Stretching out the Ohio Class Submarines 20 More Years.

[seaman hornsby]

http://navaltoday.com/2017/06/14/bal...haul/?uid=1026

[cdivine]

Call me a lover of scifi / fantasy, but I would love to see the mast on these boats be a little more stream lined. I've never understood why the Russians have such smooth lines and our boats look like they were chiseled out of rock with such rigid lines. Before you make fun of me just know I'm an artist at heart so I pay more attention to aesthetics, but to be fair water does run quieter over a smoother surface unless I'm wrong and a square is smoother than an oval. Vertically speaking from a profile perspective that is.

[navy2000]

It is a standard that subs be refueled about 15 years after they are commissioned. The Ohio class SSBN's power plants run at a better rate of power use then that of an attack sub of prior years. Therefore the reactors are able to run a little longer in life time, thus making the refueling period every 20 years. Most fast attack sub only get about 30 years running time total minus the time of the refueling period of at least one year. So this means that the SSBN's will get 40 years of actual operational time total. As time goes by the sub can't keep going at flank speed for long times like they do when the reactor as a fresh source of power. I hope that some of this makes since for all to understand in a simple and basic way of saying. The reactor is some what like that of a battery the more that you use it, it slowly drains down to less amount of power that can be drawn from it. The average life span of a sub is about 30 years.

Duane

[rbr687]

I have to disagree with your statement that a nuclear powered sub cannot run at a flank bell for long times. The reactor (Rx) is not like a battery as you stated. The number one main Rx will try to meet the secondary power level demand as long as there is enough fissile material (fuel) in the core, therefore the Rx can and will operator at 100% power, for its core design life.
I think that you are confusing thermal efficiency and/or core operating life and/or something else. Most reactors are designed with a % full power level X time specifications. The early S5W (Submarine, 5Th generation, Westinghouse) reactor on the HMS Dreadnought was reported to have a core life of about 5,500 EFPH (Effective Full Power Hours). US Submarines that had a later S5W cores had a design of about 10000 EFPH and later refueled with a S3G core, with the same 78 MWt power rating and a core life of about 18,000 EFPH. Increasing the new operating period by 3000 EFPH.
A nuclear reactor will give you any power that is demanded from it at any time it has enough fuel, 100% power is normal the design power level of most reactors.
The reactor is not smart it will try to match the power that is demanded of it, ask and it will give, ask any newly qualified throttle man. The design reactor is stated above. If a 10000 EFPH Rx has a demand of 50% full power, the Rx will put out 50% full power for 20000 hours continually until the fuel is depleted, demanding 100% full power, the Rx output will be for 10000 hours, demanding 200% full power, the Rx output will be for 5000 hours if there were no other design limits stopping the operation at this power level.
A Sturgeon class sub was about 14% thermal efficient, where a commercial nuclear power plant is approximately 30 to 33% efficient due to the secondary re-heaters. The military isn’t really concerned with thermal efficiency on a submarine. There is no room for reheating systems on the sub. Boomers may have a higher secondary efficiency than an attack sub but I really don’t think so. It may be that boomers operate 3 months at 3 knots within its patrol area where the attack boat is not limited to a single small patrol area as a boomers or that the boomers that you are referencing may just have a different core design from the attack boats.

disclaimer:
Most of these number were retrieved from Wikipedia and the internet, but some specific information is nuc base knowledge that were recovered from the way back machine.

[navy2000]

All I am saying is that two of the subs that I served on before they went into overhaul ran slower at flank bell then they did after the overhaul in which they ran faster at a flank bell. Not just by a couple of knots, but more like 5. Yes you may consider the cleaning of the hull and new paint job, but in my thoughts that would only be a couple of knots like I had seen before for short dry docking periods.

Duane