Submarine pressurized water reactor releases

Unit 421 was encased in concrete and as discussed earlier, a slowly degrading lifetime of 100 years was assumed for this containment barrier. A similar lifetime was assumed for the Furfurol(F) encapsulating the SNF. As the concrete barrier becomes more and more porous, activation products are released from the outside of the RPV. Then the breather hole into the interior of the RPV is corroded open in the year 2005, allowing fuel and interior SS corrosion to begin. The other RPV penetrations and barriers begin to open up in the year 2035, shown by the peak in release rates for the fission products, 370 GBq-a and actinides, 0.2 GBq-a L Coupled with the continuing steel corrosion, the total peak release rate is 370 GBq a.  

Novaya Zemlya Depression, unit 421, total activity release for Scenario A. 

After this, the fission product release rate falls away quickly as the more mobile atoms are released, until the year 2500. After that, the rate is follows the less soluble atoms in the fission product inventory. The actinide release follows this slow degradation rate as time goes on, it is seen however, that the overall rate of activity release is dominated by the activation products. Between the years 2500 and 3360, the release rate is of the order of 0.2 GBq-a.  

In the year 3360, the RPV has finally disintegrated, replacing the slow effective rate of corrosion for the interior of the structure by the faster BCR, and a short peak in fission and activation product release is seen, totalling 2.5 GBq a. After that, the fuel rapidly corrodes and is corroded away by the year 3385. 

The internal RPV cladding and the thermal shields are finally corroded away by the year 3710 in this last period, the release rates are dominated by the long-lived activation products at 1.6 GBq-a.  

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