Measurements of Fundamental Fluid Physics of SNF Storage Canisters

Abstract

SummaryWith the University of Idaho, Ohio State University and Clarksean Associates, this research program has the long-term goal to develop reliable predictive techniques for the energy, mass and momentum transfer plus chemical reactions in drying / passivation (surface oxidation) operations in the transfer and storage of spent nuclear fuel (SNF) from wet to dry storage. Such techniques are needed to assist in design of future transfer and storage systems, prediction of the performance of existing and proposed systems and safety (re)evaluation of systems as necessary at later dates.Many fuel element geometries and configurations are accommodated in the storage of spent nuclear fuel. Consequently, there is no one generic fuel element / assembly, storage basket or canister and, therefore, no single generic fuel storage configuration. One can, however, identify generic flow phenomena or processes which may be present during drying or passivation in SNF canisters. The objective of the INEEL tasks was to obtain fundamental measurements of these flow processes in appropriate parameter ranges.With the University of Idaho, an idealization of a combined drying and passivation approach has been defined in order to investigate the generic flow processes. This simulation includes flow phenomena that occur in canisters for high-enrichment and medium-enrichment fuels, where fuel element spacing in the canister is increased as compared with low enrichment fuel. Canister diameter was taken as 46 cm (18 in.) and a single basket of about 1.3 meters (4 ft.) length was considered. A long central tube ("dip tube") served as the inlet as in one earlier concept for a passivation process; while this concept apparently has not yet been selected for application, it provides an excellent example of the coupled, complex phenomena which may be present in canister flows. Suggested design flow rates for this hypothesized application indicate that the Reynolds number in the inlet tube would be expected to be between 2500 and 5000, i.e., relatively low.The local distributions of convective mass transfer characteristics (drying/passivation) are expected to depend on the freestream turbulence in the flow around stored fuel elements. The magnitudes of this turbulence depend on the turbulence distributions on the upstream side of the perforated basket support plate ("inlet plenum") and, in turn, in the impinging jet and in the inlet tube. This information can assist engineers in understanding variations of surface drying and passivation through an array and approaches to modify designs to counter non-uniformities and to improve iii distribution, as well as providing bases for assessment of computational fluid dynamics codes proposed for the purpose.A water-flow experiment with a 3/4-scale model (relative to the idealized canister) has been used for overall flow visualization and velocity measurements, with and without an array of simulated fuel elements. Observations have been made with perforated plates (representing basket support plates) having...

Development Of An Experiment For Measuring Flow Phenomena Occurring In A Lower Plenum For VHTR CFD Assessment

“…Consequently, classical wisdom and textbook descriptions for jet characteristics are not necessarily valid for the near-field mixing of jets in industrial applications such as a VHTR flow geometry (Figure 9). Few studies of impinging jets have utilized fullydeveloped turbulent flows for the jet inlet [Cooper et al, 1993;Condie, McCreery and McEligot, 2001]. Figures 5 and 9 show that the flow transitions from cooling channels to lower plenums in typical gas-cooled reactors involve short ducts.…”

“…For gas turbine cooling [Simon et al, 1999], the jet is formed by passage through a short orifice passage so the initial velocity profile of the jet is near uniform; this uniform profile is typical of many experiments where the jet is formed from a converging nozzle and of many numerical predictions. Condie, McCreery and McEligot [2001] summarized the fluid physics references found for simple axisymmetric impinging jets in general. With the exception of the outflow study of Moller [1963], the jets from fully-developed flows were measured in semi-infinite surroundings [Cooper et al, 1993;Kim, Wiedner and Camci, 1995;Lee and Lee, 2000].…”

Initial Scaling Studies and Conceptual Thermal Fluids Experiments for the Prismatic NGNP Point Design

“…Consequently, classical wisdom and textbook descriptions for jet characteristics are not necessarily valid for the near-field mixing of jets in industrial applications such as an NGNP flow geometry (Figure 11). Few studies of impinging jets have utilized fully-developed turbulent flows for the jet inlet [Cooper et al, 1993;Condie, McCreery and McEligot, 2001]. Figures 6 and 11 show that the flow transitions from cooling channels to lower plenums in typical gas-cooled reactors involve short ducts.…”

“…For gas turbine cooling [Simon et al, 1999], the jet is formed by passage through a short orifice passage so the initial velocity profile of the jet is near uniform; this uniform profile is typical of many experiments where the jet is formed from a converging nozzle and of many numerical predictions. Condie, McCreery and McEligot [2001] summarized the fluid physics references found for simple axisymmetric impinging jets in general. With the exception of the outflow study of Moller [1963], the jets from fully-developed flows were measured in semi-infinite surroundings [Cooper et al, 1993;Kim, Wiedner and Camci, 1995;Lee and Lee, 2000].…”

Flow Visualization of Forced and Natural Convection in Internal Cavities

“…As noted, proposed operating conditions give typically low Reynolds number flows. For an extensive literature survey of related work, see Condie, et al [2001].…”