Natural convection in a shallow pool heated from below and implications for the thermal focusing effect at the lateral wall

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F46356088%3A_____%2F25%3AN0000019" target="_blank" >RIV/46356088:_____/25:N0000019 - isvavai.cz</a>

Result on the web

<a href="https://www.sciencedirect.com/science/article/pii/S0029549324008033" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0029549324008033</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.nucengdes.2024.113703" target="_blank" >10.1016/j.nucengdes.2024.113703</a>

Result language

angličtina

Original language name

Natural convection in a shallow pool heated from below and implications for the thermal focusing effect at the lateral wall

Original language description

Convection within shallow pools of liquid metals heated from below is of significant interest for the In-Vessel Retention (IVR) strategy for Pressurised Water Reactors (PWR) as focusing of the lateral heat flux at the reactor wall presents a risk to the thermomechanical integrity of the reactor vessel. Under an IAEA Coordinated Research Project on corium melt retention, various international research institutions have performed CFD simulations to predict the thermal-hydraulic behaviour of a prototypic light metal layer of low Prandtl number (Pr = 0.02) and high external Rayleigh number (Ra Phi similar to 1012) dissipating heat from the free surface and at the lateral reactor wall. Various computational approaches including LES-WALE, LES-Smagorinsky and spectral-DNS were validated under the conditions of two BALI-Metal experiments in water (Pr = 6.9), revealing promising agreement in the predicted repartition of the heat flux at the vertical and lateral boundaries. Simulations in a prototypic light metal layer indicated 30-34 % of heat dissipation due to thermal radiation at the free surface. Average thermal losses at the lateral wall corresponded to a focusing effect of 3.3-3.7 times the imposed heat flux. A spike in lateral heat flux close to the free surface equated to a local focusing effect 6-times the imposed heat flux from below. The fluid dynamics, driven largely by thermal losses at the reactor wall, were characterised by downwards acceleration adjacent to the lateral wall and ejection of a cold jet parallel to the lower boundary, forming a large convection cell comparable in size to the radius of the reactor.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

20305 - Nuclear related engineering; (nuclear physics to be 1.3);

Project

—

Continuities

R - Projekt Ramcoveho programu EK

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Nuclear Engineering and Design

ISSN

0029-5493

e-ISSN

1872-759X

Volume of the periodical

431

Issue of the periodical within the volume

January

Country of publishing house

CH - SWITZERLAND

Number of pages

18

Pages from-to

1-18

UT code for WoS article

001361592900001

EID of the result in the Scopus database

2-s2.0-85209350550