BGRR Below-Ground Primary Liner Cleanup

February 2004

BGRR Below-Ground Primary Liner Cleanup

BROKK machine picking up liner pieces

Background

The Brookhaven Graphite Research Reactor (BGRR) decommissioning project was divided into seven sub-projects as a result of the BGRR Decommissioning Project Removal Action Alternatives Study, January 2000. The projects were scheduled beginning with the easiest and moved to the more difficult, and from the items taking the least time to complete to those that would require more time to plan and execute. This action was part of sub-project Step 5.

Most of the BGRR cleanup projects took place under federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Removal Actions. These are cleanups where known contamination is dealt with as quickly as possible to remove the potential for it to affect human health or the environment, in the absence of a Record of Decision (ROD). A ROD is a CERCLA decision document that requires more detailed and time-consuming characterization and analysis of contamination sources and possible cleanup options. The BGRR ROD was finalized in 2005.

History

The BGRR operated from 1950 until 1968. It was fueled with natural uranium until 1958 and enriched uranium until it was shutdown. There were 28 ruptured fuel cartridges reported during the lifetime of the reactor. These fuel failures led to the contamination of the cooling system and its components, including the primary liner of the below-ground ducts.

The primary liner was located inside the below-ground ducts. There were two ducts, north and south, and each contained a primary liner. To protect the concrete of the ducts from the high exhaust air temperatures during reactor operations, the duct section upstream of the air coolers had a three-part thermal liner which was called the primary liner and a secondary liner. The secondary liner formed the inner wall of the concrete duct and was bonded to the concrete with steel J-bolts. A three-inch space between the primary and secondary liners formed the secondary air duct; the inner duct was the primary air duct. During reactor operations, the primary reactor cooling air flowed through the primary air duct and secondary cooling air flowed through the three-inch secondary duct to cool the concrete duct structure.

Video inspections showed water marks at several locations inside the primary liner and a gas-tracer leak test in early 2001 demonstrated that the ducts leaked contaminated water to the surrounding soils.

Description of Removal Action

The BGRR's exhaust filters and contaminated portions of the below-ground air duct liner were removed in 2004 using a remotely operated robot know as a BROKK manipulator. This project was a major radiological challenge and demonstrated the use of innovative technologies that minimized worker exposure and allowed safe completion of the project. The internal surfaces of the duck work, air filters, and portions of the Instrument House, Bldg. 708, were contaminated with fission products such as cesium-137, strontium-90, cobalt-60, uranium, and plutonium.

The primary liner for both the north and south ducts was removed from the reactor exhaust air plenums, where the duct transitions from vertical to horizontal, to the liners termination at the location of the previously removed air coolers. In all, nearly 500 feet of liner was removed. An estimated 700,000 pounds of debris was removed and shipped off-site for disposal.

Following completion of the primary liner removal in January 2005, contaminated soil was removed from beneath the south below-ground duct expansion joint. Plates were installed in the duct to isolate it from the secondary air system; loose concrete at the wall/floor joint was removed and the cracks were sealed. Approximately 200 gallons of standing water was removed from the deep drain sump and the plenum drain lines. The water was solidified and disposed of in accordance with the below-ground duct liner removal Waste Management Plan. After removing any loose debris, the drain lines and deep drain sump were filled with a cementious grout. Two cubic yards of contaminated soil was removed from beneath expansion joint #4.

Community Outreach

There were numerous opportunities provided for stakeholders to provide input. As with previous Removal Actions, the Roundtable meetings held in 1999 helped to determine the extent of the BGRR cleanup activities. Additional input was received on the Decommissioning Project Removal Action Alternatives Study during the public comment period held from January 20 through February 28, 2000 and the two information meetings held on February 1 and 26, 2000.

The Lab's Community Advisory Council and Brookhaven Executive Roundtable were kept up-to-date with briefings on the progress of all the projects at the BGRR. Weekly status reports were posted on the BGRR web pages so that interested readers could follow the progress of the project. Additionally, a public notice was published in regional newspapers upon issuance of the Removal Action memorandum.