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CHAPTER 3 THE PROPOSED ACTION AND ALTERNATIVES

Chapter 3 describes the Proposed Action, which is the Department's Preferred Alternative, and the alternatives to that Proposed Action. These alternatives include "no action" and the relocation of interim pit storage from Pantex Plant to one of four candidate sites. Following that discussion is a summary of the method whereby the Department identified candidate sites for receiving some or all of the plutonium pit storage function. Also addressed are alternatives that were considered but eliminated from detailed study in this EIS. Chapter 3 concludes with a summary comparison of the environmental impacts of the Proposed Action and Alternatives. Detailed discussions of these environmental impacts are presented in chapter 4 (for Pantex Plant) and chapter 5 (for the four candidate sites).

3.1 Range of Alternatives

The Preferred Alternative involves all of the different weapons activities historically performed at Pantex Plant, storage of up to 20,000 pits at the plant, and the possible implementation of six new projects.

The No Action Alternative involves all of the different weapons activities historically performed at Pantex Plant, storage of up to 12,000 pits, and the implementation of only previously funded projects. With this alternative, dismantlement would cease once a storage level of 12,000 pits has been achieved.

The Relocation of Interim Pit Storage Alternative involves all of the different weapons activities historically performed at Pantex Plant, relocation of storage of 8,000 or 20,000 pits to another site, and the possible implementation of six new projects.

The alternatives considered in this EIS are the Proposed Action, the No Action Alternative, and the Relocation of Pit Storage Alternative (for interim pit storage only). These are described in sections 3.1.1 through 3.1.3. The Department's Preferred Alternative is the Proposed Action.

The Proposed Action involves continuing operations at Pantex Plant, increasing the pit storage limit from 12,000 pits up to 20,000 pits, and the construction of several new projects. These new projects, outlined in appendix H, are analyzed at a project-specific level of detail. For each of these projects, there is a range of reasonable alternatives that include, as a minimum, a Proposed Project (i.e., implementing the proposed change) and not implementing the proposed project.

The No Action Alternative involves continuing operations with the limitation of ceasing weapon dismantlement after a storage level of 12,000 pits is reached. No new projects are included with this alternative. DOE also understands that the No Action Alternative does not satisfy the purpose and need for action for weapon disassembly or goals for enhanced management of wastes.

In the March 1996 Pantex Plant Draft EIS, the proposed construction of the Hazardous Waste Treatment and Processing Facility (HWTPF) was considered necessary for improving waste operational efficiency and safety and meeting regulatory requirements established in the Agreed Order. With offsite disposal shipments of mixed waste in 1994 and two shipments in 1996, as described in section 4.13.2.3 of this volume, and changes contained in the August 1996 Federal Facility

Compliance Act (FFCA) Compliance Plan Annual Update document, construction of the HWTPF is no longer considered a regulatory requirement. DOE's purpose and need for enhanced efficiency and safety of its current mixed waste, low-level radioactive waste, and hazardous waste operations remain and are discussed in greater detail in volume II, appendix H. Without the HWTPF, waste treatment and processing capabilities are greatly limited.

The Pit Storage Relocation Alternative involves continuing the operations at Pantex Plant, construction of several new projects, and relocating the storage of some or all of the pits to another site. The candidate sites for relocation of interim pit storage provide a range of geographical, operational, and environmental alternatives.

The types and numbers of weapons operations performed at Pantex Plant in any year are principally defined by the Stockpile Memorandum. The Memorandum is set by the President and authorized and funded by Congress. In order to fully encompass the operations of Pantex Plant, different levels of all of the types of operations that Pantex Plant can and has performed are assessed.

Because future stockpile requirements cannot be accurately predicted, this EIS examines the impacts of activity levels for operations on 2,000, 1,000, and 500 weapons per year (see section 2.2). Additional information about activities associated with stockpile management missions is in the Pantex Plant Programmatic Information Document (DOE 1996b).

Weapons disassembly operations and weapons assembly operations result in roughly equivalent impacts and are the dominant contributors to the impacts resulting from plant operations. Therefore, the mix of weapons operations that is assessed for each alternative is dominated by these operations. For the No Action Alternative, the operations mix is dominated by assembly operations, once the disassembly operations limitation of 12,000 pits in storage is reached.

