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). 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. 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. Production at that rate requires enough "Material At Risk" (MAR) and space. 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. A CRS report provides a detailed breakout of PF-4's space and MAR usage. 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. 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. A combination of these and other options may be needed to meet the congressional requirement. 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. Relocate a Trailer Park at Los Alamos

This option holds the potential to increase MAR permitted in PF-4 faster and at lower cost than new construction. Improve Modeling of Atmospheric Dispersion of Plutonium

Compared to the current calculation, using a different computer model and different assumptions on plutonium dispersion reduces calculated dose by up to orders of magnitude. NNSA calculates dose to an MEOI from an accident at PF-4 using computer models. Increase Material-At-Risk Ceilings by Using Conservative Rather Than Very Conservative Assumptions

This option holds the potential to increase permitted MAR in PF-4 by several orders of magnitude by using different assumptions in a calculation. Dose is calculated for a MAR value using a ten-factor equation that includes the amount of damage the building sustains, the fraction of plutonium that is released into the atmosphere by the event, an individual's breathing rate, and others. Yet an increase in the MAR ceiling in PF-4 by a factor of less than ten, and perhaps less than two—especially when combined with other MAR reduction measures described in this report—would probably provide enough MAR to permit production of 80 pits per year in PF-4. (Rem is a measure of radiation dose.) Pu-238 is 277 times more radioactive than Pu-239, so while PF-4 housed less than 2 kg of Pu-238 in February 2013, it contributed about a quarter of PF-4's MAR. That would permit either a reduction in the space and MAR needed for these processes, though offset somewhat by added space and MAR needed for packaging the drums, or would permit existing equipment to process more plutonium in order to support a higher rate of pit production. Hydrochloric acid processing for recovering plutonium produces a substantial waste stream that requires further treatment. Since Pu-241 decay is the only source of Am-241, after passing aged plutonium through a final run of metal chlorination to remove Am-241, so little Pu-241 would remain that even if all of it decayed to Am-241, the latter would never reach the level found in 30-year-old WGPu, and the weapons laboratories have certified weapons with pits that old (and older) as acceptable for use in the stockpile. Pu-241 has the shortest half-life of the plutonium isotopes in WGPu. Options Involving Structural Modifications to PF-4

		Augment Seismic Resilience of PF-4

This option would increase permitted MAR, worker safety, and public safety. For example, it removed about 20 tons of combustible material from PF-4, mostly from the laboratory floor.
A pit is the plutonium core of a thermonuclear weapon. Imploding it with conventional explosives provides the energy to detonate the rest of the weapon. The Rocky Flats Plant made up to 2,000 pits per year (ppy) through 1989; since then, the United States has made 29 pits for the stockpile. Yet the FY2015 National Defense Authorization Act requires the National Nuclear Security Administration (NNSA), which manages the nuclear weapons program, to produce at a rate of 80 ppy for 90 days in 2027. How can that requirement be met?
Pits are to be made at Los Alamos National Laboratory's main plutonium facility, PF-4. To manufacture pits, a facility must have enough laboratory floor space and a high enough limit for Material At Risk (MAR), the amount of radioactive material a worst-case accident could release. Producing 80 ppy requires enough "margin," the space or MAR available to produce pits minus space or MAR required for that production rate. While space and MAR available have been calculated, amounts required to produce 80 ppy have never been calculated rigorously, leaving space and MAR needs undefined. Further, the report cannot address whether certain options could meet the 2027 date because time to implement them cannot be determined. Accordingly, this report presents 16 options that seek to increase the feasibility of producing 80 ppy by 2027, including:
The radiation dose an individual would receive from a worst-case accident determines MAR permitted in PF-4. A ten-factor equation calculates dose as a function of MAR. NNSA uses worst-case values in this equation, yet median values may provide sufficient conservatism. Median values reduce calculated dose by orders of magnitude, permitting a large increase in PF-4 MAR. Yet merely doubling permitted MAR might suffice for producing 80 ppy. Providing this increase through construction at PF-4 could be costly and take years. In determining MAR for PF-4, the closest offsite individual is at a nearby trailer park. Relocating it would place the next closest individual farther away. The added distance would reduce dose, permitting increased MAR in PF-4. Using a different meteorological model and different assumptions would greatly reduce the currently calculated dose, perhaps permitting doubling PF-4 MAR. Plutonium decays radioactively, creating elements that various processes remove to purify plutonium. One process generates byproducts; plutonium is recovered from them with processes that take space and MAR. Since the United States has tons of plutonium surplus to defense needs, byproducts could be dispositioned as waste. Pits use weapons-grade plutonium (WGPu). U.S. WGPu is about 50 years old. About nine-tenths of plutonium-241, a WGPu isotope, decays to americium-241 in that time. Since plutonium-241 is the source of americium-241 in WGPu, removing the current americium-241 would prevent WGPu from ever reaching its americium-241 limit, permitting reduction in equipment for that process and reducing worker radiation exposure. A plutonium isotope used in space probes, plutonium-238, is extremely radioactive. It accounts for a small quantity of PF-4 plutonium but a quarter of PF-4's MAR. Building a "module" near PF-4 for plutonium-238 work would free MAR and space in PF-4, so one module might suffice instead of two or three. To reduce risk of collapse, loss of life, and radiation release from an earthquake, NNSA increased the seismic resilience of PF-4. More steps are planned; more could be taken.
Achieving the congressionally mandated capacity will probably require choosing among options to create a package. MAR margin could be increased by relocating a trailer park, using a new meteorological model, installing rugged containers in the PF-4 production line, increasing PF-4's seismic resilience, and using less conservative assumptions in the MAR-to-dose equation. Similar choices exist for other options. At issue for Congress: What are the risks, costs, and benefits of the options? What is the optimum combination of options?
CRS Report R44047, In Brief: Options to Help Meet a Congressional Requirement for Nuclear Weapon "Pit" Production, by [author name scrubbed], is a condensed version of this report.