09V/09VI (095/096) Nuclear Submarine Thread

[PikeCowboy]

... experience isnt linear like that... europe built more solar panels than china before china caught up. Same with trains, same with with destroyers, container ships, monitors... lol rockets, satellites... fighters, tanks...

Before china had the asbm the US technically had built more asbms than china...

if China built 500 sturgeon equivalents today that doesnt somehow teach it anything new... well it might but probably not as well as if it built 2-3 095s

you dont have to build an equal number of a product In order to catch up technically... and the 10-20 year thing is random

 

[ougoah]

It was an evolution/improvement over time .
They operate with this strategies now.

To go for several years long cycle the fuel assemblies has to validated for that burnup, it needs burnable poisons .
Most importantly it needs experience and validation.

Like the aircraft engine validations for transatlantic flights.





CCCP/Russia and USA designed/manufactured/operated close to 300 nuclear submarines EACH.

China up to this date built 18 nuclear submarines, two third of them been built in the past 15 years.

Do you seriously think that the experience and capability of the Chinese comparable to the USA/Russian ?

It will take at least 50 more submarine and 15-20 years to see really capable nuclear submarines from China.

While there is usually some substance to this sort of argument, in this case, it is ridiculously silly. China has not produced anywhere near as many UAVs compared to the US before the 2010s. Now the tech is comparable if not with China leading in some ways e.g. GJ-11 in service whereas X-47 relegated to a refueling role, and WZ-8 for a modern D-21 recon drone. There are publicly shown equivalents in every sector of UAVs and of course the fall back argument is meh made in China lol. The intelligence disintegrates at this point.

How did China manage to do the above without having to go through decades of catch up and building hundreds of each step along the way?

If this reasoning is true, how come a similar feat is being accomplished in semiconductor fabrication? There are plenty of examples that apply to other countries as well. The best one is already mentioned. China never had experience making railroads and trains but without decades of perpetual lagging and without needing to build every piece of technology as it evolves, China is a global leader. The Japanese did exactly this as well. While the Europeans had railroads and generations of different locomotives, Japan was a ricefield with no clue how a train works and all of a sudden they come out with a superior TGV network and train lol.

A country that has never developed and manufactured monitors before DOES NOT need to start with building millions of cathode ray tubes before they're allowed to build LCDs, Plasma screens, and then OLEDs. That's not actually how technology works at all. It's a common misconception and common because it seems intuitive and there is some truth to it but not where you think it is!

 

[hkky]

To go for several years long cycle the fuel assemblies has to validated for that burnup, it needs burnable poisons .
Most importantly it needs experience and validation.

Nuclear fuel is licensed to burnup limits, most of the countries have a limit similar to the US, like 62 GWD/MTU (Gigawatt-day/metric-ton-uranium) rod average (I think China has an assembly average burnup limit similar to the US rod limit). Couple European countries have no limit and they have to justify every core design for every cycle. But by operating within a licensed limit, the fuel can be burned in different ways a utility chooses as long as they design the core using licensed methodology and safety limits. How long you operate a cycle is then a commercial decision and plant configuration. The difficulty is to be able to load enough energy upfront and maintain control of the reactivity throughout the cycle. China has both gadolinium and boron burnable poison technologies and can design cores to operate 2-year cycles if they want. It comes to need and cost. High energy density cores (most of China's PWR are of high energy density) naturally have to load more U235, have low thermal margin, and thus is more difficult to design for long cycles, but if you want to it can be done by simply load more fresh fuel assemblies each cycle. By doing this you lost the economics. Low energy density cores do operate 24-months cycles. The industry is pursuing enrichment increase of U-235 > 5% and burnup limit increase to 75 GWd/MTU rod average. If regulators approve then even longer cycles may be possible economically. It is major step changes like these or new technologies that require demonstrations and verification.

 

[ougoah]

Nuclear fuel is licensed to burnup limits, most of the countries have a limit similar to the US, like 62 GWD/MTU (Gigawatt-day/metric-ton-uranium) rod average (I think China has an assembly average burnup limit similar to the US rod limit). Couple European countries have no limit and they have to justify every core design for every cycle. But by operating within a licensed limit, the fuel can be burned in different ways a utility chooses as long as they design the core using licensed methodology and safety limits. How long you operate a cycle is then a commercial decision and plant configuration. The difficulty is to be able to load enough energy upfront and maintain control of the reactivity throughout the cycle. China has both gadolinium and boron burnable poison technologies and can design cores to operate 2-year cycles if they want. It comes to need and cost. High energy density cores (most of China's PWR are of high energy density) naturally have to load more U235, have low thermal margin, and thus is more difficult to design for long cycles, but if you want to it can be done by simply load more fresh fuel assemblies each cycle. By doing this you lost the economics. Low energy density cores do operate 24-months cycles. The industry is pursuing enrichment increase of U-235 > 5% and burnup limit increase to 75 GWd/MTU rod average. If regulators approve then even longer cycles may be possible economically. It is major step changes like these or new technologies that require demonstrations and verification.

