Best estimate analysis of PHEBUS FPT1 experiment bundle phase using ASTEC code ICARE module

Abstract

The main objective of the PHEBUS FPT1 experiment was to study the release of fission products and their subsequent transport and deposition in the primary circuit and the containment under the conditions representative of a severe accident of a Pressurised Water Reactor. The FPT1 test was divided into the bundle degradation, aerosol, washing and chemistry phases. The objective of this paper is related to the best estimate analysis of the bundle degradation phase using ASTEC code ICARE module. GRS (Germany) best estimate method was used for the simulation of FPT1 test by employing SUSA 3.5 package. The performed best estimate analysis showed that ICARE module is capable to model the main severe accidents phenomena in the fuel bundle, heating and melting, taking into account the used physical and code parameters uncertainties.

Analysis of the Processes in Spent Fuel Pools in Case of Loss of Heat Removal due to Water Leakage

“…Differences in results of hydrogen generation exist due to temperature changes in the top part of SFA: in ASTEC and RELAP/SCDAPSIM calculations rapid increase of temperature in top part and oxidation occurs while in ATHLET-CD calculation oxidation do not start here. As it is shown in paper [10] is the hydrogen generation in ASTEC code during fuel cladding oxidation at temperature range over 2000 ∘ C is overestimated from 10 to 30 percent; therefore, total amount of generated hydrogen could be between 3600 and 4500 kg. Main sequence of events, in the case of water leakage from spent fuel pools in Ignalina NPP, calculated using ATHLET-CD, ASTEC, and RELAP/SCDAPSIM codes, is presented in Table 4.…”

Uncertainty Quantification of the PHEBUS FPT-1 Test Modelling Results

“…This computer code has been developed for the best estimate simulation of LWR coolant systems during normal operation and severe accident conditions [13,17]. RE-LAP/SCDAPSIM code consist of two parts: the RELAP part calculates the overall thermal hydraulic response; the SCDAP part includes user-selectable reactor component models for LWR fuel rods, and includes models to treat the later stages of severe accident In this work, a previously developed model was used [18]. Figure 4 presents a schematic view of axial nodalization of RELAP model for PHEBUS facility.…”

“…Radial nodalization of SCDAP shroud component is presented in Figure 6. More details and model descriptions can be found in references [17,18]. dle.…”

“…In this work, it was decided to evaluate uncertainties that come from the thermal properties of materials (Table 1) and modelling parameters of SCDAP (Table 2). The ranges of the uncertainty analysis, as well as PDF, were chosen according to experience [17,18,24] and engineering judgment. For some SCDAP parameters the uncertainty ranges reach 50% from the initial value, because it was not known how strong an effect these uncertainties will give to the calculation results in severe accident conditions.…”

QUENCH-3 eksperimento modeliavimas ASTEC programų paketu

“…atrinkti įvadiniai aSteC modelio parametrai, jų vertės "pagrindiniame skaičiavime", sumažintos ir padidintos vertės bei keitimo dydis procentais nuo pagrindinės vertės pateikti 1 lentelėje. Parametrų kitimo ribos buvo parinktos vadovaujantis anksčiau sukaupta modeliavimo patirtimi [18] bei straipsnių apie QUenCH eksperimentų modeliavimą analize. kaitinimo elementų varžos (lemiančios rinklės kaitinimo galią) keitimo ribos buvo parinktos peržvelgus kitų autorių straipsniuose pateiktus QUenCH eksperimentų modeliavimo aprašymus.…”