Masters Theses

Keywords and Phrases

Computer Simulation; Decay-Heat; Delayed-Particles; FMESH Reactor Source; MCNP; Pulse-Reactors


"Energy is deposited into experiment packages due to post-shutdown decay heat created from delayed particles. Modeling these delayed particles in a reactor assists researchers in quantifying the expected energy deposition sources to an experiment package before irradiation. This paper focuses on modeling the delayed particles in a reactor in MCNP6.2 by capturing a reactor as a source, converting this source capture to a source definition, applying appropriate physics such as activation and photonuclear interactions, and finally using proper tallies to create the expected delayed particle tail of a reactor.

To capture the source distribution, the FMESH capability within MCNP was used with the keyword TYPE set to SOURCE. To capture the energy distribution, an F4 tally with an E card would be applied to the reactor of interest to find the energy-dependent flux. The output MESHTAL of the FMESH and F4 tally results were then normalized and converted to a source definition. The ACT card within MCNP was utilized to create delayed particles and photonuclear interactions were turned on using the PHYS:P card. The F4 tally was utilized in tandem with T4 cards to model the time-dependent flux behavior within the reactor system which represents the delayed particle tail of the reactor.

This methodology was validated using compensating ion chamber detector data from the Missouri S&T Reactor (MSTR). The normalized trend of the MCNP F4 output agrees generally well with the normalized MSTR detector data and conservatively overestimates the normalized MSTR detector data, especially at later time bins"--Abstract page iii


Alajo, Ayodeji Babatunde

Committee Member(s)

Alam, Syed B.
Lum, Edward


Nuclear Engineering and Radiation Science

Degree Name

M.S. in Nuclear Engineering


This material is based upon work supported under a Department of Energy, Office of Nuclear Energy, Integrated University Program Graduate Fellowship.


Missouri University of Science and Technology

Publication Date

Summer 2022


xii, 63 pages

Note about bibliography

Includes bibliographic references (pages 61-62).


© 2022 Eli James Boland, All rights reserved.

Document Type

Thesis - Open Access

File Type




Thesis Number

T 12153

Electronic OCLC #