AboutDr. Kent Welter Expertise Nuclear Reactor Safety Analysis, Generation IV Reactors, Thermal-Hydraulics, Nuclear Analysis, Environmental Aspects of Nuclear Power, Sustainable Development, Nuclear Engineering Education and Training, Knowledge Management, and Climate Change.
Experience Ph.D. in Nuclear Engineering from Oregon State University (2002). Experience as a Reactor Systems Engineer at the United States Nuclear Regulatory Commission. Executive Committee Member, Enviromental Sciences Division, American Nuclear Society.
Question QUESTION: Hello and thank you for your time. You may be interested that I,like you,volunteer here under the screename tbaarr and may be able to assist you in making a better return on your investments if you feel like reading my answers. NOW to my question. I am an ex electrical engineering student who was supposed to work at the moscow ohio nuclear plant that was never completed due to contractor issues and finally went coal fired. My question is in parts.
1 Is not the temp that is permenantly put out by spent fuel still around 400 degrees?
2 This fuel is stored in lead lined vaults so its fairly safe for people to be near.
3 Why is it necessary to create new reactors that require new rods, When the spent fuel vaults could simply be placed around a sealed water supply and easily cause hat supply to boil and turn into steam.
That steam heat could be easily be transferred through a sealed heat exchanger to a second water supply that could go thru the typical superheaters used in coal fired plants and finally turn the turbines.
Ie no worry about meltdowns as the fuel is stabilized in a vault.
The piping could be double strength and be replaced at intervals by robots so men are not endangered.
Ie no steam leaks.
No need to buy new fuel as the existing waste fuel for the last 30 years should suffice.
Your thoughts and input is appreciated.
thank you for your time
chuck weber
ANSWER: Hi Chuck,
Thank you for taking time to submit your answer at allexperts.com! Please see below for response to your questions.
1. Is not the temp that is permenantly put out by spent fuel still around 400 degrees?
3. Why is it necessary to create new reactors that require new rods, When the spent fuel vaults could simply be placed around a sealed water supply and easily cause hat supply to boil and turn into steam.
Good question! However, when you place water around the rods, it will cause the assemblies to go critical causing a fission reaction. Just like in the core of an operating reactor. This critical chain reaction would heat up the fuel and fail the cladding.
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QUESTION: I am not saying put water around the rods. I am saying put the storage vault that is totally stable next to a tank. the rods are still inside the vault.. the vault is the heat source
the rods never come into contact with the water as they are still inside the vault. the water is inside a sealed system. That system is heated to boiling point by the heat transfer through the air caused by placing the vault next to the water tank
ANSWER: OK. The tank would not reach boiling temperature. Only the cladding, right next to the fuel inside the dry cask, can reach temperatures up to 400C. The temperature on the outside of the storage vault or dry cask is essentially ambient temperature (70 F).
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QUESTION: A final thought
assuming this example the cadding is say 1 foot thick
assume a point in the cadding 6inches away from the spent fuel is still around 240 degrees could not a metal pipe say filled with mercury or some conductive liquid metal/fluid be placed at this point and be able to draw heat off the cadding to then be sent to the water. this then would be the source to boil the water.
The fluid is never in the rods and the pipe is removable to maintain inpections for integrity.
again using robots, for human safety.
this is my last try, I thank you for your time. if you have a place I can go to on the web that shows a picture detail of a vault.
I would appreciate it.
Answer I like your thinking, but it still won't work :( For effective heat transfer, you would need a fluid medium around the fuel. Placing a pipe near warm fuel rods would be so incredibly inefficient. In addition, you would have to postulated or safety analysis purposes that the pipe would break and liquid metal would poor into the dry cask. In this postulated accident scenario, the liquid metal would pool around all the fuel rods and have a potential to cause a re-criticality event. Not good. Anyway, your concept of harnessing the heat from dry casks is novel to say the least. It got me thinking a little about the concept. The issue will always be that as you start to add new systems to the dry cask to harness the heat, the safety analysis becomes more complex and there could be a lot of technical issues that would need to be addressed.