The activity levels of operations on 2,000, 1,000, and 500 weapons per year are representative levels of Pantex Plant activity. The 2,000 weapons level represents recent and current levels of activity. The 1,000 weapons level represents the level that will most likely occur in the near future, if there are no changes in current directions in the Stockpile Memorandum. The 500 weapons level represents the minimum level of activity required at Pantex Plant to maintain all of its mission capabilities. An activity level ranging from 330 to 680 weapons per year is evaluated in the SSM PEIS. This is based on the remaining stockpile in the year 2005 and beyond, after the successful disassembly of up to 20,000 weapons.

In the Record of Decision that will follow completion of this EIS, the Secretary of Energy will consider the environmental impacts of each alternative along with mission requirements, technical factors, and the public interest. In balancing these considerations, the Secretary could decide to implement all or part of any alternative. Likewise, the Secretary may decide to include a particular aspect of an alternative in a decision to implement another alternative. For example, the Secretary could decide to implement the No Action Alternative, but include the construction of the HWTPF described in the Proposed Action.

3.1.1 Proposed Action

DOE proposes to continue nuclear weapons stockpile management operations and related activities at Pantex Plant; continue the interim storage of pits at Pantex Plant; continue transportation of nuclear components to the Savannah River Site (SRS), the Oak Ridge Reservation (ORR), and Los Alamos National Laboratory (LANL); and implement projects and facility upgrades at Pantex Plant consistent with fulfilling these missions for approximately 10 years. Specifically, the Proposed Action includes:

• Continued operation of Pantex Plant, including activities associated with the following stockpile management missions:
  • Assembly of nuclear weapons.
  • Disassembly of nuclear weapons.
  • Modification and maintenance of nuclear weapons.
  • Quality assurance testing of weapons components (surveillance).
  • Research and production of high explosives (HE) and weapons components.

Because future stockpile requirements cannot be accurately predicted, the Proposed Action will include impacts of activity levels for operations on 2,000, 1,000, and 500 weapons per year.

• Management of nuclear weapons components and materials as follows:
  • Increasing the maximum quantity of pits in interim storage at Pantex Plant from 12,000 to 20,000.
  • Continuing to transport highly enriched uranium (HEU) and depleted uranium components from Pantex Plant to ORR for storage or processing and staging those components pending shipment.
  • Continuing to transport tritium from Pantex Plant to SRS for storage and recycling and staging these reservoirs pending shipment.
  • Continuing to transport radioisotopic thermoelectric generators (RTGs) from Pantex Plant to LANL for heat source removal and storage. Some RTGs from disassembled weapons would be retained at Pantex Plant as spares for future use in weapons maintenance, modification, or replacement, as required.
  • Continuing to transport a few selected pits per year from Pantex Plant to LANL for surveillance, inspection, and testing.
  • Continuing demilitarization and sanitization of components (including demilitarization and sanitization of HE), equipment, and related materials, and burning of HE and HE-contaminated wastes at the Burning Ground in accordance with applicable Federal and State regulations.
  • Continuing to dispose of other items resulting from mission operations in accordance with regulatory requirements.

• Performing environmental protection and environmental restoration activities. Environmental protection activities include the management and stewardship of resources as previously noted in section 1.2.2.2. Restoration activities include site characterization to define the nature and extent of contamination, evaluating potential corrective measures, coordinating with State and Federal regulatory agencies, and performing corrective measures.
• Continuing routine Pantex Plant activities such as waste management, infrastructure and building maintenance, operations and equipment relocation and consolidation, routine modifications to buildings, general landscaping, cooperative agreements with universities, technology transfer activities, transportation of materials, and similar support activities.
• Continuing the transportation of nuclear weapons, nuclear components, HE materials, wastes, and other materials to and/or from Pantex Plant. Additional information describing onsite transportation activities is provided in section 4.12 of this volume of the EIS.
• Performing all required facility upgrades, modifications and replacement of facilities, and new proposed projects that are foreseeable at Pantex Plant, as described below:
  • A new HWTPF that would accommodate management of low-level, hazardous, and mixed waste. The facility activities would include DOE developed technologies capable of mixed waste treatment.
  • Modifications of existing facilities to provide a Pit Reuse Facility in Zone 12. This facility would allow non-intrusive modification of certain pits in order to enhance their safety and allow their future reuse.
  • Construction of a new Gas Analysis Laboratory in Zone 11 to replace a structure of World War II vintage. The facility would provide new analytical laboratory space with the requisite environmental controls for sensitive gas analysis equipment.
  • Construction of a new Materials Compatibility Assurance Facility in Zone 11 to replace a structure of World War II vintage. The facility would be used for the environmental aging and compatibility testing of nonnuclear weapon components.
  • Construction of a new Nondestructive Evaluation Facility in Zone 12 to replace a structure of World War II vintage. The facility would house operations such as radiography, ultrasonic analysis, digital imaging, penetrant testing, laser sampling, radiometry, and computer tomography of nonnuclear weapon materials.
  • Construction of a new Metrology and Health Physics Calibration and Acceptance Facility in Zone 12. The facility would provide the capability and capacity to perform health physics calibration and product acceptance control in support of the disassembly/assembly programs. The Health Physics Laboratory would provide necessary calibration and maintenance support for radiological instrumentation and monitors. The Product Acceptance Control Laboratory would provide the capability for calibration and support of product acceptance testing and equipment.
  • Operations involving an AT-400A pit repackaging system using existing bays in Zone 12 are planned.

