On Feb. 14, radioactive material leaked from the Waste Isolation Pilot Plant nuclear waste repository in New Mexico. Reports about the incident appear to be pointing a finger at a reactive mixture of nitrate salts and organic material in the waste drum involved–and more may have the same problem.
There are some details of the incident in a Department of Energy “Waste Isolation Pilot Plant Nitrate Salt Bearing Waste Container Isolation Plan” dated May 30:
• The event did not appear to involve an explosion.
• A chemical reaction in the involved container created sufficient heat to breach the lid to the container and caused a release.
• Damage to surrounding containers, backfill bags, shrink-wrap, and slip-sheets was due to the heat.
• The bulkhead adjacent to the waste stack in Panel 7, Room 7 does not appear to display signs of pressure.
• The risk to workers is from heat, smoke, airborne radionuclides, and pressure related to container(s) breaching.
The nuclear waste material itself was nitrate salts. The organic material was added in processing and packaging the waste and comes from two sources. One was the use of cat litter added as a sorbent. Formerly a clay material, at some point Los Alamos National Laboratory changed to a cellulose material.
The other was neutralizers added to adjust the pH of the material. According to a document by contractor EnergySolutions, this is what went into the drums:
- Prior to September, 2013: Chemtex Acid Neutralizer, dry formula; contains “polymer,” sodium carbonate, alizarin (pH indicator)
- After September, 2013: Spilfyter Kolorsafe Acid Neutralizer, liquid formula; contains triethanolamine, alizarin, water
- Before April, 2013: Spilfyter Kolorsafe Benchtop Kits; contains citric acid, thymol blue (pH indicator); MSDS notes that the material is incompatible with metallic nitrates and strong oxidizers
- After April, 2013: Pig Base Encapsulating Neutralizer, dry formula; contains citric acid, “super absorbent,” thymol; MSDS notes that the material is incompatible with metallic nitrates and strong oxidizers
The New Mexico Environment Department so far seems concerned about the cat litter, but the base neutralizer clearly presented a problem as well. The plan right now seems to be to seal the rooms containing concerning drums as quickly as possible. There are more sitting at LANL waiting to be moved to the pilot plant as well as a site in West Texas.
More documents are available at the New Mexico Environment Department website.
Albuquerque Journal: WIPP probe: Emails raise new questions, Photos show cracked LANL container at WIPP
Forbes: Response to nuclear kitty litter is moving fast
NPR: Organic cat litter chief suspect in nuclear waste accident
Nature: Nuclear-waste facility on high alert over risk of new explosions, Call for better oversight of nuclear-waste storage