SEFOR Model Description

The Southwest Experimental Fast Oxide Reactor (SEFOR) was an experimental sodium-cooled fast breeder reactor operated from 1969 to 1972 with maximum power up to 20 MWt (Meyer et al., 1969). It was a pool-type sodium fast reactor (SFR) fueled with mixed UO $var element = document.getElementById("moose-equation-c428aba6-4129-432a-8c4f-e734936c023f");katex.render("2", element, {displayMode:false,throwOnError:false});$ -PuO $var element = document.getElementById("moose-equation-b1c6d7c2-292d-409d-8046-30111661d28e");katex.render("2", element, {displayMode:false,throwOnError:false});$ (MOX). The reactor core was housed in the concrete-shielded nitrogen-atmosphere within a reactor building. Core criticality was controlled by ten movable nickel reflectors positioned outside the reactor vessel, moving vertically. For shutdown, all reflectors were pushed down below the reactor fuel region. During normal operations, two reflector positions were adjusted to fine-tune core criticality while the others were either down below the active core or fully up to cover the reactor fuel region.

During the SEFOR operation period, a three-phase experimental program was carried out to measure the Doppler reactivity feedback under various reactor conditions: Phase I - reactor startup and zero-power tests(Noble et al., 1970), Phase II - steady state power ascending tests(Pflasterer and Becker, 1969), and Phase III - reactivity insertion transient tests(Noble et al., 1971). These experiments produced unique sets of measured Doppler reactivity feedback in a wide temperature range from around 350 °F to temperatures approaching the melting point of mixed oxide fuel of around 5000 °F, providing valuable data for code validations.

This document describes the MC $var element = document.getElementById("moose-equation-3ba05ac9-4561-41fe-9d5b-1edc04528b42");katex.render("^2", element, {displayMode:false,throwOnError:false});$ -3/Griffin models developed to simulate the SEFOR experimental tests. The MOOSE Reactor Module (Shemon et al., 2023) was used to set up the geometry mesh shown in the Mesh Model. Griffin (Wang et al., 2025) was used to calculate the neutronics shown in the Griffin Model. In addition, MC $var element = document.getElementById("moose-equation-e3f225c1-6a61-4451-ad45-09574dc3352e");katex.render("^2", element, {displayMode:false,throwOnError:false});$ -3 (Lee and Yang, 2017) was used to generate multigroup cross sections for Griffin calculations at different temperatures. Inputs for different SEFOR core configurations were included in the Cross Section. The Monte Carlo code Shift (Pandya et al., 2016) provided reference solutions for the Griffin deterministic results as described in the Shift Reference Model.

Numerical simulations to the different experimental tests conducted in the SEFOR during three experimental phases are included in the SEFOR Tests. Accuracies of these numerical models were assessed by comparing with SEFOR experimental data.

References

Changho Lee and Won Sik Yang. Mc2-3: multigroup cross section generation code for fast reactor analysis. Nuclear Science and Engineering, 187(3):268–290, 2017. URL: https://doi.org/10.1080/00295639.2017.1320893, doi:10.1080/00295639.2017.1320893.

@article{Lee2017sefor,
    author = "Lee, Changho and Yang, Won Sik",
    title = "MC2-3: Multigroup Cross Section Generation Code for Fast Reactor Analysis",
    journal = "Nuclear Science and Engineering",
    volume = "187",
    number = "3",
    pages = "268-290",
    ISSN = "0029-5639",
    DOI = "10.1080/00295639.2017.1320893",
    url = "https://doi.org/10.1080/00295639.2017.1320893",
    year = "2017",
    type = "Journal Article"
}

R A Meyer, A B Reynolds, S L Stewart, M L Johnson, and E R Craig. Design and analysis of sefor core i. Technical Report, General Electric Co., Sunnyvale, Calif. Breeder Reactor Development Operation, 12 1969. URL: https://www.osti.gov/biblio/4096432, doi:10.2172/4096432.

