Nuclear news: a “cat-litter mystery”

Followers of nuclear issues likely recall reports in February about a significant discharge of radioactive contamination at the U.S. Waste Isolation Pilot Plant (WIPP), located about 25 miles east of Carlsbad, NM. WIPP is the only government-licensed facility for long-term storage of radioactive waste. Producing plutonium for nuclear weapons, between 1943 and 2002, generated the waste being stored at WIPP.

Brookline–about 2,000 miles from the New Mexico site–is not as isolated as one might think. Contamination from WIPP apparently became airborne and, if it did so, can travel long distances. It resembles long-lived components of radioactive fallout from above-ground nuclear weapons explosions–starting in the U.S. with the Trinity site explosion of 1945 and lasting until the 1963 Nuclear Test Ban Treaty.

Nuclear waste storage: WIPP is the earlier of two U.S. nuclear-waste repositories authorized between the late 1970s and late 1980s. Construction of WIPP took from 1980 to 1988. It was designated to hold relatively low-level but long-lived radioactive waste from military programs. The other repository is Yucca Mountain, in southern Nevada. It was designated for high-level waste from nuclear power-plants. Construction began in 1992, during the Herbert Bush administration, but was halted in 2010, before completion, by the Obama administration.

WIPP construction started before the site’s geology was known in much detail. By the time construction ended, geologists had found buried faults and fractures, boreholes and aquifers above and around the salt deposits tunneled into to build WIPP. Years of disputes and further studies followed. In 1998 the U.S. Environmental Protection Agency approved WIPP as safe to use, during the Clinton administration, and in 1999 waste storage began.

Radioactive discharge event: WIPP was evacuated after sensors warned of a major radioactive discharge in underground work areas late at night last February 14. Three months later, the discharge had been traced to a drum of waste shipped to WIPP from Los Alamos National Laboratory, where plutonium processing and testing began in 1943. The Department of Energy, which runs both WIPP and Los Alamos, originally said radioactivity had been trapped in filters.

More recently, WIPP managers disclosed that 22 above-ground workers had “ingested or inhaled” radioactive contamination. At a February 23 public meeting organized by the mayor of Carlsbad, NM, a Department of Energy spokesperson estimated about 10 nCi of plutonium and other alpha-emitting elements had been released into the open atmosphere around WIPP.

The main isotope, plutonium-239, has a half-life of about 24,000 years. Reducing it to trace amounts–a billionth of current amounts–takes about 40 half-lives, or a million years. Some of the main products of nuclear fission persist much longer: technetium-99 half-life about 220,000 years, iodine-129 half-life about 17,000,000 years.

The 1980s designers and 1990s certifiers of WIPP looked only 10,000 years ahead–just an instant in time, compared to long-lived radioactivity and to geology. In at least the million years they should have considered, geologic history has seen about eight full glacial cycles. The most recent of those left the Great Lakes and the Grand Canyon.

Hazards from the atmospheric release of radioactivity estimated by the Department of Energy last February 23 would be small for people miles from the plant, as department personnel say, but they are hardly zero, since alpha emitters are powerful inducers of tumors. Far more radiation has evidently spread through underground tunnels. The Department of Energy has not allowed workers to resume ordinary activities underground. As of May, 2014, WIPP remained effectively shut down.

Power-plant waste: In addition to high-level radioactive waste–spent fuel rods–nuclear power-plants also generate low-level waste, containing some long-lived radioactivity similar to waste being stored at WIPP. That consists of used filter elements, residues from cleanups, contaminated tools and clothing, and other byproducts of routine operations. Like the other 103 licensed nuclear-power reactors in the U.S., the reactor at the Pilgrim plant in Plymouth is holding both spent fuel rods and low-level waste on-site.

Eventually, low-level power-plant waste is currently destined for a privately run repository that is under construction in west Texas. The principal investor in Waste Control Specialists, located about 35 miles west of Andrews, TX, was the late Harold C. Simmons. Mr. Simmons was also a well known contributor to “Swift Boat Veterans for Truth,” the group that broadcast attacks on former Sen. John Kerry, now the U.S. secretary of state, during the 2004 Presidential campaign.

High-level nuclear waste is another story. In addition to alpha-emitting elements such as plutonium, irradiated fuel contains nuclear-fission products that emit intense beta and gamma radiation–notably strontium-90 and cesium-131, both with half-lives of about 30 years. Several minutes of exposure to an irradiated, unshielded fuel rod can be fatal.

