several things that are just thoughts:
first, there were a few online resources that translated "kurzreinigen" with "tidy / tidy up." One resource was an Amazon review of a automatic coffee maker and disassembly required to clean it after several uses..
second, Merriam Webster posts one of several definitions of the verb "tidy" as "...to put things in order" or "...to make something neat and orderly in appearance..." such as tidy up after supper. As applying to a reactor, not likely.
third, a reactor is a vat or container used for industrial chemical reactions.
so while I agree there is probably a better choice out there, I do see some relevance why tidy may be somewhat applicable here. Maybe "kurzgereinigt" here is meant to "...quickly wipe out the reactor of debris / remaining liquids (like cake batter in mixing bowl) before starting the next batch (maybe ?). It would certainly be quicker than a full rinse or wash with soap and water or other cleaning agents.
Another option might be "cleaning or wiping up / out" the reactor. Maybe (?). something similar to #12 by lisalaloca
It's also subjective as to how we interpret the OPs original German text.
Anyhow, just some thoughts.....