ML070160544

Yankee Nuclear Power Station Final Status Survey Report, YNPS-FSS-SVC-01-00

ML070160544
Person / Time
Site:	Yankee Rowe
Issue date:	09/21/2006
From:	Jeffery Lynch Yankee Atomic Electric Co
To:	Document Control Desk, NRC/FSME
References
BYR 2006-083 YNPS-FSS-SVC-01-00
Download: ML070160544 (91)

Text

YANKEE ATOMIC ELECTRIC COMPANY Telephone (413) 4245261 49 Yankee Road, Rowe, Massachusetts 01367 YA N K EEý September 21, 2006 BYR 2006-083 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-001

References:

(a) License No. DPR-3 (Docket No. 50-29)

(b) BYR 2004-133, Submittal of Revision 1 to the Yankee Nuclear Power Station's License Termination Plan (c) Yankee Nuclear Power Station - Issuance of Amendment 158 Re: License Termination Plan

Subject:

Submittal of YNPS-FSS-SVCO1-00, the Final Status Survey Report for Survey Area SVC-01

Dear Madam/Sir:

This letter submits YNPS-FSS-SVCO1-00, Final Status Survey Report for SVC-01. This report was written in accordance with Section 5 of the YNPS License Termination Plan, "Final Status Survey Plan," and is consistent with the guidance provided in the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM).

We trust that this information is satisfactory; however if you should have any questions or require any additional information, please contact Alice Carson at (301) 916-3995.

Sincerely, YANKEE ATOMIC ELECTRIC COMPANY for Joseph R-Lynch Regulatory Affairs Manager

Enclosure:

YNPS-FSS-SVCO1-00 (2 hard copies plus CD)

U.S. Nuclear Regulatory Commission BYR 2006-083, Page 2 cc (w/o encl):

cc (w/encl on CD)

S. Collins, NRC Region I Administrator Marie Miller, Chiet Decommissioning Branch, NRC Region I L. Kauffman, Region I J. Kottan, Region I D. Everhart, Region I J. Hickman, NRC Project Manager E. Waterman, US Environmental Protection Agency, Region 1 R. Walker, Director, MA DPH W. Perlman, Executive Committee Chair, FRCOG T.W. Hutcheson, Chair, Franklin Regional Planning Board L. Dunlavy, Executive Director, FRCOG P. Sloan, Directory of Planning & Development, FRCOG D. Howland, Regional Engineer, MA DEP M. Whalen, MA DPH D. Katz, CAN Jonathan Block, CAN

Yankee Nuclear Plant Station Final Status Survey Report For SVC-01 Yankee Atomic Electric Company

YANKEE NUCLEAR POWER STATION FINAL STATUS SURVEY REPORT REPORT NO.: YNPS-FSS-SVC-01-00 Prepared by:

Reviewed by:

Approved by:

Michael D. Reqnhack, FSS Radiological Engineer Rot-bertM'o

'ýg adiological Engineer Date:j - / a-6r6 Date: 211j0*

Date:

3 MIartiikknEckso(,'SS Manager

Report No.: YNPS-FSS-SVC-O1-O0 Section Table of Contents Page 1.0 EX EC U T IV E SU M M A R Y...........................................................................................................................

I 1.1 IDENTIFICATION OF SURVEY A REA AND U NIT..........................................................................................

1 1.2 D ATES(S) OF SURVEY.................................................................................................................................

1 1.3 N UM BER AND T YPES OF M EASUREM ENTS C OLLECTED........................................................................... 1 1.4 SUM M ARY OF SURVEY R ESULTS...............................................................................................................

2 1.5 C ONCLUSIONS............................................................................................................................................

2 2.0 FSS PR O G R A M O V E R V IEW....................................................................................................................

2 2.1 SURVEY PLANNING...................................................................................................................................

2 2.2 SURVEY D ESIGN.........................................................................................................................................

2 2.3 SURVEY IM PLEM ENTATION.......................................................................................................................

3 2.4 SURVEY D ATA A SSESSM ENT......................................................................................................................

3 2.5 QUALITY ASSURANCE AND QUALITY CONTROL MEASURES.............................................................. 3 3.0 SURVEY AREA INFORMATION......................................................................................................

3 3.1 SURVEY A REA D ESCRIPTION.....................................................................................................................

3 3.2 H ISTORY OF SURVEY A REA.......................................................................................................................

4 3.3 D IVISION OF SURVEY A REA INTO SURVEY U NIT...................................................................................... 4 4.0 SU RV EY U N IT IN FO R M A T IO N...............................................................................................................

4 4.1

SUMMARY

OF RADIOLOGICAL DATA SINCE HISTORICAL SITE ASSESSMENT (HSA)........................ 4 4.1.1 Chronology and D escription of Surveys Since H SA.......................................................................

4 4.1.2 R adionuclide Selection and Basis.................................................................................................

4 4.1.3 Scoping & Characterization.................................................................................................................

4 4.2 BASIS FOR C LASSIFICATION......................................................................................................................

5 4.3 REMEDIAL ACTIONS AND FURTHER INVESTIGATIONS........................................................................

5 4.4 U NIQUE FEATURES OF SURVEY U NIT................................................................................................

5 4.5 A LA RA PRACTICES AND EVALUATIONS.............................................................................................

5 5.0 SURVEY UNIT FINAL STATUS SURVEY.........................................................................................

5 5.1 SURVEY PLANNING....................................................................................................................................

5 5.1.1 Final Status Survey Plan and A ssociated D Q O s............................................................................

6 5.1.2 D eviations from the FSS Plan as W ritten in the L TP....................................................................

6 5.1.3 D C G L Selection and Use......................................................................................................................

7 5.1.4 M easurem ents.......................................................................................................................................

7 5.2 SURVEY IM PLEM ENTATION A CTIVITIES...............................................................................................

8 5.3 SURVEILLANCE SURVEYS..........................................................................................................................

8 5.3.1 Periodic Surveillance Surveys.....................................................................................................

8 5.3.2 R esurveys...............................................................................................................................................

8 5.3.3 Investigations........................................................................................................................................

8 5.4 SURVEY R ESULTS.......................................................................................................................................

9 5.5 D ATA Q UALITY A SSESSM ENT....................................................................................................................

9 6.0 QUALITY ASSURANCE AND QUALITY CONTROL....................................................................

10 6.1 INSTRUM ENT Q C C HECKS.......................................................................................................................

10 6.2 SPLIT SAM PLES AND R ECOUNTS.............................................................................................................

10 6.3 SELF-A SSESSM ENTS.................................................................................................................................

10 7.0 C O N C LU SIO N............................................................................................................................................

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Report No.: YNPS-FSS-SVC-01-00 Table List of Tables Page T A BLE I D A TE O F S U RV EY S...........................................................................................................................................

I TABLE 2 SURVEY AREA SVC-0 I DESIGN PARAMETERS............................................................................................

6 TABLE 3 DCGLw, DCGLEMC AND INVESTIGATION LEVEL FOR ISOCS MEASUREMENTS....... ERROR! BOOKMARK NOT DEFINED.

TABLE 4 FSS ACTIVITY

SUMMARY

FOR SVC-0 I SURVEY UNIT...............................................................................

8 TABLE 5 D IRECT M EASUREM ENT SUM MARY.................................................................................................................

9 TABLE 6 ISOCS SCAN

SUMMARY

.......................................................................... ERROR! BOOKMARK NOT DEFINED.

List of Appendices Appendix A - YNPS-FSSP-SVC-01, "Final Status Survey Planning Worksheets Appendix B - YA-REPT-00-0 15-04, "Instrument Efficiency Determination for Use in Minimum Detectable Concentration Calculations in Support of the Final Status Survey at Yankee Rowe" Appendix C - ALARA Evaluations, SVC-01 Appendix D -YA-REPT-00-018-05, "Use of ln-situ Gamma Spectrum Analysis to Perform Elevated Measurement Comparison in Support of Final Status Surveys" List of Attachments Attachment A - Maps and Posting Plots Attachment B - Data Quality Assessment Plots and Curves Attachment C - Instrument QC Records (In the electronic version, every Table of Contents, Figures, Appendices and Attachments, as well as every mention of a Figure, Appendix or Attachment is a hyperlink to the actual location or document.)

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Report No.: YNPS-FSS-SVC-01-00 List of Abbreviations and Acronyms AL ALARA c/dc/d DCGL DCGLEMC............

DCGLw......

DQO EMC ETD FSS FSSP GPS HoA HSA.................

HSA.................

HTD ISOCS LBGR LTP MARSSIM MDA MDC PAB QAPP........

QC.....................

RCA RP RSS SFP VC VCC VSP YNPS Action Level As Low As Reasonably Achievable Counts per Disintegration Derived Concentration Guideline Level DCGL for small areas of elevated activity DCGL for average concentration over a wide area, used with statistical tests Data Quality Objectives Elevated Measurement Comparison Easy-to-Detect Final Status Survey Final Status Survey Plan Global Positioning System Null Hypothesis Historical Site Assessment Hard-to-Detect In-situ Object Counting System Lower Bound of the Grey Region License Termination Plan Multi-Agency Radiation Survey and Site Investigation Manual Minimum Detectable Activity Minimum Detectable Concentration Primary Auxiliary Building Quality Assurance Project Plan Quality Control Radiological Controlled Area Radiation Protection Reactor Support Structure Spent Fuel Pool Vapor Container Vertical Concrete Cask Visual Sample Plan Yankee Nuclear Power Station iii

Report No.: YNPS-FSS-SVC-01-00 1.0 EXECUTIVE

SUMMARY

A Final Status Survey (FSS) was performed of Survey Area SVC-01 in accordance with Yankee Nuclear Power Station's (YNPS) License Termination Plan (LTP). This FSS was conducted as a structure surface FSS with building occupancy Derived Concentration Guideline Levels (DCGLs) even though the SVC-01 structure will be subsurface at license termination.

This practice conservatively implements LTP criteria that subsurface structure surfaces be evaluated for the presence of contamination.

1.1 Identification of Survey Area and Unit SVC-01 is comprised of the service building foundation that was exposed during excavation campaigns to remove radiologically contaminated soil and PCB-contaminated soil from the "alley way", Survey Unit NOL-01-04. Survey Unit SVC-01-18 serves as the north boundary for Survey Unit NOL-01-04. It is approximately 512 ft2 (48m2) of concrete surface area. SVC-01-18 is a portion of the Service Building foundation that remained after demolition of the service building. It is the sole surviving SVC Survey Unit, the remainder was demolished and disposed of as non-radioactive, PCB waste.