@techreport{Meyer1970sefor,
    author = "Meyer, R A and Reynolds, A B and Stewart, S L and Johnson, M L and Craig, E R",
    title = "DESIGN AND ANALYSIS OF SEFOR CORE I.",
    institution = "General Electric Co., Sunnyvale, Calif. Breeder Reactor Development Operation",
    annote = "",
    doi = "10.2172/4096432",
    url = "https://www.osti.gov/biblio/4096432",
    place = "United States",
    year = "1969",
    month = "12"
}

L D Noble, G Kussmaul, and S L Derby. Experimental program results in sefor core ii. Technical Report, General Electric Co., Sunnyvale, Calif. Breeder Reactor Dept., 12 1971. URL: https://www.osti.gov/biblio/4621121, doi:10.2172/4621121.

@techreport{Noble1971sefor,
    author = "Noble, L D and Kussmaul, G and Derby, S L",
    title = "EXPERIMENTAL PROGRAM RESULTS IN SEFOR CORE II.",
    institution = "General Electric Co., Sunnyvale, Calif. Breeder Reactor Dept.",
    annote = "",
    doi = "10.2172/4621121",
    url = "https://www.osti.gov/biblio/4621121",
    place = "United States",
    year = "1971",
    month = "12"
}

L. D. Noble, F. Mitzel, B. Sarma, D. Wintzer, Y. S. Lu, G. Kessler, G. R. Pflasterer, R. A. Becker, and L. Mansur. Results of sefor zero power experiements. Technical Report, General Electric Co., Sunnyvale, CA (United States), 02 1970. URL: https://www.osti.gov/biblio/4148916, doi:10.2172/4148916.

@techreport{Noble1970sefor,
    author = "Noble, L. D. and Mitzel, F. and Sarma, B. and Wintzer, D. and Lu, Y. S. and Kessler, G. and Pflasterer, G. R. and Becker, R. A. and Mansur, L.",
    title = "Results of SEFOR Zero Power Experiements",
    institution = "General Electric Co., Sunnyvale, CA (United States)",
    annote = "The SEFOR experimental program is comprised of a series of tests beginning with low power tests, proceeding through static and frequency response tests at various power levels up to full power, and culminating in a series of sub-prompt and super-prompt critical transients. The results of the low (zero) power tests are reported here and are compared with calculations. The agreement between experiment and calculation is generally good. The tests were conducted at low power and included such experiments as the approach to the minimum critical core size, calibration of the reflector control, measurement of fission rate distributions, material reactivity worth measurements, uniform non-nuclear heating of the reactor to determine the reactivity temperature coefficient, and the measurement of the ratio ($\ell$/β) of the prompt neutron lifetime to the effective delayed neutron fraction.",
    doi = "10.2172/4148916",
    url = "https://www.osti.gov/biblio/4148916",
    place = "United States",
    year = "1970",
    month = "02"
}

Tara M. Pandya, Seth R. Johnson, Thomas M. Evans, Gregory G. Davidson, Steven P. Hamilton, and Andrew T. Godfrey. Implementation, capabilities, and benchmarking of shift, a massively parallel monte carlo radiation transport code. Journal of Computational Physics, 308:239–272, 2016. URL: https://www.sciencedirect.com/science/article/pii/S0021999115008566, doi:https://doi.org/10.1016/j.jcp.2015.12.037.

