Urethane Foam Void Filling
Category: Dismantlement > Non-Cutting Methods > Void Filling
Reference # : OST No 1816 , DOE/EM-0395 Model No : UFVF
The void filling technology entails filling hollow spaces within D&D debris with a fluid material that hardens on standing cap. The concept behind this technology application was that vessel void spaces would be filled with a pumpable material that once solidified would be capable of withstanding the compressive load resulting from the overburden. Thus should the vessel's wall/shell degrade (i.e., rust) and fail over time, the solid void filling media would prevent subsidence of the OSDF cap.
This particular demonstration used expanded polyurethane foam as the void filling media. The polyurethane is produced by mixing two chemicals, polymeric diphenylmethane diisocyanate (MDI), which is the base ingredient for any polyurethane foam. The other ingredient is plyol blend. MDI is toxic and presents definite health hazard. However, once mixed with the second chemical component, the resulting polyurethane foam is non-toxic and safe for land disposal.
The two chemicals are kept separate until they reach the mixing gun from which the mixture is immediately ejected in to the vessel. The two chemical ingredients leave the mixing gun as a liquid stream and shortly thereafter start to expand into a 'foam'. The speed at which the liquid expands to form the foam can be controlled through regulating both the temperatures of the two chemical components and their ratio to one another. These parameters also determine the compressive strength of the foam after it hardens therefore knowledge of the process parameters and equipment is essential. The foam in its liquid phase was allowed to expand to its maximum extent before the addition of more of the liquid mixture.
Dimensions of Tech Model (LxWxH): Mixing control Unit :
22 inches X 40 inches X 47 inches
Weight of Tech Model (lb): 425
Reduces risk to laborers from segmenting work related injuries
Reduced work duration, economics, and overall D&D schedule. Void filling produces considerably less airborne contamination than segmentation. Void filling generated minimal traces of toxic MDI vapor.
Reduce worker health and safety risks, and personal protective equipment requirements.
Void filling is not a feasible option when components are simply too large or too heavy to be removed from building intact.
The density and added weight of the selected void filling medium were therefore major concerns.
The void filling technology using expanded polyurethane foam performed without any significant technical or mechanical problems during the demonstration and there appears to be no need for future development.
The mixing control unit regulates and pumps chemicals to the mixing gun
Schematic of the expanded polyurethane foam void filling process