Yi-Hsiang Cheng

Benchmark Calculations of Pressurizer Model for Maanshan Nuclear Power Plant Using TRACE Code

Pressurizer plays an important role in controlling the pressure of the primary coolant system in pressurized water reactor (PWR) power plants. An accurate modelling of the pressurizer is needed to determine the pressure histories of the primary coolant system, and thus to successfully simulate overall PWR power plant behavior during transients. The purpose of this study is to develop a pressurizer model, and to assess its pressure transients using the TRACE code version 5.0. The benchmark of the pressurizer model was performed by comparing the simulation results with those from the tests at the Maanshan nuclear power plant. Four start-up tests of the Maanshan nuclear power plant are collected and simulated: 1) turbine trip test from 100% power; 2) large-load reduction at 100% power; 3) net-load trip at 100% power; and 4) net-load trip at 50% power. The simulation results are in reasonable agreement with the start-up tests, and thus the pressurizer model built in this study is successfully verified and validated.Copyright

A STUDY OF STEAM-WATER COUNTERCURRENT FLOW MODEL IN TRACE CODE

This paper studied the countercurrent flow model in the TRACE code version 5.0. Steam and water are chosen as the working fluids that flow counter-currently in a circular pipe. Three types of the countercurrent flow models, the Wallis, the Kutateladze and the Bankoff correlations, are investigated. A single pipe model was built for the studies of the Wallis and the Kutateladze correlations, and the variable in the calculation model is the pipe diameter. A perforated plate model was built to study the Bankoff correlation, and the variables include the pipe diameter, the hole diameter, the number of holes and the plate thickness. The hydraulic diameter of the pipe varies from 2.5–200 mm for validating both the Wallis and the Kutateladze correlations. While validating the Bankoff correlation, the hydraulic diameter of the pipe is of 50 and 200 mm, and the plate thickness changes as 10 and 40 mm. Through this study, we validate the countercurrent flow model in the TRACE code, and provides comments on the application ranges of these three correlations.Copyright

Maanshan PWR Loss of Flow Transients Analysis With TRACE

TRACE model of Maanshan Nuclear Power Plant (three-loop PWR) was used to analyze Loss of Flow transient as defined in FSAR Chapter 15. The results were compared with those from RETRAN02 and LOFTRAN/THINC licensing analysis of Westinghouse Inc. Three different initiation events were involved in this analysis: Partial Loss of Flow (PLOF), Complete Loss of Flow-Under Voltage (CLOF-UV) and Complete Loss of Flow-Under Frequency (CLOF-UF). This paper compared important thermal hydraulic parameters at steady state, such as the pressure of pressurizer, cold-leg temperature, and the pressure of steam generator, etc.. It also compared system parameters under transient conditions, such as core thermal power, core flow rate, and pressure of pressurizer, etc.. It is concluded that the steady state results of TRACE calculations are in general good agreements with those from RETRAN02 and have a largest error of 3.03% in the steam generator flow. For transient condition, TRACE results are also comparable with those from LOFTRAN and RETRAN02. In summary, our studies show that Maanshan TRACE model is correct and accurate enough for future safety analysis applications.Copyright

An Intelligent Code to Design Thermoelectric Heat Pumps

Thermoelectric heat pumps (TEHPs) have been applied to many electronic devices to create a steady, low-temperature operating environment. The cooling capacity is the critical issue in the application consideration. This study uses a hybrid genetic algorithm (hGA) to maximize the cooling capacity of a two-stage TEHP under the condition that the amount of material being used is limited. For a two-stage TEHP with separate electrical currents, the design parameters of each stage: the applied electrical current, the number of thermoelectric elements, and the ratio of area to length of the thermoelectric elements, are optimized. The optimal parameter set of a two-stage TEHP is determined for various cold-side temperatures, and the cooling capacity is thus maximized. This study demonstrates that the hGA has the ability to design a complex TEHP, and converge to the optimal parameter set much quickly.

Application of genetic algorithm to maximizing the cooling capacity in a thermoelectric cooling system

Thermoelectric cooling (TEC) system has grown significantly because of the need for a steady, low-temperature operating environment for numerous electronic devices. The cooling capacity of the TEC system should be maximized in considering applications. The TEC system usually consists of a TEC device and an external hot-side heat exchanger. While the heat transfer effect of the hot-side heat exchanger is limit, the optimization of the dimensions of thermoelectric elements could increase the cooling capacity. This study proposed a novel approach of optimizing the dimensions of thermoelectric elements via genetic algorithm (GA), to maximize the cooling capacity. Parameters, including the element length, the element area and the number of elements, were taken as the variables. The results show that GA can determine the optimal dimensions while the heat transfer effect of the hot-side heat exchanger is considered