Simulating Nuclear Explosions under the Comprehensive Test Ban Treaty
Top of Report
Recently Declassified Excerpts Concerning
Office of Defense Programs, February 29, 1996.
Design and Development of Nuclear Weapons
under a Comprehensive Test Ban
From the U.S. Department of Energy's
Stockpile Stewardship and Management Plan (SSMP)
a.k.a. The "Green Book"
Note to the Reader: Elements of the SSMP that appear in conflict with the CTBT's objective of constraining the development and qualitative improvement of nuclear weapons are underscored.
Stewardship and Management Program Strategy
This plan "provides for continual enhancement of the technology infrastructure and core competencies to meet national security objectives. In the future, assessments will rely on the judgment of technical personnel increasingly removed in time and experience from nuclear testing. In order to maintain and develop the expertise to sustain confidence in their judgment, substantial investments will be required to support the future stockpile stewards with advanced experimental and computational capabilities." (Preface, iv)
NRDC Comment: The continual enhancement of nuclear weapons technology infrastructure and core competencies by the U.S. and presumably other parties to the CTB, using "advanced experimental and computational capabilities," will clearly undermine the non-proliferation objectives of the Treaty by facilitating further development of nuclear weapons by both declared and undeclared nuclear weapon states.
"Areas of nuclear weapons science that are incomplete must be addressed using nonnuclear experiments in new advanced facilities. Data from experiments in these facilities, together with data from past nuclear tests, will be used to validate new or improved models in weapon simulation codes. Developing and validating these simulations will help train the next generation of scientists and engineers."(Preface, iv)
"The plan outlines 15 years of anticipated effort and is not without [technical] risk ." (p. iv)
"The limitations of the current [experimental and computational] facilities could be accepted [in the past] because underground testing was available, if necessary, to resolve specific issues….[N]ew capabilities will improve our ability to simulate the performance of nuclear weapons and serve as an attraction and training ground for the next generation of nuclear experts." (I-3)
"DOE is maintaining a surge capability to rebuild a larger stockpile." (I-3)
"In addition, some problems could necessitate redesign activities and subsequent certification. It is possible that such design, development, and certification programs could require nuclear testing, a possibility acknowledged in the President's speech of August 11, 1995. ….Changes in military requirements may lead to new design requirements, and skilled personnel must be available to execute this work." (I-4)
NRDC Comment: Executing new weapon designs in response to changes in military requirements is the very essence of what the CTB is intended to prevent! The record of the CTBT negotiations makes clear that the preamble phrase, "prevention of the proliferation of nuclear weapons in all its aspects," was commonly understood by the negotiating parties to mean prevention of further nuclear explosive device development by the established nuclear powers – so called "vertical" proliferation – and acquisition of nuclear weapons capabilities by undeclared nuclear weapon states – so called "horizontal" proliferation of nuclear weapons.
"New, improved computer-based tools, which the Accelerated Strategic Computing Initiative (ASCI) is enabling, will be essential in establishing the appropriate links between past nuclear test data and new information obtained from advanced tools such as DARHT, National Ignition Facility (NIF) ARS (X-1) and Atlas, a pulsed power facility. These tools also play a critical role in developing new analytical models to better predict the behavior of materials, components, and structures." (II-3)
"Such research will generate a large body of new technical data and is of sufficiently challenging nature that it can continue to attract and retain experienced and competent nuclear weapons scientists and engineers. Maintaining and renewing the cadre of top-caliber scientists and engineers, who understand the science and technology on which the sophisticated designs in the U.S. stockpile are based and are experts in the application of this science and technology to U.S. weapons, are a critical parallel effort to that of developing tools and models." (II-3)
"This plan provides for the continued development of such weapon components as pits, secondaries, high explosives, detonators, radiation cases, warhead electrical systems, gas reservoirs, and test and handling equipment. Specific efforts in each of these product areas will include advanced development, design, production and assembly activities. As an added benefit, these activities will exercise a significant portion of the design and development skills and processes needed to retain overall nuclear weapon competence" (II-6)
"Another essential part of maintaining the stockpile is the nearly continuous need to produce and replace tritium reservoirs, neutron generators, and other limited life components (LLCs) as their useful lives expire….and development continues on newer, more capable gas transfer systems and neutron generators for the future." (II-6)
"This plan concludes by describing a range of endeavors that will enable DOE to respond to a variety of contingencies. Included under this umbrella are efforts to preserve or enhance capabilities to: (1) initiate new weapon or component designs, if required; (2) resume underground testing, if directed by the President; (3) expand weapon or component production capacity beyond planned levels; (4) expand tritium production beyond planned levels; and (5) respond to [radiological/terrorist] emergencies." (II-7)
NRDC Comment: According to its Preamble, the CTBT is supposed to represent a contribution "to the process of nuclear disarmament." DOE's costly SSMP contingency programs for nuclear weapons design and underground testing are inconsistent with this objective.
Modifying Nuclear Weapons to Meet "Updated" Military Requirements
Under the heading "Assessment of Design Options for Refurbishment or Replacement," the DOE program plan discusses "desired modifications of weapon systems to meet updated military requirements." (IV-11)
"Refurbishment may require the design of modified or new components, …and these design changes will require assessment to validate the design methodology and to evaluate their conformance to military characteristics. The assessment of changes proposed in the refurbishment plan will require a broad spectrum of existing and new experimental, test, and computer modeling and simulation capabilities."(IV-11)
An example of such nuclear weapon "refurbishment" under the SSM Program is the "W87 Life Extension Program."
