no fusion power Traveller

[Nathan Brazil]

MgT1e, unlike T5, has no specifically stated prohibition against using fission to power Jump Drive. If there is a reference in the ruleset that says otherwise, please post the page reference.

Using the MgT1e High Guard Rules (where fission plants were given an official change compared to the Core Rules):
Fission plants are double the tonnage of fusion drive. Fuel tonnage is the same but provides for 52 weeks operation at MCr1.0 per ton or around Cr.38,462 every two weeks.

Using the RAW, the MgT1e Core Rulebook provided a different result. Essentially a given drive generates 1/2 the rating (round down) so basically the highest Rating a Fission Plant produces is Rating 3 and to even achieve a 1 requires a larger drive. Which means 3G and Jump 3 is the maximum. Fuel tonnage is the same as a fusion plant but provides for 52 weeks operation at MCr1.0 per ton or around Cr.38,462 every two weeks.

In both cases, this means reduced cargo or othere tonnage as your plant chews up more. Also power plant fuel cannot be scooped. This may make economics of operating some existing designs prohibitive to make a profit. But if you fill the tank, the lights are on longer.

Also the limit of 3G Jump-3 whatever it does to an existing universe makes some areas harder to cross or combat changes.

 

[kilemall]

MgT1e, unlike T5, has no specifically stated prohibition against using fission to power Jump Drive. If there is a reference in the ruleset that says otherwise, please post the page reference.

Using the MgT1e High Guard Rules (where fission plants were given an official change compared to the Core Rules):
Fission plants are double the tonnage of fusion drive. Fuel tonnage is the same but provides for 52 weeks operation at MCr1.0 per ton or around Cr.38,462 every two weeks.

Using the RAW, the MgT1e Core Rulebook provided a different result. Essentially a given drive generates 1/2 the rating (round down) so basically the highest Rating a Fission Plant produces is Rating 3 and to even achieve a 1 requires a larger drive. Which means 3G and Jump 3 is the maximum. Fuel tonnage is the same as a fusion plant but provides for 52 weeks operation at MCr1.0 per ton or around Cr.38,462 every two weeks.

In both cases, this means reduced cargo or othere tonnage as your plant chews up more. Also power plant fuel cannot be scooped. This may make economics of operating some existing designs prohibitive to make a profit. But if you fill the tank, the lights are on longer.

Also the limit of 3G Jump-3 whatever it does to an existing universe makes some areas harder to cross or combat changes.

That fueling sounds similar to what I worked out for my CT/HG IMTU, although I had it be for several years, and a lifespan for the power plant due to neutron embrittlement.

Fission power plants of course are a critical damage away from irradiating your whole ship, and getting to zero factor whatever way that happens should mean a complete refueling, in addition to the cost of repair/replacement.

 

[Enoki]

How does a steam plant work without gravity?

Steam will flow as a gas from high pressure to low pressure. If you are running it through a turbine it turns it the same as if it were in gravity. The feedwater side after condensing it would be pressurized and solid water using a pump to move it back to the steam generator.

So, you really don't need gravity for such a system.

 

[Enoki]

It is possible that the collector isn't collecting electricity but some exotic particle.

Ah, of course!

The stuff that makes anything work! :rofl:

 

[aramis]

Therein lies the rub.

Literally why most modern rockets have ullage motors, and Niven had his protagonists start in tidal force.

 

[Orr]

So, you really don't need gravity for such a system.

Moisture separation requires gravity. Even reactor designs which produce superheated steam, and most do not, require moisture separation between turbine stages.

Without moisture separation, the thermal efficiency of such a system takes a huge hit.

 

[Grav_Moped]

Worst case, add a centrifuge stage for moisture separation.

 

[Orr]

Worst case, add a centrifuge stage for moisture separation.

Have any idea how that might work?

 

[Grav_Moped]

Spin the entire turbine housing on its axis, and collect the condensate from the outer edges?

