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PHILOTECHNICS Decommissioning Radiological Laboratories in California CCRSO Conference October 5, 2007 Presented by: Jon Dillon, M.S.

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Presentation on theme: "PHILOTECHNICS Decommissioning Radiological Laboratories in California CCRSO Conference October 5, 2007 Presented by: Jon Dillon, M.S."— Presentation transcript:

1 PHILOTECHNICS Decommissioning Radiological Laboratories in California CCRSO Conference October 5, 2007 Presented by: Jon Dillon, M.S.

2 PHILOTECHNICS Decommissioning Planning Management commitment Key stakeholders Project team Establish reasonable timelines Development of RFP and project scope Early contact with CDPH

3 PHILOTECHNICS Estimated Timelines Will vary depending on scope Typical overall timeline –Prepare Decommissioning Plan (15-30 days) –Submittal and approval to CDPH (~60 days) –Perform site survey (2-30 days) –Prepare Final Status Survey Report (15 days) –Submission and approval of report by CDPH (Variable?) Terminating a facility typically takes from 3-6 months on average post FSS Make management aware early!!!

4 PHILOTECHNICS Decommissioning Planning Perform Historical Site Assessment (HSA) –Review facility license and all amendments –Employee interviews –Monthly inventory logs –Source leak test records –History of releases or spills Performing a complete HSA is critical to maintaining the timeline and terminating the license

5 PHILOTECHNICS Decommissioning Planning (cont.) Federal limit of 25 mrem/yr does not apply to CA Currently no dose based release criteria in CA Regulations specified in CCR Title 17, 30256 Case by case evaluation by CDPH Select your facility's criteria –ALARA –RAM License Conditions –Corporate Culture –Risk –Overall Timing for Decommissioning

6 PHILOTECHNICS Decommissioning Criteria Contamination levels on building surfaces –Removable –Total Criteria Specified by –NRC Regulatory Guide 1.86 –Facility RAM License Limits –NUREG-1757 –NUREG-1575 (MARSSIM )

7 PHILOTECHNICS Regulatory Guide 1.86

8 PHILOTECHNICS Facility RAM License Criteria Most conservative limits for Specific Licensees Not recommended –Increased radioactive wastes –Problematic for instrument detection limits –Usually only specifies a removable contamination limit

9 PHILOTECHNICS NUREG-1757 Consolidated NMSS Decommissioning Guidance Three volumes addressing following topics: –“Decommissioning Process for Materials Licensees” –“Characterization, Survey, and Determination of Radiological Criteria”; and –“Financial Assurance, Recordkeeping, and Timeliness”

10 PHILOTECHNICS NUREG 1757 (cont.) Volume 2 of the NUREG provides guidance on compliance with radiological criteria for license termination Many sections of 1757 will reference to MARSSIM MARSSIM does not cover DCGL determination, subsurface contamination or materials and equipment, where 1757 does provide guidance

11 PHILOTECHNICS NUREG-1575 (MARSSIM) Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) Most up to date and statistically valid method for decommissioning Recognized by NRC, DOE, DOD, and EPA Advantages –True dose based assessment –Allows higher limits of contamination –Produces less radioactive wastes –Fewer sample locations required –Based on statistical certainties

12 PHILOTECHNICS MARSSIM Process (Data Life Cycle) Plan (DQO Process) Implement (conduct surveys) –Scanning, direct measurements and sampling Assess (data quality assessment) –Statistical Tests and EMC Decide (compliance with release criteria) Evaluate (DQA)

13 PHILOTECHNICS Example MARSSIM Based Criteria Derived Concentration Guideline Levels (DCGLs) Based on a 1 mrem/yr Dose Criteria Significant difference from historic guidelines IsotopeDCGL w ’s (DPM/100 cm 2 ) Removable DCGL w ’s (DPM/100 cm 2 ) H-35.0 x 10 6 1,000 C-141.5 x 10 5 1,000 P-323.8 x 10 5 1,000 P-331.7 x 10 6 1,000 S-355.0 x 10 5 1,000 I-1252.7 x 10 4 1,000

