The first three technical issues that have prevented construction on key parts of the Hanford Site’s Waste Treatment Plant since 2012 have been resolved, according to the Department of Energy. Work continues on five additional technical issues identified after then-Energy Secretary Steven Chu directed an in-depth look in 2012 at possible problems at the plant. But the three resolved matter “are certainly the three toughest technical issues,” said Bill Hamel, DOE assistant manager for the Hanford vitrification plant project.
Resolution means that and engineering work may resume on the Pretreatment Facility for the vit plant, which contractor Bechtel National is building at to process up to 56 million gallons of chemical and radioactive waste stored at the DOE site in Washington state. However, construction will not resume until issues are considered closed at the conclusion of the design and engineering work.
The five remaining technical issues are expected to be resolved by the end of 2018, but DOE has not released an estimated date for resumption of construction. Construction halted on the Pretreatment Facility and part of the High-Level Waste Facility due to issues related to high-level radioactive waste. Design and engineering on the High-Level Waste Facility resumed in 2014.
Issues resolved at the Pretreatment Facility are the potential accumulation of hydrogen in the building’s process tanks; the potential for hydrogen accumulation in pipes and nonprocess tanks; and the potential for a nuclear criticality in process tanks. Criticalities could occur if sufficient large, heavy particles of plutonium settled out of waste in processing tanks. The proposed solution would involve blending or diluting the waste feed to reduce the amount of large plutonium particles in each process batch.
Hydrogen accumulation in the head space of Pretreatment Facility process tanks is proposed to be cleared by periodic ventilation. A revised process-tank design would have a smaller head space so less hydrogen could accumulate and the air volume could be turned over more quickly. Hydrogen accumulation in tanks would be addressed by eliminating some high points in piping where hydrogen might accumulate and adding vents to piping where needed.
