Sago Lightning And International Coal Group
The Sandia Report is a sharp paper cut in some circles and I as a former hard rock miner have decided to add to this discussion:
The ICG had been cited several hundred times previous to this at this portal alone for willfull violations/citations of Mine Safety and Health Administration laws per CFR title 39 regulations regulating surface and underground mining.
Considering the ICG's past history of violations involving poor ventilation, allowing coal dust to accumulate rather than cleaning it up, methane gas buildups and many others including poor record keeping and poor electrical installations -larger clearances than allowed by law for electrical cabinets and others, the Sandia work is not really of any benefit since:
It has been determined that the gas buildup and resulting explosion occured as a result of a stopping/wall sealing an abandoned area of the old mine failing as it was poorly constructed with "Omega Blocks" and the air wall was of inadequate thickness to absorb the blast not double thickness.
Also since most of the self rescuers were determined not to be defective It leads me to think in all sincerity that these men were not properly trained in their use of the self rescuers. After the siunshine mine disaster in 1968 a lot of miners were given the self rescuers and not even trained in thier proper use!!!!!!!!
If the mine ventilation was proper and adequate and the abandonded areas were left open to ventilate rather than accumulate gasses due to closure and rock dusting was done on a regular basis throughout the mine along with cleaning up the mine as is required the accident would not have happened.
Unfortunately for them the dead miners families are the ones who are left to debate the issue.
lzaharis ■
Re: The Sago Mine Disaster
the source of ignition might have been lightning , but the conditions for the disaster to happen were there waiting for a source.
I concurr with Izaharis .
Marco ■
The Sago Mine Disaster
May 29, 2007
Sandia research indicates that lightning was the likely cause of Sago Mine explosion
Labs’ research makes way into official report
ALBUQUERQUE, N.M. — Findings of a research team from Sandia National Laboratories were a key source of a recently released report by the U.S. Mine Safety and Health Administration (MSHA) indicating that lightning was the likely cause of the explosion in the Sago Mine on Jan. 2, 2006. The disaster killed 12 miners.
As part of its official investigation, MSHA contracted with Sandia to study if energy from a lightning strike could travel underground to potentially ignite an explosive mixture of methane gas trapped in a sealed section of the Sago mine. Three lightning strikes were recorded by national detection networks, along with eyewitness accounts of other strikes nearby the mine, just prior to the explosion. The bolts struck simultaneously with the explosion that was registered by nearby seismographs.
Sandia is a National Nuclear Security Administration (NNSA) laboratory.
Operations at the mine were officially idled in late March by mine owner International Coal Group Inc. A small crew remains employed at Sago to maintain the mine infrastructure.
In early November a Sandia team took its monitoring test equipment across the country to the Sago Mine, located near Buckhannon, W.Va. They spent 10 days analyzing the likelihood that electric current produced by a lightning strike could transmit effects deep into the coal mine.
Their findings became part of the final MSHA accident investigation report delivered to members of Congress on May 9.
“We never expected to discover a smoking gun, but we came as close to this as you can in this type of investigation,” says Larry Schneider, senior manager of Sandia’s Pulsed Power Technology Department. “However, we pursued and characterized a coupling mechanism that the team of accident investigators hadn’t previously considered — that current from a surface lightning strike can generate electromagnetic fields that can readily propagate through the earth, as opposed to current being driven into conductors entering the mine such as metal rails or power lines. Our findings had profound implications.”
MSHA — aware of Sandia’s decades of work studying lightning, particularly how it might impact critical nuclear weapons facilities at the Department of Energy Pantex Plant located outside Amarillo and underground facilities at the Nevada Test Site — asked the team to conduct the experiments and analysis.
“Accident investigators had been suspicious all along that lightning was the cause of the explosion, but there had been no definite proof one way or the other,” says Michele Caldwell, manager of Sandia’s Electromagnetic Qualification and Engineering Department.
Twenty-nine miners were underground at Sago when the explosion occurred. Thirteen were in close proximity to the underground blast when it occurred. One miner died close to the ruptured seal, and 12 others retreated behind a curtain at the working face of the mine in an attempt to barricade themselves against the smoke and carbon monoxide. They awaited rescue there, which would come too late for all but one of them.
