Showing papers in "Nuclear Engineering and Design in 1990"

TL;DR: In this paper, a 2-fluid thermal-hydraulic code capable of simulating thermal and mechanical phenomena occurring in the primary and secondary circuits of PWRs for a wide variety of accidental situations is presented.

TL;DR: The Code Scaling, Applicability, and Uncertainty (CSAU) as mentioned in this paper evaluation methodology combines a top-down approach to define the dominant phenomena with a bottom-up approach to quantify uncertainty.

TL;DR: In this article, a criterion for determining whether the Operating Basis Earthquake (OBE) has been exceeded after the occurrence of a seismic event at a nuclear power plant is proposed.

TL;DR: In this paper, a comprehensive survey of design basis accidents and the corresponding accident doses in the environment is presented, and it is shown that these doses are much lower than the maximum allowable values given in the German Radiation Protection Ordinance even if it is assumed that the installed filters of the reactor building are not available.

TL;DR: In this paper, new droplet deposition and entrainment models were developed for the purpose of applying the dryout prediction accuracy using ''the film dryout criterion'' for the adiabatic annular mist flow.

TL;DR: The French thermal-hydraulic code CATHARE is being developed in Grenoble by EDF, FRAMATOME and CEA as discussed by the authors and the validation process is performed in two steps: qualification of the models against separate effect tests and verification of the code on integral loop tests.

TL;DR: In this paper, a particular phenomenon of turbulence reduction in bubbly two-phase flow is discussed based on the experimental observations and theoretical derivation of turbulence energy balance equations, and the importance of the mechanisms involved in this phenomenon has been stressed for a better understanding of the complex nature of bubbly 2-phase flows.

TL;DR: The effect of ship motion, such as heaving and rolling, on the thermal-hydraulic behavior of marine reactors was investigated in this paper, where the COBRA-IV-I code was modified to analyse the thermal hydraulic performance on the critical heat flux under oscillating acceleration conditions.

TL;DR: In this article, the authors investigated the ability of multidimensional two-fluid models to predict the observed phase separation and lateral phase distribution phenomena in two-phase flows and showed that such phenomena can be predicted once all significant physical mechanisms have been adequately modelled.

TL;DR: In this article, it was shown that all radiologically relevant fission products are completely retained inside the silicon carbide layer of intact fuel particles and permanent damage to the fission product retaining SiC layer can only start in accidents involving temperatures significantly beyond 1600°C.

TL;DR: In this paper, a set of condensation models for forced and natural convection in the presence of a non-condensable gas was proposed, and the effects of a wavy interface are implemented in this model by using correlations for a rough wall surface.

TL;DR: In this article, the authors compared results from TRAC-PFl/MOD1 code calculations with measurements from separate effects tests and published experimental data for modeling parameters to determine the uncertainty ranges of code input and modeling parameters which dominate the uncertainty in predicting the peak clad temperature for a postulated Large Break Loss of Coolant Accident (LBLOCA) in a four-loop Westinghouse Pressurized Water Reactor.

TL;DR: In this article, a series of single-phase natural circulation tests in a model reactor with rolling motion was performed, in order to investigate the natural circulation characteristics of a marine reactor in a stormy weather.

TL;DR: In this paper, the relationship between bubble diameter and interfacial area was theoretically considered and a preliminary experiment for one of these methods was carried out, with particular attention to bubble diameter at inlet.

TL;DR: The most important experiments at the AVR experiment and their results are discussed in this paper, which illustrates the significance of the experiment for high-temperature reactor development in Germany and for the construction and operation of future HTR projects.

TL;DR: In this article, the validity and limitations of seismic probabilistic risk assessment methods are examined by determining how uncertainties due to inherent variability, modeling assumptions, and incomplete data effect risk estimates and inferences.

TL;DR: In this paper, the authors proposed a methodology to quantify uncertainty called Code Scaling, Applicability and Uncertainty (CSAU), which consists of three primary elements containing 14 steps.

TL;DR: In this article, the main variables affecting environmentally induced crack initiation and growth in low alloy pressure vessel steels exposed to high temperature aqueous environments are reviewed and the main gaps in these data and their interpretation are judged to remain particularly in the case where oxygenated water is present.

TL;DR: In this paper, the authors simulate the outlet plenum in a loop-type LMFBR with an inner barrel and a closed-type UIS (upper instrumentation structure) to study the in-vessel thermal stratification.

TL;DR: A simplified virtual mass force term has been implemented into TRAC-PFI as discussed by the authors, which stabilizes basic equations and numerical calculations, and a large amount of CPU time could be saved in the system calculation.

TL;DR: In this article, the drift flux model was used to predict the thermal-hydraulic transient behavior for a PWR power plant during a small break loss-of-coolant accident (LOCA).

TL;DR: In this paper, the authors developed the Film Dryout Analysis Code in Subchannels (FIDAS) to predict dryout and post-dryout heat transfer in a channel and in rod bundles.

TL;DR: Two modes of single beam ultrasonic techniques, the pulse-echo and the transmission mode, are developed to measure instantaneous liquid levels, time averaged void fraction and interfacial area in a gas-liquid two phase flow system as mentioned in this paper.

TL;DR: The THTR 300 nuclear power plant was successfully commissioned after starting electricity generation in November 1985 as mentioned in this paper, and the operating experience reveals absolutely positive results: the principal design data have been achieved; the Principal design of the large pebble bed reactor was confirmed; and shut down of the plant after the generation of 2.9 million MWh and 423 full power days is due to financial risk of the prototype plant.

TL;DR: In this article, the double peaks of void fraction radial profiles were analyzed by the bubble deposition model and it was found that bubbles segregation according to their size is an important phenomenon which contributes to bubble non-homogeneous distribution in vertical upward two-phase shear flow.

TL;DR: In this article, phase separation for a two-phase mixture flowing through dividing tee junctions with a small ratio of branch to main pipe diameter is analyzed for the case of a stratified flow in a horizontal main pipe connected to a horizontal, vertical upward or vertical downward branch.

TL;DR: In this paper, the authors developed a calculation code for wall thinning due to erosion corrosion in power plant piping systems, which can be applied to reduce non-destructive testing and curtail monitoring programs for piping systems.

TL;DR: In this article, the authors present the CSAU procedure and rational for evaluating the capability of a best estimate code to scale-up processes from reduced scale test facilities to full scale nuclear power plants, and quantifying the effects of scale distortions and/or a limited data base, on code uncertainty to calculate a safety parameter of interest.

TL;DR: In this article, the authors present an interpretative description of loop seal clearing and refilling phenomena obtained at the ROSA-IV Large Scale Test Facility (LSTF) in a Westinghouse-type PWR.

TL;DR: In this paper, a series of sensitivity analyses for multi-story base-isolated structures subject to a harmonic ground excitation is carried out, and the effects of variations in properties of structures and base-isolation systems on the peak responses are studied.