When Congress decided to stop funding research on the Robust Nuclear Earth Penetrator (RNEP), the opponents of the program cheered. However, the very same bill that cut RNEP funding allocated funds to the Reliable Replacement Warhead (RRW) Program. Those who objected to RNEP should pay close attention to RRW, which is currently in a study phase, to ensure that the same problems they saw in RNEP do not sneak by as part of the RRW. RNEP was difficult to design and justify given the moratorium on nuclear testing and new weapons development - two issues that also need to be watched for in RRW. 

In 2003, Congress allocated funds for the National Nuclear Security Administration (NNSA) to conduct a feasibility study of the RNEP. The 2002 Nuclear Posture Review identified as a strategic threat the proliferation of Hardened and Deeply Buried Targets (HDBTs) such as bunkers. The idea behind the RNEP was to create a nuclear weapon that could hit these targets. Ideally, it would be designed to penetrate the earth to a depth significant enough to destroy hidden targets while minimizing collateral damage from the explosion. Tests have shown that compared to surface detonations, earth penetrating bombs or ‘bunker busters’ have greater impact on hidden targets by transmuting and amplifying their explosive power through the ground. However, it is impossible to contain the explosion underground and massive clouds of radioactive dust would be created.

The proposed study of the RNEP included modifying two existing nuclear weapons to allow them to hit buried targets—the B61 (which is already the basis for the B61-11 earth penetrator), but also the B83 air-dropped bomb. The B61-11 had been designed by encasing the Nuclear Explosive Package (NEP) from an earlier bomb design in hardened steel with a new nose cone in the hopes of improved ground penetration capability. Tests carried out prior to the 1992 moratorium on nuclear testing show that the B61-11 can only effectively penetrate two to three meters in frozen soil. Despite the evidence of the extensive reengineering required to make the B61-11 warhead, the weapon was claimed to be the result of “modifying” existing designs rather than the “creation” of a new weapon.

Leaving aside the problems of accurate targeting and faulty intelligence in selecting targets, extensive logistical difficulties exist in meeting the twin goals of target destruction and minimal collateral damage as stated in the RNEP plan of study. Earth Penetration (EP) weapons cause greater fallout compared to an air explosion because they lift a greater volume of earth. EP design also has to ensure that the warhead and electronics are protected and do not melt under the high velocity impact. Even the very hardest casing severely limits the missile penetration depth and therefore increasing the yield would appear to offer a better chance of destroying the HDBT. Additionally, the deceleration force of the weapon would need the non-nuclear components to be extensively redesigned. Without nuclear testing, this process is expensive and even then, the possibility of nuclear testing could not be ruled out. If the United States were to break its 1992 moratorium on nuclear testing, other countries would soon follow suit. 

Funding for the RNEP study had initially been projected at $15 million annually from 2003 to 2005 but was reduced to $7.5 million in FY 2004 in response to objections from various members of Congress regarding its scope. In the FY 2005 budget cycle, NNSA handed Congress a proposed aggregated five-year budget of $484.7 million. But the activities detailed in the budget included forecasted development of a weapon, pending of course Congress’ approval, and concerns were voiced about whether funds were being effectively used if new weapons were being developed instead of reducing the nuclear stockpile. Rep. David Hobson, R-Ohio, head of the House Energy and Water Development Subcommittee, instead pushed for giving funds to the Reliable Replacement Warhead (RRW) Program, viewing this as a more focused and less controversial use of funds. The initial demand for RRW funding for FY 2006 had been $9.4 million but the House and Senate pushed this figure up to $25 million. RNEP funding was stopped although the Pentagon was allocated $4 million to conduct a conventional penetrator “sled test.”

The RRW program is currently a congressionally mandated study to examine the feasibility of manufacturing and certifying new nuclear warheads keeping in mind current strategic and technical concerns. In statements before the House Energy and Water Development Subcommittee, the NNSA has presented RRW as a flexible and sustainable long-term response to the nuclear stockpile that would include reducing its size, lower risks of technical failure, lower manufacturing costs, lengthening its life span and increase the ease of manufacture.

The current nuclear stockpile programs are the Stockpile Stewardship Program (SSP) and the Life Extension Program (LEP).  Warhead components are divided into the Nuclear Explosive Package (NEP), i.e. the actual explosive content, and the non-NEP components, i.e. casing/arming. The LEP replicates the NEP with original designs and materials but all changes are kept to a minimum; the emphasis is on maintenance of components. There is, however, a concern that in the future technical maintenance of this kind will be challenging because exact replication of components is difficult to achieve and tiny cumulative changes may affect warhead maintenance. RRW, on the other hand, would use the design parameters from the more than 1,000 nuclear tests conducted between 1945 and 1992 to identify a range of design variation within which components and warheads could be redesigned. However, whereas the worry with LEP is redundant technology, the concern with RRW is the extent of innovation that could be possible without either testing or developing new weapons.

As part of the FY 2006 Consolidated Appropriations Act, Congress mandated $25 million in funding for the two-year RRW study, which will be carried out under the joint auspices of the DOE and DOD with input from the Nuclear Weapons Council (NWC). A final report is to be presented in March 2007 with an interim update in March 2006.  The NNSA study is expected to report on the potential scope of the program in order to allow the Congress to make an informed decision on whether RRW should continue and if so, under which model. The report must include proposed infrastructure and costs, a comparative estimate of RRW and LEP warhead costs, an evaluation of the likelihood of nuclear testing, and an assessment of RRW’s position both within the SSP and on the LEP.  In commissioning the study, Congress removed language that restricted RRW to components research, demonstrating a willingness to consider a range of models for RRW barring certain constraints such as the ban on nuclear testing and the scaling back of the nuclear stockpile. However, the preliminary NNSA research design seems to be focusing on an ambitious vision of RRW that could leave the door open for designing a new nuclear weapon.

The NNSA report will be based on findings from a Submarine Launched Ballistic Missile (SLBM) warhead design competition that pairs national labs Los Alamos and Sandia, N.M., versus Lawrence Livermore and Sandia, Calif. One of the options under consideration is designing an SLBM warhead that could be compatible with Intercontinental Ballistic Missiles (ICBMs). After a design has been selected, it will be subjected to further design and cost studies before entering an advanced design development stage. The NNSA forecasts FY 2015 as a feasible end date for the production of the first RRW.

NNSA’s interim report in March 2006 will give a better indication of where research on RRW is headed, including funding projections, design competition details, and infrastructure assessments including pit manufacturing sites. It would also be wise to keep an eye on the $4 million Congress authorized “sled test” for any indications whether the Defense Department intends to utilize the results for further RNEP research.

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