14 PHILOTECHNICS Determination of DCGL Outside scope of MARSSIM, however NUREG 1757 (NUREG-1727) provides guidance Consider scenarios –Residential, Commercial/Industrial, Recreational, etc. Consider pathways –External, Ingestion (water, meat, soils, etc.) –Drinking water –Inhalation DandD or RESRAD

15 PHILOTECHNICS Types of DCGLs DCGL W –DCGL for residual radioactivity evenly distributed over a large area –Use with WRS or Sign test DCGL EMC –DCGL for small areas of elevated activity –Elevated measurement comparison to identify areas that require further investigation –Different assumptions that DCGL W

16 PHILOTECHNICS DQO Process 1.State the problem 2.Identify the decision 3.Identify inputs to the decision 4.Define the study boundaries 5.Develop a decision rule 6.Specify limits on decision errors 7.Optimize the survey design DQO Process is a series of planning steps for establishing criteria for data quality and developing survey designs

17 PHILOTECHNICS Example Data Quality Objectives (DQOs) Default Screening Values (DSVs) –Typically set at 20 to 50% of DCGLs Instrument Detection Limits (ideally) –Recommendation is the Static MDC is 10 – 50% of the DCGL Must be known prior to selecting survey instrumentation Dose modeling analysis Decision Errors

18 PHILOTECHNICS Instrument Selection Research isotopes require sensitive instruments capable of detecting low energy beta emitters Separate instruments must be used to detect gamma emitters like I-125 Instruments need to be calibrated at energies similar to isotopes of concern Calculate efficiencies correctly (2  vs. 4  )

19 PHILOTECHNICS Typical Instrument Specs Detector Model Detector Type Detector Area Meter Model Window Thickness Typical Total Efficiency Ludlum 43-68 Gas Flow Proportional 126 cm 2 Ludlum 2350-1 0.4 mg/cm 2 7% ( 14 C) Ludlum 43-37 Floor Monitor Gas Flow Proportional 582 cm 2 Ludlum 2350-1 0.8 mg/cm 2 6% ( 14 C) Eberline SPA-3 2” x 2” NaI 20.4 cm 2 Ludlum 2350-1 N/A 900 cpm/  R/hr ( 137 Cs) Beckman LS6000 Liquid ScintillationN/A Beckman N/A 40% ( 3 H) 80% ( 14 C)

20 PHILOTECHNICS Typical Instrument MDCs Type Detector Model Meter Model Scan Rate Count Time Bkg (cpm) MDC (dpm/100cm 2 ) Surface Scans Ludlum 43-68 Ludlum 2350-1 5 cm/sec N/A4582,594 ( 14 C) Surface Scans Ludlum 43-37 Ludlum 2350-1 5 cm/sec N/A1,480959 ( 14 C) Surface Scans Soils Eberline SPA-3 Ludlum 2350-1 0.5 m/sec NA10,000 2.03 pCi/g ( 137 Cs) Total Surface Activity Ludlum 43-68 Ludlum 2350-1 N/A1 min.4581,163 ( 14 C) Removable Activity Liquid Scintillation BeckmanN/A1 min. 8 ( 3 H) 12 ( 14 C) 41 ( 3 H) 24 ( 14 C)

21 PHILOTECHNICS Typical Instruments

22 PHILOTECHNICS MDC Comparison Large Area probe –~6% total efficiency for C-14 –Probe area 100 cm 2 –Bkg ~350 cpm, 1 min counts G-M probe –~3% total efficiency for C-14 –Probe area 19.6 cm 2 –Bkg ~50 cpm, 1 min counts NUREG-1507

