[en] Full text of publication follows: The skyshine effect of neutrons and photons is an important issue for high-energy accelerators to estimate an environmental dose for the public living near facilities. The simple equations and parameters evaluated by several authors like G. Stapleton have been used in many paper and reports. In this study, equations and parameters were compared with each other to estimate the environmental effect of the PALXFEL operation. The skyshine effect of the 10 GeV electrons striking a thick Cu target was investigated. The PHITS and the FLUKA Monte Carlo codes were used to verify the accuracy of those equations and parameters. The practical geometry like a thick concrete tunnel and a ground condition was considered to evaluate properties of a neutron skyshine and an environmental dose. The ground-shine effect was found to be a little big at the real geometry estimation. This created a discrepancy between this Monte Carlo simulation and the simple equation in estimating an environmental dose. The new equation and parameters are evaluated by the Monte Carlo simulations that use the PHITS and the FLUKA. (authors)

[en] The neutron exposure accelerator system for biological effect experiments (NASBEE) has been developed to study biological effects of fast neutrons. NASBEE has been used to experimentally obtain several endpoints of the biological effects to fast neutrons. NASBEE neutron beams are characterised as energy spectrum, absorbed dose energy distribution and space distribution. The neutron energy spectrum extends to 9 MeV and a broad peak at 2.3 MeV. Neutron and photon absorbed doses occupy 82% and 18%, respectively, of the NASBEE neutron beam. We also developed narrowly-collimated neutron beams for irradiating fast neutrons to only lungs of mice. Absorbed dose distributions and beam profile of the collimated neutron beam were measured. For application of NASBEE, we innovated a real-time and non-destructive method of beam profile measurement on a target under large beam current irradiation. NASBEE has been widely used for not only biological study but also for physical and biological dosimetry. (authors)

[en] The Large Hadron Collider (LHC) at CERN started beam operations in 2008 and has clearly outperformed initial expectations. At the two biggest LHC experiments, ATLAS and CMS, the delivered integrated luminosity (which refers to the number of inelastic interactions during a certain time interval) for 2011 has been exceeded by a factor of almost 6 compared with its initial goal given at the beginning of 2010. LHCb and ALICE are operating already at their nominal luminosities and even above. Consequently, radiation levels in the LHC experiments are increasing. Further, the amount of radioactive material inside the experiments is becoming larger. Predictions of the expected residual dose rate during accesses are necessary in order to plan and co-ordinate work activities inside the experimental caverns. The Monte-Carlo particle transport code FLUKA was used to assess the expected prompt and residual dose rates at the LHC experiments. Further, the code was used to calculate the amount of material which would become radioactive and therefore requires special treatment and alertness when being handled, modified, stored or shipped. Estimates of radiation levels are presented and compared with the first measurements. An outlook of the expected radiation levels after several additional years of LHC operation is also given. (authors)

[en] Radionuclides, including ³H, ⁷Be, and ²²Na, are produced by high-energy nuclear reactions in the cooling water used to cool magnetic horns at the Japan Proton Accelerator Research Complex (J-PARC) Neutrino Experimental Facility. The origin of each nuclide is discussed by comparing the experimentally determined concentrations with results from PHITS calculations. The chemical behaviour of the radionuclides in water is dependent on the element being considered. Certain nuclides exhibit complex behaviour and become distributed inhomogeneously in the water-circulation system. In particular, ⁷Be nuclides, dominant gamma-ray emitters in the cooling-waters, exist in the water as both water-soluble ions and colloidal species. After passing through the de-ionizer, some amount of ⁷Be remains in the water, mainly as colloidal species. In addition, ⁷Be tends to adsorb on the metal piping and metallic components of the circulation system. The behaviour of ⁷Be contrasts with that of ³H (or T), which exists as tritiated water (HTO) and distributes homogeneously throughout the water cooling system. (authors)

[en] The shielding experiment was carried out using the Antiproton Production Target Station (Pbar) of Fermilab under the collaboration study of JASMIN: 'Japanese and American Study of Muon Interaction and Neutron detection'. In the experiment, the neutron flux distributions in the shielding assembly were obtained by means of multi-foil activation method. Neutron spectra in the energy range between 1 and 100 MeV were deduced from the experimental data using the fitting method, which was newly developed in this study. The experimental data were compared with the theoretical calculation of the particle transportation code: PHITS. The optimum value of neutron attenuation length λ was tentatively deduced by applying the experimental data to the Moyer's model. (authors)

[en] Geant4 is a tool-kit for the simulation of the passage of particles through matter. To demonstrate its capability in shielding applications, we have submitted Geant4 results to the SATIF 'Inter-comparison Problems of Neutron Attenuation' since 2006. Because Geant4 takes the tool-kit approach, the user is allowed flexibility in choosing not only geometry but also physics processes as implemented in a physics list. For the benefit of users, the 'Shielding' physics list, which we used in the comparison, is included in the release of Geant4. The latest Geant4 result obtained by using this physics list is measured against the experimental data of the BNL AGS benchmarks and presented in this paper. The agreement with data was found to be slightly worse than that for SATIF-10. After a detailed investigation, we found that the difference is mainly caused by the change of internal nucleon-nucleon cross-section in a cascade model. We confirmed that by switching back to the original cross-section, the agreement with data returns to the level of SATIF-10. Besides this physics list, the current Geant4 provides about 20 so-called reference physics lists and the results from these, together with brief explanations about the character of each list, are also presented. (authors)