1.2 Dates(s) of Survey Table I Date of Surveys Survey Start Survey End DQA Survey Unit Date Date Date SVC-01-18 11/17/2005 12/01/2005 9/06/2006 1.3 Number and Types of Measurements Collected Final Status Survey Plan (FSSP) was developed for this Survey Unit in accordance with YNPS LTP and FSS procedures using the MARSSIM protocol. The planning and design of the survey plan employed the Data Quality Objective (DQO) process, ensuring that the type, quantity and quality of data gathered was appropriate for the decision making process and that the resultant decisions were technically sound and defensible. A total of 25 systematic direct measurement measurements were taken in the Survey Unit, providing data for the non-parametric testing of the Survey Area. In addition to the direct measurement samples, hand-held survey instrument scans were performed to provide 100 percent coverage of the Survey Area.

I

Report No.: YNPS-FSS-SVC-01-00 1.4 Summary of Survey Results Following the survey, the data were reviewed against the survey design to confirm completeness and consistency, to verify that the results were valid, to ensure that the survey plan objectives were met and to verify Survey Unit classification.

Direct measurement surveys indicated that none of the systematic measurements exceeded the DCGLw, depicted in Attachment B. Retrospective power curves were generated and demonstrated that an adequate number of samples were collected to support the Data Quality Objectives. Therefore, the null hypothesis (Ho) (that the Survey Unit exceeds the release criteria) is rejected.

1.5 Conclusions Based upon the evaluation of the data acquired for the FSS, SVC-01 meets the release requirements set forth in the YNPS LTP.

The Total Effective Dose Equivalent (TEDE) to the average member of the critical group does not exceed 25 mRem/yr, including that from groundwater.

IOCFR20 Subpart E ALARA requirements have been met as well as the site release criteria for the administrative level DCGLs that ensure that the Massachusetts Department of Public Health's 10 mRem/yr limit will also be met.

2.0 FSS PROGRAM OVERVIEW 2.1 Survey Planning The YNPS FSS Program employs a strategic planning approach for conducting final status surveys with the ultimate objective to demonstrate compliance with the DCGLs, in accordance with the YNPS LTP. The DQO process is used as a planning technique to ensure that the type, quantity, and quality of data gathered is appropriate for the decision-making process and that the resultant decisions are technically sound and defensible. Other key planning measures are the review of historical data for the Survey Unit and the use of peer review for plan development.

2.2 Survey Design In designing the FSS, the questions to be answered are: "Does the residual radioactivity, if present in the Survey Unit, exceed the LTP release criteria?" and "Is the potential dose from this radioactivity ALARA?"

In order to answer these questions, the radionuclides present in the Survey Unit must be identified, and the Survey Unit classified. Survey Unit are classified with respect to the potential for contamination:

the greater the potential for contamination, the more stringent the classification and the more rigorous the survey.

The survey design additionally includes the number, type and locations of direct measurements/samples (as well as any judgmental assessments required), scanning 2

Report No.: YNPS-FSS-SVC-01-00 requirements, and instrumentation selection with the required sensitivities or detection levels. DCGLs are developed relative to the surface/material of the Survey Unit and are used to determine the minimum sensitivity required for the survey.

Determining the acceptable decision error rates, the lower bound of the gray region (LBGR), statistical test selection and the calculation of the standard deviation and relative shift allows for the development of a prospective power curve plotting the probability of the Survey Unit passing FSS.

2.3 Survey Implementation Once the planning and development has been completed, the implementation phase of the FSS program begins.

Upon completion of remediation and final characterization activities, a final walk down of the Survey Unit is performed. If the unit is determined to be acceptable (i.e. physical condition of the unit is suitable for FSS), it is turned over to the FSS team, and FSS isolation and control measures are established. After the Survey Unit isolation and controls are in place, grid points are identified for the direct measurements/samples, and the area scan grid is identified.

Data is collected and any required investigations are performed.

2.4 Survey Data Assessment The final stage of the FSS program involves assessment of the data collected to ensure the validity of the results, to demonstrate achievement of the survey plan objectives, and to validate Survey Unit classification. During this phase, the DQOs and survey design are reviewed for consistency between DQO output, sampling design and other data collection documents. A preliminary data review is conducted to include: checking for problems or anomalies, calculation of statistical quantities and preparation of graphical representations for data comparison. Statistical tests are performed, if required, and the assumptions for the tests are verified. Conclusions are then drawn from the data, and any deficiencies or recommendations for improvement are documented.

2.5 Quality Assurance and Quality Control Measures YNPS FSS activities are implemented and performed under approved procedures, and the YNPS Quality Assurance Project Plan (QAPP) assures plans, procedures and instructions have been followed during the course of FSS, as well as providing guidance for implementing quality control measures specified in the YNPS LTP.

3.0 SURVEY AREA INFORMATION 3.1 Survey Area Description SVC-01 is comprised of the service building foundation that was exposed during excavation campaigns to remove radiologically contaminated soil and PCB-contaminated soil from the "alley way", Survey Unit NOL-01-04. Survey Unit SVC-3

Report No.: YNPS-FSS-SVC-01-00 01-18 serves as the north boundary for Survey Unit NOL-01-04. It is approximately 512 ft2 (48m2) of concrete surface area. It is the sole surviving SVC Survey Unit, the remainder was demolished and disposed of as non-radioactive, PCB waste.

3.2 History of Survey Area The Service Building is a structure that had been divided into three survey areas:

SVC-01, SVC-02, and SVC-03. These survey areas are delineated based upon their construction, the systems present and operational history. SVC-02, SVC-03, and SCV-01-01 through SVC-01-17 were demolished and shipped off site as non-radioactive, PCB waste. A small portion of SCV-01 remained, SVC-01-18. The use of the Service Building spaces in survey area SVC-01 has changed over the life of the plant. The spaces identified as SVC-01 have always been maintained as a clean area.

3.3 Division of Survey Area into Survey Units SVC-01 has a single Survey Unit, SVC-01-18 which is a Class I Survey Unit. SCV-01-01 through SVC-01-17 nomenclature was assigned to Survey Units that were demolished and disposed of as non-radioactive, PCB waste.

SCV-01-01 through SVC-01-17 no longer exists on site, and will not be addressed.

4.0 SURVEY UNIT INFORMATION 4.1 Summary of Radiological Data Since Historical Site Assessment (HSA) 4.1.1 Chronology and Description of Surveys Since HSA The FSS survey of SVC-0 1-18 was performed between November 3 0th, 2005 and December Ist, 2005.

4.1.2 Radionuclide Selection and Basis During the initial DQO process, Co-60 was identified as the radiological nuclide of concern due to its more restrictive DCGL value when compared to Cs-137 (sampling of soil adjacent to the concrete indicated a relationship of approximately 80%

Co-60 to 20%

Cs-137).

Characterization and survey data from the SVC building indicate no other LTP-specified radionuclides warrant consideration in the SVC-01 Survey Unit.

4.1.3 Scoping & Characterization 4

Report No.: YNPS-FSS-SVC-01-00 Prior to commencing demolition activities in SVC-01, a pre-demolition survey was performed in accordance with AP-0831, Administrative Program for Radiological and Non-Radiological Characterization Surveys.

The results of this survey identified no radiological contamination present within the bounds of SVC-01. This survey also served as the survey needed for free release of the demolition materials. FSS planning for unit SVC-01-18 used the survey data from adjacent Survey Unit SVC-01-10.

4.2 Basis for Classification Based upon the radiological condition of this Survey Area identified in the operating history and as a result of the decommissioning activities performed to date, Survey Area SVC-01 is identified as a Class I Area.

4.3 Remedial Actions and Further Investigations No remedial action or investigations were required.

4.4 Unique Features of Survey Area Survey Area SVC-01 exhibited surface characteristics ranging from smooth surfaces to heavily remediated irregular surfaces. Most of the pits and irregularities increased the source-to-detector distance by approximately 1/4 - 1/2 inch, although some increase it as much as I - 2 inches. These types of irregularities in the concrete surfaces were taken into account through the efficiency factor applied to the measurements collected with the HP-100. Technical report YA-REPT-00-015-04 (Appendix B) provides instrument efficiency factors (ci) for various source-to-detector distances.

The q

value for a source-to-detector distance of 1 inch was selected as a representative efficiency for data collected with the HP-100 from the irregular surfaces because it accounts for the / 2 inch stand-off and the most common depth of pits and surface irregularities (1/4 - V2 inch). In contrast to the irregular surfaces, the vertical walls of the structures are relatively smooth. Table 4.2 of the YA-REPT 015-04 (Appendix B) provides instrument efficiency factors (Ei) for various source-to-detector distances.

Detector efficiencies (HP-100C) were applied as follows:

smooth surface 0.0603 c/d, irregular surface 0.0373 c/d.

4.5 ALARA Practices and Evaluations An ALARA evaluation was developed for Survey Unit SVC-0I-18 which concluded that additional remediation was not warranted. This evaluation is found in Appendix C.

5.0 SURVEY UNIT FINAL STATUS SURVEY 5.1 Survey Planning 5

Report No.: YNPS-FSS-SVC-01-00 5.1.1 Final Status Survey Plan and Associated DQOs The FSS for SVC-01 Survey Unit was planned and developed in accordance with the LTP using the DQO process.

Form DPF-8856.1, found in YNPS Procedure 8856, "Preparation of Survey Plans," was used to provide guidance and consistency during development of the FSS Plan.

The FSS Plan can be found in Appendix A. The DQO process allows for systematic planning and is specifically designed to address problems that require a decision to be made in a complex survey design and, in turn, provides alternative actions.

The DQO process was used to develop an integrated survey plan providing the Survey Unit identification, sample size, selected analytical techniques, survey instrumentation, and scan coverage. The Sign Test was specified for non-parametric statistical testing for this Survey Unit, if required. The design parameters developed are presented below.

Table 2 Survey Area SVC-01 Design Parameters Survex Desi*n Parameter,;

Value Basis SVC-01-18 Area 48 m2 Class 1, <2,000 m2 Number of Direct Measurements 15 (calculated)

(x (Type I) = 0.05 (with direction to take more as space allows) f3 (Type 1I) 0.05 15+

7:

727dpm Relative Shift: 2 LBGR: 3,200 dpm Sample Area 3.2m2 Area / Sample #

Sample Grid Spacing: Triangular 1.91 m Square Root (Area/(0.866*Sample #))

Scan area 48 m2 Class I Area-100%

SPA-3 Scan Investigation Level

> Background Audible Class I Area: > DCGLemc 5.1.2 Deviations from the FSS Plan as Written in the LTP The FSSP design was performed to the criteria of the LTP; therefore, no LTP deviations with potential impact to this Survey Area need to be evaluated. However, during the DQA process, it was noted that the survey was designed to have a spacing of 6 foot 3 inches, but there was a typographical error in the FSSP that directed the survey to be performed at 63 inches, 12 inches smaller. This is more conservative grid spacing, so it does not affect the quality of the outcome, as 10 additional samples were added to the grid due to the smaller spacing. The result was more sample is a smaller gird pattern, which increases the statistical power of the survey.

