The present paper deals with the post test analysis of PKL III E2.2 and E3.1 experiments, by RELAP5/Mod3.3 code. These experiments have been executed in the framework of the OECD/SETH Project in the integral test facility PKL III which is operated by AREVA NP GmbH in Erlangen, Germany. The main purpose of the project is to investigate pressurized water reactor safety issues related to boron dilution phenomena. In particular, the E2.2 experiment investigates the boron dilution issue during a small break LOCA transient and the E3.1 experiment investigates the boron dilution issue during shut down conditions (for refueling) with the reactor coolant system closed and the reactor placed in mid loop operation conditions. This analysis is focused on assessing the capability of the RELAP5 code to correctly predict boron dilution phenomena and the thermalhydraulic parameters in transients with a) asymmetric loop behavior, b) natural circulation in one and two-phase flow, c) steam generator in reflux condenser mode, and (only for E3.1 experiment) d) the primary system under low pressure conditions in the presence of nitrogen. The E2.2 calculated results show a good agreement with regard to the main thermal-hydraulic experimental parameters but show that is challenging for the code predict the different natural circulation onset in the loops. A sensitivity analysis, carried out by simulating the SG primary side with seven U-tubes of seven different lengths, show that the code predicts the delay of the onset of the natural circulation in the loop 2. The E3.1 experiment demonstrates that it is challenging for the code because it is at low pressure and in the presence of non-condensable (nitrogen). Sensitivity analyses have focused on these transients. The results of these sensitivity analyses show the importance of the mass flow through the upper head by-pass to predict the main thermal-hydraulic parameters during the transients.
Analysis by Relap5 code of boron dilution phenomenon in Small Break LOCA and in Mid-Loop Transients performed in PKL-III Test Facility
D'AURIA, FRANCESCO SAVERIO
2008-01-01
Abstract
The present paper deals with the post test analysis of PKL III E2.2 and E3.1 experiments, by RELAP5/Mod3.3 code. These experiments have been executed in the framework of the OECD/SETH Project in the integral test facility PKL III which is operated by AREVA NP GmbH in Erlangen, Germany. The main purpose of the project is to investigate pressurized water reactor safety issues related to boron dilution phenomena. In particular, the E2.2 experiment investigates the boron dilution issue during a small break LOCA transient and the E3.1 experiment investigates the boron dilution issue during shut down conditions (for refueling) with the reactor coolant system closed and the reactor placed in mid loop operation conditions. This analysis is focused on assessing the capability of the RELAP5 code to correctly predict boron dilution phenomena and the thermalhydraulic parameters in transients with a) asymmetric loop behavior, b) natural circulation in one and two-phase flow, c) steam generator in reflux condenser mode, and (only for E3.1 experiment) d) the primary system under low pressure conditions in the presence of nitrogen. The E2.2 calculated results show a good agreement with regard to the main thermal-hydraulic experimental parameters but show that is challenging for the code predict the different natural circulation onset in the loops. A sensitivity analysis, carried out by simulating the SG primary side with seven U-tubes of seven different lengths, show that the code predicts the delay of the onset of the natural circulation in the loop 2. The E3.1 experiment demonstrates that it is challenging for the code because it is at low pressure and in the presence of non-condensable (nitrogen). Sensitivity analyses have focused on these transients. The results of these sensitivity analyses show the importance of the mass flow through the upper head by-pass to predict the main thermal-hydraulic parameters during the transients.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
