Fission in Traveller, or where are my PowerCells?

[ThunderChilde]

In MGT fission is twice the mass of fusion. All tech miniaturizes over time even weapon bays. At TL15 fusion plants drop to 75% size. It seems to me that a mature fission tech, being a TL 6 or 7 technology should have gone through a number of refinements as all the other techs do. Traveller seems to be biased against fission.:nonono:

I am a fan of H. Beam Piper's Sci-Fi. Where are my powercells? BSD is analogous to Collapsium, Abbot lift and drive is akin to cg and thruster tech.

for the OTU all it would take is a few Daryen wild haired researchers to read a paper coming from a genius on Atomic Dorriana to get the ball rolling.:smirk:

 

[far-trader]

A blanket TL reduction ignores the very real minimum limits of most technology though. It's not terribly realistic. Fission reactors fall into this so that might be why they didn't apply it to them. Or Fusion reactors would simply be so much cheaper and smaller and efficient that Fission is pointless as a continuing technology.

For a real simple example take a TL1 Club. It will be the same at TL8 and TL15 and TL21. There's only one way a Club will work and it will be pretty much the same no matter how much the TL creating it advances. Reducing it's weight/mass won't help. Making it out of sturdier materials will only raise the price (but it will presumably last longer). Putting fancy electronics in it may be cool (record your hit force and swing arc to improve your skill through review) but it won't make it any more efficient. And such like.

But nothing says you couldn't do it yourself

 

[aramis]

Uh, hate to sound negative, but clubs HAVE come a long way.

The TL1 club is the TL4 sword or the TL4 baton.

The TL8 "club" is the baton, and uses advanced materials, and more dense weight, so that energy is delivered over a narrower area with more percussive force to the victim, and less vibrational injury to the wielder. (Polycarbonate and steel composite clubs are F'ing viscious.)

 

[epicenter00]

Traveller seems to be biased against fission.:nonono

You're certainly right.

1) "Cheap, plentiful fusion power" is the meme of Traveller technology. Fusion power has always been the "nerdgasm" technology in sci-fi ("It runs on a glass of water!").

2) Fusion doesn't have the "taint" of Three Mile Island or Chernobyl that fission has. Fusion is seen as not producing all those headaches like meltdowns (which is almost entirely due to politics and corporate lobbies pushing inherently less safe reactor designs over safer ones) nor the less-than-sexy prospect of all those barrels of nuclear waste that, for all intents and purposes, will be hazardous forever.

3) Plus, despite all the time and money used on fusion research so far, there still doesn't exist a fusion reactor that puts out even a fraction of the power promised by its supporters. Being one of the ultimate pie in the sky technologies "once it gets working" authors are sort of free to almost make the sky the limit on how good (and how compact) fusion reactors can get.

4) Amongst proponents of "nuclear" power, there's an assumption that fusion is a lineal evolution of fission power. That is, once fusion gets working, there is no application that fusion won't be able to do better and fission will go the way of the dinosaurs. It's sort of like burning wood for power as opposed to burning coal - nobody who can help it is going to make a wood-fired power plant now that we have coal technology.

I'm rather anti-fusion myself, mostly because of reading threads on various Traveller fan boards where fusion power is basically a replacement for thinking up real "futuristic" tech developments ("you know, this horse and plow thing isn't plowing these huge fields fast enough..." "How about a tilling machine?" "A what? No. The solution is a fusion-powered horse!" "Yeah, a fusion powered horse!").

While I'm not a big fan of fission power myself, there's certainly plenty of more refinement that could be done with fission power - I think MGT writers have unconsciously got caught up in the fusion power meme and just sort of threw in fission as that dinosaur technology that some backwards groups use. The way that fusion power is often projected, fission doesn't have much place, but that doesn't necessarily have to be the case - you just have to put "holes" in fusion technology and find a use where fission might work better. Perhaps fission reactors can be more compact for the power produced than fusion (radiation shielding might be easier to handle than heat insulation so fusion reactors might have a bottom end of something the size of a small truck - by the time superior thermal shielding is developed, they're abandoning fusion for anti-matter).

For instance, IMTU, all currently functioning Ancients devices are fission powered. Essentially, fusion power and anti-matter is too volatile and requires too much maintenance (there are devices of these sorts that would work if fuelled but they've long since ran out of fuel). However, the Ancients perfected fission power to a high degree, making it quite safe and able to deliver a consistent amount of power over very long periods of time (thousands of years) using isotopes with very long half-lives. The fission reactors don't produce enormous amounts of power, but for the Ancients, they found a "niche" for it which meant they continued to research it - low-to-medium power applications that would require a constant and largely unchanging amount of power spread over long periods of time in a hassle-free form.

