consists of high-energy monoenergetic peak neutrons and unwanted continuum neutrons down to the low-energy region. A two-angle differential method has been developed to compensate for the effect of the continuum neutrons in the response measurements. In this study, the two-angle differential method was demonstrated for Bonner sphere detectors, which are typical examples of moderator-based neutron-sensitive detectors, to investigate the method's applicability and its dependence on detector characteristics. Through this study, the adequacy of the two-angle differential method was experimentally verified, and practical suggestions were made pertaining to this method.

Hydrochemical disturbances measured in groundwater during the construction and operation of a large-scale underground facility in deep crystalline rock in Japan

Iwatsuki, Teruki; Hagiwara, Hiroki; Omori, Kazuaki; Munemoto, Takashi; Onoe, Hironori

Environmental Earth Sciences, 74(4), p.3041 - 3057, 2015/08

https://doi.org/10.1007/s12665-015-4337-3

Changes of hydrochemical condition resulting from large-scale underground facility construction to 500 m depth in sedimentary and granitic rock were evaluated at the Mizunami Underground Research Laboratory (MIU), Japan. The investigation of hydrochemical impact around the facility suggests that an understanding of hydrogeological structures, including hydrogeological compartments prior to facility construction and the locating of shafts/galleries in low permeability rock area is essential to minimize hydrochemical disturbances.

Methodology development for colloid investigation in groundwater

Omori, Kazuaki; Munemoto, Takashi; Hasegawa, Takashi; Shingu, Shinya*; Hagiwara, Hiroki; Iwatsuki, Teruki

JAEA-Research 2014-013, 29 Pages, 2014/08

JAEA-Research-2014-013.pdf:48.04MB

We summarized investigation method of colloid in groundwater. We examined the ultrafiltration of groundwater by using in-situ water monitoring system and batch type airtight container. Additionally, we examined the cross flow filtration method replaced by ultrafiltration. The knowledge of investigating methods is obtained.

Characterization of quasi-monoenergetic neutron source using 137, 200, 246 and 389 MeV Li(p,n) reactions

Iwamoto, Yosuke; Hagiwara, Masayuki*; Iwase, Hiroshi*; Yashima, Hiroshi*; Satoh, Daiki; Matsumoto, Tetsuro*; Masuda, Akihiko*; Pioch, C.*; Mares, V.*; Shima, Tatsushi*; et al.

Progress in Nuclear Science and Technology (Internet), 4, p.657 - 660, 2014/04

https://doi.org/10.15669/pnst.4.657

The authors measured the neutron energy spectra of the proton incident reaction on the lithium target with 137, 200, 246 and 389 MeV protons at several angles (0, 2.5, 5, 10, 15, 20, 25 and 30), using a time-of-flight (TOF) method employing organic scintillators NE213 at the Research Center for Nuclear Physics (RCNP) of Osaka University. For the neutron energy spectrum at 0, the ratio of the peak neutron intensity to the total one varied between 0.4 and 0.5 depending on the incident energy. In order to consider the correction required to derive the response in the peak region from the measured total response for high-energy neutron detectors, the authors showed the subtractions of H*(10) obtained at larger angles from the 0 data in the continuum part. It was found that subtracting the dose equivalent at about 22 from the 0 data reduces the continuum component most efficiency.

Shielding benchmark experiment using hundreds of MeV quasi-monoenergetic neutron source by a large organic scintillator

Hagiwara, Masayuki*; Iwase, Hiroshi*; Iwamoto, Yosuke; Satoh, Daiki; Matsumoto, Tetsuro*; Masuda, Akihiko*; Yashima, Hiroshi*; Nakane, Yoshihiro; Nakashima, Hiroshi; Sakamoto, Yukio; et al.

