Nuclear welding

[meltedEng]

Hello,

What's the current authoritative and modern references for nuclear welding and fillers, best practices etc? I do not mean applicable codes.

Thanks

 

[kingnero]

Best practices are same as elsewhere. Try to deliver better than average quality for a lower than average price (too bad I can't say top notch work is standard, because it isn't. It's even far, far from common). No tech spec can improve quality. It starts on the drawing board and the shopfloor.

Apart from more stringent requirements (eg. NDT), nuclear welding is much overrated.
Having a good, thorough understanding of what you're doing is paramount. Filler selection will be least of your worries.

 

The materials are almost all identical to those used in the rest of the world.
Nuclear construction codes (ASME) add some testing and property requirements that address considerations unique to nuclear. Also it has some unique degradation mechanisms in the RPV and RPV nozzles that have pushed alloy development and welding techniques.
Otherwise, steel is steel and welding is welding. If you can weld in the civilian world you can weld in nuclear; it's just that the work environment poses some serious challenges.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

The documentation is often the biggest issue as the welding technology is no different.
Mapping who made which welds when with filler lot numbers attached can be a lot of detail to manage.
There have probably been more changes in the NDT methods than the welding.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[bobjustbob]

In the production of valve bodies we had no difference in our weld procedures or process for standard parts and parts for nuclear service. The control of the weld filler and the record keeping for the parts and weld repairs are more stringent than a standard valve component but that is all covered in the code. Our goal was to put in a good weld in all of our parts.

Bob

 

In the production of valve bodies we had no difference in our weld procedures or process for standard parts and parts for nuclear service.

But the folks writing nuclear tech specs will often arbitrarily makes requirements more stringent. This helps justify their existence and emphasizes their superior technical intellect; it is known as 'nuclearizing'. The far higher price they happily pay is actually a validation of their 'superior' engineering.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[bobjustbob]

In some cases I would agree. But this is true in all specialties. Our nuclear parts themselves were not any more challenging to produce than our commercial valves, in some cases easier as the materials were basic WCC/WCB and CF8M for the most part. Our requirements were predominantly right out of the code and well understood. I would much rather deal with this type of order than some of the PED, NORSOK or, heaven forbid, IBR requirements.

Bob

 

[meltedEng]

Ironic, thank you for acknowledging there is in fact a difference in nuclear service welding, appreciate you dropping in, hoped you would. I agree with your comments as usual.

But as you alluded to, we don't have those challenges of field welding, so no in-situ robotics/human risk, just shop fabrication of the RPV and internal intermediate chamber/reflector, and main HX for a low temp reactor.

I am looking for most current references (texts and papers) to reference filler restrictions, whatever is industry standard references as of late, or even relevant papers on plate restrictions on residuals to learn more. Any texts regarding metallurgy in high fluence areas is appreciated.

 

For irradiation damage I would jut google with the terms 'radiation, PWR, RPV, embrittlement, low alloy steel'. This problem has been known for a very long time, but researchers are still learning about precise mechanism on the atomic and nano scales.

bobjustbob,
you are right about where stringent specifications are found: Oil & Gas specs in particular impose some severe composition restrictions and testing requirements, which is understandable in the nasty corrosive and high temperature environments found there. Nuclear for the most part is pretty straightforward once you get away from the reactor and steam generator area; the bulk of a nuclear plant on the secondary side is conventional steam plant.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[r6155]

Welding 600 mm thick and tensioning a 220 mm diameter stud is not an everyday thing. It's quite a challenge.
It's a very nice job.

Regards

 

[meltedEng]

I agree, that's my current course. With 100 texts returning, a bit hard to pick. We've got a short list to purchase today. Always nice to have recommendations though.