"Technical problems" within the Department of Energy's aging nuclear-weapons-building complex have caused delays in delivery to the Air Force of a powerful new warhead for the Minuteman III missile and a new bomb for the B52.

An advanced nuclear warhead for the Army's Lance missile, which could be converted to a neutron warhead, has also been delayed, according to previously secret information delivered earlier this year to the Senate Armed Services Committee by Undersecretary of Defense William J. Perry. a

Perry's statement appeared in a committee hearing transcript that was declassified and recently released to the public.

According to Perry, the current weapons delays did not stem from shortages of nuclear materials such as plutonium and tritium. Rather, he said, they were associated with manufacturing problems related to the sharp increase from just two years ago in the numbers of warheads being produced.

Perry also said that the modifications to "deployment planning" caused by the delays "can be accepted without a major impact to our overall capabilities.

All three delayed weapons, Perry noted, "modernized existing capabilities."

The Mark 12A warhead is scheduled to go on 300 existing Minuteman III ICBMs. The newer warhead, like the one it will replace, has three separate bombs. But each new one packs the power of 340 kilotons, twice as big as the one it replaces. The Hiroshima bomb was 12.5 kilotons, or the equivalent of 12,500 tons of TNT.

The B61 bomb is another version of one already deployed. The newer one has a feature that allows the yield to be changed depending on the target.

The Lance warheads, 300 in all, represent the last portion purchased for the 56-mile-range weapon system that already is deployed in western Europe. The new one was supposed to be the first U.S. neutron weapon, but that feature has been delayed by President Carter.

Instead, the new Lance will be able to be converted to neutron with the insertion of a separate device which is not yet being produced.

Although not mentioned by Perry, production of the new 8-inch nuclear artillery shell has also been delayed for at least a year. It was pushed back when the Department of Energy did not have enough funds to finance its engineering development fully.

According to DOE sources, the costs of starting up the biggest U.S. nuclear weapons program in 20 years have been far higher than expected. In addition, DOE has encountered some equipment and management problems in gearing up the seven separate production plants around the country that make up the weapons building complex.

For three years, DOE officials have been unable to get Congress to provide the $500 million they said was needed to bring these facilities to a safe operating level.

Several of the plants, for example, are still using electrical distribution and other equipment that was purchased in the 1940s, during the days of the Manhattan Project.

A recent "long-range resources planning study," ordered by the National Security Council and conducted by the Pentagon and the DOE, has focused on the need to modernize the weapons building complex as well as review plutonium and tritium production needed in the years after 1984.

A presidential review committee met Thursday at the White house and began drawing up recommendations for Carter on modernizing and expanding the nuclear weapons building program over the next 10 years, according to informed sources.

Approval was given for a major, multilayer program to repair the deterioration of the complex.

In addition, a recommendation was approved to increase future production of plutonium and tritium to meet needs for nuclear weapons production five years from now.

To implement that decision, money will have to be approved for starting a controversial reprocessing plant in Hanford, Wash., or switching a reactor now operating there over to producing weapons-grade plutonium. It now turns out plutonium that can be used only in a power reactor.

Another option is restarting a mothballed reactor at Savannah River, S.C.

There is also the prospect that development will be pushed on an entirely new $3 billion production reactor to handle weapons production needs into the next century.

DOE sources said yesterday that the requirement for expanded plutonium production was based on assumption that the United States will increase the number of cruise missiles now planned, and build two nuclear weapons for the Navy -- the Harpoon and Standard missiles -- neither of which has been approved.

It also includes tritium that would be needed if the president decided to convert the Lance and 8-inch shell to neutron weapons.

According to one source, the White House plan approved Thursday "was done primarily for political purposes."

Conservative members of the Senate and House armed service committees have approved funds for increasing plutonium production and, according to one participant in the administration's study, "the White House doesn't want to appear weak on this one."

He added that, after the election, should President Carter win, he was sure another look would be taken at the need for additional nuclear material.

Meanwhile, however, plans are being put together that could lead to almost doubling the DOE weapons program budget for fiscal 1982. The administration sought $2.7 billion this year. DOE officials are talking about nearly $5 billion next year.