Naslov
Influence of Modelling Options in RELAP5/SCDAPSIM and MAAP4 Computer Codes on Core Melt Progression and Reactor Pressure Vessel Integrity

Autori
Šadek, Siniša ; Špalj, Srđan ; Glaser, Bruno

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
Proceedings of the TopSafe 2008 Conference / D'Auria, Francesco ; Čavlina, Nikola - Brisel : European Nuclear Society (ENS), 2008, A1-107.1

ISBN
978-92-95064-06-5

Skup
TopSafe 2008 Conference

Mjesto i datum
Dubrovnik, Hrvatska, 30.09.2008. - 03.10.2008

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
MAAP4; SCDAP/RELAP5; vessel integrity

Sažetak
RELAP5/SCDAPSIM and MAAP4 are two widely used severe accident computer codes for the integral analysis of the core and the Reactor Pressure Vessel (RPV) behaviour following the core degradation. Additionally, MAAP4 code has the capability to simulate containment response after release of the primary system inventory. MAAP4 is a fast-running parametric code that produces credible results although it utilizes the simplified form of the conservation equations and the coarser discretization of the reactor systems. RELAP5/SCDAPSIM code is a best-estimate code that contains more mechanistic physics models than the other codes for both severe accident and thermal-hydraulic phenomena. The objective of the paper was to compare code results by applying different modelling options and to evaluate influence of thermal-hydraulic conditions on core damage progression. The intention was not general validation of codes but examination of code results for the same specific transient by using qualified input models. The analysed transient was postulated Station Blackout (SBO) in NPP Krško with a leakage from Reactor Coolant Pumps (RCP) seals. Two groups of runs were performed where each group had a different break area and thus a different leakage rate from the Reactor Coolant System (RCS). Break flow areas differed by a factor of two. The target results were the time when the molten core material slumps to the lower head and the time when the lower head wall fails due to interaction with the molten material. Parameters which affect core melt accident progression and debris bed behaviour in the lower head were discussed and their impact on RELAP5/SCDAPSIM and MAAP4 results were presented. Integrity of the RPV lower head was assessed using a) COUPLE code that is a two-dimensional, finite element heat conduction code incorporated in the RELAP5/SCDAPSIM code, and b) the relevant MAAP4 lower head models.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

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