1 / 35

VSP: A Primary Planning Tool for Independent Characterization and Verification

VSP: A Primary Planning Tool for Independent Characterization and Verification. Timothy J. Vitkus , CHP Associate Director, IEAV THE ASP 2013 Annual Workshop September 25, 2013. Historical Time Savings.

nico
Download Presentation

VSP: A Primary Planning Tool for Independent Characterization and Verification

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. VSP: A Primary Planning Tool for Independent Characterization and Verification Timothy J. Vitkus, CHP Associate Director, IEAV THE ASP 2013 Annual Workshop September 25, 2013

  2. Historical Time Savings • Level of effort for planning and plotting sample plans required multiple tools and hours of time not too long ago • Integrates very well with: • Arc/GIS and similar geo-referenced systems • Google maps evenfor pre-GIS expertise and software/hardware tools • Visio • AutoCAD

  3. Benefits and Time Savings for Challenging Project • Fukushima airborne releases impacted U.S. maritime assets involved in Operation TOMODACHI • Conducted characterization and now designing and implementing radiological release surveys • Multi-deck, complex, inter-related air handling systems and compartments requiring FSS plans • Basis for a proposed procedure for hard-to-detect radionuclides in soil

  4. Shaded areas: air handling via collective protection system; exempt from release surveys

  5. Independent Characterization Applications • Waste characterization and sanitary and EMWMF waste acceptance criteria determinations: • 34-Building ARRA demolition project • K-33 demolition project • Isotope Row • Random distribution of intrusive sample locations: • Waste lots spanned multiple buildings and structural populations (walls vs. floors vs. roofs, etc.) • Characterization mean estimation and Th-232 surface/subsurface correlation determination evaluations

  6. EMWMF Characterization

  7. Sanitary Waste Planning RSS selected to provide quantitative data demonstrating compliance with 5400.5 release guidelines and to select locations for intrusive samples for TSCA/RCRA considerations

  8. FSS and Independent Verification Surveys • K-25 process gas piping (PGP) U-235 hold-up measurement verification: • Contractor required to determine U-235 hold-up/foot PGP (criticality determinations) and average/foot for disposal WAC • VSP RSS module used for verification of mean

  9. FSS and Independent Verification Surveys (cont.) • VSP RSS module used extensively for verification soil survey units undergoing MARSSIM-based release process: • MARSSIM FSS based on hypothesis test of the mean/median concentration to release limit • Verification not intended to “reproduce” a MARSSIM release survey • Evaluate the site conclusion as to the mean site concentration and also determine if hot spots are present

  10. Procedure Proposed to MARSSIM Work Group for Addressing Hard-to-DetectRadionuclides in Soil • Procedure statistical basis: Ranked Set Sampling (EPA QA/G-5S, Guidance on Choosing a Sampling Design for Environmental Data Collection; December 2002). • Procedure implementation basis: Visual Sample Plan RSS module (Pacific Northwest National Laboratory: http://vsp.pnnl.gov/) together with: • Arc/GIS software for mapping and random-start/systematic placement.

  11. Procedure Bases (cont.) • Balances HTD hot spot detection probability with analytical cost • MARSSIM non-parametric statistical basis maintained • RSS used to differentiate relative concentrations of HTD alpha, beta, low-energy/abundance gamma emitters in soil • Concept presented at 2011 HPS Topical Mid-Year and full procedure presented at the 2013 HPS Annual Meeting • MARSSIM Work Group: Procedure is under evaluation for inclusion as Appendix E in MARSSIM revision • The following is abbreviated version of 2013 HPS presentation

  12. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application • Example Inputs/Assumptions: • HTDs: Empirical study RSS ranking ability for alpha-emitters and beta-emitters with βmax energy >250 keV (e.g. Tc-99, Sr-90) • VSP input parameters (True Average vs. Fixed Threshold module, i.e. MARSSIM Sign Test): • Survey unit mean and standard deviation • DCGL • Decision errors • Probability (p) of identifying a hot spot of a given size • Minimum ranking capability (MRC): α = 5 to 10 pCi/g; 250 keVβ = 100 to 200 pCi/g • MRC limitation is used for comparison to the applicable DCGLEMC • Following example uses Tc-99

