Cost of reactor refueling?
 

I once read a article that was claiming that the cost of refeuling a SSN688 was 250-500 million dollars. :-? :dead: Why would it cost that much? That's almost half the cost of the original boat! Has anyone else heard of similar prices?

Astute has a core that will not need refuelling during the life of the boat.

One million dollars.

http://arbyte.us/blog_archive/2005/1...on_dollars.jpg

Seriously, I don't know.

Here is a long winded partial explaination. I have never done one myself, but I knew people who did do one and the things they would tell you.. It makes you shudder.

Well, here is a simple breakdown.

When you refuel a reactor you have to basically cut the boat open to access the top of the reactor vessel. This is not an easy job to begin with as you have a LOT of metal you have to remove VERY carefully as you have to be able to put it back together and go back to sea. This is a ships structure and is not designed for removal. It is designed to keep water out the the people tank. You have to be careful as you can not just run down and find another piece of hull if you should happen to damage or (god forbid) lose a piece.

Now that you have it open, you have to establish and MAINTAIN a clean room enviroment to work in. You do NOT want to have any foreign materials fall into the reactor vessel as there are many many many bad things that can happen if something should compromise the hydrodynamic conditons of the plant. Something as small as a 1/2" nut could make you have to tear the whole thing apart again to locate a problem. Maintaining the clean room enviroment if a 24/7 thing normally maintained by the ships crew (aka engineering department). The caveat to this is that normally, by the time re-fueling comes around, the actual reactor compartment is too 'hot' for continous manning. So you have to have controlled access and remote monitoring.

A lot of the money is the materials (uranium oxide ain't cheap you know) that the core is constructed of. You also have all the related costs of accurately assembling the core prior to installing it into the reactor vessel. This is incredibly detailed work as EVERYTHING has to be done right the FIRST time. This kind of precision is not cheap on manpower.

Then you have the dissasembly, transport, and storage of the spent fuel assembles. This is not commercial power plant grade fuel, this stuff is highly enriched. You have to give it some decay time before you can take it apart for recycling. This cost too is factored into the re-fueling.

So now you have opened the hull, established the proper conditions, removed the core, and then installed the new one. You close the actual reactor vessel up and guess what? Now you have WEEKS of testing.. (all of it non-power ops) making sure that the plant has the proper integrity and that everything is at should be. You do all kinds of crazy testing to make sure that the plant is within operating specs. This is all done with the hull of the boat still open. They do not close up till they are sure you do not have to go back into the reactor vessel. This means you still have to maintain the cleanroom environment while this is going on.

You have to factor the cost of the shipyard time (That drydock is NOT free) as you are in there for MONTHS. They do not just refuel the core, the do a comprehensive overhaul and upgrade of the boat to bring it up to current fleet standards. There is ALWAYS a Shipalt or two requires you to be out of the water to do. They also do other hard patches (removal of a section of the hull) to get at large bulky items. Hey, if you are going to de-certify a ship for sea, you might as well do it BIG time and get your moneys worth out of the re-certification process.

Now... You have to put this sucker back together. You have to make sure that you can go down to test depth safely. This means getting the sub re-certed as Sub-Safe (american boats). This means that ALL that metal you took off the hull has to go back into the EXACT position it was in whe the boat first came out of the water. This sounds a WHOLE lot easier than it is. (I have done a hard patch once. It was not fun)

Ok, now you have the hull in one peice. It is time to break out the NDT inspection machines and, in minute detail, check EVERY weld that was done on the pressure hull. Absolutely NO flaws are allowed. They even THINK there is a problem they grind and redo it.

So now you are in one piece.. and they stick you back in the water. Guess what? Thats right! MORE testing. All of it now in power ops. You bring the core on-line and you have to verify all the characteristics of the new core. This is weeks of work again.

Then you have sea trials where you actually go out and play with all your new toys and do yet MORE testing. All this testing is down every step of the way with the shipyard engineers who do not do this for free.

