Cleaning of radioactive contamination using dry ice

Abstract

A system and method for cleaning components contaminated with radioactive materials uses dry ice blasting to remove the radioactive contaminant from the contaminated component in a chamber including a directed air flow. The removed contaminant is transported by the directed air flow for collection in a filter, which may be configured as a HEPA filter. During the cleaning process, the dry ice used for the blasting process sublimates into gaseous carbon dioxide such that no incremental contaminated cleaning media or residue is generated during decontamination of the component. Because the dry ice is non-corrosive, non-abrasive and environmentally neutral, damage to the component being cleaned and decontaminated is prevented or substantially avoided. Because dry ice sublimates on impact, cleaning of electrical components without compromising electrical function is enabled.

1 . A method of cleaning a component contaminated with a radioactive material, the method comprising:
 containing a component contaminated with a contaminant in a chamber, wherein the contaminant includes a radioactive material;   generating an air flow through the chamber, wherein the air flow outgoing from the chamber is in fluid communication with a filter;   cleaning the contaminant from the component with a dry ice blasting stream configured to remove the contaminant from the component such that the removed contaminant is transported by the air flow to the filter;   filtering the air flow using the filter to entrap the removed contaminant in the filter.   
     
     
         2 . The method of  claim 1 , wherein the filter is configured as a HEPA filter. 
     
     
         3 . The method of  claim 1 , further comprising:
 removing the filter including the entrapped contaminant; and   processing the filter including the entrapped contaminant as low level radioactive waste.   
     
     
         4 . The method of  claim 3 , wherein processing the filter including the entrapped contaminant includes at least one of controlled storage of the filter and controlled disposal of the filter. 
     
     
         5 . The method of  claim 1 , further comprising:
 measuring the radioactivity of the component prior to cleaning; and   measuring the radioactivity of the component after cleaning.   
     
     
         6 . The method of  claim 1 , wherein the chamber is at least partially defined by the component. 
     
     
         7 . The method of  claim 1 , wherein containing the component contaminated with a contaminant in the chamber further includes:
 sealing the chamber to isolate the component.   
     
     
         8 . The method of  claim 1 , wherein filtering the air flow using the filter to entrap the removed contaminant in the air flow further includes:
 filtering the air flow through a plurality of filters to entrap and collect the removed contaminant from the air flow.   
     
     
         9 . The method of  claim 1 , wherein the chamber is defined by a cabinet, the method further comprising:
 positioning the component in the cabinet prior to cleaning the component.   
     
     
         10 . The method of  claim 1 , further comprising:
 providing a dry ice blasting unit in the chamber; and   controlling the dry ice blasting unit to direct the dry ice blasting stream to remove the contaminant from the component.   
     
     
         11 . The method of  claim 1 , wherein cleaning the contaminant with a dry ice blasting stream further includes:
 adjusting one of a dry ice pellet size and a blasting stream velocity of the dry ice blasting stream.   
     
     
         12 . A system for cleaning a component contaminated with a radioactive material, the system comprising:
 a chamber configured to contain a contaminated portion of a component, wherein the contaminated portion is contaminated by a contaminant including a radioactive material;   a dry ice blasting unit configured to provide a blasting stream including dry ice pellets;   an air flow device configured to generate a directed air flow through the chamber and through a filter in fluid communication with the chamber;   wherein the system is configured such that contamination removed from the component by the blasting stream of the dry ice blasting unit is transported by the directed air flow to the filter and entrapped by the filter to clean the component of the contaminant including the radioactive material.   
     
     
         13 . The system of  claim 12 , further comprising:
 a controller in operative communication with the dry ice blasting unit;   wherein the controller is configured to control one or more of a dry ice pellet size, a blasting stream velocity, a blasting nozzle position, and movement of the dry ice blasting unit relative to the component.   
     
     
         14 . The system of  claim 12 , further comprising:
 an incoming air flow passage in fluid communication with the chamber and the air flow device;   an outgoing air flow passage in fluid communication with the chamber and the air flow device; and   the outgoing air flow passage is in fluid communication with the filter.   
     
     
         15 . The system of  claim 12 , wherein the filter is configured as a HEPA filter. 
     
     
         16 . The system of  claim 12 , wherein the filter is configured as a plurality of HEPA filters. 
     
     
         17 . The system of  claim 12 , wherein the dry ice blasting unit is remotely controlled. 
     
     
         18 . The system of  claim 12 , wherein the chamber is defined by a cabinet in fluid communication with the air flow device and the filter. 
     
     
         19 . The system of  claim 12 , wherein the component is defined by one of a duct, pipe, vessel, container, and tank. 
     
     
         20 . The system of  claim 12 , wherein the component is configured as one of a tool, an electrical component, and a component part of a nuclear power plant.