Special Section Papers

Collapse Criterion for the CANDU 6 Calandria Vault Floor During a Severe Accident

[+] Author and Article Information
Robert David

Canadian Nuclear Laboratories,
286 Plant Road,
Chalk River, ON K0J 1J0, Canada
e-mail: robert.david@cnl.ca

Manuscript received July 7, 2016; final manuscript received November 22, 2016; published online March 1, 2017. Assoc. Editor: Arun Nayak.

ASME J of Nuclear Rad Sci 3(2), 020908 (Mar 01, 2017) (6 pages) Paper No: NERS-16-1065; doi: 10.1115/1.4035336 History: Received July 07, 2016; Revised November 22, 2016

The thickness at which the calandria vault floor in a generic CANDU 6 nuclear reactor may collapse while undergoing molten core–concrete interaction (MCCI) was studied using an approximate analytical model and a finite-element model. It was confirmed that the collapse criterion of 0.45 m floor thickness that is currently used in severe accident analyses is adequate. The estimated timing of collapse is subject to uncertainty of several hours.

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Fig. 1

Model of the calandria vault floor

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Fig. 2

Results from the analytical model (see online figure for color)

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Fig. 3

Thermal boundary conditions for the finite-element model

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Fig. 4

Calculated temperatures from the finite-element model (see online figure for color)

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Fig. 5

Temperature at the bottom of the floor (see online figure for color)

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Fig. 6

Stress at the center of the bottom of the floor (see online figure for color)

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Fig. 7

Results of the finite-element analysis without thermal expansion (see online figure for color)

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Fig. 8

Stress indicative of cracking beneath the melting front (see online figure for color)

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Fig. 9

Results of the finite-element model with thermal expansion (see online figure for color)




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