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PostPosted: Sun May 13, 2007 12:02 pm 
Werner wrote:
Pure water does not become radioactive.



Water can be chemically pure and made from radioactive isotopes of hydrogen or oxygen.


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 Post subject: Engineering Plants
PostPosted: Sun May 13, 2007 12:35 pm 
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I like the idea of turbo-electric drive. If you recall, this concept was used on USN battleships in the WWI era. It had some real advantages: eliminated the need for gearboxes to reduce shaft rpm. Eliminated the need for reverse-rotation turbines. Allowed better compartmentation of hull, better watertight integrity, shorter shaft runs, better distribution of boiler and engine rooms. Possibly reduction of vibration.

Disadvantages: Weight of generators and motors; use of high-voltage electricity in a moist, corrosive environment. Need for power-switching control equipment in a protected location.

If drive units are going to be located on pods (which I am not at all sure is even a good idea in a warship), electric drive is probably the only practical method. Long vertical driveshafts mechanically driven from within the hull would certainly be vulnerable to battle damage. This would also seriously increase the draft of the ship.

I always liked the Kirov hybrid drive: it would provide a redundancy in case of reactor failure.

The high-voltage side of the electric drive would of course need to be kept as physically small as possible. But even here, the potential exists for redundant, alternate hv. cable routes between generators and motors to circumvent battle damage.

My ideal concept: nuclear steam turbine-electric drive. Steam generator boosted by independent oil-fired boilers, separate from reactor system, that could also be used as an emergency power source for propelling ship at reduced speed. Multiple-shaft screw drive in conventional layout. Electrically-driven internal bow thrusters to aide docking and steering in case of rudder failure. Dual non-balanced rudders located in thrust current of inboard screws. Dual hydrodynamic stabilizers on each side of hull.

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PostPosted: Sun May 13, 2007 1:06 pm 
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Anonymous wrote:
Werner wrote:
Pure water does not become radioactive.



Water can be chemically pure and made from radioactive isotopes of hydrogen or oxygen.

Let's be realistic: for the purposes of this discussion, a reactor at the bottom of the sea does not make the sea water radioactive, nor do it's components or by-products represent a significant danger to the cultures who live on those waters or use them for commerce or industry unless they are determined to recover the wreck or work within a few meters of it for some purpose.

Specific production of a specie of water from radioactive isotopes would be the kind of thought experiment only of interest to intractable pedantics like Chuck.

The public's perception of the dangers of nuclear power are based on a deeply ingrained ignorance reinforced at nearly every opportunity by the press and other media, who seem specialized for getting the facts wrong in general, and on scientific facts in particular.

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PostPosted: Mon May 14, 2007 8:03 am 
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Werner said:
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The public's perception of the dangers of nuclear power are based on a deeply ingrained ignorance reinforced at nearly every opportunity by the press and other media, who seem specialized for getting the facts wrong in general, and on scientific facts in particular.


Do you mean that the radioactive fallout from American nuclear testing in the Pacific did not help give birth to Godzilla??!!?


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 Post subject: Why go deep?
PostPosted: Mon May 14, 2007 9:35 am 
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The gist of what I have been able to deduce from what I am hearing and reading indicates that the focus of future USN strategy will be on preparation for littoral warfare. If we are to continue to be the world's policeman, we need to be gearing up for close-in missions: amphibious landings, fire support, close-in patrols, etc.

In light of this, I cannot see the wisdom of using podded drive units 40' below the surface. Increasing the draft in this way would make the ships less suitable for this type of shallow-water combat. Imagine the problems if a warship were to hang up on a reef while under attack.

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PostPosted: Mon May 14, 2007 1:26 pm 
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Werner wrote:

Specific production of a specie of water from radioactive isotopes would be the kind of thought experiment only of interest to intractable pedantics like Chuck.



:Mad_6: Intractable pedantic? You wound me.

:mad_2: :big_grin:


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PostPosted: Sun May 27, 2007 6:13 pm 
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Uh, what does a nearby nuke generating EMP do to an all electric ship? Blooey, I'd say... what does it cost to shield a ship from EMP?