"The W87 LEP is an authorized refurbishment program to implement a set of structural enhancements to improve confidence in performance over an extended stockpile life. These improvements are designed for both the Peacekeeper environment and to support the transition to single re-entry vehicle deployment on Minuteman III. Since these modifications will affect the nuclear [explosive] package, the possible impact on physics [i.e. nuclear explosive] performance must be assessed. Hydrodynamic tests are [planned and Nova laser experiments are in progress to complement the computational modeling of these effects. In addition, the engineering efficacy of the design changes must be evaluated. Engineering functional testing includes ground and flight testing to evaluate the ability of the modified system to meet military requirements. The W87 LEP also includes a review of all components to evaluate the need for additional refurbishment action." (IV-13)
A schedule for the W87-LEP indicates that following completion of the testing program, the secondary component of the W-87 will be rebuilt in the period 1998 -2001. (Table, IV-13)
Weapon Design Options
"Weapon replacement design options that could be fielded with high confidence without additional nuclear testing will also be developed when necessary. Two candidate designs have been identified for the [Navy] Mk5 delivery system, one reusing an existing pit and one requiring new pit manufacture. These replacement designs would offer alternatives for possible replacement of existing warheads and would be prototyped, which is critical to maintaining our capability to design and fabricate new weapons as required by the Nuclear Posture Review. New experimental and computational capabilities are required to certify these designs without further nuclear testing."(IV-11)
"The goal of the Mk5 Reused Pit Option Program is to develop a replacement warhead design option for the Mk5 re-entry body that could demonstrably meet system requirements. This program will include major elements of a traditional design program, with the exception of nuclear testing. It will include a series of hydrodynamic tests as well as tests to qualify the mechanical and functional design elements. One objective of the calculation program will be the development of a methodology to ensure demonstrably large design margins in critical performance measures. The assessment plan for this program provides for continually updating and validating the computational models, hydrodynamic and other facility testing of nuclear component designs, final qualification tests of the mechanical and functional components, design reviews at periodic intervals, and a peer review of the final design [production] decision package." IV-15
"The New Pit Replacement Option design strategy will be to integrate the nuclear design, engineering design, and manufacturing capabilities in the conceptual stage. This program will also include major elements of a traditional Phase 3 design program,with the exception of nuclear testing. The new experimental facilities and computer modeling and simulation capabilities shown in [figure deleted] are necessary to assess and evaluate the expected nuclear performance. (IV-16)
Further, the future weapon manufacturing capabilities to be "developed by Advanced Development and Production Technology (ADaPT) initiative will be guided," not by the requirements for remanufacturing current weapons, but rather "by the materials, design tolerances, and material processes used for weapon replacement design."
A barchart on page IV-3 of the 1996 SSM Plan, entitled "Assessment Plan Deliverables," contains an entry for a "Mk5 Reused Pit Option" warhead with the phrase "experimental and computational assessment" describing the period 1996-2002, and "certify/prototype" entered in the columns for 2002-03. A "Mk5 New Pit Option" is scheduled for "conceptual design" in the years 1996-97, followed by "experimental and computational assessment in 1998-2004, followed by "certify/prototype" in 2005. (IV-3)
"The SLBM Warhead Protection Program (WPP) is structured to meet two primary objectives: support the current Navy strategic weapons stockpile, and provide a continuum of future replacement options. For weapons required to serve up to three times their design life (up to 60 years) the program addresses the issue that every component is a limited life component. The program is designed to support the maintenance of nuclear design expertise by:
- working on real hardware
- providing improved product to the fleet through replacement components or replacement systems
- providing alternatives to non-producible hardware (sunset technology).
The program will focus DOE effort on the protection of the SLBM deterrent by developing potential replacement options for the W76 and W88, stressing the following characteristics:
- decreased sensitivity to aging
- increased design and safety margins
- increased ability for surveillance by aboveground testing
The program is complementary to other DOE initiatives and will be coordinated with the Navy Strategic POGs [Project Officers Group] to ensure applicability to fleet needs." (II-10)
The "Green Book" also cites the need to simulate the performance of "replacement primary pits for the [existing] W88" warhead design that will be fabricated at Los Alamos National Laboratory "using different manufacturing techniques than those used at Rocky Flats Plant during the initial build." Potential replacement pits for the W87 ICBM warhead will also be "prototyped." (IV-10)
"Experiments are planned at the weapons laboratories and the Nevada Test Site (NTS) to measure changes in the dynamic response of plutonium, such as material spall and ejecta differences, that result from new welding techniques and materials processing for pit manufacturing. These experiments are essential to evaluate our capability to remanufacture pits. The improvement of theoretical modeling of material ejecta and spall and its incorporation and validation into computer simulations are required to assess the change in nuclear performance resulting from these new manufacturing techniques and materials."(IV-10)
NRDC Comment: The variations in nuclear performance introduced by changes in plutonium processing and welding techniques are already known, through previous nuclear and hydrodynamic tests, not to be of a magnitude that will significantly affect the overall reliability of the W88 warhead. Hence improved data on the dynamic response of plutonium is being gathered primarily to improve theoretical modeling of plutonium spall and ejecta" for use in nuclear weapon design codes, and not to assuage plausible reliability or safety concerns.
Maintaining Capabilities For Nuclear Weapons Design, Engineering, and Underground Testing
Under the chapter heading "Maintaining the Stockpile," the report notes:
"Weapon refurbishments to extend service life and correct faults detected by surveillance require the same spectrum of design, development, and production activities previously required for producing new weapons, but now these capabilities will be focused on sustaining the existing stockpile. (V-1)
Among several "essential program needs," the plan lists "design and development capability, " and describes planned activities that will "provide and demonstrate the capability to design and develop nuclear weapons and associated components (emphasis added)" (V-3)
A subsection entitled "Design and Development Capability" describes activities in "System Engineering and System Design," "Integrated Nuclear Package" design, "nonnuclear Subsystems and Components," "Systems Integration and Test," and "Test and Handling Equipment." (V-9 through 14).