Progress in Nuclear Science and Technology (Internet), 4, p.327 - 331, 2014/04

https://doi.org/10.15669/pnst.4.327

We have developed several hundreds of MeV p-Li quasi-monoenergetic neutron fields in the Research Center for Nuclear Physics (RCNP), Osaka University, Japan. In this study, we extended the measurements to higher energy with a p-Li quasi-monoenergetic neutron source, which was produced from a 1.0-cm-thick lithium target bombarded with 246 and 389 MeV protons, using a larger NE213 scintillator of 25.4-cm in diameter and 25.4-cm in thickness. The large NE213 have good energy resolution for high energy neutrons, because it can stop recoil protons up to 180 MeV. The measured data are compared with the Monte-Carlo codes (PHITS with JENDL-HE data library) in the energy spectra, time spectra and the attenuation length of the peak neutrons. This comparison shows good agreement between experiments and calculations. The attenuation length estimated from the well-fitted curves with single exponential form will be useful for the practical shielding design of high energy accelerator facilities.

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2011

Kunimaru, Takanori; Mikake, Shinichiro; Nishio, Kazuhisa; Tsuruta, Tadahiko; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Sasao, Eiji; Hikima, Ryoichi; Tanno, Takeo; Sanada, Hiroyuki; et al.

JAEA-Review 2013-018, 169 Pages, 2013/09

JAEA-Review-2013-018.pdf:15.71MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II and the Phase III in 2011 fiscal year. This report shows the results of the investigation, construction and collaboration studies in fiscal year 2011, as a part of the Phase II and Phase III based on the MIU Master Plan updated in 2010.

Measurements and Monte Carlo calculations of forward-angle secondary-neutron-production cross-sections for 137 and 200 MeV proton-induced reactions in carbon

Iwamoto, Yosuke; Hagiwara, Masayuki*; Matsumoto, Tetsuro*; Masuda, Akihiko*; Iwase, Hiroshi*; Yashima, Hiroshi*; Shima, Tatsushi*; Tamii, Atsushi*; Nakamura, Takashi*

Nuclear Instruments and Methods in Physics Research A, 690, p.10 - 16, 2012/10

https://doi.org/10.1016/j.nima.2012.06.038

Secondary neutron-production double-differential cross sections (DDXs) have been measured from interactions of 137 MeV and 200 MeV protons in a natural carbon target. The data were measured between 0 and 25 in the laboratory. Benchmark calculations were carried out with the PHITS code using the evaluated nuclear data files of JENDL/HE-2007 and ENDF/B-VII, and the theoretical models of Bertini-GEM and ISOBAR-GEM. For the 137 MeV proton incidence, calculations using JENDL/HE-2007 generally reproduced the shape and the amount of experimental spectra well including the ground state of the N state produced by the C(p,n)N reaction. ISOBAR predicts the nucleon emission to the forward angles qualitatively better than the Bertini model and JENDL/HE-2007. These experimental data will be useful to evaluate the carbon data and as benchmark data for investigating the validity of the Monte Carlo simulation for the shielding design of accelerator facilities.

Monitoring of pore water pressure and groundwater chemistry at MSB-2 and MSB-4 boreholes in the MIU construction site; April, 2010 - March, 2011

Hagiwara, Hiroki; Shingu, Shinya; Kurita, Kazuaki*; Eguchi, Keita*; Horita, Masakuni*; Mizuno, Takashi

JAEA-Data/Code 2012-005, 67 Pages, 2012/06

JAEA-Data-Code-2012-005.pdf:3.42MB
JAEA-Data-Code-2012-005-appendix(CD-ROM).zip:0.74MB

Japan Atomic Energy Agency has been carried out investigations to understand the fluctuation of groundwater chemistry related to the shafts excavation at the Mizunami Underground Research Laboratory in Mizunami City, Gifu prefecture, Japan. The data for pore water pressure, water temperature and groundwater chemistry have been provided from two surface-based boreholes, MSB-2 and MSB-4 boreholes, installed a modular multilevel groundwater monitoring system (MP system). The monitoring has been conducted once in a month since April 2003. According to the results, the shaft excavation has caused drawdown of the hydraulic head and change in the groundwater chemistry in the MIU construction site. In this report, the data of monitoring at the MSB-2 and the MSB-4 boreholes from April 2010 to March 2011 were compiled. In addition, the monitoring results at the DH-2 borehole as part of Regional Hydrogeological Study project, are summarized as an appendix.