SPES3 Facility RELAP5 Sensitivity Analyses on the Containment System for Design Review

Abstract

An Italian MSE R&D programme on Nuclear Fission is funding, through ENEA, the design and testing of SPES3 facility at SIET, for IRIS reactor simulation. IRIS is a modular, medium size, advanced, integral PWR, developed by an international consortium of utilities, industries, research centres and universities. SPES3 simulates the primary, secondary and containment systems of IRIS, with 1:100 volume scale, full elevation and prototypical thermal-hydraulic conditions. The RELAP5 code was extensively used in support to the design of the facility to identify criticalities and weak points in the reactor simulation. FER, at Zagreb University, performed the IRIS reactor analyses with the RELAP5 and GOTHIC coupled codes. The comparison between IRIS and SPES3 simulation results led to a simulation-design feedback process with step-by-step modifications of the facility design, up to the final configuration. For this, a series of sensitivity cases was run to investigate specific aspects affecting the trend of the main parameters of the plant, as the containment pressure and EHRS removed power, to limit fuel clad temperature excursions during accidental transients. This paper summarizes the sensitivity analyses on the containment system that allowed to review the SPES3 facility design and confirm its capability to appropriately simulate the IRIS plant.

Application of Fractional Scaling Analysis for Development and Design of Integral Effects Test Facility

“…[8] and later on in Ref. [10]. The SPES3 decomposition (see Table 2) is performed so that it serves the purpose not only initially but also during the transient, so that all reconfigurations of the SPES3 System and closing/opening connections between its components may be taken into account.…”

“…To capture this properly, the presented space decomposition (in stage 1) needs to be refined further for the applied GOTHIC/RELAP models by applying an adequate nodalization, as presented in Refs. [4,5], and [10].…”

“…To quantify terms in Eq. (10) and Table 4, additional calculations based on extracted data are needed for each time-step so that right volumes of subvolumes with different fluid properties and compressibility might be quantified.…”

“…The RELAP analysis performed for SPES3 [9,10] was used to support design and later on to provide input data for scaling analysis (step 6 in element 2 of EMDAP) to evaluate the similarities, or differences, between prototype and model responses to various accidents transients scenarios.…”

“…An insight of performed design modifications is available in Ref. [10]. In some cases, the GOTIHC/ RELAP models were improved as well by modifying or replacing heat transfer correlations for some heat exchangers, or by performing renodalization so that modeling of interactions between some components might be improved.…”