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The Norwegian Radiation Protection Authority (NRPA) has conducted a collaborative project to evaluate possible consequences for Norway from a hypothetical accident at the Leningrad Nuclear Power Plant (LNPP), Russia, as part of the work performed under the Norwegian Nuclear Action Plan.
Two of the three accident scenarios considered in the study were developed for the RBMK- 1000 reactors that are in operation at the LNPP and one scenario was developed for the new VVER-1200 reactors presently being constructed at the LNPP II site. For a worst case accident scenario, the predicted release is substantially higher from the old RBMK reactors than from the new VVER-1200 reactors.
Out of four combined accident/weather scenarios considered in this report, the scenario with the largest impact in Norway was considered to be a Chernobyl type accident coupled with real meteorological data from autumn 2001 with wind direction towards Norway and little precipitation.
For this hypothetical scenario, the total fallout of caesium-137 and caesium-134 were estimated to be 4.3 petabecquerels (PBq) and 2.8 PBq, respectively – which is about twice the total deposition in Norway after the Chernobyl accident. The highest deposition levels were predicted for Troms and Finnmark Counties in the northern part of Norway.
In order to assess the consequences for natural foodstuffs, the modelled radioactive fallout was coupled with data on transfer to the food chain and statistics on production and hunting. The assessment was limited to the terrestrial environment with a focus on wild berries, mushrooms and animals grazing unimproved pastures (i.e. game, reindeer, sheep and goats).
The largest consequences were predicted for semi-domestic reindeer, sheep and goat production. Up to 90 % of all semi-domestic reindeer could exceed the food intervention level for radioactive caesium in the first couple of years after the fallout, and 20-60 % likely to be above for years or even decades to come.
For lamb the number of affected animals in the first years could reach 300 000 (35 % of the total production), and as many as 100 000 could be above the intervention level in the following years.
The consequences for game in general were predicted to be low, but will to some extent depend on the regional distribution of the different species. For instance, red deer and roe deer are virtually absent in the most contaminated northern parts of Norway, whereas a considerable fraction of moose is found in these areas.
Berries from the southern part of Norway are not likely to be subject to gathering restrictions while berries in the northern part of Norway are at risk of being above the intervention level.
The activity concentrations in mushrooms will depend on species and affected areas. High accumulator species will probably be above the intervention level in the northern and south-eastern parts of Norway, while more popular species with lower accumulation are likely to be above limits in some northern areas only.
Based on the experience from the Chernobyl accident, the total predicted cost to society from a worst case hypothetical accident at Leningrad NPP could be considerable if there is a combination of a catastrophic accident and a meteorological worst case scenario