Structural integrity assessments for the category C liquid low-level waste tank systems at the Oak Ridge National Laboratory

Abstract

This document provides a report of the efforts made to satisfy the Federal Facility Agreement (FFA) for the structural integrity certification of 14 Category C Liquid Low Level Waste (LLLW) Tank Systems on the Oak Ridge Reservation (ORR) in Oak Ridge, Tennessee. Within this document, each tank system is described including the associated pipeline segments evaluated as a part of those tank systems. A separate structural integrity assessment was conducted for each of the LLLW Tank Systems, four of which are located in Melton Valley, and ten of which are located in Bethel Valley. The results of the structural integrity assessments are reported herein. The assessments are based on (1) a review of available tank design drawings, (2) a qualitative assessment of corrosion on the tank and pipelines, and primarily, and (3) leak testing program results. Design plans and specifications were reviewed for a general description of the tanks and associated pipelines. Information of primary significance included tank age, material of construction, tank design and construction specifications. Design plans were also reviewed for the layouts and materials of pipeline constructions, and ages of pipelines. Next, a generic corrosion assessment was conducted for each tank system. Information was gathered, when available, related to the historical use of the tank and the likely contents. The corrosion assessments included a qualitative evaluation of the walls of each tank and pipelines associated with each tank, as well as the welds and joints of the systems. A general discussion of the stainless steel types encountered is included in Section 4.0 of this report. The potential for soils to have caused corrosion is also evaluated within the sections on the individual tank systems.