Intercode Comparison of SBO Scenario for AHWR

The strong earthquake followed by tsunami, a low-frequency and high-consequence natural disaster, at Fukushima, has shaken the world’s faith in nuclear energy. The new reactor design around the world has started looking ways to mitigate this scenario with innovative design features, whereas every nuclear country has started reviewing their existing reactor response to this scenario minimizing the consequences or limiting the damage progression. India has designed an advanced reactor concept, i.e., advanced heavy-water reactor (AHWR). This reactor has many passive design features to mitigate the consequences not only for the postulated design basis events but also for beyond design basis events. During station blackout (SBO) scenario leading to hot shutdown, the isolation condensers (ICs) are intended to remove decay heat with the help of overhead large pool of water, i.e., gravity-driven water pool (GDWP). This paper outlines the assessment of station blackout scenario for AHWR using the last version of the French best estimate computer code CATHARE2/V2.5_2 and its comparison with RELAP5/Mod3.2 findings. First, it explains the modeling of main heat transport system of AHWR and isolation condenser loop along with GDWP in CATHARE2 followed by thermal-hydraulic safety assessment of station blackout scenario and comparison of predictions with RELAP5 findings.