"Redesigning weapon components to meet requirements for existing Alts, Mods, and SIPs [Stockpile Improvement Programs) will exercise many of the critical design skills for developing new or replacement weapons, should that contingency be required at a later date. However, to ensure that all critical skills are maintained, advanced development activities will focus on exploring and developing potential options for refurbishing and replacing weapons in the future." (V-8)
"Status. Many critical design skills are being maintained through current programmed refurbishment activities of several weapon systems – including the B61, B83, and the W87 – and through advanced development activities such as the Warhead Protection Program, a cooperative program with the strategic Navy." (V-8)
"System engineering and system design activities are essential elements of ensuring that refurbished weapons meet DoD requirements (e.g. military characteristics and Stockpile to Target Sequence), consistent with available technology and resource capabilities within DOE. DOE will work with DoD in reviewing DoD requirements to ensure that weapon designs generated in the 1970s and 1980s continue to support national security requirements during the weapons' extended lifetime. DoD [i.e. military] requirements drive the tradeoff analyses that lead to the selection of refurbishment design approaches for weapon system and subsystem options. Subsystem and component design constraints and requirements will be developed when the system design approaches are selected. This process will require close coordination between DOE and DoD." (V-9)
The report notes that "many essential system engineering and system design skills are being maintained through such advanced development activities as Advanced Electrical Architectures Studies, the Warhead Protection Program with the Navy, and life extension of the B61-3, 4, and 10." (V-9)
Nuclear Package Design
Under the heading "Integrated Nuclear Package," the report observes, "The skills required to conduct the full range of assessment and certification activities [detailed in Chapter IV of the report] are common to nuclear package design. The programs include, but are not limited to, detailed computational and experimental assessments of all stockpile nuclear systems (e.g. hydrotesting, HE evaluation, gap analysis, spall/ejecta, aging evaluation, new design evaluation, dynamic material properties, gas cavity studies, fission ignition and burn, and radiation transport). These efforts provide a focus for the maintenance of nuclear design capability."
"The laboratories are currently working on programs to provide new or modified designs that will address current stockpile issues and will exercise a broad range of design skills.
These programs include the following:
"B61-11 replacement for the B53 gravity bomb. The B61-7 will be modified to replace the B53. This modification will provide enhanced surety [i.e. safety and use control] features relative to the B53. The design and engineering development of the B61-11 will require hydrodynamic testing and engineering functional testing that supports nuclear design capability.
"W87 Life Extension Program. The W87 life extension program will require a program of design and evaluation for the physics package, including the assessment required for certification.
"B61 Mod 3, 4, and 10 surety upgrades. Proposed modifications to improve the safety of the weapon will require an active nuclear design and laboratory test program to support final evaluation and nuclear certification.
"In addition to the above programs, which are expected to lead directly to stockpile modifications, the nuclear weapons laboratories will conduct prototype programs to provide possible future replacement warhead designs for Navy and Air Force systems. The initial focus for design activities will be the SLBM Warhead Protection Program, a program which is being coordinated among the Navy SSPO [Strategic Systems Program Office] , DOE, and the weapons laboratories (V-9)
"Two candidate replacement nuclear designs have been identified in this [SLBM Warhead Protection] program. One design would require new pit fabrication, thereby maintaining expertise in new pit technologies. The other would incorporate a reused pit from a retired warhead, providing design and development experience in pit reuse technologies. Reuse of pit in new primaries has been demonstrated with successful nuclear tests of several designs that also incorporate fire resistant shells and insensitive high explosive [the W88 warhead currently has neither]. Pit reuse offers the possibility of manufacturing new primaries at reduced cost without requiring an expansion of currently planned Pu [plutonium]fabrication facilities (V-10)
NRDC Comment: "Pit reuse" is much to be preferred over "new pit fabrication" from both an environmental and cost perspective. It has significant diplomatic advantages as well, as one of the key features that distinguishes a "new type" of nuclear weapon from a "modified" or "remanufactured" one is the fabrication of new-design nuclear components (there is little justification for refabricating existing nuclear components if a sufficient inventory exists, and the U.S. currently plans to retain a total inventory sufficient for some 15,000 weapons). Existing U.S. nuclear components have indeterminate lifetimes, estimated to be a minimum 50 years for primary plutonium pit components and longer for uranium-lithium secondary components.
"The technical approach for the new design candidate warhead is to use large design margins for critical components; warheads would be certifiable without nuclear testing. This design process will use concurrent engineering methods to help define future manufacturing techniques by selecting materials and defining tolerances consistent with future capabilities. Both of the replacement design options will be prototyped and flight tested, but no final development activities will be initiated until a decision is made to proceed. The nuclear design activities of this program will be broadly basedand will provide present and future weapons scientists and engineers with the opportunity to exercise the complete set of skills required to design and develop a stockpile warhead." (V-10.)