  13. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application

  14. VSP inputs and required number of FSS samples to satisfy DQOs. N = 15

  15. Samples locations are distributed in the survey unit. The largest unsampled area = 133 m2

  16. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application (cont.) • Determine hot spot size of concern: • For example: 74 Class 1 characterization samples used to determine a pre-site remediation 95% and 99% upper confidence levels (UCL) of 787.9 and 955.4 pCi/g, respectively • Compared with the maximum concentration identified during characterization • Of the 74 characterization samples, two exceeded the 99% UCL from a historical spill area

  17. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application (cont.) • Proposed the 99% UCL concentration value to determine associated maximum hot spot size of concern from area factor table: • DCGLEMC = 955.4 pCi/g • NOTE: The above is just one possible approach, other options are available and should be discussed with the regulatory authority. • MRC = 100 to 200 pCi/g • Actual MRC < Required MRC • Area Factor of 48.7 = 17.4 m2 • 2000 m2/17.4 m2 results in N = 115 samples to satisfy DCGLEMC requirements

  18. The initial plan N = 15 forms the basis for the RSS 133 m2 sub-grids. • NEMC = 115 • s the basis for the RSS 133 m2sub-grids. • NEMC = 115

  19. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application (cont.) • Therefore, N = 115 is adjusted to allow for appropriate RSS set size (typically 3 ranking locations per set) and 1 complete cycle (within each subunit. One complete cycle requires 9 locations (set size2) • Results in N = 135 = 9 RSS locations within each of the 15 subunits • The 135 locations are distributed in the survey unit • Currently VSP will only distribute randomly; random-start/systematic is not an option.

  20. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application (cont.) • Use “Predetermined Number of Samples” module which includes random-start systematic option

  21. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application (cont.) • Finally, randomize the 9 locations within each sub-unit based on Cycle-Set-Location 1, 2, or 3 • In the following figure, Arc/GIS was used

  22. RSS sample plan across subunits

  23. HTD Procedure* Performed *(HPS 2013 for full procedure)

  24. MARSSIM/RSS Integrated FSS Planning Procedure: Example Application (cont.) • 45 samples are collected for laboratory analysis, (60% reduction) + any judgmental • Sign test performed on results

  25. MARSSIM/RSS Integrated FSS Planning Procedure: Hot Spot Detection Probability • VSP may then be used to estimate the probability of detecting hot spots smaller than those in the design plan. How small do we have to go? • Design basis probability of 0.9998 for RSS sampling of 18.3 m2elliptical hot spot. Equates to a risk of 0.0002 (1-p). • The probability of detecting smaller hot spots: • The probability for detection of a 10 m2 elliptical hot spot for example survey design decreases to 0.6792, and so on. • Final check with stakeholders

  26. Recommendations for VSP Enhancement • Incorporate COMPASS • Update and maintenance of COMPASS has not been funded since Vista OS • Very complementary software, some redundancies in capabilities related to MARSSIM FSS planning; unique features include: • DCGL modification, ties in hot spot and scan MDC requirements, power curves, and others • ORAU has received authorization from funding agency to transfer source code to PNNL • Recent MARSSIM Work Group communication citing COMPASS for Power Curves

  27. Other COMPASS Attributes: • Modified/Gross DCGL • Scan MDC Class 1 Requirements • Auto Unity Rule Applications • Others

  28. Correspondence from MARSSIM Work Group Committee member: A follow-up to our phone call to complete my action item in the meeting minutes regarding a freeware to generate Power Curves… The COMPASS Freeware generates the power curves

  29. Recommendations for Modifications • Random-start/systematic option for RSS locations (expect the HTD procedure to be in the forthcoming MARSSIM revision) • An app for that? • Better “undo” functionality • .txt to Excel formatting improvements (primarily headers) • Prospective and retrospective power curves, (these are similar to the current Decision Performance Goal Diagrams in VSP) • Other COMPASS functionalities that enhance VSP

More Related