 

[Enoki]

Moisture separation requires gravity. Even reactor designs which produce superheated steam, and most do not, require moisture separation between turbine stages.

Without moisture separation, the thermal efficiency of such a system takes a huge hit.

No it doesn't. Steam is a gas. You keep the condenser at a partial vacuum, making it the low pressure point of the system. As the steam passes across the cooling portion of the condenser, it turns back into a liquid. The pressure being higher coming from the turbine keeps the liquid from flowing in that direction. If you had the condenser using centrifugal force or something in zero gravity it would move the liquid to a specific location for collection.

Now, if you made the steam from something other than water... This would depend on the materials you had available and what they could handle...

Imagine for a second you are using say iron for the steam... (yes, you can boil iron) and the system would work with that. Now you have a magnetic material so collection would be easy.

In any case, you can move a gas simply by pressure differential. Water steam plants do that now. They don't rely on gravity for the steam portion to do it either.
Moving water in a closed pipe system between two points doesn't rely on gravity either. You have a pump moving the water. Any liquid would be the same.
On the liquid side of the plant you can use a pressurizer with a diaphragm to pressurize and solid the liquid side using a gas on the other side to do this.

This is really no different than liquid or gas systems on an aircraft where they have to be capable of working at zero, or even negative gravity.

 

[Orr]

No it doesn't.

Yes it does because every USN reactor installation uses moisture separators as do US civilian power plants be they PWRs or BWRs.

When you "pull" energy out of the steam, you get moisture in it and enough moisture will destroy your turbines.

 

[Condottiere]

Put the turbine in a hamster cage.

 

[Enoki]

Yes it does because every USN reactor installation uses moisture separators as do US civilian power plants be they PWRs or BWRs.

When you "pull" energy out of the steam, you get moisture in it and enough moisture will destroy your turbines.

You can also superheat the steam to the same effect. The reason you use a separator is because the steam is wet (or saturated) and you want to get the moisture left out to have "dry" steam.

Superheating does the same thing. It eliminates the moisture by forcing it to become steam.

Today, few plants run superheated steam because of issues with pressure and temperature, but it has been done in the past and could be used in the future.

 

[Orr]

You can also superheat the steam to the same effect.

Boiling water reactors, like those at Fukushima, produce superheated steam. They still use moisture separators between turbine stages because as it move through the turbine the steam's temperature and pressure eventually drops from the superheated region to below the saturated steam line to become unsaturated or "wet" steam. Superheating doesn't matter because you're pulling energy out of your working fluid which will drop it out of the superheated region and into the unsaturated one.

This link (daily mail, jpg) is a picture of the turbine deck at Nine Mile Point plant in Scriba, NY. To the right of the blue turbine housings, you can see three series of piping, valves, and vertical cylinders. That equipment is part of the moisture separating equipment which "dries" steam exiting one turbine set before it enters the next.

That steam needs to be dried despite the fact it entered the initial turbine set as superheated steam.

Saturated steam produced by conventional boilers still contains about 3% water by volume as water is "mechanically entrained" as it leaves the steam drum and carried along. The steam generators used in pressurized water reactors have integral moisture separators which pass only "dry" steam when water levels correct. Systems using either also require moisture separation between turbine sets and for the same reason.

I used to repair turbines. I now make turbine blades for steam, gas, and aeronautical applications. Damaged and destroyed turbine blades put food on my table. Knowing how blades get damaged helps me help my customers.

 

[Enoki]

Boiling water reactors, like those at Fukushima, produce superheated steam. They still use moisture separators between turbine stages because as it move through the turbine the steam's temperature and pressure eventually drops from the superheated region to below the saturated steam line to become unsaturated or "wet" steam. Superheating doesn't matter because you're pulling energy out of your working fluid which will drop it out of the superheated region and into the unsaturated one.

This link is a picture of the turbine deck at Nine Mile Point plant in Scriba, NY. To the right of the blue turbine housings, you can see three series of piping, valves, and vertical cylinders. That equipment is part of the moisture separating equipment which "dries" steam exiting one turbine set before it enters the next.

