Detailed modeling of fission with $FREYA$

Journal Article · Mon Sep 24 00:00:00 EDT 2018 · Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment

DOI:https://doi.org/10.1016/j.nima.2018.09.060· OSTI ID:1515337

Vogt, R. ^[1]; Randrup, J. ^[2]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Nuclear and Chemical Sciences Division; Univ. of California, Davis, CA (United States). Physics Dept.
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Nuclear Science Division

For many years, the state of the art for treating fission in radiation transport codes has involved sampling from average distributions. However, such “average” fission models have limited interaction-by-interaction capabilities. Energy is not explicitly conserved and no correlations are available because all particles are emitted isotropically and independently. However, in a true fission event, the energies, momenta and multiplicities of emitted particles are correlated. Such correlations are interesting for many modern applications, including detector development and detection of small amounts of special material. Recently, several Monte Carlo codes have become available that calculate complete fission events. Event-by-event techniques are particularly useful because it is possible to obtain the fission products as well as the prompt neutrons and photons emitted during an individual fission process, all with complete kinematic information. It is therefore possible to extract any desired correlation observables. Such codes, when included in broader Monte Carlo transport codes, such as MCNP, can be made broadly available to the community. One such code, FREYA (Fission Reaction Event Yield Algorithm), is particularly fast and can readily generate large samples of complete fission events. We briefly describe here the physics in FREYA and compare our results with relevant available data on prompt neutron and photon emission. We discuss correlated measurements in particular for validation.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation
• Grant/Contract Number: AC52-07NA27344; AC02-05CH11231
• OSTI ID: 1515337
• Alternate ID(s): OSTI ID: 1636264
• Report Number(s): LLNL-JRNL-753800; 940436
• Journal Information: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 954, Issue C; ISSN 0168-9002
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

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