Congress funds NNSA’s modernization efforts through various programs and activities within the Weapons Activities appropriations account that generally address the following four areas: The stockpile area includes weapons refurbishments through LEPs and other major weapons alterations and modifications; surveillance efforts to evaluate the condition, safety, and reliability of stockpiled weapons; maintenance efforts to perform certain minor weapons alterations or to replace components that have limited lifetimes; and core activities to support these efforts, such as maintaining base capabilities to produce uranium and plutonium components. NNSA allocates funds to activities that directly support the stockpile area through Directed Stockpile Work within the Weapons Activities appropriation account. The infrastructure area includes government-owned, leased, and permitted physical infrastructure and facilities supporting weapons activities. NNSA’s 2016 nuclear security budget materials include information on two major types of infrastructure activities: (1) Infrastructure and Safety and (2) Readiness in Technical Base and Facilities, which includes two major construction projects. First, the Uranium Processing Facility is a construction project to replace enriched uranium capabilities currently located in the aging Building 9212 at the Y-12 National Security Complex. This project is part of a larger strategy to maintain NNSA’s enriched uranium capability by relocating enriched uranium operations performed in Building 9212 into other existing buildings by 2025 and by constructing a series of smaller buildings. Second, the Chemistry and Metallurgy Research Replacement construction project at Los Alamos National Laboratory, which is part of NNSA’s broader plutonium infrastructure strategy, is composed of subprojects to move analytical chemistry and materials characterization capabilities into two existing facilities. NNSA’s broader plutonium infrastructure strategy also includes the construction of at least two additional modular structures that the Fiscal Year 2016 Stockpile Stewardship and Management Plan reports will achieve operating capacity by 2027. The Uranium Processing Facility and the Chemistry and Metallurgy Research Replacement construction projects are both part of NNSA’s major modernization efforts. The research, development, testing, and evaluation area is composed of programs that are technically challenging, multiyear, multifunctional efforts to develop and maintain critical science and engineering capabilities. These capabilities enable the annual assessment of the safety and reliability of the stockpile, improve understanding of the physics and materials science associated with nuclear weapons, and support the development of code-based models that replace underground testing. The other weapons activities area includes budget estimates associated with nuclear weapon security and transportation, as well as legacy contractor pensions, among other things. The four areas are interconnected. For example, experiments funded under the research, development, testing, and evaluation program area can contribute to the design and production of refurbished weapons, which is funded under the stockpile program area. The infrastructure program area offers critical support to both the stockpile and the research, development, testing, and evaluation program areas by providing a suitable environment for their various activities, such as producing weapons components and performing research and experimentation activities. The U.S. nuclear weapons stockpile is composed of seven different weapons types, including air-delivered bombs, ballistic missile warheads, and cruise missile warheads (see table 1). NNSA’s 2016 budget estimates for modernization total $297.6 billion over 25 years, which is a slight increase from the 2015 estimates of $293.4 billion; however, for certain program areas or individual programs, budget estimates changed more significantly. The overall increase was moderated by a shift of two counterterrorism programs to another area of NNSA’s budget. Program areas increased by as much as 13.2 percent or decreased by as much as 18.1 percent. Within the stockpile program area, which experienced the biggest increase, budget estimates for some LEPs and an alteration increased significantly because of changes in production schedules and scope, among other things. According to the Fiscal Year 2016 Stockpile Stewardship and Management Plan, NNSA’s estimates for the next 25 years total $297.6 billion for modernization activities—an increase of approximately $4.2 billion, or 1.4 percent (in nominal, or current dollar, values), from the $293.4 billion NNSA reported in the 2015 plan. These budget estimates, which are for activities in the Weapons Activities area, are provided in the four areas discussed above: stockpile; infrastructure; research, development, testing, and evaluation; and other weapons activities. The overall increase was moderated by the shift of two counterterrorism programs from the Weapons Activities budget into NNSA’s separate Defense Nuclear Nonproliferation budget. The two