Characterization Surveys and Early Site Investigations. Tom Hansen, CHP, PMP Ameriphysics, LLC

Transcription

1 Characterization Surveys and Early Site Investigations Tom Hansen, CHP, PMP Ameriphysics, LLC

2 Outline Introduction to Characterization Overview of the RSSI Process Historical Site Assessment Radiological Surveys Other Considerations Summary References copyright Ameriphysics, LLC

3 Introduction to Characterization Characterization can be viewed as the initial steps toward site decommissioning It is an iterative process, and is used to: Define the scope of work and prepare site plans Select decontamination and decommissioning techniques Develop waste disposal strategies Refine cost estimates and schedules Collect data needed for regulatory or stakeholder approval Develop ES&H controls Determine release criteria, and Provide input for Final Status Survey design copyright Ameriphysics, LLC

4 Introduction to Characterization Inputs The primary types of activities performed during characterization consist of records and documentation reviews, surveys and sampling, and data analysis and dose modeling The following graph shows an example of the level of each of these activities during a decommissioning project not actual data, rather graph to show focus of effort over project copyright Ameriphysics, LLC

5 Introduction to Characterization Analysis Surveys Records Records Surveys Analysis Records Surveys Analysis copyright Ameriphysics, LLC

6 Introduction to Characterization Outputs The type and extent of radiological and non-rad contaminants The level of surface and volumetric contamination Site-specific pathways and any off-site contaminants Background reference areas (if needed) Recommendations regarding instrumentation, analytical methods, and data analysis protocols The data necessary to conduct further project planning Input for final status/release surveys copyright Ameriphysics, LLC

7 Introduction to Characterization Regulator and Stakeholder Interaction Since characterization provides information to support license termination both regulators and stakeholders are often keenly interested in the planning and conduct of characterization These interests often manifest themselves as regulatory and stakeholder approvals of the characterization plan The characterization planning process should be developed in a manner to support outside reviews copyright Ameriphysics, LLC

8 Overview of the RSSI Process Radiation Survey and Site Investigation (RSSI) Process A consensus approach, agreed upon by DOE, DOD, EPA, and NRC, to demonstrate compliance with a dose or risk-based regulation A graded approach that starts with the Historical Site Assessment (HSA) and is later followed by other surveys that lead to the final status survey Each survey has specified goals and objectives to support a final decision on whether or not a site or facility complies with the appropriate regulations copyright Ameriphysics, LLC

9 Overview of the RSSI Process Steps of the RSSI Process Site Identification Historical Site Assessment Scoping Survey Characterization Survey Remedial Action Support Survey Final Status Survey Confirmation and Verification copyright Ameriphysics, LLC

10 Historical Site Assessment The primary purpose of the Historical Site Assessment (HSA) is to collect existing information concerning the site and its surroundings Areas that have no reasonable potential for residual contamination are classified as non-impacted areas Areas with some potential for residual contamination are classified as impacted areas copyright Ameriphysics, LLC

11 Historical Site Assessment The primary objectives of the HSA are to: Identify potential sources of contamination Determine whether or not the site poses a threat to human health and the environment Differentiate impacted from non-impacted areas Provide input to scoping and characterization survey design Provide an assessment of the likelihood of contaminant migration, and Identify additional potential radiation sites copyright Ameriphysics, LLC

12 Historical Site Assessment The HSA typically consists of three phases: Identification of a candidate site Preliminary investigation of the facility or site Site visits or inspections copyright Ameriphysics, LLC

13 Historical Site Assessment Data Sources Design and as built drawings Facility modifications Licenses, applications, and correspondence Routine surveys Other operating records and documents Interviews with operators and support personnel Event log - accidents and unplanned events Photographs Construction materials copyright Ameriphysics, LLC

14 Historical Site Assessment The HSA is followed by an evaluation of the site based on the information collected Identify potential contaminants Identify potentially contaminated areas Identify potentially contaminated media Develop a conceptual model of the site Professional judgment copyright Ameriphysics, LLC

15 Historical Site Assessment Identify Potential Contaminants How long was the site operational? What types of processes occurred at the site? What is the probability of leakage from the sources? Where are the most likely locations for contamination within the facility? copyright Ameriphysics, LLC

16 Historical Site Assessment Identify Potentially Contaminated Areas Initial assessment should allow areas to be classified as impacted or non-impacted Impacted areas have a reasonable potential for contamination based on historical data or known contamination Material storage and usage locations; spill, leak, and discharge areas; onsite disposal or burial locations Non-impacted areas have no reasonable potential for residual contamination May be based on site history, previous investigations, or activity within that portion of the site (i.e. offices vs. processing area) copyright Ameriphysics, LLC

17 Historical Site Assessment Identify Potentially Contaminated Areas All sources of contamination in impacted areas should be identified and their dimensions recorded (vertically and horizontally if possible) Sources can be delineated and characterized through: Visual inspection (during reconnaissance visit) Interviews with knowledgeable personnel associated with the site Waste disposal, waste manifests, and waste sampling data Potential for migration of contamination (off-site and onsite) should be evaluated where appropriate copyright Ameriphysics, LLC

