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Research Papers

Results of Air Barbotage Experiments Simulating Two-Phase Flow in a CANDU End Shield During In-Vessel Retention

[+] Author and Article Information
Justin H. Spencer

Canadian Nuclear Laboratories,
Chalk River, ON K0J 1J0, Canada

Manuscript received July 20, 2016; final manuscript received November 30, 2016; published online March 1, 2017. Assoc. Editor: Srikumar Banerjee.

ASME J of Nuclear Rad Sci 3(2), 021008 (Mar 01, 2017) (10 pages) Paper No: NERS-16-1075; doi: 10.1115/1.4035566 History: Received July 20, 2016; Revised November 30, 2016

This paper presents the results of experimental investigations into two-phase mass transport in a coarse packed bed representing the Canada Deuterium Uranium (CANDU) end shield. This work contributes to understanding of phenomena impacting in-vessel retention (IVR) during postulated severe accidents in CANDU reactors. The air barbotage technique was used to represent boiling at the calandria tubesheet surface facing the inner cavity of the end shield. Qualitative observations of the near-wall two-phase region were made during air injection. In addition, flow visualization was carried out through the addition of dye to the water. Air flow rate, shielding ball diameter, and cavity dimensions were varied within relevant ranges; and the impact of these parameters on the near-wall region was identified. A brief review of the relevant knowledge base is presented, allowing demonstration of the applicability of the test parameters. The observed phenomena are compared to published results involving similar geometries with capillary porous media.

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Figures

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Fig. 1

CANDU reactor core (Reproduced from Meneley and Ruan [1].)

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Fig. 2

Experimental apparatus: (a) full apparatus frame and (b) cutaway view

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Fig. 3

Pool boiling photographs at increasing heat fluxes for a thin, vertically oriented heater (Reproduced from Howard and Mudawar [26].)

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Fig. 4

Tests in the absence of shielding balls

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Fig. 5

Tests with 9.5 mm shielding balls

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Fig. 6

Minimum thickness of two-phase region versus elevation-9.5 mm shielding balls

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Fig. 7

Maximum thickness of two-phase region versus elevation-9.5 mm shielding balls

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Fig. 8

Minimum thickness of two-phase region versus equivalent heat flux-9.5 mm shielding balls

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Fig. 9

Maximum thickness of two-phase region versus equivalent heat flux-9.5 mm shielding balls

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Fig. 10

Tests with 11.1 mm shielding balls

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Fig. 11

Minimum thickness of two-phase region versus equivalent heat flux-11.1 mm shielding balls

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Fig. 12

Maximum thickness of two-phase region versus equivalent heat flux-11.1 mm shielding balls

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Fig. 13

Tests with 12.7 mm shielding balls

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Fig. 14

Minimum thickness of two-phase region versus equivalent heat flux-12.7 mm shielding balls

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Fig. 15

Maximum thickness of two-phase region versus equivalent heat flux-12.7 mm shielding balls

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Fig. 16

Tests with 9.5 mm shielding balls and cavity thickness reduced to 197 mm

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Fig. 17

Tests with 9.5 mm shielding balls and cavity thickness reduced to 96 mm

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Fig. 18

Flow visualization test

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