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A wake-up call: Threat “Z” at Hanford

Shortly before Doug Shoop retired from managing Hanford cleanup operations for the US Department of Energy in 2019, he met with members of the Hanford Advisory Board and answered a simple question: of all the issues that need more attention than they are getting now, what keeps him up at night?

And the answer

At the top of his list were the Z-Cribs, old open-bottomed vaults that contain in their soils an estimated 7 kilograms of plutonium. Even more concerning is the 216Z9 Trench. This is a V-shaped 20- foot deep pit thirty feet long and 60 feet wide at its bottom, and 120 feet wide at the top. Up to 48 kilograms of plutonium lie beneath its concrete and brick-lined cover, which is held up by six concrete columns.

A legacy from Cold War days

These waste structures are left over from the old days, from the 1940s to the 1970s, when liquid waste from nuclear weapons fuel production at Hanford was simply discharged to the ground. This was the practice that led to contamination of groundwater flowing into the Columbia River. The “Z” designation comes from Cold War days and refers to structures related to the Plutonium Finishing Plant (PFP), a huge building complex on the Hanford plateau where the fuel “buttons” and plutonium-oxide powder for nuclear weapons were processed.

Plutonium-laden waste remains

The Z-cribs are open-bottomed vaults where over 10 million gallons of liquid waste was dumped into the ground. The Trench received over a million gallons of plutonium-laden waste. Although about 58 kilograms of plutonium were mined from the Trench in the 1960s, up to 48 kilograms remain. In addition, a settling tank used from the 1940s through the 1970s still holds anywhere from 26 to 75 kilograms of plutonium (mainly Pu-239). The heavily contaminated pipes that carried the waste are also degrading underground.

These old waste areas have languished in the face of even more urgent priorities, such as dealing with over 50 million gallons of waste sitting in aging steel tanks — and dismantling the Plutonium Finishing Plant (PFP) itself.

Danger at every turn

The Hanford project to level the Plutonium Finishing Plant (PFP) to the ground has been fraught with danger. An investigation by the Seattle Times, published on March 22, described how CH2M Hill endangered hundreds of cleanup workers in 2016 by supplying respirator equipment with mismatched cartridges.

Poor management of rubble from the building led to a contamination incident where plutonium spread for miles, and over 40 workers were exposed. Inhaled plutonium lodges in the lung and stays there.

On-going accidents

Another recent accident at Hanford, the collapse of an old Purex Plant train tunnel full of highly radioactive equipment “temporarily” stored on rail cars inside, exposed the risks posed by failing old infrastructure at Hanford. If the collapse had occurred in a slightly different place, the falling dirt could have hit some of that equipment and surrounding dirt, causing a release into the atmosphere. It is possible that there was some unrecorded contamination. The collapse was discovered well after it had occurred.

Reasons to stay awake

These incidents point to the great danger posed by the Z-Cribs and Trench. If a major earthquake causes a roof collapse, a truly catastrophic cloud of plutonium could be released into the atmosphere. That should keep everybody in Washington up at night. Plutonium is especially mobile, and contaminated soil released to the air could carry it far and wide.

With continued deterioration, there are other contamination dangers as well, from wildfires to the inadvertent spread of contaminants by animals, or by humans long after the existence of the United States Department of Energy has become a distant memory.

Just cover it up and forget it?

Considering the high risks, costs, and difficulties of cleanup, it is not surprising that the immediate response of the US Department of Energy to this threat of failing “Z” structures at the PFP, now that it has awakened to the immediacy of the problem, is to want to cover the contaminated soil in cement-like grout. With the blessing of the State of Washington, it grouted the PUREX tunnels when it became clear that the second, larger tunnel could fail completely.

Temporary grouting is a logical plan, but Hanford Cleanup watchers understand very well that the greatest risk to our region is allowing the Department of Energy to entomb the waste and eventually forget about it, turning Hanford into a de facto permanent shallow disposal site. From the beginning of Hanford Cleanup in the 1980s, the demand has been to remove, treat, and dispose of Transuranic waste in a way that protects future generations.

Helen Wheatley is a board member of Heart of America Northwest, a regional citizen advocacy group. She represents HOANW on the Hanford Advisory Board.

Participate in a call to clean up not cover up

From now through May 22, the US Department of Energy is taking public comment on its proposal to immediately grout the Z-Cribs and an associated settling tank after removing radioactive sludge from it. They need to hear that grouting is not enough.

On April 9, Heart of America Northwest is sponsoring an Olympia-area webinar to discuss this and other Hanford Cleanup issues, and we’d love to have WIP readers join the conversation. To learn more, go to

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