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Special Section Papers

Analysis of Late Phase Severe Accident Phenomena in CANDU Plant

[+] Author and Article Information
D. Dupleac

Power Plant Engineering Faculty,
Politehnica University,
313 Splaiul Independentei, Sector 6,
Bucharest 060042, Romania
e-mail: danieldu@cne.pub.ro

Manuscript received July 30, 2016; final manuscript received December 5, 2016; published online March 1, 2017. Assoc. Editor: Arun Nayak.

ASME J of Nuclear Rad Sci 3(2), 020904 (Mar 01, 2017) (8 pages) Paper No: NERS-16-1085; doi: 10.1115/1.4035416 History: Received July 30, 2016; Revised December 05, 2016

The paper overviews the analytical studies performed at Politehnica University of Bucharest on the analysis of late phase severe accident phenomena in a Canada Deuterium Uranium (CANDU) plant. The calculations start from a dry debris bed at the bottom of calandria vessel. Both SCDAPSIM/RELAP code and ansys-fluent computational fluid dynamics (CFD) code are used. Parametric studies are performed in order to quantify the effect of several identified sources of uncertainty on calandria vessel failure: metallic fraction of zirconium inside the debris, containment pressure, timing of water depletion inside calandria vessel, steam circulation in calandria vessel above debris bed, debris temperature at moment of water depletion inside calandria vessel, calandria vault nodalization, and the gap heat transfer coefficient.

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References

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Figures

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Fig. 1

Terminal debris bed formed on CV bottom, externally cooled by calandria vault water

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Fig. 2

Nodalization of the in-vessel retention model

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Fig. 3

Debris bed temperature

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Fig. 4

Molten fraction of the debris

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Fig. 5

Calandria vault water level

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Fig. 6

Temperature of the bottom calandria vessel wall

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Fig. 7

Variation of the time of the CV failure time with the mass fraction of oxidized zirconium (for area of steam circulation above debris 0.5 m and heat transfer coefficient in the gap between debris and CV = 500 W/m2K)

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Fig. 8

Variation of the time of the CV failure time with the gap heat transfer coefficient (for area of steam circulation above debris 0.5 m and 100% mass fraction of oxidized zirconium)

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Fig. 9

Variation of the CV wall maximum heat flu with the mass fraction of oxidized zirconium (for area of steam circulation above debris 0.5 m and heat transfer coefficient in the gap between debris and CV = 500 W/m2K)

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Fig. 10

Variation of the CV wall rupture angle with the mass fraction of oxidized zirconium (for area o steam circulation above debris 0.5 m and heat transfer coefficient in the gap between debris and CV = 500 W/m2K)

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Fig. 11

Maximum calandria vessel wall heat flux

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Fig. 12

Maximum external calandria vessel wall heat flux

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Fig. 13

Temperature distribution on debris centreline at t = 8.3 h

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Fig. 14

Maximum value of calandria wall heat flux

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Fig. 15

Downward heat flux profile

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