CV-18 Fujian/003 CATOBAR carrier thread

[snake65]

Submarine reactors are good for about 30,000 HP. A carrier reactor need to be 3-4 times more powerful. The Soviet Navy had far deeper and broader experience with submarine nuclear reactors than the Chinese navy. But even the Soviet navy repeatedly put off designing a true surface ship reactor in order to avoid the risk. The mixed propulsion in the Kirov class semi-nuclear cruiser wasn't adopted out of some inspired compromise as some western commentators have suggested. It was adopted because the Soviets chose not to undertake to design a proper surface ship reactor, and used weak submarine reactors instead, thus necessitating an extra oil fired booster boiler for maximum power.
So for the Chinese it is prudent to use proven conventional propulsion technology with their first CTOBAR carrier in order to minimize possible delays in getting her into service.

Soviet KN-3 reactor on Kirov class cruisers (2 units) and also intended for Ulyanovsk class CVNs (4 units) is a purpose-built surface ship reactor with 300 MW (70000 hp) output. 2 steam boilers on Kirov are just a back-up in case of reactor failure. Admiral Gorshkov did not want his flagships stranded somewhere in the middle of Pacific.
Soviet boat reactor OK-650 has 190 MW (43000 hp) output.

 

[Richard Santos]

Soviet KN-3 reactor on Kirov class cruisers (2 units) and also intended for Ulyanovsk class CVNs (4 units) is a purpose-built surface ship reactor with 300 MW (70000 hp) output. 2 steam boilers on Kirov are just a back-up in case of reactor failure. Admiral Gorshkov did not want his flagships stranded somewhere in the middle of Pacific.
Soviet boat reactor OK-650 has 190 MW (43000 hp) output.

uh, no. 300mw is equal to 40,000 hps. 190 MW is equal to about 26,000 hps. Kirov's 40,000 hp KN-3 reactor were developed from submarine reactors, and are not clean slate surface ship reactor designs. Hence the output range.

The oil fired steam boilers are not just "backups" for the nuclear reactors in the Kirov. The two nuclear reactors in the Kirov can manage only 80,000 hps, enough to drive the ship at about 25 knots. The oil fired boilers have to be brought online to supply the additional steam to the turbines to,achieve the maximum designed speed of 32 knots.

 

[Orthan]

sputnik article about the 002 class. IDK if it has anything new.

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[Twix101]

Seems that I moved a lot of debating about the possibilities in terms of propulsion. I don't pretend to be holding the absolute truth of course.

There are pros and cons choosing a mode of propulsion. Having a conventionnal one mitigates risks in terms of design and construction, and it seems that it is the most likely path that PLAN is choosing for the 002.

Nuclear options offers a wide range of advantages over long term goals. Such ships have greater flexibility in moving from theater to theater, are less dependent on oil supply lines, frees more space for true air operations (more hangar, more aircrafts, more weaponry) and can go at full speed most of the time.

Most debate about definitive design not being frozen yet were about catapult technology. There could be also a debate about wether getting more flexibility for a major surface ship for the incoming 40 years, at least, she is going to be in comission.

 

[Richard Santos]

Indian hasn't got any working naval nuclear reactor .. while China has had it since early 1970 (Han SSN) ... so there is no comparison ... and PLEASE don't bring any India into this discussion or comparison

Yes, they do. Their first domestic submarine reactor reached criticality in 2003, and their domestically built nuclear submarine powered by it had been undergoing sea trail since 2014 and in commission since 2016. Admittedly it is a rather anemic 10,000 hp unit, and even with improvement in power output resulting from further development 8 seem insufficient to power a 60,000 ton carrier to 30+ knots.

 

[Orthan]

Nuclear options offers a wide range of advantages over long term goals. Such ships have greater flexibility in moving from theater to theater, are less dependent on oil supply lines, frees more space for true air operations (more hangar, more aircrafts, more weaponry) and can go at full speed most of the time

Moving from theather to theater and less dependent for oil lines is not very useful to chinese navy because it will basically only operate its carriers in the west pacific. As for the question of space, it depends on how big nuclear reactors are. The US navy ones should be small for sure, but chinese ones? i doubt that china can develop nuclear reactors as small as us navy.

 

[Richard Santos]

The big benefit of nuclear power to carriers is not really strategic mobility from theater to theater so long as the escorts remain fossil fuel powered. The biggest benefit is all the bunkerage space otherwise would be filled with fuel oil for the boilers can now hold jet fuel and thus increase the operational persistence of the carrier.

I would not be surprised if the Liaoning's total fuel capacity for its own engines are well in excess of 5,000 tons. In a nuclear carrier all that can be devoted to aviation fuel.

 

[schenkus]

uh, no. 300mw is equal to 40,000 hps. 190 MW is equal to about 26,000 hps.

I think your numbers are a bit off: it seems that a naval reactor of 150MWt will power a turbine with about 30MW shaft power, which is about 40000hps. (the ratio of ~5:1 thermal to shaft power is worse than the about 3:1 thermal to electric for power stations) (

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[delft]

Moving from theather to theater and less dependent for oil lines is not very useful to chinese navy because it will basically only operate its carriers in the west pacific. As for the question of space, it depends on how big nuclear reactors are. The US navy ones should be small for sure, but chinese ones? i doubt that china can develop nuclear reactors as small as us navy.

If the first nuclear powered flattops starts building in ten years time or later the reactor might be a Thorium Molten Salt one that is considerably smaller than the best Uranium reactor:
* the working temperature is much higher so for the same mechanical power output the thermal power is much smaller, so the rate of splitting U atoms is much lower
* as many neutrons as are needed to maintain the chain reaction are needed to convert Th atoms into U233 atoms, so with an average of about 2.5 neutrons per split U not 1.5 will have to be absorbed by lead shielding but about 0.5.
This makes a thorium reactor much smaller and lighter and might even make it attractive for a successor of 055. It might also make it attractive not to build U reactor powered flattops but in stead a few more oil fuelled ones. The Shanghai flattop builder looking for people to man its nuclear power department suggest otherwise however.

 

[Jura The idiot]

If the first nuclear powered flattops starts building in ten years time or later the reactor might be a Thorium Molten Salt one that is considerably smaller than the best Uranium reactor:
* the working temperature is much higher so for the same mechanical power output the thermal power is much smaller, so the rate of splitting U atoms is much lower
* as many neutrons as are needed to maintain the chain reaction are needed to convert Th atoms into U233 atoms, so with an average of about 2.5 neutrons per split U not 1.5 will have to be absorbed by lead shielding but about 0.5.
This makes a thorium reactor much smaller and lighter and might even make it attractive for a successor of 055. It might also make it attractive not to build U reactor powered flattops but in stead a few more oil fuelled ones. The Shanghai flattop builder looking for people to man its nuclear power department suggest otherwise however.

LOL about two (?) years ago I tried to find info about the new USN reactor, the one which by now is on the Ford (CVN 78), and I didn't even figure if it's U or Pu burning ... I doubt we'll ever know what the Chinese use or don't

by the way I'm still interested in that US reactor ... maybe something was leaked? (no pun intended)