Impact of PHITS spallation models on the neutronics design of an accelerator-driven system

Iwamoto, Hiroki; Nishihara, Kenji; Iwamoto, Yosuke; Hashimoto, Shintaro; Matsuda, Norihiro; Sato, Tatsuhiko; Harada, Masahide; Maekawa, Fujio

doi:10.1080/00223131.2016.1140598

Cited by 19 publications

(5 citation statements)

References 27 publications

(30 reference statements)

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“…Using the neutron capture cross sections deduced above, we estimated the time variation of the 205 Pb amount produced in a typical subcritical reactor in the ADS [7,67]. We assumed neutron beam fluxes of 5×10 14 , 5 × 10 15 , and 5 × 10 16 n/cm 2 /s at a neutron energy of 100 keV around the Pb-Bi target position [67]. Figure 11 shows calculated fractions (in units of weight percent; wt%) of 205 Pb relative to initial amount of Pb materials as a function of the irradiation period.…”

Section: B Evaluation Of the Neutron Capture Cross Section Of 205 Pbmentioning

confidence: 99%

Dipole strength distribution in Pb206 for the evaluation of the neutron capture cross section of Pb205

Shizuma¹,

Iwamoto²,

Makinaga³

et al. 2018

Phys. Rev. C

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The dipole strength distribution of 206 Pb was investigated via a nuclear resonance fluorescence experiment using bremsstrahlung produced with an electron beam at a kinetic energy of 10.5 MeV at the linear accelerator ELBE. We identified 88 states resonantly excited at energies from 3.7 to 8.2 MeV. The analysis of the measured γ-ray spectra includes the quasicontinuum of levels at high energy. Monte Carlo simulation of γ-ray cascades were performed to obtain the intensities of inelastic transitions and branching ratios of the ground state transitions. The extracted photo-absorption cross section show enhanced dipole strength at the excitation energies around 5.5 and 7 MeV, which may related to a pygmy dipole resonance. The present (γ, γ′) data combined with (γ, n) data from the literature were used for confining input parameters of the statistical calculation code CCONE to derive the neutron capture cross section of the unstable 205 Pb nucleus.

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Section: B Evaluation Of the Neutron Capture Cross Section Of 205 Pbmentioning

confidence: 99%

Dipole strength distribution in Pb206 for the evaluation of the neutron capture cross section of Pb205

Shizuma¹,

Iwamoto²,

Makinaga³

et al. 2018

Phys. Rev. C

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“…The helium and hydrogen implantation rates in this experiment were about 15 and 150 appm/dpa at 1.2 m in depth, respectively. These values were estimated by using PHITS code [14] assuming with the irradiation conditions from the LBE target in 1 st ADS, ex. 1 GeV proton energy, 20 mA/cm 2 flux and the 2 mm thickness beam window made of T91 [2].…”

Section: Simultaneous Ion Irradiation Experiments Have Been Conductedmentioning

confidence: 99%

Irradiation Influence on Swelling and Corrosion Behavior of ADS Beam Window Materials, T91 Steels, in Lead Bismuth

Okubo

Fujimura

2020

Proceedings of the 14th International Workshop on Spallation Materials Technology