 

[far-trader]

As for making fission viable (filling a hole) something I did (around MT rules I think, maybe TNE) was make the fuel consumption the scale tipper. Sure fusion is volume efficient and cheap, but it drinks down LH2 like water so you've always got to be filling up the huge tank. While (in MTU) fusion was extremely fuel efficient (recycling spent fuel etc) so your "tank" of fusion fuel was good for a year or more*. I made it cost a little more to buy, and required special disposal too, but still the way I had it worked out there were applications where it beat fusion.

* after a year the power output starts to drop as the fuel is less and less recycled

 

[Peter Schutze]

One of the things I liked about tech etc in the Honor Harrington series is that the Graysons kept working on fission when everyone else went fusion and made it competitive again for some applications.

My understanding of the real world technologies leads me to believe fission reactors can have a much lower minimum and maximum output limit than fusion is ever likely to have and are much more 'tunable'. Fusion reactors will consume a decent proportion of their fuel regardless of output, just for containment etc.

So if your travellers want something small (in megawatts) that can run for a couple of years off the one fuel supply and doesnt have to provide at least X Megawatts continuously ..... use a fission reactor. If you want raw power with a high base load output ..... use a fusion reactor with maybe a pair of fissions for emergency/ backups.

 

[The Oz]

Fission in Traveller

Here's some stuff on TRAVELLER fission plants I came up with a long time ago, integrating the nuclear fission plants from MT into HG, with some stuff borrowed from FF&S as well.


Suggested tables for using nuclear fission powerplants in HIGH GUARD, with TL improvements.

Fission Power Plant Table (percentage/factor-based)

Percent	--------TL---------
times	7-9	10-12	13+
Pn	10%	 6%	 3%

Cost is MCr1.35/dton. Fuel for 1 year of continuous full-power operation (good for 10 years of normal operation) costs 1MCr per EP produced. Fuel volume is included in the powerplant volume.

Fission Power Plant Table (EP-based)

TL	dtons/EP	Cost/EP (MCr)
7-9	10		13.5
10-12	 6		8.1
13+	 3		4.05

Fuel for 1 year of continuous full-power operation (good for 10 years of normal operation) costs 1MCr per EP produced. Fuel volume is included in the powerplant volume.

I have also created a Book 2 table for fission power plants. I based this on my TL13+ fission plant values.

Rating	Mass	Cost	Fuel Cost
A	12	16	2
B	24	32	4
C	36	48	6
D	48	64	8
E	60	80	10
F	72	96	12
G	84	112	14
H	96	128	16
J	108	144	18
K	120	160	20
L	132	176	22
M	144	192	24
N	156	208	26
P	168	224	28
Q	180	240	30
R	192	256	32
S	204	272	34
T	216	288	36
U	228	304	38
V	240	320	40
W	252	336	42/50
X	264	352	44/60
Y	276	368	46/80
Z	288	384	48/120

The costs are in MCr. Fuel cost is also equal to the EPs generated (for HG purposes). The values after the slash for the W+ plants is the EPs they must generate based on their performance.

A civilian-fuel reactor running a starship which didn't need full power all the time would last much longer, at least for years instead of months.

Let's do some math:

We assume the core will last 1 year at continuous full-power operation, or 8760 hours of full-power.

The ship needs full power when in flight to/from destinations, and for one hour prior to jump to charge jump capacitors.

While in hyperspace, the ship need 10% of max power to maintain the jump field, ship functions, life support, etc. I have no idea if this is reasonable or not; does anyone else have any idea?

While downworld, the ship needs no power (connected to a dirtside powergrid).

From the Book 2 tables, flight time for a 1-G ship to/from a size A world is 7 hours, add one hour for jump and you get 8 hours. Using that figure to give us some cushion built-in (certainly not all planets are size-A, and you don't need the 1 hour of full power to exit jumpspace) and assuming 30 jumps a year, we need 480 hours of full-power operations a year (remember, it's 8 hours out to jump and 8 hours in from jump, for 16 hours/jump).

30 jumps a year means 30 x 168 hours (average) in jumpspace, which at 10% of full power is the equivalent of 504 more hours of full-power operation.

Total: 984 hours a year of full-power equivalent needed, which means that 8760 hours of full-power on the core will last 8.9 years.

That's how I got my figure of 10 years duration for normal operation of a civilian starship fission powerplant. I figured there was enough slack in my calculation to allow a "rough" estimate of 10 years. Military ships might get only half that, as I would expect them to spend more time in space and less on the ground, plus expending more energy on things like weapons and screens.

The one thing this doesn't account for is the need for LH2 as "fuel" for jump, either as coolant, displacement mass, or whatever buzzwords you want/use.

 

[ThunderChilde]

Here we are at TL7-8 and the current state of the art reactor technologies are the pebble bed types. Safe, clean, efficient and very small. Inherantly impossible to melt down, low shielding requirements. The pilot plants are very elegantly small, granted the outputs aren't stunning, but the are small.

