The fourth-generation Yury Dolgoruky was built at the Sevmash plant in northern Russia and was taken out of dry dock in April 2007. It will be equipped with sea-based Bulava ballistic missiles upgraded from Topol-M (SS-27) missiles.
"There still are issues with the placement of a nuclear reactor on board the submarine. Sea trials have been postponed until 2009 so that Sevmash specialists could deal with the remaining problems," the source said.
"The trials will start most likely after the spring thaw [in the Barents Sea]," he added.
Sevmash and Northern Fleet specialists conducted successful testing of the submarine's nuclear reactor on December 16, but Russia's state nuclear power corporation Rosatom has introduced heightened safety measures due to a recent accident on board the Nerpa nuclear-powered submarine and the failure of the test launch of a Bulava missile.
The failed submerged launch of the Bulava ICBM took place in December from the Dmitry Donskoi strategic nuclear-powered submarine in the White Sea, off Russia's northwest coast, targeting the Kura firing ground in Kamchatka, the Far East.
Russia earlier planned for the Bulava to enter service with the Navy in 2009. But a senior Russian Navy official said earlier this month that several more test launches must be conducted next year from the Yury Dolgoruky before a final decision to bring it into service was made.
The Yury Dolgoruky submarine is 170 meters (580 feet) long, has a hull diameter of 13 meters (42 feet), a crew of 107, including 55 officers, a maximum depth of 450 meters (about 1,500 feet) and a submerged speed of about 29 knots. It can carry up to 16 ballistic missiles.
Two other Borey-class nuclear submarines, the Alexander Nevsky and the Vladimir Monomakh, are currently under construction at the Sevmash shipyard and are expected to be completed in 2009 and 2011.
Russia's Navy commander, Adm. Vladimir Vysotsky, said in July that the construction of new-generation nuclear-powered ballistic missile and attack submarines was a top priority for the Russian Navy's development.
Under the Russian State Armaments Program for 2007-2015, the Navy will receive several dozen surface ships and submarines, including five Project 955 Borey-class submarines, two Project 885 Yasen nuclear-powered attack submarines, and six Project 677 Lada diesel-electric submarines.