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). 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 pits accepted for use in the stockpile per year. Production at Rocky Flats halted in 1989. Since then, the United States has made 29 such pits in total. Yet the Department of Defense (DOD) stated it needed the National Nuclear Security Administration (NNSA), the separately organized agency within the Department of Energy (DOE) that maintains the U.S. nuclear stockpile, to have the capacity to produce 50 to 80 pits per year (ppy). Pits are to be made at Los Alamos National Laboratory (LANL, NM) in the PF-4 building, potentially in proposed smaller structures called modules connected to PF-4 by tunnels, or in both. Pits are made by casting two hemishells, or half-pits, then welding them together. 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 directed NNSA to demonstrate the capacity to produce at a rate of 80 ppy for at least a 90-day period in 2027. Accordingly, this report takes as its focus how to move toward that requirement. Producing 80 ppy 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," such as an earthquake. It is measured in units of Pu-239 equivalent (PE). Space is laboratory floor space available for plutonium operations. This report uses "margin" to measure "enough." Margin 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 and MAR margins are separate; both must be greater than zero to produce pits at the specified rate. MAR and space also figure in analytical chemistry (AC), a production support function. AC determines the composition of very small samples of plutonium. The Radiological Laboratory-Utility-Office Building (RLUOB), which was completed in 2010 and is near PF-4, is to house most AC. There are figures for available space and MAR, but figures for space and MAR required to produce 80 ppy have never been calculated rigorously , so this report cannot determine what options would provide enough margin for producing 80 ppy. Nor can it address whether certain options could meet the 2027 date because time to implement them cannot be determined. Instead, the report presents 16 options that increase the feasibility of producing at a rate of 80 ppy rate by 2027. A decision will likely weigh such factors as margin, cost, schedule, throughput, and safety. DOD stated a need for NNSA to have a capacity to manufacture 50 to 80 ppy, and 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." Further, NNSA deferred to FY2030 the projected delivery of the first production unit of the warhead that might be the first to use a newly manufactured pit since 2011; certain retired pits might prove suitable for reuse, reducing the number of newly manufactured pits needed; and pit lifetime might be longer than currently expected. Thus equipment to produce 50 ppy with a single shift might meet the 80-ppy requirement with less cost and space than equipment to manufacture 80 ppy with a single shift because less equipment would be needed. On the other hand, a higher operating tempo would place more strain on the equipment while allowing less time to maintain and repair it, though this disadvantage would occur only with double-shift operations. A few production processes run continuously for more than one shift, so adding a shift would not increase their capacity. It would be harder to surge production beyond 80 ppy if necessary. LANL is on one side of Los Alamos Canyon; the city of Los Alamos is located on the other side. The Royal Crest trailer park, with several dozen trailers, is on the lab side. It contains the non-lab publicly accessible structures closest to PF-4, about 3,500 feet away. The next closest structures accessible by the public are in the city of Los Alamos, about 6,000 feet from PF-4, and the next closest such structures after those in Los Alamos are in White Rock, about five miles from PF-4. Royal Crest is the location of the maximally-exposed offsite individual (MEOI), the hypothetical person outside the lab boundary who would receive the highest radiation dose from an accident in PF-4 that released plutonium. If Royal Crest were no longer the location of the MEOI, and the road it is on were controlled by the lab so the MEOI was not on that road, the next closest accessible structure would be farther away. Typically, fewer radioactive particles are deposited per unit of area as distance increases, so dose to an MEOI would be expected to be less in Los Alamos than Royal Crest. Since the MAR ceiling in PF-4 depends on dose to the MEOI, reducing the dose to the MEOI would permit increasing MAR in PF-4. Relocating Royal Crest could permit an increase in MAR at PF-4 faster, and probably at less cost, than new construction. NNSA calculates dose to an MEOI from an accident at PF-4 using computer models. The models use assumptions on the amount and form of plutonium released into the atmosphere, mechanisms for releasing it from PF-4, wind direction and speed, temperature, humidity, and the like. Three changes to accident modeling might be made. First, use a different atmospheric transport and dispersion model. Second, assume, based on historical data during drills, that the doors to PF-4 are open for less time during an evacuation, permitting less plutonium to escape in an accident. Third, change time-of-day assumptions in the model. Particles disperse less at night, when winds are calmer. More dispersion occurs in the day, reducing dose to an MEOI at any spot. Yet more plutonium is at risk during the day, when technicians are working with it; at night, it is stored in a less vulnerable state. At present, the model assumes daytime MAR and nighttime dispersion. Harmonizing MAR and time of day would reduce calculated dose. Such changes in PF-4 accident modeling could reduce the calculated dose to the MEOI by several orders of magnitude. That reduction, if incorporated into PF-4's safety documents, would permit more than doubling the MAR permitted in PF-4. It would surely be faster and less costly to change the model and assumptions than to build a new plutonium building. At issue for Congress: would a change made to PF-4's MAR allowance by using the more realistic model increase risk to the public? If so, would the benefits obtained by using that model be worth the added risk? The Defense Nuclear Facilities Safety Board (DNFSB) monitors health and safety issues at DOE defense nuclear facilities. A DNFSB report of October 2014 stated in regard to PF-4, "an entire wall of legacy gloveboxes … contains degraded conditions that workers suspect has contributed to multiple contamination events during the past few years. LANL management does not currently have a plan to remove these gloveboxes in order to both eliminate the hazard and free up the considerable space for new programmatic work." Removing the gloveboxes would reduce the risk of a contamination accident, which would remove a room from service until the contamination was cleaned up, and would free up space. The gloveboxes will have to be removed eventually at the end of PF-4's life; there is a tradeoff between the advantages of removing them sooner and the drawback of incurring cost now rather than later. DOE imposes a MAR limit specific to each building handling radioactive material so the dose to nearby workers and the public from an accident would not exceed limits specified by DOE. For a given MAR, dose is calculated with a ten-factor "MAR-to-dose" equation that includes the damage the building sustains, the fraction of plutonium released into the atmosphere by the event, and others. Five variables would vary from one scenario to another; NNSA typically assigns them a very conservative worst-case, or "bounding," value to keep dose within guidelines. According to Kamiar Jamali, Associate Administrator for Safety and Health, Office of Nuclear Safety, NNSA, "Extreme conservatism is often intentionally exercised in safety analyses because it can pay dividends in simplified analysis and review efforts. However, the search for increased conservatism cannot be pursued without consequences. Extreme conservatism can lead to safety conclusions and decisions with significantly higher safety costs, which can make nuclear facilities, even those with very low hazard and risk profiles, prohibitively expensive." He proposed using the mean value for the variables "as the metric that is consistent with the concept of reasonable conservatism in nuclear safety analysis, as its value increases towards higher percentiles of the underlying distribution with increasing levels of uncertainty." (For purposes of safety basis calculations applicable to LANL, mean and median are very close together.) In the MAR-to-dose equation, using bounding values for a PF-4 accident calculation results in an estimated dose 35,000 times larger than when using median values.