These projects are further described in volume II, appendix H, except for the pit repackaging operation, which is described in sections 4.3, 4.13, and 4.14 of this volume.

Figure 3.1.1-1.--Location of Proposed Projects at Pantex Plant

Table 3.1.1-1.--Proposed Projects at Pantex Plant (.pdf)

Figure 3.1.1-1 shows the proposed location of these projects, and Table 3.1.1-1 presents relevant data for each project. This EIS provides the project-specific NEPA analysis sufficient for decisions on whether to implement each of these projects. There are two other projects underway which have already been through the NEPA process and have been determined to be in a class of actions that would have no significant environmental impacts (i.e., categorically excluded). Consequently, these projects, described below, are not analyzed in detail in this EIS:

• A Plutonium Resource Center that was approved by Congress and began operation in fiscal year 1995. The center is being developed to study environmental impacts of plutonium storage and future uses of plutonium. It occupies space in an existing commercial building in the City of Amarillo. No radioactive materials are handled or stored in the resource center. The NEPA review was approved in December 1994.
• The Burning Ground Upgrade project would consist of a covered, three-sided structure with a fan to exhaust emissions through an elevated stack. The wood currently used as an auxiliary heat source would be replaced by natural gas. The NEPA review for this project was approved in July 1994.

These projects have been taken into account in the evaluation of the impacts of each of the alternatives assessed in this EIS. It is foreseeable that within the next 10 years, actions (such as movement of pits within Zone 4 or modifications to security) may be required to implement third-party inspections of weapons facilities as a part of the National Nonproliferation Policy. These actions would be implemented to the extent feasible within existing capability. As the implementation of this policy has not yet been fully defined, these actions have not been through the NEPA process nor are they discussed in detail in this EIS.

3.1.2 No Action Alternative

The No Action Alternative includes the continuing and historical nuclear weapons assembly/disassembly operations and related activities of Pantex Plant; continuing the current nuclear components storage activities at Pantex Plant; continuing environmental protection and restoration programs; and continuing transportation of components to ORR, SRS, and LANL, as described in the Proposed Action.

This alternative differs from the Proposed Action in that:

• The six projects described in Table 3.1.1-1 would not be implemented.
• Weapons disassembly operations would cease when 12,000 pits have been placed in interim storage at Pantex Plant. Note, however, that all other stockpile management operations would continue. Because current mission requirements are dominated by dismantlement, a significant drop in the activity level would be expected to occur when dismantlement ceases. However, with the No Action Alternative, Pantex Plant still has the requirement to support the stockpile with other operations, including weapons production, modification, and surveillance activities. Because future stockpile requirements cannot be accurately predicted, the No Action Alternative includes impacts of operations on 2,000, 1,000, and 500 weapons per year.
• Only 12,000 pits from weapons disassembly would be placed in interim storage at Pantex Plant. No pits would be transferred to another site for storage.

It should be noted that the No Action Alternative would allow only partial fulfillment of the Pantex Plant mission, by limiting the amount of weapon disassembly, and would not fully satisfy the purpose and need for agency action discussed in chapter 2.

3.1.3 Relocation of Interim Pit Storage Alternative

With the Relocation of Interim Pit Storage Alternative, only the interim pit storage functions would be transferred to another site. The options detailed below describe how some or all of the pits currently or potentially stored at Pantex Plant would be stored at another site. With this alternative, all weapons operations (e.g., disassembly, assembly, etc.) would continue to be performed at the plant. The new projects (HWTPF, Pit Reuse Facility, Gas Analysis Laboratory, Materials Compatibility Assurance Facility, Nondestructive Evaluation Facility, and Metrology and Health Physics Calibration and Acceptance Facility) are needed to maintain the capability of the plant to perform weapons operations efficiently. Therefore, they are included in this alternative. Additionally, all other functions described in the Proposed Action, including the impacts of operations on 2,000, 1,000, and 500 weapons per year, were assessed for this alternative. This alternative examines the environmental impacts, at Pantex Plant and other sites, of relocating interim pit storage from Pantex Plant to other sites.

Specific features of interim pit storage relocation options are described below:

• Option 1ùRelocating interim storage of up to 20,000 pits from Pantex Plant to one of the following candidate sites: Nevada Test Site (NTS), about 104 kilometers (65 miles) northwest of Las Vegas, Nevada; SRS, 19 kilometers (12 miles) south of Aiken, South Carolina; and Kirtland Air Force Base (KAFB), just southeast of Albuquerque, New Mexico.
• Option 2ùRelocating interim storage of up to 8,000 pits to one of the following candidate sites: NTS; Hanford Site, just north of Richland, Washington; SRS; and KAFB.

With this alternative, the number of pits stored at Pantex Plant could conceivably be increased beyond 12,000 initially. Once the rate of pit shipments to an alternate site is sufficient to handle the number of pits generated by disassembly operations, the backlog of stored pits would begin to be transported and the number of pits stored on site would decrease. The maximum number of pits stored at Pantex Plant with this alternative would depend on the time needed to implement any required upgrades at the alternate site and the availability of a new container certified by the DOE under the requirements found in 10 CFR 71. Once the alternate site is operational and containers are available, shipments would begin.

For the relocation site alternatives, the EIS scope includes:

• Performing at Pantex Plant all operations, upgrades, and modifications of the Proposed Action.
• Performing at the alternative sites only those facility upgrades and modifications or replacement of facilities that would be needed to accommodate the interim pit storage mission. These sites and their respective storage facilities are described in chapter 5.

3.1.4 Selection of Site Alternatives for Interim Pit Storage

A DOE Site Screening Committee systematically evaluated the potential of DOE and Department of Defense (DOD) sites as alternative interim pit storage sites. The site screening process evaluated a large number of candidate sites to determine the range of reasonable alternative sites. This was accomplished by developing site suitability criteria, applying the criteria to candidate sites, and determining the best sites to represent the range of reasonable site alternatives.

Five exclusionary criteria were used to qualify sites for consideration as reasonable candidates. In order to be considered in the reasonable range, a site must be:

• Located within the boundaries of the 48 contiguous states of the U.S. and accessible during all seasons by all-weather highways.
• Currently owned by or transferable to the Federal Government.
• Available for use by DOE Defense Programs beginning in 1997.
• Under DOE control through at least 2007.
• Capable of storing a minimum of 8,000 pits.

Favorability criteria were then used to assess how well each remaining site was suited for the intended use. The favorability criteria were:

• Degree of construction required to adapt existing facilities for the pit storage mission.
• Degree of isolation from civilian populations.
• Indication of environmental hazards potentially impacting the intended mission.

After applying these favorability criteria to DOE sites and visiting finalist sites to look at the specific facilities that would be used for pit storage, DOE selected NTS, Hanford Site, and SRS as DOE site alternatives for interim pit storage.

In parallel to the committee's screening of DOE sites, the Nuclear Weapons Council Staff conducted a review of 60 DOD installations to determine which ones were feasible for the interim pit storage functions. Using the same site screening criteria, the Council Staff found that most of the examined installations either had military missions incompatible with pit storage or were too far into the base realignment and closure process to be made available to DOE. The Council Staff found that only two bases, KAFB (at Albuquerque, New Mexico) and the Seneca Army Depot (at Romulus, New York) appeared to be feasible for interim pit storage.

DOE then asked the Department of the Air Force and the Department of the Army to concur that these sites were available for DOE use and for each Department to become a Cooperating Agency for the preparation of this EIS. The Air Force agreed that sufficient storage area at the Manzano Weapons Storage Area (WSA) on KAFB could be made available and consented to be a Cooperating Agency. After a visit to the Manzano WSA to validate the suitability of the site under the site selection criteria, the Manzano WSA was confirmed to be in the reasonable range of alternatives and the impacts associated with interim pit storage at this site are analyzed.

