Fission Chain Restart Theory
We present that fast nanosecond timescale neutron and gammaray counting can be performed with a (liquid) scintillator array. Fission chains in metal evolve over a timescale of tens of nanoseconds. If the metal is surrounded by moderator, neutrons leaking from the metal can thermalize and diffuse in the moderator. With finite probability, the diffusing neutrons can return to the metal and restart the fast fission chain. The timescale for this restart process is microseconds. A theory describing time evolving fission chains for metal surrounded by moderator, including this restart process, is presented. Finally, this theory is sufficiently simple for it to be implemented for realtime analysis.
 Authors:

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 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Publication Date:
 Report Number(s):
 LLNLJRNL704257
Journal ID: ISSN 00295639
 Grant/Contract Number:
 AC5207NA27344
 Type:
 Accepted Manuscript
 Journal Name:
 Nuclear Science and Engineering
 Additional Journal Information:
 Journal Volume: 188; Journal Issue: 1; Journal ID: ISSN 00295639
 Publisher:
 American Nuclear Society  Taylor & Francis
 Research Org:
 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 98 NUCLEAR DISARMAMENT, SAFEGUARDS AND PHYSICAL PROTECTION; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 97 MATHEMATICS AND COMPUTING; Mathematical modeling; fast neutron counting; gammaray counting
 OSTI Identifier:
 1438761
Kim, K. S., Nakae, L. F., Prasad, M. K., Snyderman, N. J., and Verbeke, J. M.. Fission Chain Restart Theory. United States: N. p.,
Web. doi:10.1080/00295639.2017.1340691.
Kim, K. S., Nakae, L. F., Prasad, M. K., Snyderman, N. J., & Verbeke, J. M.. Fission Chain Restart Theory. United States. doi:10.1080/00295639.2017.1340691.
Kim, K. S., Nakae, L. F., Prasad, M. K., Snyderman, N. J., and Verbeke, J. M.. 2017.
"Fission Chain Restart Theory". United States.
doi:10.1080/00295639.2017.1340691. https://www.osti.gov/servlets/purl/1438761.
@article{osti_1438761,
title = {Fission Chain Restart Theory},
author = {Kim, K. S. and Nakae, L. F. and Prasad, M. K. and Snyderman, N. J. and Verbeke, J. M.},
abstractNote = {We present that fast nanosecond timescale neutron and gammaray counting can be performed with a (liquid) scintillator array. Fission chains in metal evolve over a timescale of tens of nanoseconds. If the metal is surrounded by moderator, neutrons leaking from the metal can thermalize and diffuse in the moderator. With finite probability, the diffusing neutrons can return to the metal and restart the fast fission chain. The timescale for this restart process is microseconds. A theory describing time evolving fission chains for metal surrounded by moderator, including this restart process, is presented. Finally, this theory is sufficiently simple for it to be implemented for realtime analysis.},
doi = {10.1080/00295639.2017.1340691},
journal = {Nuclear Science and Engineering},
number = 1,
volume = 188,
place = {United States},
year = {2017},
month = {7}
}