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Report No.: YNPS-FSS-SVC-01-00 5.1.3 DCGL Selection and Use For the final evaluation of the SVC-01 Survey Area and throughout this report, the administrative acceptance criterion of 8.73 mRem/yr for Building Surface LTP-listed DCGL values has been applied. However, given that all of the remaining slab and foundation structure will be at least a three feet subsurface when site grading is complete and will be in such a state at license termination, the LTP, section 5.6.3.1.2, "Exterior Surfaces of Building Foundations," establishes the applicable guidance, as it addresses methods that may be applied to determine if subsurface structure surfaces will be acceptable by meeting LTP-required concrete volumetric DCGLs.

With the established LTP guidance, given that Co-60 and Cs-137 have been found to be the only radionuclides of significance in the area of concern, and conventional hand-held instrument survey criteria techniques being conservatively based on Co-60 beta emissions, performing a Class 1 survey applying Building Surface DCGLs has led to a very conservative approach in determining the final status of the Survey Unit. Additionally, applying this approach to evaluating subsurface conditions leaves no unanswered questions should future subsurface structure occupancy arise.

Table 3 DCGLw DCGLw Nuclide Bldg Surface Co-60 6.3E+03 dpm/100 cm2 equal to 8.73 mRem/y Cs-137 2.2E+04 dpm/100 cm2 equal to 8.73 mRem/y 5.1.4 Measurements Error tolerances and characterization sample population statistics drove the selection of the number of fixed point measurements.

15 measurements were needed in the event the Sign test may have been used.

In addition to the 15 statistical measurements needed, 10 additional samples were added to the statistical measurements.

The direct measurement sampling grid was developed as a systematic grid with spacing consisting of a triangular pitch pattern with a random starting point. Sample measurement locations are provided in Attachment A.

7

Report No.: YNPS-FSS-SVC-01-00 5.2 Survey Implementation Activities Table 3 provides a summary of daily activities performed during the Final Status Survey of Survey Unit in SVC-01.

Table 4 FSS Activity Summary for SVC-01 Survey Area

~Survev I nit

~

Date S

'"AcityLxi SVC-0 1-18 11-17-05 Performed walk-down of Survey Unit 11-17-05 Established Isolation and Controls 11-17-05 Performed Job Hazard Analysis 11-22-05 Performed Unit Classification 11-22-05 Performed Sample Quantity Calculations, established DQOs 11-23:05 Generated FFS Sample Plans 11-30-05 to 12-01-05 Initiated Scans, and Direct measurements.

09-09-06 Performed DQA, FSS Complete 5.3 Surveillance Surveys 5.3.1 Periodic Surveillance Surveys Upon completion of the FSS of Survey Area SVC-01, the Survey Unit footprint was placed into the program for periodic surveillance surveys on a quarterly basis in accordance with YNPS procedure DP-8860, "Area Surveillance Following Final Status Survey."

These surveys provide assurance that areas with successful FSS remain unchanged until license termination.

5.3.2 Resurveys No resurveys were performed.

5.3.3 Investigations No additional investigations were required for this Survey Unit due to surveillance surveys.

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Report No.: YNPS-FSS-SVC-O1-O0 5.4 Survey Results Direct measurement surveys indicated that no Survey Unit's systematic measurements exceeded the DCGLw, depicted in Attachment B.

Retrospective power curves were generated and demonstrated that an adequate number of measurements were collected to support the Data Quality Objectives. Therefore, the null hypothesis (Ho) (that the Survey Unit exceeds the release criteria) is rejected.

Table 5 Direct Measurement Summary (DPM/100cm2)

Saml5le DescriiAioti ActivitV SVC-01-18-001-F-FM 576 SVC-01-18-002-F-FM 809 SVC-01-18-003-F-FM 991 SVC-01-18-004-F-FM 825 SVC-01-18-005-F-FM 809 SVC-01-18-006-F-FM 892 SVC-01-18-007-F-FM 1254 SVC-01-18-008-F-FM 825 SVC-01-18-009-F-FM 2165 SVC-01-18-010-F-FM 875 SVC-01-18-011-F-FM 1024 SVC-01-18-012-F-FM 1605 SVC-01-18-013-F-FM 958 SVC-01-18-014-F-FM 1190 SVC-01-18-015-F-FM 742 SVC-01-18-016-F-FM 1041 SVC-01-18-017-F-FM 1804 SVC-01-18-018-F-FM 858 SVC-01-18-019-F-FM 958 SVC-01-18-020-F-FM 1041 SVC-01-18-021-F-FM 1200 SVC-01-18-022-F-FM 2460 SVC-01-18-023-F-FM 759 SVC-01-18-024-F-FM 560 SVC-01-18-025-F-FM 643 Max 2460 Average 1075 Standard Deviation 471 5.5 Data Quality Assessment The Data Quality Assessment phase is the part of the FSS where survey design and data are reviewed for completeness and consistency, ensuring the validity of the results, verifying that the survey plan objectives were met, and validating the classification of the Survey Unit.

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Report No.: YNPS-FSS-SVC-O1-O0 A preliminary data review was performed. The retrospective power curve possessed adequate power to pass the survey with the final standard deviation less than the projected standard deviation. The data set was within three standard deviations and displayed a normal dispersion about the mean. The quantile plot exhibits some asymmetry in the lower quartile due to the number of low values, however the posting plot does not clearly reveal any systematic spatial trends. The data set verifies the assumptions of the statistical test.

The sample design and the data acquired were reviewed and found to be in accordance with applicable YNPS procedures DP-886 1, "Data Quality Assessment";

DP-8856, "Preparation of Survey Plans"; DP-8853, "Determination of the Number and Locations of FSS Samples and Measurements"; DP-8857, "Statistical Tests";

DP-8865, "Computer Determination of the Number of FSS Samples and Measurements" and DP-8852, "Final Status Survey Quality Assurance Project Plan".

The Data Quality Assessment power curves, scatter, quantile and frequency plots are found in Attachment B. Posting Plots are found in Attachment A.

6.0 QUALITY ASSURANCE AND QUALITY CONTROL 6.1 Instrument QC Checks Operation of the E-600 w/SPA-3 was in accordance with DP-8535,"Setup and Operation of the Eberline E-600 Digital Survey Instrument," with QC checks preformed in accordance with DP-8540, "Operation and Source Checks of Portable Friskers." Instrument response checks were performed prior to and after use for the E-600 w/SPA-3. All instrumentation involved with the FSS of SVC-01 satisfied the above criteria for the survey. QC records are found in Attachment C.

6.2 Split Samples and Recounts DP-8864,"Split Sample Assessment for Final Status Survey" deals strictly with soil samples and provides no criteria for fixed-point measurements therefore no measurement comparison were made.

6.3 Self-Assessments No self-assessments were performed during the FSS of SVC-01.

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Report No.: YNPS-FSS-SVC-O1-O0

7.0 CONCLUSION

The FSS of SVC-01 has been performed in accordance with YNPS LTP and applicable FSS procedures.

Evaluation of the direct measurement data has shown none of the systematic direct measurements exceeded the DCGLw, depicted in Attachment B.

Retrospective power curves were generated and demonstrated that an adequate number of samples were collected to support the Data Quality Objectives. Therefore, the null hypothesis (H.) is rejected.

SVC-01 meets the objectives of the Final Status Survey.

Based upon the evaluation of the data acquired for the FSS, SVC-01 meets the release requirements set forth in the YNPS LTP. The Total Effective Dose Equivalent (TEDE) to the average member of the critical group does not exceed 25 mRem/yr, including that from groundwater. I OCFR20 Subpart E ALARA requirements have been met as well as the site release criteria for the administrative level DCGLs that ensure that the Massachusetts Department of Public Health's 10 mRem/yr limit will also be met.

11

Report No.: YNPS-FSS-SVC-01-00 List of Appendices Appendix A - YNPS-FSSP-SVC-01, "Final Status Survey Planning Worksheets Appendix B - YA-REPT-00-01 5-04, "Instrument Efficiency Determination for Use in Minimum Detectable Concentration Calculations in Support of the Final Status Survey at Yankee Rowe" Appendix C - ALARA Evaluations, SVC-0 I Appendix D -YA-REPT-00-018-05, "Use of In-situ Gamma Spectrum Analysis to Perform Elevated Measurement Comparison in Support of Final Status Surveys" List of Attachments Attachment A - Maps and Posting Plots Attachment B - Data Quality Assessment Plots and Curves Attachment C - Instrument QC Records (In the electronic version, every Table of Contents, Figures, Appendices and Attachments, as well as every mention of a Figure, Appendix or Attachment is a hyperlink to the actual location or document.)

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Final Status Survey Planning Worksheet Page 1 of4 GENERAL SECTION Survey Area #:

SVC-01 Survey Unit #:

18 Survey Unit Name:

Service Building Foundation - South Vertical Edge FSSP Number:

YNPS-FSSP-SVC01-18-00 PREPARATION FOR FSS ACTIVITIES Check marks in the boxes below signify affirmative responses and completion of the action.

1.1 Files have been established for survey unit FSS records.

z]

1.2 ALARA review has been completed for the survey unit.

z]

1.3 The survey unit has been turned over for final status survey. I]

1.4 An initial DP-8854 walkdown has been performed and a copy of the completed Survey Unit Walkdown Evaluation is in the survey area file.

M 1.5 Activities conducted within area since turnover for FSS have been reviewed.

[]

Based on reviewed information, subsequent walkdown:

[0 not warranted El warranted If warranted, subsequent walkdown has been performed and documented per DP-8854.

El OR The basis has been provided to and accepted by the FSS Project Manager for not performing a subsequent walkdown.

El 1.6 A final classification has been performed.

Z]

Classification: CLASS 1 I]

CLASS 2 El CLASS 3 El DATA QUALITY OBJECTIVES (DQO) 1.0 Statement of problem:

The service building foundation was exposed during the excavation campaigns to remove radiologically contaminated soil and PCB-contaminated soil from the "alley way" (unit NOL01-04). Survey Unit SVCO1-18 serves as the north boundary for survey unit NOLO 1-04. It is approximately 512 ft2 (48m 2) of concrete surface area. The data collected under this plan will be used to determine whether or not residual plant-related radioactivity on the exposed concrete surface of Survey Unit SVC01-18 meets LTP release criteria.