Subsequent to the actions of the Nuclear Weapons Council staff, the Seneca Army Depot was placed on the 1995 Base Realignment and Closure (BRAC) list. Because of this, the Army and DOD could not make a determination as to its availability until the BRAC list was approved. The list was approved September 29, 1995, and Seneca Army Depot was approved for closure in accordance with the procedures established by the Defense Base Closure and Realignment Act of 1990 (Public Law 101-510). In accordance with these procedures and the Memorandum for Federal Agencies, dated September 29, 1995, Subject: Notice of Availability of Excess Real Property at Seneca Army Depot, Romulus, New York, it was determined that Seneca Army Depot would not serve as a viable alternative within the Pantex Plant EIS, because DOE cannot fulfill a key BRAC requirement in stating that none of its holdings and property can satisfy the purpose for which the base is sought. The requirement for storing nuclear weapons components can be accomplished with DOE's current holdings. Therefore, Seneca Army Depot was not considered further as an alternative pit storage location.

3.1.5 Alternatives Considered but Eliminated from Detailed Study

DOE considered three other action alternatives that were eliminated from detailed study in this EIS. These action alternatives were:

• Relocation of Pantex Plant operations.
• Shutdown of Pantex Plant.
• Relocation of storage for HEU, depleted uranium, tritium, and RTGs.

Each of these is discussed below in sections 3.1.5.1-3.1.5.3.

3.1.5.1 Relocation of Pantex Plant Operations

The original Notice of Intent (NOI) (59 FR 26635) for preparation of this EIS included the possibility of relocating some or all of Pantex Plant operations as part of the Relocation Alternative. Upon further review, it was determined that the relocation of operations from Pantex Plant within the time period of this EIS would not meet the purpose and need for DOE to maintain minimum disruption of weapons disassembly operations. As discussed in the Amended Notice of Intent (60 FR 32661), the SSM PEIS evaluated the relocation of Pantex Plant operations. This EIS incorporates by reference and summarizes impacts of relocating operations as identified in the SSM PEIS. These impacts are discussed in qualitative terms in the cumulative effects sections of this EIS.

3.1.5.2 Shutdown of Pantex Plant

The original NOI (59 FR 26635) also mentioned an alternative of shutting down Pantex Plant operations as a means of evaluating environmental baseline conditions. However, Pantex Plant is the only facility currently capable of carrying out the requirements to assemble, disassemble, and perform quality assurance tests on the nuclear weapons and weapon components. These activities are required to maintain the safety of the nuclear weapons stockpile. The near-term shutdown of Pantex Plant before any other facility could fulfill these responsibilities would result in the interruption of these safety requirements. Therefore, as announced in the Amended NOI (60 FR 32661), the shutdown of Pantex Plant operations within the near-term scope of this EIS is considered unreasonable.

3.1.5.3 Relocation of Storage for Nuclear Components Other Than Pits

The nuclear components (e.g., RTGs, HEU, and depleted uranium) resulting from the disassembly of weapons are either stored at Pantex Plant; stored or processed at LANL, in Los Alamos, New Mexico; or stored or processed at ORR, near Knoxville, Tennessee. Tritium pressure vessels are processed and the tritium is recycled at SRS, near Aiken, South Carolina.

The original NOI (59 FR 26635) suggested that DOE might consider relocation of current nuclear component storage activities to other DOE or Federal sites. However, after further review of the nature of the components being shipped to other sites and the operations that must be performed preparatory to storage, DOE determined that, for the time period of this EIS, there are no other sites with the capability and capacity to perform pre-storage operations and processes than the sites to which the components currently are sent. Thus, tritium must continue to go to SRS for recycling and storage pending reuse. HEU and depleted uranium components must continue to go to the Y-12 Plant at ORR for the specialized component separation, demilitarization, and declassification operations that can only be performed there. Likewise, RTGs must continue to be shipped to LANL, which is the only place where the capability and capacity exists to remove the plutonium pellets for storage or reuse.

Because of the uniqueness of these facilities within the Nuclear Weapons Complex, relocation of storage for nuclear components other than pits is not reasonable during the time period of this EIS. Instead, the detailed study of relocation of HEU, tritium, and RTGs is being assessed in detail in the S&D PEIS, the SSM PEIS, the Tritium Supply and Recycling PEIS, and the Highly Enriched Uranium EIS, as well as site-wide NEPA documentation for the impacted sites.

