The Energy Department has completed the first life extension on a 1960s-era nuclear bomb that is part of the Pentagon’s strategic deterrent, a senior department official said yesterday.
“Completing the B61 first production unit is an important step in keeping our nuclear weapons stockpile safe and reliable,” said Tom D’Agostino, deputy administrator for defense programs at the Energy Department’s National Nuclear Security Administration.
The B61 gravity bomb is the oldest nuclear weapon in use and is carried on Air Force B-52 and B-2 bombers. It was first produced in 1967. The bomb is being upgraded by replacing some its 6,000 components that will make the bombs usable for at least another 20 years, Mr. D’Agostino said.
“What we’re doing is essentially ensuring that the Air Force and the military will have a reliable nuclear bomb for our nuclear deterrent needs,” he said.
The program began about six years ago with goal of completing the first upgrade by June 2006, a deadline met Wednesday. It involved a complex series of designs and operations involving the three nuclear-weapons laboratories, other nuclear-related facilities and numerous contractors, Mr. D’Agostino said.
So far, $170 million has been spent on the B61 upgrade program, and a total of about $470 million will be spent over 10 years on the effort, he said.
The bombs were nearing the end of their life cycle and at some point would have been regarded as unsafe and unreliable, Mr. D’Agostino said. However, the Pentagon needed the weapons and therefore the life extension was carried out, he said.
The B61 is a candidate for the Pentagon’s plan to develop a deep-penetrating nuclear bomb that could be used against underground or hardened targets, such as secret nuclear facilities in Iran or North Korea. That program is on hold because of opposition from anti-nuclear lawmakers in Congress.
Mr. D’Agostino said the number of B61s in the arsenal is classified but upgrading all the bombs will be completed by 2009. Private security specialists estimate that the Air Force has about 750 B-61s.
The bombs contain highly enriched uranium that is boosted by tritium gas and triggered by high explosives. They have yields ranging from 10 kilotons to 300 kilotons. A kiloton is the explosive equivalent of 1,000 tons of TNT.
The life-extension program is part of the military’s effort to maintain a nuclear arsenal without conducting underground nuclear tests.