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DNFSB spots possible bottleneck in Hanford’s waste vitrification
Workers change out spent 27,000-pound TSCR filter columns and place them on a nearby storage pad during a planned outage in 2023. (Photo: DOE)
While the Department of Energy recently celebrated the beginning of hot commissioning of the Hanford Site’s Waste Treatment and Immobilization Plant (WTP), which has begun immobilizing the site’s radioactive tank waste in glass through vitrification, the Defense Nuclear Facilities Safety Board has reported a possible bottleneck in waste processing. According to the DNFSB, unless current systems run efficiently, the issue could result in the interruption of operations at the WTP’s Low-Activity Waste Facility, where waste vitrification takes place.
During operations, the LAW Facility will process an average of 5,300 gallons of tank waste per day, according to Bechtel, the contractor leading design, construction, and commissioning of the WTP. That waste is piped to the facility after being treated by Hanford’s Tanks Side Cesium Removal (TSCR) system, which filters undissolved solid material and removes cesium from liquid waste.
According to a November 7 activity report by the DNFSB, the TSCR system may not be able to produce waste feed fast enough to keep up with the LAW Facility’s vitrification rate.
Rahim Nabbi
Nuclear Technology | Volume 64 | Number 1 | January 1984 | Pages 5-13
Technical Paper | Nuclear Safety | doi.org/10.13182/NT84-A33321
Articles are hosted by Taylor and Francis Online.
The core dynamic analysis of an anticipated heat removal transient without scram in a high-temperature gas-cooled reactor has indicated that in case of a failure of core cooling, the reactor undergoes a selfshutdown after 1 min because of its negative temperature coefficients of reactivity. If the decay heat removal system operates according to plant specification, recriticality, and thus nuclear power generation, occurs. However, the maximum rise in fuel elements temperature is limited to 50°C due to the high heat capacity of the core. Without taking into consideration the effect of xenon feedback on the neutron kinetics, a new steady core state is established after 2 h in which the fuel temperature and gas outlet temperature at the lower core edge are 195°C higher than in normal operation. Due to transient xenon poisoning, a rise in gas outlet temperature only occurs during the first 70 min and amounts to 70°C. For this reason undesirable transient strains on the components connected behind the core are not expected. A slow xenon buildup during the first hour ensures a long-term subcriticality of the reactor. Without any contribution from the shutdown system, this leads to a decrease in nuclear power and thus to core cooling with functioning decay heat removal.