By Bob Young
The Seattle Times
SEATTLE — Crews have begun filling in a 400-square-foot collapse in a tunnel that is loaded with radioactive waste at the Hanford nuclear reservation near Richland, Wash., the Department of Energy said Wednesday.
The discovery of the hole Tuesday forced thousands of workers to shelter indoors for hours, although there were no injuries reported and the department said there was no indication of a radioactive release.
Crews worked overnight, laying a gravel bed to make a road for heavy equipment to reach the site of the tunnel cave-in, Destry Henderson, a Hanford spokesman, said Wednesday.
“No action is required for residents of Benton and Franklin counties,” the department said.
On Wednesday morning, crews began filling the cave-in with soil. The department estimated that about 50 truckloads of soil would be needed to “stabilize that portion of the tunnel.”
A misting machine is being used to control dust.
Workers in the area are wearing protective suits and breathing masks, the department said, and there is air monitoring in the area.
“We’re going to approach this slowly, safely and methodically,” Henderson said.
Nearly 4,800 workers at the nuclear site were told to take shelter indoors Tuesday after the tunnel collapse. Workers were allowed to go home about five hours later.
On Wednesday, nonessential employees were told to stay home, Henderson said.
The tunnel is the smaller of two located next to the Plutonium Uranium Extraction Facility, known as PUREX, in the center of Hanford at the 200 East Area.
Known as tunnel No. 1, it is 360 feet long and contains eight rail cars filled with radioactive material. Sealed in 1965, the tunnel contains 780 cubic yards of waste. The hole opened up near where the tunnel joins the larger tunnel No. 2, which holds 28 rail cars filled with 2,883 cubic yards of waste, and is large enough to accept more waste.
The tunnels are made of wood and concrete and are covered by 8 about feet of soil.
“The issue is whether or not there’s sufficient wind to start sucking materials out of that tunnel and into the environment,” said Tom Carpenter, executive director of Hanford Challenge, a Hanford watchdog organization.
Carpenter said that radioactive gamma rays are “certainly” coming out of the tunnel, but those diffuse quickly with distance and are not carried by wind. If radioactive dust or soil were to be released from the site it would be a different story.
Radiation levels within the tunnels were lethal within an hour, according to Heart of America NW, another Hanford watchdog group.
Hanford made plutonium for nuclear weapons beginning in 1943 and continuing for more than 40 years, including for the bomb dropped over Nagasaki, Japan. Now, about 8,000 people are working on a massive cleanup that is expected to cost more than $100 billion and last through 2060.
About six Hanford employees discovered the tunnel collapse Tuesday morning and an emergency was declared about 8:30 a.m. But it is unclear when the collapse actually occurred.
The Department of Energy said the exterior of the tunnels are inspected “periodically.” (The interior of the tunnels is extremely hazardous and is not inspected.)
An inspection plan for the tunnels, from the Washington Department of Ecology, which monitors cleanup work at the site, says that external tunnel inspections are done annually.
“I know that’s one of the things that they’ve been trying to determine, is when it might have happened,” said Ken Niles, the administrator of the Oregon Hanford Cleanup Board for the Oregon Department of Ecology. “As far as we’ve been told, they’re not certain when it might have opened.”
There have been prior warnings about the tunnels.
A 2015 academic report, done for the Department of Energy, warned that a seismic event could lead to the “total structural failure” of both tunnels.
It also warned that “the wood ceiling and wall structure of tunnel No. 1 are vulnerable to collapse in about 30 years due to ongoing degradation occurring from continued exposure to the gamma radiation from equipment being stored.”
And in 2016, the Hanford Advisory Board advised cleanup authorities to “expeditiously investigate” the risks posed by the tunnels.
Still, the heavy equipment stored in the tunnels, while highly radioactive, is less dangerous than many other sites at Hanford which contain radioactive liquids and sludges that are much more likely to disperse if their containers are breached.
The site has 55 million gallons of highly radioactive waste stored in 177 underground tanks, as well as thousands of tons of used nuclear fuel and huge amounts of contaminated buildings, soil and groundwater.
“You look at the list of cleanup priorities and it numbers in the hundreds of items. The PUREX tunnels are way down the list, until yesterday. It’s going to move up,” Niles said. “There’s a huge need to put a lot of these facilities and storage facilities into better condition.”
In January, Washington’s entire 12-member congressional delegation wrote to then-President-elect Donald Trump asking him to make the Hanford cleanup — which currently costs about $2 billion a year — a priority.