18 Historical Site Assessment Identify Potentially Contaminated Media Once the potential sources and locations of contamination have been identified, one must look at the type of environmental media that has been impacted These media include: Surface and subsurface soils Surface water and ground water Air Buildings / physical structures copyright Ameriphysics, LLC

19 Historical Site Assessment Develop a Conceptual Model A site diagram showing : General layout of the site Building locations Site boundaries Areas of known contamination Areas of suspected contamination Types and concentrations of contaminants in impacted areas Potentially contaminated media, and Locations of background (non-impacted) areas copyright Ameriphysics, LLC

20 Historical Site Assessment Develop a Conceptual Model The conceptual model is used to : Assess nature and extent of contamination Identify potential contaminant sources Identify release mechanisms Identify potential exposure pathways Identify human or ecological receptors Identify data gaps, and Provide organized approach to assessing the need for and collecting additional site characterization data copyright Ameriphysics, LLC

21 Historical Site Assessment Develop a Conceptual Model The HSA is the initial step in the development of this model The conceptual model should be upgraded and modified as the site characterization data become available copyright Ameriphysics, LLC

22 Historical Site Assessment Professional Judgment Professional judgment is the expression of opinion based on technical knowledge and professional experience, assumptions, algorithms, and definitions There may be circumstances where traditional sources of information, data, models, or scientific principles are unavailable, unreliable, conflicting, or too costly or time consuming to obtain Professional judgment can be used as an independent review of historical data to support decision making in situations where data are not reasonably obtainable by collection or experimentation copyright Ameriphysics, LLC

23 Historical Site Assessment Historical Site Assessment Report A document that summarizes what is known about the site, what is assumed or inferred, activities conducted during the HSA, and all researched information References should be cited for each factual statement The report should be organized in such a way that it supports the site conceptual model It may be advisable to have an independent review of the report for factual accuracy copyright Ameriphysics, LLC

24 Radiological Surveys Types Scoping Characterization Remedial Action Support copyright Ameriphysics, LLC

25 Radiological Surveys Scoping Survey The primary objectives of a scoping survey are to: Perform a preliminary hazard assessment Support classification of all or part of the site as a Class 3 area Evaluate whether the survey plan can be optimized for use in the characterization or final status surveys Provide input to the characterization survey design if necessary copyright Ameriphysics, LLC

26 Radiological Surveys Scoping Survey Scoping surveys are conducted after the HSA is completed and consist of judgment measurements based on the HSA data If the results of the HSA indicate that an area is impacted and no contamination is found, the area may be classified as Class 3 and a Class 3 final status survey is performed If the scoping survey locates contamination, the area may be considered Class 1 or 2 for the final status survey and a characterization survey is typically performed copyright Ameriphysics, LLC

27 Radiological Surveys Characterization Survey If an area could be classified as Class 1 or Class 2 for the final status survey, based on the HSA and scoping survey results, a characterization survey is warranted The characterization survey is planned based on the HSA and scoping survey results This type of survey is a detailed radiological investigation of the area copyright Ameriphysics, LLC

28 Radiological Surveys Characterization Survey The primary objectives of a characterization survey are to: Determine the nature and extent of the contamination Collect data to support evaluation of remedial alternatives and technologies Evaluate whether the survey plan can be optimized for use in the final status survey Support Remedial Investigation/Feasibility Study requirements Provide input to the final status survey design copyright Ameriphysics, LLC

29 Radiological Surveys Characterization Survey The characterization survey is the most comprehensive of all the survey types and generates the most data This includes preparing a reference grid, systematic as well as judgment measurements, and surveys of different media (e.g., surface soils, interior and exterior surfaces of buildings) The decision as to which media will be surveyed is a site-specific decision addressed throughout the Radiation Survey and Site Investigation Process copyright Ameriphysics, LLC

30 Radiological Surveys Remedial Action Support Survey If an area is adequately characterized and is contaminated above the release criterion, a decontamination plan should be prepared A remedial action support survey is performed while remediation is being conducted and guides the cleanup in a real-time mode copyright Ameriphysics, LLC

31 Radiological Surveys Remedial Action Support Survey Remedial action support surveys are conducted to: Support remediation activities Determine when a site or survey unit is ready for the final status survey Provide updated estimates of site-specific parameters used for planning the final status survey copyright Ameriphysics, LLC

32 Radiological Surveys Remedial Action Support Survey The determination that a survey unit is ready for a final status survey following remediation is an important step in the RSSI Process Remedial activities result in changes to the distribution of contamination within the survey unit, and site-specific parameters used during final status survey planning may need to be reestablished following remediation Obtaining updated values for these critical parameters should be considered when planning a remedial action support survey copyright Ameriphysics, LLC

33 Radiological Surveys Preliminary Considerations Selection of survey instrumentation and analytical techniques are typically based on a knowledge of the appropriate DCGLs, because remediation decisions are made based on the level of the residual contamination as compared to the DCGL Exposure rate measurements may be needed to assess occupational and public health and safety The location of underground utilities should be considered before conducting a survey to avoid compounding the problems at the site copyright Ameriphysics, LLC

