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Title: 99Tc Process Monitoring System In-Lab Performance Characterization

Executive Summary A 99Tc Process Monitoring (Tc-Mon) System has been designed and built for deployment at the recently constructed 200 West Pump & Treat (200W P&T) Plant in the 200 West Area ZP-1 Operable Unit of the Hanford Site. The plant is operated by CH2M Hill Plateau Remediation Company (CHPRC). The Tc-Mon system was created through collaboration between Pacific Northwest National Laboratory (PNNL) and Burge Environmental, Inc. The new system’s design has been optimized based on experience from an earlier field test (2011) of a prototype system at the 200W-ZP-1 Interim Pump & Treat Plant. A portion of the new 200W P&T Plant is dedicated to removal of 99Tc from contaminated groundwater in the 200 West Area. 99Tc, as the pertechnetate anion (99TcO4-), is remediated through delivery of water into two trains (Trains A and B) of three tandem extraction columns filled with Purolite A530E resin. The resin columns cannot be regenerated; therefore, once they have reached their maximum useful capacity, the columns must be disposed of as radioactive waste. The Tc-Mon system’s primary duty will be to periodically sample and analyze the effluents from each of the two primary extraction columns to determine 99Tc breakthrough. The Tc-Mon system willmore » enable the CH2M Hill Plateau Remediation Company (CHPRC) to measure primary extraction column breakthrough on demand. In this manner, CHPRC will be able to utilize each extraction column to its maximum capacity. This will significantly reduce column disposal and replacement costs over the life of the plant. The Tc-Mon system was constructed by Burge Environmental, Inc. and was delivered to PNNL in June 2013 for setup and initial hardware and software performance testing in the 325 Building. By early July, PNNL had initiated an in-laboratory performance characterization study on the system. The objective was to fully calibrate the system and then evaluate the quality of the analytical outputs 1) against a series of clean groundwater samples prepared as 99Tc standards, and 2) on actual 200W P&T Plant grab samples containing 99Tc (and other radioactive and non-radioactive contaminants) at levels reported by the Waste Sampling and Characterization Facility. These grab samples included pre-treated (Pre-Resin) and post-treated (Post-Resin) 200W P&T Plant waters for May through August 2013. This report contains the following information: • The genesis of the 99Tc sensor and the Tc-Mon analytical system. • A description of the Tc-Mon system’s major hardware and software components. • A description of the operational principles behind the 99Tc sensor. • Results from the calibration of three components within the Tc-Mon system. The three systems requiring calibration are: 1. Sampling Chamber 2. Conductivity Sensor 3. 99Tc Sensor • Presentation of analytical results obtained on the fully calibrated Tc-Mon system. This includes a determination of the precision and accuracy of each system defined above. • Estimation of the 99Tc sensor’s minimum detectable activity and limit of quantification. • A brief discussion of potential chemical and radiological influences on the 99Tc sensor based on known contaminants in 200W P&T Plant water. • Observations regarding 99Tc sensor longevity.« less
Publication Date:
OSTI Identifier:
Report Number(s):
PNNL-23131; RPT-DVZ-AFRI-015
DOE Contract Number:
Resource Type:
Technical Report
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
Country of Publication:
United States
process monitor; pump and treat; sensor; radiochemical; technetium; groundwater