23 PHILOTECHNICS MDC Comparison Large area probe –Static MDC is 1,500 dpm/100 cm 2 –Scan MDC is 3,333 dpm/100 cm 2 G-M probe –Static MDC is 6,105 dpm/100 cm 2 –Scan MDC is 18,179 dpm/100 cm 2 If you have restrictive DCGL you can see how instrument selection is critical

24 PHILOTECHNICS Historical Site Assessment (HSA) Identify potential sources of contamination Differentiate areas of different contamination potential – Impacted vs. Non-Impacted Provide input to scoping and characterization survey design Provide assessment for potential of contaminant migration Classification of Areas (Class 1, 2, 3)

25 PHILOTECHNICS Characterization Surveys Biased based on history, material use and storage Scan percentages based upon area classification Be consistent with planned FSS to potentially use as FSS data Combination of scans, static and removable measurements Removable contamination measurements obtained in areas of highest activity Identifies areas of contamination which require remediation

26 PHILOTECHNICS Final Status Surveys Demonstrate that residual radioactivity in each survey unit satisfies release criteria Builds on data from HSA and results from scoping and/or characterization surveys Goal is to be able to reject null hypothesis meaning area meets release criteria Background reference areas very important Sample size calculated that can statistically demonstrate compliance with the derived concentration guideline levels (DCGLs)

27 PHILOTECHNICS Does your lab look like this?


29 PHILOTECHNICS Example Systematic Lab Design

30 PHILOTECHNICS Typical FSS Report Contents Final Report will be prepared using the guidance of NUREG 1757 Volume 2, Section 4.5. The Final Report will include, at a minimum: An overview of the results of the FSS A summary of the screening values (if used) A discussion of any changes that were made in the FSS from what were proposed in this plan A description of the method by which the number of samples was determined for each survey unit A summary of the values used to determine the number of samples and a justification for these values A description of the data quality objectives used in the design and performance of the Final Status Survey

31 PHILOTECHNICS Typical FSS Report Contents (cont.) The survey results for each survey unit including the following: The number of samples taken for the survey unit; –A description of the survey unit, including (a) a map or drawing showing the reference system and random start systematic sample locations for Class 1 and Class 2 survey units and reference area, as applicable, and the random locations shown for Class 3 survey units and reference areas; (b) discussion of remedial actions and unique features; and (c) areas scanned for Class 3 survey units and reference areas –The measured sample concentrations in units comparable to the screening values –The statistical evaluation of the measured concentrations

32 PHILOTECHNICS Typical FSS Report Contents (cont.) –Judgmental and miscellaneous sample data sets reported separately from those samples collected for performing the statistical calculations –A discussion of anomalous data, including any areas of elevated activity detected during scan surveys that exceeded the investigation levels or any measurement locations in excess of the screening values –A statement that a given survey unit satisfies the screening values and the elevated measurement comparison if any sample points exceeded the screening values A description of any changes in initial survey unit assumptions relative to the extent of residual activity (e.g., material not accounted for during site characterization) A description of how As Low As Reasonably Achievable practices were employed to achieve final activity levels. A final RESRAD or D&D run confirming dose

33 PHILOTECHNICS FSS Key Considerations Accurate HSA & consider decay when appropriate Static MDC should be <50% of DCGL Scan MDC comparison to DCGL for determination of additional measurements Proper classification of areas Planning to minimize duplication Equipment (Free Release) Keep systems separate (e.g. vacuum, drain, ventilation) Licensing

34 PHILOTECHNICS FSS Potential Pitfalls Poor instrument selection Release limits not clearly defined Scope of work not clearly defined Selecting a DCGL that is too restrictive MDCs of Instruments (Static, Scan) Gross DCGL Incorrect number of samples Not addressing systems

35 PHILOTECHNICS Summary Plan early & commit resources Negotiations with CDPH Internal staff vs. external support FSS Report is key element for release Time spent in planning and managing can reduce overall timeline Documentation, documentation, documenation Success will be measured more by meeting deadlines than meeting release limits


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