Deuterium Tanks.

In Starship VL, the main fuel used for warp drive is deuterium. Tanks can be purchased in a variety of sizes. The deuterium can be replenished by buying it from another ship/starbase, taking it from a derelict ship or by ram scooping it up from space with the Bussard Collectors (if fitted).

Sediment builds up in the bottom of the tanks causing a very gradual loss of efficiency. Stirring the tanks replenishes this loss but the tank must be offline to perform this maintenance task. This task does not require any teams.

The tanks are stirred via injector nozzles that recirculate jets of deuterium. These jets require weekly maintenance or they will steadily decline in efficiency due to clogging.

The efficiency of the injectors drops by 1% per day. Injector efficiency can be restored by a maintenance crew at the rate of 1% per minute. These crews can either be assigned manually or via the ships shift roster screen (for regularly scheduled maintenance).

The deuterium tanks can be “poisoned” if the bussard collectors pass carbon down into the tanks. The carbon filters on the bussard collectors must therefore always be set to ‘on’ if they are being used to charge the tanks. If a tank is poisoned, then the efficiency is decreased based upon the amount of carbon ingested. The only way to clear out a tank is to dump the contents (either into space or at a starbase), run a tank clean maintenance crew for 6 hours and then refuel (either through the Bussard collectors or at a Starbase).

A tank can be fueled with normal Hydrogen (Deuterium is Heavy Hydrogen), however this is only 1% as efficient as Deuterium. A starship Captain in a bind might use it in an emergency to get the ship moving. The percentage of other gases (including Hydrogen) in the tank will reduce the overall efficiency of the fuel. All other gases do not provide any fuel and with the exception of carbon simply reduce the efficiency of the deuterium in relation to the deuterium:other gases ratio. i.e. A tank with a 50% Deuterium and 50% other gases would only provide fuel that was 50% efficient.

Carbon has the effect of actually cancelling out an equal amount of Deuterium, so a tank with 75% Deuterium and 25% carbon is actually only 50% efficient as the carbon takes up 25% of the tank and cancels out another 25% of Deuterium. Note carbon has no effect on normal hydrogen.

There are 6 cooling cores on each tank. Each fully working core is capable of cooling 50% of the tank – so two fully working cores are required to cool a tank. It does not matter how full the tank is, the whole tank must be cooled to maintain efficiency.

A map of 29 temperature monitors spaced evenly throughout the tank measure the spread of heat throughout the deuterium. Having a couple of faulty coolers on one side may result in increased temperatures in that area. These heat monitors will be displayed on the LCARS in a 3-D graph format to show hot spots. Each cooling core should undergo routine maintenance by an engineering team every week otherwise it runs the risk of failing. The maintenance crew can either be assigned manually or via the ships shift roster screen (for regularly scheduled maintenance).

If a cooling core health falls below 80%, then it fails. 

If the tank cannot maintain its cooling, then the temperature will slowly rise causing the deuterium to expand. Once the temperature reached 32°K, auto venting relief valves will vent the excess into space to protect the ship. This will reduce the amount of available deuterium in the tank, but the venting will reduce pressure, reducing overall temperature. As the deuterium temperature rises it will also lose efficiency – eventually becoming unusable (until it is cooled back to a suitable level 13.8°K).

This means that although the warp core may demand 243 kg/hour from the tank (and they will receive this volume) at 20°K it will only have the equivalent effect of 182 kg/hour. The drive system is clever enough to compensate for this though, so a demand for 243 kg/hour would provide enough deuterium to make up for the short fall, however the deuterium volume would actual reduce by 324 kg/hour.

It should be noted that clouds of deuterium floating in space can be picked up again by the Bussard collectors, but are also highly volatile and can be ignited by photon/quantum torpedoes.

The tanks can be damaged during battle/collision. Damaged tanks may leak deuterium (reducing the overall capacity of the tank). This damage must be repaired (by an engineering team) before the tank can be refilled (via the Bussard collectors or at a starbase). 

The tanks can be vented at 1% of full capacity per second. Venting the Tanks requires command authorization.

Damage to the tanks may also damage the cooling coils. The deuterium tanks are an attractive target for boarding parties; therefore standard operating procedures require that at least two crew members are assigned to guard each of the tanks during red alert situations. These crew members can be assigned manually or via the ships shift roster screen (as a red alert task). Whether they need to be guarded during yellow alert situations or during normal operations is up to the discretion of the captain.

Available upgrades to the Deuterium tanks are:

- Increased cooling coil efficiency
- Improved shielding

Power Requirements

Tanks are available in a variety of sizes from 1,000 to 60,000 cubic metres.

Stirring the tanks requires 1MW of power per thousand cubic metres of fuel. If this power is not available then the stirring will not activate.

Each cooling core requires 1MW of power at full load per five thousand metres of tank capacity. 

Dev Notes

In a Galaxy class starship from Star Trek, the Main tank is located in the engineering hull on Decks 26-29 and has a capacity of 63,200 cubic metres. The auxiliary tank can only hold 12,000 cubic metres of Deuterium and is located in the saucer section on decks 8 & 9.

 

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Loss of efficiency is approximately 0.1 to 1% of current per day. Stirring the tank replenishes efficiency at a rate of 1/60^th of 1% per minute.

 

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The risk of a cooling core failure is calculated as (T-6) * 0.1 % where T is the number of days since the last maintenance. This failure calculation is carried out at a random point in each 24 hour day for each of the cores. So for a core that has not been serviced in a month (30 days) the chance of failure would be (30-6) * 0.1 or 2.4% per day. For 6 cores this would be a 14.4% chance per day of a core failure.

 

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There is no degradation in ability between 81% and 100%. Each cooling coil can cool the 8 temperature probes around it by 1 degree every minute. Down to a minimum of 13°K. If the tank is not being stirred then all individual temperature probes will equalize based on the average temperature at a rate of 0.001°K per 100 milliseconds. If the tank is being stirred, then the probes will equalize at a rate of 0.01°K per 100 milliseconds.

 

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Each time the tanks vents 1,000 cubic metres of deuterium is released. This will drop the remaining deuterium temperature by 10°K. 

 

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Every minute, each un-cooled temperature probe rises by between 0 and 1°K. 

Efficiency is calculated as 100 – ((AverageTempK-15) * 5)

 

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Because each core is capable of cooling 50% of the tank, when all cores are operating at 100% health, each core is actually only running at 34% load. If the tank cannot be cooled, then the Deuterium will start to slowly warm up in the same manner as if the cooling cores were damaged.