Saltcake comprises 24  million gallons of the waste in the Hanford tanks and about 20 percent  of the radioactivity. Leak detection. To address these RCRA requirements, DOE conducts a variety of  assessments and monitoring activities. Condition of Tanks Is Worse than Assumed under DOE’s Current Schedule for Retrieving Tank Waste

DOE’s recent assessments of the SSTs and DSTs determined that they  are in worse condition than DOE had assumed when developing its 2011  System Plan schedule for emptying the tanks.series of assessments in 2013 and 2014, DOE concluded that water is  intruding into at least 14 SSTs and that at least 1, T-111, is actively  leaking. For DSTs, DOE concluded in 2012 that waste was leaking from  the primary shell in tank AY-102 and subsequently found that 12 other  DSTs have construction flaws similar to those that contributed to the leak  in AY-102. According to a DOE report on intrusions,  water intrusion creates additional liquid waste in the tanks as the new  water becomes contaminated by the waste in the tanks. According to DOE officials, waste is  leaking at a rate of approximately 640 gallons annually, and DOE  continues to monitor the leak in tank T-111. DOE  reported in October 2012 that tank construction flaws and corrosion in the  bottom of the tank stemming from the type of waste and the sequence in  which it was loaded into the tank AY-102 were the likely causes for the   According to a 2014 expert panel reviewing the leak,  leak in AY-102.corrosion was among the likely causes of the leak. Beginning in 2013, DOE examined  the other 27 DSTs to determine the extent to which they had construction  flaws similar to AY-102. DOE Has Taken and Planned Several Actions to Respond to Recent Leaks and Intrusions, Including Modifying Its Tank Monitoring and Inspection Procedures

Following the discovery of the leaks in tanks T-111 and AY-102, and  water intrusions in some SSTs, DOE has undertaken or planned several  actions. For the SSTs, DOE has, among other things, performed  additional inspections and temporarily increased the frequency of  monitoring the tank waste levels from annually or quarterly to monthly. In addition, in April 2014, DOE formally  modified its inspection procedures by shortening the time between  inspections from every 5 to 7 years to every 3 years. DOE’s Current Waste Retrieval Schedule Does Not Account for the Worsening Condition of the Tanks or WTP Delays

DOE’s current schedule for retrieving the waste from the tanks  (developed in 2011), which includes transferring waste from SSTs to  DSTs and treating the waste in the DSTs, does not take into account the  worsening conditions of the tanks or the delays in the construction of the  WTP. The leak in AY-102 combined with planned waste transfers has  reduced the available DST space, and DOE’s plans to create additional  space remain uncertain. Future leaks and intrusions, which become more  likely as the tanks’ conditions worsen, would place additional demands on  the limited available DST space, and it is unclear how DOE would  respond. According to DOE, recent efforts to evaporate some of the water  from the waste have already freed up 750,000 gallons of DST space. As a result, it is  unclear how long waste will remain in the tanks. However, without an  analysis of the extent to which the factors which may have led to the leak  in AY-102 are present in the other DSTs, DOE cannot be sure how long  its DSTs will be able to safely store the waste. DOE has not estimated the impact of the WTP delay on its tank  management plans, but delays in the schedule to retrieve waste from the  SSTs are already occurring. DOE further reported in March 2014  that delays in the WTP will affect the schedule for retrieving waste from  the tanks but that, until the technology it is developing to treat the tank  waste in the WTP can be demonstrated to work as intended, it is  impossible to estimate what the impact will be on the retrieval of waste  from the tanks. members of DOE’s 2014 expert panel, convened to examine the integrity  of the DSTs, have stated that corrosion is a threat to DST integrity, and  the expert panel also highlighted deficiencies in DOE’s understanding of  corrosion in all of the DSTs. However, as noted previously, DOE has not  examined the other DSTs for the same corrosion factors that may have  lead to corrosion in AY-102 and therefore lacks information about the  extent to which the other 27 DSTs may also be susceptible to similar  corrosion. Recommendations for Executive Action

To ensure that DOE’s long-term plans for storing waste in the existing  SSTs and DSTs at Hanford consider the condition of the tanks and the  WTP construction delay, we recommend that the Secretary of Energy  take the following three actions:
Assess the extent to which the factors that may have led to corrosion  in AY-102 are present in any of the other 27 DSTs. Update the schedule for retrieving waste from the tanks, taking into  the impact of the delays in the WTP,  the risks associated with continuing to store waste in aging tanks,  and an analysis of available DST space. In  its written comments, reproduced in appendix IV, DOE agreed with the  report and its recommendations.
Why GAO Did This Study

