Most current U.S. nuclear warheads were built in the 1970s and 1980s and are being retained longer than was planned. Yet they deteriorate and must be maintained. To correct problems, a Life Extension Program (LEP), part of a larger Stockpile Stewardship Program (SSP), replaces components. Modifying some components would require a nuclear test, but the United States has observed a test moratorium since 1992. Congress and the Administration prefer to avoid a return to testing, so LEP rebuilds these components as closely as possible to original specifications. With this approach, the Secretaries of Defense and Energy have certified stockpile safety and reliability for the past 12 years without nuclear testing. NNSA argues it will become harder to certify current warheads with LEP because small changes may undermine confidence in warheads, perhaps leading to nuclear testing, whereas new-design replacement warheads created by the RRW program will be easier to certify without testing. Critics believe LEP and SSP can maintain the stockpile indefinitely. They worry that untested RRWs may make testing more likely and question cost savings, given high investment cost. They note that there are no military requirements for new weapons. Others feel that neither LEP nor RRW can provide high confidence over the long term, and would resume testing. Another point of view is that either LEP or RRW will work without nuclear testing. This report provides background and tracks legislation. It will be updated to reflect final FY2010 congressional action on RRW. See also CRS Report RL33748, Nuclear Warheads: The Reliable Replacement Warhead Program and the Life Extension Program, by Jonathan Medalia, which compares these two programs in detail.

Underground facilities are used extensively by many nations to conceal and protect strategic military functions and weapons' stockpiles. Because of their depth and hardened status, however, many of these strategic hard and deeply buried targets could only be put at risk by conventional or nuclear earth penetrating weapons (EPW). Recently, an engineering feasibility study, the robust nuclear earth penetrator program, was started by DOE and DOD to determine if a more effective EPW could be designed using major components of existing nuclear weapons. This activity has created some controversy about, among other things, the level of collateral damage that would ensue if such a weapon were used. To help clarify this issue, the Congress, in P.L. 107-314, directed the Secretary of Defense to request from the NRC a study of the anticipated health and environmental effects of nuclear earth-penetrators and other weapons and the effect of both conventional and nuclear weapons against the storage of biological and chemical weapons. This report provides the results of those analyses. Based on detailed numerical calculations, the report presents a series of findings comparing the effectiveness and expected collateral damage of nuclear EPW and surface nuclear weapons under a variety of conditions.

Since 1985, military retirement has been funded prospectively on an accrual basis. A recommended change to service-specific imputations of normal cost would result in lower funding by the Army, Navy, and Marine Corps, and increased funding by the Air Force.

The announcement of a hydrogen fuel initiative in the President's 2003 State of the Union speech substantially increased interest in the potential for hydrogen to play a major role in the nation's long-term energy future. Prior to that event, DOE asked the National Research Council to examine key technical issues about the hydrogen economy to assist in the development of its hydrogen R&D program. Included in the assessment were the current state of technology; future cost estimates; CO2 emissions; distribution, storage, and end use considerations; and the DOE RD&D program. The report provides an assessment of hydrogen as a fuel in the nation's future energy economy and describes a number of important challenges that must be overcome if it is to make a major energy contribution. Topics covered include the hydrogen end-use technologies, transportation, hydrogen production technologies, and transition issues for hydrogen in vehicles.