At the end of all this you have basically a newish boat for less than half the price of a brand spanking new one.

One thing to consider here, it is not much more expensive that the ORIGINAL core was in the first place. A reactor plant is NOT cheap to shart with.

What if, by that time (25-30 years ?) budgetary constraints prevent timely replacement of the sub ? I know 25 years is a long time, but given the tendency of high-tech weapons to ever increase in price... The UK government then could decide to keep the hull and extend its life.
Probability of such a scenario looks remote, but who knows.

On the subject of core replacement, the future Barracuda SSNs are going to use commercial-grade fuel. While it's cheaper, it means the core will have to be replaced during the planned life of the boat. I absolutely don't know if the costs balance :cool:

That was a freakin' great post Bubblehead. Thanks.

PD

If that's the case, then why not swap out the entire reactor vessel. Open the pressure hull, disconnect the piping from the reactor vessel to lift the entire thing out, and pop in a brand new reactor vessel that had already been precertified by the shore guys and is ready for install just like swapping out a battery. Seems like it would be easier.

Thanks for the insight.

See in the infinite wisdom :roll: of the designers of the 688 class submarines there are no hard patches on the boat (ie areas of the hull designed to be removed to faclitate the instalation of new equipment.) The entire stern of the boat needs to be dissassembled as per Bubblehead Nuke's post to swap out any componet bigger than the hatches of the sub and then rebuilt. Older boats Sturgeons etc had these hard patches that could be cut out and welded back in place when an upgrade was complete.

This would be a major undertaking what would basically require cutting the boat in half as the reactor vessel, being the single most massive piece of the ship, is WELDED to and is part of the structure of the ship. If there is one thing on board that you do NOT want to have move, it is the reactor vessel and the primary coolant system piping.

This is why they have the closure head in the first place.

Oh, and as for swapping out a battery. That is a good solid 3 week job in shift work to accomplish that. This is with shipyard support. We pulled a perfectly good battery out of my boat to put a short Ohio class battery in a 688 for the purposes of NavSea testing. The differnces were remarkable. Instead of being worried about battery life from the moment the reactor scram'd, we could litterally run the boat off the battery and the SSMG's for about an hour before we really started getting worried. To those older 688 sailors, it was more than a doubling of the amperage available for the same size battery. We had to reballast the whole boat due to increase of weight.

688's were designed to be quick so they were therefore light.The downside of this was it restricted their diving depth and caused problems with refuels.Many compartively young boats have been retired when they became due for a refuel.
The design process of the 688 is covered in Running Critical by Patrick Tyler.

ugh.:dead: Those service requirements are depressing. No wonder most new designs are going with a 30 year core...

I don’t suppose you can tell the stories you’ve heard? The back half of nuclear submarines has always fascinated me, even when I was a little kid. Unfortunately, being tall (6’9”) meant I wasn’t eligible for submarine duty.

Of course it the one area that’s considered a guarded secret, and no member of the press as been allowed or any pictures have been taken aft of the entrance to the shielded tunnel thru the reactor compartment. Because of that, I understand if you can’t talk about it much.

As far as the refueling/re-coring process goes, I imagine it’s not all that different than your typical commercial plant after the hull has been opened up. I once had a former submarine nuke tell me that after going to the commercial sector the biggest shock to him was the allowable radiation dosage and contamination during refueling. He said it was almost enough to make him faint when he found out!

There are some great pictures available over at Nuclear Tourist and Nuke Worker of the refueling process for those that are interested.

Another reason for the shocking numbers is that there is much, much more that happens while laid up in the shipyard than the refueling itself. The entire boat is pretty much disassembled, put up into workshops in the shipyard, inspected, cleaned, repaired if need be, and then reassembled back on board. It's like rebuilding the ship over again.

If we're going to spend two years in a shipyard we may as well make use of the time, eh?