DOE Considering Request for WTP LAW Facility Design Change
WC Monitor
9/5/2014
In a decision that could have significant schedule impacts for one of the main facilities to make up the Hanford Waste Treatment Plant, the Department of Energy is considering a request from contractor Bechtel National to move forward with a new safety system for the WTP Low Activity Waste Treatment Facility while at the same time performing required safety analyses, rather than first waiting for those analyses to be completed before proceeding with design and procurement of the new system. Bechtel National is looking to add a smoke detection system to the LAW Facility’s control system, known as the Programmable Protection System, to shut down the system in the event of smoke. “The PPJ halts feed to the melter and places the melter offgas system in a safe configuration during upset conditions. The vendor for the PPJ concluded that the outputs from the system are indeterminate when exposed to smoke,” states a Defense Nuclear Facilities Safety Board site representative report dated July 18.
The DNFSB site representative report goes on to state, “The contractor has proposed adding a safety-significant smoke detector system in the room that will isolate all power to the PPJ, thereby placing the offgas system in a configuration which they expect to be safe. However, they noted that simultaneously changing all the PPJ output signals may create additional problems.”
According to the DNFSB report, Bechtel has warned there could be significant delays to completing the LAW Facility if it has to wait until required safety analyses are completed before moving forward with design and procurement of the proposed smoke detection system. “The contractor claims the schedule for completing LAW construction would be substantially impacted if they have to delay the procurement of the smoke detection system until they complete the associated hazards analysis, control selections, and safety basis updates,” the report says. In a written response late this week, Bechtel National spokesman Todd Nelson said, “Using standard processes and procedures, BNI is evaluating the hazards of smoke to the Programmable Protection System (PPJ). BNI is proposing to complete the safety analyses while proceeding with the design and procurement of a smoke detection system. The request is being reviewed by the Department of Energy.”
The DOE Office of River Protection, which oversees the Hanford vit plant project, said this week that is still reviewing Bechtel National’s request, but did not provide a time frame in which a decision could be made. “The Department of Energy’s Office of River Protection (ORP) and Bechtel National, Inc. (BNI) are committed to completing the Low Activity Waste Facility in time to begin safe operations by December 2022. ORP is reviewing BNI’s proposal for the design of the smoke detection system for the Programmable Protection System,” DOE spokeswoman Lori Gamache said in a written response.
Monitoring Finds Low Level of Tank Vapors, DOE Says
WC Monitor
9/5/2014
A check of monitors worn by Hanford tank farm workers has found no samples with chemicals close to the federal limit for occupational exposure, according to the Department of Energy. However, there is the potential for reports of chemical vapors to increase with the planned startup on Sept. 5 of the 242-A Evaporator. Since spring, 44 workers have received medical evaluations for possible exposure to chemical vapors from the waste held in Hanford’s underground tanks. All have been cleared to return to work and a few of the potential exposures may have been linked to pesticide spraying rather than waste. “As far as we can tell there have not been any long-lasting health effects,” said JD Dowell, deputy manager of the DOE Office of River Protection, at a Hanford Advisory Board meeting late this week.
Some previous workers have reported serious long-term health effects from chemical vapor exposure and precautions have been taken since then, such as evacuating tank farms when vapors are suspected. An analysis of 3,200 samples collected by monitors worn by workers found 19 that showed chemicals present at more than 1 percent of the federal occupational exposure limit, Dowell said. The samples were collected from April 1 to July 7.
Washington River Protection Solutions uses an administrative limit for occupational exposure to chemicals that is 10 percent of the federal standard set by agencies such as the Occupational Safety and Health Administration, Dowell said. Four of the samples were above 10 percent of the federal limit, Dowell said. Those included samples with asbestos, mercury and nitrous oxide. There were no samples collected with chemicals at more than 50 percent of the federal occupational exposure limit, he said. However, DOE remains committed to a conservative response to chemical vapors and to protecting workers, he said. A draft report from an independent review led by the Savannah River National Laboratory to find solutions to chemical vapor issues is expected this month.
Extra Precautions Being Taken For When Evaporator Operates
The exposures to vapors are difficult to predict, Dowell said. They have been reported all over the tank farms and they do not necessarily correlate with conditions known to increase vapor releases from tanks, such as certain weather conditions and activities that disturb waste. Hanford officials do know that there is an increased propensity for vapors when the 242-A Evaporator is operating, Dowell said. It was last operated in fall 2010 and in the years since has been given an extensive overhaul. “We are taking special precautions to make sure workers are not exposed to vapors,” he said.
Employee parking is being restricted near the evaporator and monitors have been set up there to detect chemicals. Hand-held monitoring also is planned, and results will be posted daily. Masks will be available for workers who wish to wear them. Since waste will be transferred from nearby tanks to the evaporator and back again, there is potential for workers both in nearby tank farms and near the evaporator, to smell vapors. The most common chemical reported in tank vapors is ammonia, which can be smelled at low concentrations, workers have been told. Monitoring will be done for ammonia and other organic chemicals.
