[en] With charged-particle spectroscopy implemented on OMEGA, we have been able to routinely measure the particle spectra (both nuclear lines and continua) from a variety of capsule implosions. Important parameters such as fusion yields, fuel and shell areal densities, and ion temperatures can be readily deduced. We will report on details of this work with emphasis on the implosion physics

[en] This report describes the status of the development of fusion power alternatives and it's effect on climatic change issues

[en] The IAEA Co-ordinated Research Programme (CRP) on the Compilation and Evaluation of Fission Yield Nuclear Data has been established with the goal to improve the evaluation process, include the energy dependence of yields and full covariance information in the data base. The evaluation of experimental fission yield information is supplemented by semi-empirical model calculations. Measured fission yields are still insufficient to provide users with reliable data for the requested yield sets. Therefore, CRP participants elaborated and issued requests for further measurements: General requests, primarily for systematic studies, to help improving model parameters and evaluating the energy dependence of yields; tables of specific deficient yield data, where no or only one measurement exists, or where data are discrepant. (author)

[en] The ANSI/ANS 8.3 standard allows a maximum yield not to exceed 2 x 10 fissions to calculate requiring the alarm system to be effective. It is common practice to use this allowance or to develop some other yield based on past criticality accident history or excursion experiments. The literature on the subject of yields discusses maximum yields larger and somewhat smaller than the ANS 8.3 permissive value. The ability to model criticality excursions and vary the various parameters to determine a credible maximum yield for operational specific cases has been available for some time but is not in common use by criticality safety specialists. The topic of yields for various solution, metal, oxide powders, etc. in various geometry's and containers has been published by laboratory specialists or university staff and students for many decades but have not been available to practitioners. The need for best-estimate calculations of fission yields with a well-validated criticality excursion code has long been recognized. But no coordinated effort has been made so far to develop a generalized and well-validated excursion code for different types of systems. In this paper, the current practices to estimate fission yields are summarized along with its shortcomings for the 12-Rad zone (at SRS) and Criticality Alarm System (CAS) calculations. Finally the need for a user-friendly excursion code is reemphasized

[en] In burn-up calculations, accuracy of isotopic generation prediction strongly depends on the nuclear data, such as neutron cross sections, fission yields and decay constants. In this study, we perform burn-up calculations using JENDL-4.0, ENDF/B-VII.1 and JEFF-3.1.1, and compare the calculation results with PIE (Post Irradiation Examination) data. We also perform burn-up sensitivity analysis based on the generalized perturbation theory to clarify the cause of difference on isotopic generation between the libraries. As a result, there are large discrepancies between JEFF-3.1.1 and the others generally. Furthermore, we clarify their causes for each nuclide and energy group. For neutron cross sections, some nuclides have large discrepancies between JEFF-3.1.1 and the others, and they give large impacts on specific isotopic generation predictions. On fission yields, ones from Pu-239 and Pu-241 have large discrepancies between JEFF-3.1.1 and the others, and they give large impacts on specific isotopic generation predictions, especially Gd-160. Decay constant discrepancies do not give any large impacts on isotopic generation predictions. (author)

[en] This paper describes a functional slide rule that provides a readily usable in-hand method for estimating nuclear criticality accident information from sliding graphs, thereby permitting (1) the rapid estimation of pertinent criticality accident information without laborious or sophisticated calculations in a nuclear criticality emergency situation, (2) the appraisal of potential fission yields and external personnel radiation exposures for facility safety analyses, and (3) a technical basis for emergency preparedness and training programs at nonreactor nuclear facilities. The slide rule permits the estimation of neutron and gamma dose rates and integrated doses based upon estimated fission yields, distance from the fission source, and time-after criticality accidents for five different critical systems. Another sliding graph permits the estimation of critical solution fission yields based upon fissile material concentration, critical vessel geometry, and solution addition rate. Another graph provides neutron and gamma dose-reduction factors for water, steel, and concrete shields

[en] Dynamics of the compression of a magnetized plasma target by a heavy liner made of partially ionized high high-Z material is discussed. A 'soft-landing' (shockless) mode of the liner deceleration is analyzed. Conclusion is drawn that such mode is possible for the liners whose thickness at the time of the first contact with the target is smaller than, roughly, 10% of the initial (un-compressed) target radius. A combination of the plasma liner with one or two glide cones allows for a direct access to the area near the center of the reactor chamber. One can then generate plasma target inside the plasma liner at the optimum time. The other advantage of the glide cones is that they can be used to deliver additional fuel to the center of the target near the point of a maximum compression and thereby increase the fusion yield

