Performance Drives the B61 Bomb Update

, Washington representative and senior analyst | October 29, 2013, 14:53 pm EST
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If you look at what officials say about the life extension program for the B61 nuclear bomb, they mention again and again how old the warhead is. Here is Don Cook, NNSA’s deputy administrator of defense programs, before the House energy and water appropriations subcommittee on February 14, 2013:

We have engaged in a thorough analysis of what’s required to extend the life of the oldest weapon we have in the deterrent, and that is the B61. There are elements of that weapon that are 40 years old; a lot that are 30 years old. There are fewer that are 20 years old.

When not talking about age, officials highlight safety and security. Don Cook again, at the same hearing:

Our principal focus is on improvement of safety and improvement of security. We — we retain the weapons at a reliable state. We must and will continue to do so. But we know how to improve safety and security, and we’ve had about three decades where those elements have not been the focus . . . Now we’re doing them for the 61 and — and 76, the 78 and the 88.

It is worth highlighting—as we already have—that the independent science advisory group JASON notes the B61 already has “substantial safety and security capabilities.” These include using an insensitive high explosive that is less likely to explode in an accident and some of the most sophisticated permissive action links to prevent unauthorized use.

But given those official quotes, one might expect that the B61 life extension program would focus on aging and/or safety and security issues.

Performance Rules the Day

The FY 2014 Stockpile Stewardship and Management Plan produced by the NNSA provides an actual data set to examine, rather than just words. Based on that data, the “life extension program” is largely about improving performance.

How can we tell? The NNSA’s plan describes in some detail the status of all of the components and technologies that are being developed for the new version of the B61. For each of those, it identifies the driving factor for why the new element will be incorporated.

Selected Non-nuclear Component Technology Development

Subsystem or Category



TBSTP Technology\ Driver

Applicable Systems: TRL

Arming fuzing and firing system Fuzing Radar Performance B61-12 LEP: TRL 4
Arming fuzing and firing system Fuzing Radar and JTA antenna Performance B61-12 LEP: TRL 4
Arming fuzing and firing system Fuzing Weapon control unit Performance B61-12 LEP: TRL 4
Neutron generator Neutron generator Electronic neutron generator Performance B61-12 LEP: TRL 6
Surety Stronglinks Electrical Contact Stronglink
Trajectory Stronglink
Performance, Enhanced Surety ECSL: B61-12 LEP: TRL 5
TSL: B61-12 LEP: TRL 4
Surety Processor Validating information processor Aging, Performance, Enhanced Surety B61-12 LEP: TRL 5
Surveillance Flight test JTA Optical transduce assembly Performance, Aging B61-12 LEP: TRL 4

ESCL = Electrical Contact Stronglink
JTA = Joint Test Assembly
LEP = life extension program
TBSTP = Technical Basis for Stockpile Transformation Planning
TRL = technology readiness level
TSL = Trajectory Stronglink

Source: Fiscal Year 2014 Stockpile Stewardship and Management Plan, U.S. Department of Energy, June 2013.

As laid out above, of the eight non-nuclear component technologies under development, performance is a driver in all eight, enhanced safety/security is a driver in three, and aging is a driver in two.

For example, several new technologies are being planned for the warhead’s arming, firing and fusing mechanism, including the radar and the “weapon control unit.” The radar is one of the components that needs to be replaced. Rather than simply putting in a newly-built version of the current model or using a newer but existing type, the NNSA is developing a brand new version. This choice drives up the cost of the program and takes more time.

Selected Nuclear Explosive Package Component Technology Development



TBSTP Technology Driver

 Applicable Systems: TRL

HE Remanufacture of TATB B61-12 LEP: TRL 5
HE Booster Robust IHE Booster Performance, Surety B61-12 LEP: TRL 5
Initiation system Direct Optical Initiation Performance, Surety B61-12 LEP: TRL 5
Pit Reuse Aging, Performance B61-12 LEP: TRL 5
CSA Reuse Aging, Performance B61-12 LEP: TRL 5
Case Recertification and reuse Performance B61-12 LEP: TRL 4
Flight test JTA Telemetry package Performance B61-12 LEP: TRL 4
Flight test JTA Robust monitors Performance B61-12 LEP: TRL 4

CSA = canned subassembly
HE = high explosive
IHE = insensitive high explosive
LEP = life extension program
JTA = Joint Test Assembly
TATB – triaminotrinitrobenzene
TBSTP = Technical Basis for Stockpile Transformation Planning
TRL = technology readiness level

Source: Fiscal Year 2014 Stockpile Stewardship and Management Plan, U.S. Department of Energy, June 2013.

For the eight technologies in the B61’s nuclear explosive package, the focus on performance is similarly high: It is a key driver in seven. Of those seven, aging is also a driver in two, and safety/security is a driver in another two. (One element, remanufacturing the high explosive, does not list a driver, although that presumably is an aging issue.)

Selling Security?

There is one change that is not a new technology but has been described by officials as improving security. That is the proposed B61-12 will have less highly-enriched uranium (HEU) than is in some existing B61 variants. Officials note that the new version will be based on the B61-4, which reportedly has a maximum yield of 45 kilotons. That is considerably less than the reported maximum yield of the B61-3, at 170 kilotons, or the B61-7, at 340 kilotons.

On average, U.S. nuclear weapons have some 15 kilograms (kg) of HEU in the secondary, and some, including the B61, also have about 10 kg of HEU in the primary. It takes about 50 kg of HEU to make a gun-type device, but only about 20 kg to make a relatively simple implosion device. Thus, if one bomb was stolen it would not contain enough HEU to allow someone to make a gun-type device. However, depending on the design, it might contain enough to allow an implosion device.

In fact, from the way officials have described the improvement in security in the B61-12, one might speculate that the HEU from one B61-4, if melted down and re-configured into a new weapon, would not be enough to create an implosion-type nuclear device, while the HEU from a B61-7 might. If true, the new model would provide some security benefit.

However, the greatest security risk is from the warheads stored in Europe, the B61-3s and -4s, which are the most vulnerable to loss or theft. According to Bob Peurifoy, the retired vice president at Sandia who was directly involved in developing the B61 mods, the difference in maximum yield between the B61-3 and the B61-4 is not a function of a significantly larger amount of HEU. Assuming that is the case, the argument that the B61-12 will significantly improve security because it uses less HEU is not nearly as strong.

Actions, Words

In sum, while much of the talk about the B61 life extension program has been focused on concerns about the aging of a warhead that was first built in the late 1970s and the need to improve the safety and security of the stockpile, the reality appears to be that much of the work for the “life extension program” is to improve performance.

Given the NNSA’s failure to win Congressional support for the Robust Nuclear Earth Penetrator and the Reliable Replacement Warhead, which focused on enhancing performance in the former and reliability (at least in how it was discussed) in the latter, agency officials know that they cannot get funding for the B61-12 using those approaches. Instead, it seems that they are highlighting aging and security concerns as a more likely avenue to ensure funding for a major work program.

In a time of increasing budget pressures, creating story lines that seek to obtain funding for your programs is a natural phenomenon. But when nuclear weapons play a smaller and smaller role in U.S. security, Congress should look carefully at what is actually planned, rather than the words used to describe it.

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