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Title: 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 heatmore » transfer capability of a four-loop pressurized water reactor (PWR) was investigated in several parametric studies carried out in the PKL test facility.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
5822237
Report Number(s):
CONF-901101--
Journal ID: ISSN 0003-018X; CODEN: TANSA
Resource Type:
Conference
Resource Relation:
Journal Name: Transactions of the American Nuclear Society; (USA); Journal Volume: 62; Conference: American Nuclear Society (ANS) winter meeting, Washington, DC (USA), 11-15 Nov 1990
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; LOSS OF COOLANT; HEAT TRANSFER; HYDRAULICS; PWR TYPE REACTORS; REACTOR SAFETY; AC SYSTEMS; ACCUMULATORS; AFTER-HEAT REMOVAL; BLACKOUTS; FISSION PRODUCTS; HYDROGEN; NITROGEN; PARAMETRIC ANALYSIS; PRIMARY COOLANT CIRCUITS; REACTOR ACCIDENTS; REACTOR CORES; RELIEF VALVES; TEST FACILITIES; TWO-PHASE FLOW; ACCIDENTS; CONTAINERS; CONTROL EQUIPMENT; COOLING SYSTEMS; ELEMENTS; ENERGY SYSTEMS; ENERGY TRANSFER; EQUIPMENT; FLOW REGULATORS; FLUID FLOW; FLUID MECHANICS; ISOTOPES; MATERIALS; MECHANICS; NONMETALS; POWER SYSTEMS; RADIOACTIVE MATERIALS; REACTOR COMPONENTS; REACTOR COOLING SYSTEMS; REACTORS; REMOVAL; SAFETY; TANKS; VALVES; WATER COOLED REACTORS; WATER MODERATED REACTORS 220900* -- Nuclear Reactor Technology-- Reactor Safety; 210200 -- Power Reactors, Nonbreeding, Light-Water Moderated, Nonboiling Water Cooled