Category Archives: Natural circulation data and methods for advanced water cooled nuclear power plant designs

NATURAL CIRCULATION SYSTEMS IN NEW DESIGNS

1.1. THE ROLE OF NATURAL CIRCULATION SYSTEMS The role of the natural circulation systems should be considered in the general context of implementation of passive safety systems into new nuclear power plant designs. It may be noted that many systems and equipment proposed in future reactor concepts include natural circulation phenomena as the main mechanism that determines the passivity of […]

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CAPCN test facility

A high-pressure natural convection loop (CAPCN) was constructed and operated to produce data in order to verify the thermal hydraulic tools used to design the CAREM integral LWR design, mainly the dynamical response. This is accomplished by the validation of the calculation procedures and codes for the rig working in states that are very close to the operating states of […]

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SUMMARY

It was demonstrated that the change from stratified conditions to natural circulation (and vice versa) is essential for many passive safety systems of the SWR 1000. It would be useful if these flow phenomena could be studied by means of computer code analyses. But in many cases, suitable computer codes are not yet available and development of such codes to […]

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Theoretical analysis and research for AC600/1000 passive containment cooling behavior

PCCAC-2D is a two dimension computer code which has be already used in the design of AC600/1000 passive containment cooling system. PCCAC-3D is a three dimension computer code which will be finished by the end of next September. PCCAC-2D, 3D can be used to predict the pressure and temperature of mixing gas inside the containment following the accident of primary […]

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APROS calculation with the new thermal stratification solution model

Due to obvious deficiencies in the calculations with previous APROS versions a new solution model for the thermal stratification of APROS code was developed [23]. The old method used upwind solution for the enthalpy. Due to numeric diffusion the code lost information about the stratified layer. The new higher order numeric method uses information from three consecutive nodes to solve […]

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Two-phase thermal-hydraulics and heat transfer

In general, thermal hydraulic modelling of nuclear reactor systems is based on the one­dimensional approach. Thermal hydraulic modelling of the steady state, transient and stability behaviour of two-phase natural circulation systems is no exception to this general approach. System codes have reached a highly developed modelling status and a wide acceptance. They can reproduce accurately enough most of the existing […]

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GENERAL THEORY OF NATURAL CIRCULATION FLOW RATE

In designing heat removal systems, we often rely on both single and two-phase natural circulation. The fluid heats and expands, and may boil and the two-phase flow generates an increased pressure drop. The inlet flow is derived from a pump, or a downcomer with a hydrostatic head, so that when there are many channels in parallel, as in a reactor, […]

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Siphon Condensation NC (SCNC)

The decreasing of NC driving forces, the small temperature difference across U-Tubes of steam generators, and the occurrence of the CounterCurrent Flow Limiting Phenomenon (CCFL) at the entrance of U-tubes are at the origin of wide system oscillations of core inlet flowrate, e. g. Ref. [10]. The phenomenon has been investigated in Refs. [5] and [11], based on a natural […]

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Influences of buoyancy and thermal boundary conditions on heat transfer with naturally-induced flow

J. D. Jackson, J. Li University of Manchester, United Kingdom Abstract. A fundamental study is reported of heat transfer from a vertical heated tube to air which is induced naturally upwards through it by the action of buoyancy. Measurements of local heat transfer coefficient were made using a specially designed computer-controlled power supply and measurement system for conditions of uniform […]

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The NOKO facility imbedded in the matrix of two-phase-flow facilities in western Europe

In Fig. 1, some European test facilities capable to perform thermal-hydraulic tests with passive safety systems are shown. It is evident that the wide spread of power and pressures will allow the testing of the same component in several facilities of different size and thus increasing the confidence in the assessment of the effectiveness of this component. It has to […]

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