The total cross section of the nuclear reaction 8 Y(p,7) Zr has been measured over the proton energy range EP=1.6-2.4 MeV. The results are compared with the predictions of statistical model calculations. 1 I n t r o d u c t i o n A very important point in nuclear astrophysics models is the reproduction of the abundances of the so called p-nuclei, a class of nuclei heavier than iron, lying on the proton rich side of the chart of nuclides between , Se and Hg. The p-process is a nucleosynthetic mechanism through which p-nuclei are produced. It therefore includes reactions such as (7,n). (7,p), (7,ö) and their inverse as well. The predictions of the p-process models do not reproduce satisfactory the abundances in the A=90 mass region. This problem could be attributed either to the lack of experimental data or to the uncertainty in the theoretical estimates of the statistical models [1-3]. It is obvious that there is a need for precise measurements of (p,7) cross sections and furthermore for tests of the validity of the Hauser-Feshbach model predictions in the A=90 mass region. These facts have motivated the present work which is concentrated in measuring the cross section of the nuclear reaction 8 Y(p.7) Zr over the proton energy range Ep=1.6 -2.4 MeV. 154 2 Experimental details The measurements have been carried out at the 4 MV single-ended Dynamitron accelerator of the University of Stuttgart, as well as at the 5.5 MV Van De Graaf Tandem accelerator of the Institute of Nuclear Physics of NCSR "Demokritos", Athens. Both machines have been calibrated during the experiments by means of the 992 keV resonance of the reaction 2 7 AI(p,7) 2 8 Si. The experimental setup shown in Fig. 1 of the former measurements consisted of 4 HPGe detectors (three of them with 100% relative efficiency and one with 80%), all shielded with BGO detectors for Compton suppression, which were placed on a turnable table. Hence, the 7-angular distributions of all the 7-transitions of interest have been measured at each beam energy. In order to check properly the level Experimental setups

The total cross section of the nuclear reaction 89Y(p,7)90Zr has been measured over the proton energy range EP=1.6-2.4 MeV. The results are compared with the predictions of statistical model calculations

The space and time configurations of the dissociation of He-8 into He-6+n+n, on C and Pb targets, have been explored simultaneously for the first time. The final-state interactions in the n-n and He-6-n channels are successfully described within a model that considers independent emission of neutrons from a Gaussian volume with a given lifetime. The dissociation on C target exhibits a dominant sequential decay through the ground state of He-7, consistent with neutrons being emitted from a Gaussian volume of r(nn)(rms) = 7.3 +/- 0.6 fm with a n-n delay in the sequential channel of 1400 +/- 400 fm/c, in agreement with the lifetime of He-7. The lower-statistics data on Pb target correspond mainly to direct breakup, and are well described using the n-n volume measured, without any n-n delay. The validity of the phenomenological model used is discussed.

The unbound nucleus He-7 has been investigated via the reaction of a 16.8 MeV He-6 radioactive ion beam on a Be-9 target. The measurement of the outgoing 8Be through its well characterized two-alpha decay permitted the energy of the He-6 +n system to be reconstructed. Through comparison with a complete Monte Carlo simulation incorporating R-matrix lineshapes, the He-7 ground state was determined to lie 0.380(28) MeV above the neutron decay with a width of Gamma = 0.179(21) MeV. A neutron spectroscopic factor SF = 0.608(18) was extracted in agreement with the most recent calculations. Significant evidence was found for a broad resonance lying at 2.6(2) MeV above threshold with a Gamma(FWHM) = 2.3(3) MeV. These parameters are fully consistent with the properties of 1/2(-) state reported by Wuosmaa et al. [Phys. Rev. C 72, 061301(R) (2005)]. Limits were also put on the presence of narrow resonances seen in earlier experiments.

The unbound nucleus $^{7}\\mathrm{He}$ has been investigated via the reaction of a 16.8 MeV $^{6}\\mathrm{He}$ radioactive ion beam on a $^{9}\\mathrm{Be}$ target. The measurement of the outgoing $^{8}\\mathrm{Be}$ through its well characterized two-$\\ensuremath{\\alpha}$ decay permitted the energy of the $^{6}\\mathrm{He}+n$ system to be reconstructed. Through comparison with a complete Monte Carlo simulation incorporating $R$-matrix lineshapes, the $^{7}\\mathrm{He}$ ground state was determined to lie 0.380(28) MeV above the neutron decay with a width of $\\mathrm{\\ensuremath{\\Gamma}}=0.179(21)$ MeV. A neutron spectroscopic factor $\\text{SF}=0.608(18)$ was extracted in agreement with the most recent calculations. Significant evidence was found for a broad resonance lying at 2.6(2) MeV above threshold with a ${\\mathrm{\\ensuremath{\\Gamma}}}_{\\text{FWHM}}=2.3(3)$ MeV. These parameters are fully consistent with the properties of $1/{2}^{\\ensuremath{-}}$ state reported by Wuosmaa et al. [Phys. Rev. C 72, 061301(R) (2005)]. Limits were also put on the presence of narrow resonances seen in earlier experiments.

