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

[hkky]

Getting back to nuclear power if the trend continues, 20 years from now "the West" will simply lose the capacity to build civilian nuclear power plants. Once this happens then it will No longer be by choice.

Secondly...

Currently all new nuclear reactor construction must be at least based on 3rd generation technology. 2nd generation does not meet standard and thus cannot be built. Using this logic, 20 years from now all new construction must be at least based on 4th generation technology. China is the only country that has a 4th generation nuclear reactor currently in operation, the HTR-PM reactor. Therefore they have the lead.

That may be a possibility, but future is very uncertain. The US essentially stopped building new plants (except for a few already under construction) after the Three Mile Island accdient in 1979 and yet there was sufficient combined expertise/infrastructure to build AP1000 30 years later. Given the current trajectory, China will be in a better position on nuclear fission. However, there are bunch of activities in many countries (including China - CNNP may be building world's first modular reactor) to develop smaller reactors which will be easier to build (and maintain capability). As things stand, the US will be operating a sizeable fleet (likely > 40) into 2060s and so expertise will be around, unlike the moon program that fired majority of the expertise as soon as the progrma is over. Several years ago I compiled the chart below (projecting expected number of operating plant in the US based on license expiration and 20 year extension to 60 years), to gauge viability of employment in the US in commercial nuclear fuel research. Plants are now doing another 20 year extension to 80-year life and so the curve will shift to the right.



Not sure of the HTGR as a model reactor to expand into the future. Fuel density is low and so large spent fuel mass have to be dealt with. Some of the new smaller plant designs are also passive safe and they burn out highly active acnides, rendering spent fuel relatively safe after hundreds of years instead of tens of thousands of years.

Who knows what will happen in 20 years. Fussion physics is well understood now and combined with material/super conductor advances I may see a sustained reaction with energy return in my life.

 

[gelgoog]

The US is trying to convince other countries to go all in on buying modular nuclear reactors. Vaporware reactors from shady US private companies which never even built a prototype let alone a working power plant are signing letters of intent all over the place. This is basically naval reactor technology mass produced for the civilian power market.

 

[charles18]

Not sure of the HTGR as a model reactor to expand into the future.

Let's assume the last PWR reactor gets built 20 years from now, with a 60 year operations life. That means the last PWR reactor to be retired will be in 2024 + 20 + 60 == the year 2104. The US navy built a PWR reactor back in 1953 so that means PWR technology will have a 150 year run. That's about the same amount of time steam powered locomotives were used until they were phased out in the US in the 1960's. I think 150 years is "enough". Surely there must be some new technology that will come along to act as a successor.

Fuel density is low and so large spent fuel mass have to be dealt with. Some of the new smaller plant designs are also passive safe and they burn out highly active acnides, rendering spent fuel relatively safe after hundreds of years instead of tens of thousands of years.

You are correct. HTGR technology has some problems that are baked into the cake.
but...
It is still an improvement over PWR with its higher operating temperature and thus thermal efficiency.
Also the process heat can be used for industrial applications which is an added bonus.
As for its low power density that is completely irrelevant if the job is to create a stationary power plant.

The PWR reactor dominated the 20th century simply because the USA was the biggest market so therefore they get to "call the shots" and that was the decision they made.
Which nuclear reactor will dominate the 21st century? I just know that obviously "the West" will Not be in charge of making that decision because China has the largest market.

 

[gelgoog]

I am not that sure about the pebble technology used in the HTGR. The AVR and THTR-300 in Germany had a lot of issues with stuck pebbles, cracked pebbles, and the like when they were operating as experimental designs. The Japanese seem to be developing prismatic HTGR which might be more reliable. But silicon carbide in general has proved finicky to use as a cladding material.

The idea of HTGR and the cycle itself seems promising but the actual materials and ideal geometry are probably still not available.
It will take operation over a long term period to prove if the design is reliable or not.

 

[charles18]

I am not that sure about the pebble technology used in the HTGR. The AVR and THTR-300 in Germany had a lot of issues with stuck pebbles, cracked pebbles, and the like when they were operating as experimental designs. The Japanese seem to be developing prismatic HTGR which might be more reliable. But silicon carbide in general has proved finicky to use as a cladding material.

One of the problems the Germans had was the gas / helium pump used oil as a lubricant for the rotor shaft.

Small amounts of oil would leak out, gum up the pebble balls in the reactor, and contaminate the entire primary cooling system. A contamination, even a small one, carried over for years equals a big problem. Liquid cooled reactors don't have this problem because the lubricant oils would simple just dissolve into the water.
The Chinese created a rotor that was electro magnetically levitated (Maglev). Since there is no physical contact this eliminates the need for lubricant oils and thus the problem was solved.

No more sticky pebble balls!

 

[Stealthflanker]

Things about HTGR and such is.. how would you insulate them ? like given the temperature they're operating, it's gonna be hot as f in reactor room. Particularly that submarine does not have the luxury of volume as land based reactors or surface ship where one can easily put lots of ventilation. Are the reactor room gonna be left unmanned during the entire duration of the cruise ?

The current Submarine PWR reactor is already spouting saturated steam at about 294 degrees celcius. While Russian p.705 "Lyra" or Alfa operates at superheated steam of some 300-400 degrees celcius, thus apparently why the reactor room and basically engine room too was unmanned.

HTGR may reach as high as 1000 degrees celcius or more, especially if one desires brayton cycle engine (Yes a Nuclear gas turbine).

Ideas on novel submarine propulsions like that has been around for decades, yet countries seems to be content atm with current PWR and improvements (integrated steam generator, which first adopted by French). Despite the apparent high energy density of the novel reactors (Liquid metals, HTGR etc) Interests at these reactors seems not appear yet.

 

[MinhHaiNguyen9001]

JL-2 SLBM launch