Influence of noncondensible gas on heat removal from the primary of a PWR
Under loss-of-coolant accident conditions, there is a possibility that noncondensible gas (i.e., nitrogen, hydrogen, or fission gas) will enter the primary system, which can adversely affect the capability to remove decay heat. Small- and medium-sized breaks cause depressurization and lead to release of N{sub 2} dissolved in the primary coolant and accumulator inventories. Failure to close of an accumulator isolation valve after the accumulator content has emptied into the primary can result in significant amounts of propellant gas entering the primary system. In the event of a total loss of on- and off-site power, the feedwater is also lost. With the main steam isolation valves close, the secondaries boil dry through relief valves. The core decay heat leads to pressurization of the primary system, opening of the pressurizer safety relief valve, and loss of primary inventory. Without operator intervention, this scenario results in core uncovery and core damage as the primary inventory is depleted. At temperatures >800{degree}C (1500{degree}F), zircon/water reaction will take place accompanied by formation of substantial amounts of hydrogen. At this stage, even restored heat transfer (e.g., resumption of feedwater flow) will be impeded by the presence of the hydrogen. The influence of noncondensible gases on the heat transfer capability of a four-loop pressurized water reactor (PWR) was investigated in several parametric studies carried out in the PKL test facility.
- OSTI ID:
- 5822237
- Report Number(s):
- CONF-901101-; CODEN: TANSA
- Journal Information:
- Transactions of the American Nuclear Society; (USA), Vol. 62; Conference: American Nuclear Society (ANS) winter meeting, Washington, DC (USA), 11-15 Nov 1990; ISSN 0003-018X
- Country of Publication:
- United States
- Language:
- English
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HEAT TRANSFER
HYDRAULICS
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ACCUMULATORS
AFTER-HEAT REMOVAL
BLACKOUTS
FISSION PRODUCTS
HYDROGEN
NITROGEN
PARAMETRIC ANALYSIS
PRIMARY COOLANT CIRCUITS
REACTOR ACCIDENTS
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FLOW REGULATORS
FLUID FLOW
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ISOTOPES
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RADIOACTIVE MATERIALS
REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
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