Lessons Learned

An operator began preparations for a cleaning run, and was unaware that a maintenance task to calibrate a pressure transducer was scheduled to also take place that morning. The calibration required a break on a hydrogen line in order to install a Measuring and Test Equipment (M&TE) gage, which was used in the calibration. At the time the operator was informed of the calibration, the cleaning run procedure had been initiated but the actual cleaning had not yet begun. A discussion between his supervisor and the facility maintenance coordinator resulted in a decision to proceed with the maintenance task and suspend the cleaning run until afterwards.

The operator evacuated the hydrogen line and the hydrogen cylinder was valved out. The maintenance work package procedure had view more

A shop supervisor determined that a second shift would be necessary to complete some priority work on the spare hydrogen mitigation pump. The work scope for the shift would be dedicated to continued fabrication of designed tubing runs, repairs to existing tubing with known leaks and pressure testing of other various tubing runs. The shift craft complement would include three pipe fitters, one welder, one QC inspector and a shift supervisor.

The shift remained under normal operations prior to the event. There had been no existing problem up until the point that craft personnel implemented some hydrostatic pressure testing on some tubing runs on the spare hydrogen mitigation pump. Work activities associated with the hydrostatic testing were to be in accordance with the Hydrostatic view more

A guest student was weighing out less than 200 mg of sodium hydride. The material reacted with moisture in the air, producing hydrogen. The heat of the reaction ignited the hydrogen on the end of the spatula being used to transfer the material and at the mouth of the bag holding the stock material (approximately 48 to 50 g). The student attempted to smother the flames with a cotton lab coat hanging nearby. He quickly determined that the lab coat was insufficient to smother the flames and entered the adjoining lab to get a fire extinguisher and warn other lab workers in the area. The other lab workers exited the lab, warned others in the area, pulled the fire alarm and called the laboratory shift supervisor. The student extinguished the fire with the fire extinguisher, then left the view more

As a prerequisite to a storage tank slurry pump run, a tank operator identified a Lower Flammability Limit (LFL) Analyzer surveillance reading to the control room that was out of limits low. The reading was a negative zero % LFL indication (-0 % LFL). The tank operator roundsheet limits are 0 to 10% LFL. The "null" value (value read on analyzer when air with 0% LFL is drawn through the analyzer) as directed by the LFL Analyzer loop calibration procedure is set between 0 and 4% LFL.

To alert personnel to the buildup of potentially dangerous levels of explosive gases in the tank, a Combustible Gas Detection System is used to monitor and analyze sample air drawn from the tank vapor space. This system consists of a sensing element, a 4-20 milliAmp direct current (mADC) view more

A waste pretreatment tank operator was performing surveillance rounds on a tank and found the Composite Lower Flammability Limit (CLFL) Analyzer sample flow reading 1.4 cubic feet per hour (CFH). The Operational Safety Requirements (OSR) document required flow range is 1.5 CFH to 2.5 CFH. The Limiting Condition for Operation was immediately entered and the tank operator adjusted the flow into the required surveillance range.

The hydrogen and CLFL monitors are used to detect the presence of flammable gases in waste tanks vapor space. Maintaining the concentration of flammable vapors in the tank vapor space below flammability limits maintains tank integrity by preventing the possibility of tank deflagrations. The hydrogen monitors provide an automatic means to monitor flammable view more

A facility replaced the copper tubing used for hydrogen distribution, with stainless steel tubing. This was done to address a fire protection concern related to the solder on the copper tubing being susceptible to heat, melting, and releasing a flammable gas. The facility maintenance personnel completed the replacement, noted the pressure on the hydrogen bottle, and left the building. When the maintenance person returned on the following day, s/he noticed the pressure on the hydrogen bottle had dropped 500 psi overnight, indicating a leak in the system. S/he notified the appropriate facility personnel and together they began to determine why the hydrogen had dropped 500 psi overnight. The hydrogen line originates at a manifold, which is part of a glove box atmosphere purification view more

A pinhole at the base of a hand-held hydrogen torch, allowed hydrogen to leak. In the process of lighting a second torch, the leaking hydrogen was ignited. The operator, being startled by the "pop" of the lighted hydrogen allowed the #2 torch to drop and hang by its hose support approximately 6" from the floor. The hydrogen and oxygen hoses on the #1 torch were burned through and hung approximately 12" from the floor. The free burning #1 hose burned the #2 hydrogen and oxygen hose assembly through, causing both hoses assemblies to burn without valve control. The hose size is 1/4" and is used in various areas of the plant.

An apprentice mechanic lacerated his right forearm while quickly sliding out from under a hydrogen prototype bus when the bus slipped off a hydraulic jack. The apprentice and another mechanic had raised the bus about 1 foot from the ground to position it on jack stands when the hydraulic jack tipped over. The apprentice went to the site medical facility, where he needed five stitches to close the wound in his forearm.

The mechanics were raising the rear of a hydrogen prototype bus, like the one in the figure below, and placing it on jack stands. After chocking the wheels, they used bottle jacks on each side of the rear axle to raise the bus high enough to place a 20-ton hydraulic jack under the differential. With the bus resting on a pair of small jack stands, they raised the view more

A 2000-psia-rated gas cylinder (nominal size 10"x1 1/2") was being filled with hydrogen to a target pressure of 1500 psia. The cylinder suffered a failure at an indicated pressure of 1500 psia during filling. Investigation of the failure subsequently revealed that a faulty digital readout had allowed the cylinder to be over-pressurized. There were no safety consequences due to the failure and no damage to the facility or equipment. The cylinder was being filled in a test vault that was specially designed for the high-pressure burst testing of pressure vessels and components. While no over-pressure cylinders were released from the laboratory for use, this incident is being reported to address the potential and subsequent lessons learned.

Investigations revealed that the view more

An employee noticed an unusual smell in a fuel cell laboratory. A shunt inside experimental equipment overheated and caused insulation on conductors to burn. Flames were approximately one inch high and very localized. The employee de-energized equipment and blew out the flames. No combustible material was in the vicinity of the experiment. The fire was contained within the fuel cell and resulted in no damage to equipment.

The employee was conducting work with a fuel cell supplied by oxygen gas. The hazard control plan (HCP) associated with the work was for use with fuel cells supplied by air or hydrogen, but not for oxygen, which yields a higher current density. The technician had set up the station wiring to handle a current of 100 amps and the shunt was configured to handle a view more