Thorium Based Indian Nuclear Programme

[anant_s]

Excellent thread XiNiX, but there are a lot of factual error which i wish to point and correct:

1. First of all not all radioactive materials in actinide series are fissile. Isotopes like U235, U233 and Pu239 undergo fission (in Thermal and fast neutron regime respectively) but isotopes like U238 and Th232 (Thorium talked in this thread) are fertile material. This means they have to be converted to a fissile material.

2. Thorium is used as a blanket and converted to an isotope U233 by following reaction

90Th232 + 0n1 (Neutron) -->91Pa233 + Beta --> 92U233 +Beta (first number is atomic number, second is mass number)

92U233 is a fissile material which can be used in thermal reactors (slow neutron reactors using moderator) and then used for power generation.

3. However the problem is that this conversion can be done in a fast breeder reactor (these are called breeder because they convert a fertile material into fissile material, thereby generating fuel), only one such exists now in India, another one is in construction. Also one requires advanced, fuel separation or processing capabilities to recover 92U233 for further use.
4. Hence before, U233 reactors come into existence, India would need to develop large fleet of Plutonium (94Pu239) powered reactors to breed and convert Thorium.
5. India has world's largest thorium reserves and if this can be used on commercial scale, a huge potential for power generation through this route exists.
6. There is an inherent problem with Thorium that it emits alpha radiation and is hence difficult to handle even in un-irradiated form.
7. Design work on a vertical thermal reactor to be used as converter for Thorium to U233 is underway, but Thorium powered commercial reactors are still atleast two decades away.
8. However the good thing is the projects have steady funding and as projected when Uranium reserves start to deplete after 2075, we would definitely have a new source of power at our disposal.

 

[Jayanta]

We have the worlds largest reserves of thorium.Can this thorium be used in nuclear weapons(instead of uranium or plutonium)?

The answer is yes it can be and has been used. It seems it has several advantages over U-235 based reactors...especially the enriching part which is tricky and expensive. Naturally occurring isotopes of thorium can be used as fuel....I am not 100% sure of the claims...but that's what written in wikipedia.... but use of thorium is definitely possible...and India have huge reserves of it...which can be exploited.

Liquid fluoride thorium reactor - Wikipedia, the free encyclopedia

http://en.wikipedia.org/wiki/Thorium

India's Kakrapar-1 reactor is the world's first reactor which uses thorium rather than depleted uranium to achieve power flattening across the reactor core. India, which has about 25% of the world's thorium reserves, is developing a 300 MW prototype of a thorium-based Advanced Heavy Water Reactor (AHWR). The prototype is expected to be fully operational by 2013, after which five more reactors will be constructed. The reactor is a fast breeder reactor and uses a plutonium core rather than an accelerator to produce neutrons. As accelerator-based systems can operate at sub-criticality they could be developed too, but that would require more research. India currently envisages meeting 30% of its electricity demand through thorium-based reactors by 2050.

 

[anant_s]

This Thorium can also be used to make nuclear weapons..?

Please everyone. Thorium CANNOT BE USED AS A DIRECT CYCLE FUEL.
You need to convert thorium to 92U233 before being used in a power reactor. Even the Liquid Metal reactor being talked in this thread is a converter reactor to obtain U233 from thorium blankets. Similar technology of Th232 to U 233 conversion is being done in Fast reactors (Pu239 powered).

I request interested members to read Nuclear Engineering textbook by Glasstone and Sessonsky and remove this misconception of Thorium as a Direct cycle Nuclear Fuel.
Further there is no such thing as Thorium Weapon.

 

[neehar]

atlast a cleaner,effecient and long term solution for our growing energy demands and rising economy

 

[Rangila]

There is an inherent problem with Thorium that it emits alpha radiation and is hence difficult to handle even in un-irradiated form.

Source: http://www.defence.pk/forums/indian...indian-nuclear-programme-5.html#ixzz2MGi0izTF

What about Uranium which also emits Alpha? U-238 emits Alpha, so does U-235!

 

[anant_s]

What about Uranium which also emits Alpha? U-238 emits Alpha, so does U-235!

