The paperwork contains detailed data on the amount of plutonium produced during each of several rounds of production at a now-shuttered plutonium reactor.
The official said the United States had not yet seen the roughly 60-page declaration but believes North Korea will say it has produced an amount of plutonium in the low 40-kilogram range, including estimates of waste.
That is enough to construct about a half-dozen nuclear bombs. North Korea stopped making plutonium and has begun disabling its nuclear facilities so they cannot be quickly restarted, but it still has its stockpile of radioactive material for now.
U.S. intelligence agencies have various estimates of the total amount of plutonium the North has produced, ranging from about 30 kilograms to 50 kilograms. The official said the United States believed the figures could be resolved through the verification process.
The official spoke on condition of anonymity to discuss closed-door agreements with the North Koreans. The official says that the U.S. will check North Korea's math through a combination of documents, interviews and visits to the reactor.
In the meantime, China is expected to distribute the new documentation Friday to the other nations negotiating with North Korea. Also Friday, North Korea plans to blow up the cooling tower at its Yongbyon nuclear facility in a symbolic move to show its commitment to the process.
A meeting of nuclear negotiators could follow on Monday in Beijing, at which talks will begin on the specifics of how the declaration will be verified.
The paperwork handed in on Thursday is in English, the official said. It covers nuclear production dating back to 1986.
It does not contain detailed information about North Korea's separate uranium production program or what North Korea may have done to help Syria build a reactor.
Concerns about those activities are addressed in a separate two-page document that was turned over to the United States in April, the official said. That document, known as a "confidential minute," will likely be attached to the longer declaration as an annex.
In the annex, the U.S. outlines its concerns about uranium enrichment and the nuclear cooperation with Syria. North Korea acknowledges those concerns and says it will cooperate to work out differences to "mutual satisfaction," the official said.
The United States, Japan, South Korea, China and Russia have been negotiating for North Korea to give up its nuclear program since 2005. North Korea missed an end-of-2007 deadline to turn over a full inventory of its programs and a description of its spread of nuclear technology to others.
The declaration is a linchpin for the nuclear disarmament deal the North has worked out over three years. During that time, the talks stopped and started several times, and the North exploded a test nuclear device in 2006.