The planning team for this effort consists of the FSS Project Manager, FSS Radiological Engineer, FSS Field Supervisor, and FSS Technicians.

The FSS Radiological Engineer will make primary decisions with the concurrence of the FSS Project Manager.

2.0 Identify the decision:

Does residual plant-related radioactivity, if present in the survey unit, exceed LTP release criteria? Alternative actions that may be implemented in this effort are investigations and remediation followed by re-surveying.

3.0 Identify the inputs to the decision:

Sample media: concrete Types of measurements: Fixed-point measurements, beta scans, and gamma scans.

Radionuclides-of-concern: Co-60 (assumed as a conservative measure for the reasons stated in YNPS-FSSP-BRTO 1-10-00).

FSS planning for unit SVCOI-18 used the FSS data from unit BRT01-10 because there is no reason to expect the radiological characteristics of SVC01-18 to be different from BRT01-10 (the 2 units are adjacent).

The mean value of fixed-point measurements from BRTOI-10 was 1.8E3 dpm/100cm2 + 4.8E2 dpmr/1OOcm 2. The FSS net measurements ranged from no detectable to 2.8E3 dpm/1OOcm 2 (or 44% of the DCGL for Co-60).

Average radiation level: 1.8E3 dpm/1OOcm 2 (mean of FSS data for BRTO1-10)

Standard deviation (a): 4.8E2 dpm/I00cm 2 (standard deviation of FSS data for BRTOI-10)

DPF-8856.1 Page 1 of4 YNPS-FSSP-SVCO1-1 8-00

DCGLs:

(1) Applicable DCGLw: 6.3E3 dpm/100cm 2 (Co-60 assumed)

Note: the DCGLw value corresponds to 8.73 mrem/y.

Although most of the concrete of Survey Unit SVC01-18 has a relatively smooth surface, some localized areas contain pits and irregular surfaces (typical depths in these areas are approximately 1/44 -

1/2 inch, although some increase it as much as 1 inch), which will increase the source-to-detector distance for some localized areas under the 100cm 2 window of the detector.

These irregularities in the concrete surfaces will be taken into account through the efficiency factor applied to the measurements collected with the HP-100. Technical report YA-REPT-00-015-04 provides instrument efficiency factors (&i) for various source-to-detector distances.

The si value for a source-to-detector distance of 1 inch was selected as a representative efficiency for data collected with the HP-100 from the pitted/irregular surfaces because it accounts for the '/2 inch stand-off and the most common depth of pits and surface irregularities (1/4 - V2 inch). In contrast to the localized pitted/irregular areas, most of the concrete of the east vertical wall is relatively smooth. The si value for a distance of 1/2/2 inch will be applied to HP-100 data collected from smooth concrete surfaces. The efficiency factors provided in YA-REPT 015-04 are used below:

Fi = 0.2413 c/e for smooth concrete surfaces (reflects a source to detector distance = /2 inch), and

= 0.149 c/e for pitted/irregular surfaces (reflects a source to detector distance = 1 inch) s = 0.25 e/d (consistent with the Co-60 assumption made in this plan) total efficiency for smooth surface = F, Sc = 0.2413 c/e. 0.25 e/d = 0.0603 c/d total efficiency for pitted/irregular surfaces = Fi

• e, = 0.149 c/e- 0.25 e/d = 0.0373 c/d (2) Gross measurement DCGL_ (for HP-100): 6.3E3 dpM/rlOOcm 2 for smooth concrete surface: 6.3E3 dpm/100cm2

• 0.0603 c/d = 3.8E2 cpm/100cm 2 for pitted/irregular surface: 6.3E3 dpm/100cm2

• 0.0373 c/d = 2.3E2 cpm/1OOcm 2 (3) Applicable DCGLp. c for fixed-point measurements: DCGLW

• AF = 6.3E3 dpm/100cm 2 *2.4 = 1.5E4 dpm/1OOcm 2 for smooth concrete surface: 1.5E4 dpm/1OOcm 2

• 0.0603 c/d = 9.1E2 cpm/1OOcm 2 for pitted/irregular surface: 1.5E4 dpm/100cm2

• 0.0373 c/d = 5.6E2 cpm/100cm 2 Note: the DCGL and DCGLEMC value refer to above-background radioactivity.

Investigation Levelfor fixed-point measurement.-

for smooth (i.e., vertical side) concrete surface: >9.1 E2 cpM/1OOcm 2 above background for pitted/irregular (i.e., top) concrete surface: >5.6E2 cpm/100cm2 above background Investigation Level for HP-100 scan: Reproducible indication above background using the audible feature with headphones Investigation Level for SPA-3 scan: Reproducible indication above background using the audible feature with headphones Scan coverage: Beta scan with HP-100: 100% of the accessible concrete surface area on the vertical walls. Supplemental SPA-3 scans on the irregular surfaces of the vertical walls and cracks in the concrete MDCR for HP-100: The accompanying table provides MDCR values by various background levels.

The expected background for the HP-100 range is 100 - 400 cpm.

MDC(IDCGLEMc ) for HP-100 scans: The accompanying table provides MDC(fDCGLEMc) values by various background levels.

QC checks and measurements: QC checks for the survey instruments will be performed in accordance with DP-8534. Pre-and post-use instrument QC checks will be performed.

4.0 Define the boundaries of the survey:

Boundaries of SVCO1-18 are defined by the termination of the vertical surface of the NE section of the turbine building foundation. The survey will be performed under weather conditions that permit instrument operation and surveying.

5.0 Develop a decision rule:

(a) If all the FSS data show that residual levels of plant-related radioactivity are below the DCGLW, reject the null hypothesis (i.e., Survey Unit meets the release criteria).

(b) If the investigation level is exceeded, then perform an investigation.

(c) If the average of the FSS measurements is below the DCGLW, but some individual measurements exceed the DCGLW, then apply a statistical test as the basis for accepting or rejecting the null hypothesis.

(d) If the average of the FSS measurements exceeds the DCGLW, then accept the null hypothesis (i.e., Survey Unit fails DPF-8856.1 YNPS-FSSP-SVC01-18-00 Page 2 of 4

to meet the release criteria).

6.0 Specify tolerable limits on decision errors:

Null hypothesis: Residual plant-related radioactivity in Survey Unit SVCO 1-18 exceeds the release criteria.

Probability of type I error: 0.05 Probability of type II error: 0.05 7.0 LBGR: 6.3E3 dpm/100 cm2 - 2 = 3.2E3 dpm/100 cm2 8.0 Optimize Design:

Type of statistical test: WRS Test E]

Sign Test R1 Basis including background reference location (if WRS test is specified): N/A Number samples (per DP-8853): 15 Biased Measurements: None GENERAL INSTRUCTIONS

1. The FSS Field Supervisor is responsible for contacting the QA Department regarding the FSS activities identified as QA notification points.

2. Mark the sampling points at the locations as follows:

(a) Locate and mark the random start point for the grid at a point 9ft, 5inches from the east end of the service building foundation and I ft, 11 inches from the top of the foundation.

(b) Locate and mark other fixed-point measurement locations at intervals of 63 inches to the west and east of the random start location. These locations are also 1 ft, 11 inches from the top of the foundation.

(c) If a measurement location shown in Figure 1 falls at a location that is obstructed (e.g., by soil) or from which a fixed-point measurement cannot be collected, select an alternate location in accordance with DP-8856.

Note: The dimensions used in planning allow the collection of 19 fixed-point measurements. It may be necessary to add or delete some measurement locations based on the actual length of the survey unit. These adjustments to the grid are acceptable as long as the random start point is used, the general grid structure is maintained, and at least 15 fixed-point measurement locations are identified.

3. Collect a series of ambient background measurements in accordance with step B.l.c in DP-8866 with the following variation of step B.1.c.2) using the HP-100 that is to be used to collect the fixed-point measurements:

(a) Cover the detector with a 1/8-inch Lucite (or equivalent) shield and collect 7 one-minute readings with the shielded detector facing towards but approximately 1 m from the concrete surface (and approximately I m above the soil) at the west end, center, and east end of the survey unit.

(b) Record the background data on the attached Form 1(even if the measurement was logged).

4. Collect a fixed-point (1r-min) measurement in accordance with DP-8534 at each of the marked locations.

(a) Designate the fixed-point measurements as SVC-01-18-001-F-FM through SVC-01-18-019-F-FM, as shown in Figure 1.

(b) Record each fixed-point measurement "as read" (in units of cpm) on the attached Form 2 (even if the reading was logged).

(c) When recording the measurements on Form 2, identify those measurements collected from an irregular concrete surface with an asterisk (*).

(d) Note on Form 2 any measurement location that was omitted or added due to field adjustments of the planned grid.

5. Perform HP-100 and SPA-3 scans as described in the Specific Instructions.

6. Survey instrument: Operation of the E-600 will be in accordance with DP-8534. Pre-and post-use QC checks for survey instruments are to be performed.

7. The applicable job hazards associated with this survey will be addressed in the Yankee Rowe Project Daily Activity Plan and reviewed by the FSS Field Supervisor during the pre-survey briefing.

8. All personnel participating in this survey shall be trained in accordance with DP-8868.

SPECIFIC INSTRUCTIONS

1. Beta scans:

(a) Perform the HP-100 scans by moving the detector at a speed no greater than 2 inches per second, using a 1/2/2 inch

-8856.1 YNPS-FSSP-SVC01-18-00 DPF-Page 3 of 4

standoff.

(b) FSS Technicians will wear headphones while scanning and the survey instrument will be in the rate-meter mode.

Surveyors will listen for upscale readings and respond to readings that exceed the investigation level.

(c) If the HP-100 scan investigation level is exceeded:

(1) confirm that the elevated scan reading is reproducible and not the result of a nearby source (e.g., waste pile or container),

(2) if a nearby source is identified, have it removed or shielded, document the finding on DP-8856.2, and repeat the

scan, (3) if reproducible and not caused by a nearby source, collect a fixed-point measurement at the location of the greater-than-investigation level reading, (4) the designation for a fixed-point measurement collected during a first-level investigation will be SVC-01 0XX-F-FM-I, where "XX" continues the numbering sequence for fixed-point measurements. Record all investigation fixed-point measurements "as read" (in units of cpm) on the attached Form 2 (even if the measurement was logged).

(5) mark the location of the fixed-point measurement location for further investigation if it exceeds the investigation level for a fixed-point measurement.