Systems Integration and Test
Under the subheading "Systems Integration and Test," the program plan notes that this category "covers the full spectrum of design activities to ensure that individual subsystem designs have been successfully integrated into a nuclear weapon system and certified for reliable operation throughout the required Stockpile-to-Target Sequence environments (e.g. acceleration, vibration, thermal, and radiation). In this context, systems test also includes the design of Joint Test Assemblies (JTAs), support of system and flight tests, and provision of any special fixtures and testers required during development, certification, and surveillance testing. Integration and systems test also include the activities associated with the test and certification of DOE/DoD weapon system interfaces." (V-12)
"Current facilities, such as the system test facilities at Tonopah, Nevada; Kauai, Hawaii; and Sandia's extensive environment test facilities (including vibration, shock, centrifuge, high speed sled track, fire facility, and lightning facility), must be sustained to support future requirements ….Current Sandia radiation and test certification facilities…will also be required to support the W62, W76, W78,W87, and W88 programs. The development of future pulsed power sources (PBFA-Z, ARS(X-1) and Jupiter) that significantly enhance radiation sciences and weapon physics testing capabilities are required to replace underground nuclear effects experiments for simulations of hostile radiation environments….High fidelity, validated [computer] certification models must be developed to replace lost test capabilities and supplant those tests that are not economically viable." (V-13)
"The nuclear design capability will be maintained by pursuing an understanding of the underlying physics of nuclear weapons and exercising the process of design of nuclear weapons. This includes material properties, hydrodynamics, radiation transport, and neutron transport as well as many other physical processes that occur in the operation of a nuclear weapon. Advanced computational capabilities will be required to adequately address concerns if the design laboratories are forced to deviate from designs that have been verified through nuclear testing. Additionally, to support this effort experimentally, several new facilities are proposed, as described in [other still classified sections of the report]. The combination of new basic physics understanding, new computational capability, and new nonnuclear experimental capabilities will support continued confidence in DOE's judgment on matters of nuclear design." (VII-3)
"The ability to design nuclear weapons is the core of [the] DOE program and is utilized in all other aspects of the program. There are new constraints on the nuclear weapon design laboratories that have changed the approach. First, the laboratories are no longer actively pursuing new design paths. That is, there are no new military requirements at this time (emphasis added). Second, one of the most important tools used by the nuclear design laboratories, underground nuclear testing, is no longer available. Finally, the nuclear weapon design laboratories are prohibited by legislation and policy from pursuing some design paths. The combination of these factors has raised concerns regarding the future ability to respond to new design requirements or constraints in component production."(VII-3)
NRDC Comment: Read in conjunction with the rest of the excerpts cited in this report, the preceding paragraph provides some insights into the U.S. government's approach – both substantive and rhetorical – to the CTB objective of "constraining the development and qualitative improvement of nuclear weapons and ending the development of advanced new types of nuclear weapons (emphasis added)."
*First, as the "Green Book" makes abundantly clear, the U.S. government does not subscribe to the view that the test ban should or will constrain "qualitative improvement" of nuclear weapons when these improvements take the form of new-design non-nuclear components, or modifications to the nuclear components of already explosively tested designs, even if such modifications previously "required" certification by underground nuclear tests, or constitute a new or improved military capability.
*Second, the U.S. government clearly intends to maintain under the CTBT, and indeed significantly enhance, its scientific and technical capabilities for undertaking "development of advanced new types of nuclear weapons."
*Third, the Department of Energy and the Strategic Systems Program Office of the Navy are already embarked on a program to design, develop, prototype, and flight test an indisputably new-design warhead for the Trident II missile to replace the current W76 and W88 warheads. There is as yet no "military requirement" to produce this weapon design for the stockpile. While little is known of the characteristics of this new warhead, Department of Energy denials that this warhead constitutes an "advanced new type" of nuclear weapon are most probably correct.
*Fourth, from a technical nonproliferation perspective, the SSMP's heavy emphasis on expanding the base of fundamental (and therefore largely unclassified) physics knowledge applicable to development of accurate computational simulations of nuclear weapons performance, will severely undermine the treaty's objective "to contribute effectively to the prevention of the proliferation of nuclear weapons in all its aspects."
"A limited number of new nuclear component design requirements are foreseeable in the future….Nonnuclear system design capability can be updated through exploratory design projects." (VII-3)
Underground Test Readiness
"The approach described in this document seeks to achieve nuclear test readiness in a cost-effective manner by conducting a DOE/DP experimental program that provides necessary data for the stockpile and, in addition, effectively exercises worker skills to maintain readiness to resume nuclear testing….Unique capabilities of the Nevada Test Site (NTS) will be utilized to conduct experiments requiring large quantities of high explosive (HE). Other experiments involve special nuclear materials (SNM) driven by HE. Although the principal purpose of these experiments is to provide data for nuclear design laboratory programs, their execution will be very important to an ongoing test readiness posture.
Those few capabilities essential for nuclear testing [that are] not used during the experimental program will be exercised periodically to maintain relevant skill bases."(VII-4)
NRDC Comment: More a product of pork barrel politics than reasoned analysis, a program premised on maintaining readiness to "break out" of the CTBT is a deep diplomatic embarrassment to the United States, complicates verification of the treaty, and stands as an ugly emblem of U.S. distrust of the international community and of our seemingly incurable addiction to nuclear weapons.
