Radiation spikes seen during the Russian capture of the Chernobyl nuclear power plant in Ukraine were initially put down to tanks stirring up contaminated dust, but experts now believe this contamination may never have happened. Instead, interference between wireless radiation sensors and unidentified military equipment may have been to blame. But it may be impossible to confirm the true explanation because computer equipment in monitoring laboratories was looted when Russian troops left, a scientist working at Chernobyl says.
On 25 February, the day after Russian troops took control of the power plant, Ukraine’s nuclear regulator reported that radiation readings of up to 32.3 microsieverts per hour were probably caused by “movement of a large number of heavy military equipment through the exclusion zone and the release of contaminated radioactive dust into the air”.
at the University of Salford, UK, and his colleagues have since been able to extract some data from automatic wireless monitoring systems at Chernobyl, despite the chaos on the ground and the evacuation of the site, which left scientists employed to monitor the site unable to take definitive samples.
Advertisement
A large network of 67 sensors known as the Comprehensive Radiation Monitoring and Early Warning System (CRMS) is installed across the Chernobyl power plant and its surroundings. These sensors communicate wirelessly with a base station at the plant.
Wood says the pattern of radiation spikes seen rules out a rolling convoy of military vehicles as the pattern wasn’t clustered around any particular route. The team also calculated whether the material in the soil was strong enough to cause the spikes, and concluded that even with conservative estimates it wasn’t. Because the spikes show no clustering around any of the contaminated storage areas, the team rules out a leak as the cause.
at the University of Salford, one of the co-authors of the paper, says that the research used estimates that erred on the side of higher contamination levels, and simulated 3 centimetres of topsoil being thrown into the air, but still couldn’t replicate the readings found at Chernobyl. “You would not see the increase in the spikes we saw due to soil being put in the air,” he says. “It’s just not feasible. The spatial pattern just doesn’t make any sense for a leak, so it seems to suggest it’s not that either.”
Wood agrees, and says that the cause could instead have been some type of military equipment that interfered with the communication between the sensors and the base station, or the operation of the base station itself. The latter option would explain the lack of a geographical pattern to the spikes.
“No way do I think it’s feasible that it was dust generated as a result of movement of vehicles,” says Wood. “We’ve hypothesised that the cause may well be to do with electromagnetic frequencies being used by the military, and it could be Russian or Ukrainian military around that time, actually interfering with the reception of data.”
There is also an older network of 28 gamma radiation sensors at Chernobyl known as the Automated Radiation Monitoring System. These are physically wired to the central base station rather than transmitting wirelessly like the CRMS. Wood says it appears that more of these sensors may have remained operational as backups for wireless sensors that went offline, and that if this were the case, their readings tended not to show the same spikes, which supports the idea that wireless interference was responsible.
Maxim Saveliev at the Institute for Safety Problems of Nuclear Power Plants in Chernobyl told 91av that wireless sensors at the site should theoretically be safe from interference and that the dust theory shouldn’t be ruled out. He added that it would be hard to verify any explanations definitively because computer equipment logging these monitor readings was looted from laboratories as Russian forces retreated on 31 March.
Even those roads considered safe at Chernobyl can have contamination risks, he says. “The contamination in the exclusion zone is very insidious,” he says. “In my personal experience, we used a ‘safe’ asphalt road on the east of the Pripyat river several times, and one time in the early spring we contaminated the car significantly. There are ‘hot points’ that may migrate also on the wheels and body of transport vehicles.”
at Bangor University, UK, says the paper seems plausible, but is “very data light”. The team behind the research agrees that concrete answers will only be available if scientists are able to return to the site and recover comprehensive data.
at the University of Liverpool, also in the UK, says the paper presents a strong scientific argument, but he also points out that there is a lack of data and no way to verify the findings directly due to the situation in Ukraine.
Reference:
