Work at one of Hanford's tank farms was halted Wednesday night after radiation was detected during the transfer of nuclear sludge.
The alarm was issued shortly after 9:35 p.m. at the C Farm, a collection of single-shell waste tanks in the 200 East area at Hanford. Workers evacuated the C Farm and others working in nearby areas were ordered to shelter in place.
The alert ended Thursday morning and the Department of Ecology believes the incident was contained.
A project has been underway in this area to move waste from aging tanks to double-shell tanks where it will be held until a final waste treatment solution is in place.
The take cover ordered was lifted after an additional survey of the tank farm area found no detectable radiation. Workers returned to work as normal but officials planned to investigate the incident further.
Follow-up statement from the Department of Ecology:
Washington Department of Ecology statement on Hanford tank farm alert
The Department of Ecology has been closely following an incident at Hanford s C Tank Farm since an alert was issued at 9:35 p.m. Wednesday, August 21, 2013, due to the results of routine radiological monitoring that indicated a potential leak of tank waste. The higher readings were found around a box that is part of a waste transfer system for Tank C-101. The tank farms are located in the central part of the Hanford Site.
The alert ended early this morning, and Ecology believes the incident is contained. There were no reports of injuries to workers, and the Department of Health confirmed that there is no threat to public health or the environment. We are pleased with the response from both the U.S. Department of Energy (USDOE) and the contractor, Washington River Protection Solutions, to address the incident quickly and provide prompt notification to the State.
Ecology is still working to learn precisely what caused the higher than normal reading, and will continue to follow up with USDOE to gather more information about this incident.
Tank C-101 is one of 7 tanks remaining to be retrieved of the 16 tanks in C Farm. Under a legally enforceable Consent Decree, USDOE is required to finish retrieving waste from all C Farm tanks by September 2014. Due to this incident, the transfer of waste from C-101 to a double-shell tank has been halted until crews are able to investigate further and ensure that it is safe to resume work. It is unknown how long this will take or how any delays may affect USDOE s ability to meet the 2014 waste retrieval deadline.
USDOE had already notified Ecology in June that they may not be able to retrieve waste from tanks C-102 and C-105 in time to meet the 2014 deadline. We still expect the federal government to provide the State with additional information including details for the reasons for the delays, the nature of the review being undertaken by USDOE and its contractors, the environmental risks of the delay, and the recovery schedule for completion of these milestones.
Original statement from the Department of Energy:
HANFORD EMERGENCY INFORMATION
An ALERT level emergency was declared at 9:35 PM (PST) at the Hanford Site due to radiological survey results that indicated a potential leak of tank waste from a transfer system in the C Tank Farm, which is in Hanford s 200 East Area.
Approximately 80% of the waste from single-shell tank (SST) C-101 has been retrieved and transferred to double-shell tank (DST) AN-101, leaving just a few inches of difficult-to-retrieve hard heel waste. Retrieval crews were using the Enhanced Reach Sluicing System (ERSS) high pressure nozzles (clean water at nearly 5,000 psi) to mobilize remaining waste. A Health Physics Technician (HPT), performing a routine radiological survey at 9:20 PM, found that at the base of the C-101 Sluicer #1 shield box, dose rate readings were 150 mr/hr open window, and only 6 mr/hr closed window. This disparity in the reading indicates beta-emitting material may have leaked outside either the hose-in-hose transfer line (HIHTL) or the containment box for Sluicer #1. The Health Physics Technician also performed a swipe measurement at the location of the elevated dose rate, and the swipe indicated a radioactive contamination reading of 180,000 disintegrations per minute (dpm). There were no visible indications of a release of any tank waste material.
Field personnel immediately stopped use of C-101 retrieval systems, and evacuated the tank farm. No contamination was found on any of the workers that were inside the C Tank Farm. The four workers that were evacuated were sent to Kadlec Hospital in Richland, WA for additional monitoring as a precaution. None of the C Farm remote area radiation monitors nor the industrial hygiene monitoring equipment indicated any abnormal conditions.
Per the Emergency Action Level Criteria, an ALERT level (the lowest level) emergency is declared when there are liquid waste leaks from a waste transfer system resulting in waste on the ground as evidenced by observation or indication of abnormal increased beta dose rates.
An ALERT level emergency was declared at 9:35 PM, and the Hanford Emergency Operations Center (EOC) was activated at approximately 9:50 PM (fully staffed by 10:35 PM). The Hanford 200 East, 200 West, 600 and 100-K areas were placed in a take cover condition. The take cover area was reduced by 12:35 AM to just the 200 East area and the Waste Treatment Plant (WTP) as monitoring outside the 200 East area showed no abnormal conditions.
By 1:18 AM, a perimeter survey of the C Tank Farm was completed, with no abnormal radiation readings above background, and no presence of hazardous chemicals. Airborne monitoring downwind of the C Tank Farm has been established, and HPTs and Industrial Hygiene Technicians (IHT) prepared to enter C Tank Farm using Self-Contained Breathing Apparatus (SCBA) equipment to take additional readings and attempt to locate the location of any potential release. Emergency personnel developed plans to establish 9 barricades around the C Tank Farm with the intent of lifting the take cover condition in the 200 East Area and adjacent areas by 4:00 AM.
At 3:52 AM, five personnel entered the C Tank Farm to perform additional monitoring in the vicinity of the Tank C-101 Sluicer #1 shield box. The team consisted of two firemen, one nuclear chemical operator, one industrial hygiene technician, and one health physics technician. There was no visible indication of any leakage. No additional radiation fields or contamination were found beyond the original location low on the shield box. Readings were less than originally discovered. The on-contact open window dose rate reading was down from 150 mrad/hr to 100 mrad/hr. The closed window dose rate reading remained the same at 6 mrem/hr. When the instrument was backed off to one foot away from the shield box wall, the readings dropped off to background levels. The removable contamination was down from the original 180,000 dpm to 10,000 dpm. Fixative was applied to the location of the contamination, covering a three square foot area, to prevent spread of contamination.
At 4:03 a.m., the take cover protective action was lifted from the 200 East Area and adjacent areas, after installation of barricades around the C Tank Farm. Hanford workers were notified to report to work as normal.
The Emergency Operations Center terminated the Alert-level emergency at 5:05 a.m. Contractor Retrieval Operations personnel will perform follow-up evaluation in the C Tank Farm. While higher than expected levels of radiation were confirmed, there is no visual indication of a leak or spill in C Farm.
The four employees sent to Kadlec Hospital have no indications of any dose from the surveys completed on-site prior to going to the hospital. Each of the employees had blood and urine samples taken and we will have results in about one week. All of the employees were released to return to work with no restrictions.
Conditions in the C Tank Farm are stable and workers are transitioning back to normal operations. Barricades will remain around C Farm until workers have fully transitioned to normal operations.