The Department cf Energy's Sandia National Laboratories are refurbishing the Spin Rocket Motor, a 1:rime component of the B61 nuclear weapon system. Both the originai motor produced i2 i906 and the version last produced in 1991 are the subjects of the refurbishment. Rvth motors, which are essentially identical, produce thrust to arm thz weapon. In Deceinber 2001, the National Nuclear Security Administration (NNSA) received Nuclear Weapons Council Standing and Safety Committee (NWCSSC) approval to study the feasibility and cost of replacement options. In April 2003, ihe MWCSSC approved the development of a new Spin ~ o c k e t h ~ o tboarse d on Sandia's assei-tiolls that test data collected between 1997 and 2002 showed the motors. due in largc: part to "detrimental aging," were not performing according to specifications. Detrimental aging occurs when a component's age prevents it from perfo~mingto meet military requirements. The first production unit for this refurbishment effort 1s scheduled to be completed in December 2006, at an estimated overall project cost of about $60 rnilllcn.