That steam needs to be dried despite the fact it entered the initial turbine set as superheated steam.

Saturated steam produced by conventional boilers still contains about 3% water by volume as water is "mechanically entrained" as it leaves the steam drum and carried along. The steam generators used in pressurized water reactors have integral moisture separators which pass only "dry" steam when water levels correct. Systems using either also require moisture separation between turbine sets and for the same reason.

I used to repair turbines. I now make turbine blades for steam, gas, and aeronautical applications. Damaged and destroyed turbine blades put food on my table. Knowing how blades get damaged helps me help my customers.

Boiling water reactors (BWR) use saturated steam. If it were superheated, there would be no water present covering the reactor. The definition of superheated steam is steam without a liquid component. The steam is all gaseous.

TMI used a pressurized water reactor system with steam generators that produced saturated (wet) steam that had to have the moisture separated.

So long as you end up with dry steam (eg., no liquid water in it) you're fine. This just requires the right combination of temperature and pressure to achieve. By having superheated steam, you ensure even as the steam does work (turns the turbine) you will not get it changing state from a gas to a liquid-gas component.

You then cool the steam after it leaves the turbine in a condenser at a vacuum.

In any case, using a tankless pressurized boiler system eliminates any issues with gravity. The big issue is simply having materials that will withstand the heat involved.

And, it should be possible to use such a system in zero-G as was done on the NB-36H

https://en.wikipedia.org/wiki/Convair_NB-36H

https://www.thisdayinaviation.com/tag/convair-nb-36h-nuclear-test-aircraft/

Clearly, such a reactor and system would have to be capable of operating with odd G forces on it as the plane maneuvered, climbed, or dived.

A way around the problem entirely is to use a pressurized primary to heat a liquid that remains all liquid in a closed loop system. The secondary that drives the turbine uses a gas that is heated by the primary and in effect operates similarly to a gas turbine (jet engine) rather than a steam turbine. The gas is simply cooled after use and recirculated. Then you don't even have to worry about phase changes in the mediums the system uses.

 

[infojunky]

What would a setting without fusion power look like? No sustained, useful /economically viable fusion reactions outside stars.

Honestly a lot like 2300AD.

 

[McPerth]

Honestly a lot like 2300AD.

In 2300AD fusion power exists, and it's even common, but not for spaceships (except the larger ones), as the fusion plants are quite massive.

 

[infojunky]

In 2300AD fusion power exists, and it's even common, but not for spaceships (except the larger ones), as the fusion plants are quite massive.

And? Your point is?

Meaning there will be some sort of large scale power generation, but the smaller local choices will look a lot like 2300AD's.

 

[mike wightman]

And what will T2300 look like by the 57th century?

TNE FF&S gives us the TL progression for stutterwarp, so even if fusion power is never realised you will still have:
cheap space interface using beanstalks, spaceplanes and reusable chemical rockets
stutterwarp for zipping around the solar system and off to distant worlds, with a much increased range from the 7.7ly of T2300
space industry on a massive scale
communication still limited to the speed of ship.

 

[McPerth]

And? Your point is?

Meaning there will be some sort of large scale power generation, but the smaller local choices will look a lot like 2300AD's.

The main difference (setting aside) among Traveller and 2300AD is not as much the widespread of fusion power (after all 2300AD is at about TL 12, so you can expect it to increase with time), but the lack of gravitics.

Yes, if you limit fusion to the larger ships and ground facilities, it comes close to 2300AD (while if you fully take it out, it woun't), but inteface keeps the same problems due to lack of gravitics.

OTOH, in 2300AD this same non widespread fusion power makes its use more limited. Lasers are 1-2 Mw in power, not the 250 Mw ones in Traveller, and the total ship's PP output uses to be in the range of few Mw (10 Mw it's quite a lot in 2300AD), not in the Gw (or even Tw) that Traveller uses to have.