December 23, 2016

Followup Audit of the Department’s Heavy Water Inventory

The Department of Energy and National Nuclear Security Administration (NNSA) inventory of heavy water is a vital national security asset.  Heavy water, primarily managed and stored at the Y-12 National Security Complex (Y-12), is used in NNSA Weapons Activities to produce parts for weapons system life extension programs and to support National Ignition Facility (NIF) nuclear weapon design and simulation missions.  Additional heavy water inventories are located at the Oak Ridge National Laboratory, used primarily for non-Weapons Activities such as Spallation Neutron Source research and development, and at the Savannah River Site, which maintains an inventory unusable for current programs and planned for future disposal.

In July 2008, our report on Nuclear Weapons Programs Heavy Water Inventory (DOE/IG-0798) identified the need to secure new sources of heavy water because the inventory was likely to be depleted by 2019.  Management agreed with the prior report, and in response, a heavy water assessment was completed in 2009 that defined options to meet heavy water requirements.  In 2010, the Department obtained additional heavy water from the Department of Defense.  Also, NNSA officials told us that they had not been supplying heavy water to non-Weapons Activities, essentially establishing a reserve for NNSA missions, although an NNSA official said they would consider requests from other programs under certain circumstances.  In 2012, Y-12 replaced its traditional production process for lithium deuteride weapons parts, which required heavy water, with the Direct Material Manufacturing process, which recycles these weapons parts and significantly decreased the demand for heavy water. 

In our followup audit on the Department’s management of its inventory of heavy water, we determined that, while the Department had taken several actions to address heavy water requirements to meet mission needs through fiscal year (FY) 2031, management of the heavy water inventory may not ensure a sufficient supply for Weapons Activities beyond that time. 

According to Department officials, actions to address Weapons Activities heavy water requirements after FY 2031 were not taken because, based on Nuclear Materials Management forecasts developed in 2012, when Y-12 fully implemented the Direct Material Manufacturing process, the Department determined that the heavy water inventory was adequate to meet program requirements through FY 2031 and beyond, which would afford sufficient time to prepare plans to meet needs beyond that date.  Thus, the Department did not have any concerns regarding the long-term availability of heavy water.  Therefore, the Department had not established a point, such as an inventory level or other trigger point, when it would begin to pursue other options for acquiring heavy water for Weapons Activities.  However, given the uncertainty of heavy water requirements beyond 2031, the long lead time to establish a production capability, and the estimated lead time to develop recycle or re-enrichment capabilities, the Department may be at risk of being unable to meet all of its Weapons Activities heavy water requirements in the long term.  

Topic: Management & Administration