"The NTS experiments depend on ongoing research in hydrodiagnostic measurement technologies for experiments at nuclear design facilities. Development will be required to integrate new technologies with the underground environment for the SNM experiments, where remote control and monitoring will be necessary." (VII-5)
"The [NTS] experiments are designed to contribute to the validation of laboratory weapons design and analysis codes currently in use and being developed under the ASCI program."(VII-6)
The Department of Energy Plans to Continue Making Weapon Modifications that Formerly Required "Certification" by Nuclear Explosive Tests
"The term certification refers to a formal process by which the cognizant design laboratories confirm that a warhead or component design conforms to its required military characteristics, with exceptions noted. Certification has historically been associated with the introduction of new warheads into the stockpile. When a weapon is introduced into the stockpile, the responsible weapons laboratory directors sign the Final Warhead Development Report, which is provided to DoD. DoD's Design Review and Acceptance Group (DRAAG) uses this document as the foundation for its independent assessment of the ability of the weapon to meet military requirements. A positive assessment of the DRAAG is the basis for DoD acceptance of the warhead." (IV-22)
"The second document is the Major Assembly Release. This document, prepared by Sandia National Laboratories and approved by both responsible weapons laboratories and then DOE, states that specific war-reserve material is satisfactory for release to DoD on a designated effective date for specified uses that are qualified by exceptions and limitations. To add confidence to the DOE certification process, agreements have been developed within DOE to deal with the lack of full yield testing of weapons with yields greater than 150 kilotons. These agreements added[ed] a peer review process by a second laboratory team." (IV-22 and 23)
"No new or substantially modified nuclear weapons have entered the stockpile since U.S. nuclear testing ended in September 1992. In the near future, however, several modifications to existing weapons are planned, and they will require certification prior to deployment. These include the B61-11 replacement for the B53, W87 refurbishment, and the replacements for the destructively tested surveillance units of the W88, which will use pits fabricated with a different process than those in the current stockpile. In addition, future replacements to nonnuclear components will generally employ modified designs. DOE's existing certification process with its peer review agreements provides a framework for these actions."(IV-23)
"An additional aspect of certification was introduced by President Clinton in a speech on August 11, 1995, in which he directed the establishment of a new annual reporting and certification requirement, which will affirm that our nuclear weapons remain safe and reliable under a comprehensive test ban, or identify significant issues that could lead to the need for a nuclear test." (IV-23)
"During FY 1996, new certification procedures for stockpiled warheads must be developed in response to the Presidential reporting requirement. Preliminary discussions have begun between DOE, DoD, and the National Security Council. With regard to the certification of new designs for the stockpile, existing agreements calling for peer review as part of the DOE certification process are adequate, but a requirement exists to provide sufficient documentation to satisfy DRAAG requirements. Additional work is needed to define the level of modification to a current design that should initiate a formal, peer reviewed assessment." IV-23
NRDC Comment: Apparently the U.S. government itself does not yet know when a "substantial modification" to a current design becomes a "new design" requiring a formal peer review by both weapons laboratories and formal review and acceptance by the Pentagon's Design Review and Acceptance Group. What is important to note is that the U.S. government is contemplating both types of certification procedures under the CTBT.
DOE/DoD Plan Joint Flight Testing of Modified and New Weapons under the CTBT to Certify Their Military Mission Capability
"Joint Flight Testing. Joint flight testing demonstrates the compatibility between DOE and DoD subsystems and verifies weapon systems function…. In July 1992 DOE issues a Joint Test Assembly (JTA) design directive. The primary purpose of the directive was to develop an overall philosophy to optimize performance features and address [warhead] environmental [stress] issues on a consistent basis. "The current JTA design philosophy maintains operational system similarity and identifies problems that are inherent in the design of the warhead or attributable to: the employment of the warhead as part to the weapon delivery system; the warhead aging process; or assembly techniques or procedures. Addressing these issues generally requires multiple [JTA] designs.
"Included in the JTA design directive is the concept of high fidelity JTAs. High fidelity JTAs are designed to more realistically resemble a nuclear weapon (e.g. high explosives with a mock pit). However, these types of JTAs do not contain any tritium-filled reservoirs and usually do not contain any special nuclear material. DOE is currently developing a five-year implementation plan for new JTAs, that will be more in compliance with the design directive." (III-6 and 7)
"Two new types of JTAs can augment the existing flight test program. The first is a high fidelity configuration; the second is a highly telemetered JTA that displaces only small parts of the nuclear package.
"High fidelity units are built to simulate the most realistic warhead where the basic change to the War Reserve configuration is replacement of special nuclear materials with surrogates. These units have no onboard telemetry. All functions are exercised and the expected outcome is a high explosive detonation over target. Ongoing R&D allows some off board diagnosis of the flight test and affords a limited understanding of the quality of the implosion, with more [R&D] planned.
"A new generation telemetry-based JTA is also being envisioned that will use technology advances to miniaturize the electronics. Modern technology will allow us to design a telemetry package that will fit into the secondary volume of the weapon, leaving a high fidelity denuclearized primary as a component to be tested in flight, or vice versa. In addition to measuring the relatively slow data obtained from current JTAs (e.g. acceleration, strain, temperature, voltage) this package will record the high-rate data. These data are important to the nuclear designers in scoring the implosion. This test might be characterized as a flying hydrotest." (III-12)
The U.S. Plans New Experimental and Computing Facilities to Improve Nuclear Weapon Physics Models and Nuclear Explosion Simulation Codes
"The end of underground testing will necessitate fundamental changes in the stockpile assessment and certification process. Aboveground experimental facilities that once supplemented underground nuclear testing must be expanded to provide more comprehensive data across a broader range of nuclear processes. Computational modeling, once a tool to facilitate design and evaluation, must now serve as the integrating factor to link aboveground experiments, historical nuclear test data, and design experience into a nuclear predictive simulation capability."IV-2
"Experimental programs involving a broad range of existing and advanced facilities will develop the data needed to understand nuclear weapons science at a level more fundamental than was required in the past. The conditions, energies, and densities in the appropriate materials found in many aspects of a nuclear explosion cannot be achieved in the laboratory over the range of needed time or physical scales. Therefore, new experimental facilities – each having the capability to probe different subsets of these conditions – must be developed. Highly accurate computational simulations of weapons systems will integrate this fundamental understanding, apply it to stockpile issues, and tie it make to experiments and past nuclear tests. The experimental and computational assessment programs must also support the continuing need to evaluate intrinsic and external radiation effects…." IV-2
"Consistent physical models will be developed representing the essential processes from detonation through the secondary nuclear explosion. These models will be experimentally validated in our research program using new and existing facilities."(IV-6)
"The model validation effort cannot be executed without the high quality experimental data that will be provided by new facilities, especially to address implosion hydrodynamics and high-energy density phenomena. To meet these requirements, investments are being made in new facilities such as the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility, an Advanced Hydrotest Facility (AHF), the National Ignition Facility (NIF), and Advanced Radiation Source (X-1) and the Atlas pulsed power facility."(IV-4)
"Investments are also being made in supercomputing through the Accelerated Strategic Computing Initiative (ASCI). High-performance computing far beyond our current level must be developed to run the simulations. The shift to computation-based methodologies for assessment and certification will require large improvements in the laboratories' core computational capabilities. ASCI will develop the applications, high performance computers, and problem-solving technologies to feed this core program." The report specifically notes that DOE's warhead "assessment" program is "designed to address [inter alia] …the viability of design options for refurbishing or replacing specific warhead systems. " (IV-4)
"Assessments will ultimately rely on the judgments of scientists and engineers who will be further and further removed in time from nuclear testing and new weapons development experience. A cadre of highly skilled scientists and engineers must be continually attracted to the nuclear weapons program and developed through the assessment program. A broad spectrum of skills is critical to address the challenging problems that will arise with the aging stockpile. Substantial advances in experimental and computational capabilities are needed to maintain and develop their expertise and sustain confidence in their judgments." IV-2
"Computer modeling and simulation improvements are currently being implemented and validated in two-dimensional radiation hydrodynamic and explosion codes. In order to completely assess the nuclear performance of the weapons, designers will require computer modeling and simulation improvements in three dimensions."IV-10.
