Gas production in the MEGAPIE spallation target

AIP Conference Proceedings, 2005

Production rates of volatile elements following spallation reaction of 1.4 GeV protons on a liquid Pb/Bi target have been measured. The experiment was performed at the ISOLDE facility at CERN. These data are of interest for the developments of targets for accelerator driven systems such as MEGAPIE. Additional data have been taken on a liquid Pb target. Calculations were performed using the FLUKA and MCNPX Monte Carlo codes coupled with the evolution codes ORIHET3 and FISPACT using different options for the intra-nuclear cascades and evaporation models. Preliminary results from the data analysis show good comparison with calculations for Hg and for noble gases. For other elements such as I it is apparent that only a fraction of the produced isotopes is released. The agreement with the experimental data varies depending on the model combination used. The best results are obtained using MCNPX with the INCL4/ABLA models and with FLUKA. Discrepancies are found for some isotopes produced by fission using the MCNPX with the Bertini intranuclear cascade model coupled with the Dresner evaporation model.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2004

Spallation-neutron yields for protons at E p ¼ 420 and 590 MeV incident on thick Pb/Bi targets have been measured via activation analysis of Au and Mn foils at the PSI proton irradiation facility. The data were obtained with the waterbath method, in a novel variant that incorporates a detailed MCNPX simulation in the analysis procedure. They include slow-neutron fluence distributions at E p ¼ 300, 420 and 590 MeV, Cd-ratio distributions at E p ¼ 300 MeV and total n=p values of 6.0 ± 0.3 and 9.6 ± 0.4 at 420 and 590 MeV, respectively. The latter are in line with neutron-yield systematics for protons on thick Pb-targets, which are found to vary with remarkable regularity over a broad range of incident energies. The results of the present work, along with those obtained recently by various groups on thin and thick-target neutron spectra, neutron-multiplicities and the radio-nuclide inventory produced, constitute a database pertinent to the design and optimization of new, high-intensity spallation-neutron sources at these proton energies.

MEGAPIE, the first liquid metal target irradiated by a proton beam at the MW power level, was successfully operated in 2006. A continuous beam of 575 MeV protons with a current up to 1.35 mA irradiated the liquid lead-bismuth target placed in the SINQ target location at PSI (Switzerland) for a period of four months. The neutronic performance of the target was studied with the goals of validating the Monte Carlo codes used in the design of the target; additionally, the performance was compared with the solid Pb targets used before and after the MEGAPIE experiment. Absolute thermal and epithermal neutron fluxes were measured at various beam lines at the end of the SINQ target block (about 6-7 m from the centre of the target) and at a measuring station close to the center of the target. The results show a clear increase of the neutron flux delivered to the users with respect to the solid target irradiated before MEGAPIE, between a factor 1.6 and 1.8, depending on the beam lines. The ag...

Journal of Physics: Conference Series, 2006

Relativistic protons with energies 0.7-1.5 GeV interacting with a thick, cylindrical, lead target, surrounded by a uranium blanket and a polyethylene moderator, produced spallation neutrons. The spatial and energetic distributions of the produced neutron field were measured by the Activation Analysis Method using Al, Au, Bi, and Co radio-chemical sensors. The experimental yields of isotopes induced in the sensors were compared with Monte-Carlo calculations performed with the MCNPX 2.4.0 code.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2003

Nuclear Engineering and Design, 2008

The megawatt pilot experiment (MEGAPIE) has been launched by six European institutions (PSI, FZK, CEA, SCK-CEN, ENEA and CNRS), JAEA (Japan), DOE (US) and KAERI (Korea) with the aim to carry out an experiment, in the SINQ target location at PSI (Switzerland), to demonstrate the safe operation of a liquid metal (lead-bismuth eutectic, LBE) spallation target hit by a ∼1 MW proton beam. The European Commission has joined the MEGAPIE project through the 5-year (2001)(2002)(2003)(2004)(2005)(2006) project named MEGAPIE-TEST. This project has been formally concluded with an International Workshop, where the results and the lessons learned during the project have been summarised. This work presents a review of the outcome of that Workshop. (C. Fazio). the 5th Framework Programme. The Project has been formally concluded with an International Workshop where the most relevant results gained during the project have been discussed. The summary of these results is reported in this work.

Nuclear power production can benefit from the develop-ment of more comprehensive alternatives for dealing with long-term radioactive waste. One such alternative is an accelerator-driven subcritical reactor (ADSR) which has been proposed for both energy production and for burn-ing radioactive waste. Here we investigate the effects of the size of the ADSR spallation target on the total neutron yield integrated over the neutron energy and emission an-gle. The contribution to the total neutron yield from the (n, xn) neutron interactions is evaluated at proton beam ener-gies between 0.4 and 2 GeV. Calculations have been carried out with the GEANT4 simulation code using the Liege intranuclear cascade model and the results are compared to the the LAHET/MCNP code package predictions.

Proceedings of the 14th International Workshop on Spallation Materials Technology, 2020

The eleventh target (Target-11) of the Swiss spallation neutron source (SINQ) was in operation in 2015 and 2016. It was shut-down due to an incident in June 2016, during which the pressure drop in the cooling water loop increased significantly, and meanwhile, the activity of the cooling water also increased tremendously. The evidence indicated a serious failure of the target. As this is the first severe failure since SINQ was in operation in 1997, some post-irradiation examinations (PIE) were performed to analyze the failure mechanisms.

ND2007, 2007

The IS419 experiment at the ISOLDE facility at CERN dedicated to the measurement of production and release rates of volatile elements from an irradiated Pb/Bi target by a proton beam of 1/1.4 GeV has been completed. The release of He, Ne, Ar, Br, Kr, Cd, I, Xe, Hg, Po and At isotopes was investigated at different target temperatures, ranging from 250 • C to 600 • C. Three experimental methods were used for the mass-separated, ionized beams: i) implantation of short-and medium-lived isotopes in a tape and on-line detection with a HPGe γ detector; ii) implantation of longer-lived isotopes in Al foils and off-line detection with a HPGe detector; iii) a Faraday Cup used mainly for stable nuclides. The results were compared with predictions from the FLUKA and MCNPX codes using different options for the intra-nuclear cascades and evaporation/fission models. Results show good agreement with calculations for Hg and for noble gases. For other elements such as iodine it is apparent that only a fraction of the produced isotopes is released. The results from FLUKA and MCNPX with the INCL4/ABLA models are in general more satisfactory than those obtained using MCNPX with the standard Bertini/Dresner model combination. Interestingly also significant yields of 204−210 At isotopes were observed. At isotopes are produced either by (p, π − xn) charge exchange reactions on 209 Bi or by secondary reactions involving 3 He and 4 He. Despite the non-release of polonium from Pb/Bi targets at typical operation temperatures, a smaller amount of highly radiotoxic Po isotopes can actually be liberated indirectly as decay daughters of the released astatine.

Annals of Nuclear …, 2009

The MEGAPIE project aimed to design, build and operate a liquid metal spallation neutron target of about 1 MW beam power in the SINQ facility at the Paul Scherrer Institut (Villigen, Switzerland). This project is an important step in the roadmap towards the demonstration ...