Special Containment Procedures
Due to the number and distribution of SCP-118, containment of every specimen is impossible. Known SCP-118 Red Zones are to be closed off to all civilian marine vessels and divers under the guise of a military presence or other plausible cover story. Contacts in navies known to operate near SCP-118 Red Zones are to be utilized in order to minimize the passage of military vessels through the Red Zones. If any area within the Red Zone has a depth of less than 1500 meters, the restriction is to be applied to aircraft as well. All human activity in surrounding Yellow Zones is to be monitored, and any non-military vessels or individuals approaching the Red Zone are to be turned away. In the Red and Yellow Zones, protocol TOXIC HARVEST is to be followed to ensure the removal of devices generated by SCP-118. Furthermore, protocol CELL WATCH is to be followed to ensure the early detection of any emerging Red Zones.
Samples of SCP-118 can be stored using standard containment procedures for non-virulent anomalous microbes.
SCP-118 is a species of ocean-dwelling protista that is capable of assembling functional, self initiating, nuclear devices from materials present in ocean water. While SCP-118 is unknown and hence has not been classified by the scientific community, specimens resemble protists of the phylum Euglenophyta but have significantly increased levels of movement speed, nutrient storage capability and resistance to alpha radiation. Specimens of SCP-118 have been found in all of the world's oceans and seas.
When in a survivable salt water environment, specimens of SCP-118 will seek out materials including but not limited to iron, silver, copper, carbon, TNT, and uranium isotopes. When SCP-118 has located a material of interest the material is absorbed into the cell using a method dependent on the size of the material. Single atoms and molecules (mostly substances that are dissolved in the water) are passed through the cellular membrane through specialized protein pumps. Larger particles smaller than the cell itself are ingested through phagocytosis. Larger pieces will have particles torn off through an unknown mechanism, which are then absorbed using the first two methods. This "mining" occurs even in solid and hard substances, such as metal ingots.
Upon reaching a threshold of absorbed materials, specimens of SCP-118 will move towards an "assembly area" on the bottom of the body of the water they are present in and will contribute to the assembly of a nuclear device. The nuclear devices assembled are gun-type fission devices using Uranium-235 as their fissile material. Observation of devices in the process of being assembled show that the process starts with the assembly of a metallic rounded cylindrical casing for the device, followed by the creation of two sub-critical masses of uranium and the conventional explosives to propel them into each other. The mechanism by which SCP-118 enriches harvested uranium is currently unknown. (See Addendum 4). The device is then finished with the assembly of a Uranium-238 tamper where the two uranium masses will collide and the assembly of a trigger mechanism. SCP-118 appears to assemble the necessary components by adding minuscule amounts of material to an (initially) tiny material "seed". Differing atoms and molecules can be added to the same component and assembled components are not necessarily homogeneous. It is currently unknown whether SCP-118 builds on the seed atom by atom or by adding very small sub-micrometer fragments. The mechanism by which SCP-118 attaches new material to the seed seamlessly is unknown. The assembly time depends on the size of the device being assembled, water conditions and mineral availability but observations suggest that 300 days for a medium size device can be considered average.
Once a nuclear device is finished SCP-118 will detonate the device by completing a circuit in the trigger mechanism. Around 90% of the nuclear explosions recorded as a result of SCP-118 have had yields in the 20 to 35 kiloton range, although yields as low as 4 kilotons and up to ███ kilotons have been reported. Aside from cases involving human interference, failure to detonate has never been observed, as all nuclear devices recorded have either been detonated of their own accord or removed from the water prior to completion. Devices constructed by SCP-118 appear to be larger than man-made devices of similar design and yield, presumably due to the neutron moderating effect of the water that separates the uranium masses throughout much of the device's construction. A given assembly area typically has between one and three devices in the process of assembly at any given time, although as many as six at a time has been observed. In zones where multiple devices are being simultaneously assembled, the devices are separated by enough distance to prevent the detonation of one from destroying or setting off the other(s).
While the Foundation is unable to prevent civilians and other organizations from obtaining samples of SCP-118, its superficial similarity to existing species, few numbers (relative to all oceanic protista), lack of anomalous behavior outside material rich bodies of water, and the Foundation's standard monitoring of scientific studies at risk of uncovering information about anomalous biological species ensures that the chance of SCP-118's true nature being determined through cell samples is minimal.
There are currently six different active SCP-118 assembly areas known to the Foundation. While the natural disappearance of an assembly area has been observed, the current consensus among researchers assigned to SCP-118 is that elimination of assembly areas without massively noticeable effects is currently unfeasible (See Experiment Log 118 - Gamma for details). Thus, containment is to be established at SCP-118's assembly areas, to be designated "Red Zones", and surrounding "Yellow Zones". Furthermore, areas with elevated concentrations of SCP-118, "Zones of Interest", are to be monitored for signs of assembly areas.
Addendum-118-1 Following the USS ████████ Incident, the exclusion radius used when drawing red zones had been increased. Containment protocol TOXIC HARVEST has been updated.
Addendum-118-2 With the signing of the Partial Test Ban Treaty and growing number and capability of nuclear detonation detection methods in use, the consequences of nuclear detonations caused by SCP-118 have increased. Containment protocols have been revised in light of these facts.
Addendum-118-3 Due to the significant cost of containing SCP-118 Red Zones, the O-5 council has requested trials on possible methods to eliminate SCP-118 assembly areas.
Addendum-118-4 (Level 4 Clearance required)
Our research has determined SCP-118 enriches uranium by exploiting the fact that U-235 has a slightly greater preference for a high oxidation state than U-238. SCP-118 specimens which have harvested large amounts of uranium and are near assembly areas appear to develop specialized organelles resembling a series of thousands of vacuole-like chambers with mitochondria-like organelles within them, responsible for catalyzing reduction and oxidation reactions. In a given chamber, uranium is repeatedly reduced and oxidized. Compounds with uranium in higher oxidation states are transferred up the "chain" of chambers while compounds with lower oxidation states are transferred down the chain. This results in a small amount of highly enriched uranium at the very end of the chain.
Researchers and engineers at Research Sector █ have managed to create a prototype uranium enrichment device based on the principles employed by SCP-118. While the prototype was unable to produce weapons-grade uranium without using unreasonable amounts of time, it was successful in producing reactor-grade uranium, albeit at significantly greater cost than conventional methods. Despite its current limitations, the idea shows promise and I have forwarded our findings to the relevant front companies.