No U235 donot emit alpha on their own. It is only when they undergo fission, fission products are formed that emit alpha. Thorium however undergoes spontaneous decay and it keeps emitting alpha even in its natural form without any neutronic interaction.
Further the alpha is pretty energetic and hence posses a lot of hazard to people handling them, on the other hand natural uranium prior to its charging in a reactor core can easily be handled by hand.

Thorium Decay Chain

Infact one of the biggest problem with Th232 is an intermediate isotope U232, which also emits hard (high energy gamma) which is required to be taken care of by high density shielding either in fuel re-processing or fresh fuel bundles.

 

[Rangila]

You did not answer my question in a proper and adequate way. Look below what I said:

What about Uranium which also emits Alpha? U-238 emits Alpha, so does U-235!

Source: http://www.defence.pk/forums/indian...indian-nuclear-programme-5.html#ixzz2MHbcYwPu

U-238 is a natural uranium which emits Alpha, thats what I said. Why are you silent on that. something that is the fact.

 

[anant_s]

You did not answer my question in a proper and adequate way. Look below what I said:



U-238 is a natural uranium which emits Alpha, thats what I said. Why are you silent on that. something that is the fact.

Rangila, the basic decay modes for any isotope are alpha, beta and neutron decay for almost all lanthanide series elements, so statistically speaking all isotopes undergo one or more types of decay with varying degrees of probability. However alpha decay we are talking here is in terms of energy carried and consequently the damage caused to human tissue. the energy carried by alpha is different in all cases and as a thumb rule higher the energy carried, more is the damage caused by ionization. Gamma damage caused is also similar with only difference being that it is electro-magnetic in nature and hence higher penetration.
Alpha particles can be shielded by very easily.
Again coming back to teh point of thorium, the two hazards as i've already mentioned are due to alpha release and secondly by gamma released from U232 (impurity in thorium).

Infact if you read early history of Thorium converter reactors, one major engineering problem encountered was separation of 92U233 from irradiated thorium bundles as it posed a far higher radiation hazard than Irradiated Uranium bundles (Plutonium separation).
I hope i'm able to put my point across.

Heres an interesting read for very early Plutonium separation plant development in US
http://www.inl.gov/publications/d/proving-the-principle/chapter_11.pdf

 

[Rangila]

YOU SAID:

There is an inherent problem with Thorium that it emits alpha radiation and is hence difficult to handle even in un-irradiated form.

I SAID:

What about Uranium which also emits Alpha? U-238 emits Alpha

YOU SAID:

Rangila, the basic decay modes for any isotope are alpha, beta and neutron decay for almost all lanthanide series elements, so statistically speaking all isotopes undergo one or more types of decay with varying degrees of probability. However alpha decay we are talking here is in terms of energy carried and consequently the damage caused to human tissue. the energy carried by alpha is different in all cases and as a thumb rule higher the energy carried, more is the damage caused by ionization

Thorium decay has lesser degree of decay value than U-238 (Natural uranium)

T-232 CA (calculated activity) Curie 1.101E-04 - Decay Energy (MeV) 4.083
U-238 CA (calculated activity) Curie 3.340E-04 Decay Energy (MeV) 4.270

hence on above factor, your statement on Thorium is of little value.

There is an inherent problem with Thorium that it emits alpha radiation and is hence difficult to handle even in un-irradiated form

 

[Inqhilab]

India hosted the first ever conference dedicated to Molten Salt Reactor technology.​

It is clear that in India there is an increasing interest in true molten salt or liquid fuel concepts.Foreign attendees were very surprised by the scope of both interest and development already underway at BARC (Bhabha Atomic Research Centre) on MSR technology.The conference had a about 200 attendees, a couple dozen of us from outside India. About half the talks and 2/3rds the 50 or so papers were from Indian researchers..

Site about this conference:
Conference on Molten Salts in Nuclear Technology (CMSNT-2013) | Molten Salt India

Conclusion:

AHWR(Advanced Heavy Water Reactor) have immense technological synergies with MSBR except on-line reprocessing therefore On-going R&D programmes for AHWR(Advanced Heavy Water Reactor) will benefit MSBR development. Besides, a modest program on MS & LBE coolant related research have been initiated along with physics studies in BARC.