In this work, a case of loss of heat removal, caused by a loss of electrical supply, is analyzed for Atucha II PHWR. This reactor is similar to a PWR reactor in many aspects, but differs because it has, inside the pressure vessel, vertical coolant channels inside a moderator tank, which is at primary system pressure but a lower temperature. During the studied event, moderator temperature rises, heated by primary system (acting as a heat sink), until the temperatures are equalized. Given that primary and moderator systems are interconnected, the expansion of the moderator produces a rise in the level in pressurizer. The main aspects of the plant dynamic in the presented case are shown and analyzed. The normal strategy of the plant to cope with this initiating event is also discussed: the systems involved, operational modes and trigger signals are described. Then, three possible sequences are studied: heat removal by steam generators or moderator heat exchangers, and black out (no heat removal). The safety functions required to cope with this initiating event are also determined, as long as the associated safety and auxiliary systems. Representative variables of selected sequences are shown, in order to go further in understanding of the plant behavior. The different final stages are identified. The minimum capability of each system, necessary to achieve a plant safe condition, is also established. It was found that in this particular event, their requirements are less than the ones specified in the design basis. Also the influence of moderator system thermal inertia on transients is determined as a distinctive characteristics of this reactor.
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17th International Conference on Nuclear Engineering
July 12–16, 2009
Brussels, Belgium
Conference Sponsors:
- Nuclear Engineering Division
ISBN:
978-0-7918-4352-9
PROCEEDINGS PAPER
Analysis and Characterization of Sequences in Atucha II PHWR
Pablo Zanocco,
Pablo Zanocco
Comisio´n Nacional de Energi´a Ato´mica, Bariloche, Ri´o Negro, Argentina
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Jose´ Gonzalez,
Jose´ Gonzalez
Comisio´n Nacional de Energi´a Ato´mica, Bariloche, Ri´o Negro, Argentina
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Marcelo Gime´nez
Marcelo Gime´nez
Comisio´n Nacional de Energi´a Ato´mica, Bariloche, Ri´o Negro, Argentina
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Pablo Zanocco
Comisio´n Nacional de Energi´a Ato´mica, Bariloche, Ri´o Negro, Argentina
Jose´ Gonzalez
Comisio´n Nacional de Energi´a Ato´mica, Bariloche, Ri´o Negro, Argentina
Marcelo Gime´nez
Comisio´n Nacional de Energi´a Ato´mica, Bariloche, Ri´o Negro, Argentina
Paper No:
ICONE17-75364, pp. 487-494; 8 pages
Published Online:
February 25, 2010
Citation
Zanocco, P, Gonzalez, J, & Gime´nez, M. "Analysis and Characterization of Sequences in Atucha II PHWR." Proceedings of the 17th International Conference on Nuclear Engineering. Volume 2: Structural Integrity; Safety and Security; Advanced Applications of Nuclear Technology; Balance of Plant for Nuclear Applications. Brussels, Belgium. July 12–16, 2009. pp. 487-494. ASME. https://doi.org/10.1115/ICONE17-75364
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