Investigation of the marine environment around the nuclear submarine "Komsomolets" 6.-10. July 2019 (No. 9-2019)

Sammendrag

In July 2019, a re­search cruise to the wreck of the nuclear submarine “Kom­so­mol­ets” was car­ried out with RV “G. O. Sars” and the ad­vanced Re­mote­ly Op­er­at­ed Ve­hi­cle (ROV) Ægir 6000. The ex­pe­di­tion was organised un­der the Joint Nor­we­gian Rus­sian Ex­pert Group for in­ves­ti­ga­tion of radio­ac­tive con­tami­na­tion in Northern Areas. Using the ROV, the con­di­tion of “Kom­so­mol­ets” was vis­u­al­ly doc­ument­ed and sam­ples of sea­wa­ter, sed­i­ment and bio­ta were tak­en at spe­cif­ic lo­ca­tions in the immediate vicinity of the sub­ma­rine. Onboard ana­lys­es of sea­wa­ter sam­pled di­rect­ly from the ventila­tion pipe where re­leas­es have pre­vi­ous­ly been doc­ument­ed, showed ac­tiv­i­ty con­cen­tra­tions of 137Cs be­tween <8.0 and 857 Bq/l. This indicates that releases from the reactor are still occurring, 30 years after “Komsomolets” sank. Based on our observations, the releases of 137Cs from “Komsomolets” to the marine environment appear to vary in amount and duration. Samples collected during the expedition will now be further analysed in the laboratory for 137Cs, 90Sr, Pu-isotopes and other radionuclides as well as trace metals to further understand the nature of the releases from the reactor and to determine if any plutonium from the two nuclear warheads has been released into the marine environment. The results will be compiled and published in a report under the Joint Norwegian Russian Expert Group by the end of 2020.