A biological shield, center, surrounds the core of the tank-type reactor in which primary coolant was used for cooling the reactor’s core. Photo by LeRoy N. Sanchez, Public Affairs
The Laboratory in June plans to begin decommissioning and demolishing the Omega West Reactor. The project is scheduled to be completed in September 2003. The Omega West Reactor is located at Technical Area 2 in Los Alamos Canyon and TA-61 on the south mesa of the canyon. The Cerro Grande Rehabilitation (FWO-CGRP) Project Office is leading this project, having developed the contract that incorporates requirements and high incentives for waste minimization in recovery of the Cerro Grande Fire.
"This project is slated to be yearlong because of the complexity of the job. We also must ensure that the work is performed safely and that there are no environmental impacts," said Keith Rendell of Construction and Facility Services (FWO-CFS).
The history of the OWR is as long as it is varied. The reactor was completed in 1956 and operated eight hours a day, five days a week, at a power level of eight megawatts thermal.Donald W. Barr of Isotope and Nuclear Chemistry (C-INC) said, "The reactor's original purpose in 1956 was for conducting nuclear research by collecting nuclear data of isotopic species in support of the weapons program." Barr was a staff member that used the facility when the reactor first became operational.
Cherenkov radiation, when it is intense, appears as a weak bluish-white glow in the pools of water shielding the nuclear reactor. The Cherenkov radiation is caused by electrons from the reactor traveling at speeds greater than the speed of light in water, which is 75 percent of the speed of light in a vacuum. Photo by Jose “Mitzie” Ulibarri, former Information Services (IS-7)
The Omega West Reactor and several other structures are located in a flood plain; the project will focus on reducing the potential for radioactive contamination to spread in the event of a flash flood. Removal of the buildings eliminates the potential risk of contamination to the water and land should a catastrophe occur, added Rendell. Rendell said the subcontractor company that wins the bid "must adhere to the Lab's decommissioning and demolition health and safety plan by submitting a specific health and safety plan to cover both the workers and the environment."
Decommissioning and demolition involves disposing of all waste, including radioactive and hazardous waste. "The waste is segregated, classified and disposed of properly by the subcontractor with 80 percent sent to a treatment storage facility," explained Rendell. The subcontractor also must strive to meet requirements for the recycling of at least 18 percent of all materials removed from the site. The waste includes wood, concrete, iron, steel and glass.
During the 1960s-70s, the reactor also was used for neutron activation analysis to determine elemental compositions of solids, said Gene Peterson of Actinide, Catalysis and Seperations Chemistry (C-SIC). Peterson was group leader of Medical Radioisotope and Reactor Applications as well as program manager for Isotope Production and Distribution in 1993.
According to Peterson in the late 1980s alternative funding sources were needed for the continuation of the reactor, so the U.S. radio pharmaceutical industry petitioned the Department of Energy to use the Omega West Reactor as a possible production source of Molybdenum-99. "About 85 percent of all medical isotopes used for imaging and treatment are derived from Molybdenum-99. We expected to produce approximately 30 percent of the U.S. demand for Molybdenum-99 starting in 1993," he said.
The reactor has not operated since December 1992. Peterson said an operator error caused the reactor to power up beyond normal limits, causing the system to shut down automatically. During the course of an investigation of the incident, the reactor was shut down. During the shutdown, operators noticed that the reactor was leaking tritium contaminated primary coolant water into the ground. The coolant leak was found in a 30-inch diameter pipe buried underground. The source of the leak was a delay line that was later fully excavated. The Laboratory found that the 70-foot-long pipe underwent stress corrosion cracking, which was enhanced by a bacterial action. No subsequent leaks were found after metallurgical tests were conducted. Although the cooling system could have been repaired, DOE decided to permanently shut down the reactor. The reactor's fuel rods were removed in 1994, allowing the reactor to be placed in a safe shutdown mode.
Peterson said, "I always enjoyed being associated with the OWR, and I felt good that I could help to develop a future mission for the medical isotope program. However, I'm still disappointed that we didn't take the Molybdenum-99 project at the reactor to a successful conclusion."