Thursday, April 4, 2013

Hanford Nuclear plant and fukushima nuclear plant - one thing in common is concern of hydrogen gas explosions !

http://ex-skf.blogspot.com/2013/04/us-defense-nuclear-facilities-safety.html


TUESDAY, APRIL 2, 2013

US Defense Nuclear Facilities Safety Board: Hanford Nuclear Waste Tanks Could Explode Because of Hydrogen Buildup


Hanford tanks are not only leaking but they could also explode. That would be spectacular, wouldn't it? (Defense in Depth, anyone? NRC commissioners?)

But the Board's comment came during the Senate Energy and Natural Resources Committee hearing, which will hold confirmation hearing next week for the new Energy Secretary nominee. As AP's article indicates, it's part political jockeying among Senators, although the danger is real.

From Huffington Post quoting AP in its entirety, it seems (4/2/2013; emphasis is mine):
Hanford Nuclear Waste Tanks Could Explode, Agency Warns

By SHANNON DININNY

YAKIMA, Wash. -- Underground tanks that hold a stew of toxic, radioactive waste at the nation's most contaminated nuclear site pose a possible risk of explosion, a nuclear safety board said in advance of confirmation hearings for the next leader of the Energy Department.

State and federal officials have long known that hydrogen gas could build up inside the tanks at the Hanford Nuclear Reservation, leading to an explosion that would release radioactive material. The Defense Nuclear Facilities Safety Board recommended additional monitoring and ventilation of the tanks last fall, and federal officials were working to develop a plan to implement the recommendation.

The board expressed those concerns again Monday to U.S. Sen. Ron Wyden, D-Ore., who is chairman of the Senate Energy and Natural Resources Committee and had sought the board's perspective about cleanup at Hanford.

The federal government created Hanford in the 1940s as part of the secret Manhattan Project to build the atomic bomb. It spends billions of dollars to clean up the 586-square-mile site neighboring the Columbia River, the southern border between Washington and Oregon and the Pacific Northwest's largest waterway.

Federal officials have said six underground tanks at the site are leaking into the soil, threatening the groundwater, and technical problems have delayed construction of a plant to treat the waste for long-term safe disposal.

Those issues are likely to come up during confirmation hearings next week for Energy Secretary-nominee Ernest J. Moniz. The fears of explosion and contamination could give Washington and Oregon officials more cloutas they push for cleanup of the World War II-era site.

Central to the cleanup are the removal of 56 million gallons of highly radioactive, toxic waste left from plutonium production from underground tanks. Many of the site's single-shell tanks, which have just one wall, have leaked in the past, and state and federal officials announced in February that six such tanks are leaking anew.

"The next Secretary of Energy - Dr. Moniz - needs to understand that a major part of his job is going to be to get the Hanford cleanup back on track, and I plan to stress that at his confirmation hearing next week," Wyden said in a statement Tuesday.

The nuclear safety board warned about the risk of explosion to Wyden, who wanted comment on the safety and operation of Hanford's tanks, technical issues that have been raised about the design of a plant to treat the waste in those tanks, and Hanford's overall safety culture.

In addition to the leaks, the board noted concerns about the potential for hydrogen gas buildup within a tank, in particular those with a double wall, which contain deadly waste that was previously pumped out of the leaking single-shell tanks.

"All the double-shell tanks contain waste that continuously generates some flammable gas," the board said. "This gas will eventually reach flammable conditions if adequate ventilation is not provided."

It also noted technical challenges with the waste treatment plant, which is being built to encase the waste in glasslike logs for long-term disposal. Those challenges must be resolved before parts of the plant can be completed, the board said.

The federal government spends about $2 billion annually on Hanford cleanup – roughly one-third of its entire budget for nuclear cleanup nationally. About $690 million of that goes toward design and construction of the plant. Design of the plant, last estimated at more than $12.3 billion, is 85 percent complete, while construction is more than 50 percent complete.

The problems identified by the board show that the plant schedule will be delayed further and the cost will keep rising, Wyden said, adding: "There is a real question as to whether the plant, as currently designed, will work at all."

Dr. Ernest J. Moniz, President Obama's Energy Secretary nominee, is a nuclear physicist at MIT. He is a founding member of The Cyprus Institute, based in Nicosia, Cyprus, a private, "non-profit research and education institution with a scientific and technological orientation" according to Wikipedia.

Whatever this institution is, I wonder if they managed to move their money out of Cyprus in a timely manner.


http://fukushima-diary.com/2013/04/tepco-to-restart-nitrogen-injection-to-reactor1-the-volume-of-gas-is-40-more-than-last-time/

Tepco to restart nitrogen injection to reactor1, “The volume of gas is 40% more than last time”

According to Tepco, they are going to restart nitrogen injection into the suppression chamber of reactor1.
6~7m3/h will be injected in order to “push out the retained hydrogen gas” and also “look into the effect of radiolysis of water within suppression chamber”, which implies Tepco admits hydrogen gas is being produced from the radiolysis of water.
They injected nitrogen gas into reactor1 on 2/26/2013 as well, but it was 5m3/h, which was only 71 ~ 83% of this time.
If the hydrogen gas density goes over 2%, there is a possibility of further hydrogen explosion.

Tepco to restart nitrogen injection to reactor1, "The volume of gas is 40% more than last time"





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