A health physics technician (HPT) discovered that a scaler in an analytical laboratory was out of P-10 gas (90%Ar and 10% CH4). The HPT went to the building where auxiliary gas cylinders are stored. He located a P-10 gas cylinder and turned to search for a hand-cart. There were no hand-carts present, and the technician had to get one from another room. When he returned to the cylinder storage area, he loaded the wrong cylinder. It contained hydrogen gas instead, however, the two cylinders were next to each other and they were basically identical. The empty cylinder was then replaced by the full one and the scaler was purged for several minutes before it was used. The alpha channel worked well, however, the beta channel did not respond. An instrument technician was contacted to identify view more
A liquid hydrogen neutron moderator developed a leak between the canister that contains liquid hydrogen and the insulating vacuum jacket.
The moderator assembly consists of an exterior metal vacuum jacket with an interior metal transfer line and canister that contain liquid hydrogen. The moderator canister is constructed of aluminum and is approximately five inches wide, five inches high, and two inches deep. The liquid hydrogen supply lines to the moderator canister are constructed of stainless steel. The operating temperature of the moderator varies from -420 degrees Fahrenheit to a possible 300 degrees Fahrenheit. Mechanical operators discovered a leak following a cleaning operation on the moderator. The cleaning operation was performed to remove impurities that could freeze view more
During a facility walk-through, it was noted that a combustible gas (hydrogen) monitoring system installed in a furnace room was inoperable (the system had been unplugged). This system is used to detect and warn facility employees of an explosive or flammable environment. An explosive or flammable environment can only occur if there is a leak in the system, which would not be expected to occur during normal operations. When the system was reactivated, no leaks were indicated.
The incident had the following three causes:
A procedure describing administrative controls necessary to ensure safe operations in the area should have been developed and implemented prior to disabling the hydrogen monitoring system.
The hydrogen monitor was not hard-wired, which allowed it view more
A hydrogen monitor leak detector (HMLD) was out of service because of a failed membrane. The HMLD heater circuit and the ion pump and its associated controller were de-energized and red-tagged to ensure the system remained shut down. The ion pump and controller were later found energized. The ion pump circuit is a low-power (120-V, 1 amp) circuit and the pump operates in the micro-amp range. There was no damage to equipment from this inadvertent energization. There was also no personnel safety hazard since the tag out was not for maintenance purposes and since the system was in its normal operating configuration.
The direct cause is listed as personnel error, inattention to detail. This category most closely describes the inadvertent actuation of the controller toggle switch. view more
A routine security patrol reported a strong odor of sulfur coming from a battery charging facility. The battery charging facility is used for charging the various forklift batteries for the shipping and receiving operation. The building is approximately 450 sq. ft. and has four charging stations. Emergency response was initiated and the incident commander responded to the scene. Initial air monitoring indicated readings above the Lower Explosive Limit (LEL) for hydrogen gas. The local fire department responded and setup for the situation. Facilities personnel responded and turned power off to the building. The building was ventilated and verified to be safe by the fire department. There were no injuries or damage.
The exhaust fan for the building failed, allowing hydrogen gas to view more
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