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A study on transient heat transfer of the EU-ABWR external core catcher using the Phase-change Effective Convectivity Model
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2015 (English)In: International Topical Meeting on Nuclear Reactor Thermal Hydraulics 2015, NURETH 2015, American Nuclear Society, 2015, 6821-6834 p.Conference paper (Refereed)Text
Abstract [en]

In advanced designs of Nuclear Power Plants (NPPs), for mitigation of severe accident consequences, on the one hand, the In-Vessel Retention (IVR) concept has been implemented. On the other hand in other new NPP designs (Generation HI and III+) with large power reactors, the External Core Catcher (ECC) has been widely adopted. Assessment of ECC design robustness is largely based on analysis of heat transfer of a melt pool formed in the ECC. Transient heat transfer analysis of an ECC is challenging due to (i) uncertainty in the in-vessel accident progression and subsequent vessel failure modes; (ii) long transient, (iii) high Rayleigh number and complex flows involving phase change of the melt pool formed in an ECC. The present paper is concerned with analysis of transient melt pool heat transfer in the ECC of new Advanced Boiling Water Reactor (ABWR) designed by Toshiba Corporation (Japan). According to the ABWR severe accident management strategy, the ECC is initially dry. In order to prevent steam explosion flooding is initiated after termination of melt relocation from the vessel. The ECC full of melt is cooled from the top directly by water and from the bottom through the ECC walls. In order to assess sustainability of the ECC, heat transfer simulation of a stratified melt pool formed in the ECC is carried out. The problem addressed in this work is heat flux distribution at ECC boundaries when cooling is applied (i) from the bottom, (ii) from the top and from the bottom. To perform melt pool heat transfer simulation, we employ Phase-change Effective Convectivity Model (PECM) which was originally developed as a computationally efficient, sufficiently accurate, 2D/3D accident analysis tools for simulation of transient melt pool heat transfer in the reactor lower plenum. Thermal loads from the melt pool to ECC boundaries are determined for selected ex-vessel accident scenarios. Performance of the ECC, efficiency of severe accident management (SAM) measures and procedures are evaluated based on results of PECM simulation and severe accident analysis.

Place, publisher, year, edition, pages
American Nuclear Society, 2015. 6821-6834 p.
Keyword [en]
Core catcher, Heat transfer, Severe accident, Severe accident management (SAM), Accident prevention, Accidents, Boiling water reactors, Design, Heat flux, Hydraulics, Lakes, Nuclear power plants, Nuclear reactor accidents, Nuclear reactors, Reactor cores, Uncertainty analysis, Advanced boiling water reactors, Computationally efficient, Core catchers, Heat flux distributions, Heat transfer simulation, Severe accident management, Transient heat transfer
National Category
Mechanical Engineering
URN: urn:nbn:se:kth:diva-187524ScopusID: 2-s2.0-84964063358ISBN: 9781510811843OAI: diva2:938023
16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015, 30 August 2015 through 4 September 2015

QC 20160616

Available from: 2016-06-16 Created: 2016-05-25 Last updated: 2016-06-16Bibliographically approved

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Kudinov, Pavel
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