Experimental Changes to Nuclear Engineering

A few caveats: I ran these tests in Creative mode uusing MineCraft 1.6.2, Forge .871 and IC2 .216-experimental. These designs worked for me for at least one full cycle without issue and shouldn't be a problem but there's an off chance that they'll reduce their surroundings to a glowing glass crater. The last one is especially touchy. All designs from the Reactor Planner use MOX rather than Uranium but are otherwise as shown. Output was measured by both the Nuclear Control add-on's reactor info panel and by the power stored in an empty MFSU bank attached to each reactor. These two numbers agree very well with each other.

First off is a simple no-brainer using two single-cell fuel rods and a pair of advanced heat vents, one heat vent per fuel cell. At a temperature of 0 this lackluster plant generated a mere 2 MEU at 20 EU/tick. Yes, those numbers are right, MOX only seems to last half as long as conventional Uranium so if you burn it at room temperature you'll only get half the energy, albeit at the usual power. However, if you leave the heat vents out until the reactor has reached a temperature of 90,000, Hot-MOX the reactor, and then pop them in at the desired temperature, this design will output 14.2 MEU. That's 7.1 times more power, 3.5 times more energy, courtesy of MOX higher efficiency with temperature. This design is thermal neutral so once you have it heated just keep refueling.

This one's still pretty simple but I prefer this design over the equivalent quad core because the heat vent arrangement is simpler, requiring no heat exchangers. Yield at T=0: 6 MEU at 60 EU/tick. Yield at T=78,000: 50.6 MEU at 506 EU/tick, 8.4 times more power and 4.2 times more energy than Uranium. I'm confused why this lower temperature design had higher MOX thermal efficiency. This design is also thermal neutral.

Here's a slightly brawnier reactor using over-clocked heat vents . OCHVs can be used with Hot-MOX but need to have good cooling to keep them from melting. The single fuel cell in the upper left corner puts out just enough heat to maintain temperature. At T = 0 this reactor generated 16.7 MEU at 167 EU/tick. The reactor planner says it should be 165 EU/tick but the slight core heat that comes with using OCHVs gave the MOX a ~1% boost. At T = 50,000 this set-up generated 97.5 MEU at 975 EU/tick. 5.8 times more power and 2.9 times more energy than you'd get from Uranium. Not bad for a pair of quad cells. The downside to OCHVs is that the design isn't thermally neutral. The OCHVs continue to cool the reactor after the fuel has spent itself so automation to either pop out the OCHVs or refuel the reactor rapidly is necessary if you don't want to mess about baking it up to T every cycle.

The previous design also highlights the fundamental trade-off inherent in MOX fuel. Larger, more efficient cores require more heat vents, allowing less heat capacity plating, lower maximum safe temperatures and lower MOX thermal efficiency. The solution is not to use heat vents but more compact coolant cells or condensators.

This little CRCS model is for Shneekey . It's still drop-dead simple but that's Hot-MOX. You want lots of space to fill with heat capacity plating so you don't want much of anything else. You'll need to swap the coolant out when it gets toasty and automation will be your friend for that, but that's CRCS. The empty slot in the upper left corner is for an optional heat vent to prevent gradual accumulation of heat during coolant swaps. With 6 quad cores, this reactor puts out a fairly hefty 640 EU/tick even at room temperature. At T = 77,000 the reactor produced a very impressive string of craters where the MFSU bank had been. The nuclear information panel says that it was putting out 4538 EU/tick. I didn't have automation set up for this design so I only ran it for 1% of a cycle but the total final yield should have been ~454 MEU, which is consistent with the efficiency observed in other Hot-MOX reactors at this temperature.

One or two things that you might want to be aware of with regard to the Nuclear Control add-on for IC2 experimental.

- There's a glitch in power consumption for the remote thermal monitor. If you use transformer upgrades in it it will happily chew through as much power as it can find, burning through a lapotron crystal in a little over a minute. This can be crater-makingly pesky if you lose power to it during bake-up and your heat vents don't get inserted before Tcritical.