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PostPosted: Mon May 28, 2007 6:35 am 
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No Godzilla, just some nice and friendly cases of radiation sickness , cancer and birth defects in a large number of people, including military . Godzilla's inspiration may have been the very real story of a japanese fishing boat which came into contact with fallout from a nuke test in the pacific in the 1950's. The ban on atmospheric testing of 1962 between the US and the SU had nothing to do with public misconceptions about radiation safety (both US and SU public were still in their atoms for peace phase) and a lot with 17 years of hard experience with the effects of radiation on their own personnel.
Back to the original subject, we don't know the effects of a nuke warship being destroyed in war at sea as it has not happened yet. Most submarines sunk either had their reactors switched off or a very heavy shielding mechanism in a hull designed to take a lot of pressure. The hull structure of a surfcae warship is very defferent and depending on how many air is left when leaving the surface will of will not break up during the sinking.
One thing about Werners' remarks, most radioactive elements in a reactor core are heavier than water but not all of them. Lightwater reactors like the ones used in nuclear surface warships create a lot of lighter radioactive elements by neutron flux on parts of the reactor and which are part of the primary cycle (the parts of the reactor that are in contact with the core). Many of these like radioactive radon are carcinogenic. This becomes worse with time so if any nuke carrier is to be sunk it had better not be Enterprise.
[quote="Jack Ray"[/quote]

Do you mean that the radioactive fallout from American nuclear testing in the Pacific did not help give birth to Godzilla??!!?[/quote]


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PostPosted: Mon May 28, 2007 11:46 am 
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Your reactor-generated Radon has a molecular weight of 222 and will sink into the ocean substrate like a hot knife in butter.

Natural Radon was rarely a problem in houses with basements where the Radon is kept within millimeters of the floor and transfers some radiation to dust motes which are light enough to be drawn into the heating/cooling system.

The flow model for the ocean would be quite different.

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PostPosted: Tue May 29, 2007 3:14 am 
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Werner wrote:
Your reactor-generated Radon has a molecular weight of 222 and will sink into the ocean substrate like a hot knife in butter.

t.


While I hate to be the intractabe pedantic, I feel obliged to play the role you assign me.

:big_grin:

Since we are talking about sinking in the ocean, I think we can presume that we are not talking about an ideal gaseous substance. Therefore the density does not depend directly on molecular weight.

:wave_1:


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PostPosted: Tue May 29, 2007 3:54 am 
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You're absolutely right. The flow model for the coaean is very different, so is the atmospeheric model for the air above it. We are talking about some kind of catastrophic hull failure in a surface warship, very close to the atmosphere. And as chuck remarked the molecular weight of radon (and some other decay products) does not matter. And you did not take note of the rest of the primary cycle materials. Some people do not seem to understand that any reactor which is depending neutron flux for keeping up the chain reaction will contaminate everything in the structure around it. This is the main reason for the eleborate shielding you can see around shore based nuclear reactors. I don't see why a catastrophic failure of the hull of a nuclear surface warship would somehow magically contain all radio active matarials and bury itself in a few miles of ocean. Aside from the fact that nuclear surface warships have mainly been fighting in wars in relatively shallow waters like the Persian Gulf and the Adriatic (which does have ocean depth parts but which is mainly very shallow) over the past 20 years.
[Radon has a molecular weight of 222 and will sink into the ocean substrate like a hot knife in butter.


The flow model for the ocean would be quite different.[/quote]


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PostPosted: Tue May 29, 2007 10:08 am 
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Is six feet or so of water not an ideal neutron moderator?

If I had a litre of Radon and a litre of water and mixed them in a 2 litre jar, what would the result be? Surely the material with the heaviest weight per volume would occupy the bottom layer. No magic will occur.

I think the fact that Radon is a gas at room temperature would not inhibit it's sinking under the much lighter sea water. Nor would it inhibit Radon entering solution with the water.

Would not (in the abstract) a Radon atom (weight 222) sink much more quickly than, say a mere atom of lead at 82? I had always heard the molecular weights of the isotopes would greatly discourage their mixing in the water column, and will instead be buried under sediment in a few years, especially at benthic temperatures and pressures.

The Russians have always used this excuse when dumping surplus nuclear materials in the Arctic Sea.

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