Raj Malhotra wrote:A very basic question.
. . .
Is it possible to jump to AHWR without sodium cooled reactors as some articles are skeptical of safety of sodium cooled reactors?
My answer to the above query would be as follows (without subscribing to the expressed skepticism about safety of sodium cooled reactors):
Naturally occurring Thorium (Th232) requires to be "seeded" with a fissile (odd-numbered) isotope such as U235, Pu239 or U233 for sustaining fission chain reactions aimed at generating heat energy in the fuel which in turn is converted to electrical energy. This would be true whether Th232 is used in an AHWR or in a FBR.
U235 is the only naturally occurring (in Nat U) odd-numbered fissile isotope. Since availability of Nat U is limited, use of U235 for large-scale Th232 utilisation may not be sustainable in the long run.
Pu239 (and higher odd numbered Pu isotopes) are produced while "burning" Nat U in PHWRs or LEU in LWRs. But again, the quantity of Pu so generated may not be adequate for bypassing the 2nd stage FBR altogether and directly getting into the 3rd stage of a large-scale Th232 programme (FBR or AHWR).
U233 is not a naturally occurring isotope and hence needs to be "bred" from Th232 by some means. The 2nd Stage FBR is one such way. However, if
U233 can be produced in sufficiently large quantities using the "out-of-reactor-breeding" concept, then it can possibly become a substitute / "additionality" for the 2nd Stage FBRs, for utilisation in the 3rd stage Th232-FBRs or AHWRs.
In this connection, you may like to check out the Chart titled "Three Stages of the Indian Nuclear Power Programme"
in page 5 of DAE's report A Strategy for Growth of Electricity Generation in India
(pdf) where Non-Reactor Breeding is shown as an activity.
I think India should
press ahead strongly with indigenous R&D and engineering in this field, without waiting for (or allowing) others to lead the way.