D&D Technologies

1. D&D Technologies • Technologies are classified broadly as: • Decontamination • Equipment removal and size reduction • Demolition

2. Decontamination Used to reduce occupational exposure Reduce potential for release of material Reduce potential for uptake of material Permit the reuse of selected components

3. Decontamination Facilitate management of the waste generated Decision to decontaminate must be weighed against the total dose and the cost Always preceded by a careful radiological survey of the facility

4. Decontamination Techniques • Selection criteria • Cost • Surface layer thickness to be removed • Final end state of material surface • Decontamination aim • Allowed dose to decontamination personnel • Amount of secondary waste generated and treatment required

5. Decontamination Techniques • Techniques are primarily characterized as: - chemical - mechanical

6. Decontamination Chemical - Uses concentrated or dilute solvents in contact with the contaminated surface Mechanical – physical techniques that generally clean the surface and/or remove the surface May be used together or separately depending on the situation

7. Chemical Decontamination Water or steam Strong mineral acids Acid salts Weak acids Alkaline salts Complexing agents Oxidizing agents Reducing agents Detergents Surfactants Organic solvents

8. Chemical Decontamination-Advantages Can be used for inaccessible surfaces Generally requires fewer work hours Can decontaminate equipment in place Often can be performed remotely Produces few airborne hazards Uses chemicals that are readily available Wastes produced can be handled remotely Allows recycling of wash liquors (after processing)

9. Chemical Decontamination-Disadvantages Not usually effective on porous surfaces Can produce large volumes of waste May generate mixed wastes Can result in corrosion and safety problems when misapplied

10. Chemical Decontamination-Disadvantages Requires different reagents for different surfaces Requires drainage control May require construction of chemical storage and collection systems for large jobs May require addressing criticality concerns

11. Mechanical Decontamination CO2 blasting Wet ice blasting Hydroblasting Shot blasting Grinding Scarifiers Drill and spall Plasma torch Paving breaker Chipping hammer Scabbling

12. Mechanical Decontamination - Advantages Physical technique involving removal of surface Usually very fast High decontamination factors Effective for large areas

13. Mechanical Decontamination - Disadvantages Work piece must be accessible Crevices and corners are hard to decontaminate Creates airborne dusts May require construction of enclosures to control area

14. Acceptable Surface Contamination Levels - USNRC U-nat, U-235, U-238 and associated decay products Average* – 5,000 dpm/100 cm2 Maximum* – 15,000 dpm/100 cm2 Removable – 1,000 dpm/100 cm2 * Dose rate from beta and gamma-emitters should not exceed 0.2 mrad/h at 1 cm and 1.0 mrad/h at 1 cm, respectively.

15. Acceptable Surface Contamination Levels - USNRC Transuranics, Ra-226, Ra-228, Th-230, Th-228, Pa-231, Ac-227, I-125, I-129 Average* – 100 dpm/100 cm2 Maximum* – 300 dpm/100 cm2 Removable – 20 dpm/100 cm2 * Dose rate from beta and gamma-emitters should not exceed 0.2 mrad/h at 1 cm and 1.0 mrad/h at 1 cm, respectively.

16. Acceptable Surface Contamination Levels - USNRC Th-nat, Th-232, Sr-90, Ra-223, Ra-224, U-232, I-126, I-131, I-133 Average* – 1,000 dpm/100 cm2 Maximum* – 3,000 dpm/100 cm2 Removable – 200 dpm/100 cm2 * Dose rate from beta and gamma-emitters should not exceed 0.2 mrad/h at 1 cm and 1.0 mrad/h at 1 cm, respectively.

17. Acceptable Surface Contamination Levels - USNRC Beta-gamma emitters (nuclides with decay modes other than alpha emission and spontaneous fission) except Sr-90 and others noted previously Average* – 5,000 dpm /100 cm2 Maximum* – 15,000 dpm  /100 cm2 Removable – 1,000 dpm  /100 cm2 * Dose rate from beta and gamma-emitters should not exceed 0.2 mrad/h at 1 cm and 1.0 mrad/h at 1 cm, respectively.

18. Equipment Removal and SizeReduction Physical dismantling and segmenting of equipment such as piping, pumps, tanks, hot cells, laboratories, etc. Technique classes Mechanical Thermal Other

19. Equipment Removal and Size Reduction Removal method must consider: Radiological criteria Availability or adaptability of suitable equipment Knowledge of problems to be tackled Time available to complete tasks Cost-effectiveness of method

20. Equipment Removal and Size Reduction Equipment chosen should be: Easy to use Familiar to the workforce Reliable Well constructed Proven technology Adaptable to remote use

21. Examples Power nibblers and shears Conventional mechanical saws Circular cutters Abrasive cutters Plasma arc cutting Oxygen cutting Flame cutting

22. Demolition Controlled blasting Wrecking ball or slab Backhoe-mounted rams Rock splitter Bristar demolition compound Paving breakers Chipping hammers

23. Protective Clothing Appropriate for radiation exposure Leaded gloves Leaded aprons Protective eyewear Other devices Anti-contamination clothing May be effective for certain radiations

24. Internal Radiation Exposure Control Internal radiation dose control Contamination control program Internal radiation dosimetry Monitoring and surveillance programs Protective equipment and devices Records

25. Contamination Control Program Use of exposure time Engineering controls Access control and alarm systems Radiation safety procedures Radiation work permits (RWP) Work and exposure planning Dose reduction activities (ALARA)

26. Control of Low-level Radioactive Waste Minimizing the production of waste Decontamination and reuse of tools and equipment Collecting, sorting, and classifying waste Radioactive waste volume reduction Storage, disposal and recycling of waste Records

27. Contamination Control • Dry method –wipe off • Tape press- physically remove • Wash with water/ soap • Sweat it out- wear glove sweating action will work contamination out • More aggressive actions

28. Questions?