SAND8.8 - 1151 Nuclear Weapon Data -- Sigma I

RS3151/88/84

Printed September 1988

Distribution Category C - 72

Final Weapon Development Report

for the W88 Warhead for the

Mk5 Reentry Body (U)

Sandia National Laboratories

Albuquerque, NM 87185

and

Los Alamos National Laboratory

Los Alamos, NM 87545

Abstract (U)

This report describes the W88 warhead that is being developed along with the Mk5 Reentry Body for use in the Trident II (D5) missile. The warhead design, its ancillary and support equipment, and the test and evaluation program are presented.

Classified by S. L. Jeffers, Supervisor, Trident II Warhead Development Division

3153, September 15, 1988.

1. W88 Overview

Design Objectives

The design objective of the W88 program is to develop a nuclear warhead for the Navy D5 Fleet Ballistic Missile (FBM), also known as the Trident II. The principal application of the D5 missile will be to provide a submarine-launched ballistic missile having a hard target kill capability by virtue of increased payload and accuracy over previous FBMs. The D5 missile capabilities are compared with previous FBM in Figure 1 [deleted].

Design Characteristics

The delivery vehicle for the W88 warhead is the Mk5 reentry body (RB), which is being specifically developed for the W88 to fulfill the hard-target kill mission. The design of the W88 allows the final weight and dimensions to be sized such that the objective of having the D5 missile deliver eight Mk5 RBs to a range of [deleted] nm will be met. The nuclear system for the W88 warhead is the Los Alamos National Laboratory (LANL) [deleted]. The overall system effectiveness is enhanced by the multi-option arming, fusing, and firing (AF&F) assembly being developed by Sandia National Laboratories Albuquerque (SNLA) in cooperation with the Lockheed Missile and Space Company (LMSC). The physical configuration of the W88/Mk5 system is shown in Figure 2 [deleted].

Exceptions

The requirements of the W88 Military Characteristics (MC) will be met with the exception of criticality under abnormal situations. This exception does not constitute a change to the requirements of the MCs. However, in the circumstances stated below the W88 warhead may not meet the requirements.

Paragraph 3.4.9 Criticality: Warhead subcriticality cannot be assured under certain combinations of abnormal situations stated in the Stockpile-to-Target Sequence (STS). This is discussed further in Chapter 4.

Criticality Safety

For any weapon to be assembled end handled safely, it must be subcritical. The W88 easily meets this criterion.

The [deleted] secondary was safely assembled and tested in the [deleted] configuration. With the large amount of neutron absorbing lithium-deuteride fusion fuel, there is no criticality concern despite the [deleted] kg of enriched uranium in the secondary.

Similarly, the [deleted] primary has been used in eight nuclear tests. One of these was a one-point safety test that demonstrated near subcriticality even in an explosive detonation.

The criticality of the W88 has been studied in some depth. Besides confirming the subcriticality in normal environments, the calculations also considered abnormal environments such as flooding and physical damage. The conclusions of these calculations are listed below.

- An unlimited number of closely packed W88 warheads remain subcritical even when totally immersed in water.

- Even with water penetration and reaction with the plutonium of the [deleted] primary, all possible arrays of W88 warheads remain subcritical.

- If any secondary is penetrated by water and leaching of the neutron-absorbing lithium hydride is [deleted].

The [deleted] secondary is protected from leaching by two seals. The first is the seal of the RB and the second is the stainless-steel membrane surrounding the secondary and interstage. Both can be breached without an explosive reaction. Of course, an explosive reaction even below full detonation would certainly destroy both seals. If a secondary is exposed to water, the reaction with lithium hydride will occur very rapidly and leaching will be accomplished in a short time. Water pressure greater than 200 psi will penetrate the first seal. The CSA will remain intact for external pressures greater than 1000 psi and will present no problem in a submerged sea water environment if no mechanical damage or corrosion has occurred. However, if the seal can is breached the secondary will become a water boiling reactor until, by heating or steam erosion, the enriched uranium is dispersed to a subcritical configuration.

Therefore, the W88 (like most other high-yield oralloy thermonuclear weapons) cannot meet the subcriticality requirement when exposed to structural damage that destroys the dual seals combined with water flooding. Because of the intended weapon use, it is important that this exception be clearly understood because it could affect postcasualty and clean-up operations.

Response [from another document, author not identified]

The Department of Energy (DoE) response for the record provided to the Senate Armed Services Committee does not adequately address the safety questions that have been raised concerning a possible criticality problem with the secondary of the W88 nuclear warhead deployed on Trident II fleet ballistic missile submarines.

First, the DoE response states that the accident scenario necessary to create the intrusion of water into the secondary of the W88 is the loss of a submarine. In fact, a handling accident could be a much more likely cause of the criticality problem. All that is required is that the seals be violated and the warhead be submersed in water. As pointed out in the many writings concerning the Drell panel's concerns, fire, explosions, projectiles, etc. may be involved during a handling accident. The canned subassembly (CSA), which houses the warhead secondary, is formed from a very thin sheet of stainless steel. Secondary designers familiar with the W88 and a similar warhead, the W87, have stated that the CSA can be easily breached with a can opener. Clearly, shrapnel from an explosion of the primary or a detonation of the Trident II third stage rocket motor could easily pierce the CSA. Perhaps exposure to heat from a propellant fire could weaken the CSA, or its joints, to the extent that submersion, even at shallow depths, could cause a seal failure. The DoE response simply does not address this more likely scenario at all.

It should be also be noted that a submarine loss is not a "most unlikely ... circumstance." The United States has lost two nuclear attack submarines curing the last 35 years. Fleet ballistic missile submarines possess no extraordinary features, absent in attack submarines, that would prevent such a loss. Also, if a submarine loss did occur, all W88 warheads aboard would experience the supercriticality. This would hardly be a manageable problem.

The statement that "The only hazard would be the radiation exposure to those personnel directly handling the unit underwater is an outrageous lie. What about the radioactive material that escapes the supercritical warhead, travels some distance, and irradiates people and animals after being ingested or inhaled. In fact, virtually all accidents with nuclear reactors cause the most damage with the radiation produced by radioactive material that has been transported and then ingested or inhaled where it can then radiate with lethal effects. Radiation emitted at the source is rarely the worst danger in an accident involving a leak of radioactive material. The material released into the environment will be a health risk to people in communities surrounding the accident location, not just "to those personnel directly handling the unit underwater."

The inadequacy of the Department of Energy response demonstrates the need for an independent panel to examine this problem and to subject its findings to outside scientific review.