On Valentine's Day 2014, a drum of packaged waste from the Los Alamos National Laboratory (LANL) ruptured 2,150 feet (655 metres) underground in New Mexico's nuclear waste repository known as the Waste Isolation Pilot Plant (WIPP) which is carved from ancient salt beds. The incident was described as a heat-generating chemical reaction – the US Department of Energy (DOE) called it a deflagration rather than an explosion.
Explosion or not, the chemical reaction compromised the integrity of a barrel and spread contaminants through more than 3,000 feet of tunnels, up the exhaust shaft, into the environment, and to air monitoring equipment approximately 3,000 feet north-west of the exhaust shaft. The accident resulted in 21 workers receiving low-level internal radiation exposure.
It later transpired that LANL had improperly packaged hundreds of waste drums with a combustible mix of nitrate salts – a byproduct of nuclear weapons production – and organic cat litter, causing a hot reaction in one drum that cracked the lid. The rupture released americium and plutonium into the deep salt mine and, in small amounts, into the environment.1 The repository is still closed two years later, and a March 2016 date for re-opening has been pushed back to later this year.
"These accidents during the first 15 years of operation really illustrate the challenge of predicting the behavior of the repository over 10,000 years," said Rod Ewing, the Frank Stanton Professor in Nuclear Security at Stanford and a senior fellow at the Center for International Security and Cooperation.
The Stanford experts also suggest more attention should be paid to how the buried materials may interact with each other, particularly with salty brine, over centuries. A single storage drum may contain a variety of materials, such as lab coats, gloves and laboratory instruments; thus, the chemistry is complex. Ewing said that the complacency that led to the accidents at WIPP can also occur in the safety analysis. Therefore, he advises, it is important to carefully review the safety analysis as new proposals for more plutonium disposal are considered.2
Now, 500 metres beneath the forests of northern Germany, in an old salt mine, another nightmare is playing out, according to Fred Pearce in the New Scientist. Enough plutonium bearing radioactive waste is stored here to fill 20 Olympic swimming pools. When engineers backfilled the chambers containing 126,000 drums in the 1970s, they thought they had put it out of harm's way forever. But now, the walls of the Asse mine are collapsing and cracks forming, thanks to pressure from surrounding rocks. So the race is on to dig it all up before radioactive residues are flushed to the surface. It could take decades to resolve. In the meantime, excavations needed to extract the drums could cause new collapses and make the problem worse.3
Some 300,000 cubic metres of low and intermediate-level waste, including the waste dug from the Asse mine, is earmarked for final burial at the Konrad iron mine in Lower Saxony. But Germany still has no plan for dealing with high-level waste and spent fuel. Later this year, a Final Storage Commission of politicians and scientists will advise on criteria for choosing a site where deep burial or long-term storage should be under way by 2050.
But its own chairman, veteran parliamentarian Michael Muller, says that timetable is unlikely to be met. "We all believe deep geology is the best option, but I'm not sure if there is enough [public] trust to get the job done," he says. Many anti-nuclear groups are boycotting the Commission. The problems at the Asse salt mine have led to further distrust of engineers and their solutions.
The problems at Asse became public knowledge in 2008. Despite hurried backfilling of much of the mine, the degradation continues. Brine seeps in at a rate of around 12,000 litres a day, threatening to flush radioactive material to the surface. In 2011, the Federal Office for Radiation Protection (BfS) ruled that the waste had to be removed. But this is likely to take decades.
Just checking the state of the 13 chambers holding the waste drums is painfully slow. Engineers drilling to reach them through 20 metres of rock don't know whether the drums have leaked, and of course they cannot risk a release of radioactivity. And unless care is taken to keep clear of the geological barrier, the excavations risk allowing more water in, and flooding of the mine can't be ruled out.
Nothing will be moved until at least 2033. Meanwhile the bill keeps rising. It costs €140 million a year just to keep the mine safe for work to continue. The final bill will run into many billions. Is it worth it? Many experts fear that digging up the drums, with consequent risks of radioactive leaks, could create a much greater hazard than leaving them where they are.
Tunnel collapse and fatality at French repository site
Meanwhile one worker has been killed and another injured in a tunnel collapse at France's planned nuclear waste repository at Bure, in north-eastern France. According to French waste management agency Andra, geophysical surveys were being carried out at the time of the collapse and the rockfall is believed to have happened as drilling was taking place. Scheduled for an authorization decree in 2018 and industrial commissioning in 2025, the facility – if approved – is expected to bury France's highly-radioactive nuclear waste.4
Repository cost escalation in France
Reuters reported on January 12 that shares in French utility EDF sank to an all-time low after Andra said that the cost of a national nuclear waste repository for intermediate- and high-level waste could be higher than EDF's estimates. Andra says that costs for the deep geological storage project could range from €20 billion to €30 billion.5
French energy minister Ségolène Royal signed a decree setting the 'reference cost' for the repository at €25 billion. In 2005, Andra estimated the cost of the facility at between €13.5 and €16.5 billion. In 2009 Andra re-estimated the cost at around €36 billion. In a confidential 2014 file, which was recently leaked, Andra gave a cost estimate of €34.4 billion, based on 2012 prices, with construction accounting for 58% of the costs and operational costs over 100 years accounting for 26% of the total.6
EDF said that the new €25 billion reference cost will "substitute the estimated benchmark cost of €20.8 billion on which EDF Group relied in its consolidated financial statements at the end of December 2014 and at the end of June 2015". EDF said the increase in provisions will have a negative impact of around €500 million post-tax on net income group share in 2015.6
Reprinted from nuClear news with additions from Nuclear Monitor.
nuClear news, No.82, February 2016, www.no2nuclearpower.org.uk/nuclearnews/NuClearNewsNo82.pdf
1. Albuquerque Journal, 19 October 2015, www.abqjournal.com/661954/news/safety-top-dog-innew-wipp-culture.html
2. Stanford News, 15 Jan 2016, http://news.stanford.edu/news/2016/january/waste-nuclear-material-
011516.html and Nature 13 Jan 2016, www.nature.com/news/policy-reassess-new-mexico-snuclear-waste-repository...
3. New Scientist, 29 Jan 2016, www.newscientist.com/article/2075615-radioactive-wastedogs-germany-despi...
4. Cumbria Trust, 27 Jan 2016, https://cumbriatrust.wordpress.com/2016/01/27/at-least-1-killed-intunnel...
WNN, 26 Jan 2016, 'Fatal rockfall at planned French repository site', www.world-nuclear-news.org/RS-Fatal-landslide-at-planned-French-reposito...
5. Geert De Clercq, 12 Jan 2016, 'EDF sinks to all-time low as nuclear waste cost estimate soars', http://uk.reuters.com/article/edf-nuclear-waste-idUKL8N14W2RO20160112
6. World Nuclear News, 18 Jan 2016, 'Minister sets benchmark cost for French repository', www.world-nuclear-news.org/WR-Minister-sets-benchmark-cost-for-French-re...