Lesson Learned Statement:Many techniques are available for making radiological work safer and more efficient. This document contains brief descriptions of some collected from past reports from the Hanford ALARA Center. They are compiled here for introduction into the DOE Lessons Learned process.
Discussion:GWP #1: T Plant suppressed airborne contamination while removing material from process cells by occasionally injecting a pressurized mist from a piping header installed at the cell opening. The mist eliminated the airborne contamination and did not create puddles at the bottom of the cell because the low volume of liquid required evaporated quickly. Eight foot bars with four #0.5 nozzles at the cell openings used less than 4.5 gallons per hour.
GWP #2: The Plutonium Finishing Plant is using a new glovebox line that has temporary shielding built into its design. Access to each glove sleeve is through a hinged door that has borated poly installed. There is 1-2" borated poly canned inside 1/2" thick stainless steel throughout the glovebox. Windows are made from leaded glass and there are recesses and garages inside the glovebox to hold products during analysis. The glovebox is shielded on all six sides. Neutron dose outside the glovebox has been reduced by 70% and gamma radiation by 90%. Point-of-Contact for this glovebox design is Terry Merkling at (509) 373-9412.
GWP #3: Workers can reduce their exposure while handling highly radioactive or contaminated materials by using inexpensive commercially available tools. A 32-inch model "EZ-Reacher II" sells for $25.99 and the 40-inch model for $27.99 each. The tools can be used to decontaminate gloveboxes and handle hot samples. The 25-foot model can be used to survey inside Exclusion Areas. Information on these tools can be found at http://www.trisyn.com/ret-cap/ret-ez-cap.htm or by calling (800) 446-6076, extension 18.
GWP #4: The best way to install portable ventilation in containment tents is to place the air supply inlet at least 6 feet above the floor near the entrance. HEPA filters, furnace filters, demand regulators (dampers), or foam are usually installed to filter incoming air. Air travels in a downward path through the anteroom into the work section of the containment. The exhaust ventilation is usually located at floor level opposite the work section entrance door. Air enters the work section at head height and flows downward across the work section. If any airborne contamination is created while removing protective clothing in the anteroom it should flow towards the work section and not out the containment entrance.
GWP #5: Tyvek Homewrap makes excellent catch basins for radioactive work. It will hold liquids and is much more fire retardant than sheet plastic. Tyvek can be purchased in 9 foot rolls in lengths of 100 feet for about $80.00. The material is used on buildings as a vapor barrier.
GWP #6: Clam-shell cutting machines can significantly speed up cutting pipes for welding on a new valve or fitting. Such machines are built in two 180 degree sections that bolt together with four bolts. One section is held under the pipe and the other section is held over the pipe. The bolts are then tightened to hold the tool together. One or two cutting bits should be installed on the machine before attaching it to the pipe so that the only necessary remaining action is to connect the air or electric motor and start the machine. Two cutting bits are used to sever the pipe and cut a bevel on the standing end at the same time. Each revolution of the machine causes the bits to feed in 0.003". Normally the machining takes about three minutes to cut 2-4" diameter piping. If the piping is highly contaminated inside, use the machine until the pipe is cut nearly through and then take the machine off to keep it from becoming contaminated. Complete the cut with a rolling device.
GWP #7: Spent Nuclear Fuels personnel contained contamination during repairs to underwater spent fuel handling manipulators by applying hydraulic oil as a fixative as the manipulators were raised from the pool. The hydraulic oil had already been approved for use in the fuel pool. Two sleeves with a continuous hook-and-loop seal were installed over the arms and opened as needed during the repairs.
GWP #8: To ensure that temporary shielding isn't "disturbed" after it's installed, wrap special tape in a "barber pole" fashion around temporary shielding installations. If the tape is broken, the shielding has shifted or been disturbed.
GWP #9: Fluor Federal Services modified a concrete surface preparation tool to operate submerged in about 3" of water instead of connecting a vacuum cleaner to the shrouded tool. The tool has a pneumatic motor that spins a hub with carbide steel buttons that slap the concrete surface. The steel buttons strip the concrete surface of any paint or sealant. Any airborne contamination is trapped in the water. Use of this tool submerged in 3" of water allows very highly contaminated concrete to be stripped without using a HEPA filtered vacuum cleaner connected to the shroud.
Recommended Actions:Facilities are encouraged to apply these techniques where appropriate to reduce radiological exposure to workers.
Originator:Fluor Hanford, Inc.
Contact:Larry Waggoner (509) 376-0818 or Jerry Eby (509) 372-8961
Name Of Authorized Derivative Classifier:Not required
Name Of Reviewing Official:John Bickford
Priority Descriptor:Green / Good Work Practice
Keywords:ALARA, exposure reduction
References:ALARA Weekly Reports October 2001-February 2002
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DOE Function / Work Categories:Decontamination & Decommissioning
Maintenance - Mechanical
Machining & Fabrication
ISM Category:Feedback and Improvement
Hazard:Personal Injury / Exposure - Radiation / Contamination
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