- The Raiders also placed G Vadal Alexander on the non-football injury list.
Helu and Townsend can return to practice once activated. However, if they remain on PUP list to start the regular season, they would miss at least the first six weeks.
Helu, 27, is a former fourth-round pick of the Redskins back in 2011. He spent four years in Washington before signing a two-year, $4.1 million contract with the Raiders last year.
Helu stands to make a base salary of $1.9 million for the 2016 season, but there has been talk that he could open camp on the roster bubble.
In 2015, Helu appeared in nine games for the Raiders and ran for 39 yards on 17 carries (4.3 YPC) to go along with nine receptions for 75 yards receiving and one touchdown.