If a fixed-point measurement location has been identified for further investigation, the investigation will be conducted under a separate survey plan.

(d) The FSS Field Supervisor will record information relevant to the HP-100 scans on DPF-8856.2.

2. Perform SPA-3 scans:

(a) Perform SPA-3 of the irregular surfaces and over cracks in the concrete by moving the detector slowly (no greater than 0.25m/s) and keeping it < 3 inches from the surface.

(b) FSS Technicians will wear headphones while scanning and the survey instrument will be in the rate-meter mode.

Surveyors will listen for upscale readings and respond to readings that exceed the SPA-3 investigation level.

(c) If a SPA-3 reading exceeds the investigation level:

(1) confirm that the above-background indication is reproducible and cannot be attributed to a nearby source, (2) if a nearby source is identified, have it removed or shielded, document the finding on DP-8856.2, and repeat the

scan, (3) if the reading is reproducible and not caused by a nearby source, collect a fixed-point measurement with the HP-100 at the highest reading observed during the scan and clearly mark that location.

(4) Designate the investigation fixed-point measurement as described in step I (c)(4) above.

(5) Record all investigation fixed-point measurements "as read" (in units of cpm) on the attached Form 2 (even if the measurement was logged). If further investigation is required, it will be conducted under a separate survey plan.

(d) The FSS Field Supervisor will record information relevant to the SPA-3 scans on DPF-8856.2 NOTIFICATION POINTS QA notification* point(s) (y/n) _-y (1) Date/time of initial pre-survey briefing OA signature:

(2) Date/time of commencement of HP-100 measurements QA signature:

(3) Date/time of commencement of SPA-3 measurements QA signature:

(4) Time(s) of daily pre-shift briefing QA signature:

(for each shift that the FSS is performed)

Voice mail notification or E-mail notification to Trudeau@yankeerowe.com with a copy to Marchi@cyapco.com satisfies this step.

FSI point(s) (y/n) n Specify:

Prepared by 0, 6 Date /1-2 3-05--

FSS Radiological Engineer Reviewed by, Date-z 7

C_

Date F S Radio log gangine r Approved by beC, &.,

Date U 123/0, FSS Proqjct Manager DPF-8856. 1 Page 4 of 4 YNPS-FSSP-SVCOI-18-00

MDCR/MDC Table for Survey Unit SVC01 -18 Background scan speed MDCR (cpm)

(in/s)

(cpm)

MDC(fDCGL(emc))

400 2

151 0.38 500 2

169 0.42 1000 2

239 0.60 detector = HP-1 00 (effic factor for 1 in)

MDC(fDCGL)-MDCR table_SVCOI-18_1o effic

Form 1 Background Data Survey Unit SVCO1-18 Instrument No.:

Measurement Measurement Location No.

(cpm)

BG location 1 1

2 3

4 5

6 7

BG location 2 1

2 3

4 5

6 7

BG location 3 1

2 3

4 5

6 7

YNPS-FSSP-SVCO1-18-00

Form 2 FSS Fixed-Point Measurements Survey Unit SVCO1-18 Instrument No.:

Measurement Location (cPm/IOOcm 2)

SVC-01-18-001-F-FM SVC-01-18-002-F-FM SVC-01-18-003-F-FM SVC-01-18-004-F-FM SVC-01-18-005-F-FM SVC-01-18-006-F-FM SVC-01-18-007-F-FM SVC-01-18-008-F-FM SVC-01-18-009-F-FM SVC-01-18-010-F-FM SVC-0 1-18-011-F-FM SVC-01-18-012-F-FM SVC-0 1-18-013-F-FM SVC-01-18-014-F-FM SVC-01-18-015-F-FM SVC-01-18-016-F-FM SVC-01-18-017-F-FM SVC-01-18-018-F-FM SVC-01-18-019-F-FM

-4 i

YNPS-FSSP-SVCO1-18-00

TECHNICAL REPORT TITLE PAGE 0

Copy Instrument Efficiency Determination for Use in Minimum Detectable Concentration Calculations in Support of the Final Status Survey at Yankee Rowe Title YA-REPT-00-015-04 REV. 0 Technical Report Number Approvals\\

"IN (Print & Sign Name)

Preparer:(

Review4:

OO Approver (Clonizant Manager):

Date:

1o.0 q*-

Ao Date: ( oio*,04 Date:

/, /7/0, YA-REPT-OO-0 15-04 Rev. 0 Page 1 of 26

/

/

TABLE OF CONTENTS Page 1.0 Executive Summary:........................................................................................

4 2.0

==

Introduction:==

............. 4 3.0 Calibration Sources:.......................................................

4 4.0 Efficiency Determination:..............................................

................................... 6 4.1 Alpha and Beta Instrument Efficiency (si):........................................................ 6 4.2 Source to Detector Distance Considerations:................................................... 7 4.2.1 Methodology................................................................................. 7 4.3 Source (or Surface) Efficiency (s,) Determination:............................................ 8 5.0 Instrument Conversion Factor (E) (Instrument Efficiency for Scanning):.............................. 9 6.0 Applying Efficiency Corrections Based on the Effects of Field Conditions for Total Efficiency:... 9 7.0 C onclusion:.................................................................................................

10 8.0 R eferences:....................................................................................................

11 Tables Table 3.1 Nuclides and Major Radiations: Approximate Energies....................................... 5 Table 4.1 Instrument Efficiencies (ci).......................................................................

7 Table 4.2 Source to Detector Distance Effects on Instrument Efficiencies for a- 03 Emitters........... 8 Table 4.3 Source Efficiencies as listed in ISO 1703-1:.................................................... 8 Table 5.1 Energy Response and Efficiency for Photon Emitting Isotopes:............................. 9 Appendix APPENDIX A MicroShield, SPA-3 Soil scan - 28 cm radius lpCi/cm3 Co-60..................... 12 APPENDIX B Microsoft Excel Co-60 Calculation Sheet............................................... 13 APPENDIX C MicroShield, SPA-3 Soil scan - 28 cm radius lpCi/cm3 Nb-94................... 14 APPENDIX D Microsoft Excel Nb-94 Calculation Sheet............................................. 15 YA-REPT-00-0 15-04 Rev. 0 Page 2 of 26

APPENDIX E APPENDIX F APPENDIX G APPENDIX H APPENDIX I APPENDIX J APPENDIX K APPENDIX L APPENDIX M APPENDIX N APPENDIX 0 MicroShield, SPA-3 Soil scan-28 cm radius lpCi/cm3 Ag-108m................. 16 Microsoft Excel Ag-I 08m Calculation Sheet............................................. 17 MicroShield, SPA-3 Soil scan - 28 cm radius 1 pCi/cm3 Sb-125.................... 18 Microsoft Excel Sb-125 Calculation Sheet................................................ 19 MicroShield, SPA-3 Soil scan - 28 cm radius lpCi/cm3 Cs-134................... 20 Microsoft Excel Cs-134 Calculation Sheet..............................

21 MicroShield, SPA-3 Soil scan-28 cm radius lpCi/cm3 Cs-137................... 22 Microsoft Excel Cs-137 Calculation Sheet................................................ 23 MicroShield, SPA-3 Soil scan - 28 cm radius 1pCi/cni3 Cs-137................... 24 Microsoft Excel Cs-137 Calculation Sheet............................................. 25 Calculated Energy Response............................................................. 26 YA-REPT-00-015-04 Rev. 0 Page 3 of 26

1.0 Executive Summary:

The minimum detectable concentration (MDC) of the field survey instrumentation is an important factor affecting the quality of the final status survey (FSS). The efficiency of an instrument inversely impacts the MDC value. The objective of this report is to determine the instrument and source efficiency values used to calculate MDC. Several factors were considered when determining these efficiencies and are discussed in the body of this report. Instrument efficiencies (si), and source efficiencies (Qs), for alpha beta detection equipment under various field conditions, and instrument conversion factors (Ei), for gamma scanning detectors were determined and the results are provided herein.

2.0

==

Introduction:==

Before performing Final Status Surveys of building surfaces and land areas, the minimum detectable concentration (MDC) must be calculated to establish the instrument sensitivity. Table 5.4 of the License Termination Plan (LTP) [8.6] lists the available instrumentation and nominal detection sensitivities; however for the purposes of this basis document, efficiencies for the 100cm 2 gas proportional and the 2"x2" NaI (TI) detectors will be determined. Efficiencies for the other instrumentation listed in the LTP shall be determined on an as needed basi's. The 100 cm 2 gas propoitional probe will be used to perform surveys (i.e. fixed point measurements). A 2" x2" Nal (TI) detector will be used to perform gamma surveys (i.e., surface scans) of portions of land areas and possibly supplemental structural scans at the Yankee Rowe site. Although surface scans and fixed point measurements can be performed using the same instrumentation, the calculated MDCs will be quite different. MDC is dependent on many factors and may include but is not limited to:

" instrument efficiency

• background

• integration time

• surface type

" source to detector geometry

" source efficiency A significant factor in determining an instrument MDC is the total efficiency, which is dependent on the instrument efficiency, the source efficiency and the type and energy of the radiation. MDC values are inversely affected by efficiency, as efficiencies increase, MDC values will decrease. Accounting for both the instrument and source components of the total efficiency provides for a more accurate assessment of surface activity.

3.0 Calibration Sources:

For accurate measurement of surface activity it is desirable that the field instrumentation be calibrated with source standards similar to the type and energy of the anticipated contamination. The nuclides listed in Table 3.1 illustrate the nuclides found in soil and building surface area DCGL results that are listed in the LTP.

Instrument response varies with incident radiations and energies; therefore, instrumentation selection for field surveys must be modeled on the expected surface activity. For the purposes of this report, isotopes with max beta energies less than that of C-14 (0.158 MeV) will be considered difficult to detect (reference table 3.1). The detectability of radionuclides with max beta energies less than 0.158 MeV, utilizing gas proportional detectors, will be negligible at typical source to detector distances of approximately 0.5 YA-REPT-00-015-04 Rev. 0 Page 4 of 26

inches. The source to detector distance of 1.27 cm (0.5 inches) is the distance to the detector with the attached standoff (DP-8534 "Operation and Source Checks of Proportional Friskers")[8.5]. Table 3.1 provides a summary of the LTP radionuclides and their detectability using Radiological Health Handbook

[8.4] data.

Table 3.1 Nuclides and Major Radiations: Approximate Energies (Reference 8.4)

Nuclide a Energy Ep., (MeV)

Average Photon Energy (MeV) a Detectable.

