Hanford’s owner, The U.S. Department of Energy, is scrambling to deal with the second emergency at the nuclear site in 10 days’ time.

Signs have emerged that a massive underground double shell nuclear waste holding tank may be leaking.

The tank is known as AZ 101 and was put into service in 1976. The tank’s life was expected to be 20 years. Now it has been holding hot, boiling radioactive and chemically contaminated waste for 41 years.

A seven-person crew was undertaking a routine job around 7 p.m. Thursday night. They had deployed a remote controlled devise into the safety space of what is known as a double shell tank. The device is used to evaluate structural integrity of the aging tanks. Normally, equipment lowered in this two-foot wide outer shell of the tank comes up clean. But not this time. A radiation specialist on the crew detected higher than expected readings.

“Radiological monitoring showed contamination on the unit that was three times the planned limit. Workers immediately stopped working and exited the area according to procedure,” said Rob Roxburgh, deputy manager of WRPS Communications & Public Relations, the government contractor in charge of all 177 underground storage tanks at the nuclear site.

Detection equipment was then used to check for contamination that might have become airborne and adhered to the workers. They found radioactive material on one worker in three spots: on one shoe, on his shirt, and on his pants in the knee area. According to workers in the field, the contaminated items were removed, bagged and appropriately disposed of.

“Everybody was freaked, shocked, surprised,” said a veteran worker, who is in direct contact with crew members. “(The contamination) was not expected. They’re not supposed to find contamination in the annulus (safety perimeter) of the double shell tanks.”

Of Hanford’s 177 underground tanks, 28 of them are double-shells. They were built to withstand the test of time – a more robust model that was supposed to hold the worst nuclear waste on the reservation until a permanent solution for disposal is developed. But Thursday night’s incident means this could be the second double shell tank to fail.

Here is photo of ultrasonic testing crawler used to check safety space of Hanford double shell tanks. Crawler like this came up contaminated.

"We are of course concerned it might be a leak," a Washington state Department of Ecology spokesperson said.

In 2013 the KING 5 Investigators exposed how the federal government and its contractor misled the public and lawmakers about the first double shell tank to leak – AY 102. The series, “Hanford’s Dirty Secrets,” showed how Hanford managers ignored major red flags that AY 102 was leaking, and instead insisted “rainwater” had seeped into the safety space. AY 102 is located about 100 feet from AZ 101.

The AZ 101 contamination event comes just 10 days after a tunnel collapse at Hanford that caused a site wide emergency. On May 9, workers found a 20 by 20 foot cave in of a tunnel used to store highly radioactive and chemically contaminated equipment from the Cold War-era. That event could have spewed radioactive particles across the site and beyond, but due to stagnant air at the time, monitoring has shown no contamination blew out of the huge hole, according to Hanford officials.

Related: Hanford officials ignored own expert's advice on tunnel safety for decades

Governor Jay Inslee called on the federal government to investigate after the contamination was discovered.

"Today's alarming incident at Hanford elevates the urgency of the federal government to prioritize and fund all critical cleanup at this aging nuclear reservation," Inslee said in a statement. "We are not aware of any nuclear waste leaking outside the AZ-101 double-shelled tank, but we expect the U.S. Department of Energy to immediately investigate and report on the source of contamination. 

"This comes on the heels of last week's tunnel collapse. It is another urgent reminder that Congress needs to act, and they need to act quickly." 

Attorney General Bob Ferguson sent out a statement on the potential leak as well.

“Today’s news of another potential leak in a tank at Hanford only strengthens my resolve to hold the Department of Energy accountable for its responsibility to clean up this contaminated site,” Ferguson said. “This isn’t the first potential leak, and it won’t be the last. The risks at Hanford to workers and the environment are all too real, and today’s news is just another illustration of how tenuous the situation is.”