DESIGNING AND CONSTRUCTING HANFORD'S WASTE TREATMENT PLANT - CHALLENGES AND PROGRESS IN THE NATION’S LARGEST CONSTRUCTION PROJECT

摘要

There are many challenges in the design and construction of the Department of Energy’s (DOE’s) $5.7 billion Hanford Tank Waste Treatment and Immobilization Plant (WTP) that is rising above ground at the Hanford site. Being built to process radioactive waste from cold war plutonium production operations contained in 177 underground tanks, engineering is about 85% and construction is at about 45% complete. The project, comprised of 3 large process buildings - the Pretreatment (PT) facility, High Level Waste (HLW) facility, and Low Active Waste (LAW) facility, is scheduled to complete construction in 2008 and hot commissioning in early 2011. Design challenges have included staffing for and performing extensive design for a closecoupled design/construction project, completion of the process design with a large confirmatory testing program, and the successful employment of the “black cell” design approach involving operating spaces for which no entry in a process cell is presumed in 40 years of plant operation. Construction on the 57-acre site started with first concrete in July 2002. Ultimately some 250,000 cubic yards of concrete with 40,000 tons of rebar and 27,000 tons of embeds will be placed and 200 miles of mostly small-bore piping will be installed in the three facilities [1]. A key construction hurdle is installing the mazes of piping associated with the process vessels. Many vessels have 30 to 40 piping penetrations on the head, creating very congested areas for installation and inspection and the need to use advanced examination techniques. Other challenges specific in the PT facility include proving that the resin used in the crucial cesium ion exchange process will perform adequately, use of fluidic pulse jet mixers (PJMs) on high rheology non-Newtonian wastes, and the precision installation of remote jumpered equipment in the hot cell. In LAW, the fabrication and installation of the huge melters is a challenge, and in HLW the design and testing of the remotely operated and maintained melters is a key challenge.