About Zaporozhye NPP Accident Prediction Models

In recent days, we could see on social media some images and videos with ‘prediction of consequences of a serious nuclear accident in the Zaporozhye nuclear power plant’.
Here’s an example for August 29:

Fig. 1 – Image showing ‘Summary dose from all sources, potential for 14 days’
Fig. 2- Video showing ‘Effective doese from a cloud of all nucleides [mSv/year]

So, what do we see on these Energoatom videos and images?
According to their (very sparse) description, it shows ‘the consequences of a serious accident in the Zaporozhye nuclear power plant’.

However, that’s not very descriptive on what a ‘serious accident’ means. To find out more, we refer to the description on the Energoatom website. They describe it als follows:

«According to the operating Organization of SE NNEGC Energoatom, we present a forecast of the consequences of a potential accident for power unit No. 6 of ZNPP under the conditional scenario “complete loss of power supply with destruction of the protective shell”, made using the European Rhodes system, the model of atmospheric dispersion – DIPCOT, the source of meteorological data – Not Set and the parameters of the emission source, which corresponds to the total emission on the INES – 7 scale.»

Energoatom, 28.08.2022

To learn more details, which I have found not to be described anywhere on their website, we refer to the heading and legend of the map. They are different in the video and on the sill image they posted.

For the video the description title reads [in part]:

Effective dose from a cloud of, all nucleides [mSv/year].

See video attached above in Fig. 2

The legend’s classes [or buckets] goes up to 1,000 mSv/year which is 1Sv [colored red, bucket width is from 100 to 1,000 mSv, but the maximum they predict in one prediction is 103mSv/year, slightly above the lower bound of the bucket.

For the image the description title reads [full]:

«Summary does from all sources potential for 14 days»

See image attached above in Fig. 1

The legend’s classes [or buckets] goes upt to to 10,000 mSv/year wich is 10Sv [colored black, bucket width is from 1,000 to 10,000 mSv, but from the map we see that it is not reached, instead they have areas of dark and light blue [the latter not appearing in the legend, and the former corresponding to the class given in the video [100 to 1,000 mSv/year], a maximum value is not given here, but we can safely assume it to be the same as given in the video.

As a comparision, Wikipedia gives these radiation dose examples:

  • 80 mSv 6-month stay on the International Space Station
  • 250 mSv 6-month trip to Mars
  • 1Sv Maximum allowed radiation exposure for NASA astronauts over their career

The Candian Nuclear Safety Commission gives the following values for natural background radiation in cities of Canada [modified 2020-12-22]:

  • Vancouver [lowest value] 1.3 mSv/year
  • Winnipeg [highest value] 4.1 mSv/year
  • Canada [average] 1.8 mSv/year

The also give background radtion levels for other parts of the world

  • US 3.0 mSv/year
  • Kerala coast, India 12.5 mSv/year
  • Worldwide average: 2.4 mSv/year

In Canada the five year dose limit for nuclear energy workers is 100 mSv and for ISIS astronauts/cosmonauts they give 150 mSv

In conlusion, the images videos are supposed to tell us what the summary dose of radiation during 14 days will be, if a serious nuclear accident occurs in block six of the ZNPP with complete loss of power and breach of the outer hull.
It says nothing about any long term effects of what they consequences will be on the people living in effected areas, i.e. what the type of radiation will be and how long it will persist in the air, ground, and water.
The video is informative, while the image is not – the latter is given for maximum scare effect in my opinion.