With lightning as a potential cause for the Sago Mine explosion, the Sandia team investigated two modes of transmitting lightning energy deep into the coal mine, Caldwell says.
The first mode was direct attachment onto metallic penetrations — such as conveyers used to extract the coal, rails used for transporting people and equipment — and power and communication lines from the entrance to deep inside the mine. The second mode investigated energy propagating through the earth’s surface from the point of a surface lightning strike or overhead arc channel.
“We needed to be able to make measurements without waiting for or triggering a true lightning strike in the vicinity, so we provided our own drive signal,” Caldwell says. “To prevent interference with mine operations or introduction of a safety hazard, we injected a small, continuous signal over a range of frequencies present in a lightning strike as a drive source.”
For the metallic penetrations, the drive signal was applied at the entrance to the mine and signals were measured with current and voltage probes at various points in the mine, as far as two miles in. The drive signal was transmitted by fiber optics to the entrance of the mine as the instrumentation was carried inside the mine to make measurements. The goal was to see how much the signals decreased as a function of the distance from the entrance of the mine.
For measuring propagation of lightning energy from the surface of the earth to the mine cavern 300 feet below, the drive signal was applied to a long wire stretched on the surface. Directly below, inside the mine, an antenna was set up to pick up the transmitted signals. Multiple antenna measurements were made, covering a cross pattern in the mine of about 80 meters by 80 meters. The measurements were compared to analytical models simulating lightning field propagation through the earth.
The data was used to develop transfer functions, a way of understanding how much energy penetrated into the mine based on a surface lightning events. These results were combined with a theoretical lightning strike waveform to determine if voltages get high enough inside the mine to be of concern.
The study concluded that it was highly unlikely that lightning initiated the explosion by traveling along conductors through the mine and into the sealed area. However, electromagnetic energy from a significant lightning event close to the sealed area could travel through the ground at Sago and induce a high voltage into metallic conductors that were left in the sealed section of the mine. A pump cable was left abandoned at the ignition point. This cable was found by MSHA investigators to have many damaged sections that could provide a spark when the cable is subjected to high voltages. A spark is a known ignition source of flammable methane mixtures that can accumulate in sealed sections of mines.
“The results of field measurements and analytical modeling were clear; lightning can propagate significant electrical energy into mine systems under the right conditions,” says Schneider. “The team’s work at Sago was only a brief, but powerful look into this effect. We need to better understand this phenomenon in the variety of scenarios seen in the US mining system and bring to bear other state-of-the-art tools, including our advanced computing capabilities. I can readily envision this leading to additional, reasonable preventative measures to reduce the probability of such a catastrophic event in the future. This is an important message.”
Schneider says he is grateful for Sandia’s relationship with MSHA.
“I need to compliment MSHA for their engagement of Sandia,” he says. “The techniques we used in our work for them were not generally understood outside of the nuclear weapons community. It took technical insight and courage on their part to embrace this work. We’re very pleased that Sandia played an important role in this investigation.”
MSHA’s investigation report of the Sago Mine accident is online at
href="http://www.msha.gov." target="blank">www.msha.gov.
Photo:
Sandian Dawna Charley, left, and a
Sago miner work with a vehicle,
called a “mantrip,” before it enters
the mine as part of experiments the
Labs personnel conducted at the
site last November.
Attachments
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The Sago Mine Disaster
Sandia researchers study possibility that lightning was cause of Sago Mine disaster
Team visits mine to conduct experiments
ALBUQUERQUE, N.M. — In early November a research team from Sandia National Laboratories visited the Sago Mine near Buckhannon, W.Va. to study the possibility that lightning was the cause of the Jan. 2, 2006 explosion that killed 12 miners.
The researchers took their monitoring equipment across country and spent 10 days analyzing the likelihood that electric current produced by a lightning strike transmitted effects deep into the coal mine, resulting in the tragedy.
What they found has the potential to set new standards for lightning protection in the U.S. mining industry.
“We never expected to discover a smoking gun, nor did we,” says Larry Schneider, senior manager of Sandia’s Electromagnetic, Stockpile Support and Work for Others Department. “However, we did characterize a coupling mechanism that the team of accident investigators hadn’t pursued — that current from a surface lightning strike can generate electromagnetic fields that can readily propagate through the earth, as opposed to current being driven into conductors entering the mine such as metal rails or power lines. The correlation between our field measurements and analytical models is quite impressive. Significant energy can be transmitted deep into the mine without physical conductors being present on or near the surface. This has profound implications.”