Active cooling systems are vulnerable to component failures or loss of electrical power. Consequently, to increase the reliability of the system as a whole, adequate redundancy for these components as well as electrical back-up power sources must be provided. The Fukushima Daiichi accident however demonstrates that, despite redundancy and alternative power sources, an extended loss of cooling can occur. The present paper presents a conceptual design of a passive cooling system with a power removal capacity from 1 kW up to 1 MW. This system, constituted by different fluid loops, can provide adequate confinement in cases it is necessary. The proposed design is modeled with the FlowMaster simulation tool providing both steady state and dynamic responses. The results show the relationship between the system constraints (heat load and temperature difference between hot and cold source) and the design parameters of the system. A valuable application of passive systems is spent fuel storage cooling where adequate heat removal must be provided to the fuel elements at all time and confinement is of outmost importance. The proposed approach is applied to the design of the hot cell cooling in which the spent fuel elements of the future MYRRHA facility are handled.

While siphon breakers are well known and widely used, the relationship between the undershooting height (defined as the height difference between the siphon breaking device and the final water volume level) and the system design is poorly understood. The system code RELAP5 simulation tool has been tested to assess its ability to correctly predict the undershooting height. The results show the deficiency of such 1D code to correctly predict the stratification in the system piping leading to siphon breaking. This deficiency leads the code to over predict the undershooting height for large siphon breaking diameter. A typical application of siphon breaker device is nuclear spent fuel pools. Several piping systems are connected to these pools to ensure cooling, cleaning or level control while the stored fuel elements must be protected against fast loss of coolant accident. The present study extends the simulations performed with RELAP5 to a wide range of designs. It presents a method to conservatively assess the ability of the siphon breaking devices to prevent fuel uncovery in nuclear spent fuel pools. Additionally, the siphon breaking phenomenon has been studied with two-phase gas/liquid flow 2D Computational Fluid Dynamics (CFD) simulations in ANSYS CFX. Experimental results are compared with simulation results from both 1D system code and CFD. They are discussed to draw conclusions on the driving parameters and on the limits of available computational tools.

The elastic scattering and inclusive alpha-particle yield for the He-6 + Pb-206 system at an incident energy of 18 MeV, just below the nominal Coulomb barrier, have been measured. The alpha-particle yield at forward angles is also reported. The data are analyzed by means of continuum-discretized coupled-channels, distorted wave Born approximation, and coupled reaction channels calculations. Couplings to the one-neutron- and two-neutron-transfer reactions are found to be able to account for most of the absorption in the entrance channel.

Developers of High Temperature Reactors (HTR) worldwide acknowledge that the main asset for market breakthrough is its unique ability to address growing needs for industrial cogeneration of heat and power (CHP) owing to its high operating temperature and flexibility, adapted power level, modularity and robust safety features. A strong alliance between nuclear and process heat user industries is a necessity for developing such a nuclear system for the conventional process heat market, just as the electro-nuclear development required a close partnership with utilities. Initiating such an alliance is one of the objectives of the EUROPAIRS project (www.europairs.eu) presently on-going in the frame of the Euratom 7th Framework Programme (FP7). Although small and of short duration (21 months), EUROPAIRS is of strategic importance: it generates the boundary conditions for rapid demonstration of collocating HTR with industrial processes as proposed by the European High Temperature Reactor Technology Network (HTR-TN). This paper presents the main goals, the organization and the working approach of EUROPAIRS. It also presents the status of the viability assessment studies for coupling HTR with industrial end-user systems as one of the main pillars of the project. The main goal of the viability assessment is to identify developments required to remove the last technological and licensing barriers for a viable coupling scheme. The study is expected to result in guidelines for directing the choice of an industrial scale prototype.

In order to reduce the volume and the radiotoxicity of the nuclear waste coming from the operation of existing pressurized water reactors, accelerator-driven systems (ADSs) have been envisioned. The Lead-Cooled (Pb) European Facility for Industrial-Scale Transmutation (EFIT) (Pb-EFIT) plant is the first ADS design that has been going into a rather detailed engineering level. It is a lead-cooled, 385-MW(thermal) ADS prototype for minor actinide (MA) transmutation designed to achieve an optimal MA destruction rate of [approximately]42 kg/TW·h(thermal). The spallation target unit is located in the center of the diagrid where 800-MeV protons from the accelerator impinge on a free surface of lead exposed to vacuum. The core inlet temperature was set at 400°C to assure a sufficiently large safety margin to lead freezing, and the core outlet temperature was limited to 480°C to allow acceptable corrosion. The ferritic-martensitic 9% Cr steel T91 protected against corrosion with alumina FeCrAlY [GESA (Gepulste Elektronen Strahl Anlage) treatment]. The primary circuit is designed for effective natural circulation, i.e., relatively low pressure losses, and the design offers good protection for a heat removal system in case of a blackout accident. The EFIT plant is designed to have a low likelihood and a low degree of core damage, to eliminate the need for off-site emergency responses in case of a severe accident, to use an extensively reliable passive safety system to fulfill the safety functions, and to eliminate the need of alternating-current safety-grade power (no safety-grade diesel generator). Three systems contribute to the decay heat removal (DHR) function of Pb-EFIT: the steam generators, the direct reactor cooling system, and the isolation condenser system. The EFIT plant exhibits four primary pumps; eight steam generator units, each rated at 52 MW, provide heat removal under normal operation. On the secondary side, the water steam ensures a thermal efficiency of [approximately]40% with the superheated vapor secondary circuit, taking into account the electricity required by pumps (from both the primary circuit and the secondary circuits) but without deducing the power required for the accelerator. An estimate of the Pb-EFIT plant cost has been performed based mainly on experience and engineering judgment. A best estimate (base cost and contingency) of about €1890 million, with an overall uncertainty of 22%, has been found.