- At present, nuclear control doesn't read the time remaining for MOX properly and just displays it as 0 even when the reactor is cranking out the EU. Annoying if you're trying to figure out how long your reactor's been running but otherwise harmless.

Quote from Omicron

The question is more: with the removal of heating cells, how do you reliably heat your reactor up, and more importantly, keep it hot?

My solution has always been to leave out some or all of the coolant and then use nuclear control to:
- 1) Switch the reactor off when it reaches the desired temperature.
- 2) Activate the export bus on an Applied Energistics ME network to add the necessary components to the reactor.

It only works easily if there's just one type of component that has to be added and all the rest of the space in the reactor is taken up. Otherwise you get coolant where you don't need it and not where you do. If properly designed and implemented you end up with a thermally stable reactor ticking along at just over the temperature you set in nuclear control. You can even get the ME network to countermand the shut-down signal and restart the reactor once all the components have been delivered.

Quote

And the second question is how to test EU/t, because last I checked (two
days ago), the EU-reader didn't work with the new e-net.

Nuclear control's reactor info panel seems pretty accurate according to comparisons I've made against the power stored in an MFSU bank after a full cycle.

Awesome breakdown, Speleomantes.

I'm scratching my head a bit at the data, though. Trying to map out the relationship between heat and MOX efficiency:

T=00,000: efficiency x1.0, runtime x0.5
T=50,000: efficiency x5.8, runtime x0.5
T=77,000: efficiency x7.1, runtime x0.5
T=78,000: efficiency x8.4, runtime x0.5
T=90,000: efficiency x7.1, runtime x0.5

That doesn't make any mathematical sense whatsoever! We see a trend towards higher output with higher temperatures, but even at virtually the same temperature (77k vs 78k) the recorded numbers varied by more than one full multiplier step. And at the high end it drops down.

I need to think about this some more... and maybe make some extra data points myself.

...Ooooh! So that's why the results didn't line up! Many thanks Thunder

That means you actually don't need heat plating at all to get full output. Which in turn means any design that's valid for uranium and has +/- 0 cooling factor automatically becomes valid for MOX fuel as well (with the caveat of OC vents and heat exchangers making it impossible to maintain heat between cycles).

Obviously heat plating makes it easier to edge your reactor as close as possible to the maximum, of course. My my, what a dangerous game we shall be playing...

So you need to run the reactor as close to max heat as safely possible, right?

And increasing max heat became nearly pointless...

Quote from Geggo

And increasing max heat became nearly pointless...

I wouldn't say that. It's much harder to keep a reactor at 95% of its max heat when it has 10k heat capacity vs a reactor with 50k capacity.

Quote from Omicron

I'm scratching my head a bit at the data, though.

You and me both. I wondered if it had something to do with single vs quad cells so I ran a few more trials and am now even more confused.

Results, such as they are:
- The system is a bit buggy and I had some difficulty with reproducibility. Not sure if this was IC2 or Nuclear Control having trouble reading the EU/tick properly.
- The relationship between T and efficiency is a simple linear one so long as you only change T and don't change the reactor design.
- The type of cell (single, dual or quad) has no effect on MOX thermal efficiency
- The number of cells in the reactor does change MOX thermal efficiency, with more cells giving declining efficiency.
- The arrangement of the cells significantly affects MOX thermal efficiency
- MOX thermal efficiency isn't just proportional to heat, it's proportional to the max heat of the reactor.

Just so I can stop writing it out every time, I'm going to use efficiency to refer to MOX thermal efficiency for this post rather than the traditional multi-cell, multi-neutron pulse efficiency that we know and love. Efficiency is measured relative to Uranium for a full standard Uranium fuel cycle, so MOX at T = 0 only manages 50% efficiency due to its shorter burn time.

So first off I built myself a simple little reactor. Every slot filled with heat-capacity plating except the two in the center. No vents, just plating and fuel. Then I added one or two fuel rods and watched the EU/tick change with T. With just one fuel rod, single, dual and quad cells all got the same results. Efficiency for any one MOX cell of any type equals 50% + 3.7% per thousand heat.