0 Detectable y

(MeV)

E, W/ Gas w/ Gas Detectable (MeV)

Proportional Proportional w/ Nal 2x2" H-3 0.018 0.005 C-14 0.158 0.049 Fe-55 0.23 (0.004%)

bremsstrahlung Co-60 0.314 0.094 1.173 (100%), 1.332 (100%)

Ni-63 0.066 0.017 Sr-90 0.544 0.200 2.245 (Y-90) 0.931 Nb-94 0.50 0.156 0.702 (100%), 0.871 (100%)

Tc-99 0.295 0.085 Ag-1.65 (Ag-0.624 0.434 (0.45%), 0.511 108m 108)

(Ag-(0.56%)

108) 0.615 (0.18%), 0.632 (1.7%)

Sb-125 0.612 0.084 0.6, 0.25, 0.41, 0.46, 0.68, 0.77, 0.92, 1.10, 1.34 Cs-I 34 1.453 0.152 0.57 (23%), 0.605 (98%)

0.796 (99%), 1.038 (1.0%)

1.168 (1.9%), 1.365 (3.4%)

Cs-137 1.167 0.195 0.662 (85%) Ba-137m*X-

• /

rays Eu-152 1.840 0.288 0.122 (37%), 0.245 (8%)

0.344 (27%), 0.779 (14%)

0.965 (15%), 1.087 (12%)

1.113 (14%), 1.408 (22%)

Eu-154 1.850 (10%)

0.228 Eu-155 0.247 0.044 0.087 (32%), 0.105 (20%)

Pu-238 5.50 (72%)

0.099 (8E-3%)

5.46 (28%)

0.150 (1E-3%)

0.77 (5E-5%)

Pu-239 5.16 (88%)

0.039 (0.007%), 0.052 5.11 (11%)

(0.20%), 0.129 (0.005%)...

Pu-241 4.90 0.021 0.005 0.145 (1.6E-4%)

(0.0019%)

4.85 (0.0003%)

Am-241 5.49 (85%)

0.060 (36%), 0.101 5.44 (13%)

(0.04%)...

Cm-243 6.06 (6%)

0.209 (4%), 0.228 (12%),

/

5.99 (6%)

0.278 (14%)

5.79 (73%)

5.74 YA-REPT-00-015-04 Rev. 0 Page 5 of 26

NUREG-1507 and ISO 7503-1 provide guidance for selecting calibration sources and their use in determining total efficiency. It is common practice to calibrate instrument efficiency for a single beta energy; however the energy of this reference source should not be significantly greater than the beta energy. of the lowest energy to be measured.

Tc-99 (0.295 MeV max) and Th-230 (4.68 MeV at 76% and 4.62 MeV at 24%) have been selected as the beta and alpha calibration standards respectively, because their energies conservatively approximate the beta and alpha energies of the plant specific radionuclides.

4.0 Efficiency Determination:

Typically, using the instrument 47 efficiency exclusively provides a good approximation of surface activity. Using these means for calculating the efficiency often results in an under estimate of activity levels in the field. Applying both the instrument 2n efficiency and the surface efficiency components to determine the total efficiency allows for a more accurate measurement due to consideration of the actual characteristics of the source surfaces. ISO 7503-1 [8.2] recommends that the total surface activity be calculated using:

RS-B - RB where:

A, is the total surface activity in dpm/cm2, Rs+B is the gross count rate of the measurement in cpm, RB is the background count rate in cpm, si is the instrument or detector 27u efficiency 8, is the efficiency of the source W is the area of the detector window (cm 2) 4.1 Alpha and Beta Instrument Efficiency (Qi):

Instrument efficiency (sq) reflects instrument characteristics and counting geometry, such as source construction, activity distribution, source area, particles incident on the detector per unit time and therefore source to detector geometry. Theoretically the maximum value of is 1.0, assuming all the emissions from the source are 2a and that all emissions from the source are detected. The ISO 7503-1 methodology for determining the instrument efficiency is similar to the historical 47 approach; however the detector response, in cpm, is divided by the 2a surface emission rate of the calibration source. The instrument efficiency is calculated by dividing the net count rate by the 2a surface emission rate (q 2,,)

(includes absorption in detector window, source detector geometry). The instrument efficiency is expressed in ISO 7503-1 by:

YA-REPT-00-015-04 Rev. 0 Page 6 of 26

RsB - RB q2x where:

Rs+B is the gross count rate of the measurement in cpm, RB is the background count rate in cpm, q 2, is the 2nr surface emission rate in reciprocal seconds Note that both the 27z surface emission rate and the source activity are usually stated on the certification sheet provided by the calibration source manufacturer and certified as National Institute of Standards and Technology (NIST) traceable. Table 4.1 depicts instrument efficiencies that have been determined during calibration using the 27c surface emission rate of the source.

Table 4.1 Instrument Efficiencies (ei)

Source Emission Active Area of Effective Area 100 cm 2 Gas Proportional Source (cmr2) of Detector HP-100 Instrument Efficiency (zn)

(Contact)

Tc-99 15.2 100 cm 2 0.4148 Th-230 a

15.2 100 cm2 0.5545 4.2 Source to Detector Distance Considerations:

A major factor affecting instrument efficiency is source to detector distance. Consideration must be given to this distance when selecting accurate instrument efficiency. The distance from the source to the detector shall to be as close as practicable to geometric conditions that exist in the field. A range of source to detector distances has been chosen, taking into account site specific survey conditions. In an effort to minimize the error associated with geometry, instrument efficiencies have been determined for source to detector distances representative of those survey distances expected in the field. The results shown in Table 4.2 illustrate the imposing reduction in detector response with increased distance from the source. Typically this source to detector distance will be 0.5 inches for fixed point measurements and 0.5 inches for scan surveys on flat surfaces, however they may differ for other surfaces. Table 4.2 makes provisions for the selection of source to detector distances for field survey conditions of up to 2 inches. If surface conditions dictate the placement of the detector at distances greater than 2 inches instrument efficiencies will be determined on an as needed basis.

4.2.1 Methodology

The practical application of choosing the proper instrument efficiency may be determined by averaging the surface variation (peaks and valleys narrower than the length of the detector) and adding 0.5 inches, the spacing that should be maintained between the detector and the highest peaks of the surface. Select the source to detector distance from Table 4.2 that best reflects this pre-determined geometry.

YA-REPT-00-015-04 Rev. 0 Page 7 of 26

Table 4.2 Source to Detector Distance Effects on Instrument Efficiencies for a-f Emitters Source to Detector Instrument Efficiency (Ci)

Distance (cm)

Tc-99 Th-230 Distributed Distributed Contact 0.4148 0.5545 1.27 (0.5 in) 0.2413 0.1764 2.54 (1 in) 0.1490 0.0265 5.08 (2 in) 0.0784 0.0002 4.3 Source (or Surface) Efficiency (c.) Determination:

Source efficiency (s), reflects the physical characteristics of the surface and any surface coatings. The source efficiency is the ratio between the number of particles emerging from surface and the total number of particles released within the source. The source efficiency accounts for attenuation and backscatter. Es is nominally 0.5 (no self-absorption/attenuation, no backscatter)-backscatter increases the value, self-absorption decreases the value. Source efficiencies may either be derived experimentally or simply selected from the guidance contained in ISO 7503-1. ISO 7503-1 takes a conservative approach by recommending the use of factors to correct for alpha and beta self-absorption/attenuation when determining surface activity. However, this approach may prove to be too conservative for radionuclides with max beta energies that are marginally lower than 0.400 MeV, such as Co-60 with a P3max of 0.314 MeV. In this situation, it may be more appropriate to determine the source efficiency by considering the energies of other beta emitting radionuclides. Using this approach it is possible to determine weighted average source efficiency. For example, a source efficiency of 0.375 may be calculated based on a 50/50 mix of Co-60 and Cs-137. The source efficiencies for Co-60 and Cs-137 are 0.25 and 0.5 respectively, since the radionuclide fraction for Co-60 and Cs-137 is 50% for each, the weighted average source efficiency for the mix may be calculated in the following manner:

(0.25XO.5)+ (0.5Xo.5) = 0.375 Table 4.3 lists guidance on source efficiencies from ISO 7503-1.

Table 4.3 Source Efficiencies as listed in ISO 7503-1

> 0.400 MeVma

< 0.400 MeVma, Beta emitters e,= 0.5 es = 0.25 Alpha emitters

% = 0.25 s, = 0.25 It should be noted that source efficiency is not typically addressed for gamma detectors as the value is effectively unity.

YA-REPT-00-0 15-04 Rev. 0 Page 8 of 26

5.0 Instrument Conversion Factor (E) ( Instrument Efficiency for Scanning):

Separate modeling analysis (MicroshieldTM) was conducted using the common gamma emitters with a concentration of 1 pCi/g of uniformly distributed contamination throughout the volume. MicroShield is a comprehensive photon/gamma ray shielding and dose assessment program, which is widely used throughout the radiological safety community. An activity concentration of I pCi/g for the nuclides was entered as the source term. The radial dimension of the cylindrical source was 28 cm, the depth was 15 cm, and the dose point above the surface was 10 cm with a soil density of 1.6 g/cm 3. The instrument efficiency when scanning, Ei, is the product of the modeled exposure rate (MicroShieldTM ) in mRhr-1/pCi/g for and the energy response factor in cpm/mR/hr as derived from the energy response curve provided by Eberline Instruments (Appendix 0). Table 5.1 demonstrates the derived efficiencies for the maj or gamma emitting isotopes listed in Table 3.1.

TABLE 5.1 Energy Response and Efficiency for Photon Emitting Isotopes Isotope Calculations for Ei Ei See appendix A through L (cpm/pCi/g)

Co-60 See Appendix Aand B 379 Nb-94 See Appendix C and D 416 Ag-108m See Appendix E and F 637 Sb-125 See Appendix G and H 210 Cs-134 See Appendix I and J 506 Cs-137 See Appendix K and L 188 Eu-152 See Appendix M and N 344 When performing gamma scan measurements on soil surfaces the effective source to detector geometry is as close as is reasonably possible (less than 3 inches).

6.0 Applying Efficiency Corrections Based on the Effects of Field Conditions for Total Efficiency:

The total efficiency for any given condition can now be calculated from the product of the instrument efficiency ei and the source efficiency s,.

etot = 6i X CS The following example illustrates the process of determining total efficiency. For this example we will assume the following:

• Surface activity readings need to be made in the Primary Auxiliary Building (PAB) on the concrete wall surfaces using the E-600 and C-100 gas proportional detector.

" Data obtained from characterization results from the PAB indicate the presence of beta emitters with energies greater than 0.400 Mev.

