Identification of open issues in the UCTD model and proposed improvements for uses in licensing

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Identification of open issues in the UCTD model and proposed improvements for uses in licensing. / Pacio, Julio; Chen, Shih-Kuei; Chen, Yu-Min; Todreas, Neil.

NURETH-19 - 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics: Brussels, Belgium, March 6 – 11, 2022. ANS - American Nuclear Society, 2022. p. 1-16 34453.

Research output: Contribution to report/book/conference proceedingsIn-proceedings paperpeer-review

Harvard

Pacio, J, Chen, S-K, Chen, Y-M & Todreas, N 2022, Identification of open issues in the UCTD model and proposed improvements for uses in licensing. in NURETH-19 - 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics: Brussels, Belgium, March 6 – 11, 2022., 34453, ANS - American Nuclear Society, pp. 1-16. <https://www.ans.org/pubs/proceedings/page-2/>

APA

Pacio, J., Chen, S-K., Chen, Y-M., & Todreas, N. (2022). Identification of open issues in the UCTD model and proposed improvements for uses in licensing. In NURETH-19 - 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics: Brussels, Belgium, March 6 – 11, 2022 (pp. 1-16). [34453] ANS - American Nuclear Society. https://www.ans.org/pubs/proceedings/page-2/

Vancouver

Pacio J, Chen S-K, Chen Y-M, Todreas N. Identification of open issues in the UCTD model and proposed improvements for uses in licensing. In NURETH-19 - 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics: Brussels, Belgium, March 6 – 11, 2022. ANS - American Nuclear Society. 2022. p. 1-16. 34453

Author

Pacio, Julio ; Chen, Shih-Kuei ; Chen, Yu-Min ; Todreas, Neil. / Identification of open issues in the UCTD model and proposed improvements for uses in licensing. NURETH-19 - 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics: Brussels, Belgium, March 6 – 11, 2022. ANS - American Nuclear Society, 2022. pp. 1-16

Bibtex - Download

@inproceedings{626b0f154f4c4e0c8bc6975c1e917d57,
title = "Identification of open issues in the UCTD model and proposed improvements for uses in licensing",
abstract = "Fuel assemblies in liquid-metal cooled reactors often utilize a hexagonal array of pins with wire spacers helically wrapped around each pin. This classical rod bundle geometry is defined by six parameters: the number of rods, rod and wire diameters, pitch, wire lead and edge pitch. Since the 1960s many pressure loss tests have been performed in many countries, covering wide ranges of these parameters. Several authors also measured the flow velocities in the subchannels, i.e. the so-called flow-split. Making use of this database, the Upgraded Cheng and Todreas Detailed (UCTD) model described the friction losses in each subchannel individually and derives the bulk friction factor and flow split. UCTD predicts most friction data within 10% and reduces smoothly to bare bundle results if the wire diameter is set to zero. In this work, some features of the UCTD model are revised in order to address newly identified user needs relevant for uses in the context of licensing. In particular, UCTD consistently over-predicts the available data for flow velocity in the edge sub-channels. This is addressed by incorporating an additional physical mechanism of momentum exchange due to flow mixing. The new model, here called Pacio-Chen-Todreas detailed model (PCTD), smoothly reduces to UCTD if the mixing coefficients are set to zero. A best fitting set of empirical parameters is obtained by calibration using an extensive experimental database. PCTD can predict the bulk friction factor slightly better than UCTD, even with fewer non-zero empirical parameters. Moreover, PCTD provides an accurate prediction of the edge flow split. This feature is important for calculating scenarios, which cannot be compared directly with experiments, as in the context of licensing.",
keywords = "Rod bundle, Wire spacer, Pressure losses",
author = "Julio Pacio and Shih-Kuei Chen and Yu-Min Chen and Neil Todreas",
note = "Score=3",
year = "2022",
month = mar,
day = "6",
language = "English",
pages = "1--16",
booktitle = "NURETH-19 - 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics",
publisher = "ANS - American Nuclear Society",
address = "United States",

}

RIS - Download

TY - GEN

T1 - Identification of open issues in the UCTD model and proposed improvements for uses in licensing

AU - Pacio, Julio

AU - Chen, Shih-Kuei

AU - Chen, Yu-Min

AU - Todreas, Neil

N1 - Score=3

PY - 2022/3/6

Y1 - 2022/3/6

N2 - Fuel assemblies in liquid-metal cooled reactors often utilize a hexagonal array of pins with wire spacers helically wrapped around each pin. This classical rod bundle geometry is defined by six parameters: the number of rods, rod and wire diameters, pitch, wire lead and edge pitch. Since the 1960s many pressure loss tests have been performed in many countries, covering wide ranges of these parameters. Several authors also measured the flow velocities in the subchannels, i.e. the so-called flow-split. Making use of this database, the Upgraded Cheng and Todreas Detailed (UCTD) model described the friction losses in each subchannel individually and derives the bulk friction factor and flow split. UCTD predicts most friction data within 10% and reduces smoothly to bare bundle results if the wire diameter is set to zero. In this work, some features of the UCTD model are revised in order to address newly identified user needs relevant for uses in the context of licensing. In particular, UCTD consistently over-predicts the available data for flow velocity in the edge sub-channels. This is addressed by incorporating an additional physical mechanism of momentum exchange due to flow mixing. The new model, here called Pacio-Chen-Todreas detailed model (PCTD), smoothly reduces to UCTD if the mixing coefficients are set to zero. A best fitting set of empirical parameters is obtained by calibration using an extensive experimental database. PCTD can predict the bulk friction factor slightly better than UCTD, even with fewer non-zero empirical parameters. Moreover, PCTD provides an accurate prediction of the edge flow split. This feature is important for calculating scenarios, which cannot be compared directly with experiments, as in the context of licensing.

AB - Fuel assemblies in liquid-metal cooled reactors often utilize a hexagonal array of pins with wire spacers helically wrapped around each pin. This classical rod bundle geometry is defined by six parameters: the number of rods, rod and wire diameters, pitch, wire lead and edge pitch. Since the 1960s many pressure loss tests have been performed in many countries, covering wide ranges of these parameters. Several authors also measured the flow velocities in the subchannels, i.e. the so-called flow-split. Making use of this database, the Upgraded Cheng and Todreas Detailed (UCTD) model described the friction losses in each subchannel individually and derives the bulk friction factor and flow split. UCTD predicts most friction data within 10% and reduces smoothly to bare bundle results if the wire diameter is set to zero. In this work, some features of the UCTD model are revised in order to address newly identified user needs relevant for uses in the context of licensing. In particular, UCTD consistently over-predicts the available data for flow velocity in the edge sub-channels. This is addressed by incorporating an additional physical mechanism of momentum exchange due to flow mixing. The new model, here called Pacio-Chen-Todreas detailed model (PCTD), smoothly reduces to UCTD if the mixing coefficients are set to zero. A best fitting set of empirical parameters is obtained by calibration using an extensive experimental database. PCTD can predict the bulk friction factor slightly better than UCTD, even with fewer non-zero empirical parameters. Moreover, PCTD provides an accurate prediction of the edge flow split. This feature is important for calculating scenarios, which cannot be compared directly with experiments, as in the context of licensing.

KW - Rod bundle

KW - Wire spacer

KW - Pressure losses

UR - https://ecm.sckcen.be/OTCS/llisapi.dll/open/46984763

M3 - In-proceedings paper

SP - 1

EP - 16

BT - NURETH-19 - 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics

PB - ANS - American Nuclear Society

ER -

ID: 7335540