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PostPosted: Nov 09, 2014 7:07 pm 
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Say we have a 2 fluid breeder thorium MSR simmering away in a tank of hastelloy, and someone puts a hole in it - like drills through the wall into the thorium fluoride blanket. I presume the molten salt will dribble out, cool and solidify, and that rays will escape out of the hole. This is called 'shine', yes? Would it be a mix of alpha/beta/gamma/neutron? And is there a straightforward way to estimate the effective radiological hazard of this based on the required environment for U233 breeding in the blanket salt?

Thanks in advance.


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PostPosted: Nov 09, 2014 11:54 pm 
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Doctor Osk wrote:
Say we have a 2 fluid breeder thorium MSR simmering away in a tank of hastelloy, and someone puts a hole in it - like drills through the wall into the thorium fluoride blanket. I presume the molten salt will dribble out, cool and solidify, and that rays will escape out of the hole. This is called 'shine', yes? Would it be a mix of alpha/beta/gamma/neutron? And is there a straightforward way to estimate the effective radiological hazard of this based on the required environment for U233 breeding in the blanket salt?

Thanks in advance.


That someone would have to enter the hot-zone of the reactor while it is in operation in order to put that hole there. (incidentally this could be considered a security feature since an attacking agent is very likely to die before he got anywhere near being able to damage the reactor)

But say the reactor system sprung a leak due to component failure, personnel should not ever need to enter that zone during operation and access would be made during a shut down and the radiation in the containment returns to a non-hazardous level for the repairs.


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PostPosted: Nov 12, 2014 3:01 am 
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Two fluid, or one fluid would make little difference in this scenario. First, design of the hot cell for the reactor components would not have a lot of room for people to fit inside. Most of the equipment would be designed to be removed for repair rather than have a person go in to do work. This is dictated by the fact that operating, and even shutdown, temperatures are in the range of 400 to 700ºC, and very high radiation levels. Even shutdown, and drained of fuel interior radiation levels would be too high for people to work in the pace. You would need an asbestos overcoat, lead underwear, and work VERY fast :lol: .
Part of the design requirements would be how to get rid of heat from fission products if an accident could leave fuel, or blanket salt on the floor of the reactor compartment.

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PostPosted: Nov 12, 2014 9:36 am 
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For estimating the radiological hazards from the blanket salt, you would need to look up U233's predecessor isotopes of thorium, protactinium, and a trace amount of U232.


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PostPosted: Nov 12, 2014 2:58 pm 
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Suppose someone with horizontal drilling experience drills into your reactor from a rig a mile away...


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PostPosted: Nov 28, 2014 3:25 am 
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Doctor Osk wrote:
I presume the molten salt will dribble out, cool and solidify, and that rays will escape out of the hole. This is called 'shine', yes? Would it be a mix of alpha/beta/gamma/neutron?

Ignoring the difficulties of drilling a hole, it seems safe to assume that such a leak from the blanket would cause the reactor to shut down (due to lack of neutron reflection from the blanket).
So you won't have much neutron 'shine' (there will be delayed neutrons, even long after shutdown, due to photonuclear reactions involving gammas from fission products and Beryllium in the salt: in the attached figure, blue is the trace for Be9(g,n2a) and red is for D(g,np).
Not much alpha/beta either, from the empty blanket -- lots from the stuff dribbled out (the wall of the container for the core will stop all alpha/beta).
Also lots of gammas, from the leaked stuff and from the core still in place (presumably). But likely to be much less than what it was before the reactor shut down.


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PostPosted: Dec 07, 2014 3:17 am 
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Cthorm wrote:
Suppose someone with horizontal drilling experience drills into your reactor from a rig a mile away...
The salt leaks out of the vessel, down to the catchpan, into the drain and to the drain tank where it remains safely cooled by its propery designed natural heat removal system. Then the reactor vessel is washed, repaired (with needed repairs to the graphite core), refilled and restarted. Or not if the damage is too great.

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