This is the third in a series of CRS reports on pit manufacturing. A "pit" is the core of the primary stage of a thermonuclear weapon. Its key ingredient is weapons-grade plutonium (WGPu), which is composed mainly of the fissile isotope plutonium-239 (Pu-239) along with small quantities of other plutonium isotopes. Detonating the pit provides the energy to detonate a weapon's secondary stage. During the Cold War, the Rocky Flats Plant (CO) made up to 2,000 "war reserve" pits per year (ppy). (A war reserve pit is one that has been accepted for use in the nuclear stockpile, as distinct from developmental or production prove-in pits.) Production at Rocky Flats halted in 1989. Since then, the United States has made 29 war reserve pits total for replacement in W88 submarine-launched ballistic missile warheads between 2007 and 2011. Yet as discussed in " Install Equipment with a Single-Shift Capacity of 50 ppy ," the Department of Defense (DOD) stated it needed the National Nuclear Security Administration (NNSA, the separately organized agency within the Department of Energy (DOE) in charge of maintaining the U.S. nuclear stockpile) to have the capacity to produce 50 to 80 ppy. This capacity, it is argued, would support nuclear weapon life extension programs, permit replacement of pits found to be defective, and address geopolitical developments. Pits are to be made at Los Alamos National Laboratory (LANL, NM) in the PF-4 (Plutonium Facility 4) building, potentially in proposed smaller structures called modules that would be connected to PF-4 by tunnels, or in both. In an effort to increase pit production capacity, Congress focused on inputs, such as requiring a plutonium processing building to be constructed by a certain date at a certain cost. However, in Section 3112 of P.L. 113-291 , the Carl Levin and Howard P. "Buck" McKeon National Defense Authorization Act for Fiscal Year 2015, Congress changed tack and focused on output. It directed NNSA to ramp up pit production and demonstrate the capacity to produce at a rate of 80 ppy for at least a 90-day period in 2027. (The legislation permits extending this deadline by two years under certain conditions.) Accordingly, while some argue that the capacity should be larger and others hold that it should be smaller, this report takes as its focus how to move toward 80 ppy, not whether it is the right number. Production at that rate requires enough "Material At Risk" (MAR) and space. DOE defines MAR as "the amount of radioactive materials … available to be acted on by a given physical stress." It is material that could be released by a disaster, such as an earthquake that collapses a building followed by a fire. It is measured in units of plutonium-239 equivalent to convert all types of radioactive material to a common unit. Space is laboratory floor space, in square feet, available for plutonium operations. To measure "enough," this report uses the concept of margin, which is space available for pit production and supporting tasks minus space required for them to be able to produce at a specified rate, and MAR available for pit production and supporting tasks minus MAR required for them to do so. Space margin and MAR margin are separate; both must be greater than zero to accommodate pit production at the specified rate. PF-4 has 60,000 square feet (sf) of laboratory space on its main floor. It supports many plutonium missions. Some involve pit production, such as pit fabrication (casting pits from molten plutonium) and purifying plutonium for use in pits; others include preparing plutonium-238 (Pu-238) for use as a power source for space probes, disassembly of pits and conversion of their plutonium to plutonium oxide, and surveillance of pits to check their condition. PF-4 has a ceiling on permitted MAR; as of February 2013, that ceiling was 1,800 kilograms Pu-239 equivalent. To provide perspective, in 2012 pit fabrication and plutonium purification accounted for 12,000 sf and 10,400 sf of PF-4's laboratory space, respectively; as of February 2013, they accounted for 295 kg and 143 kg Pu-239 equivalent of PF-4's MAR ceiling, respectively. A CRS report provides a detailed breakout of PF-4's space and MAR usage. MAR and space also figure in a function that supports pit production, analytical chemistry (AC). AC analyzes very small samples of plutonium to determine the content of impurities, alloying material, and different isotopes of plutonium. AC techniques include mass spectrometry, x-ray fluorescence, radiochemistry, and material assay. The Radiological Laboratory-Utility-Office Building (RLUOB), which was completed in 2010 and is near PF-4, is to house most AC; PF-4 is to perform some higher-MAR AC and AC support work involving larger samples, such as material preparation. RLUOB's MAR ceiling is 38.6 g Pu-239 equivalent, though NNSA is evaluating a proposal to increase that to 400 g. AC equipment requires