[en] In our work we defined a scheme to update fission yields and their covariance matrices. We implemented a Generalised Linear Least Square (GLLS) updating procedure to produce inter-isotope fission yield correlations. At each update, a constraining equation was selected and the related set of observables calculated using the prior knowledge of the fission yield data and uncertainties. Then, available extra information on each observable was introduced into the system - e.g. a data set of direct measurements or uncertainties. Our GLLS-based updating tool calculates best-estimate posterior fission yields and covariance matrices which merge both the extra and prior data. The major result of the update is the generation of fission yield correlations. We created complete updated covariance matrices for 6 nuclides (Th²³², U²³³, U²³⁵, U²³⁸, Pu²³⁹ and Pu²⁴¹) and a total of 14 fissioning systems using the JEFF-3.1.1 files. The fission yield covariance matrices were tested against the criticality and nuclide inventory calculations of the REBUS single pin benchmark after one irradiation cycle. It appears that fission yield correlations reduce the uncertainties to a very great extent, which in many cases are 4 times smaller than those obtained with uncorrelated data

[en] In the frameworks of the neutronics calculation schemes improvement and qualification, this thesis consists of the conception, the optimization and the development of γ-ray spectrometry techniques for the measurement of integral parameters, in the EOLE and MINERVE facilities. The work aims at correcting systematic errors and at controlling and reducing uncertainties on the measurement results. The achieved progresses allow a more precise comparison between calculations and experiments and a better knowledge of some nuclear data, especially integral capture and fission cross sections. Firstly, the former instrumentation - using an analog chain (2026 amplifier and PCA3 converter / analyser) - has been fully tested to estimate the experimental errors on the determination of neutronics parameters. This work shows a systematic bias up to 12% on the measurement of the power distribution scaling factor and up to 3% on the measurement of the axial buckling, due to the lack of pulse pile-up correction. Following a comparative study, these electronics have been replaced by a digital DSP2060 system with an adapted dead time correction. With the optimization of its parameters, a precision at better than 0.5% has been achieved until a 1.5*10⁵ s^-1 count rate. Consequently, this work allows new kinds of experiments, which could not have been done with a sufficient precision by the past. Secondly, the former methods applied to the treatment of measurement raw data and to the variance propagation, have been analysed and discussed. Different systematic errors, which were not taken into account by the past, are now corrected. They concern the influence of the activity decay on the dead time correction (about 2%), the true coincidence effect (about 5%) and the solid angle effect on the efficiency transfer corrections (about 8%). Besides, the description of more precise methods for the variance propagation leads to a 3 times better uncertainty on fundamental neutronics parameters - scaling factor on power distributions (about 0.6%) and axial buckling (about 0.7%) - and a 2 times better uncertainty on the measurement of the uranium 238 conversion ratio (about 1.5%). These progresses have been applied to the conception of experiments in support to the qualification of cross sections, for actinides (²³²Th, ²³⁶U, ²³⁷Np, ²⁴²Pu) and neutron absorbers (¹⁵¹Eu, ¹⁵³Eu, ¹⁶⁴Dy, ¹⁷⁰Er, ¹⁸⁰Hf). The comparison of capture cadmium ratio and capture index measurements, with APOLLO2 deterministic calculations or MCNP4C2 probabilistic calculations, with the JEF2.2, ENDF/B-VI.8 ore JEFF3.1 libraries, shows systematic biases on the integral capture cross sections up to 50% for certain isotopes, with an experimental uncertainty better than 2%. Lastly, experiments dedicated to the qualification of decay data have been carried out for the first time in the Experimental Program Laboratory (LPE) of CEA Cadarache. A systematic error of about 5% has been identified on the JEFF3.1 evaluation of the half-life of strontium 92. This nuclear data has been reevaluated with specific measurements, with a 2 times better uncertainty compared with the past. Fission yield fluctuations on the ²³⁵U(n,f) reaction have also been identified between a thermal and an epithermal neutronics spectra, from -0.8% to +2%. The study gives some recommendations on the calculation method to estimate the average fission yield, for under-moderated reactor concepts. (author)

[en] Since in modern nuclear data banks (such as JEFF-3.1.1 and ENDF/BVII.1) no correlations for fission yields are given, in the present work we propose a covariance generation methodology for fission product yields. The main goal is to reproduce the existing European library and to add covariance information to allow proper uncertainty propagation in depletion and decay heat calculations. To do so, we have adopted the Generalized Least Square Method (GLSM) implemented in CONRAD (Code for Nuclear Reaction Analysis and Data assimilation), developed at CEA-Cadarache. Theoretical values employed in the Bayesian parameter adjustment are delivered thanks to a convolution of different models, representing several quantities in fission yield calculations: the Brosa fission modes for pre-neutron mass distribution, a simplified Gaussian model for prompt neutron emission probability, the Wahl systematics for charge distribution and the Madland-England model for the isomeric ratio. Some results will be presented for the thermal fission of U-235, Pu-239 and Pu-241. (authors)