A new, 10-year strategic plan for the U.S. nuclear weapons complex demonstrates that as the size of the arsenal shrinks because of a new arms control treaty with Russia, the effectiveness and life span of the United States’s weapons will increase.

Among the “select initiatives” listed by the National Nuclear Security Administration (NNSA) in an update released Wednesday of its 2004 strategic plan are life-extension programs for two nuclear missile warheads and one type of bomb.

Life extension for the W-76, the most numerous nuclear warhead in the U.S. stockpile, was initially approved in 2000. At first only 800 were to be refurbished, but the Bush administration raised that number to 2,000; the number now being refurbished is classified. The program will not be completed until 2018, according to the plan.

An initiative listed for completion by 2017 is a study for extending the life by some 30 years of the B-61 nuclear bomb. Some current B-61 models are strategic and carried by B-52 and B-2 stealth bombers, and other versions are tactical, carried by U.S. and NATO fighter planes based in Eu6rope.

While the NNSA paper does not reveal costs associated with these programs, a Government Accountability Office report this month, first disclosed by Hans M. Kristensen of the Federation of American Scientists, puts the estimated expenditure for the B-61 program at $4 billion through 2022, when the program is scheduled to be completed.

The goal is to combine several B-61 models into one, which will have varied explosive power and a very low yield, thus saving nuclear material, according to the GAO.

The plan hails the dismantlement of older nuclear weapons as “tangible evidence of the U.S. commitment to move toward a world free of nuclear weapons,” a goal articulated by President Obama. But the NNSA reports that it will not be until 2022 before it expects to have taken apart all the nuclear systems retired before 2009.