Friday, May 3, 2013

Texas physicist proposes solution to nuclear waste problem

Peter McIntyre
We found this on PR Newswire today and thought it might be of local interest, considering the local interest among some with regard to all things nuclear and the mention of Idaho National Laboratory.

COLLEGE STATION, Texas -- In the mind of Texas A&M University physicist Peter McIntyre, two of America's most pressing energy challenges — what to do with radiotoxic spent nuclear fuel and dwindling energy resources — can be solved in one scientific swipe. He is developing the technology that is capable of destroying the dangerous waste and, at the same time, potentially providing safe nuclear power for thousands of years into the future.

In his high-energy physics laboratory east of the Texas A&M campus, McIntyre and his research team are developing a new form of green nuclear power that would extract 10 times more energy out of spent nuclear fuel rods than currently obtained in the first use, as well as destroy the transuranics — the chemical elements beyond uranium in the periodic table — lurking within the hazardous toxic soup of used nuclear fuel

Buoyed by seed funding from Texas A&M University ($750,000) and the Cynthia and George Mitchell Foundation ($500,000), McIntyre is preparing a proposal to the U.S. Department of Energy seeking the large-scale funding that would enable him to take the next steps.

Although viewed as a major national issue, McIntyre says the nuclear waste problem is a multifaceted one for which no viable solution yet has emerged, despite decades of discussion. Most recently in 2010, federal authorities scrapped a plan to create a nuclear waste dump at Yucca Mountain in Nev., to store the nationwide spent nuclear fuel capacity that now stands at 65,000 tons.

"In my opinion, the only way to properly deal with transuranics is to destroy them," McIntyre said. "They are an unthinkable hazard if they ever get into the biosphere. There has long been discussion that we could find a site like Yucca Mountain that's so isolated from groundwater and so stable geologically that we could say with confidence it will be the same 100,000 years from now as it is today, and that burying fuel there, closing the door and forgetting it is something we can responsibly do. I don't buy those arguments."

Each of the nation's 104 reactors is fueled with about 90 tons of enriched uranium fuel, packaged in sealed metal tubes called fuel pins. As the uranium fissions, the byproducts are trapped inside these pins, where they accumulate and begin to take on neutrons that would otherwise be driving the continuing fission process. The ongoing build-up, which includes the heavier transuranic elements, renders the reactor non-operational after about five years once the fission process stops. At this point, the pins are replaced with a new set, and the spent fuel typically is stored in a pool of water at the reactor site.

McIntyre, a professor since 1980 in the Department of Physics and Astronomy and the inaugural holder of the Mitchell-Heep Chair in Experimental High-Energy Physics within the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, describes his team's technology as a "win-win."

"It destroys the bad stuff — the transuranics — and recovers the good stuff — the fuel," he said.
To destroy the transuranics, McIntyre's team has developed a conceptual design for accelerator-driven subcritical fission in a molten salt core (ADSMS). With this technology, the transuranics are extracted into molten salt using a process called pyroprocessing, in which the spent fuel pins are chopped up and loaded into a basket, which is placed in a pot of molten salt. The oxide fuel inside the pins dissolves in the molten salt so that all of the remaining fuel — along with all of the transuranics — is extracted into the molten salt. The transuranics could then be destroyed through subcritical nuclear fission, which is driven by a beam of energetic protons within the custom-built, high-efficiency accelerator he envisions. 

McIntyre's design builds on work at Argonne National Laboratory and Idaho National Laboratory as well as the PRIDE facility in South Korea which demonstrated the process for extracting the fuel and separating the transuranic elements and fission products in molten salt. Scientists from those teams are collaborating with McIntyre in the new development.

"In the same process by which we extract the transuranics from the spent fuel, we also extract the uranium so it can be re-used as an ongoing energy resource to provide nuclear energy for the next several thousand years," McIntyre said.

The idea isn't new. But earlier proposals for accelerator-driven subcritical fission faced the problem that there was no known way to deliver the necessary proton beam power to a core. The ADSMS design uses a novel invention of McIntyre's called the strong-focusing cyclotron. In the strong-focusing cyclotron, bunches of protons are accelerated through superconducting radio-frequency (RF) cavities and focused using superconducting beam transport channels. These proton bunches are continually re-focused to contain high-beam current within the accelerator aperture — an approach that McIntyre says makes it possible to deliver 10 times more fission-driving beam power than previously achievable, and to do it with high-energy efficiency.

"We are preparing a proposal to the DOE to build and put into operation a first model of this strong-focusing cyclotron," McIntyre said. "It would be quite an advance in the field of accelerator physics unto itself. But most particularly, for the first time, it will make it feasible to drive a subcritical fission core capable of destroying transuranics at the same rate they are made in a power reactor."

McIntyre knows the hurdles ahead for his project, including convincing federal officials to make a major scientific investment during an age of cutbacks, and proposing a new and better way for nuclear power at a time when Fukushima is fresh in the public mind. (McIntyre notes that the Fukushima explosions in 2011 involved spent fuel storage pools, a problem his technology would eliminate.)

But the road the 65-year-old scientist treks has a familiarity to it. He zigzagged the state and nation in the 1980s — also a time of fiscal restraint — to make the scientific and political cases for another major project, the Superconducting Super Collider (SSC), which would have accelerated particles to nearly the speed of light and maintained American supremacy in high-energy physics. Congress killed the SSC 20 years ago, and the prospect of big discoveries at the frontier of high-energy physics gravitated to CERN in Switzerland, which celebrated the discovery of the elusive Higgs boson on July 4 last year.

Physicists, including Stephen Hawking, have lamented the loss to American science represented by the failure of the SSC, but McIntyre sees a silver lining to that effort: It gave him invaluable experience at figuring out how to connect science with the political leaders who could bring it to fruition, skills the grayer and wiser McIntyre is using now. Back in the 1980s, he ended up making a presentation about the SSC in the West Wing of the White House to then-Vice President George H.W. Bush, who subsequently asked for a two-pager to carry to President Ronald Reagan .

"That moment was the birth of the SSC," McIntyre said. "That's how things can happen, and that's how they do happen in this world. It takes persistence and ingenuity in trying to find a way."

To learn more about McIntyre and his research, go to http://people.physics.tamu.edu/mcintyre/.