The document deals with the post-test analysis of an experiment performed to characterize the LOBI system performance in the configuration Mode2. LOBI was a Pressurized Water Reactor (PWR) simulator installed in the EC center of Ispra Italy financially supported by EURATOM. The configuration Mod2 of LOBI was designed as a consequence of the Three Mile accident in US and is the follow-up of the configuration Mod1. Mod2 was designed to simulate stratification phenomena and natural circulation which are important during Small Break Loss of Coolant Accidents (SBLOCA); as a difference Mod1 was designed to simulate phenomena expected during Large Break Loss of Coolant (LBLOCA) scenarios. Namely downcomer size in Mod2 was much smaller than in the case of Mod1 and a large number of Emergency Core Cooling Systems (ECCS) were installed in Mod2. The concerned SD-SL-03 experiment was performed to characterize the facility. The code application allowed the optimization of the nodalization by Relap 4 preparing for the campaign of experiments. Furthermore the comparison between experiment and calculation constituted the basis for developing accuracy quantification method. (relevant to code validation) . The relevance of this document lies in the demonstration of huge effect upon the calculated transient of the modeling (nodalization choices made by code user) of the Upper downcomer region of the LOBI facility in relation to which experimental data are available: similar influence is expected in modeling of the Nuclear Power Plant. The document was at the basis of the decision (not only from the side of the University of Pisa) to move from Relap4 to Relap5 where lower nodalization dependent results were expected. The work was discussed in a specific meeting of the so-called SBATF research group where University of Pisa represented Italy.

Analysis of the influence of the upper downcomer nodalization on the LOBI test SD-SL-03 using RELAP4/MOD6

D'Auria F.
Primo
Investigation
;
1983

Abstract

The document deals with the post-test analysis of an experiment performed to characterize the LOBI system performance in the configuration Mode2. LOBI was a Pressurized Water Reactor (PWR) simulator installed in the EC center of Ispra Italy financially supported by EURATOM. The configuration Mod2 of LOBI was designed as a consequence of the Three Mile accident in US and is the follow-up of the configuration Mod1. Mod2 was designed to simulate stratification phenomena and natural circulation which are important during Small Break Loss of Coolant Accidents (SBLOCA); as a difference Mod1 was designed to simulate phenomena expected during Large Break Loss of Coolant (LBLOCA) scenarios. Namely downcomer size in Mod2 was much smaller than in the case of Mod1 and a large number of Emergency Core Cooling Systems (ECCS) were installed in Mod2. The concerned SD-SL-03 experiment was performed to characterize the facility. The code application allowed the optimization of the nodalization by Relap 4 preparing for the campaign of experiments. Furthermore the comparison between experiment and calculation constituted the basis for developing accuracy quantification method. (relevant to code validation) . The relevance of this document lies in the demonstration of huge effect upon the calculated transient of the modeling (nodalization choices made by code user) of the Upper downcomer region of the LOBI facility in relation to which experimental data are available: similar influence is expected in modeling of the Nuclear Power Plant. The document was at the basis of the decision (not only from the side of the University of Pisa) to move from Relap4 to Relap5 where lower nodalization dependent results were expected. The work was discussed in a specific meeting of the so-called SBATF research group where University of Pisa represented Italy.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/891870
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