Sources of high-level waste are former factories for nuclear weapons and nuclear power-plants. U.S. weapons factories left the equivalent of about 2,500 metric tons of heavy metal in plutonium-processing wastes, separated from the plutonium that was used to make weapons. As of 2014, the U.S. nuclear-power plants have left about 73,000 metric tons of heavy metal in unprocessed spent fuel–97 percent of the U.S. total high-level wastes.

Rated capacity of the unfinished, now idle Yucca Mountain repository is only 70,000 metric tons of heavy metal. At current rates, another facility of that size is needed about every 40 years. Most high-level waste is being stored where it was made. The large storage sites in New England are closed power-plants in Wiscasset, ME, Haddam Neck, CT, and Rowe, MA, and active power-plants in Waterford, CT, Portsmouth, NH, Plymouth, MA, and Vernon, VT.

“Government misadventure”: Writing in the New York Times, before the February 14 radioactive discharge at WIPP, veteran reporter Matthew L. Wald called storage of low-level radioactive waste “a government misadventure.” Among the most difficult issues are unexpected events. No one expected waste that had already been in storage for years to explode, but that is what the drum from Los Alamos apparently did at WIPP. A photo published online shows a gaping hole in the drum’s lid.

Laura Zuckerman, writing for Reuters, recently reported that contents of the failed drum heated, because of some unexpected chemical process. Jeri Clausing, writing for Associated Press, reported that one of the main suspects has been commercial cat litter packed around waste containers. Cat litter had long been used as a packing material to absorb liquid leaks. However, for the failed drum, instead of clay composition, available since the 1940s, Los Alamos reportedly used one of the newer cellulosic compositions–also known as “organic.”

“Cat-litter mystery”: News articles report speculation that somehow nitrates in waste reacted with cellulose in “organic” cat litter to create a highly flammable or explosive material. Since the 1820s, it has been known that cellulose can react to form flammable or explosive nitrocellulose–also called “guncotton.” However, that requires a strong acid, usually nitric acid.

Plutonium processing typically uses high-strength nitric acid to dissolve irradiated reactor fuel, as the start point for extracting plutonium. Before wastes from processing are stored, they are ordinarily mixed with alkali compounds to neutralize acids, so that wastes can be held in plain metal tanks. In a laboratory setting, however, strong acid wastes might have been stored in glass or other nonmetal containers. Until contents of the failed drum at WIPP have been examined, a “cat-litter mystery” endures.

– Craig Bolon, Brookline, MA, May 23, 2014

Update, slow progress: As of May 30, 2014, the U.S. Department of Energy has stopped sending nuclear waste from Los Alamos to WIPP. In a notice to the New Mexico Environment Department, it estimated two to four years to clean up and reopen WIPP. Other, major clean-up efforts are likely to be affected: notably those at the Savannah River and Hanford sites in South Carolina and Washington state, which produced nearly all the plutonium used for the U.S. nuclear arsenal.

Jeri Clausing, Associated Press, Feds say it could take 2 years to seal nuclear waste site, Billings (MT) Gazette, May 31, 2014

Jeri Clausing, Associated Press, Has cat litter turned barrels of New Mexico nuclear waste into ticking time bombs? Minneapolis Star Tribune, May 23, 2014

Jeri Clausing, Associated Press, WIPP leak linked to container from Los Alamos National Laboratory, Albuquerque (NM) Journal, May 17, 2014

Steve Sandoval, Communications Office, Los Alamos National Laboratory ships last of high-activity drums to WIPP, Los Alamos National Laboratory, November 25, 2008

Laura Zuckerman, New Mexico official urges removal of nuclear waste drums that could leak radiation, Reuters, May 16, 2014

Laura Zuckerman, Possible radiation leak at New Mexico military nuclear waste site, Reuters, February 16, 2014

Matthew L. Wald, Texas company owns national radioactive waste monopoly, New York Times, January 21, 2014

Matthew L. Wald, South Carolina threatens over cleanup of nuclear waste, New York Times, November 29, 2013

U.S. Circuit Court of Appeals for the District of Columbia Circuit, Nuclear Energy Institute v. Environmental Protection Agency, No. 01-1258, July 9, 2004 [373 F.3d 1251] sourced from U.S. EPA

Robert Vandenbosch and Susanne E. Vandenbosch, The revised radiation protection standards for the Yucca Mountain nuclear waste repository, Forum on Physics and Society, American Physical Society, 2009

Richard A. Kerr, For radioactive waste from weapons, a home at last, Science 283(5408):1626-1628, March 12, 1999

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