NRDC Comment: Rather than relying on a costly, technologically complex, politically provocative, and ultimately uncertain program to reproduce capabilities for exercising "designer judgement" in future generations of weapons laboratory personnel, NRDC believes that DOE should use its waning asset of test qualified personnel to certify the specifications for "standardized," indefinitely producible configurations of a limited set of current stockpile designs, specifications that would then be rigorously adhered to, to the maximum achievable extent, in order to minimize future changes to, and performance uncertainties in, a future stockpile of perhaps a few hundred weapons. Under this approach, a new generation of nuclear "designers" relying on "substantial advances in experimental and computational capabilities" would not be needed, as minor uncertainties in calculated nuclear performance would be tolerated, and major uncertainties (arising from material degradation, for example) would be dealt with through periodic remanufacture of existing component and subsystem designs, and if necessary, entire warhead systems.
Under the subheading "Material and Component Modeling and Analysis," the "Green Book" discusses a number of initiatives, including:
"Improving and benchmarking computations and simulations. The purpose of this effort is to develop a comprehensive model of the nuclear physics package for each weapons type. This model will begin with the original design and will employ advances in computational power and codes. The numerical simulation will be correlated with aboveground and underground test data.
"Predicting surveillance hydrotests. After baseline models are developed, they will be used to predict hydrotests of stockpile return assemblies.
Predicting High Fidelity flight tests. A structural/dynamic model will also be built for each weapon. This model, in conjunction with the hydrodynamic and nuclear physics models, will be used to evaluate the adequacy of the weapon assemblies against the stockpile storage and delivery conditions, as defined in the STS [Stockpile-to-Target Sequence]. Examples of data that will be used in understanding the nuclear performance in flight are detonator simultaneity, implosions or explosion characteristics, and gas system performance (up to and including tritium delivery)."(III-10)
DOE Seeks Improved Fundamental Understanding of Weapon Physics to Create Comprehensive 3-D Models of Nuclear Weapon Explosions
Under the Heading "Fundamental Science in Weapon Modeling and Assessment," the report states:
"The existing empirically based models implemented in our current simulation codes were partially validated through nuclear testing and supporting experiments. However, there are many outstanding issues of fundamental understanding in nuclear weapon science, associated with each stage of weapon operation, that must now be addressed to develop a sufficient basis for weapon assessment and prediction of changes without additional nuclear testing." (IV-24)
"These issues have been prioritized according to the best current evaluation of needs and abilities, and are being addressed systematically. Theoretical models for specific phenomena are being developed and simulated in stand-alone codes. Often they address technical areas, such as instabilities and turbulence, which are not yet formally understood by the general scientific community. New scientific data must be obtained to guide the theoretical development and validation of these models, requiring new experimental capabilities. When validated, the models must then be put into a form that is accurate and efficient for use in our weapon simulation codes. (IV-24)
Predicting Primary Stage Performance
"Direct functional testing can still be performed for most nonnuclear [explosive] weapon system components ….Absent additional nuclear testing, improved models benchmarked against simulation data and validated against data from previous nuclear tests will be the principal basis for assessing the adequacy of electronic and other nonnuclear component behavior in radiation environments." (IV-24)
"A variety of high-explosive driven hydrodynamic experiments using advanced diagnostic capabilities, including high-resolution radiography at multiple times with multiple views, are essential to define the implosion characteristics in the preboost phase or in a safety scenario. Improved theoretical models related to dynamic materials behavior, and fundamental data on particular materials such as high explosives and plutonium, will be essential for adequate modeling and assessment."(IV-26
"Improved understanding and data related to the dynamic behavior of materials, including age-related changes, will be studied with well-diagnosed experiments using explosive projectile guns, pulsed-power, and lasers. Studies must include understanding of real materials and alloys in manufactured components. Materials science laboratories and tools such as lasers, synchrotron radiation sources, and the application of powerful neutron sources such as LANSCE, will provide much of this important information." (IV-26)
Predicting Late Primary Stage Performance
"The other key technical issues associated with primaries involve the ignition and burn of their boost gas, which are extremely difficult to access experimentally without nuclear testing. Laser and other inertial confinement fusion approaches, and pulsed power experiments may be able to provide an improved understanding of the aspects [sic] of gas burn physics. The data gathered in this complete set of experiments will be essential for evaluating new and evolving computational models of the primary stage behavior."(IV-26)
"The later phases of operation of a primary stage (fission explosion and fusion ignition and burn) rely heavily, in the near term, on physically based advanced computer modeling and simulation and reanalysis of past nuclear test results. As advanced hydrodynamic capabilities like DARHT (and, in the longer term, AHF) become available, they will provide a significant experimental capability to be added to the assessment of primary operation. Pulsed-power, NIF, and other non-laser driven fusion approaches, may be used to provide broader experimental validation of the aspects [sic] of the late phases of primary operation in computer modeling and simulation."
