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Some Nuclear Experts Question Ramp-up in U.S. Tritium Production
WASHINGTON -- 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, 10 tritium-irradiation cycles -- each taking about 18 months -- have been completed.
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 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.
U.S. nuclear weapons policy calls on the Energy Department to maintain fresh tritium in the deployed arsenal of atomic warheads carried by ICBMs, submarine-launched missiles and bomber aircraft.
Continuing a policy from previous administrations, the Obama White House is also keeping roughly 2,290 warheads in an active hedge reserve force that receives regular maintenance and is kept stocked with tritium, according to Nuclear Matters. This stockpile hedge force constitutes more than one fully assembled backup warhead for each strategic warhead deployed at bomber aircraft bases, on ICBMs or on submarine-launched ballistic missiles.
The State Department last week announced that the nation now has 1,790 operationally deployed warheads, as the United States gradually reduces to a limit of 1,550 fielded weapons under the U.S.-Russian New START agreement (see GSN, Oct. 26).
One key distinction between a warhead in the active force -- either deployed or hedge -- and one that has been deactivated is that the tritium reservoir in the active warhead is routinely replaced every few years to ensure that the weapon's radioactive gas does not expire.
The hedge warheads are maintained in active reserve status in case "an unforeseen catastrophic failure of a class of delivery vehicles, warhead-type or family" is discovered or there is "an unexpected reversal of the geopolitical situation that would require an increase in the number of weapons available for use," according to the Pentagon handbook.
Kristensen sees this as overkill and a waste of resources.
"I think it's totally unnecessary to retain active weapons in the hedge," he said in an interview this week. "Short of a Martian attack, there's nothing that would require us to suddenly upload 2,000 warheads onto the force. It's not going to happen."
Finding a technical defect that puts a portion of U.S. warheads out of commission is perhaps more plausible than a resurgent-threat scenario in justifying the retention of a hedge force, Kristensen said. However, if such a flaw was discovered, it could likely be handled quietly over time without a need for massive warhead swap-outs from the active reserve stockpile, he argued.
"Would it really require us to have active weapons that we'd have to upload immediately?" he said, calling for a "reality check" on how big of a backup nuclear force is truly needed. "The rest of the force would still be good. We'd have enough [other] warheads left to bomb Russia back to the Stone Age."
In fact, the Pentagon anticipates reducing the size of the active stockpile hedge force in coming years as warhead maintainers develop more replacement components that could help aging weapons remain functional (see GSN, Aug. 18).
It is unclear, however, if long-term plans for reductions in the active hedge force have translated into a lower requirement for the amount of tritium that must be produced in the years to come.
"The United States is in an era of fiscal constraint with an unprecedented debt and a substantial annual deficit," Ferguson said. "Political leaders need to take a very serious examination of additional costs for maintaining a rather large reserve stockpile of warheads."
More than a decade ago, he joined Princeton physicist Frank von Hippel in a 1999 letter published by Physics Today estimating that given the amount of tritium available, its rate of decay and the standard use of recycling, a U.S. nuclear arsenal numbering 4,500 warheads could be sustained without new tritium production through 2025.
The pair noted that the Energy Department at the time had established a requirement to maintain a five-year reserve supply of tritium.
Assuming that the backup tritium-supply policy has not changed and the nation continues to keep its roughly 5,000-warhead arsenal maintained with fresh tritium, "then the year would be 2022" in which new gas would have to be produced, von Hippel said this week in an e-mail response to questions. "But probably DOE still has more than a five-year reserve [available] and is getting nervous that it will be approaching that level in a few years."
Additional tritium has been produced since the two scientists calculated their 1999 estimates, which should result in an even deeper cushion of reserve gas, Ferguson noted.
Von Hippel said a national production schedule for tritium should account more realistically for how hedge-force warheads are actually managed.
In the unlikely case that an emergent threat dictated a more urgent need for new tritium, "it might take a few years to produce enough for 2,000 additional [deployed] warheads," but the United States would almost certainly have at least that much warning time that more tritium is needed, he said. "[Or,] if a problem developed with some deployed warheads that required them to be replaced by reserve warheads, the tritium could be swapped."
Linton Brooks, who served as the first NNSA administrator during the Bush administration, played down debate over the issue. He noted that hedge force weapons do not have to be kept at an immediately usable state of readiness because upload schedules for operationally deploying those warheads would be largely driven by weapon delivery systems.
"Uploading the entire force would take months for submarines (driven by patrol schedules, since we would not want to reduce the number of survivable missiles) and years for the ICBM force (driven by handling equipment)," he said in a Thursday e-mail message.
Further nuclear-weapon reductions through arms control agreements or unilateral deactivations could allow Washington to produce tritium even later down the road, von Hippel told Global Security Newswire.
Were Washington to cut the active stockpile in half from the current 5,000 or so warheads to a level of 2,500, "we would buy ourselves 12 years of no tritium requirements and still have a reserve for 800 warheads," he said.
Given "a significant amount of tritium on hand" today -- freed up by post-Cold War warhead retirements -- Brooks said he "would advocate matching production capability with probable upload schedules, since producing excess tritium has little value."
Others raised additional tolls that tritium production might take.
"I don't think people realize that this material is being produced in a commercial reactor and it does have environmental and health implications near the production sites," said Tom Clements, the southeastern nuclear campaign coordinator for Friends of the Earth.
He said that heightened levels of tritium are present in groundwater near the tritium-handling facilities, and that the long-term consequences are not well understood even if the chemical levels fall within of government-approved limits.
"If there is no good reason to maintain the warheads, we need not pay any financial or environmental costs," von Hippel said.
Clements also took issue with the Energy Department's use of Watts Bar to produce tritium for ultimate use in U.S. warheads.
"I definitely don't think commercial reactors should be used to produce nuclear weapons material because it sends the wrong nonproliferation message to the entire world," he said. "It clearly crosses the imaginary line between the military and commercial nuclear fuel cycles. And the United States should be doing everything possible to keep them distinctly separated."
Clements said there has been some discussion of making some of the Watts Bar tritium available to industry for commercial purposes, but he said specific uses and timing remained unclear.
However, "the biggest concern is that the United States is keeping reserve weapons under the New START treaty fully capable of being deployed in a short period of time," he said. "And I think that undermines the goal of eventual, complete disarmament of nuclear weapons."
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