" The source (activity on wall) to detector distance is 1.27 cm (0.5 in detector stand off). To calculate the total efficiency, etot, refer to Table 4.2 "Source to Detector Distance Effects on Instrument Efficiencies for a- 03 Emitters" to obtain the appropriate 9i value.

• Contamination on all surfaces is distributed relative to the effective detector area.

YA-REPT-00-015-04 Rev. 0 Page 9 of 26

- When performing fixed point measurements with gas proportional instrumentation the effective source to detector geometry is representative of the calibrated geometries listed in Table 4.2 "Source to Detector Distance Effects, on Instrument Efficiencies for a- 03 Emitters".

- Corrections for temperature and pressure are not substantial.

In this example, the value for 8i is 0.2413 as depicted in Table 4.2 "Source to Detector Distance Effects on Instrument Efficiencies for a-P3 Emitters". The &s value of 0.5 is chosen refer to Table 4.3 "Source Efficiencies as listed in ISO 7503-1". Therefore the total efficiency for this condition becomes stot = si x es = 0.2413 x 0.5 = 0.121 or 12.1%.

7.0

==

Conclusion:==

Field conditions may significantly influence the usefulness of a survey instrument. When applying the instrument and source efficiencies in MDC calculations, field conditions must be considered. Tables have been constructed to assist in the selection of appropriate instrument and source efficiencies. Table 4.2 "Source to Detector Distance Effects on Instrument Efficiencies for a-0l Emitters" lists instrument efficiencies (si) at various source to detector distances for alpha and beta emitters. The appropriate ei value should be applied, accounting for the field condition, i.e. the relation between the detector and the surface to be measured.

Source efficiencies shall be selected from Table 4.3 "Source Efficiencies as listed in ISO 7503-1". This table lists conservative es values that correct for self-absorption and attenuation of surface activity.

Table 5.1 "Energy Response and Efficiency for Photon Emitting Isotopes" lists Ei values that apply to scanning MDC calculations. The MicroshieldTM model code was used to determine instrument efficiency assuming contamination conditions and detector geometry cited in section 5.6.2.4.4 "MDCs for Gamma Scans of Land Areas" of the License Termination Plan [8.6].

Detector and source conditions equivalent to those modeled herein may directly apply to the results of this report.

YA-REPT-00-015-04 Rev. 0 Page 10 of 26

8.0 References 8.1 NUREG-1507, "Minimum Detectable Concentrations with Typical Radiation Survey Instruments for Various Contaminants and Field Conditions," 1998 8.2 ISO 7503-1, "Evaluation of Surface Contamination - Part I: Beta Emitters and Alpha Emitters," 1988-08-01.

8.3 ISO 8769, "Reference Sources for the Calibration of Surface Contamination Monitors-Beta-emitters (maximum beta energy greater 0.15MeV) and Alpha-emitters," 1988-06-15.

8.4 "Radiological Health Handbook," Revised Edition 1970.

8.5 DP-8534, "Operation and source Checks of Portable Friskers".

8.6 Yankee Nuclear Plant Site License Termination Plan, Rev.0, November 2003.

YA-REPT-00-0 15-04 Rev. 0 Page 11 of 26

0 : !ii APPENDIX A MicroShield v6.02 (6.02-00253)

Page DOS File Run Date Run Time Duration

1

SPA3-EFF-Co-60.ms6 September 10, 2004 8:56:50 AM.

00:00:00 File Ref Date By Checked Case

Title:

SPA3-EFF-Co-60

==

Description:==

SPA-3 Soil scan - 28 cm radius lpCi/cm3 Co-60 Geometry: 8 - Cylinder Volume - End Shields Height Radius Source Dimensions:

15.0 cm 28.0 cm (5.9 in)

(11.0 in)

Dose Points Y

V A

1. 1 X

0 cm 25 cm 0.0 in 9.8 In Shields Dimension Material 3,69e+04 cm 3 Concrete Air z

0 cm 0.0 in Density 1.6 0.00122 Shield N So u rce Air Gap Nuclide Co-60 Source Input: Grouping Method - Actual Photon Energies curies becquerels pCI/cm3 3.6945e-008 1.3670e+003 1.00OOe-006 Buildup : The material reference is - Source Integration Parameters Bq/ cm 3 3.7000e-002 Radial Circumferential Y Direction (axial) 20 10 10 Energy Activity MeV Photons/sec 0.6938 1.1732 1.3325 Totals 2.230e-01 1.367e+03 1.367e+03 2.734e+03 Fluence Rate MeV/cm2 /sec No Buildup 9.05Se-06 1.098e-01 1.293e-01 2.391e-01 Results Fluence Rate MeV/cm2/sec With Buildup 1.590e-05 1.669e-01 1.904e-01 3.573e-01 Exposure Rate mR/hr No Buildup 1.748e-08 1.962e-04 2.244e-04 4.205e-04 Exposure Rate mR/hr With Buildup 3.070e-08 2.982e-04 3.303e-04 6.286e-04 YA-REPT-00-015-04 Rev. 0 Page 12 of 26

APPENDIX B YA-REPT-00-015-04 Rev. 0 Page 13 of 26

APPENDIX C MicroShield v6.02 (6.02-00253)

Page DOS File Run Date Run Time Duration

1

SPA3-EFF-Nb-94.ms6 September 16, 2004 3:22:38 PM 00:00:00 File Ref Date By Checked Case

Title:

SPA3-EFF-Nb-94

==

Description:==

SPA-3 Soil scan - 28 cm radius lpCi/cm3 Nb-94 Geometry: 8 - Cylinder Volume - End Shields Source Dimensions:

Height 15.0 cm Radius 28.0 cm (5.9 in)

(11.0 in)

Dose Points y

A

1. 1 X

0 cm 0.0 in Y

25 cm 9.8 in Material Concrete Air z

0cm 0.0 in Density 1.6 0.00122 Shield N Source Air Gap Shields Dimension 3.69e+04 cm 3 Nuclide Nb-94 Source Input: Grouping Method - Actual Photon Energies curies becquerels izCi/cm 3 3.6945e-008 1.3670e+003 1.00OOe-006 Buildup : The material reference is - Source Integration Parameters Bq/cm3 3.7000e-002 Radial Circumferential Y Direction (axial) 20 10 10 Energy Activity MeV Photons/sec 0.0023 0.0174 0,0175 0.0196 0.7026 0.8711 Totals 9.067e-02 4.834e-01 9.260e-01 2.720e-01 1.367e+03 1.367e+03 2.736e+03 Fluence Rate MeV/cmz/sec No Buildup 1.391e-10 8.762e-09 1.719e-08 7.924e-09 5.643e-02 7.464e-02 1.311e-01 Results Fluence Rate MeV/cm 2/sec With Buildup 1.430e-10 9.129e-09 1.792e-08 8.356e-09 9.872e-02 1.228e-01 2.216e-01 Exposure Rate mR/hr No Buildup 1.86le-10 4.729e-10 9.104e-10 2.925e-10 1.088e-04 1.405e-04 2.493e-04 Exposure Rate mR/hr With Buildup 1.913e-10 4.927e-10 9.491e-10 3.085e-10 1.904e-04 2.312e-04 4.216e-04 YA-REPT-00-015-04 Rev. 0 Page 14 of 26

APPENDIX D YA-REPT-00-015-04 Rev. 0 Page 15 of 26

APPENDIX E MicroShield v6.02 (6.02-00253)

Page DOS File Run Date Run Time Duration

1

SPA3-EFF-Ag-108mr.ms6 September 16, 2004 3:30:40 PM 00:00:00 File Ref Date By Checked Case

Title:

SPA3-EFF-Ag-108m

==

Description:==

SPA-3 Soil scan - 28 cm radius lpCi/cm3 Ag-108m Geometry: 8 - Cylinder Volume - End Shields Height Radius Source Dimensions:

15.0 cm 28.0 cm (5.9 in)

(11.0 in)

Dose Points A

1. 1 X

0 cm 0.0 in Shields Dimension 3.69e+04 cm 3 Y

25 cm 9.8 in Material Concrete Air z

0 cm 0.0 in Density 1.6 0.00122 Shield N Source Air Gap Nuclide Ag-108m Source Input: Grouping Method - Actual Photon Energies curies becquerels pCi/cm3 3.6945e-008 1.3670e+003 1.00OOe-006 Buildup : The material reference is - Source Integration Parameters Bq/cm3 3.7000e-002 Radial Circumferential Y Direction (axial) 20 10 10 Energy MeV 0.0028 0.003 0.021 0.0212 0.022 0.0222 0.0238 0.0249 0.0304 0.0792 0.4339 0.6144 0.7229 Totals Activity Photons/sec 6.580e+01 7.853e+00 2.491e+02 4.727e+02 7.024e+00 1.330e+01 1.501e+02 4.289e+00 2.902e-04 9.687e+01 1.229e+03 1.236e+03 1.237e+03 4.768e+03 Fluence Rate MeV/cm 2/sec No Buildup 1.252e-07 1.568e-08 9.534e-06 1.862e-05 3.202e-07 6.251e-07 9.273e-06 3.145e-07 4.43le-11 2.008e-04 2.705e-02 4.282e-02 5.300e-02 1.231e-01 Results Fluence Rate MeV/cm2/sec With Buildup 1.287e-07 1.612e-08 1.015e-05 1.985e-05 3.434e-07 6.714e-07 1.010e-05 3.464e-07 5.248e-11 4.802e-04 5.514e-02 7.808e-02

9. 194e-02 2.257e-01 Exposure Rate mR/hr No Buildup 1.351e-07 1.612e-08 2.824e-07 5.389e-07 8.233e-09 1.568e-08 1.863e-07 5.492e-09 4.230e-13 3.190e-07 5.294e-05 8.347e-05 1.019e-04 2.398e-04 Exposure Rate mR/hr With Buildup 1.388e-07 1.657e-0B 3.007e-07 5.744e-07 8.831e-09 1.685e-08 2.029e-07 6.050e-09 5.010e-13 7.629e-07 1.079e-04 1.522e-04 1.768e-04 4.389e-04 YA-REPT-00-015-04 Rev. 0 Page 16 of 26

APPENDIX F YA-REPT-00-015-04 Rev. 0 Page 17 of 26

Page DOS File Run Date Run Time Duration

1

SPA3-EFF-Sb-125.ms6

September 16. 2004

3:34:07 PM

00:00:00 APPENDIX G MicroShield v6.02 (6.02-00253)

File Ref Date By Checked Case

Title:

SPA3-EFF-Sb-125

==

Description:==

SPA-3 Soil scan - 28 cm radius I pCi/cm3 Sb-125 Geometry: 8 - Cylinder Volume - End Shields Height Radius Source Dimensions:

15.0 cm 28.0 cm (5.9 in)

(1l.Oin)

A NI Dose Points X

0cm 0.0 in Shields Dimension 3.69e+04 cm3 Y

25 cm 9.8 in Material Concrete Air z

0.0 in Shield N Source Air Gap Density 1.6 0.00122 Nudide Sb-125 curies 3.6945e-008 Source Input : Grouping Method - Aetual Photon Energies Occquerds, pCi/cm.

