Introducing the SLICE Method for estimating pebble-bed reactor inventories at equilibrium operation with SCALE

Friederike Bostelmann; Steven E. Skutnik; William A. Wieselquist

doi:10.1016/j.anucene.2025.111684

Introducing the SLICE Method for estimating pebble-bed reactor inventories at equilibrium operation with SCALE

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3 Scopus citations

Abstract

This paper introduces the SCALE Leap-In method for Cores at Equilibrium (SLICE) for estimating pebble-bed reactor equilibrium core isotopic inventories using capabilities in the SCALE code system, requiring only a small computational cluster and a few days of computation. This method uses an iterative approach that relies on (1) a surrogate spectrum model that captures spatial and time-dependent spectral conditions, (2) a multi-pass model that captures the pebble's evolving nuclide inventory as a function of location and time in the core, and (3) a full-core model that captures the core's spatial neutron flux distribution. The SLICE approach is applied to a generic fluoride salt–cooled high-temperature reactor, demonstrating fuel inventory convergence through nuclide concentration inspection across iterations and comparisons for core realizations with varying discretizations. Results agree within ∼5% with another state-of-the-art code, with differences attributed to input parameter or modeling assumption variations in the equilibrium generation methods.

Original language	English
Article number	111684
Journal	Annals of Nuclear Energy
Volume	224
DOIs	https://doi.org/10.1016/j.anucene.2025.111684
State	Published - Dec 15 2025

Funding

The initial development of SLICE was sponsored by the US Nuclear Regulatory Commission’s Office of Nuclear Reactor Regulation and Office of Nuclear Regulatory Research . Later modifications were funded by the US Department of Energy, Office of Science , Nuclear Data Program. The authors thank the individuals who have tested the SLICE method in its various stages of development: Annie Berens, Nicholas R. Brown, Rabab Elzohery, Donny Hartanto, Robert F. Kile, and Zoe Richter. The initial development of SLICE was sponsored by the US Nuclear Regulatory Commission's Office of Nuclear Reactor Regulation and Office of Nuclear Regulatory Research. Later modifications were funded by the US Department of Energy, Office of Science, Nuclear Data Program. The authors thank the individuals who have tested the SLICE method in its various stages of development: Annie Berens, Nicholas R. Brown, Rabab Elzohery, Donny Hartanto, Robert F. Kile, and Zoe Richter.

Keywords

Equilibrium core
Inventory generation
Pebble-bed reactor
SCALE
gFHR

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10.1016/j.anucene.2025.111684

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title = "Introducing the SLICE Method for estimating pebble-bed reactor inventories at equilibrium operation with SCALE",

abstract = "This paper introduces the SCALE Leap-In method for Cores at Equilibrium (SLICE) for estimating pebble-bed reactor equilibrium core isotopic inventories using capabilities in the SCALE code system, requiring only a small computational cluster and a few days of computation. This method uses an iterative approach that relies on (1) a surrogate spectrum model that captures spatial and time-dependent spectral conditions, (2) a multi-pass model that captures the pebble's evolving nuclide inventory as a function of location and time in the core, and (3) a full-core model that captures the core's spatial neutron flux distribution. The SLICE approach is applied to a generic fluoride salt–cooled high-temperature reactor, demonstrating fuel inventory convergence through nuclide concentration inspection across iterations and comparisons for core realizations with varying discretizations. Results agree within ∼5\% with another state-of-the-art code, with differences attributed to input parameter or modeling assumption variations in the equilibrium generation methods.",

keywords = "Equilibrium core, Inventory generation, Pebble-bed reactor, SCALE, gFHR",

author = "Friederike Bostelmann and Skutnik, \{Steven E.\} and Wieselquist, \{William A.\}",

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AU - Bostelmann, Friederike

AU - Skutnik, Steven E.

AU - Wieselquist, William A.

PY - 2025/12/15

Y1 - 2025/12/15

N2 - This paper introduces the SCALE Leap-In method for Cores at Equilibrium (SLICE) for estimating pebble-bed reactor equilibrium core isotopic inventories using capabilities in the SCALE code system, requiring only a small computational cluster and a few days of computation. This method uses an iterative approach that relies on (1) a surrogate spectrum model that captures spatial and time-dependent spectral conditions, (2) a multi-pass model that captures the pebble's evolving nuclide inventory as a function of location and time in the core, and (3) a full-core model that captures the core's spatial neutron flux distribution. The SLICE approach is applied to a generic fluoride salt–cooled high-temperature reactor, demonstrating fuel inventory convergence through nuclide concentration inspection across iterations and comparisons for core realizations with varying discretizations. Results agree within ∼5% with another state-of-the-art code, with differences attributed to input parameter or modeling assumption variations in the equilibrium generation methods.

AB - This paper introduces the SCALE Leap-In method for Cores at Equilibrium (SLICE) for estimating pebble-bed reactor equilibrium core isotopic inventories using capabilities in the SCALE code system, requiring only a small computational cluster and a few days of computation. This method uses an iterative approach that relies on (1) a surrogate spectrum model that captures spatial and time-dependent spectral conditions, (2) a multi-pass model that captures the pebble's evolving nuclide inventory as a function of location and time in the core, and (3) a full-core model that captures the core's spatial neutron flux distribution. The SLICE approach is applied to a generic fluoride salt–cooled high-temperature reactor, demonstrating fuel inventory convergence through nuclide concentration inspection across iterations and comparisons for core realizations with varying discretizations. Results agree within ∼5% with another state-of-the-art code, with differences attributed to input parameter or modeling assumption variations in the equilibrium generation methods.

KW - Equilibrium core

KW - Inventory generation

KW - Pebble-bed reactor

KW - SCALE

KW - gFHR

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M1 - 111684

ER -

Introducing the SLICE Method for estimating pebble-bed reactor inventories at equilibrium operation with SCALE

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