3.1.6 Preferred Alternative

The Council on Environmental Quality regulations require an agency to identify its preferred alternative(s) in the Final EIS (40 CFR 1502.14(e)). The preferred alternative is the alternative that the agency believes would best fulfill its statutory mission, giving consideration to environmental, economic, technical, and other factors.

Based on the analyses in the Final EIS and consideration of schedule and technical information, the Department's Preferred Alternative is to continue nuclear weapons operations at Pantex Plant; implement projects and facility upgrades consistent with fulfilling these operations; and increase interim storage levels for plutonium components (pits) from 12,000 to 20,000 pits.

3.2 Comparison of Environmental Impacts of Alternatives

Table 3.2-1 presents a comparative summary of the potential impacts to the environment at or near Pantex Plant that would be expected to result with implementation of the Proposed Action, No Action, and Pit Storage Relocation alternatives. The potential impacts that would be expected to result with implementation of the Pit Storage Relocation Alternative at Pantex Plant and the candidate sites are presented in Table 3.2-2.

For most of the environmental resources assessed in this EIS, there is no real difference among the impacts for the different alternatives. This is due to the nature of the activities described in each alternative. Each of the alternatives examines the activities at Pantex Plant in terms of three levels of activity for operations on 2,000, 1,000, and 500 weapons per year. The differences among the alternatives are in the number of pits that will be stored at Pantex Plant and the new projects that might be implemented.

Impacts to facilities and infrastructure, land resources, air quality, acoustics, cultural resources, socioeconomics, waste management, intrasite transportation, and environmental justice were determined to be similar for each of the alternatives. The main differences in impacts among the alternatives would involve the disturbance to soils and biotic resources due to construction of the new projects, radiation exposure to workers involved in the transfer of pits, and risks associated with aircraft accidents.

Table 3.2-2 presents a comparison of impacts among the candidate sites for the relocation of pit storage activities. Five facilities at four candidate sites were assessed for the storage of 8,000 or 20,000 pits.

For most of the environmental resources assessed in this EIS, there are no real differences in the impacts to the individual resources among the different candidate sites. This is due to the nature of the pit storage activities. The methods and procedures involved in the storage of pits have evolved and been refined at Pantex Plant to reduce the potential for impacts. This analysis assumes that the same methods and procedures would be used at each candidate site should it be chosen for pit storage. While the environments at each of the candidate sites are different, the storage methods minimize the impacts to those environments. The real differences among the candidate sites in regard to pit storage are the frequency and consequences associated with operational and external accidents.

Impacts that would result from pit storage operations at candidate sites on facilities and infrastructure, land resources, geology and soils, water resources, air quality, acoustics, biotic resources, cultural resources, socioeconomic resources, and waste management would be negligible, primarily because no new construction of facilities would be required at any of the candidate sites. Further, normal operations, including handling and storage of pits, do not require substantial amounts of utility or resource use. There would be unavoidable exposures to radiation from handling of the pits during transfer to storage. There would also be additional impacts to Pantex Plant workers from loading the pits for transfer to the storage site, if one is chosen. Likewise, there is a potential for accidents involving forklifts during unloading and storage of pits. Such accidents would affect the workers, but would not result in any health risk to the public.

The risks associated with accidents are discussed in terms of their frequency of occurrence. This EIS uses the following definitions for frequency of occurrence:

• Anticipated ùfrequency of occurrence is less than 10^-0 and greater than or equal to 10^-2 per year (less than 1 in 100 chance of occurring per year).
• Unlikely ùfrequency of occurrence is less than 10^-2 and greater than or equal to 10^-4 per year (in between 1 in 100 and 1 in a 10,000 chance of occurring per year).
• Extremely unlikely ùfrequency of occurrence is less than 10^-4 and greater than or equal to 10^-6 per year (in between 1 in 10,000 and 1 in a 1,000,000 chance of occurring per year).
• Not reasonably foreseeable ùfrequency of occurrence is less than 10^-6 per year (less than 1 in 1,000,000 chance of occurring per year).

Table 3.2-1.--Summary Comparison of Environmental Impacts at Pantex Plant (.pdf)

Table 3.2-2.--Summary Comparison of Environmental Impacts of Pit Storage Operations at Pantex Plant and Alternative Pit Storage Relocation Sites (.pdf)