@article{Pandya2016sefor,
    author = "Pandya, Tara M. and Johnson, Seth R. and Evans, Thomas M. and Davidson, Gregory G. and Hamilton, Steven P. and Godfrey, Andrew T.",
    title = "Implementation, capabilities, and benchmarking of Shift, a massively parallel Monte Carlo radiation transport code",
    journal = "Journal of Computational Physics",
    volume = "308",
    pages = "239-272",
    ISSN = "0021-9991",
    DOI = "https://doi.org/10.1016/j.jcp.2015.12.037",
    url = "https://www.sciencedirect.com/science/article/pii/S0021999115008566",
    year = "2016",
    type = "Journal Article"
}

G. R. Pflasterer and R. A. Becker. Southwest experimental fast oxide reactor development program. twenty- sixth quarterly report, august–october 1970. Technical Report, comps.; General Electric Co., Sunnyvale, Calif. Breeder Reactor Development Operation, 12 1969. URL: https://www.osti.gov/biblio/4018034, doi:10.2172/4018034.

@techreport{Pflasterer1969sefor,
    author = "Pflasterer, G. R. and Becker, R. A.",
    title = "SOUTHWEST EXPERIMENTAL FAST OXIDE REACTOR DEVELOPMENT PROGRAM. Twenty- Sixth Quarterly Report, August--October 1970.",
    institution = "comps.; General Electric Co., Sunnyvale, Calif. Breeder Reactor Development Operation",
    annote = "",
    doi = "10.2172/4018034",
    url = "https://www.osti.gov/biblio/4018034",
    place = "United States",
    year = "1969",
    month = "12"
}

Emily Shemon, Yinbin Miao, Shikhar Kumar, Kun Mo, Yeon Sang Jung, Aaron Oaks, Scott Richards, Guillaume Giudicelli, Logan Harbour, and Roy Stogner. Moose reactor module: an open-source capability for meshing nuclear reactor geometries. Nuclear Science and Engineering, 197(8):1656–1680, 2023. URL: https://doi.org/10.1080/00295639.2022.2149231, doi:10.1080/00295639.2022.2149231.

@article{Shemon2023sefor,
    author = "Shemon, Emily and Miao, Yinbin and Kumar, Shikhar and Mo, Kun and Jung, Yeon Sang and Oaks, Aaron and Richards, Scott and Giudicelli, Guillaume and Harbour, Logan and Stogner, Roy",
    title = "MOOSE Reactor Module: An Open-Source Capability for Meshing Nuclear Reactor Geometries",
    journal = "Nuclear Science and Engineering",
    volume = "197",
    number = "8",
    pages = "1656-1680",
    ISSN = "0029-5639",
    DOI = "10.1080/00295639.2022.2149231",
    url = "https://doi.org/10.1080/00295639.2022.2149231",
    year = "2023",
    type = "Journal Article"
}

Yaqi Wang, Zachary M. Prince, Hansol Park, Olin W. Calvin, Namjae Choi, Yeon Sang Jung, Sebastian Schunert, Shikhar Kumar, Joshua T. Hanophy, Vincent M. Labouré, Changho Lee, Javier Ortensi, Logan H. Harbour, and Jackson R. Harter. Griffin: a moose-based reactor physics application for multiphysics simulation of advanced nuclear reactors. Annals of Nuclear Energy, 211:110917, 2025. URL: https://www.sciencedirect.com/science/article/pii/S0306454924005802, doi:https://doi.org/10.1016/j.anucene.2024.110917.

@article{Wang2025sefor,
    author = "Wang, Yaqi and Prince, Zachary M. and Park, Hansol and Calvin, Olin W. and Choi, Namjae and Jung, Yeon Sang and Schunert, Sebastian and Kumar, Shikhar and Hanophy, Joshua T. and Labouré, Vincent M. and Lee, Changho and Ortensi, Javier and Harbour, Logan H. and Harter, Jackson R.",
    title = "Griffin: A MOOSE-based reactor physics application for multiphysics simulation of advanced nuclear reactors",
    journal = "Annals of Nuclear Energy",
    volume = "211",
    pages = "110917",
    ISSN = "0306-4549",
    DOI = "https://doi.org/10.1016/j.anucene.2024.110917",
    url = "https://www.sciencedirect.com/science/article/pii/S0306454924005802",
    year = "2025",
    type = "Journal Article"
}

References