Original sentence: A Typhoon class submarine can stay submerged for periods up to 180 days in normal conditions, and potentially more if necessity arises (e.Only the first of these submarines to be constructed, the Dmitry Donskoi, is still in active service with the Russian Navy, serving as a test platform for the Bulava (SS-NX-30) missile currently under development.The construction of an additional vessel (hull number TK-210) was canceled and never  completed.nuclear war)
Edited sentence: A Typhoon class submarine can stay submerged for periods up to 180 days in normal conditions, and potentially more if deemed nessasary (e.Only the first of these submarines to be constructed, the Dmitry Donskoi, is still in active service with the Russian Navy, serving as a test platform for the Bulava (SS-NX-30) missile which is currently under development.The construction order for an additional vessel (hull number TK-210) was canceled and never completed.in the case of a nuclear war)