The document deals with the post-test analysis of an experiment performed in LOBI 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 experiment was selected by OECD/NEA/CSNI (Organization for Economic Cooperation and Development / Nuclear Energy Agency / Committee on the Safety of Nuclear Installations) as International Standard Problem (ISP) 18. ISP 18 was a Small Break Loss of Coolant Accident (SBLOCA) scenario without the actuation of the High Pressure Injection System (HPIS). The peculiarity of the experiment was the level in the system that established at an elevation close to the connection of the cold leg with the reactor pressure vessel: this caused the possibility of both liquid and steam to exit the break: the difference of the two situations was noticeable and caused wrong prediction by many computer codes. UNIPI blind calculation demonstrated to be the best among about thirty submitted set of results by all top level research institutes involved with nuclear thermal-hydraulics and accident analysis. The work was discussed in a specific EURATOM/OECD Workshop in Varese where University of Pisa represented Italy.
Post-test analysis performed at DCMN of Pisa University by RELAP4/MOD6 and RELAP5/MOD1 codes of the LOBI A2-81 test (ISP 18)
D'Auria F.
Secondo
Supervision
;
1985-01-01
Abstract
The document deals with the post-test analysis of an experiment performed in LOBI 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 experiment was selected by OECD/NEA/CSNI (Organization for Economic Cooperation and Development / Nuclear Energy Agency / Committee on the Safety of Nuclear Installations) as International Standard Problem (ISP) 18. ISP 18 was a Small Break Loss of Coolant Accident (SBLOCA) scenario without the actuation of the High Pressure Injection System (HPIS). The peculiarity of the experiment was the level in the system that established at an elevation close to the connection of the cold leg with the reactor pressure vessel: this caused the possibility of both liquid and steam to exit the break: the difference of the two situations was noticeable and caused wrong prediction by many computer codes. UNIPI blind calculation demonstrated to be the best among about thirty submitted set of results by all top level research institutes involved with nuclear thermal-hydraulics and accident analysis. The work was discussed in a specific EURATOM/OECD Workshop in Varese where University of Pisa represented Italy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
