HMS Vanguard to get new nuclear core
 

The old girl was launched in 1992 so she was probably just about due a replacement anyway.

http://www.bbc.co.uk/news/uk-politics-26463923

About time the suits stopped screwing around and figured out what the next stage for the deterrent is, instead of kicking the ball down the road, and then being screwed in a decade when we need new Boomers and we don't have any.


I know, I know, more chance of winning the Euro.

Dont be too sure, I won £25 last Saturday :)

As a former Nuclear Engineer these things interest me. What concerns me is I think you all are being fed a crock of you-know-what.

First of all, what are cooling waters? There is a primary side to a reactor and a secondary side. The primary side is the high pressure side that is contained within the reactor compartment. The secondary side is the side that leaves the reactor compartment and enters the engine/machinery rooms. The only interface between primary and secondary sides are the steam generators or whatever medium is used to transfer the heat of the primary to the secondary.

Detectable radiation in the secondary side is a sign of a primary to secondary leak most likey due to something with one or more u-tubes in a/the steam generators. Saying that this is of 'no concern' is complete and utter bs. The chemicals used in the secondary side to treat the water cause sludge to build up in the bottom of the steam generators. This sludge has to be removed regularly and it is removed by doing bottom blow-downs on the steam generators. Bottom blow-downs blow out the sludge from the bottom of the steam generators by letting it blow out to the sea. If you have a primary-to-secondary leak, no matter how small, you are letting Cesium, Krypton, and other highly radioactive particles into the secondary side. These will combine with sludge in the bottom of the steam generators and will eventually be blow out to the sea.

Furthermore, any primary-to-secondary leak, no matter how small, especially with the reactor under power, will produce levels of radiation in the secondary that are very bad for us. Not only do you have gamma emitters but you also have alpha and neutron emitters.

Seeing how they say they are going to replace the core tells me they have identified a leak and are down playing it buy saying it needs a new core. Something tells me that the core isn't going to be the only thing replaced. I also see this as an identified leak by how they covered it up for so long (2 years). This tells me they were monitoring the leak to see if it was getting worse. It appears it was getting worse as they say they are going to replace the core.

In the US Navy the only reason we replace reactor cores is if we are close to being Xenon-precluded on startups (after a scram). After a reactor scram the radioactive byproducts in the core start decaying. The buildup of Xe-135 in the core (a poison) from this decay peaks a certain time after the reactor has scrammed. If the level of this Xe-135 is high enough then no matter how high you pull the rods out of the core the reactor will never go critical on startup. This means you are now Xenon precluded and must wait until the level of Xe-135 in the core decays away to the point where you can pull rods to take the reactor critical. Being Xe-135 precluded is a very bad thing when you are in a situation where you need power now.

Westinghouse and General-Electric reactor cores are good for 20-25 years AT FULL POWER (100%). Almost all vessels that use nuclear power rarely ever run higher than 50-60% Rx power. You can easily get 25-30 years on the core. The only really limiting time-factor on the core is whether you are close to being Xenon precluded on startup after a scram or not.

Can they get the old core out through a hatch?

Highly doubt it. Usually you have to cut a hole in the vessel to extract the core. The amount of safety precautions that have to be in place for this is staggering and another reason why they usually cut a hole for it. Anyone know how many Mega-watts the core is in this sub? I would guess around no more than 150.

I wonder if the UK recycles their spent cores like the US does :hmmm: We have a place in the US (I won't disclose where) that is called the ECF - Expended core facility. We ship almost all the old cores to this place to recycle them - remove the still good fuel from the core and reuse it in new cores.

The thing that always killed me about this ECF place is how they got the cores to the place - by rail. The cores are shipping in what looks like huge big-mac containers on a rail car. If only the citizens of every country new what was going on in their country :shifty:

Yeah sounds like a primary to secondary leak to me too. And yeah, only way to get the Rx out is through a massive hull cut. Meaning a year minimum in drydock, probably two.

Oh and TDW, I like you! But then again I do get along with nucs pretty well.:up:

Considering the way modern subs are constructed, I would think that cutting a huge hole in the hull would degrade the integrity to the point of making it totally unusable. I would be squeamish during every dive afterward.:huh: IIRC isn't that the reason why the USS Enterprise became a museum ship?
Yes, I know that's a ship and not a sub but, they would have needed to cut a big hole in her to remove the pile.

The article quoted in the OP said three years but, that probably covers a complete refit for the entire boat.:)

I was a former Nuke EM but surface ship - CGN 37 USS SoPig. Made E-5 during the 'dark' side of Power School and put on E-6 after 2 years on the boat. Talk about animosity!! Left as an E-6 bucking E-7. Not even the chance to throw on Khaki's could get me to stay! Did my 6 and got the hell out so that I could make some real money in the civilian world :D After 15 years of being a civilian I would never go back. I love being able to tell people NO.

As far as cutting holes in ships it's not a big deal. You should see how they do the welding (heat soaking before and after). Integrity of the hull is maintained.

It's more of a time issue than engineering. To perform the needed hull cut you need to: drydock, make the cut, move what ever equipment in or out, weld the hull section back together, and then back out of drydock. The Ohio class was designed with removable escape trunks to facilitate moving equipment in and out without the need for a hull cut. Turning a 2ft diameter hole into a 6ft one makes life much easier.

More than likely. Since refueling is such a big deal a lot of work will be deferred until it's time to refuel. Then they can combine refueling with a midlife overhaul at the same time saving money and keeping the vessel operational for longer.

I **** you not, every nuc I get along with always ends up being an electrician. :haha: Yeah I can see how that would ruffle some feathers. We always gave the nucs **** about being push-button E-4s and how I earned my crow. But being a nuc is one thing I'm glad I didn't get into, the pay was good but the hours sucked.

Ah HY-80 and HY-100 welding, try and weld that cold and it will laugh at you. Titanium is even worse, I still don't think we know how the Soviets did it. :doh:

HMS Dreadnought is currently being built 3 more to follow

That post from Oberon was made in 2014 :)