Entergy Corp. announced that Mark Savoff, executive vice president and chief operating officer, and Jeff Forbes, executive vice president and chief nuclear officer, plan to retire, effective first-quarter 2016.

Both will transition to an advisory role beginning Nov. 1 until they retire.

Savoff’s successor will be named later.

Tim Mitchell, a 26-year Entergy nuclear veteran, has been named acting chief nuclear officer effective Nov. 1.

To fill the CNO role, Entergy will conduct an external search, including consideration of Mitchell.

Savoff joined Entergy in December 2003 as executive vice president, operations. In June 2010, he was given the added responsibility for nuclear operations and was named chief operating officer. During his tenure with Entergy, Savoff has led significant business projects, most recently the company’s operational transition to the Midcontinent Independent System Operator, or MISO, as the regional transmission operator; construction of the Ninemile Point Unit 6 plant; and optimization of the fossil fleet.

Forbes joined Entergy in August 2003, and previously served as senior vice president, nuclear operations, overseeing 11 nuclear units, before moving into the role of chief nuclear officer.