RPC-XXX is to be contained within a chain-link fence along the perimeter of its containment site.
Try not to use the word "contain" twice in one sentence.
Any attempted intrusion into the RPC-XXX containment area is to be handled by Site 030 security personnel disguised as local law enforcement, in which security personnel are to escort civilians out of the containment area .
"In which" is not a proper connector in this context. Personally, I'd probably just remove everything after the comma; it can be easily inferred. Also, there's a stray space before the period here.
A cover story about a gas leak can be used for more persuasion.
"More persuasion" is silly phrasing. This is otherwise an odd detail, since the Authority usually doesn't need a cover story to remove a single person from an isolated location.
Any changes to RPC-XXX should be reported to Site 030.
This is common sense for any anomaly, really. The only context in which I would recommend including a sentence like this is if you're foreshadowing the existence of past changes in the anomaly's behavior.
The chair is extremely degraded due to its prolonged exposure to the outside
Minor suggestion: change "due to its" to "from". Alternatively, a word for "degraded from prolonged exposure to the outside" is "weathered".
causing the appearance of rust
Gramatically correct, but I would recommend using the verb "rusting" instead of the vaguer "the appearance of rust".
However, it seems that the current state of the chair is permanent, any traces of additional rust that appears on the metal parts disappears after a few seconds, it seems that it is impossible to degrade the chair more than it does.
The first comma should be a semicolon, while the second should be a period. Using rust as an example is odd since it's normally an uncontrollable factor; is the chair immune to physical force? In the third sentence, "does" is incorrect and should be replaced with something akin to "has already been", though really the entire sentence is redundant and should be removed.
RPC-XXX seems unable to be moved from its place of origin, or even to turn the chair.
The tense of "turn the chair" is inconsistent with the rest of the sentence. Say "be turned" instead.
When a subject sits on the chair, the subject will describe the chair as "the most comfortable chair I have ever sat on" usually adding the comment
Missing comma before "usually". Overall, this is a poor explanation of the effect, unless it's literally an impulse to vocalize that exact statement; avoid using non-specific quotes, as shown here, to explain effects as much as you can. Instead, try something like this: Subjects who sit on the chair will perceive it as extraordinarily comfortable, reportedly beyond comparison with any past experience in the subject's life. Subjects will commonly express a sentiment of being able to "die here with no regrets", or something similar.
It seems that when a subject is seated on the chair, this one would take part in a great production of endorphin in the brain of the victim, after an average of 23 seconds of exposure, the subject will not be able any more consciously get up from the chair.
"It seems that"? Don't hedge. Is it or is it not? Overall, this entire sentence has poor grammar and should be rephrased. Also note that there's a comma splice between "victim" and "after".
After that
Not a good connector for a clinical document. I don't think this connector is actually necessary, anyway.
on-site MRIs noted cortical atrophy including hippocampal atrophy that suddenly appeared in the affected subject's brain after 2.3 minutes
Why are you suddenly writing in past tense?
In 53% of cases the subject will develop Alzheimer's disease in the following seconds, in 46% Parkinson's disease will develop in a few minutes, in the remaining 2%, [FORGOTTEN] in nearly 32 minutes.
There should be a comma after "cases", and there should be an "and" after the last comma.
you tell yourself that nothing matters anymore because in a few seconds you will have already forgotten.
Missing comma before "because".
Subject will die after [FORGOTTEN] hours of agony.
Not clinical.
On [FORGOTTEN] 20██, Site 030 detected an intrusion into the RPC-XXX security perimeter, 3 agents were dispatched to the area as soon as possible, of the 5 teenagers who entered
Two comma splices: both of these commas should be periods.
the fourth having [FORGOTTEN] has a large oak tree, origin of the rope unknown.
This doesn't match up with the tense of the previous list items, and I can't make out what this sentence's structure is actually supposed to be. "Having _____ has"? What? Also, "origin of the rope unknown" isn't a complete clause, though that's debatably acceptable.
A note was reportedly found nearby
Was it found nearby or not? Don't hedge. If the "reportedly" is actually important, draw more attention to it, e.g. say that they couldn't locate it later.
It appears that any ocular perception of RPC-XXX is capable of transmitting the effect of RPC-XXX by some unknown means, destruction all archives containing an image of RPC-XXX requested [FORGOTTEN]. Reclassification requested, [FORGOTTEN].
Comma splice, and a missing "of" after "destruction".