Coolant Flow Conditions Research Articles

A study of the sensitivity of loca heat transfer analysis for a water-cooled reactor system

Abstract Results are given of computer calculations, using the reactor thermal analysis code THETA1-B, to determine the significance and relative importance of various heat transfer regimes in predicting maximum fuel cladding temperature for the blowdown phase of a postulated loss-of-coolant accident (LOCA) in a pressurized water reactor system. The factors considered include the choice of heat transfer correlation for a particular heat transfer regime, the method of delineating the boundaries between regimes, and core inlet coolant flow conditions. For a hot-leg rupture, the maximum surface temperature is sensitive to a number of factors, including choices of critical heat flux correlation, flow boiling transition heat transfer correlation, and in particular, stable film flow boiling correlation. However, for a LOCA resulting from a double-ended rupture of an inlet feeder, these factors have only marginal effects on maximum cladding temperature. In this case the importance of heat transfer to dry steam coolant at low net flow rate conditions is demonstrated, indicating a need for further information.

Gas Film Cooling—Effects of Coolant Flow Conditions

Technical Briefs Gas Film Cooling—Effects of Coolant Flow Conditions George W. Haering George W. Haering Department of Mechanics, Escola de Engenharia de Sa˜o Carlos, Universidade de Sa˜o Paulo, Sa˜o Carlos, Sa˜o Paulo, Brazil Search for other works by this author on: This Site PubMed Google Scholar Author and Article Information George W. Haering Department of Mechanics, Escola de Engenharia de Sa˜o Carlos, Universidade de Sa˜o Paulo, Sa˜o Carlos, Sa˜o Paulo, Brazil J. Heat Transfer. Aug 1970, 92(3): 553-555 (3 pages) https://doi.org/10.1115/1.3449718 Published Online: August 1, 1970 Article history Received: July 2, 1969 Online: August 11, 2010

Water Cooled Targets for Intense Ion Beams

Target backings cooled by water in linear flow have proven capable of dissipating heat loads from 2 kW ion beams focused to about 20 mm2 for extended periods without structural failure. In addition to the more obvious modes of failure by plastic deformation and melting, metallographic studies of damaged targets have revealed deep void penetrations along grain boundaries. The targetry limitations imposed on maximum usable beam power by heat transfer from the backing to the cooling fluid have been investigated. Neutron producing lifetimes of LiF targets have been compared for different proton beam and coolant flow conditions.

Time Constant of Cylindrical Fuel Pin with Axial Coolant Flow

From the time dependent heat conduction and temperature distribution, an expresston is derived for the time constant in a cylindrical fuel pin and cladding with axial coolant flow. The power production and the inlet temperature are functions of time. In the radial direction perfect mtxing of the coolant is assumed. The average coolant temperature in a region is the average between inlet and outlet temperature assuming a linear rise tn the axial direction. The set of partial differential equations can be solved by means of Laplace transform. The reciprocal of the roots of the characteristic equation for the temperature in the transform domain represents the time constants. The smallest root represents the dominant transient time constant. This doniinant time constant is compared with a qualitative expression ior the thermal relaxation time of a reactor after a power change given by Bethe. The numerical example used is a fuel pin in EBR-I Mark III in flowing NaK coolant at a core power generation of 1 Mw at various coolant flow conditions. (auth)