Congressional Budget Office (CBO) released a document The Long-Term Outlook for the U.S. Navy's Fleet, which contains a testimony of Eric J. Labs, Senior Analyst for Naval Forces and Weapons, before the Subcommittee on Seapower and Expeditionary Forces Committee on Armed Services, U.S. House of Representatives on January 20, 2010 (via beSpacific).
The Navy plan calls for construction of a fleet of 12 ballistic-missile submarines of a new class, at the total cost of more than $80 billion. First submarine is expected to be authorized in 2019, with the initial funding for the nuclear reactor coming earlier, in 2017 (p. 11). The new reactors will presumably use HEU fuel, although this issue has not been discussed in the testimony.
UPDATE 02/05/10: Reactor plant design and development work for the OHIO-class replacement began in FY 2010 and will continue in FY 2011 and beyond. Manufacturing development and demonstration work, as well as development of new core technologies for the S8G Prototype reactor also began in FY 2010.