SPES/SP-FW-02, Total Loss Feedwater with Emergency Feed Water Delayed in SPES facility

1 - Description of test facility: The SPES (Simulatore PWR per Esperienze di Sicurezza) integral test facility is a three loop scaled-down model of PWR (Westinghouse 3122 type, 3 loops, 2775 MWth core power) designed for thermal-hydraulic safety research program. SPES test program provides experimental data for the development and assessment of system codes used in PWR safety analysis. SPES is an experimental facility which allows a true simulation of a PWR system as close as possible to the characteristic of the Westinghouse 312 type. The test plant reproduces the primary loops, the most important components and the power channel of the simulated reactor according to significant scaling criteria. The SPES experimental facility, having a 1:427 power-scaling ratio includes a full-length-scale electrical heated power channel and three complete primary loops. In particular SPES system simulates: a) the whole primary circuit; b) the secondary system restricted to: - steam generator secondary side; - main feedwater lines downstream the isolation valves; - main steam lines upstream the turbine stop valve. c) the most significant auxiliary and emergency systems: - charging and letdown systems; - safety injection systems (HPIS, LPIS, accumulators, EFWS); - steam dump. 2 - Description of test: The ISP22 test is a Loss of Main Feed Water in all the three steam generators. The purpose of 'LOFW-EFW delayed' experiment is to obtain in the primary system of the facility the thermal-hydraulic conditions similar to the reference plant in the incidental transient of main feedwater total loss, in all the three steam generators, with a delayed intervention of the emergency feedwater system. The most important phenomenologies related to the experiment are the following: - steam generator heat removal capability in conditions of degraded secondary inventory (due to the main feedwater total loss EFW intervention delayed) and degraded primary inventory (due to mass loss through the pressurizer PORV); - power channel heat transmissions when the rods are partially uncovered (as a consequence of the primary mass reduction) with or without two phase natural circulation; - conditions of single phase (steam, liquid) or two phase flow through the pressurizer PORV; - evaluation of core coolability with EFW delayed intervention; - EFW intervention effects with void redistribution in the primary circuit and natural circulation establishment (related to residual primary inventory)