Measurement of (n,xnγ) Reactions of Interest for the New Nuclear Reactors

J. C. Thiry,C. Borcea,P. Dessagne,J. C. Drohe,E. Jericha,H. Karam,M. Kerveno,A. J. Koning,A. Negret,A. Pavlik,A. Plompen,C. Rouki,G. Rudolf,M. Stanoiu 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The design of Generation IV nuclear reactors and the research of new fuel cycles require knowledge of the cross sections of different nuclear reactions. Our research is focused on cross section measurements of (n,xnγ) reactions occurring in these new reactors. The aim is to measure unknown cross sections and to reduce the uncertainty on present data relative to reactions and isotopes present in transmutation or regeneration processes. The current work consists of studying ^(232)Th(n,n'γ) and ^(235)U(n,xnγ) reactions in the fast neutron energy domain (up to 20 MeV). The experiments are performed at the GEel LINear Accelerator (GELINA) which delivers a pulsed, white neutron beam at IRMM, Belgium. The time characteristics of the beam enable us to measure neutron energies with the time of flight (TOF) technique. The neutron induced reactions (in this case inelastic scattering and (n,2n) reactions) are identified by online prompt γ spectroscopy with an experimental setup including 4 HPGe detectors. A double layered fission chamber is used to monitor the incident neutron flux. The experimental setup and analysis methods will be presented and a comparison between the obtained cross sections and the TALYS predictions will be discussed. This work is a first step in the preparation of the measurement of ^(233)U(n,xnγ) reactions, which are completely unknown at this stage although of very high importance in the ^(232)Th regeneration process.

Status of the JEFF Nuclear Data Library

A. J. Koning,E. Bauge,C. J. Dean,E. Dupont,U. Fischer,R. A. Forrest,R. Jacqmin,H. Leeb,M. A. Kellett,R. W. Mills,C. Nordborg,M. Pescarini,Y. Rugama,P. Rullhusen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The status of the Joint Evaluated Fission and Fusion file (JEFF) is described. Recently, the JEFF-3.1.1 nuclear data library was released and shortly after adopted by the French nuclear power industry for inclusion in their production and analysis codes. Recent updates include actinide evaluations, materials evaluations that have emerged from various European nuclear data projects, the activation library, the decay data and fission yield sub-libraries, and fusion-related data files from the European F4E project. The revisions were motivated by the availability of new measurements, modelling capabilities and trends from integral experiments. Validations have been performed, mainly for criticality, reactivity temperature coefficients, fuel inventory, decay heat and shielding of thermal and fast systems. The next release of the library, JEFF-3.2, will be discussed. This will contain among others a significant increase of covariance data evaluations, modern evaluations for various structural materials, a larger emphasis on minor actinides and addition of high-quality gamma production data for many fission products.

Modern Nuclear Data Evaluation: Straight from Nuclear Physics to Applications

A. J. Koning,D. Rochman 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The nuclear data field comprises differential measurements, theory development, nuclear model codes, resonance analysis, evaluation, ENDF formatting, data processing and integral validation.A software system, built around the TALYS code, will be presented in which all of these essential nuclear data components are seamlessly integrated into one approach. This system brings back nuclear data evaluation to its essence: The starting information is no longer an ENDF-6 file, but a set of selected differential experiments, resonance parameters and a nuclear model input file.After this, computer power does the rest.The implications of this are unprecedented. A few are:\begin{itemize}\item Complete ENDF-6 nuclear data libraries, such as TENDL, including covariance matrices, for many isotopes, particles, energies, reaction channels and secondary quantities. All isotopic data files are mutually consistent and will soon rival those of the major world libraries.\item Exact uncertainty propagation from basic nuclear physics to applied (reactor) calculations based on a Monte Carlo approach (``Total'' Monte Carlo).\end{itemize}

Nuclear Data Uncertainty Propagation: Total Monte Carlo vs. Covariances

D. Rochman,A. J. Koning,S. C. van der Marck,A. Hogenbirk,D. van Veen 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Two distinct methods of propagation for basic nuclear data uncertainties to large scale systems will be presented and compared. The "Total Monte Carlo" method is using a statistical ensemble of nuclear data libraries randomly generated by means of a Monte Carlo approach with the TALYS system. These libraries are then directly used in a large number of reactor calculations (for instance with MCNP) after which the exact probability distribution for the reactor parameter is obtained. The second method makes use of available covariance files and can be done in a single reactor calculation (by using the perturbation method). In this exercise, both methods are using consistent sets of data files, which implies that covariance files used in the second method are directly obtained from the randomly generated nuclear data libraries from the first method. This is a unique and straightforward comparison allowing to directly apprehend advantages and drawbacks of each method. Comparisons for different reactions and criticality-safety benchmarks from ^(19)F to actinides will be presented. We can thus conclude whether current methods for using covariance data are good enough or not.

Measurements of Inelastic Neutron Scattering at 96 MeV from Carbon, Iron, Yttriumand Lead

A. Ohrn,C. Gustavsson,M. Blann,V. Blideanu,J. Blomgren,S. Chiba,H. Duarte,F. Haddad,C. Kalbach,J. Klug,A. Koning,C. Le brun,C. Lebrun,F. -R. Lecolley,X. Ledoux,N. Marie-noury,P. Mermod,L. Nilsson,M. O 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Inelastic neutron scattering for ^(12)C, ^(56)Fe, ^(89)Y and ^(208)Pb have been measured at 96 MeV at the The Svedberg Laboratory in Uppsala and double-differential cross sections are reported. Data cover an excitation energy range of 0-45 MeV and the angular intervals are 28 - 58˚ for ^(12)C, 26 - 65˚ for ^(56)Fe and 26 - 52˚ for ^(89)Y and ^(208)Pb. In this experiment, neutron detection is based on conversion to protons in an active scintillator converter. An analysis technique in which the neutron spectra have been obtained through a folding procedure using the response of the detector system has been used. The results are compared to and are in reasonable agreement with several model predictions and with inelastic neutron scattering data at 65 MeV from University of California, Davis, USA.