Is this derived from commercial energy generation? When has there been any disclosed information on Chinese PWRs?

 

[hkky]

Is this derived from commercial energy generation? When has there been any disclosed information on Chinese PWRs?

They are commercial reactors, purchases are of public record, you just need to look for them. Original licensing basis and operating envelope came with the purchases. That's what's great about license actions, especially those in the US, they are public record. China is also involved with IAEA and recently OECD Nuclear Energy Agency activities (these organizations publish information). An example articles,

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, talks about their 18-month core management (essentially core design with economics in mind) development. They are using French fuel design in the paper. CGNPS is qualifying their own fuel design, but I think it got tangled up in China internal politics.

 

[Anlsvrthng]

Nuclear fuel is licensed to burnup limits, most of the countries have a limit similar to the US, like 62 GWD/MTU (Gigawatt-day/metric-ton-uranium) rod average (I think China has an assembly average burnup limit similar to the US rod limit).

Exactly what you argue about ?

The increased fuel cycle/higher burnup is not just dreamed up with the first reactors, but the result of accumulated experience regards of the behaviour of the fuel and the models about the configuration of core.

But the PDF that you linked saying the same :

18 month fuel cycle in GNPS Started in the end of 1998, GNPS 18 month fuel cycle project was implemented to improve the plant capacity. After three years engineering verification and site modifications, the new fuel management has been successfully introduced at 2002, in cycle 9 of GNPS unit 2. At present the plant capacity factor is above 90% normally. With the AREVA’s new generation of AFA fuel assembly AFA3G, the equilibrium cycle length could reach 500 EFPDs with reload batch size by 72. The most important characteristics of AFA3G fuel are M5 cladding and Mid-SpanMixing-Grids. The licensed burnup limit of AFA3G is 52000MWD/tU. And the fuel enrichment is 4.45%

It took 5 years to develop the fuel, and after that they started the trial of it in one reactor.
So we can say that the 18 month cycle fuel required at least 7 years of development + validation, IF they was lucky and the design didn't needed any modification and new trial .

 

[Anlsvrthng]

you dont have to build an equal number of a product In order to catch up technically... and the 10-20 year thing is random

Agree, 50-70 will be enough, don't need to be 300 .

Validation of a non-refuelled submarine core requiring 7.5 years at least. So, 4 evolutionary design cycle takes 30 years.

USA/Russia needed way more time, so it is again accelerated design cycle.

 

[hkky]

So we can say that the 18 month cycle fuel required at least 7 years of development + validation, IF they was lucky and the design didn't needed any modification and new trial .

The contention is cycle length is not a technology bottleneck for China, it is economics that has the most impact on what cycle length to use, "With plant upgrades, advanced fuel management has been introduced into the two plants to improve the plant economical behavior with the high burnup fuel implemented.". To use longer cycle length, you have to make sure all of your critical equipment can operate that long without maintenance and thus some components and maintenance schedule upgrades may be necessary. For some plants this may be merely a review of the components spec.

China was using Zircaloy-4 cladding material, but later bought the M5 cladding material with AFA3G fuel design. They did not spend 5 years to develop the fuel. To transition to a different cycle length (to reach equilibrium cycle) requires several cycles, likely 3, because they remove at most 1/3 of the fuel each cycle (in one of their other core designs, they replace 1/4 of the fuel). The paper stated a licensed burnup limit of 52 GWd/MTU for the AFA3G design, this is batch burnup limit as indicated in Table 1. Batch limit is the average of the entire reload (1/3 or 1/4 of the core). Due to power variations between assemblies and within each assembly the peak rod burnup would be likely be 20% higher, which would be similar to the US peak rod limit of 62 GWd/MTU. So the cycle length choices are constrained by similar factors as most of the other countries.

They could have also designed longer cycle cores with Zircaloy-4, but they'd have to feed in more fresh fuel because Zircaloy-4 may or may not be licensed to the the same burnup limit, which makes it not economical.

There are lots of literature material out there you can read.

 

[Orthan]

Agree, 50-70 will be enough, don't need to be 300

You must know more than me, but AFAIK the UK has only built about 29 nuclear submarines to this day. I dont think that they are behind the US in terms of nuclear submarine tech.

 

[Anlsvrthng]

The contention is cycle length is not a technology bottleneck for China, it is economics that has the most impact on what cycle length to use, "With plant upgrades, advanced fuel management has been introduced into the two plants to improve the plant economical behavior with the high burnup fuel implemented.". To use longer cycle length, you have to make sure all of your critical equipment can operate that long without maintenance and thus some components and maintenance schedule upgrades may be necessary. For some plants this may be merely a review of the components spec.

Still hard to see that you argue about.

So, the reason why the Los Angeles class needs midlife refuelling is because the US navy decided it is cheaper than if they have full lifetime cores ?

Or because there wasn't validated fuel for this long operation ?

Same for civilian, the capacity factor improved over time, more knowledge accumulated about the behaviour of fuel in the reactors, it lead longer cycle / higher burnup.

C'mon, a simple aircraft break pad has higher validation requirement than your nuclear fuel validation model. : )