H.Beam Piper's universe was a fission universe, many of the golden age's authors also used fission. I had considered the scale issue before in another thread. I pitched the idea that Fusion only got so small, and that Fission above a certain output level began to out mass Fusion.

 

[aramis]

H.Beam Piper's universe was a fission universe, many of the golden age's authors also used fission. I had considered the scale issue before in another thread. I pitched the idea that Fusion only got so small, and that Fission above a certain output level began to out mass Fusion.

And then of course we have the starkly astonishing allotropic iron power piles of E.E. 'Doc' Smith..

 

[Drakon]

In MGT fission is twice the mass of fusion. All tech miniaturizes over time even weapon bays. At TL15 fusion plants drop to 75% size. It seems to me that a mature fission tech, being a TL 6 or 7 technology should have gone through a number of refinements as all the other techs do. Traveller seems to be biased against fission.:nonono:

Well, lets face it, once fusion technology comes on line, who is going to want the expense, legal hassel, radioactive waste disposition, and other inherent problems associated with fission? There are some very real world reasons why fission would die away. Fusion utilizes cleaner, more abundant fuel, and cleaner exhaust, and far higher energy output, compared to fission. While I am sure it will bring its own problems, from this vantage, it looks to be miniscule compared to the headaches fission presents in this day and age.

 

[Drakon]

2) Fusion doesn't have the "taint" of Three Mile Island or Chernobyl that fission has. Fusion is seen as not producing all those headaches like meltdowns (which is almost entirely due to politics and corporate lobbies pushing inherently less safe reactor designs over safer ones) nor the less-than-sexy prospect of all those barrels of nuclear waste that, for all intents and purposes, will be hazardous forever.

Nobody pushed an unsafe design. If anything the central failure at TMI was they were trying to be too safe, and had too many indications and too much information, too many alarms.

Now Chernobyl, it was an unsafe design, but I don't think you can attribute that to greed, or an attempt to actually be unsafe. The basic reactor design was unstable at low power. The idea was that one would spend limited time in that region. That got forgotten over time, and when they were doing some kind of testing in that power region, nobody remembered the original design problem.

This is how hind sight gets purchased. Nobody intended to be unsafe. Mostly because the liability insurance is a nightmare as it is.

No, fusion does not look to have the same problems. In fission, you have all the energy consentrated in a single lump. That means there is no way to safely and quickly remove or dissapate that energy. And as you note, it is a toxic pollutant that we really do not know what to do with.

With fusion, should something cause a problem, you cut the fuel supply and the thing shuts down. Meltdowns are impossible, because there is a constant fuel flow that can be easily interrupted. Even if it did explode and destroy the reactor, neither the fuel nor the exhaust are toxic, nor highly radioactive, and reactor size, (much like the club example) governs energy output. This is a naturally physical limitation to how large a catastrophic explosion would be.

3) Plus, despite all the time and money used on fusion research so far, there still doesn't exist a fusion reactor that puts out even a fraction of the power promised by its supporters. Being one of the ultimate pie in the sky technologies "once it gets working" authors are sort of free to almost make the sky the limit on how good (and how compact) fusion reactors can get.

The technical challenges have proven to be a bit more than expected, but there does not appear to be any reason to think it won't work, or they can't be solved.

We've gotten the H bomb, we just gotta slow it down a bit.

4) Amongst proponents of "nuclear" power, there's an assumption that fusion is a lineal evolution of fission power. That is, once fusion gets working, there is no application that fusion won't be able to do better and fission will go the way of the dinosaurs. It's sort of like burning wood for power as opposed to burning coal - nobody who can help it is going to make a wood-fired power plant now that we have coal technology.

You mentioned several reason to think just that. Less mess, a more abundant fuel, less chance of something really bad happening.

I'm rather anti-fusion myself, mostly because of reading threads on various Traveller fan boards where fusion power is basically a replacement for thinking up real "futuristic" tech developments ("you know, this horse and plow thing isn't plowing these huge fields fast enough..." "How about a tilling machine?" "A what? No. The solution is a fusion-powered horse!" "Yeah, a fusion powered horse!").

Well, a horse is simply a power plant, to pull a plow through the earth. A tiller, regardless of how it is powered, is what does the job that is required. A fusion powered horse would be more versitile, able to do different jobs besides pulling a plow.

While I'm not a big fan of fission power myself, there's certainly plenty of more refinement that could be done with fission power - I think MGT writers have unconsciously got caught up in the fusion power meme and just sort of threw in fission as that dinosaur technology that some backwards groups use. The way that fusion power is often projected, fission doesn't have much place, but that doesn't necessarily have to be the case - you just have to put "holes" in fusion technology and find a use where fission might work better. Perhaps fission reactors can be more compact for the power produced than fusion (radiation shielding might be easier to handle than heat insulation so fusion reactors might have a bottom end of something the size of a small truck - by the time superior thermal shielding is developed, they're abandoning fusion for anti-matter).