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In an accelerator driven system (ADS), the beam window material of spallation neutron target will be heavily irradiated under severe conditions, where the displacement damage and high concentrations of helium and hydrogen atom accumulation in the material will occur simultaneously due to high energy spallation neutron and/or proton irradiations in the lead bismuth flow. A main materials issue dedicated to the ADS is the compatibility with the liquid metal of lead bismuth eutectic (LBE), such as liquid metal embrittlement (LME) and liquid metal corrosion (LMC). In this study, we address firstly the swelling behavior of the beam window materials, which is also important for the fuel claddings and connected indirectly with the oxidation reaction induced during irradiation or/and by the irradiation damage. Secondly, the LMC after ion irradiation of ferritic/martensitic steels, T91, are also addressed in the cases of self-ion irradiation and simultaneous irradiation with He and H atoms. The irradiations were performed at temperatures from 350 to 550°C up to 10-40 dpa. In the case of single ion irradiation (only displacement damage), no cavities were observed, but in the cases of dual and triple ion irradiations, many cavities were formed and caused swelling. It was concluded that helium and/or hydrogen enhanced the swelling induced by the simultaneous irradiation case and the peak swelling behavior appeared at an irradiation temperature around 450°C. It was found that, under simultaneous triple ion beams (Fe+He+H), H atoms affected significantly on the swelling development process. Comparing with the dual beams (Fe+He), the enhancement of cavity growth in the deeper region and the suppression of the growth in the medium depth region with changing the number density distributions of cavities might be caused by a fast diffusion of hydrogen atoms. From this result it can be concluded that the swelling of T91 steel depends on the implantation rates of He/dpa and H/dpa. The initial study was originally performed on LMC of T91 steels using the specimen irradiated at 450°C. After the corrosion test at 450°C in the LBE with low oxygen concentration, the surface of the triply irradiated area was covered by the oxide layer even though the non-irradiated area didn't show the enough oxide formation. Therefore, it is concluded that the irradiation can enhance the oxide layer formation supposed due to the two reasons of (1) enhancement of Fe diffusion caused by reducing activation energy of Fe atoms due to helium-vacancy complexes and vacancy clusters after the ion irradiation and (2) enhancement of O interstitial diffusion by radiation defects.

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“…Experimental validation of these modelling details is limited due to the challenges in performing accurate measurements of the secondary radiation field, with measurement precisions in the literature ranging from 20%-50% for secondary neutrons (Schneider and Hälg 2015). Although benchmarking for the different INC models has been performed for proton interactions with large atomic mass (typically Fe or Pb), the comparisons of the double-differential output have regularly ignored the lower particle energies and tissue targets seen in proton therapy (Boudard et al 2002, David et al 2011, Iwamoto et al 2016, Arce et al 2021. It should thus be acknowledged that MC users must accept some currently unknown uncertainty when using low energy INC modelling.…”

Section: Introductionmentioning

confidence: 99%

Comparison of out-of-field normal tissue dose estimates for pencil beam scanning proton therapy: MCNP6, PHITS, and TOPAS

Griffin

Yeom

Mille

et al. 2022

Biomed. Phys. Eng. Express

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Monte Carlo (MC) methods are considered the gold-standard approach to dose estimation for normal tissues outside the treatment field (out-of-field) in proton therapy. However, the physics of secondary particle production from high-energy protons are uncertain, particularly for secondary neutrons, due to challenges in performing accurate measurements. Instead, various physics models have been developed over the years to reenact these high-energy interactions based on theory. It should thus be acknowledged that MC users must currently accept some unknown uncertainties in out-of-field dose estimates. In the present study, we compared three MC codes (MCNP6, PHITS, and TOPAS) and their available physics models to investigate the variation in out-of-field normal tissue dosimetry for pencil beam scanning proton therapy patients. Total yield and double-differential (energy and angle) production of two major secondary particles, neutrons and gammas, were determined through irradiation of a water phantom at six proton energies (80, 90, 100, 110, 150, and 200 MeV). Out-of-field normal tissue doses were estimated for intracranial irradiations of 1-, 5-, and 15-year-old patients using whole-body computational phantoms. Notably, the total dose estimates for each out-of-field organ varied by approximately 25% across the three codes, independent of its distance from the treatment volume. Dose discrepancies amongst the codes were linked to the utilized physics model, which impacts the characteristics of the secondary radiation field. Using developer-recommended physics, TOPAS produced both the highest neutron and gamma doses to all out-of-field organs from all examined conditions; this was linked to its highest yields of secondary particles and second hardest energy spectra. Subsequent results when using other physics models found reduced yields and energies, resulting in lower dose estimates. Neutron dose estimates were the most impacted by physics model choice, and thus the variation in out-of-field dose estimates may be even larger than 25% when considering biological effectiveness.

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Impact of PHITS spallation models on the neutronics design of an accelerator-driven system

Cited by 19 publications

References 27 publications

Dipole strength distribution in Pb206 for the evaluation of the neutron capture cross section of Pb205

Dipole strength distribution in Pb206 for the evaluation of the neutron capture cross section of Pb205

Irradiation Influence on Swelling and Corrosion Behavior of ADS Beam Window Materials, T91 Steels, in Lead Bismuth

Comparison of out-of-field normal tissue dose estimates for pencil beam scanning proton therapy: MCNP6, PHITS, and TOPAS

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