Nuclear stomach

The Nuclear Stomach drastically reduces a pawn's hunger rate to just one-quarter of its normal value and prevents food poisoning, however it causes an elevated rate of cancer. Like a bionic stomach, it also provides 125% part efficiency.

Shocking a pawn with this stomach using EMP will force them to vomit.

Acquisition

Nuclear stomaches can be crafted at a fabrication bench once the artificial metabolism research project has been completed. Note that this research requires a techprint. Each requires 15 Plasteel, 4 Advanced components, 26,000 ticks (7.22 mins) of work modified by the general labor speed of the crafter, and a crafting skill of 8.

Alternatively, they can be purchased from traders and outlander and empire settlements.

Summary

Body part

A nuclear stomach replaces the user's organic stomach. The nuclear stomach has a part efficiency of 125%. This not only fully replaces the functionality of a normal stomach - when coupled with the stomach body part having a Digestion importance of 50%, it results in an increase in Digestion of +12.5% over natural. Digestion, in turn, improves the rest rate multiplier by +3.75%, meaning the colonist will require slightly less sleep.

Eating capacity and eating speed are unaffected.

Other effects

A nuclear stomach reduces the hunger rate of a pawn by 75%, meaning they only require 1/4 the food to live. Contrary to what is displayed on the item info card this effect is applied as an offset to the hunger rate instead of a multiplier. All artificial stomachs are immune to gut worms, and installing one will instantly cure the disease. A nuclear stomach also grants full immunity to food poisoning. Unlike the bionic stomach, but similar to the other Royalty DLC stomach replacements, EMPing a pawn with a nuclear stomach will force them to vomit.

However, it also causes a carcinoma on the torso of the host pawn on average once every 120 in-game days.

Installation

Installing the part requires 2,500 ticks (41.67 secs) of work, 2x medicine of herbal quality or better, and a Medical skill of 5.

Removing the part requires 2,000 ticks (33.33 secs) of work, 1x medicine of herbal quality or better, and has no Medical skill requirements.

If the operation fails, the part will be destroyed.

Analysis

The nuclear stomach is a cheaper way to reduce time sleeping than upgrading to a royal bed, however both can be combined.

It is worth considering installing nuclear stomachs on slaves late game, since it reduces the food cost and slaves can be replaced easily if the surgery for the cancer fails or isn't attempted. The stomach can even be removed from the slave before death to implant into their replacement once it becomes clear that the cancer will be fatal.

While EMP-wielding enemies are relatively rare, due to the induced vomiting, friendly fire is a relevant concern on melee pawns as using EMP grenades and melee attackers on Centipedes is a common and successful tactic. Having a nuclear stomach on those melee pawns will result in them vomiting and negatively affecting this tactic and others like it. However, this can also be exploited against enemies with part, as well as against escaping prisoners or rebellious slaves. For the latter two options however, use of an implant that causes brain shock may be more useful as it downs the pawn, rather than merely causes temporary vomiting.

It is important to note that since the hunger reduction stacks additively with hunger offsets such as smokeleaf high and neural superchargers, rather than multiplicatively, the effect may be much weaker than expected in combination of other modifiers.

Carcinoma

All the following calculations will assume industrial medicine is being used, and otherwise a near best case scenario (15+ skill doctor with bionic arms, clean hospital with vitals monitors, etc.).

There are two strategies to deal with carcinoma; treatment, or surgery.

First, surgery: all surgery has a 2% failure chance, and the "Excise carcinoma" surgery has a 25% death chance on fail. This means that for every carcinoma that grows, there is a 0.5% chance the pawn will die. You can expect to lose a pawn at around the 138th carcinoma, on average. This seems rather high, but you could get unlucky and have it happen sooner, especially if you use nuclear stomachs on many pawns.

The other option is treatment. Carcinomas are quite variable, having a random chance to grow or shrink on their own, independent of treatment. On average they take 111 days to cure with the best treatment, slightly shorter than the 120 day average carcinoma generation rate from the stomach. This means you can expect your pawn to nearly constantly have a single mild carcinoma, requiring a 1 medicine treatment every 4 days (15 medicine per year per pawn). Technically this also makes the body part have −25% efficiency, but nuclear stomach carcinomas generate in the torso, and torso part efficiency has no effect on any stat.

Treatment is the safer method to handle carcinoma, but takes more time for both the pawn and their doctor, and costs 13 more medicine per year. Neither method is strictly better, it depends on how severe you consider the 0.5% chance of death to be, and the value of the pawn.

Genetic synergy

The nuclear stomach has significant synergy with the gene system added by the Biotech DLC. As metabolic efficiency is one of the key costs to beneficial genes, the nuclear stomach's -75% reduction to the base hunger rate can reduce even the worst metabolic efficiency with a hunger rate of 225% to only 56% that of a baseline human. Furthermore, the carcinoma risk from the stomach can be totally negated by the Non-senescent gene.

Comparisons

The Royalty DLC introduced a number of stomach replacements to complement the base bionic stomach, each with their own advantages and disadvantages. All three of these variants include the benefits offered by the bionic stomach in addition to their unique benefits however they are also susceptible to EMP, causing the pawn to vomit uncontrollably for a short length of time.

Bionic Stomach

In comparison to the nuclear stomach, the bionic stomach eliminates the vulnerability to EMP and cancer risk in exchange for being vulnerable to food poisoning and requiring 4x as much food.

Sterilizing Stomach

In comparison to the nuclear stomach, the sterilizing stomach eliminates the cancer risk in exchange for requiring 4x as much food.

Reprocessor Stomach

In comparison to the nuclear stomach, the reprocessor stomach eliminates the cancer risk in exchange for vulnerability to food poisoning and requiring 3x as much food.

Stomach	Cost	Digestion	Hunger Rate	Food poisoning	Side effects	Market Value
Stomach	-	1x	1x			-
Bionic stomach	10+ 3	1.125x	1x	×50%		785
Sterilizing stomach	15+ 4	1.125x	1x			1,030
Reprocessor stomach	15+ 4	1.125x	0.75x			1,030
Nuclear stomach	15+ 4	1.125x	0.25x		Carcinoma	1,030
Fleshmass stomach	-	1x	1x		+8% Pain	??^{[Detail needed]}