Radioactivity - The Changing Arctic Environment: The Arctic Messenger - page 69

that time of about 2.8 × 10 15 Bq of 90 Sr and 3.1 × 10 15 Bq of 137 Cs, together with other
long-lived fission and activation products. Now more than 25 years after the accident, 90 Sr
and 137 Cs dominate the fission-product total inventory and it is estimated that most of the
activation products will have decayed before corrosion leads to significant releases to the
environment. Two torpedoes with mixed uranium/plutonium warheads were also on board
and were estimated to contain approximately 1.6 × 10 13 Bq of weapons-grade plutonium.
The 1998 AMAP assessment reviewed monitoring data up to 1997. Surveys in late
1993 that included Russian, Dutch and U.S. scientists detected cracks in the hull of the
ship, a hole in the torpedo compartment and leakage from one of the warheads. These rup-
tures were subsequently sealed in 1994. Monitoring found that some leakage of 137 Cs was
detectable through a reactor ventilation tube at an annual rate of less than 0.5 TBq and
modelling suggested this rate of 137 Cs release would continue for the next 2,000 years. The
nuclear warheads are not as well protected as is the submarine reactor and could therefore
corrode more quickly. However, the released plutonium is likely to strongly bind to sedi-
ment and therefore most contamination will remain close to the wreck. At the wreck site,
very little vertical mixing of the water column has been detected, and at the same depth,
a slow horizontal deep-water current moves towards the north-east. To sum it all up, the
Komsomolets is not considered to represent a significant hazard to humans now or in the
future.