The evaporator reduces the amount of liquid waste held in double-shell tanks, creating more storage space for waste retrieved from leak-prone single-shell tanks. Hanford’s 28 double-shell tanks are nearing capacity and the planned evaporator campaign should reduce the waste volume by more than 1 million gallons, the equivalent of a full double-shell tank. A back-to-back evaporator campaign is planned with a first run removing about 800,000 gallons of liquid. The waste will be sent through the evaporator a second time to remove another 350,000 gallons of liquid. Work should be completed in mid-October.
DOE Completes Waste Retrieval from Two Single-Shell Tanks
WC Monitor
9/5/2014
Hanford workers have emptied waste to legal requirements from two more single-shell tanks, including the first tank emptied with the Mobile Arm Retrieval, or MARS, system. “MARS performed extremely well,” said Tom Fletcher, the Department of Energy’s assistant manager of the Hanford tank farms. They are the first two tanks declared emptied to regulatory requirements this calendar year and bring the total of tanks considered empty to 13 of 149 single-shell waste tanks. However, DOE still looks to fall short of a court-enforced consent decree requirement to have all 16 tanks in the C Tank Farm emptied of waste by the end of September. All but one of the emptied tanks are in the C Tank Farm, bringing the total emptied there to 12, with four more to go. DOE earlier notified the state of Washington that it was a risk of not having all of the C Farm tanks emptied by the end of Fiscal Year 2014, and negotiations are underway between DOE and the state on possible revisions to consent decree requirements on emptying tanks and the Waste Treatment Plant being built to treat the waste for disposal.
Hanford tank farms contractor Washington River Protection Solutions had proposed a larger and more robust system to empty waste from underground tanks when it won the tank farm contract and started work at Hanford nearly six years ago. In the past, systems to empty the tanks had to fit down 12-inch diameter risers, which extend from the ground into the enclosed, underground tanks. But WRPS used remotely operated equipment to cut a 55-inch hole into the top of Tank C-107 and then installed a 42-inch riser, showing that opening a high-level radioactive waste tank could be carefully done without harming workers or the environment. The larger riser allowed a larger and more powerful robotic arm equipped with multiple technologies to be inserted into the tank to remove waste. The MARS robotic arm can be raised or lowered in the tank, rotated 360 degrees and unfolded and lengthened to reach 40 feet to the tank sides or bottom. The operating head, with multiple low- and high-pressure spray nozzles, is articulating, allowing it to reach around obstructions encountered in the tank.
MARS Began Work in 2011
The use of MARS was considered a demonstration project and it began removing waste in fall 2011. Since then, its operation has been shut down multiple times, but mostly because of issues unrelated to MARS, including equipment problems at the double-shell tank used to receive waste from Tank C-107. Equipment can deteriorate quickly in the harsh environment of radioactive waste. The first technology used by MARS in Tank C-107, which held 253,000 gallons of waste after pumpable liquids were removed, was a sluicing system. It sprayed liquid waste on the sludge in the tank to break it up and move it toward a pump for removal. It was able to remove about 90 percent of the waste in the tank.
Then MARS used high pressure liquid to attack the hard waste beneath the sludge. However, that stopped being effective with about 7 percent of the waste in the tank remaining. Hard chunks of waste at the bottom of the tank were too large to be pumped out and a “bathtub ring” remained of hard, crusted waste on the tank’s wall. Hot water was used next to dissolve waste that had high levels of phosphates.
The goal was to have 2,700 gallons or less of waste remaining in the tank, which amounts to about one inch of waste if it were spread evenly over the bottom of the tank. However, the consent decree also allows a tank to be considered emptied to regulatory standards if three technologies have been used to remove as much waste as possible. In the case of Tank C-107, about 12,000 gallons of waste remains after three technologies were used. “MARS has retrieved all the mobile components of the waste,” Fletcher said. The remaining waste is too hard to break up or in chunks that cannot be pumped out. Before the tank is closed in a future step of cleanup, the remaining waste will be analyzed to make sure that the closure is protective of human health and the environment.
Tank C-101 Has Approx. 5,000 Gallons of Waste Remaining
The second tank now considered retrieved to regulatory standards is Tank C-101, which has about 5,000 gallons left in it after two technologies were used to remove waste. The tank had 77,500 gallons of solid waste when work to retrieve the waste started in December 2012. Hanford workers used a telescoping sluicing system and then a high-pressure spray as a second waste-retrieval technology. DOE asked the state to approve the tank as meeting the consent-decree requirements for waste retrieval, believing that it did not have a third technology that would substantially reduce the risk from the remaining waste in the tank. The state recently agreed, according to DOE. Waste now is being emptied from Tank C-105 using a MARS system. It is the second Hanford tank that has had a larger riser installed. The MARS system being used in Tank C-105 is equipped with a vacuum, rather than a sluicing, system because the tank may have leaked waste in the past.
