BKW, which itself is majority (52%) owned by the canton, said that closure by 2022 could be "a possible solution."
It added that it plans to make an investment decision on the continued operation of the Muehleberg plant by the end of 2013.
BKW also noted that immediate closure of the 390-MW-reactor would go against national energy plans for an "orderly" phase-out of nuclear energy.
Muheleberg started operation in 1972. A citizens' initiative, known as Muehleberg Off has been calling for the canton of Bern to seek for immediate closure of the plant.