Director General of the International Atomic Energy Agency (IAEA) Rafael Mariano Grossi denounced the “violation” of one of the fundamental pillars of nuclear security, but affirmed that at this stage the reduction had no “great consequences”.
There are currently 20,000 spent fuel assemblies stored in the site storage pool. After being used in a reactor, the spent fuel is still radioactive and gives off heat: it is then stored in a “pool” – a pool filled with water – to cool. After its radioactivity and heat output have been reduced sufficiently, after a few years it can be transported and generally transferred to dry storage sites.
Electricity is needed to pump and treat pool water, which may contain small amounts of radioactive isotopes, and to reintroduce cold water. Without electricity, the water would heat up and could theoretically begin to evaporate, just like some of the radioactive isotopes present in water.
However, at Chernobyl, the spent fuel that was moved to dry storage had to be cooled for decades. Since the accident at the Chernobyl nuclear power plant in 1986, “the thermal load of the pool and the volume of cooling water are sufficient to ensure efficient heat removal without electricity,” the IAEA assured. The assessment of the UN nuclear “gendarme” is “understandable, given the age of the nuclear fuel”, and this “significantly reduces the risk of contamination inside the building”, reacted to Twitter Claire Corkhill, professor at the University of Sheffield (UK), specialist in the degradation of nuclear materials.
In a note on the situation in Ukraine, published on February 25, the Institute for Radiation Protection and Nuclear Safety (IRSA) also explains that post-Fukushima accident studies in Japan on the consequences of a complete loss of the cooling pool show a slow increase in the temperature of the water in the pool (up to temperatures around 60°C), but do not open the assemblies, i.e. combustible substances always remain under water.
If, therefore, the risk of radioactive leakage in the current state seems limited, then the situation with nuclear power plants is no less worrisome. Remote transmission of data from systems monitoring the level of radioactivity is also interrupted, so it is impossible to follow what is happening on the spot. The IAEA also reaffirmed its concern on Tuesday about the “stressful and especially dire” situation of about 200 people working at the site, who have been unable to leave the premises since the Russian military forces took over the area in February. 24.