Recently, the only transuranic waste disposal facility in the United States, the Waste Isolation Pilot Plant (WIPP), announced that its new large-scale ventilation system has been fully debugged and is expected to be fully operational within the year. The key component of this ventilation system, the high-efficiency particulate air (HEPA) filtration device, has attracted much attention and become a core element in ensuring the air quality and surrounding environmental safety of underground disposal facilities.
The Safety Critical Closed Ventilation System (SSCVS) is one of the major projects launched by the Office of Environmental Management of the US Department of Energy to significantly increase the underground ventilation capacity of the WIPP disposal facility. Its aim is to synchronize the disposal of sealed waste bins in underground salt layer disposal rooms with facility excavation and maintenance operations. The ventilation system will work in conjunction with the newly built public shaft, and its workflow is to extract air from the underground disposal facility, remove salt if necessary, and purify it through HEPA filtration devices before discharging it into the environment.
HEPA filter, as a mechanical air filter, can remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles not less than 0.3 microns. This characteristic is crucial for the environment of transuranium waste disposal facilities, as it can effectively prevent radioactive particles and harmful pollutants from underground disposal facilities from spreading to the external environment, protecting the health and ecological safety of surrounding residents.
SSCVS consists of two main buildings: the salt reduction building is used for pre filtering salt laden air from underground disposal facilities; The new filtering building is equipped with built-in fans and 22 sets of HEPA filtration units. The construction of the new system significantly increases the underground ventilation volume from the current 170000 cubic feet per minute (approximately 4814 cubic meters per minute) to a maximum of 540000 cubic feet per minute (approximately 15290 cubic meters per minute), significantly enhancing ventilation capacity and reducing the risk of pollution in underground spaces.
During the debugging phase, the management and operation contractor of the waste isolation pilot plant, Salado Isolation Mining Contractors, conducted individual tests on each subsystem, followed by overall testing of the entire SSCVS to verify its complete functionality. At present, the commissioning work has been successfully completed, and the SSCVS has been handed over to the operation team so that they can master the operation of this efficient system. Subsequently, relevant departments will conduct an evaluation to demonstrate that SSCVS has been fully integrated into other systems of the waste isolation pilot plant, ensuring that all main and backup systems are operating as expected and that operators are proficient in system operation. After all review work is completed and approved by the US Department of Energy's Office of Environmental Management, the SSCVS will be connected to the underground ventilation system of the disposal facility.
The construction of the ventilation system began in 2018, with an initial estimated cost of 288 million US dollars, and is scheduled to be completed in November 2022. However, affected by the COVID-19, similar to most sites of the Environmental Management Office of the Ministry of Energy, the waste isolation pilot plant once only maintained the operation of key tasks, leading to the delay of project progress. According to a report released by the US Government Accountability Office last year, the estimated project cost has increased to $494 million by 2024.
The waste isolation pilot plant is located in a natural salt rock formation 650 meters underground and has been in operation since 1999. It is the only transuranic (TRU) waste disposal facility in the United States. This type of waste includes clothing, tools, fabrics, residues, debris, soil, and other items contaminated with plutonium and other artificial radioactive elements in US military programs. The implementation of the new ventilation system will further enhance the operational safety and environmental protection level of the WIPP disposal facility, providing a more solid guarantee for the safe disposal of transuranium waste.