34 Radiological Surveys Preliminary Considerations Adequacy of Historical Site Assessment Designed to confirm HSA conclusions Scaling factors Release potentially non-impacted areas Use of GPS Serves as a guide for the final or release survey Adequate for Job Safety Analysis Regulatory agency may request outputs (reports) copyright Ameriphysics, LLC

35 Radiological Surveys Survey Planning Types of samples and measurements (systematic, random, biased) Required sensitivity of instruments Number of samples and measurements Sample and measurement location Types of analyses Data validation and QC/QA Data reporting copyright Ameriphysics, LLC

36 Radiological Surveys Instrument Selection Radiation type and energy Minimum Detectable Activity (or Concentration) Instrument measurement efficiency Scaler or rate meter Qualitative vs. quantitative data New technologies copyright Ameriphysics, LLC

37 Radiological Surveys copyright Ameriphysics, LLC

38 Radiological Surveys copyright Ameriphysics, LLC

39 Radiological Surveys copyright Ameriphysics, LLC

40 Radiological Surveys Low background alpha-beta counters Gamma spectroscopy copyright Ameriphysics, LLC

41 Radiological Surveys copyright Ameriphysics, LLC

42 Radiological Surveys copyright Ameriphysics, LLC

43 Radiological Surveys Positioning Systems Allows exact location to be recorded properly each time a sample is taken Use of traditional map- spotting techniques are slow and require trained personnel Modern positioning techniques: global positioning system (GPS) and microwaves, ultrasound and laser ranging systems are preferable copyright Ameriphysics, LLC

44 Radiological Surveys copyright Ameriphysics, LLC

45 Radiological Surveys GammaCam TM Both a two- and a three dimensional GammaCam system have been developed Provides remote 2D or 3D information on position and relative strengths of gamma-ray radiation fields Remote operation minimizes worker exposure, and Provides easy to read 2D or 3D color images of gamma radiation fields over black and white image copyright Ameriphysics, LLC

46 Radiological Surveys In Situ Object Counting System (ISOCS) Field deployable gamma spectroscopy Real-time in situ, non-intrusive characterization Broad energy range Monte Carlo modeling in place of conventional source calibrations Ability to model complex geometries Reduced worker exposure, and 70% cost savings compared to getting a coring sample followed by offsite analysis copyright Ameriphysics, LLC

47 Radiological Surveys Pipe Explorer TM System Pneumatically operated air-tight tubular membrane Can tow a variety of radiation detectors and video cameras Able to navigate around elbows and obstructions Contamination doesn t move with detectors, eliminating false readings, and More cost effective than demolition on large jobs copyright Ameriphysics, LLC

48 Radiological Surveys Surveillance and Measurement System (SAMS) Isotopic identification in handheld detector Provides real-time data Easy to operate Can detect up to 70 (expandable to 95) radionuclides Reduces worker exposure, and Capital cost of $10,000 is recovered after 66 samples have been analyzed copyright Ameriphysics, LLC

49 Radiological Surveys Surface Contamination Monitor 400 radiation measurements per square meter About 70% cost reduction compared to surveys with handheld instruments 5-6 times faster for beta-gamma and 2 times faster for alpha survey, and 16 times faster for free release surveys due to automated report generation copyright Ameriphysics, LLC

50 Radiological Surveys Characterization Survey Reporting Site characterization and operational history Instrumentation and survey procedures Findings and results Clearly identify contaminant levels and impacted areas Data presentation Maps and figures Supporting information and QA/QC Documentation developed to support regulator and stakeholder review for license release copyright Ameriphysics, LLC

51 Other Considerations Chemical processes identified from HSA Typical ACM, PCB, lead-paint and mold Based on construction materials and time period of construction ES&H for sampling activities proper PPE Mindful of disposal site requirements for materials copyright Ameriphysics, LLC

52 Other Considerations XRF Analysis Hand-held battery-operated unit Can analyze 25 elements Stores up to 3,000 data points Results available in 20 seconds 96% cost savings compared to sample and analysis by laboratory, and Capital cost of $25,000 is recovered after only 20 samples copyright Ameriphysics, LLC

53 Summary Successful characterization requires investigation and planning Ensure that all potential areas of contamination (all media and pathways) are investigated Select the proper tools and methods for the investigation Review and revise as needed based on results copyright Ameriphysics, LLC

54 References EPA 1994 Guidance for the Data Quality Objectives Process DOE 1994 Decommissioning Handbook IAEA 1997 Radiological Characterization of Shutdown Nuclear Reactors for Decommissioning Purposes IAEA TRS #389 NRC 2000 MARSSIM (NUREG-1575, Rev 1) ASME 2004 Decommissioning Handbook copyright Ameriphysics, LLC

55 Characterization Surveys and Early Site Investigations Tom Hansen, CHP, PMP Ameriphysics, LLC