The most intense gamma-ray line observable from novae is likely to be from positron annihilation associated with the decay of 18F. The uncertainty in the destruction rate of this nucleus through the 18F(p,{\alpha})15O reaction presents a limit to interpretation of any future observed gamma-ray flux. Direct measurements of the cross section of both this reaction and the 18F(p,p)18F reaction have been performed between center of mass energies of 0.5 and 1.9 MeV. Simultaneous fits to both data sets with the R-Matrix formalism reveal several resonances, with the inferred parameters of populated states in 19Ne in general agreement with previous measurements. Of particular interest, extra strength has been observed above ECM \sim1.3 MeV in the 18F(p,p)18F reaction and between 1.3-1.7 MeV in the 18F(p,{\alpha})15O reaction. This is well described by a broad 1/2+ state, consistent with both a recent theoretical prediction and an inelastic scattering measurement. The astrophysical implications of a broad sub-threshold partner to this state are discussed.

Measurements of the He-4(Be-7, alpha)Be-7 and He-4(Be-7, p)B-10 reactions were performed using Be-7 beam energies of 7.1 and 23 MeV and a helium-4 target, employing the thick target technique. Resonances were observed between E-x(C-11) = 8.6 to 13.8 MeV. An R-matrix analysis was performed to characterize the spins and partial widths. This analysis showed that the observed sequence of states was consistent with that found for Li-7 + alpha resonant scattering populating resonances in B-11. A comparison of the proposed partial widths for decay with the Wigner limit indicates that several of the states are associated with cluster-like structures.

During the past ten years the present collaboration has carried out several experiments related with the study of radioactive nuclei. One of the topics in which we have centered our research, is the scattering of halo nuclei at energies around the Coulomb barrier. As part of this study, we present in this work a review of the results obtained from the scattering of He-6, Be-11 and Li-11. The presence of a "halo" in these exotic nuclei is found to have a striking effect on the dynamics of these reactions, making their study an interesting experimental problem and a challenge for existing reaction theories.

Experimental results of the elastic scattering of He-6 on Pb-208 at E-LAB = 22 MeV, measured at the CRC facility (Louvain-la-Neuve, Belgium), are presented, including results on the He-4 production channel. These data were taken with full angular coverage and high angular resolution. Both experimental cross sections are compared with continuum discretized coupled channels and distorted-wave Born approximation calculations, where direct breakup and transfer to the continuum processes are considered. The elastic data confirm the absence of the Coulomb rainbow, while the distribution of alpha particles indicates that such production is mostly generated by transfer to the continuum.

This work has been supported by the Spanish MICINN under projects FPA2005-04460, FPA200502379, FPA2006-13807-c02-01, FPA2007-63074, FPA2009-07653, FPA2009-07387 and FPA2010 22131-C02-01, by the Junta de Andalucia project FQM-4964, by the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042) and Programme Multi-Dark (CSD2009-00064), by the European Community-Access to Research Infrastructure action of the Improving Human Potential Program Contract, No. HPRI-CT-1999-00110, and by the Belgian Program P5/07 on interuniversity attraction poles of the Belgian-state Federal Services for Scientific, Technical and Cultural Affairs. L. Acosta acknowledges financial support by the Universidad de Huelva.

In this work we present new data for the sub-barrier fusion of the system He-6+Pb-206 obtained in the Centre de Recherches du Cyclotron (UCL), in Louvain-la-Neuve, Belgium. The preliminary results suggest the absence of fusion enhancement at sub-barrier energies.

Cross-sections for the production of 210Po nuclei in 6He + 206Pb collisions over the incident energy range 14-18MeV were measured by means of the activation technique and a radiochemical analysis. The elastic scattering at 18.0MeV was also measured providing a precise value for the 210Po production cross-section at this energy. The results are at variance with the earlier experimental data and rather in accord with the predictions of a density-dependent barrier penetration model for the fusion process. A proper treatment of beam energy distribution for the evaluation of the activation data is discussed.