Steam separator modeling for various nuclear reactor transients
In a pressurized water reactor steam generator, a moisture separator is used to separate steam and liquid and to insure that essentially dry steam is supplied to the turbine. During a steam line break or combined steam line break plus tube rupture, a number of phenomena can occur in the separator which have no counterparts during steady-state operation. How the separator will perform under these circumstances is important for two reasons, it affects the carry-over of radioactive iodine and the water inventory in the secondary side. This study has as its goal the development of a simple separator model which can be applied to a variety of steam generator for off-design conditions. Experiments were performed using air and water on three different types of centrifugal separators: a cyclone as a generic separator, a Combustion Engineering type stationary swirl vane separator, and a Westinghouse type separator. The cyclone separator system has three stages of separation: first the cyclone, then a gravity separator, and finally a chevron plate separator. The other systems have only a centrifugal separator to isolate the effect of the primary separator. Experiments were also done in MIT blowdown rig, with and without a separator, using steam and water. The separators appear to perform well at flow rates well above the design values as long as the downcomer water level is not high. High downcomer water level rather than high flow rates appear to be the primary cause of degraded performance. Appreciable carry-over from the separator section of a steam generator occurs when the drain lines from three stages of separation are unable to carry off the liquid flow. Failure scenarios of the separator for extreme range of conditions from the quasi-steady state transient to the fast transients are presented. A general model structure and simple separator models are provided.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Nuclear Regulatory Commission, Washington, DC (USA). Div. of Reactor and Plant Systems; Electric Power Research Inst. (EPRI), Palo Alto, CA (United States)
- OSTI ID:
- 6193992
- Report Number(s):
- NUREG/CR-4922; EPRI-NP-5272; ON: TI87900828
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PWR TYPE REACTORS
STEAM SEPARATORS
FAILURES
MATHEMATICAL MODELS
EXPERIMENTAL DATA
FLUID FLOW
REACTOR ACCIDENTS
TRANSIENTS
ACCIDENTS
DATA
INFORMATION
NUMERICAL DATA
REACTORS
SEPARATION EQUIPMENT
VAPOR SEPARATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled