A non-fueled nuclear-heated rod for in-pile transient boiling studies

Journal Article · Sat Aug 05 00:00:00 EDT 2023 · Nuclear Engineering and Design

DOI:https://doi.org/10.1016/j.nucengdes.2023.112508· OSTI ID:2001104

Hill, Connie M. ^[1]; Folsom, Charles P. ^[1]; Fleming, Austin D. ^[1]; Armstrong, Robert J. ^[1]; Woolstenhulme, Nicolas E. ^[1]; Fishler, Joshua D. ^[1]; Bess, John D. ^[2]; Hernandez, Richard ^[3]; Brown, Nicholas R. ^[3]; Jensen, Colby B. ^[1]

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1. Idaho National Laboratory (INL), Idaho Falls, ID (United States)
2. Organisation for Economic Co-operation and Development (OECD), Paris (France). Nuclear Energy Agency (NEA)
3. Univ. of Tennessee, Knoxville, TN (United States)

Separate-effects boiling experiments have recently been conducted in the Transient Reactor Test Facility at Idaho National Laboratory to investigate transient heating and irradiation effects on cladding-to-coolant heat transfer. Specifically, transient critical heat flux (CHF) remains an important area of research, and better understanding of this phenomenon has potential for improving predictive models related to operational and safety limits. Consequently, this knowledge is expected to improve efficiency of light-water reactor operations. A novel borated nuclear-heated rodlet (BNHR) was designed to enable observation of transient cladding-to-coolant heat transfer phenomena. The final BNHR design takes a surrogate approach, wherein nuclear heating is induced by ¹⁰B(n, α) reactions rather than derived from fissions in a fueled specimen. The structure of the BNHR consists of a hollowed out borated (B_nat ~ 2.05 wt %) stainless steel tube with an hourglass-shaped outer surface, capped at both ends with non-borated stainless steel. This geometry allows for inner-rodlet instrumentation and generation of the highest nuclear heating rates near the center of the rodlet to ensure onset of boiling near instrumentation for real-time observation. A novel approach to measuring the nuclear energy deposition rate in the BNHR separate and apart from the influence of the coolant, termed the n-a thermometer, is also detailed in this paper. This device has demonstrated excellent repeatability, and measurements indicate predictive modeling results for energy deposition in the BNHR rod agree within a 10% margin of the experiment measurements. In conclusion, these results give confidence that the BNHR design has successfully met experiment objectives.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Nuclear Energy (NE)
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 2001104
• Report Number(s): INL/JOU--22-65784-Rev000
• Journal Information: Nuclear Engineering and Design, Journal Name: Nuclear Engineering and Design Vol. 414; ISSN 0029-5493
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

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