Scientists reenter Soudan Underground Laboratory

Update March 31, 2011:

Scientists are making progress with their assessment of the status of the CDMS and MINOS experiments in the Soudan Underground Laboratory. But power is still out in the MINOS cavern due to a damaged power feed into the laboratory.

Scientists inspected the MINOS detector on Wednesday, March 30. They found residue of fire-fighting foam, used to extinguish the fire in the shaft, across large parts of the MINOS cavern’s floor. No water or foam got on the connectors of the MINOS experiments’ electronics, but scientists discovered that they need to dry out the lowest part of the experiment’s large electromagnetic coil, which provides the experiment with a magnetic field for particle identification. A part of the coil runs through a shallow trench, which partially filled with water. The inspection of other parts of the experiment is ongoing.

“There are still some unknowns, and we don’t know how long it will take for the laboratory to be fully functional again,” said Rob Plunkett, co-spokesperson for the MINOS experiment. “The good news is that there seems to be very little damage to the experiments.”

CDMS scientists have had limited power to their experiment since Monday, March 28.They have found no problems with their particle detector. All cryogenic systems work as designed, and scientists expect the rest of the equipment to be fine, too.

Cleanup work and repairs continue in the access shaft of the mine. When complete, electricians will install a new power cable between the mine’s level 22 and the underground laboratory, which is located on level 27. The new cable is necessary to restore full power to the laboratory.

Update March 29, 2011:

The first scientists returned to the Soudan Underground Laboratory on March 28 as electricians began to restore power to the laboratory. It was the first time that lights in the laboratory were back on since March 17, when a fire protection system shut down the power to the entire laboratory because of a fire in the access shaft.

The laboratory so far only receives limited power since crews still need to test the electrical system and replace a backup power cable. In the next couple of days, scientists will carry out a thorough investigation of the status of the two major experiments in the laboratory: MINOS and CDMS. The MINOS hall was still without power on March 28.

CDMS scientists have begun to assess the status of their experiment's cryogenic system, which cools ultra-sensitive particle detectors to less than one Kelvin, close to absolute zero temperature. The experiment has warmed to room temperature without losing vacuum, which gives hope that the cryogenics system was undamaged by the long power outage.

Update March 25, 2011:

No further information about the status of the MINOS far detector or the detector of the CDMS experiment is available. We will update this page when scientists can enter the Soudan Underground Laboratory and evaluate the detectors.

Update from the Minnesota Department of Natural Resources on Wednesday, March 23, 2011:

Electricians restored power to the lowest level of the mine at Soudan Underground Mine State Park near Tower, Minn., at approximately 5:45 p.m. Tuesday. Power was needed to run the sump pump at that level to prevent flooding of the Soudan Underground Laboratory. Three other sump pumps, located at higher levels, were activated on Sunday and have been removing a majority of the water from the top two-thirds of the mine since then.

A crew that descended into the mine on Wednesday morning confirmed that the power was still on, all of the pumps were still working, and there were no visible signs of flooding. The crew did not see any smoke or smoldering timbers, but the volume of foam remaining in the shaft from firefighting efforts earlier in the week continues to limit visibility, so it remains difficult for the Minnesota Department of Natural Resources, which manages the mine, to get a clear picture of the conditions in the mine. The crew also accessed the underground laboratory, which is managed by the University of Minnesota, for the first time since the fire. They discovered foam in the lab and will be assessing the condition of the equipment and experiments.

In the coming days and weeks Minnesota DNR staff, with the assistance of outside experts, will be conducting a thorough investigation to determine the source of the fire and the extent of the damage. Until the investigation is complete, the DNR cannot comment on a possible cause or the cost of repairs.

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Update from Fermilab Today on Monday morning, March 21, 2011:

Over the weekend, the Minnesota Interagency Fire Center provided updates on the situation at the Soudan Underground Mine, which houses two Fermilab experiments. Responders to the mine shaft fire reported Sunday that a fire which began the evening of Thursday, March 17, appears to be out, but they were not able to determine its exact location. The Soudan mine is owned and managed by the Minnesota Department of Natural Resources. The Soudan Underground Laboratory, which is managed by the University of Minnesota, is located on level 27 of the mine, about a half-mile underground. The laboratory houses the far detector for the MINOS neutrino experiment and the detector for the Cryogenic Dark Matter Search experiment.

