FY 1995 progress report on the ANS thermal-hydraulic test loop operation and results

Comparison of the PLTEMP code flow instability predictions with measurements made with electrically heated channels for the advanced test reactor.

“…is used to predict the onset of flow instability in 42 of these tests. The ability of the code to predict flow instability in these tests reasonably accurately, as well as the ability of the code to predict the onset of flow instability as measured in other electrically heated tests 3,6,7 , as reported by Olson,5 lead to the conclusion that the code should be able to predict the onset of flow instability reasonably well for the University of Missouri Research Reactor (MURR) after it is converted from HEU to LEU fuel.…”

“…What was once called "autocatalytic vapor binding" is actually a form of flow instability that results from a minimum in the demand (or system resistance) curve, as shown in Figure 1, which, in turn, is brought about by sufficient subcooled nucleate boiling. Olson 5 shows that the Whittle and Forgan relationship, as implemented in PLTEMP/ANL and with η = 32.5, predicts flow instability reasonably well for the tests conducted at ORNL and reported by M. Siman-Tov et al 6,7 Olson indicates that these tests were conducted with geometries relevant to research reactor conversion studies with coolant exit pressures of 1.75 to 28.8 bar, and with heat flux from 70 to 1800 W/cm 2 .…”

“…Olson 5 has shown that the PLTEMP/ANL code accurately predicts the powers at which flow instability occurs in the Whittle and Forgan experiments. He also considered the electrically heated tests performed in the ANS Thermal-Hydraulic Test Loop at ORNL and report by M. Siman-Tov et al 6,7 The purpose of this memorandum is to demonstrate that the PLTEMP/ANL code accurately predicts the Croft and the Waters tests. This demonstration should provide sufficient confidence that the PLTEMP/ANL code can adequately predict the onset of flow instability for the converted MURR.…”

Research and Development of Multiphysics Models in Support of the Conversion of the High Flux Isotope Reactor to Low Enriched Uranium Fuel

“…During the design process for the ANSR, many experiments were performed in order to establish a safety basis for the reactor operations and to better quantify the design requirements. Flow tests measuring thermal characteristics of the fuel plates were performed that were designed to measure the heat transfer capabilities of the design [104][105][106][107]. Another set of experiments were performed to test the deflection caused by the pressure differentials from the coolant flow [101,63,102,59,103,108,109,110].…”