This question came to mind while reading about Otto Hahn, Lise Meitner, Fritz Strassmann on the one hand and Seaborg on the other. A natural question ...what is the maximum theoretical transuranic element?
This question does not have a clear answer.
You probably address the superheavy elements problem (SHE). For the moment (imho), all observed superheavies decay by alpha particle decay. So there are two hunts -
- hunt for heavier and heavier superheavy element - can they exist?
- hunt for a (quasi-)stable superheavy element
The stability depends very much on the nuclear structure and the structure predictions depend on the models. There are models, that predict island of stability somewhere but until experimentally confirmed, nobody can tell about the validity of different models. This is really a terra incognita for nuclear models.
This is one of the current topics in nuclear physics. Look at the http://iopscience.iop.org/article/10.1088/1402-4896/aa53c1 e.g. This guy - Oganesian, has even an element named after him. Very unusual.