A three-man team, using the mine's operational elevator, descended slowly into the shaft on Sunday, dropping to level 27 in the mine. It was their first descent into the shaft after thousands of gallons of foam and water had been sprayed into the mine. The team was only able to descend after determining that carbon monoxide levels were safe and underground communications were established with the surface.

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Update from the Minnesota Department of Natural Resources on Sunday evening, March 20, 2011:

Soudan mine fire 99 percent out: Responders to the Soudan mine shaft fire reported Sunday that a fire that began the evening of Thursday, March 17, appears to be out, but they were not able to determine its exact location.

A three-man team, using the mine’s operational elevator, descended slowly into the shaft on Sunday, dropping to the mine’s 27th level. It was their first descent in the shaft after thousands of gallons of foam and water had been sprayed into the mine during the past 48 hours. The team was only able to descend after determining that carbon monoxide levels were safe and underground communications were established with the surface. Their safety equipment included self-contained breathing apparatus and oxygen masks.

The crew did not find any active fire. They started critical sump pumps on levels 12 and 22 and water is flowing from the sump pumps to the surface. The team descended to level 27, which houses the Soudan Underground Laboratory, managed by the University of Minnesota. The crew encountered large amounts of foam. It tested communications from that level, but did not enter the laboratory chamber. Level 27 is the mine’s lowest level and where a third pump is located.

Fire officials will not declare the fire is officially out until its source has been located and any smoldering ashes or embers have been extinguished. Sunday’s inspection did not indicate the location of the fire. The cause has not been determined.

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Update from the Minnesota Department of Natural Resources on Saturday evening, March 19, 2011:

Tests on Saturday showed decreasing amounts of carbon monoxide (CO) in the shaft, indicating fire activity is decreasing. Carbon monoxide is a by-product of combustion.

Hoist operators carefully raised and lowered the cages on Saturday through the mine shaft without meeting any obstructions. The cages have been undamaged by the fire. The ability to raise and lower the cages allowed the staff to send down monitoring equipment, including a CO monitor, temperature gauges and a camera that provided critical information about the condition of the shaft.

The plan for Sunday is to continue to monitor conditions within the mine and begin the process of planning how mine crews will address restoring communications and power throughout the mine. Conducting this work within the underground mine environment requires extreme attention to safety. All decisions must be made with the crew members' safety foremost in the planning.

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Update from the Minnesota Department of Natural Resources on March 19, 2011:

Fire fighting operations being directed into the shaft at the Soudan Underground Mine State Park continued throughout the night. Firefighters sprayed firefighting foam and water into the mine shaft. A total of 500 gallons of foam mixed with 50,000 gallons of water was used. This morning carbon monoxide (CO) gas levels, a by-product of combustion, continued to drop significantly, making firefighters hopeful the fire has diminished. The cover was replaced on the shaft when foaming operations were completed.

The University of Minnesota has calculated how much water will be a threat to the Soudan Underground Laboratory. A total of 244,500 gallons would bring levels to the door of the lab. Before the power went out in the mine, the sump pumps were pumping about 35,000 gallon per day.

About 30 people are on site working with the suppression efforts and the Incident Management Team, to protect approximately $50 million to $100 million worth of testing equipment.

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Photos of last night's operations are available on the web at http://www.mnics.org/wpress/.

A virtual tour and more information on Soudan Underground Mine State Park is available at www.dnr.state.mn.us/state_parks/soudan_underground_mine

From the Minnesota Department of Natural Resources press release on March 18, 2011:

Minnesota Department of Natural Resources (DNR) and the Minnesota Interagency Fire Center (MIFC) are responding to a fire that has been detected inside the mine shaft at Soudan Underground Mine State Park near Tower, Minn.

There have been no injuries or loss of life due to the fire. It does not pose a risk to nearby communities or the environment.

DNR officials said they believe the fire is burning inside the shaft between the 23rd and 25th levels of the mine, which is operated as a state park. The mine is also the site of a physics experiment being conducted by the University of Minnesota at the 27th level of the mine shaft.

An incident management team is being sent to the scene by MIFC. No firefighters or DNR personnel are currently fighting the fire because local crews are not trained to fight underground fires. The DNR is seeking additional resources from the mining industry to help put out the fire.

Read the full press release