June 25-26, 2002 D&D Lessons Learned Workshop 1

D&D Health Physics Issues

George Ascione / Carl TilsonD&D Lessons Learned Workshop

June 25-26, 2002

PPPL

June 25-26, 2002 D&D Lessons Learned Workshop 2

Overview

• Discussion of the concerns, hazards, and protective measures to reduce or eliminate radiation dose to personnel from internal and external radiation sources associated with the D&D effort.

June 25-26, 2002 D&D Lessons Learned Workshop 3

Topics Of Discussion

• Identification of the internal radiation hazards• Identification of the external radiation hazards• Development of ALARA protective measures for

internal radiation hazards• Development of ALARA practices to reduce or

eliminate the external dose hazard• Decon vs. Disposal• Releasing material and areas• Counting and surveying techniques• Some facts and figures….

June 25-26, 2002 D&D Lessons Learned Workshop 4

Identification Of The Internal Radiation Hazards

• Possible source terms– Tritium

• Elemental (Low Concern)• Oxide (Moderate Concern)• Oxide contaminated particulates (High Concern)

– Atmospheric Dust– Carbon dust– Concrete dust

– Activated metals• Cutting and grinding operations.

June 25-26, 2002 D&D Lessons Learned Workshop 5

Identification Of The External Radiation Hazards

• Possible source terms (cont.)– Tritium

• All Forms, No Concern

– Activated metals• Vacuum Vessel

• Coil Removal and Cutting

• Sheer Compression Panel Removals

June 25-26, 2002 D&D Lessons Learned Workshop 6

ALARA Protective Measures For Internal Radiation Hazards

• Tritium– Oxide and Elemental Form

• Routine HP Technician monitoring using bioassay. D&D worker bioassay monitoring as needed.

– Tritiated particulates• All areas with the potential to have airborne tritiated

particulates required either air supplied respirators or air purifying respirators on all workers.

– All Contamination areas• Varying degrees of protective clothing (PC’s) based on the

level of hazard and defined on the job specific RWP.

June 25-26, 2002 D&D Lessons Learned Workshop 7

Development Of ALARA Practices To Reduce Or Eliminate The

External Dose Hazard

• Standard ALARA Implementation of “TDS” (Time, Distance, and Shielding)– Specific job analysis on activated materials

• Ensuring that the proper personnel perform the task and are properly trained (Time Factor)

• Use of specialized tools and apparatus to maximize the distance between the workers and the source. (Distance Factor)

• Whenever possible rely on local structures for shielding or deploy lead blankets to shield the workers (Shielding Factor)

June 25-26, 2002 D&D Lessons Learned Workshop 8

Development Of ALARA Practices To Reduce Or Eliminate The

External Dose Hazard

• The majority of the external dose received during the D&D effort was the result of the shear compression panel removals.

June 25-26, 2002 D&D Lessons Learned Workshop 9

Decon vs. Disposal

• DOE Moratorium Issues– Scrap metals being removed from TFTR cannot be recycled or

disposed of in normal landfills. The “No Rad Added” directive prohibits recycling at this time.

– All stainless steel components removed from TFTR are treated as activated and disposed of by approved PPPL Rad Waste procedures

• Tritium contaminated items– Equipment and apparatus brought into the test cell for D&D

activities which were never activated became contaminated.– Based on value to the laboratory for internal use, equipment is

being evaluated and released in accordance with PPPL’s release criteria of < 1000 DPM/100cm2

June 25-26, 2002 D&D Lessons Learned Workshop 10

Releasing Material And Areas

• Activated Metals– No release criteria established. All activated metals treated as Rad

Waste

• Tritium contaminated items– PPPL’s release criteria of < 1000 DPM/100cm2– Equipment with oils, hydraulic fluids, cooling liquids and/or other

chemicals• When possible samples are analyzed for tritium.• Systems with cooling components or lubricating oil were flushed to

remove any potential internal contamiation.• Decontamination by manual methods for hundreds of small items

used to rig, hoist, secure, and move materials during D&D.

June 25-26, 2002 D&D Lessons Learned Workshop 11

Releasing Material And Areas (cont.)

Tritium contaminated areas– Floor space which became contaminated areas were

continuously cleaned and moved. Ultimately the plan is to have the test cell floor free from any contamination areas

– Some components and structures associated with TFTR will remain in place in the test cell. These areas and pieces of equipment will be agressively decontaminated to levels below PPPL’s guidelines.

