Israel-Achumba joined safety King Mack, wide receiver Malik McClain, and running backs London Montgomery and David Kency Jr. in the portal.
This was McClain's second time entering the portal after transferring to Penn State last year.
Kency became one of five Nittany Lions to hit the portal Thursday.
Montgomery joined a slew of other Nittany Lions to hit the portal on Thursday.
Mack appeared in every game in 2023, primarily on special teams.
"With one year of eligibility left, I want to end my collegiate career on my terms. Healthy, in style, and in a dominant fashion."