A take cover order that lasted about four hours has been lifted for Hanford nuclear reservation workers.
At least 500 workers were ordered to take cover indoors Friday morning in an area near the center of the 580-square-mile federal site north of Richland.
A take cover order that lasted about four hours has been lifted for workers at the 200 East Area in central Hanford.
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A team surveyed the area where steam had unexpectedly been spotted coming from a building at one end of a tunnel storing radioactive waste shortly before 6 a.m.
No evidence was found that any radioactive particles had escaped the tunnel to contaminate the air.
Lights and cameras already placed in the tunnel showed steam in its interior as the latest layer of concrete-like grout poured inside the tunnel cured. The curing process generates heat and moisture.
When the warm air left the tunnel and hit the cool morning air, steam was visible, according to the Department of Energy.
Workers were ordered, as a precaution, to take cover indoors with windows and doors closed and ventilation systems shut down. They also were prohibited from eating and drinking for much of the take cover alert.
Most of the workers will be returning to their planned work tasks this afternoon, but work to grout the tunnel likely will be paused for a few days, according to the Department of Energy.
Over the next few days, crews will evaluate the opening in the building where steam escaped. The building had previously been sealed up. It was original to the tunnel, with construction completed in 1964.
Then work to stabilize the tunnel by filling it with grout is expected to resume.
Since the first of the month when grouting began, workers have placed about 9,000 cubic yards of grout in the tunnel in thin layers. It is estimated to be almost 25 percent of the grout that will be needed to fill the tunnel to prevent a possible collapse.
Hanford officials are waiting for results of radiological surveys being done at the PUREX plant’s second radioactive waste storage tunnel.
Steam was spotted coming from a small building at one end of the tunnel early Friday morning.
There have been no reports of airborne radioactive particles at this time.
Workers continue to report to work in areas outside the 200 East Area in central Hanford, where the unexpected steam was reported.
They are asked to avoid the Wye Barricade secure entrance to the site just north of Richland and enter the site through the Rattlesnake Barricade off Highway 240.
A crew has entered the work area where steam was spotted coming from a small building at one end of the PUREX radioactive waste storage tunnel.
The crew has begun radiological surveys. No airborne release of radiological material has been reported at this time, but central Hanford workers remain under a take cover order as a precaution.
Some steam was expected as concrete-like grout has been injected into the tunnel in layers since the start of the month. It heats up as it cures, according to the Department of Energy.
However, no steam was expected to be coming from the building at the end of the tunnel.
Crews were being outfitted with protective gear and filtered air respirators as they prepared to approach the PUREX radioactive waste storage tunnel area where steam had been spotted coming from the tunnel.
They will take radiological surveys and start the generators to power lights and cameras inside the tunnel and air sampling equipment to further assess conditions inside and outside of the tunnel.
The Department of Energy continues to say the take cover order is precautionary and that no emergency has been declared. The Emergency Operations Center has not been activated.
A planned National Park Service tour of historic B Reactor was canceled Friday because of the take cover order.
Energy Northwest had planned a tour for leaders of its member utilities and others attending a public forum in Richland this week.
B Reactor is several miles from the area where workers were ordered to stay inside.
B Reactor near the Columbia River, the world’s first production-scale nuclear reactor, is part of the Manhattan Project National Historical Park.
A team was being assembled to go into the work area of the PUREX storage tunnel to investigate after steam was noticed coming from the tunnel.
The steam was spotted coming from a small building at the end of the 1,700-foot-long tunnel closest to the PUREX plant.
The building houses equipment to move a large door that was opened to allow railcars loaded with radioactive waste to be pushed into the tunnel from the mid 60s until 1996. The tunnel holds 28 railcars.
The steel door is 24 feet high, 22 feet wide and 7 feet thick.
About 3,300 workers are in the 200 East Area where the take cover order is issued on a typical Hanford work day. However, many workers work 10-hour shifts Monday through Thursday, so the number of workers in the area Friday was not immediately known.
Some employees scheduled to work in central Hanford may not have arrived at work before the take cover order was issued.
The take cover order remains in place as a precaution.
A take cover alert was issued at 6:03 a.m. in the 200 East Area.
It included about 350 to 400 workers at the construction site of the $17 billion vitrification plant.
In addition about 180 workers assigned to Hanford environmental cleanup contractors — Washington River Protection Solutions, CH2M Hill Plateau Remediation Co. and Mission Support Alliance — were at work in the 200 East Area and were ordered to take cover.
At 8:30 a.m. the take cover order remained in place as a precaution, according to the Department of Energy.
Steam had been seen coming from a place it was not expected at the PUREX plant tunnel storing obsolete or failed equipment that is highly contaminated with radioactive waste.
Work has been underway to fill the tunnel with concrete-like grout to stabilize it after it was found to be at risk of collapse. The work began at the start of the month but had not begun yet Friday morning.
There is no immediate indication of a release of radioactive material, according to a message to workers.
The issue appeared to be limited to the immediate vicinity of the tunnel. DOE said an emergency had not been declared.
The Department of Energy said the tunnel needed to be filled because there was a risk of particles of radioactive material becoming airborne if the tunnel failed and exposed the waste it held to the atmosphere.
Another PUREX plant tunnel partially collapsed in May 2017.
It prompted a sitewide take cover order that sent thousands of workers indoors for several hours and some tense hours for residents of nearby communities until it was determined that no radioactive particles had become airborne.
That tunnel was filled with grout in November to prevent further collapse.
The collapse of that tunnel, which is 360 feet long and holds eight railcars loaded with radioactive waste, prompted a look at the second tunnel built eight years later.
An initial study completed in the spring of 2017 found it also was at risk of collapse.
Concerns increased in the spring of 2018 when video taken inside the tunnel showed corrosion in the bolts used to anchor steel beams to the concrete arches of the tunnel and corrosion in the beams at one end of the tunnel.
Corrosion increases the risk the tunnel could fail.
Grouting of the tunnel began as soon as the Washington state Department of Ecology, a regulator on the project, completed a public comment period and approved the work.
The PUREX plant was used from 1956 until 1972 and again from 1983 to 1988 to chemically separate plutonium from uranium fuel irradiated at Hanford reactors. The plant processed about 75 percent of the plutonium produced at Hanford for the nation’s nuclear weapons program.
Much of the waste stored in the two tunnels came from the PUREX plant.
Check back for updates.