The Department of Energy has uncovered technical findings in the vitrification plant's proposed design at a nearly constant rate since 2008, according to Gary Brunson, plant engineering division director for DOE.
"The number and rate of problems identified is indicative that issues are not being resolved," he wrote in a memo.
He listed 34 examples, detailing some of his concerns that he said DOE engineering staff have worked to have corrected, as follows:
-- Contractor Bechtel National said the process offgas from some of the melters turning radioactive waste into glass should be under positive pressure.
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That means any pinhole leak would result in fatal concentrations of gases in a matter of seconds for nearby people. Bechtel said it could manage or seal 560 potential leak sites, according to Brunson. The design has since been changed to put much of the system under a vacuum.
-- Bechtel advised that melters can be purged of high-level radioactive waste glass before disposal using a vacuum system. However, the melters are in an area that is sealed and have no space for a vacuum system to be installed, according to Brunson.
-- Bechtel previously found pitting in buried piping because of defects but recommended no further look at the extent of conditions when additional corrosion was found in buried piping for ammonia, which could be important to safety, according to Brunson.
-- Bechtel said gas powered turbine generators could be used instead of diesel for nuclear emergency power application, but turbine generators have a longer start time, requiring re-evaluation for safety scenarios, according to Brunson.
-- Bechtel designed the return line for steam condensate so that it went directly from the Pretreatment Facility reboilers, which are used to heat contaminated fluids, to support facilities where no work with radiological waste is planned. A tiny leak could result in contamination to those facilities and occupied areas, according to Brunson. A secondary closed loop system has since been designed.