Nuclear Data Evaluation For Plutonium 241

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ISBN 13 :
Total Pages : 38 pages
Book Rating : 4.:/5 (727 download)

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Download or read book Release of the 2008 Evaluated Nuclear Data Library (ENDL2008). written by and published by . This book was released on 2009 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Livermore's N-Division is now releasing the first version of a major new nuclear data library. This includes some 500 evaluations (roughly four times the number in the previous standard) and many physics improvements important for calculating weapon performance, output effects, attribution signatures, key radiochemical diagnostics and performance of conventional and hybrid fission/fusion reactors. As this library is more extensive and on a much firmer nuclear physics footing than the previous ENDL99 it should become, after a period of trial use by the applied community, the new standard for programmatic applications at Livermore. This work was supported by ASC-PEM and Campaign 4. Our basic philosophy in this release was to adopt the best work of the world's different nuclear data efforts. We have drawn heavily from the U.S. ENDF project (led by Brookhaven), the Japanese JENDL project (JAEA), and the European JEFF project (NEA). Because those efforts tend to focus on reactor applications they do not include an account of the charged particles emitted following a reaction. To enable broader applications we have used theory-based calculations to add a complete description of charged particles in all evaluations in the new library. This release also includes results from the last ten years of theory and experimental work here at Livermore. Some of the most important results include the surrogate campaign for unstable uranium isotopes, the LLNL/LANL 239Pu(n,2n) evaluation, the 241Am(n,2n) evaluation validated by the recent Livermore-led experiments, and measurements of 48Ti(n,2n). As well, we have adopted more than a hundred theory-based evaluations for radiochemical diagnostics completed by R. Hoffman and M. Mustafa and that use improved optical models, level densities, and decay scheme evaluations from the theory effort. These were extended to be transport complete (they now include a description of all of the particles emitted in reactions) to enable their use in neutronics simulations. There is an ongoing effort to provide all of these radiochemical evaluations, including isomers, in the next major ENDL release. The new library has undergone extensive unclassified testing. All isotopes were required to pass a set of simple tests with both deterministic and Monte Carlo codes to ensure that, at a minimum, they do not cause problems for the transport codes. As well, the data was validated through simulations of historical integral experiments. Calculations for k eigenvalues for a broad array of bare and reflected critical assemblies show a marked improvement over ENDL99 and performance comparable to or better than any other currently available library. In particular, there is now excellent agreement with results for the bare plutonium Jezebel assembly (k=1.0007). Similarly, simulations of photon production and neutron time of flight show, with some exceptions, excellent agreement with the LLNL pulsed sphere experiments. Our intention with this initial release is to engage the programmatic community to begin the process of testing with more complicated unclassified and classified problems. We would greatly appreciate recommendations and any reports of problems or oddities. These will be included in the final release of this database in 2009.