Updated December 4, 2025
Work is Underway to Move the WESF Capsules to Dry Storage!
The Waste Encapsulation Storage Facility (WESF “wessif”) stores 1,936 highly radioactive cesium and strontium capsules under 13 feet of water in degrading concrete storage pools. You may recall that this facility, with its degrading concrete storage pools, is a serious risk—which we shared in this 2020 animated video. A major risk is water draining from the pools that store the radioactive capsules. Once exposed, the extreme radioactivity of the capsules makes safe human entry impossible and could result in a widespread release of contamination.
The great news is that work to move the extremely radioactive cesium and strontium capsules out of the WESF’s underwater pools and into dry storage started in November 2025!
We applaud the Hanford workforce and regulators for all the hard work to get to safe startup of this high-risk cleanup project!
What is the cleanup plan?
Hanford contractor, Central Plateau Cleanup Company (CPCCo “see-pee-see-coe”), is responsible for the work at WESF. Workers have been training for this work on a full-scale mock up.
The WESF capsules contain one-third of the total radioactivity of waste on the Hanford site! This is equivalent to about 80 million curies. For reference, the radioactivity released during the Chernobyl disaster is estimated at 50-200 million curies. In other words, it would be a REALLY BAD DAY if the 80 million curies of radioactivity in the WESF storage pools was released. So it is VERY good news that the work is underway to move these capsules to the safer configuration of dry storage.
How long will it take to move the capsules to dry storage?
The work to move all of the capsules to dry storage should be completed by 2028 or 2029.
The original milestone to complete the capsule transfer was 2025, however, Ecology was first notified in November 2021 that the August 2025 milestone was at risk of being missed due to the COVID-19 pandemic and supply chain issues. On April 25, 2025, the agencies notified the public that they had revised the Tri-Party Agreement milestone for completing this transfer from Aug. 31, 2025 to Sept. 30, 2029. The changed milestone gives USDOE and its contractor four years to complete the capsule transfers.
There are a total of 18 dry storage casks and the contractor and USDOE estimate it will take 1.5-2 months to load each cask to capacity with capsules from the storage pools. If everything goes according to plan, it will take about 3 years to transfer the capsules from start to finish. The capsule transfer operations started in November 2025, but workers have been training for this complicated and dangerous job for years.
USDOE’s goal is to finish transfers by the end of calendar year 2028, but they have until 2029 (through the agreement with the State of Washington) to account for any unexpected downtime during the transfers. Hanford Challenge has been incredibly concerned about how delays could increase the risks this facility poses to human and environmental health. We are very glad this work is has started and continue to monitor reports from the Defense Nuclear Facilities Safety Board for potential issues with the project.
How do the capsules get moved from the pools to dry storage?
WESF’s high-level waste is moved to dry storage using remotely operated equipment. The steps look something like this (adapted from the voice over in this CPCCo video).
Workers on a catwalk use long-reach poles to access the capsules that are stored under 13 feet of water. The water protects workers from the radiation.
Capsules are moved into G cell, a hot cell in WESF, through a transfer chute.
Workers inspect the capsules through a shielded window, looking for damage and ensuring compliance with capsule storage thermal analysis.
If damaged, the capsule is placed in a larger overpack capsule.
Workers use manipulator arms and a special insertion tool to place the capsule into a Universal Capsule Sleeve (UCS). Each UCS can hold up to 6 capsules.
This process repeats until the Universal Capsule Sleeve is full. When needed, a spacer will be added instead of a capsule to balance out heat loading within the Universal Capsule Sleeve.
Once full, the air inside the Universal Capsule Sleeve is displaced with helium to help dissipate the heat from the capsules.
Following a successful leak test, the UCS is ready for transfer to the truck port.
Using cameras, workers guide a grapple over the Universal Capsule Sleeve to hoist it out of G cell and into the shielded Dry Transfer System (DTS).
The Dry Transfer System is a large shielded cask that will transfer the Universal Capsule Sleeve (that is holding 6 capsules that have been retrieved from the pools) from G cell into the WESF canyon to the truck port using a 15 ton crane.
The truck port contains an 11-foot tall, 10-foot diameter Vertical Concrete Cask (VCC, cask) shielded with reinforced concrete. The VCC contains storage containers capable of holding up to 22 Universal Capsule Sleeves. If everything is filled to capacity, the cask is capable of holding up to 132 cesium and strontium capsules. When full this cask weighs 185,000 pounds! They are designed to last 300 years.
Once the cask is full, a robotic welder is used to seal the lid of the inner storage container.
The air will be removed and the container will be filled with helium to help keep the capsules cool.
Once the helium is in place, a second outer lid is placed on the storage container and welded in place.
When the loading process is complete, workers open the truck port roll-up door and remove the cask using a remotely operated Air Pallet (like a hoverboard, it is so cool!) that slides the 185,000 pound heavy cask to the vehicle that transfers the cask to the storage area.
The equipment used to move the cask to the storage pad is called a Vertical Cask Transporter (VCT). It is a specially designed hydraulic lift unit that was designed using repurposed equipment (instead of spending money to build something new) from a previous DOE project (which saved millions of dollars).
The tug (vehicle) will tow the Vertical Cask Transporter and the cask it is holding to the capsule storage area, which is a 90x90 foot secure outdoor storage pad about a quarter mile from WESF.
The cask is placed on the pad in one of 25 locations on the pad (extra space was planned in for use if needed), and connected to a temperature monitoring system.
The cask sits on the pad allowing the radiation to decay until a permanent repository is available to store this high-level waste.
Once the final capsules have been retrieved, loaded into Universal Capsule Sleeves, loaded into the cask that can store up to 22 Universal Capsule Sleeves, and placed on the storage pad, WESF can be prepared for demolition.
It is expected to take about 1.5-2 months to load one storage cask, and about 3-4 years to complete the transfer of all of the capsules into dry storage.
Cesium capsules will be loaded together which would take up about 12 total casks. Strontium capsules will be loaded together which is expected to fill around 6 total casks.
You can see these steps play out in this 3 min animated video from CPCCo. Start at the 1:23 timestamp.
We applaud the Hanford workforce and regulators for all the hard work to get to safe startup of this high-risk cleanup project!
Want to learn more? Dive deeper!
Learn more about the Waste Encapsulation Storage Facility below.
CPCCo Video about WESF Capsule Transfer (Start at the 1:23 timestamp to see the transfer steps)
Nov 17, 2025 Tri-City Herald Article: Dangerous nuclear waste in aging WA pool at risk of quakes. What’s being done
Read Hanford Challenge’s 2022 comments on Permit Modification for increasing storage capacity of WESF G Cell, here.
See our 2020 Say What? Guide, here.
See our 2020 sample comments, here.
Read Hanford Challenge’s 2020 comments on Permit Mod to add WESF to RCRA Permit, Section III as Operating Unit Group 14, here.
Columbia Riverkeeper & Hanford Challenge 2020 webinar “Why Scientists Fear a Chernobyl-Like Catastrophe at Hanford,” here.
Dunning, Dirk - WESF Presentation, click here.
Funded in part from a Public Participation Grant from the Washington State Department of Ecology.