It will take somewhere between nine months and a year longer than hoped to get 27 new sensors for the Hanford Site’s double-shell waste storage tanks in working order, the Energy Department disclosed last week.
DOE was supposed to have the sensors inside the annulus of Hanford’s 28 double-shell tanks working by December 2016, per a recommendation from the Defense Nuclear Facilities Safety Board (DNFSB). However, the agency’s decision to focus on draining waste from one leaky double-shell tank, AY-102, “has delayed progress” on the sensors, Monica Regalbuto, DOE assistant secretary for environmental management, wrote in a Dec. 27 letter to DNFSB Chairman Joyce Connery.
The sensors are intended to detect dangerous levels of flammable gas in each double-shell tank’s annulus — the space between a tank’s inner and outer hulls. When DNFSB in 2012 recommended DOE install the sensors, the agency thought those systems would be up and running in December 2016. Now, the work will not be finished until “the fourth quarter of calendar year 2017,” Regalbuto wrote. Hanford tank farm contractor Washington River Protection Solutions (WRPS) has installed sensors on the 27 tanks besides the leaky AY-102, but the company is still testing the new hardware, Regalbuto wrote.
After worker reports on the tank farm, WRPS acknowledged AY-102 was leaking in 2012. The tank, which was supposed to feed liquid waste into the Waste Treatment Plant under construction at Hanford, will not be fitted with a flammable gas sensor; once the tank is empty, there will be no possibility of flammable gas buildup, DOE said.
Meanwhile, Hanford’s double-shell tanks already are outfitted with other sensors, Regalbuto wrote. The existing devices “meet environmental requirements” and also allow WRPS to monitor tank ventilation so that “sufficient ventilation will continue to be provided,” she stated.