substantial laboratory floor space, and RLUOB has 19,500 square feet of space ideally configured for AC. This report presents options that may increase margin, many of which NNSA and its laboratories are considering. However, while figures for space and MAR available for pit production exist, though they may need updating, figures for space and MAR required to produce 80 ppy do not exist because they have never been calculated rigorously. Accordingly, this report cannot find that one or more options would provide enough margin for producing 80 ppy or supporting AC. Instead, it presents a progression of options to move toward that goal: options not involving modifications to pit production processes; options involving modification to those processes but not structural modifications to PF-4; and options involving structural modifications to PF-4. While the options seek to increase the feasibility of producing 80 ppy by 2027, the report cannot address whether they could meet that date because time to implement them cannot be determined. Potential hurdles render schedules unpredictable. Construction may encounter delays. Moving equipment in PF-4, making structural changes, or changing plutonium processes must follow detailed procedures supported by extensive analysis. Organizations within DOE, oversight agencies, communities, nongovernmental organizations, and others may contest proposed changes to regulations or to assumptions used in calculations. Implementing such changes may be time-consuming; lawsuits may add delay. Efforts to develop new technologies may fail. This report considers 16 options. A combination of these and other options may be needed to meet the congressional requirement. While any combination can only be selected if it provides enough MAR margin and enough space margin, other factors will also enter into a choice among options by Congress and NNSA. These include: reducing cost; accelerating schedule (i.e., making capacity available sooner); increasing throughput, the rate at which pits are made or processes completed; improving worker safety, which includes reducing the risk of injury from building collapse, fire, industrial accidents, and radiation exposure; reducing the risk to the public from radiation exposure if PF-4 were to release a large quantity of plutonium as a result of an earthquake or major accident; and reducing radioactive waste. Each option contributes to increasing the feasibility of producing at a rate of 80 ppy by 2027. Table 1 summarizes the contributions of each option to that requirement; each section of the report begins with a few words highlighting the most important contributions of that option. This option holds the potential to reduce space requirements and cost, and to accelerate schedule. DOD has stated a need for NNSA to have a capacity to manufacture 50 to 80 ppy. As John Harvey, then Principal Deputy Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs, said in 2013, We established that requirement back in 2008 for a capability to produce in the range of 50 to 80 per year. That evolved from a decision to basically not take the path that we originally were taking with the Modern Pit Facility, but to go and be able to exploit the existing infrastructure at Los Alamos to meet our pit operational requirements. The capability at Los Alamos was assessed to be somewhere in the range of 50 to 80 per year that they could get with the modernization program they anticipated. The Nuclear Weapons Council looked at that number. It's a capacity-based number, and said it's probably good enough. We'll have to accept some risk, but it's probably good enough. As it happens, Los Alamos "estimates that a second shift would increase pit-manufacturing capacity by 60% so that establishing a 50-ppy capacity could supply 80 ppy using a second shift." This range leaves uncertain whether there will be a need for 80 ppy, or whether 50 ppy would suffice. Adding to this uncertainty are NNSA's decision to defer to FY2030 the projected delivery of the first production unit of the first interoperable warhead (IW-1), which might be the first to use a newly manufactured pit since 2011; the possibility that certain retired pits might prove suitable for reuse, reducing the number of newly manufactured pits needed; and the possibility that pit lifetime could turn out to be longer than currently expected. (Estimates of pit lifetime have increased. In 2003, pit life was thought to be 45 to 60 years. A 2007 study placed the intrinsic life for plutonium in most pit types in the stockpile at over 100 years. A 2012 study by Lawrence Livermore National Laboratory placed the figure at 150 years; Los Alamos raised uncertainty about that claim. ) Compared to equipment to manufacture 80 ppy with a single shift, installing equipment to manufacture 50 ppy with a single shift would reduce cost and space because fewer pieces of equipment would be needed.