Lesser of two evils - oil vs nuclear marine propulsion?

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Lesser of two evils - oil vs nuclear marine propulsion?

Postby zl2wrw » 05 Nov 2011, 00:30

Hi,

Is nuclear propulsion of commercial shipping a viable proposition for a future post-petroleum ecconomy?

Recently in New Zealand, the 47,000 ton "Panamax" class container ship MV Rena, ran aground the Astrolabe reef, which is about 12km off shore and about 22km from the port of Tauranga. It has since started to break up and is thought to have so far spilled about 350 tons of its fuel oil into the sea, resulting in the usual problems with oiled wildlife, oiled beaches, dead wildlife, bans on fishing and gathering shellfish, etc. It has been said to have been carrying about 1700 tons of heavy oil and 200 tons of marine diesel, but the salvors are trying to pump it off of the wreck as fast as they can.

Ignoring for the moment that current New Zealand law prohibits the navigation of nuclear propelled ships in New Zealand waters, and that there are no nuclear propelled container ships operating outside of arctic waters; If a nuclear propelled ship had run aground the Astrolabe reef and then suffered a meltdown and or been broken up by the action of the sea, would the environmental damage from the resulting release of radioisotopes to the environment be worse or less or about the same as that from an oil spill?

The main diesel engine on the MV Rena was about 22MW, so an equivalent sized nuclear propelled ship would probably have a reactor of about 70MWt capacity and a steam turbine to drive the prop?
Compared to nuclear power station reactors, I beleive that marine reactors typically use a smaller fuel load, but with a higher level of enrichment.


Regards
Ross Whenmouth
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Re: Lesser of two evils - oil vs nuclear marine propulsion?

Postby Matte » 05 Nov 2011, 19:04

Civilian ships could possibly be allowed to have 20% enrichment, but I am unsure. Though I fail to realise the implication of changing the enrichment from 5 to 20% or even higher (as long as you remain <85% I don't see any issues). A 60-100 MW reactor in a container vessel would be more than enough to propel it for 10-20 years without refuelling and the ship itself would need to be huge (!) to justify the cost.

I believe we will synthesise fuel for shipping before we start putting nukes on every containership (for political reasons and possibly finacial), the fuel synthesis technology is more than 20 yeas old but still too expensive ompared to fossil fuels.

As to any accident scenario, thanks to the reactor being small, the decay heat would be in the region of of a few hundred kWs which is easy to disipate through passive means if the ship is run aground. By the way, the number of submarine power plants scattered around the ocean floors is more than just a few... If the ship is lost at sea the powerplant would be submerged with the ship and would be cooled by the seawater and hence would not suffer a "melt down". The reactor wold probably rust away for a few years if left on the sea floor and would cause some issues, mainly political, the environmental impact would be minimal as the oceans are big (insert old gag about dilution).

NZ is a funny place when it comes to power generation, it is quite cheap to build geothermal electricity generating plants there (and there are a few scattered across the country) but any new ones tend to be scrubbed due to public opinion. I am guessing that the Kiwis, like everybody else, are very fond of coal...
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Re: Lesser of two evils - oil vs nuclear marine propulsion?

Postby NuclearSpeak » 21 Nov 2011, 12:12

I think the reason was simple- he'd never dealt with failure before. He was a Starfleet captain, what psychologists referred to as a "type A personality." He'd wished someone had clued him in on the fact that he might make a mistake. Just telling a young officer that would not be enough though; they would have to experience it. Therefore, he considered a test which presented that young officer with a situation that could not be solved. As T'Pol said, without resolution.
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