LABORATORI NAZIONALI DI LEGNARO
In the first week while the Fukushima event was still ongoing, we used our PC-based simulation software PCTRAN to do a “forensic” type analysis. Since lack of control room data recording, the sequence of events was based on the sketchy transcript released by the Japanese authorities. The transient results turned out to be highly agreeable with later findings at all four units. We will make a brief demonstration of this simulation. The code was first developed at the aftermath of TMI event over 30 years ago. The author participated in the upgrade of the undamaged Unit 1 project. Better understanding of the thermal-hydraulics of small break LOCA has resulted in improvement in plant equipment and operations. Other PCTRAN models were later developed for various operating plants and new Generation 3 designs. Fukushima was tragic because the scale of earthquake and tsunami was way beyond its design limit. Newer designs have better seismic resistance and more importantly – further redundancy and passive devices to handle the decay heat. We shall also present our Westinghouse AP1000 and Areva EPR models upon a station blackout event. The consequence should be stabled cool-down without core damage or dose release. The three major nuclear disasters – TMI, Chernobyl and Fukushima – each have taught the world a lesson. Respectively they are lack understanding in two-phase flow (TMI), reactivity feedback (Chernobyl) and backup power and water supply (Fukushima). None of these are technically insurmountable. For countries temporarily suspend nuclear construction we would suggest them keep the nuclear option open – at least by maintaining a reasonable sized R&D community. Otherwise the know-how will be lost or dispersed for good.

DATA: 11-10-2011

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