"Radiography is an especially important diagnostic for probing performance of primaries at 'nuclear' times. Current facilities at FXR [["Flash X-Ray Facility," Livermore Site 300] and PHERMEX ["Pulsed High Energy Radiographic Machine Emitting X-Rays," Los Alamos] do not have adequate resolution to probe the primary stages in the current stockpile [i.e. in their most densely imploded configurations]. The capability of hydrotest facilities will be improved through upgrades (e.g. FXR and Phermex double pulsing), the addition of diagnostics (e.g. the gamma ray camera), and facility improvements (e.g. Contained Firing Facility). DARHT will provide an expanded hydrotest capability to address both 3D issues and time dependence through the use of two radiographic machines. (IV-29)
"DARHT will have improved resolution that will allow safety and performance assessments for most stockpile primaries. The AHF will be a subsequent development with multiple axes and multiple times to address performance and safety issues that require a high level of accuracy on the 3-D [three-dimensional] density distribution of materials at nuclear time. New radiographic techniques that do not utilize gamma rays, such as proton radiography, may be necessary to provide this capability." (IV-29)
Predicting Secondary Stage Performance
"However, the high energy-density conditions relevant to secondary performance are extremely difficult to create in a laboratory setting, and most data must be extrapolated to the weapons regime in at least some parameters, requiring the expert judgment of weapons scientists following a careful strategy of fundamental science, scaled experiments, and comparison with past nuclear test data to validate models….laser and pulsed power experiments, as well as computer and simulation modeling advances, are critical to obtaining fundamental physics data that when validated with past nuclear test data, can be used to assess the full nuclear performance of the secondary stage."(IV-27)
"The [computational physics] model validation effort cannot be executed without investment in new experimental measurement capabilities and facilities, especially to address implosion hydrodynamics and high-energy density phenomena. Facilities are also required to provide weapons effects information previously obtained in DNA-sponsored nuclear tests.(IV-27)
"Experimental study of the thermonuclear phase of a weapon explosion is necessary to improve our understanding of the nuclear test database, to evaluate issues identified by stockpile surveillance [e.g. effect of materials degradation on nuclear performance], and to validate new computational modeling and simulation. This work requires experimental facilities that can create hot dense plasmas approaching the physical conditions important to secondaries and some aspects of primary operation.
"Both laser and (electrical and high explosively driven) pulsed-power sources can drive hydrodynamic implosions of experimental targets or assemblies, and heat targets for radiation physics experiments; these technologies are complementary in providing the needed capabilities. High-energy lasers provide the highest temperatures and pressures available in the laboratory, in few-millimeter experimental volumes for several billionths of a second. Pulsed-power sources provide high total energy to larger volumes of material (centimeter scale) for longer times, though at lower temperatures and pressures." (IV-29)
"Understanding the properties of plutonium is essential to the accurate modeling of the performance of a primary. Experiments are currently being initiated in the Lyner complex at NTS to experimentally measure the high-pressure equation of state (EOS), strength properties, and response to shock of plutonium. Energy drivers will include high explosives, pulsed power, and gas guns at the NTS and the laboratories. A detailed understanding of plutonium material properties will require the application of a variety of state-of-the-art diagnostics (e.g. velocimetry, holography, laser-illuminated high-speed photography, x-ray radiography, and [shorting] pins) as well as diagnostics developed specifically for these experiments. Some plutonium experiments are compatible with above-ground facility capabilities (e.g. diamond anvil, laboratory gas guns, and laser-driven flyer [plate] EOS studies0, and can take advantage of additional diagnostic capabilities (e.g. synchrotron radiation sources).
"Dynamic experiments are conducted to understand high explosive (HE) properties, primary and reflected shock structure, and material response, and to examine the effects of engineering features such as welds and surface finish on probable weapon performance. In addition, experiments are conducted to measure the integral performance of complete weapon assemblies to validate models subject to uncertainties from incomplete physics, uncertainties in material properties, computational symmetry assumptions, and the effects of calculations using discrete elements. Hydrotesting of primaries is the only remaining way to test the integral performance of a primary in real weapon geometries." (IV-29)
Enlisting the Help of the University Research Community
"To ensure that the foremost judgment and capabilities are available for assessing the safety, security, and reliability of the stockpile, it will be important to extend our collaborative programs with universities and industry. These collaborations will further enhance the science and technology base that can be used for U.S. nuclear defense needs. Strong collaborations with universities will help form a cadre of young scientists trained in defense-related capabilities. Additionally, these collaborative programs, through teaming, competition, and peer review, will fine tune the skills of the personnel conducting the assessment of the stockpile. To address the needs of the stockpile, the foremost science and technology in the world will be utilized." (IV-31)
NRDC Comment: On July 31, 1997, DOE announced a program to provide $250 million program over ten years to fund computer-modeling research centers at five universities – the California Institute of Technology, Stanford University, the University of Chicago, the University of Utah, and the University of Illinois at Champaign-Urbana. The program will also provide researchers at these centers with about 10% of the run time on current and next generation supercomputers at the three DOE nuclear weapon laboratories. According to the Washington Post, each university will work on a separate unclassified topic "that happens to be related to weapons issues." The University of Chicago will emphasize fusion physics "to finally understand in quantitative detail how massive stars explode." Caltech's center will concentrate on shock-wave phenomena, and Stanford's will study fluid dynamics and turbulence. Utah will focus on models of accidental fires and explosions, and Illinois on simulation of advanced rockets.
