04.03.2011
Non Orthodox Means and Methods to achieve Radiation barriers and establish minimum of ALARA
I realize this particular means and method would be a nightmare at a nuclear plant under normal circumstances. This is also why I feel it may be overlooked as a viable option of attaining radiological barriers, contaminated material encapsulation, structural repair, and stopping water flow.
Gunite with lead for use as a radiological barrier
Lead lined cement blocks are currently in use at nuclear powerplants as a radiological barrier. What I propose is using crushed lead as an admix to gunite and making seamless leadlined walls as a barrier to radiation.
Another application may be Boric acid as an additive for use in encapsulation of contaminated debris to retard nuclear action.
The greatest concern with gunite is the pressure the material is applied with. This can be mitigated to a degree by using a watersoftener first or gluelike encapsulant such as used in asbestos encapsulation projects. It binds dust and small particles to larger less mobile particles. To a degree the shooting pressure can be adjusted down.
The gunite itself is a "shot" formless application of concrete. The methodology lends itself to ALARA because most of the material handlers can be if need be 1000-1500 ft away limiting exposures.
The process itself can be set up in 20-40 minutes and gain 100 wall feet of radiological coverage up to 6 ft height in less than 2 hours. If sigunite or baking soda is used as an admix the work time to initial hardening drops to 15 minutes and the rest of the desired wall height can be gained in a second pass.
Wall thickness freeform can be between - inch to a maximum of 4 inches. Personally I have been in situations where we needed and gained 1ft of thickness in 2 passes.
With lead as an admix as soon as the nozzleman shoots a large enough section to stand behind he is shielded as well as the process will allow. Lead has no set or wait time. He can then shoot the remainder from behind the leading edge of the radiation barrier.
The process if started from the outside walls and worked inward will multiply the barrier effects as soon as the next parallel wall inside is covered. Instead of four inches of coverage the next parallel wall makes it 8 inches. The third one in makes 12 inches of leadlined coverage. The importance of this is simple ALARA. As workers are traveling to projects any decrease in radiation will make it more tolerable and hopefully livable.
Encapsulation
Shot gunite will adhere to most surfaces including metal.
Gunite lends itself with an admix/nuclear action retarder to encapsulation. The mix itself can be made almost nonporous or very friable depending on needs. This while not a deconning method may provide enough breathing room so workers may continue with the truly necessary work in front of them. Depending on the contamination levels it may provide relatively quick foot access to areas that would otherwise need to be cleaned first.
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