An old layout of the once top-secret 231-Z Building shows the location of a vault in the lower left corner. The 231-Z Vault was the last stop for weapons-grade plutonium during the first decade of Hanford operations before the “product” — as it was codenamed — was shipped offsite.

An old layout of the once top-secret 231-Z Building shows the location of a vault in the lower left corner. The 231-Z Vault was the last stop for weapons-grade plutonium during the first decade of Hanford operations before the “product” — as it was codenamed — was shipped offsite.

RICHLAND, Wash. – Like the gold at Fort Knox and the Hope Diamond, Hanford’s “valuables” were once housed in one of the most secure facilities in the nation. A top-secret room within a top-secret facility at the sprawling top-secret Hanford Site, a vault in the 231-Z Building protected the site’s plutonium during the first decade of national defense operations.

The plutonium was refined in the building’s laboratory, carefully packed in shipping boxes about twice the size of a shoe box, and locked in the vault.

“The vault was the last stop for the ‘product’ — as the plutonium was codenamed — before it was shipped offsite for weapons production. It was heavily fortified and guarded, and very few people had access or even knowledge of it,” said Rick Raymond, an engineering manager with EM Richland Operations Office contractor Central Plateau Cleanup Company (CPCCo). “The vault certainly played a key role in Hanford’s early history.”

Workers with EM contractor Central Plateau Cleanup Company recently partnered with locksmiths from contractor Hanford Mission Integration Solutions to safely open the historic 231-Z Vault for the first time in 20 years.
Workers with EM contractor Central Plateau Cleanup Company recently partnered with locksmiths from contractor Hanford Mission Integration Solutions to safely open the historic 231-Z Vault for the first time in 20 years.

Today the 231-Z Building containing the vault — its mission long ago accomplished — is set for demolition as part of the site’s ongoing environmental cleanup effort. But before that, crews are preparing the building for safe demolition by opening the vault and characterizing and removing any potential hazards inside.

“We believed the vault to be empty, but we needed to be sure before proceeding with cleanup activities,” said Raymond. “Our team prepared for every scenario to manage the project safely and securely.”

Confirming the 231-Z Building Vault is empty allows crews to continue preparations for demolition of 231-Z.
Confirming the 231-Z Building Vault is empty allows crews to continue preparations for demolition of 231-Z.

To access the vault, which hadn’t been opened in 20 years, locksmiths from site services provider Hanford Mission Integration Solutions worked with CPCCo to drill through the heavy metal door. Workers then used a pry bar to unlock the door manually to allow crews in personal protective equipment and respiratory protection to safely enter.

The foray into 231-Z was ultimately anticlimactic, but confirming the vault is vacant paves the way for progress on a key risk-reduction project on Hanford’s Central Plateau. Demolition preparations will continue over the next few years, and the contractor expects to fully complete demolition work of the building in 2025.