The same design but using two fuel cells rather than just the one gave different results. For any two MOX fuel cells (single, dual or quad, they all ran the same) efficiency = 50% + 3.28% per thousand heat.

Next I popped out two more thermal capacity plates to give me more room to add more cells and things got confusing.

At T = 75,000, 1 dual MOX cell in a reactor with 53 heat capacity plates generates 130 EU/tick (efficiency = 6.5). With 52 heat capacity plates it generates 132 EU/tick, 135 with 51, 138 with 50 and 148 EU/tick (efficiency = 7.4) if there are only 46 heat capacity plates. The same applies to single and quad cells, it's just easier to measure with dual cells.

What appears to be going on is that MOX thermal efficiency is just not proportional to heat but also to the percent of max reactor heat. Forget your heat capacity plating and multi-chamber reactors. A single-block reactor with just a dual cell at 8000 heat generates 84 EU/tick, 210% efficiency. A 6 block reactor packed with heat capacity plating at the same temperature puts out a measely 32 EU/tick, not breaking even with Uranium. IMO, this is an issue that needs to be addressed otherwise it becomes very easy to build powerful, dirt-cheap single-block MOX reactors like this one which is thermally stable and will generate 352 EU/tick at 8500 heat.

Next I tried three cells and things got really weird. All else being equal, at T = 75,000 three single MOX cells arranged in a straight line generate 250 EU/tick. The same three cells arranged in an L-shape produce just 225 EU/tick. With Uranium, both configurations produce 35 EU/tick.

I didn't bother with all the various permutations of four cell arrangements. At this point I figured that there were too many confounding variables and gave it up.

I'm on the fence with this. Part of me hopes that it's a bug that will get fixed because otherwise reactor design gets very tricksy. On the other hand, it would make things a damned sight more interesting and give us a whole lot more variations to explore.

Regardless, I now know why my first batch of numbers came out so oddly.

Quote from Omicron

That means you actually don't need heat plating at all to get full output.

That doesn't seem to be the whole story. I'm definitely seeing this but I'm also getting higher efficiency in my high-T reactors operating at their limits than I am with low-T reactors operating at their limits.

I'll do some test runs with MFSU storage to cross-check what Nuke Control is claiming and get back in a bit.

Did the last posters miss the post where Thunderdark showed the EXACT math that is done for finding the efficiency of a MOX reactor?
Basically it's (current_reactor_heat/max_reactor_heat_capacity) * 4.

Higher heat alone doesn't help much, it's just the difference between maximum and current that matters. Higher heat capacity reactors simply allow for a bit safer error margins near the maximum.

It may potentially be an exact code snipped, but in any case it's not the entire math. It merely shows the heat scaling. There's a lot more than that involved in figuring out reactor EU output. Ignoring empiric data because you think you saw a formula is not a good idea.

As long as your system is properly primed then how "Tight" your automation is wouldn't matter. When I used cooling reactor set ups I always felt safer being able to run at least a quarter cycle without any cooling.

Quote from ShneekeyTheLost

If you don't have a tight automation, then you might get enough extra heat to blow up your reactor.

Given the amount of heat being generated I think you're going to want a system that shuts the reactor down while coolant is being refreshed. It'll cost you a few seconds every microcycle but given a ~3 minute microcycle with a ~3 second swap-out delay I'll take the small loss in efficiency for a lack of cratering.

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I was thinking about something like this
setup with MOX fuel.

That would work well as a conventional Uranium reactor but for MOX it suffers two problems.

First, those OCHVs are going to prevent it from being thermally stable. Once the reaction stops the reactor will cool and need to be reheated. Easier and safer to heat it up to the desired operating temperature once and have it stay there indefinitely.

Second, all that equipment in the core takes up space that you could be using to increase your Tmax and that is turning out to be important too. See my next post.
-S

OK, back from my vacation to the "real" world.

First off we have three trials on effects of operating temperature using the Munchkin series of Hot-MOX reactors. As kind as it was of Thunderdark to post that code snippet the data suggest that it isn't the full story. My thanks to Thunderdark for that too. Tinkering with these experimental versions is much more fun if you don't have a full manual written out for you.

