Why LANL cannot host a plutonium pit factory

By Greg Mello, Guest Columnist
Sunday, January 13, 2019

At the end of the Cold War it made sense for the Department of Energy (DOE) to consolidate and temporarily preserve pit production technology at LANL. Given the National Nuclear Security Administration’s(NNSA’s) mandate, it still does.

However, hopes for a reliable, small, pit production capacity at LANL – let alone an enduring one that could quantitatively contribute to maintaining the nuclear stockpile over decades – didn’t pan out.

In 1989, when the Berlin Wall came down and the Rocky Flats Plant madeits last pit, PF-4 was only 11 years old. The extent of LANL’s seismic hazard was then unknown, officially at least.

Likewise, the poor geotechnical properties of the unconsolidated volcanic sediments at LANL’s TA-55 were unknown then.

They were certainly plain to see in the surrounding terrain and in records of TA-55 borings.

When LANL was chosen for the pilot pit mission in late 1997, no further construction at TA-55 or elsewhere at LANL was thought necessary. Or at least that was the story. So the presence of an 80 or so foot thick layer of poorly consolidated volcanic ash – dust, more or less – beneath TA-55 seemed of no particular relevance. It was apparently not brought to management attention. Institutionally it was forgotten until 2010, when engineers discovered that this problematic stratum would have to be entirely removed to build a nuclear facility on the south side of TA-55.

Likewise LANL’s dissected, steep topography, which dramatically increases costs and places firm limits on construction at TA-55 and elsewhere at LANL, was not a factor in 1997, when PF-4 was in mid-life and no new construction was envisioned.

The situation is much different now, 20 years later. Originally designed for a 50-year operational life, PF-4 is now 40 years old. By the time pit production is supposed to start in earnest in the late 2020s it will be 50. PF-4 was not built to modern nuclear facility standards. It also was and is an R&D facility, not a factory. Its structural integrity in the event of a design basis earthquake, and the adequacy of its safety systems in routine operation and more so in a design basis accident, have been under constant review, critique, negotiation, upgrade, and repair for the past decade and more. It does not have safety-class ventilation or fire suppression systems. Safety is a perennial “work in progress.”

NNSA has said it expects PF-4 to last until 2039 [1] (p. WA-211), but with what confidence, or operational reliability?

With what safety risks? No one really knows.

In June 2017 the NNSA determined [2] (p. 76) that continuing to rely on PF-4 for enduring pit production capability presented “unacceptably high mission risk,” for two reasons: a) efforts to install equipment in PF-4 beyond what is already planned under the Plutonium Sustainment program present unacceptably high risks to achieving 30 ppy production by 2026; and b) PF-4 is much smaller than is required for stockpile pit production, even if missions such as plutonium dioxide production and plutonium-238 manufacturing were somehow relocated.

Could a suite of single-story underground production “modules” provide enough increased program capacity, either to expand LANL pit production or to replace PF-4?

In a word, no. No matter how many safety and operational corners are cut to save space – current plans involve cramped underground facilities and access, lack safety-class systems, and do not meet nuclear design regulations – there just isn’t room.

NNSA and DoD have little choice but to use LANL for “technology transfer” of the pit production mission to the Savannah River Site (SRS). For industrial pit production LANL can only be, at best, a training site.

In objective terms, NNSA’s only decent option for a reliable pit factory for the coming decades lies with the brand-new, largely-built, unused, uncontaminated and therefore easily reconfigured, heavily-constructed, “plus-sized” Mixed Oxide Fuel Fabrication Facility (MFFF) at SRS in South Carolina, built to process tens of tons of plutonium for another (now defunct) program. Nothing at LANL or at any other NNSA or DOE site comes close to MFFF’s relatively high feasibility, low cost and risk, and relatively “rapid” schedule for starting up pit production.

That said, nothing about making a pit factory is easy, cheap, low-risk, or quick – or necessary any time soon to maintain any U.S. nuclear weapon system for decades to come. The US has more than 10,000 long-lived pits of modern, usable types that will last several more decades.

Barriers to industrial pit production at LANL are many, intractable, synergistic, and largely independent of anything Congress or the Triad management team might do. It will be more than just “difficult,” or “risky,” for LANL to establish reliable, enduring industrial plutonium missions, including industrial pit production at any scale.

For many reasons – far more than fit in this column – it will be impossible.

The sooner this is realized, the better – for LANL, the nation, and this state.