Although luminescence of water lower in energy than the Cerenkov-light threshold during proton and carbon-ion irradiation has been found, the phenomenon has not yet been implemented for Monte Carlo simulations. The results provided by the simulations lead to misunderstandings of the physical phenomenon in optical imaging of water during proton and carbon-ion irradiation. To solve the problems, as well as to clarify the light production of the luminescence of water, we modified a Monte Carlo simulation code to include the light production from the luminescence of water and compared them with the experimental results of luminescence imaging of water. We used GEANT4 for the simulation of emitted light from water during proton and carbon-ion irradiation. We used the light production from the luminescence of water using the scintillation process in GEANT4 while those of Cerenkov light from the secondary electrons and prompt gamma photons in water were also included in the simulation. The modified simulation results showed similar depth profiles to those of the measured data for both proton and carbon-ion. When the light production of 0.1 photons/MeV was used for the luminescence of water in the simulation, the simulated depth profiles showed the best match to those of the measured results for both the proton and carbon-ion compared with those used for smaller and larger numbers of photons/MeV. We could successively obtain the simulated depth profiles that were basically the same as the experimental data by using GEANT4 when we assumed the light production by the luminescence of water. Our results confirmed that the inclusion of the luminescence of water in Monte Carlo simulation is indispensable to calculate the precise light distribution in water during irradiation of proton and carbon-ion.

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Sweden and Finland are preparing for final deposition of spent nuclear power fuel. The adopted method is to encapsulate spent nuclear fuel in copper canisters filled with iron before deposition in a deep bedrock repository. The canisters will have a diameter of about one metre, which makes examination of the content in sealed canisters virtually impossible with any known technique today. Two methods for tomography of sealed canisters have been studied, high-energy neutron tomography and cosmic-ray muon tomography. Monte Carlo simulations using MCNPX have shown that it would indeed be possible to produce images of good resolution of thick massive objects, like these canisters, using high-energy neutrons. The cost for installing such a method would, however, be very high. GEANT simulations, supported by experimental tests, indicate that tomography using the natural flux of cosmic-ray muons results in images of lower quality, but to a much more modest cost, acceptable to the application. Figure 1: Canisters for spent BWR nuclear fuel. The canister consists of a cylindrical copper shell with a pressure-bearing insert of nodular iron. The outer diameter is 1.05 m and the length 4.83 m [1].

Abstract.Over the past years an experimental programme has been run at the neutron beam of The Svedberg Laboratory with the aim to study light-ion production induced by 96 and 175 MeV neutrons for a wide variety of targets. The measurements have been conducted using the Medley facility which allows measurement of p, d, t, He-3 and alpha production at fixed angles (from 20 to 160 degrees in steps of 20 degrees) over a wide dynamic range. An overview of the results obtained at the now finished campaign at 96 MeV will be given. Since 2007 we have been running at 175 MeV with C, O, Si, Fe, Bi and U as target material. Preliminary results from these measurements will be shown and compared to model calculations with Talys-1.2. We also summarize the Medley measurements of elastic np and nd scattering and of angular distributions of fission fragments.

We have developed a remote scintillation detector using a CCD spectrometer and a red-emitting scintillator coupled with a 20 m optical fiber for ultra-high-dose conditions. Gamma rays were detected with a conventional deep-red-emitting ruby scintillator and Cs2HfI6, which is a novel material with 700 nm red emission and a high light output. The scintillators were irradiated with gamma rays from a 60Co source under an effective dose rate from ∼0.002 to ∼1 kSv h−1. The integrated area of the Cs2HfI6 emission spectra was larger than that of the ruby, and good linearity of the Cs2HfI6 signal as a function of dose rate was confirmed.