How to discuss this, and not break any rules.....
Okay, the control rods, when de-engergized, revert automatically to a fully inserted position. This is ALL the control rods, not just the SCRAM group. There is sufficient nutron attentation to adequately ensure a core shutdown even if one or 2 where to 'stick' at some position not corrosponding to full insertion.
The reactor vessel is probably the single strongest component on the submarine. In a hull collapse the primary cooling lines will, in all proabability, be severed from the contaiment vessel. This will make the vessel non-collapsable as internal pressure will be equal to sea pressure. This is important for as long as the containment vessel is intact the control rods will be maintained in the proper configuration to ensure continued core shutdown.
The worry then is corrosion of the fuel matrix and the subsequent release of radioacive material. Again, as long as the containment vessel is intact this should not result in the significant spread of contamination as any corrosion products should be maintained inside the containment vessel.
The corrosion of the containment vessel, due to the nature of the materials used, will be very slow. If the vessel lays at a considerable depth the corrosion rate will be further reduced by the low free-radical and oxygen content of the seawater at extreme depths. If it is in shallow water where corrosion can be a significant factor then means can be made to bring the containment vessel to the surface. Remember, we once dang near raised a Golf class sub many years ago. The reactor vessel is significantly smaller and lighter than a sub
With that being said here is another thought track.
If the submarine in question were to be damaged, say by a torpedo, and the reactor vessel is ruputed distupting the control rod configuration. Well, that would be bad. With no control rods the reactor would pretty much be uncontrolled and the resulting fission products would be scattered to the seas and currents. We are talking Chernobyl of the seas here. Massive contamination on the order of months and years. On the bright side, that is an absolute worse case. It would be an incredible lucky (unlucky??) explosion that would disrupt the control rod configuration and NOT disrupt the core configuration so much that criticality could be maintained on any small scale, let alone a scale large to make significant measurable contamination.
|