What Can We Expect from the Use of Nuclear Models Implemented inMCNPX at Projectile Energies below 150 MeV? Detailed Comparision with Experimental Data

A. Yu. Konobeyev,U. Fischer,A. J. Koning,H. Leeb,S. Leray,Y. Yariv 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Intranuclear cascade models implemented in MCNPX, Bertini, ISABEL, CEM, andINCL4 combined with pre- equilibrium models, and evaporation models Dresnerand ABLA are used for the simulation of particle interactions with matter incases where evaluated data are not available. Calculated cross-sections,however, are now available with the TENDL data, a complete collection ofnuclear data libraries in MCNPX format, for all materials, up to 200 MeV. Inthe present work cross-sections of proton induced reactions (p,x) calculatedusing the nuclear models, and TENDL, implemented in MCNPX are compared withexperimental data. Several thousands measured cross-sections for targetnuclei with the atomic number from 12 to 83 at incident proton energies from0 to 150 MeV are taken into account for the comparison. Various statisticalcriteria are applied for the quantification of the difference betweencalculated cross-sections and experimental data. The results obtainedindicate which MCNPX models are best to be used for applications below 150 MeV. Furthermore, they show what degree of accuracy one can expect from theuse of MCNPX models instead of evaluated data.

Implementation of the Geometry Dependent Hybrid Model in TALYS

A. Yu. Konobeyev,U. Fischer,P. E. Pereslavtsev,A. J. Koning,M. Blann 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The geometry dependent hybrid model (GDH) developed by M.Blann and suppliedby the models for the non-equilibrium cluster emission was implemented inthe TALYS code. A number of subroutines from the ALICE and ALICE/ASH codeswere introduced in TALYS after appropriate modifications. Commoncomputations as those relating to binding energies, the optical model andothers are performed by means of TALYS. The value of the TALYS inputvariable ``preeqmode'' equal to 5 is reserved for the use of the GDHapproach for the calculation of the pre-compound energy distributions ofnucleon and light clusters. A comparison with calculations using theoriginal ALICE and ALICE/ASH codes, on one hand, and experimental data, onthe other hand, is given. The advantages of the implementation of the GDHmodel in the TALYS code are discussed.

Towards Nuclear Data Evaluations Based on Many Body Theory

S. Hilaire,A. J. Koning,S. Goriely 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The increasing need for cross sections far from the valley of stability poses a challenge for nuclear reaction models. So far, predictions of cross sections have relied on more or less phenomenological approaches, depending on parameters adjusted to available experimental data or deduced from systematic relations. While such predictions are expected to be reliable for nuclei not too far from the experimentally known regions, it is clearly preferable to use more fundamental approaches, based on sound physical bases, when dealing with very exotic nuclei. Thanks to the high computer power available today, all the ingredients required to model a nuclear reaction can now be (and have been) microscopically (or semi-microscopically) determined starting from the information provided by a nucleon-nucleon effective interaction. This concerns the nuclear masses, the optical model potential, the total nuclear level densities, the photon strength functions, as well as the fission barriers. All these nuclear model ingredients, traditionnaly given by phenomenological expressions, now have a microscopic counterpart implemented in the TALYS nuclear reaction code. We are thus now able to perform fully microscopic cross section calculations. We will discuss both the quality of these ingredients and the impact of using them instead of the usually adopted phenomenological parameters.

International Cooperation in Nuclear Data Evaluation

M. Herman,J. Katakura,A. J. Koning,C. Nordborg 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The OECD Nuclear Energy Agency (NEA) is organising a co-operation between the major nuclear data evaluation projects in the world. The co-operation involves the ENDF, JEFF, and JENDL projects, and, owing to the collaboration with the International Atomic Energy Agency (IAEA), also the Russian BROND and the Chinese CENDL projects. The Working Party on international nuclear data Evaluation Cooperation (WPEC), comprised of about 20 core members, manages this co-operation and meets annually to discuss progress in each evaluation project and also related experimental activities. The WPEC assesses common needs for nuclear data improvements and these needs are then addressed by initiating joint evaluation efforts. The work is performed in specially established subgroups, consisting of experts from the participating evaluation projects. The outcome of these subgroups is published in reports, issued by the NEA. Current WPEC activities comprise for example a number of studies related tonuclear data uncertainties, including a review of methods for the combined use of integral experiments and covariance data, as well as evaluations of some of the major actinides, such as ^(235)U and ^(239)Pu. This paper gives an overview of current and planned activities within the WPEC.

Nuclear Data Uncertainty Propagation for a Sodium Fast Reactor

D. Rochman,A. J. Koning,D. F. Dacruz,S. C. van der Marck 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Nuclear data uncertainties are propagated from basic theory to a full core model of the Kalimer-600 Korean type Sodium Fast Reactor (SFR) using the TALYS nuclear code system, the "Total Monte Carlo" (TMC) approach and perturbation methods developed at NRG. Nuclear data uncertainties from sodium, iron, and some actinides will be presented together with their impact on parameters such as the sodium void coefficient and k_eff. One of the advantages of the TMC method is that it avoids approximations used in perturbation theories, by applying an exact uncertainty propagation approach. Additionally, full nuclear data uncertainties (cross sections, nu-bar as well as single and double differential data) can be considered.