Los Alamos Monitor

January 7, 2007

Guest Column

Pit production: no value added

Late this year, Los Alamos National Laboratory (LANL) may begin production of plutonium warhead cores (“pits”).  Pit production is the pivotal, rate-determining step in making new warheads, in this case half-megaton W88s for Trident submarines.  Production of Reliable Replacement Warhead (RRW) pits, if approved, is supposed to follow in FY2012 or earlier. 

The consequences of this new mission, should it continue – for the lab, the workers, and the town – are weighty.  Hindsight may reveal that some of these consequences have already begun.  Consequences for U.S. non-proliferation efforts are weightier still. 

Leaving aside for now the very important costs, consequences, and hidden motives, is pit production necessary in any sense? 

Additional Trident warheads provide no marginal benefit.  The U.S. has about 3,400 Trident warheads, of which roughly 380 are W88s, the balance being 100-kiloton (kt) W76s.  There are hundreds more W76s than are deployed.  Over 1,000 W76s are likely to be retired by 2012, when the National Nuclear Security Administration (NNSA) has said the stockpile will be much smaller.  Even the super-hawkish Defense Science Board prefers a stockpile in which no single warhead comprises more than 20% of the total, requiring at least 1,200 W76 dismantlements. 

A life-extension project (LEP) is beginning which would substantially revamp the remaining W76s, adding 20-30 years to its service life and adding “features” now found on the W88 such as ground-burst fuzing (for “hard-target kill”).

The W76, originally made for a smaller and less accurate missile, is now carried on the D-5 missile just like the W88.  It may have (I do not know) accuracy comparable to the W88.  What targets to be assigned to new W88s could not be destroyed by W76s after the planned upgrades?   If any, is this stabilizing or destabilizing? 

The difference between 475 kt and 100 kt is not that much, since the radii of destruction (both above and below ground) scale roughly as the cube root of the yield.  

Thanks to LANL scientists and others, we know that pits do not age in any way requiring pit production before mid-century.  Today’s (and tomorrow’s) facilities will be worn out by then.  All other components can be assessed accurately as they age and replaced as desired without making new pits. 

In the extremely unlikely event of total Trident pit failure there are extra pits to replace them.  The U.S. has approximately 13,000 (possible more) surplus pits of various kinds, in addition to the 10,000 or so pits in stockpiled weapons.  Designs involving some of these have been developed and even tested.  Currently-proposed stockpile reductions would transfer roughly 4,000 pits from stockpile to surplus.  A replacement Trident warhead was designed in the late 1990s that used recycled pits, which were numerically adequate even prior to currently-planned stockpile reductions.  This “mature design” did not require (further) nuclear testing.

All parties agree there are no safety, security, or reliability problems with any U.S. warhead.  None are expected and programs are in place to ensure that none occur.  Performance margins of all U.S. warheads have been repeatedly judged adequate by all parties and could be improved if desired during maintenance.  There have been at least 10 internal reviews (during the annual certification process) and at least one external JASON review on this point. 

Apparently neither DoD nor NNSA are that attached to the W88.  In the mid-1990s then-Admiral Nanos wrote that both Trident warheads were “exiting,” to be replaced by unspecified new warhead(s).  NNSA has said it wants to replace all U.S. warheads with the proposed RRW warhead “family.”  No strategic justification has been offered for making more W88s. 

In fact the number of W88s is arbitrary, having been determined by the sudden closure of the Rocky Flats Plant near Denver in 1989.  Since then, destructive surveillance has diminished the W88 inventory slightly and will continue to do so.  This, however, creates no need for “replacement” warheads.  “Replacement” is just a semantic dodge.  These are to be new warheads, expanding available inventory. 

The minimum acceptable pit production rate appears to be the maximum NNSA can get away with.  Technically and militarily, none are needed.  Why do it, when the costs are so great? 

Greg Mello is the director of the Los Alamos Study Group.