The Department of Energy said it took a conservative approach Friday morning when steam was spotted coming from a building attached to a Hanford tunnel storing radioactive waste.
It did not declare an emergency, but did order more than 500 workers to take cover indoors for four hours until it could confirm that no radioactive contamination had spread.
“When something unexpected or unusual happens, we follow our procedures for acting quickly to protect people until we can determine whether or not a danger exists,” DOE said in a statement issued in response to Herald questions.
“In this case, we think we made the right call to have employees take shelter until we confirmed there was not a hazard,” DOE said.
Work has been underway since the start of the month to fill the second of two PUREX processing plant tunnels with thin layers of concrete-like grout to stabilize it after the tunnel was determined to be at risk of collapse.
DOE anticipated that heat and moisture would be generated in the tunnel as the grout was curing. An exhaust system was installed to remove moisture and filter the air using high efficiency particulate air (HEPA) filters during grouting.
Instead, some of the vapor escaped through the seal of a large door used to open and shut the tunnel when rail cars loaded with radioactively contaminated equipment were pushed inside for storage.
The incident follows more serious events on the 580-square-mile site dating back to May 2017.
That’s when the roof of a different, nearby Hanford waste storage tunnel partially collapsed, as DOE was focused on what appeared to be more pressing issues at the Hanford nuclear reservation after past production of plutonium for the nation’s nuclear weapons program.
High priority projects include emptying leak-prone underground tanks holding radioactive waste, removing a highly radioactive spill beneath a building just north of Richland and demolition of one of the most contaminated buildings in the DOE complex, the Plutonium Finishing Plant.
When the tunnel partially caved in in 2017, an emergency was declared and the Hanford Emergency Operations Center was activated.
Several thousand workers were ordered to take shelter, most of them for several hours. Many in the Tri-Cities waited anxiously to learn if loved ones at Hanford were OK and whether the local communities were at risk.
About six hours after the emergency was declared, operations moved from an emergency phase to a recovery phase. No airborne release of radioactive material had been detected.
A take cover order is considered precautionary, as it was in Friday’s steam release, when it is not known whether the event is exposing people to hazards, according to DOE.
When more is known, the event could develop into what DOE considers an emergency under the Hanford Emergency Management Plan, DOE said.
Public concerns about Hanford were raised not only by the 2017 partial tunnel collapse, but also by problems that year controlling the spread of radioactive particles during the high-hazard demolition of the Plutonium Finishing Plant.
In two incidents, 42 workers inhaled or ingested small amounts of radioactive particles. Several workers drove their cars home, not realizing that the cars were contaminated with specks of radioactive material.
The Washington state Department of Health reported finding very small amounts of radioactive material in air samples collected miles from the plant near the Columbia River and public Highway 240.
In the first of the Plutonium Finishing Plant incidents in July, workers were ordered to take cover indoors when an air monitoring alarm sounded. In the second incident in December, no air monitoring alarm sounded and the spread of contamination initially went undetected.
“We hope public confidence in a situation like Friday’s would be increased by the fact that we act conservatively to protect people until we know whether or not there is a danger,” DOE said on Monday.
DOE’s Hanford permit from the Washington state Department of Ecology requires that in certain emergencies DOE activate a contingency plan and keep Ecology informed as events unfold.
DOE believed there had been no release of contaminants, but as a conservative measure activated its contingency plan until it knew more, said Randy Bradbury, spokesman for the Department of Ecology.
“Energy did notify us almost immediately Friday after the stop-work was ordered, and did a good job of keeping us informed through the morning as investigators confirmed that there had been no release of contamination,” Bradbury said.
DOE is required by its state permit to submit a report within 15 days that outlines what occurred and assesses whether there will be any effect on the ongoing work, he said.
DOE said that the shield door housing was patched over the weekend.
Grouting of the tunnel will not resume until workers take another look at other portions of the tunnel — including its original, deactivated ventilation system — to make sure there will be no additional issues with steam escaping.
A crew sent into the area of the tunnel to investigate Friday morning turned on generators to power lights and cameras already in the tunnel, and the cameras confirmed the tunnel was filled with steam. They also surveyed for any release of radioactive contaminants, finding none.
The Washington state Department of Health also has air monitoring equipment set up near the tunnel for the duration of the grouting project and had one near the building where the steam escaped, said John Martell, manager of the Radioactive Air Emissions Section of the department’s Office of Radiation Protection.
The air sample in the monitor will be collected this week, as was previously scheduled, and then will be analyzed. The Department of Health should have data within a couple of weeks on whether its monitor detected any airborne contamination.
The Department of Health also is getting DOE’s data and will be following up with questions for DOE, Martell said.
DOE contacted the Department of Health early Friday morning and was in contact with officials throughout the day, he said.