Nuclear risks at ORNL

[BK911]

Some of you were wondering about nuclear risks in the US. Hot off the press:


HFIR:

ORNL staff members, particularly those involved with nuclear reactor technology, have been watching events in Japan closely. Some of the inquiries coming from media relate to the similarities or differences in power plant reactors and ORNL's research faciliity, the High Flux Isotope Reactor.

It's mainly a matter of size and scale. If a power plant reactor could be compared to an airliner, HFIR would be a small private plane.

Nonreactor Nuclear Facilities Division Director Tim Powers points out the following comparisons and differences in a research reactor like HFIR and the power reactors in the threatened Japan complexes.


•HFIR operates at 85 megawatts of thermal power; the Fukushima reactors operate at 1,380 megawatts.

•HFIR produces a small amount of power for a short time between refueling while the Fukushima reactors are designed to produce large amounts of power for a long time between refueling; as a result the Fukushima reactor core has approximately 1,000 times more mass than the HFIR core.

•HFIR operates at 155 degrees Fahrenheit; the Fukushima reactor operates at 500 degrees F.

•HFIR does not require on-site or off-site AC power or diesel power to remove decay heat: Batteries provide power for primary coolant circulation for 12 hours after shutdown, and then no power is required at all. The Fukushima reactors require continuous forced cooling and can tolerate a loss of AC power for only a short time.

•The HFIR reactor vessel is surrounded by the reactor pool, which can absorb all of the reactor decay heat if required, while the Fukushima reactors require active heat removal using pumps and motors.
It was the loss of the emergency generators and subsequent loss of AC power to the Fukushima coolant pumps that led to the overheating of their fuel assemblies. The reactors automatically shut down and were being successfully cooled after the earthquake. The tsunami damaged the emergency generators and ultimately interrupted cooling to the reactors.

Earthquake hazards were taken into account in HFIR's design; the facility is designed to withstand forces that roughly translate to a 6 or 7 Richter scale quake. The largest quake in East Tennessee in modern times was a 4.6 tremor in October 1973.





SNS:

Neutron Sciences ALD Ian Anderson says Japanese officials haven't yet accessed the spallation neutron source at the Japan Proton Accelerator Research Facility Complex. The facility, which is in the quake-affected part of the country, was thought to be damaged in the tremor, although buildings appeared to have withstood the tremors. No one at the J-PARC facility was injured. PhysicsWorld has an update on the status of J-PARC.

ORNL's Spallation Neutron Source was constructed to withstand a quake above 7.0 in the Richter scale range, which would be considered a 2,500-year event, Ian says. The New Madrid quakes of 1811-12, which are considered fairly cataclysmic for the Southeast region, are now thought to have been no greater than 7 in strength.

Because the SNS is accelerator based, the risk of a radioactive fuel meltdown isn't present.

"The SNS was designed to prevent damage to staff, the public and the environment," Ian says. " In the event of an earthquake the accelerator itself would safely switch off. The radioactive inventory at the SNS is contained in the mercury target. Conservative analyses conducted for an earthquake greater than the New Madrid event, even with a concomitant fire, show that no impacts to staff, the public or the environment would occur."


JUSTIPEN Workshop: The fifth LACM-EFES-JUSTIPEN (Japan-U.S. Theory Institute for Physics with Exotic Nuclei) Workshop is going on as planned Tuesday through Thursday at the Joint Institute for Heavy Ion Research. ORNL's Witek Nazarewicz says some attendees from Japan had to cancel because power is interrupted to their physics facilities. However, organizer Takaharu Otsuka will be at ORNL on Wednesday for a half day of the meeting.

"This is an example of our Japanese colleagues' dedication to international scientific collaboration and to their resiliency," Witek says.

[GH85Carrera]

What is a ORNL and a HFIR?

[dhoward]

Originally Posted by GH85Carrera

What is a ORNL and a HFIR?

HFIR? Dr. Hffffffuhrrr?

[kaisen]

Originally Posted by dhoward

HFIR? Dr. Hffffffuhrrr?

[Hugh R]

oak Ridge National Labs

[krystar]

?

[Eric Coffey]

Originally Posted by BK911

ORNL's research faciliity, the High Flux Isotope Reactor.

•HFIR operates at 85 megawatts of thermal power

Great Scott!

[IROC]

Originally Posted by BK911

"The SNS was designed to prevent damage to staff, the public and the environment," Ian says. " In the event of an earthquake the accelerator itself would safely switch off. The radioactive inventory at the SNS is contained in the mercury target. Conservative analyses conducted for an earthquake greater than the New Madrid event, even with a concomitant fire, show that no impacts to staff, the public or the environment would occur."

Coincidentally, here's a picture of the mercury target I took today on my cell phone (through a 1m thick shielded window):

[kach22i]

We have a mini plant on the North Campus of U of M.

I think you get more radiation walking by in full sunlight than if you were to stand on the reactor.

[IROC]

Originally Posted by kach22i

We have a mini plant on the North Campus of U of M.

I think you get more radiation walking by in full sunlight than if you were to stand on the reactor.

Michigan State is where the fun stuff is going to be... Google "FRIB"...

[RWebb]

Mike did you guys get the new small nuke that was in the Obama budget at one time?

[IROC]

Originally Posted by RWebb

Mike did you guys get the new small nuke that was in the Obama budget at one time?

Not yet... Fingers are crossed.