On a more philosophical plane, it should be noted that the "needs of the stockpile" are not self-evident or self-defining, but are rather susceptible to a rather wide range of formulations, the more sober and sensible of which do not require "the foremost science and technology in the world" to be utilized.
Improved Computations for Weapons Simulations The Accelerated Strategic Computing Initiative (ASCI)
- "The ASCI program plan has four main objectives:
- a. Performance: Create highly credible virtual tests to analyze the performance and predict the behavior of nuclear weapons;
- b. Safety: Predict with high certainty the behavior of weapon systems in complex accident scenarios;
- c. Reliability: Achieve sufficient validated predictive capabilities to extend the lifetime of the stockpile, predict failure mechanisms, and reduce routine maintenance;
- d. Renewal: Use virtual prototyping [i.e. 3-D "solid" modeling of weapon components] to reduce the need for testing and production facilities required for stockpile requalification and replacement work." (Appendix B-1)
- b. Safety: Predict with high certainty the behavior of weapon systems in complex accident scenarios;
NRDC Comment: With nuclear weapons no longer on airborne or strip alert, or deployed with tactical forces in the field, the likelihood and thus need for analysis of "complex" accident scenarios is much reduced. Moreover, it is not necessary to predict when aged materials will ultimately lead to weapon failure, but merely to surveil weapons for signs of deterioration and replace aged components on a timetable dictated by prudence rather than the technical challenge of "predictive capability."
The ASCI "will create the technology to address weapons problems through advanced computational simulation." (IV-31)
"The core computing program is the foundation program that ASCI is designed to enhance. The core program provides computers, storage systems, digital communications, and computational models to address stockpile issues. It maintains and improves the current [nuclear-test] validated codes and adapts them to run on more capable machines as they become available.
The current codes are essential elements of our current stockpile assessment and certification process. However, these codes and their current rate of improvement are not sufficient in the absence of nuclear testing [sufficient for what?]. Under ASCI, appropriate new or improved physics models and algorithms appropriate to scaleable HPC [High Performance Computing] architectures will be developed and incorporated into the codes in order to enhance their predictive capabilities." (IV-31)
"ASCI is envisioned to shift promptly from nuclear test-based assessment methods to computational-based assessment methods. The ASCI program was developed as a surge capability to provide the required dramatic advances in computer hardware and predictive, physics-based modeling and simulation computational tools." ASCI "will extend DOE's computational resources to create an assessment program that does not rely on additional nuclear testing and prototyping capabilities for nuclear weapons."
ASCI will focus on "developing high performance, full-physics, full system, 3-dimensional (3-D) predictive codes to support weapons designs, production analyses, accident analyses, and certifications. Applications in weapons physics,] engineering, and manufacturing science will be the main focus of the applications code development effort. Together they will provide the ability to predict the performance of full nuclear weapon systems…" (IV-32)
"Existing codes, constrained to run on current computers, do not have the physics models necessary to accurately simulate the processes and phenomena needed for virtual testing and prototyping. For example, existing codes have several empirical factors that the user must set. These settings are not based on physical understanding of the phenomena in question, but on the judgment of the experienced user in matching past experiments. These empirical factors severely restrict the predictive capability of our codes.
"Removing empirically based factors from the application codes requires an understanding of the physics that the empiricism currently replaces, and requires the creation of new models in the codes to simulate the physics. These new models will have to be verified and validated using different methods and techniques.
For example, in the absence of underground testing, the new physics models in the [nuclear explosive] device analysis codes must be validated using advanced aboveground experiments (AGEX) facilities and past underground test data. Similarly, accurate virtual prototyping methods must be developed …"
"The increasing computational power that ASCI will provide will enable calculations of thermomechanical properties, opacity (i.e. a measure of a materials capacity to absorb radiation), and material microstructure that are well beyond our current computational capabilities. These types of materials calculations are important contributions to improved understanding of weapons performance and aging. They also enable the prediction of microscopic material characteristics generated by various manufacturing processes that must be understood, modeled correctly, and controlled if future replacement [nuclear] components are to be certified." (Appendix B-3)
30. The program plan is misleading on this point, as some planned experiments are "non-nuclear," while other are not. Many planned experiments involve the use of nuclear explosive materials – plutonium, uranium, and heavy hydrogen – and some of these, if successful, will involve actual micro-fusion explosions driven by high energy lasers, electrical pulse-power machines, high-explosive magnetic flux generators, or high-explosive implosion devices.
31. This speech established the maintenance of nuclear weapons reliability as a "supreme national interest" meriting possible withdrawal from the CTBT.
32. For example, the Furse Amendment of 1993 bars the engineering development and/or production of new nuclear explosives with yields less than 5 kilotons. Similarly, established policy directs that the Strategic Defense Initiative develop non-nuclear antimissile systems, and bars the production or deployment of enhanced radiation (neutron) weapons.
33. Washington Post, "Colleges Get Access to DOE Computers; Schools Will Study Nuclear Stockpile," August 1, 1997, page A19.
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