DOE recently reported that nuclear waste is leaking from two of its underground storage tanks (T-111 and AY-102) at Hanford and that water was intruding into AY-102 and other tanks. Also, DOE has been experiencing delays in the construction of the WTP, a collection of facilities that are to treat the tank waste for disposal. These recently reported leaks and intrusions, combined with construction delays, have raised questions among regulators, the public, and Congress about the risks posed by continuing to store waste in the aging tanks.
GAO was asked to report on the tank waste cleanup program. This report examines: (1) the condition of the tanks, (2) actions DOE has taken or planned to respond to the recent tank leaks and water intrusions, and (3) the extent to which DOE's tank management plans consider the condition of the tanks and the delays in completing construction of the WTP. GAO obtained and reviewed relevant reports concerning the leaks, the status of the tanks, and the volumes of waste and available space in the tanks. GAO toured the site and interviewed DOE officials and responsible contractors.

What GAO Found

From 2012 to 2014, the Department of Energy (DOE) assessed the physical condition of the 177 storage tanks at its Hanford, Washington, site in which it stores about 56 million gallons of nuclear waste and found them to be in worse condition than it assumed in 2011 when developing its schedule for emptying the tanks. For the 149 single-shell tanks (SST), DOE previously pumped nearly all of the liquid waste out of the SSTs into the 28 newer double-shell tanks (DST) to reduce the likelihood of leaks. However, after detecting water intruding into several SSTs, DOE reexamined them all and found that water was intruding into at least 14 SSTs and that 1 of them (T-111) had been actively leaking into the ground since about 2010 at a rate of about 640 gallons annually. Regarding the DSTs, in 2012, DOE discovered a leak from the primary shell in tank AY-102. DOE determined that the leak was likely caused by construction flaws and corrosion in the bottom of the tank. DOE found that 12 DSTs have similar construction flaws but has not determined the extent to which the other 27 DSTs are subject to the same corrosion that likely contributed to the leak in AY-102.
In response to the waste leaks and water intrusion, DOE has taken or planned several actions. For SSTs, DOE conducted additional tank inspections and temporarily increased the frequency of monitoring the tank waste levels from annually or quarterly to monthly. In addition, after finding flaws in its methods to monitor for leaks and intrusions, DOE modified its methods, which it believes may lead to more effective monitoring. For DSTs, DOE increased the frequency (from every 5 to 7 years to every 3 years) and scope of its tank inspections and convened a panel of experts to evaluate existing tank monitoring and inspection procedures. DOE also plans an independent assessment of the integrity of the DSTs (scheduled to be completed no later than 2016).
DOE's current schedule for managing the tank waste does not consider the worsening conditions of the tanks or the delays in the construction of the Waste Treatment and Immobilization Plant (WTP), a facility being constructed to treat the waste and prepare it for final, long-term disposal. First, the leak in AY-102 combined with planned waste transfers from SSTs has reduced the available DST tank storage capacity. Future leaks and intrusions, which become more likely as the tanks' condition worsens, would place additional demands on the already limited DST storage space, and it is unclear how DOE would respond. According to DOE, recent efforts to evaporate some of the water from the waste have already freed up 750,000 gallons of DST space. Second, in March 2014, DOE announced further delays in the construction of the WTP and that these delays will affect the schedule for removing waste from the tanks. However, DOE has not estimated the impact of the WTP delays on its schedule to remove the waste from the tanks. As a result, DOE cannot estimate how long the waste will remain in the aging tanks. Also, DOE officials and members of a 2014 expert panel convened to examine the integrity of the DSTs have said that corrosion is a threat to DST integrity, and, according to the panel, that there are deficiencies in DOE's understanding of corrosion in all of the DSTs. DOE lacks information about the extent to which the other 27 DSTs may also be susceptible to corrosion similar to AY-102. Without determining the extent to which the factors that contributed to the leak in AY-102 were similar to the other 27 DSTs, DOE cannot be sure how long its DSTs can safely store waste.

What GAO Recommends

GAO recommends that DOE assess the extent to which other DSTs have corrosion factors similar to AY-102, update its schedule for removing waste from the tanks, and assess the alternatives for creating additional DST space. DOE agreed with this report and its recommendations.