Progress for WIPP infrastructure upgrade

17 May 2018

The US Department of Energy has approved the start of construction of a new underground ventilation system at the Waste Isolation Pilot Plant (WIPP) in New Mexico. The USD288 million Safety Significant Confinement Ventilation System (SSCVS) is one of a number of infrastructure projects planned for the New Mexico facility.

Mining activities at WIPP currently take place on separate shifts to emplacement activities, to ensure sufficient airflow (Image: DOE Office of Environmental Management)

The start of construction was approved on 14 May by Assistant Secretary for Environmental Management Anne White, who said it would be a "significant improvement" for WIPP. The SSCVS is described as key to DOE plans to increase shipments of waste to WIPP from clean-up sites across its complex.

The new system will significantly increase the amount of air available to the underground portion of the WIPP facility, where sealed drums of transuranic - or TRU - wastes from the US military programme are placed in underground rooms mined out of an ancient salt formation. The increased ventilation will allow waste emplacement activities to be performed at the same time as facility mining and maintenance operations. It will also allow for easier filter replacement and preventative maintenance activities, the DOE Office of Environmental Management said.

Operations at WIPP were suspended in February 2014 following a fire in an underground vehicle and, several days later, a non-related radiological event when a waste drum ruptured following an exothermic chemical reaction in organic absorbent material used in the drum to stabilise liquids and nitrate salts. Following a stepwise recovery plan estimated to cost USD242 million up to the restart of operations, waste emplacement resumed in January 2017 with waste that had been stored at an on-site facility. Shipments of waste to the facility began in April 2017, and mining operations in January this year.

Installation of a new permanent ventilation system - the SSCVS - as well as a new exhaust shaft were identified as further infrastructure developments to be implemented after the resumption of WIPP operations.

The SSCVS will replace WIPP's existing underground ventilation system, which has since 2014 operated in filtration mode with all exhaust directed through above-ground high-efficiency particulate air filter units. This results in a lower airflow than without filtration, and in March this year WIPP management and operations contractor Nuclear Waste Partnership introduced a schedule with mining and waste emplacement conducted on separate shifts, to ensure sufficient underground airflow for worker safety. Mining activities take place during the day, with emplacement on the "back shift" so there is no competition for airflow.The SSCVS, which will provide pathways for both filtered and unfiltered air, will address this problem.

WIPP is the USA's only repository for the disposal of TRU waste which includes clothing, tools, rags, residues, debris, soil and other items contaminated with small amounts of plutonium and other man-made radioactive elements from the US military programme. Disposal of TRU waste is critical to the clean-up of Cold War nuclear production sites. US Energy Secretary Rick Perry has also recently confirmed that 34 tonnes of weapons-grade plutonium will now be diluted and disposed of at WIPP rather than converting to MOX fuel as previously planned.

The SSCVS is due to be completed in by early 2021.

Researched and written
by World Nuclear News