counterterrorism programs that were moved out of the Weapons Activities budget together totaled approximately $8 billion. According to NNSA’s 2016 budget justification, this realignment is intended to provide greater clarity regarding the total funding and level of activity in the counterterrorism area. The realignment of these programs, along with other smaller decreases in the other weapons activities category, together accounted for an 18.1 percent decrease in the other weapons activities category during the 25-year period covered by the plan. Without the realignment of the two counterterrorism programs, the increase in NNSA’s overall Weapons Activities budget in the 2016 plan would have been considerably larger, totaling approximately $12.3 billion, or 4.2 percent, over the 2015 Weapons Activities budget. Table 2 details the changes in NNSA’s 25-year budget estimates from 2015 to 2016 for the four main areas in which modernization efforts are funded under Weapons Activities. In addition, budget estimates changed significantly for certain program areas and individual programs. Notably, the 2016 budget materials estimate that during the next 25 years, $117.2 billion will be needed for the stockpile area, which is an increase of $13.7 billion, or 13.2 percent, over the prior year’s budget materials. Part of this increase resulted from the addition of approximately $3 billion to support the Domestic Uranium Enrichment program, as well as increases in estimates for weapons refurbishment activities, particularly LEPs, as discussed later in this report. The 2016 budget materials indicate a decrease of approximately $1.8 billion for infrastructure activities during the next 25 years, compared with the 2015 estimates, in part because of reductions in recapitalization and site operation budget estimates. The 2016 budget materials increased proposed spending on research, development, testing, and evaluation activities by approximately $900 million during the same period. This increase resulted in part from an increase in estimates for the Inertial Confinement Fusion Ignition and High Yield program. Budget estimates in the Fiscal Year 2015 Stockpile Stewardship and Management Plan cover 2015 to 2039, while those in the 2016 plan cover 2016 to 2040. We compared the two sets of estimates by summing up the current dollar values for each, which is how NNSA reports the estimates. The total from the 2016 plan is different from the 2015 plan’s total in that the former includes the year 2040 and excludes the year 2015. Because of the effect of inflation, this comparison could make the difference between the 2016 projection and the 2015 projection appear higher than it would be in the case of a comparison of the two series in real dollar values or in a comparison that looks strictly at the years that overlap from each plan. In the Fiscal Year 2016 Stockpile Stewardship and Management Plan, estimates for some major modernization projects increased significantly from those in 2015. Specifically, regarding the weapons refurbishment efforts—which are captured within the stockpile category in the budget— the 2016 budget materials indicate that during the next 25 years, $49.8 billion will be needed to support LEPs and other weapons alteration activities, which is an increase of $8.2 billion, or 19.6 percent, compared with the prior year’s estimate of $41.7 billion. This increase resulted partly from the change in the scope and schedule for some programs, as discussed below. The W88 Alteration 370 effort expanded to include a conventional high explosive replacement while retaining the original schedule for a first production unit in 2020. To support this replacement, NNSA shifted planned spending for other programs—including $15.1 million originally planned for the W76-1 LEP—toward this effort. The Fiscal Year 2016 Stockpile Stewardship and Management Plan reported that the agency also shifted planned spending intended for surveillance of B61 and B83 bombs into the conventional high explosive replacement effort. The Fiscal Year 2016 Stockpile Stewardship and Management Plan estimated the total cost for the W88 Alteration 370 at $2 billion over the 25-year period covered by the plan, while the 2015 plan estimated the total cost at $1.2 billion, for an increase of approximately $0.8 billion. The cruise missile warhead LEP (renamed the W80-4 LEP) now has a first production unit planned for 2025—2 years earlier than the first production unit in the 2015 plan. This shift in schedule is intended to align with revised Air Force plans for the carrier missile. The Fiscal Year 2016 Stockpile Stewardship and Management Plan estimated the total cost for the LEP at $8.2 billion over 25 years, while the 2015 plan estimated the total cost at $6.8 billion, for an increase of approximately $1.5 billion. The Fiscal Year 2016 Stockpile Stewardship and Management Plan included a budget estimate for the B61-13 LEP that did not appear in the 2015 plan. This LEP, which NNSA officials stated is intended to replace the B61-12 LEP, is currently planned to begin in 2038, with an estimated cost of approximately $1.2 billion from 2038 through 2040.