The Munchkin series is named for their ability to crank out nearly 500 EU/tick from a single block reactor with nothing more than heat vents. The Munchkin 0 is a fairly simple little monoblock with just MOX dual fuel cells and advanced heat vents. The Munchkin I is virtually identical but has the empty space down the center paved with heat capacity plating. The Munchkin VI is a six-block reactor, identical to the Munchkins 0 and I in terms of fuel and heat vents but with a whole lot more heat capacity plating. All three are thermally neutral and, if they were conventional Uranium reactors, would be expected to generate 16 MEU/cycle.

All three reactors were cooked up to exactly 85% of the maximum temperature: 8500 heat from the Munckin 0, 18,700 for the Munchkin I and 79,900 for the Munchkin VI. All three reactors were then connected to MFSU banks and had brand new heat vents and MOX fuel inserted and were then run for a full MOX cycle. Power is reported from the Nuclear Control Reactor Info Panel, Energy was obtained from what was stored in the MFSU at the end of cycle. These two independant checks of output agree to within +/- 0.1% in all three cases.

The Munchkin 0 yielded 35.2 MEU at 352 EU/tick for an efficiency of 220% Uranium. That's exactly what the code snippet posted by Thunderdark predicts. 0.85 * 4 + 1 = 4.4 but divide by 2 for MOX only lasting half as long as Uranium and you get 220%.

The Munchkin I, running at more than twice the heat, yielded 46.9 MEU at 469 EU/tick. That's an efficiency of 293% Uranium, 133% what the Munchkin 0 generated.

The Munchkin VI generated 66.8 MEU at 668 EU/tick. An efficiency of 418% Uranium, 190% of the Munchkin 0's output.

T = 8500, %MaxT = 85%, E = 35.2 MEU, P = 352 EU/tick, Eff(U) = 220%
T = 18700, %MaxT = 85%, E = 46.9 MEU, P = 469 EU/tick, Eff(U) = 293%
T = 79900, %MaxT = 85%, E = 66.8 MEU, P = 668 EU/tick, Eff(U) = 418%

So, percent of max heat is one variable but max heat is also important . Hotter MOX reactors are more efficient and heat capacity plating will be your friend.

But on to even stranger effects...

OK, this is a very odd effect that popped up while I was tinkering earlier today. I have now confirmed it from total EU stored in the MFSU.

These are two trials from the WTF series of reactors. The WTF-I and the WTF-L are identical except for the internal arrangement of components. In the I configuration, three single MOX cells are arranged in a row. In the L configuration, the three MOX cells form a right angle. In both cases, the two outer cells receive 2 neutron pulses and the inner one receives 3. The two designs are identical except for shape. If these were conventional Uranium reactors, both designs would be expected to output 7 MEU at 35 EU/tick.

At T = 0, both reactors behave identically, giving 35 EU/tick. No surprise there, but turn up the heat and things get odd.

Both reactors were run up to 88,400 heat (85% Tmax), fresh MOX cells and heat vents were added, MFSUs were connected and then both reactors were started simultaneously and run for a full MOX cycle. P was read from Nuke Control's Info Panels and E was measured from MFSU storage after end of cycle.

WTF-I: T = 88,400, E = 29.3 MEU, P = 293 EU/tick, Eff(U) = 419%
WTF-L: T = 88,400, E = 27.6 MEU, P = 276 EU/tick, Eff(U) = 394%

So a 25% difference in efficiency just by changing the arrangement of the cells in the reactor?!? I'm not sure if this is intentional or an "undocumented user feature" but I think I like it. It will make figuring out the most efficient reactor design much more challenging.
-S

I've performed a few tests yesterday as well (though only a small number, due to limited free time), and my findings back up those of Speleomantes. There is definitely a correlation between maximum reactor heat capacity and EU output, but it doesn't seem linear at first glance. Diminishing returns at the high end? I need more data.

As for the WTF effect described just above... ... ... okay, I got nothin'. WTF! :p