Analysis of Soluble Re Concentrations in Refractory from Bulk Vitrification Full-Scale Test 38B

Cooley, Scott K. ; Pierce, Eric M. ; Bagaasen, Larry M. ; Schweiger, Michael J.

Pacific Northwest National Laboratory (U.S.)

关键词: Heating;    Capacity;    Waste Forms;    Waste Processing;    Tanks;   

DOI  :  10.2172/890728
RP-ID  :  PNNL-15868
RP-ID  :  AC05-76RL01830
RP-ID  :  890728

美国|英语

来源: UNT Digital Library

【 摘 要 】

The capacity of the waste treatment plant (WTP) being built at the Hanford Site is not sufficient to process all of the tank waste accumulated from more than 40 years of nuclear materials production. Bulk vitrification can accelerate tank waste treatment by providing some supplemental low-activity waste (LAW) treatment capacity. Bulk vitrification combines LAW and glass-forming chemicals in a large metal container and melts the contents using electrical resistance heating. A castable refractory block (CRB) is used along with sand to insulate the container from the heat generated while melting the contents into a glass waste form. This report describes engineering-scale (ES) and full-scale (FS) tests that have been conducted. Several ES tests showed that a small fraction of soluble Tc moves in the CRB and results in a groundwater peak different than WTP glass. The total soluble Tc-99 fraction in the FS CRB is expected to be different than that determined in the ES tests, but until FS test results are available, the best-estimate soluble Tc-99 fraction from the ES tests has been used as a conservative estimate. The first FS test results are from cold simulant tests that have been spiked with Re. An estimated scale-up factor extrapolates the Tc-99 data collected at the ES to the FS bulk vitrification waste package. Test FS-38A tested the refractory design and did not have a Re spike. Samples were taken and analyzed to help determine Re CRB background concentrations using a Re-spiked, six-tank composite simulant mixed with soil and glass formers to produce the waste feed. Although this feed is not physically the same as the Demonstration Bulk Vitrification System feed , the chemical make-up is the same. Extensive sampling of the CRB was planned, but difficulties with the test prevented completion of a full box. An abbreviated plan is described that looks at duplicate samples taken from refractory archive sections, a lower wall sample, and two base samples to gain early information about Re and projected Tc-99 levels in the FS box.