The Sandians, including Matt Higgins, Dawna Charley and Leonard Martinez conducted the experiments at the mine with support from Marv Morris, a contracted consultant and former Sandian. Higgins, Charley and Martinez worked at the site from Nov. 1-10.
Sandia is a National Nuclear Security Administration (NNSA) laboratory.
The Mine Safety and Health Administration (MSHA) — aware of Sandia’s decade of work studying lightning, particularly how it might impact critical facilities at the Pantex Plant located outside Amarillo and underground facilities at the Nevada Test Site — requested the team to conduct the experiments.
MSHA is charged with writing a report on possible causes of the deadly explosion that should be completed sometime near the one-year anniversary of the event. They intend to include in their report data and analysis from Sandia’s investigations.
“Accident investigators have been suspicious all along that lightning was the cause of the explosion, but there has been no definite proof one way or the other,” Michele Caldwell, manager of Sandia’s Electromagnetic Qualification and Engineering Department, says.
Multiple lightning strikes, including one of much greater than normal power, were recorded within a five-mile radius of the mine entry point on Jan. 2, 2006 at about 6:26 a.m. At virtually the exact same instant, methane ignited in a recently sealed area of the mine, blowing out the seals and filling it with smoke, debris, fumes, and lethal levels of carbon monoxide. Accident investigators are not sure of the cause of the methane ignition and haven’t resolved how the lightning energy might have entered the recently sealed area.
Twenty-nine miners were underground at Sago when the explosion occurred. Thirteen were in close proximity to the blast. As was later learned, the force of the explosion killed one miner, and 12 others retreated behind a curtain at the working face of the mine in an attempt to barricade themselves against the smoke and carbon monoxide. They awaited rescue there, which would come too late for all but one of them.
With lightning as a potential cause for the Sago Mine explosion, the Sandia team investigated two modes of transmitting lightning energy deep into the coal mine, Caldwell says.
The first mode was direct attachment onto metallic penetrations — such as conveyers used to extract the coal, rails used for transporting people and equipment — and power and communication lines from the entrance to deep inside the mine. The second was propagating energy through the earth’s surface from the point of a surface lightning strike or near-by arc channel.
“We needed to be able to make measurements without waiting for or triggering a true lightning strike in the vicinity, so we needed to provide our own drive signal,” Caldwell says. “To prevent interference with mine operations or introduction of a safety hazard, we injected a small, continuous signal over a range of frequencies present in a lightning strike as a drive source.”
For the metallic penetrations, the drive signal was applied at the entrance to the mine and signals were measured with current and voltage probes at various points in the mine, as far as two miles in. The drive signal was transmitted by fiber optics to the entrance of the mine as the instrumentation was carried into the mine to also make measurements. The goal was to see how much the signals attenuated as a function of the distance of the drive signal. The measurements will be compared to transmission line models of the penetrations developed by Sandia.
For measuring propagation of lightning energy from the surface of the earth to the mine cavern 300 feet below, the drive signal was applied to a long wire stretched on the surface. Directly below inside the mine, an antenna was set up to pick up the transmitted signals. Multiple antenna measurements were made, covering a cross pattern in the mine of about 80 meters by 80 meters. The measurements were compared to analytical models simulating lightning field propagation through the earth.
The data will be used to develop electrical transfer functions, which can be combined with a theoretical lightning strike to determine if voltages get high enough inside the mine to be of concern.
Schneider says this study of the Sago Mine accident was a “short term program to identify, characterize, and quantify through measurement of the electromagnetic coupling paths of lightning into the sealed area of the Sago underground coal mine and to compare these levels to those that would be required to initiate an explosion.”
“The hope after this initial program is that we will continue to work with MSHA to build a national program to prevent these deadly events from occurring in the future,” Schneider says.
For more information, please visit:
https://edir.bulk-online.com/profile...boratories.htm
Photo: Long distance view of the Sago Mine
Attachments
sandia_sago (JPG)
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