The U.S. nuclear complex is expanding production of an exotic gas widely seen as essential for keeping nuclear weapons functioning, but some progressive issue experts cast doubt on just how much new fabrication is required (see GSN, Aug. 25).
The Energy Department's semiautonomous National Nuclear Security Administration plans over the next few years to more than triple capacity to produce tritium at the commercial Watts Bar reactor in eastern Tennessee, according to the agency's fiscal 2012 Stockpile Stewardship and Management Plan.
This budget year alone, the agency is seeking a $27.3 million boost for its "tritium readiness" effort, in which production will increase from 240 to 544 rods per cycle at a cost of $77.5 million, the NNSA fiscal 2012 funding request to Congress states. Since production began at the Tennessee Valley Authority reactor in 2004, it has completed 10 tritium-irradiation cycles -- each taking about 18 months.
The readiness program also includes the process of extracting tritium from the irradiated rods at the Energy Department's Savannah River Site, located on South Carolina's western border with Georgia, and of maintaining military reserves of the gas.
By 2020, the agency intends to boost production to 1,700 rods each cycle, according to Terry Johnson, a TVA spokesman. The Obama administration seeks to spend $270.5 million on tritium readiness between fiscal years 2013 and 2016, producing no fewer than 240 rods per cycle as a minimum "sustaining rate" during that period.
This will "ensure a capability is available in the event that future resources are allocated to ramp up production to support the requirements" of a future U.S. nuclear stockpile, the funding plan states. The blueprint also calls for extracting tritium at a clip of no less than one batch of rods per year.
Thanks to post-Cold War reductions in the size of the nuclear stockpile, the Energy Department now needs less new tritium than initially projected in May 1999, according a recent federal notice.
However, tritium production has gone a bit slower than anticipated because more of the gas than expected has leached from rods at Watts Bar into reactor coolant water. That has left slightly less tritium available to extract from each rod, Johnson said.
The nuclear agency is thus exploring options for further increasing its production capacity, the notice states.
However, not everyone sees new production as a must. Some experts are questioning why a standard practice of recycling tritium from deactivated nuclear warheads is not offering sufficient reserve stocks of the gas, particularly given anticipated arms-control reductions and further weapon retirements from the strategic hedge force.
If the United States can deactivate warheads at an average rate of at least 5 percent every year, "there would be no need to produce additional tritium," said Charles Ferguson, president of the Federation of American Scientists. That would offset the roughly 5 percent rate of annual decay in tritium in the remaining warheads, he said.
On occasions when warheads are shifted out of the operationally deployed stockpile or ready-reserve force, tritium gas is typically removed, purified, and reused in weapons that are still active, the career physicist and a number of other experts said.
The nation removes tritium from inactive stockpile warheads "as soon as logistically practical, and the tritium is returned to the national repository" at Savannah River, according to the Defense Department's 2011 "Nuclear Matters Handbook." The government has not elaborated on the rate at which this is done or exactly how much reserve supply is available today.
A mix of tritium -- a radioactive isotope of hydrogen -- and deuterium is maintained in a small reservoir in each U.S. nuclear weapon to boost the warhead's explosive power. Just a few grams of the gas, injected into the hollow pit of a warhead's primary stage, initiate a chain reaction and trigger a much more powerful secondary stage.
To make a nuclear weapon detonate, "this is where the rubber hits the road," said Hans Kristensen, who directs the FAS Nuclear Information Project. "If you can get the primary to go off with enough yield, then the secondary will go off."
Conversely, if a warhead's tritium-dispenser bottle has been removed or if the gas has significantly deteriorated, the secondary stage could fail to ignite and the explosive power of the weapon would be considerably diminished, experts explain.