– A significant portion of the test cell including the walls and fire protection system will be manually decontaminated.

June 25-26, 2002 D&D Lessons Learned Workshop 12

Counting And Surveying Techniques

Tritium– Liquid Scintillation (Passive)

• The overwhelming majority of the samples taken were “Q-Tip” samples, gross area surveys.

• Oils and hydraulic fluids were Oxidized when possible and counted using LSC.

• Airborne tritium oxide analysis performed using water bubblers

• Personnel bioassay’s

– Realtime Air Monitoring• “Line Break” activities require local portable tritium monitors

June 25-26, 2002 D&D Lessons Learned Workshop 13

LSC, Real-time Tritium MonitorsAnd Other Handheld Monitors

June 25-26, 2002 D&D Lessons Learned Workshop 14

Oxidizer And Bubblers

June 25-26, 2002 D&D Lessons Learned Workshop 15

Counting And Surveying Techniques (cont.)

Gamma from activated components– Real time monitoring

• Continuous air monitoring using SAIC air filters analyzed with local scalers

• Hand held portable instruments for local activation measurement

• Baseline whole body counting and exit counting

– Passive Monitoring• Personnel dosimetry

• Gamma Spectroscopy performed on metals and metal filings

June 25-26, 2002 D&D Lessons Learned Workshop 16

Whole Body Counting AndGamma Spectroscopy

June 25-26, 2002 D&D Lessons Learned Workshop 17

Some Facts And Figures….

• “0” Zero reportable occurrence reports due to health physics related issues based on regulatory requirements.

• < 100 mRem combined dose from internal exposure for all HP technicians and workers monitored for D&D operations

• Maximum single individual external dose of 573 mRem attributed to the sheer compression panel removals.

• “0” Zero detectible internal exposures due to activated metals to date.

• More than 150,000 individual LSC samples analyzed.

• Just over 210Ci of tritium total for the site released up the stack since August 2001

June 25-26, 2002 D&D Lessons Learned Workshop 18

More Facts And Figures

Enclosure lift contamination levels (Maximum) 600,000 dpm/100cm2

Segment pull maximum airborne contamination (Segment Top) 1.90 microCuries/m3

Segment pull maximum airborne contamination (100’ Level) 0.32 microCuries/m3

Maximum contamination outside of enclosures in CA 176,000 dpm/100cm2

Maximum contamination outside of enclosures in clean areas (First segment move)

6,000 dpm/100cm2

Maximum contamination on segment (Segment 8) 23,811,141 dpm/100cm2

Maximum contamination pre-decon on coils 1,500,000 dpm/100cm2

Post coil decon contamination level (same coil) 40,500 dpm/100cm2

TF Upper/Lower enclosure maximum airborne concentration during cutting

48.9 / 5.75 microCuries/m3

Maximum permacon airborne concentration 8.00 microCuries/m3

Maximum general area airborne concentration (Test Cell) 0.805 microCuries/m3

Lowest general area airborne concentration (Test Cell) 4.02E-3 microCuries/m3

June 25-26, 2002 D&D Lessons Learned Workshop 19

Lessons Learned

• Because we lacked an adequate dose model for determining whole body dose due to the deposition of Tritiated particulates in the body, all personnel were required to wear air supplied respirators inside containment.

• This proved to be the correct protective measure although it did prolong the work performed inside the containments. Even with an adequate dose model we believe that workers inside containment would have exceeded our regulatory limit for skin and clothing contamination of 10,000 dpm/100cm2 if these protective measures had not been taken.

June 25-26, 2002 D&D Lessons Learned Workshop 20

• Careful job planning and proper HP contamination controls reduced the areas designated as contamination areas and reduced the spread of contamination to clean areas. Additional measures such as the vacuum vessel segment “diaper” while moving the vessel segment helped prevent the spread of contamination to clean areas and helped to protect workers from un-necessary contamination. Segment Diaper

Lessons Learned

June 25-26, 2002 D&D Lessons Learned Workshop 21

Lessons Learned

• Clean materials and equipment entering contamination areas should be better controlled. – Many small tools, equipment, and items were brought into

contamination areas when the same tools or items were already contaminated.

– Better planning on materials entering the areas should be performed.

– Seek alternatives to materials which cannot be surveyed.• Example: HP currently has no approved method for performing a

Tritium survey of the foam used during D&D.