I have my doubts about antimatter. Fuel is rare, and HIGHLY unstable. Very small amounts, very BIG energy release. Transportation and containment are going to be extremely big challenges. And fuel spills could be extremely catastrophic.

For instance, IMTU, all currently functioning Ancients devices are fission powered. Essentially, fusion power and anti-matter is too volatile and requires too much maintenance (there are devices of these sorts that would work if fuelled but they've long since ran out of fuel). However, the Ancients perfected fission power to a high degree, making it quite safe and able to deliver a consistent amount of power over very long periods of time (thousands of years) using isotopes with very long half-lives. The fission reactors don't produce enormous amounts of power, but for the Ancients, they found a "niche" for it which meant they continued to research it - low-to-medium power applications that would require a constant and largely unchanging amount of power spread over long periods of time in a hassle-free form.

I see your thinking here. Something like an RTG on the Cassini and other space probes, a self contained nuclear "battery". The thing is that fusion promises a higher energy density, more energy in a smaller space. It is an active process, versus a passive one, granted. But that is actually an advantage in most situations.

 

[Drakon]

As for making fission viable (filling a hole) something I did (around MT rules I think, maybe TNE) was make the fuel consumption the scale tipper. Sure fusion is volume efficient and cheap, but it drinks down LH2 like water so you've always got to be filling up the huge tank. While (in MTU) fusion was extremely fuel efficient (recycling spent fuel etc) so your "tank" of fusion fuel was good for a year or more*. I made it cost a little more to buy, and required special disposal too, but still the way I had it worked out there were applications where it beat fusion.

* after a year the power output starts to drop as the fuel is less and less recycled

Low power, long term stand alone power. For items that need power for long unattended duration. But note that without some technobabble, it will have a decaying power output over time.

Well not so much. You need a variable neutron absorber, a control rod. And it will require a drive mechanism, and control system. Shame you can't recycle the neutrons.

 

[ThunderChilde]

Ignoring the weird fuel requirments of traveller for a moment, the US Navy's later generation nuclear vessels go years to decades with being refueled, the power demands and out puts tend to increase over time, not decrease.

A point was made about nuclear waste, there wouldn't be much of it if it was reprocessed like the french do it, or the japanese for that matter. As for disposal, please, this is traveller, just ship it up and out and drop it into the local star. Eventually, you'll be contributing to the metal rich life cycle of steller evolution.

 

[Drakon]

Ignoring the weird fuel requirments of traveller for a moment, the US Navy's later generation nuclear vessels go years to decades with being refueled, the power demands and out puts tend to increase over time, not decrease.

Actually power requirements tend to be more or less constant over the life of a ship, if not go down. As equipment is upgraded, it becomes more energy efficient, thereby reducing power requirements. This is often mitigated by the fact that increased capabilities sometimes require more energy.

In a standard RTG, like is used on Cassini, it is essentially a lump of hot radioactive rock, or block, with a lot of thermocouples stuck in it. As time goes on, and the radioactive material decays, it does so in a logarythmic fashion. Power goes down over time.

The kind of nuclear power plants that the Navy uses, are essentially steam plants. They have an active control system to regulate the amount of radioactive decay and power output. But this system requires maintenence and you trade the simplicity of the RTG, for that control ability. You could build some sort of hybrid, but one thing you are going to need in the design is a highly reliable control system or you lose the main advantage of an RTG, its simplicity and longevity.

A point was made about nuclear waste, there wouldn't be much of it if it was reprocessed like the french do it, or the japanese for that matter. As for disposal, please, this is traveller, just ship it up and out and drop it into the local star. Eventually, you'll be contributing to the metal rich life cycle of steller evolution.

The waste produced from fission can only be reprocessed so often. And all the waste from the refining process is still radioactive. You are right that there will be less of it, but there will still be less waste and concentrated radioactive waste at that.

 

[ThunderChilde]

There is a new development in the solar power field that I believe would have application to RTGs. The idea is that you build a sealed black lined box, with voltaic cells around the perimeter. The glass and the back side relect some light on the cells as a scavenger process. The main power generation is done by a couple of gas filled cylinders. As the temperature rise in the box, the gases excite and generate high frequency sound waves that are converted directly to electricity by way of peizo-electric modules.

It is quite efficient, and much cheaper than a similar output voltaic array. It started life as an experiment to use new high efficiency thermocouples, and went over the left field wall.

Seems to me on the other RTG question that the solution is a simple voltmeter linked to a very basic stepper motor attached to the control rod. As the power begins to drop, the stepper motor slowly over time extracts the rod, or indeed inserts it if for some bizzare reason it begins to peak in output.