[en] The design of LCLS-II X-ray Transport and Diagnostic (XTOD) system does not have the shielding wall separating electron dump line from Front End Enclosure (FEE), therefore any forward radiation may directly challenge the end wall. A series of radiation protection features are designed to protect users behind the end wall from the mixed radiation environment including FEL, spontaneous radiation, Bremsstrahlung and possible electron beam in accident. Detailed Monte Carlo studies are implemented for various beamline configurations, considering both normal operation and accidental electron beam loss, and the crucial requirement on the end wall is benchmarked by using both FLUKA and MARS. The leakage of Bremsstrahlung and spontaneous radiation along photon beam pipes into the experimental hall are also studied. It is found that a local safety collimator after the first mirror can help reduce the thickness and cost of the end wall, and a proper collimator system can sufficiently limit radiation leakage through photon beam pipes. (authors)

[en] We have developed a method to measure isotopic fragmentation reaction cross-sections as excitation functions in a single heavy ion irradiation experiment. The method consists of measurement of velocity, dE/dx and kinetic energy of projectile fragments originated in a thick target bombarded by mono-energetic heavy ions. Identifying isotopic identity by ΔE-E method and measuring kinetic energy by TOF method, isotopic fragmentation cross-sections are obtained as a function of energy. This method was tested against the simulation by FLUKA for a bombardment of 400 MeV/u ¹⁶O on a thick carbon target. The result shows cross-sections for production Li, Be, B, and C from ¹⁶O are successfully obtained above about 50 MeV/u as a function of energy. (authors)

[en] Full text of publication follows: The European Spallation Source (ESS) is a European common effort in designing and building a next generation large-scale user facility for studies of the structure and dynamics of materials. The ESS target, moderators and reflectors system through interactions with 5 MW proton beam (2.5 GeV, 20 Hz) will produce long pulse (2.8 ms width) neutrons in sub-thermal and thermal energy range. These neutrons are further transported to a variety of neutron scattering instruments. The aim of this work is to assess the strategy to be used for the safe handling and shipping of the ESS target and associated shaft. For safe maintenance, during operation as well as handling, transport and storage of the components of the ESS target station after their lifetime, detailed knowledge is required about the activation induced by the impinging protons and secondary radiation fields. The Monte Carlo transport code MCNPX2.6.0 was coupled with CINDER90 version 07.4 to calculate the residual nuclide production in the target wheel and associated shaft. Dose equivalent rates due to the residual radiation were further calculated with the MICROSHIELD and MCNPX codes using photon sources resulting from CINDER. Various decay times after ceasing operation of the target components were considered. The activation and decay heat density distributions of the target system together with the derived dose rates were analysed to assess the best strategy to be used for their safe removal and transport to a hot cell, eventual dismantling, storage on-site and shipping off-site as intermediate level waste packages. The derived photon sources were used afterwards to design the shielded exchange flasks that are needed to remove and transport the target after its lifespan to a hot cell. Design of a multipurpose cask able to accommodate the different highly activated components of the ESS target station and ship them to external conditioning facility is intended to be developed. For this purpose, the photon source term of target and shaft was derived taking into consideration previously estimated decay time on-site prior the cask loading. The main criterion used for optimisation of the thickness and material selection of the shielding of the flasks, in agreement with Swedish legislation and ADR provisions, is that the dose rate must not exceed 2 mSv h-1 on the outer surface and 0.1 mSv h-1 at a distance of 1 m. The calculated parameters for the shield of the target will be used for detailed design and manufacturing of the exchange flask. Obtained results for the off-site shipping cask are discussed in order to derive the requirements to be fulfilled for the type B(U) package design approval. (authors)

[en] Accelerator-driven systems require the use of high energy Mega-Watt proton beams, in combination with a nuclear reactor core operating in subcritical mode. Between the challenges in the design, key points are the radiation shielding and the minimisation of the induced activation. The present study has been done to optimise the design of the MYRRHA facility at SCK.CEN in Mol (Belgium), where a 600 MeV, 4 mA proton beam will be produced and transported through a linear accelerator up to a LBE spallation target, located inside the core of a LBE-cooled reactor, operating at 94 MW when coupled with the proton accelerator. To assess some aspects of the shielding of the proton beamline, as well as to fix the activation problems that heavily influence the design, extensive simulations have been performed with the FLUKA Monte Carlo code. In the first part of this work a systematic study has been finalised to estimate the neutron production and the radioactivity induced by the MYRRHA proton beam in typical materials used in the accelerator structures. The results of this study allow optimising the design of the elements devoted to the total or partial beam absorption (beam dump, collimators). It will be shown, in particular, how a suitable material configuration can improve the accessibility and the long-term treatment of the irradiated elements. (authors)