Experimental study of PHWR debris bed under boil-off condition
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D. Mukhopadhyay
Abstract
Experiments have been carried out to study the heatup behavior of a submerged debris bed constituted of segmented reactor channels of Pressurized Heavy Water Reactors (PHWR). The study has been done for under fully submerged, partially submerged and nearly exposed conditions. This situation may arise from a severe accident scenario of PHWR where full or segmented reactor channels are likely to be disassembled and form a submerged debris bed. An assembly of electrical heater rod, simulating fuel bundle and channel components like Pressure tube and calandria tube constitute each segmented reactor channels. Ten such reactor channels constitute the debris bed. Heatup of this debris bed is observed with respect to different water levels and at power levels of 10, 20 and 30 kW, typical to decay power levels of 0.25 %, 0.5 % and 0.75 % of reactor full power respectively. It has been observed from the set of experiments that fully submerged debris bed does not get heated up and fuel rod temperature remains at saturation temperature. Heatup is observed for exposed channels only, however the heatup rate is limited with steam and radiative cooling. For exposed debris bed, channels surrounded by neighboring channels get heated up as compared to channels at the periphery of the debris bed.
Kurzfassung
Experimente zur Untersuchung des Aufheizverhaltens eines unter Wasser befindlichen Trümmerbettes bestehend aus mehrteiligen Kanälen eines Druckwasserreaktors wurden durchgeführt. Die Studie wurde unter folgenden Bedingungen durchgeführt: ganz unter Wasser, teilweise unter Wasser und fast ganz exponiert. Diese Situationen können in Szenarien schwerer Unfälle bei PHWR auftreten, wenn Kanäle im Reaktor zerlegt werden und ein Trümmerbett bilden. Eine Anordnung von Elektroheizstäben, die ein Brennstoffbündel simulieren, und Kanalkomponenten wie Druckröhren und Calandria-Röhren stellen jeweils mehrteilige Kanäle dar. Zehn solcher Kanäle bilden ein Trümmerbett. Die Aufheizung dieses Trümmerbettes wurde beobachtet bei verschiedenen Wasserständen und bei Leistungen von 10, 20 and 30 kW, typisch für sinkende Leistungen von 0,25 %, 0,5 % und 0,75 % der vollen Reaktorleistung. Dabei wurde beobachtet, dass ein vollständig unter Wasser befindliches Trümmerbett sich nicht aufheizt und die Brennelemente Sättigungstemperatur haben. Aufheizung wird nur bei exponierten Kanälen beobachtet. Die Aufheizgeschwindigkeit wird jedoch begrenzt durch Dampfkühlung und Strahlungskühlung. Beim exponierten Trümmerbett erhitzen sich Kanäle umgeben von benachbarten Kanälen eher als die am Rand befindlichen.
References
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© 2014, Carl Hanser Verlag, München
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Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Analysis of processes in RBMK-1500 fuel rods during the operation, short and intermediate term storage
- Can mechanical stresses noticeably influence the diffusion of hydrogen in zircaloy?
- Out-of-pile modelling of nuclear fuel elements for MTR type reactors – Part 1
- Experimental study of PHWR debris bed under boil-off condition
- Effectiveness of radial flow on rewetting of AHWR fuel cluster
- Radiotracers in performance evaluation of nuclear grade resins Amberlite IRN-78 and Purolite NRW-8000
- The production of 238–242Pu(n,γ)239–243Pu fissionable fluids in a fusion-fission hybrid reactor
- Theoretical study of deuteron induced reactions on 6,7Li, 9Be and 19F targets
- Upgrading of neutron radiography/tomography facility at research reactor
- Assessment of the radiological health damage costs of the Yeniköy and Kemerköy lignite-fired power plants in Muğla
