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The Reliable Replacement Warhead (RRW) was a proposed new American nuclear warhead design and bomb family that was intended to be simple, reliable and to provide a long-lasting, low maintenance future nuclear force for the United States. Initiated by the United States Congress in 2004, it became a centerpiece of the plans of the National Nuclear Security Administration (NNSA) to remake the nuclear weapons complex. In 2008, the Congress denied funding for the program, and in 2009 the Obama administration called for work on the program to cease. ==Background== During the Cold War, the United States, in an effort to achieve and maintain an advantage in the nuclear arms race with the Soviet Union, invested large amounts of money and technical resources into nuclear weapons design, testing, and maintenance. Many of the weapons designed required high upkeep costs, justified primarily by their Cold War context and the specific and technically sophisticated applications they were created for. With the end of the Cold War, however, nuclear testing has ceased in the United States, and new warhead development has been significantly reduced. As a result, the need for high technical performance of warheads has decreased considerably, and the need for a longer lasting and reliable stockpile has taken a high priority. Prior nuclear weapons produced by the U.S. had historically become extremely compact, low weight, highly integrated, and low-margin designs which used exotic materials. In many cases the components were toxic and/or unstable. A number of older US designs used high explosive types which degraded over time, some of which became dangerously unstable in short lifetimes (PBX 9404 and LX-09).〔(W68 warhead at globalsecurity.org ) Accessed 2006-05-03〕〔(Warhead Accidents at Banthebomb.org ) Accessed 2006-05-03〕〔(Explosives section in nuclear weapons FAQ ) Accessed 2006-05-03〕〔(LLNL explosives accident training web page ) Accessed 2006-05-03〕〔( Relatives of 3 Killed in Blast At Nuclear Plant Lose Suit ) from Oct 3, 1981 New York Times, Accessed 2006-05-03〕 Some of these explosives have cracked in warheads in storage, resulting in dangerous storage and disassembly conditions.〔(DEFENSE NUCLEAR FACILITIES SAFETY BOARD - Pantex Plant Activity Report for Week Ending January 16, 2004 ) Accessed 2006-05-03 〕 Most experts believe that the insensitive explosives (PBX 9502, LX-17) currently in use are highly stable and may even become more stable over time.〔 Highs Explosives in Stockpile Surveillance Indicate Constancy. Science and Technology Review. Dec. 1996. http://www.llnl.gov/str/pdfs/12_96.2.pdf 〕 The use of beryllium and highly toxic beryllium oxide material as neutron reflector layers was a major health hazard to bomb manufacturer and maintenance staff. The long term stability of plutonium metal, which may lose strength, crack, or otherwise degrade over time is also a concern. (See Nuclear weapons design and Teller-Ulam design for technical context.) The question of whether the plutonium-gallium alloy used in the cores of the weapons suffered from aging has been a major topic of research at the weapons laboratories in recent decades. Though many at the labs still insist on scientific uncertainty on the question, a study commissioned by the National Nuclear Security Administration to the independent JASON group concluded in November 2006 that "most plutonium pits have a credible lifetime of at least 100 years".〔JASON group, (lifetime ) (20 November 2006), online at http://www.nukewatch.org/facts/nwd/JASON_ReportPuAging.pdf.〕 The oldest pits currently in the US arsenal are still less than 50 years old. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Reliable Replacement Warhead」の詳細全文を読む スポンサード リンク
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