New methods for determination of interstitial liquid levels in Hanford waste tanks

摘要

The key to the leak detection program for many tanks at Hanford is the method used to evaluate the apparent interstitial liquid interface (ILL) within the pore space of the solid waste medium (either crystalline or sludge). Three new approaches were introduced in the summer of 1993 (count rate, derivative, and sigmoid), all of which significantly improved the accuracy and repeatability of interstitial liquid level values from neutron survey data. This paper summarizes the three new methods and details a case study in which, as a direct result of this improved analysis, a tank that had been declared an ''assumed leaker'' was reclassified as ''sound'' for the first time in Hanford's 50 year history.