1.3670e+003 I.0000e-006 Bq/cms 3.7000e.002 Buildup: The material reference is - Source Integration Parameters Radial Circumferential Y Direction (axial)

Energy MeV 0.0038 0.0272 0.0275 0.031 0.0355 0.117 0.159 0.1726 0.1763 0.2041 0.2081 0.2279 0.32 I 0.3804 0.408 0.4279 0.4435 0.4634 0.6006 0.6066 0.6359 0.6714 Totals Activity Photons/see 6.762e+0 I 1.748e+02 3.262e+02

1. 132e+02 5.693e+01 3.568e+00 9.53le-01 2.478e+00 9.422e+01 4.41 Oe+00 3.324e-i003 1.796e+00 5.701 e+00 2.045e+0 I 2.486e+00 4.009e+02 4.130e+-00 1.415et+02 2.430eI-02 6.864e+0 I 1.548e+02 2.47&e+OI 1.916Ge+03 Fluence Rate M Vicmnt/sec No Buildup 1.708e-07 1.795e-05 3.453e-05 1.857e-05 1.492e.05 1.380t-05 5.634e-06 1.634e-05 6.392e-04 3.630e-05 2.805e-05 1.708e-05 8.474e-05 3.792Ze-04 5.05 le-05 8.668e-03 9.356e-05 3.395e-03 8.1 74e-03 2.340e.03 5.609e-03 9.640e-04 3.060e-02 Results Fluence Rate MeV/cma/see With Buildup 1.756e-07 2.020e-05 3.922e-05 2.221 e-05 1.91 8e-05 3.71 Se-05 1.499e-05 4.295e-05 1.674e-03 9.230e-05 7.103e-05 4.229e-05 1.899e-04 8.052e-04 1.049e-04 1.774e-02 1.894e-04 6.78 le-03 1.501e-02 4.283e-03 1.012e-02 1.71 Oe-03 5.901e-02 20 10 10 Exposure Rate mR/hr No Buildup 1.388e-07 2.376e-07 4.461 e-07 1.670e-07 9.090e-08 2.146e-08 9.416e-09 2.787e-08 1.096c-06 6.435e-08 4.994e-08 3.098e-08 1.620e-07 7.364e-07 9.853e.08 1.695e-05 1.832e-07 6.658e-06 1.595e-05 4.564e-06 1.09le-05 1.867e-06 6.046e-05 Exposure Rate mR/hr With Buildup 1.427e-07 2.689e-07 5.067e-07 1.997e-07 1.169e-07 5.778e-08 2.505e-08 7.326e-08 2.870e-06 1.636c-07 1.264e-07 7.670e-08 3.632e-07 1.564e-06 2.047e-07 3.470e-05 3.709e-07 1.330e-05 2.930e-05 8.355c-06 1.967e-05 3.31 Ie-06 1.158e-04 YA-REPT-00-015-04 Rev. 0 Page 18 of 26

APPENDIX H YA-REPT-00-015-04 Rev. 0 Page 19 of 26

APPENDIX I MicroShield v6.02 (6.02-00253)

Page DOS File Run Date Run Time Duration

1

SPA3-EFF-Cs-134.ms6 September 16, 2004 3:39:09 PM 00:00:00 File Ref Date By Checked Case

Title:

SPA3-EFF-Cs-134

==

Description:==

SPA-3 Soil scan - 28 cm radius lpCi/cm3 Cs-134 Geometry: 8 - Cylinder Volume - End Shields Height Radius A

1. 1 Source Dimensions:

15.0 cm 28.0 cm V

Dose Points Y

(5.9 in)

(11.0 in) z 0 cm 0.0 in X

0 cm 0.0 in 25 cm 9.8 In Ix Shields Shield N Source Air Gap Dimension 3.69e+04 cm 3 Material Concrete Air Density 1.6 0.00122 Nuclide Cs-134 Source Input: Grouping Method - Actual Photon Energies curies becquerels pCi/cm 3 3.6945e-008 1.3670e+003 1.00OOe-006 Buildup : The material reference is - Source Integration Parameters Bq/cm3 3.7000e-002 Radial Circumferential Y Direction (axial) 20 10 10 Energy MeV 0.0045 0.0318 0.0322 0.0364 0.2769 0.4753 0.5632 0.5693 0.6047 0.7958 0.8019 1.0386 1.1679 1.3652 Totals Activity Photons/sec 1.222e+00 2.931e+00 5.407e+00 1.968e+00 4.839e-01 1.996e+01 1.146e+02 2.109e+02 1.334e+03 1.167e+03 1.193e+02 1.367e+01 2.461e+01 4.156e+01 3.058e+03 Fluence Rate MeV/cm 2/sec No Buildup 3.658e-09 5.271e-07 1.014e-06 5.611e-07 5.931e-06 4.950e-04 3.545e-03 6.619e-03 4.529e-02 5.668e-02 5.852e-03 9.377e-04 1.964e-03 4.055e-03 1.254e-01 Results Fluence Rate MeV/cm 2/sec With Buildup 3.760e-09 6.386e-07 1.236e-06 7.321e-07 1.391e-05 9.808e-04 6.648e-03 1.237e-02 8.300e-02 9.564e-02 9.853e-03 1.472e-03 2.990e-03 5.936e-03 2.189e-01 Exposure Rate mR/hr No Buildup 2.507e-09 4.391e-09 8.157e-09 3.188e-09 1.113e-08 9.712e-07 6.940e-06 1.295e-05 8.836e-05 1.079e-04 1.113e-05 1.717e-06 3.514e-06 6.993e-06 2.405e-04 Exposure Rate mR/hr With Buildup 2.577e-09 5.320e-09 9.943e-09 4.160e-09 2.610e-08 1.924e-06 1.302e-05 2.421e-05 1.619e-04 1.820e-04 1.874e-05 2.696e-06 5.349e-06 1.024e-05 4.202e-04 YA-REPT-00-015-04 Rev. 0 Page 20 of 26

APP'FNDTX Jf YA-REPT-00-015-04 Rev. 0 Page 21 of 26

APPENDIX K MicroShield V6.02 (6.02-00253)

Page DOS File Run Date Run Time Duration

1

SPA3-EFF-Cs-137.ms6 September 10, 2004 8:52:18 AM 00:00:00 File Ref Date By Checked Case

Title:

SPA3-EFF-Cs-137

==

Description:==

SPA-3 Soil scan - 28 cm radius lpCi/cm3 Cs-137 and Daughters Geometry: 8 - Cylinder Volume - End Shields Height Radius A

1. 1 Source Dimensions:

15.0 cm 28.0 cm (5.9 in)

(11.0 in)

Dose Points X

0 cm 0.0 in Shields Dimension 3.69e+04 cm 3 Y

25 cm 9.8 in Material Concrete Air z

0 cm 0.0 in Density 1.6 0.00122 Shield N Source Air Gap Nuclide Ba-137m Cs-137 Source Input: Grouping Method - Actual Photon Energies curies becquerels IjCi/cm 3 3.4950e-008 1.2932e+003 9.4600e-007 3.6945e-008 1.3670e+003 1.00OOe-006 Buildup : The material reference Is - Source Integration Parameters Bq/cm3 3.5002e-002 3.7000e-002 Radial Circumferential Y Direction (axial) 20 10 10 Energy Activity MeV Photons/sec 0.0045 0.0318 0.0322 0.0364 0.6616 Totals 1.342e+01 2.677e+01 4.939e+01 1.797e+01 1.164e+03 1.271e+03 Fluence Rate MeV/cm 2/sec No Buildup 4.020e-08 4.815e-06 9.260e-06 5.126e-06 4.442e-02 4.444e-02 Results Fluence Rate MeV/cm 2/sec With Buildup 4.133e-08 5.834e-06 1.129e-05 6.688e-06 7.913e-02 7.915e-02 Exposure Rate mR/hr No Buildup 2.755e-08 4.011e-08 7.452e-08 2.912e-08 8.61le-05 8.628e-05 Exposure Rate mR/hr With Buildup 2.833e-08 4.860e-08 9.084e-08 3.800e-08 1.534e-04 1.536e-04 YA-REPT-00-015-04 Rev. 0 Page 22 of 26

APPENDIX L YA-REPT-00-015-04 Rev. 0 Page 23 of 26

APPENDIX M MicroShield v6.02 (6.02-00253)

Page DOS File Run Date Run Time Duration

1

SPA3-EFF-Eu-152.ms6 October 7, 2004 11:25:11 AM 00:00:00 File Ref

ýDate

'Uv Checked Case

Title:

SPA-3-EFF-Eu-152 Description; SPA-3 Soil scan - 28cm radius 1 PCl/cm3 Eu-152 Geometry: 8 - Cylinder Volume - End Shields Source Dimensions:

Height 15.0 cm (5.9 In)

Radius 28.0 cm (11.0 In) o -

Dose Points A

X V

z Y

.2

1. 1 0 cm 0.0 In 25 cm 9.8 In 0 cm 0.0 In Shields Shield N Dimension Material Density Source 3.69e+04 cm 3 Concrete 1.6 Air Gap Air 0.00122 Nuclide Eu-152 curies 3.6945e-008 Source Input: Grouping. Method - Standard Indices Number of Groups :25 Lower Energy Cutoff z 0.015 Photons < 0.015 : Included Library: Grove becquerels Mci/cm 3

1.3670e+003 1.00O0e-006 Buildup : The material reference is - Source Integration Parameters Sq/cm,

3. 7 000e-002 Radial YCircumferential Y Direction (axial)

Energy Activity Fluence Rate MeV Photons/sei MeV/cm2 /sec No Buildup 0.015 0.04 0.05 0.1 0.2 0.3 0.4 0.5 0.6 0.8 1.0 1.5 Totals 2.077e+02 8.088e+02 2.022e+02 3.887e+02 1.024e+02 3.696e+02 8.590e+01 7.711e+00 5.797e+01 2.434e+02 5.849e+02 3.171e+02 3.376e+03 2.087e-06 3.13le-04 1.507e-04 1.189e-03 8.207e-04 5.029e-03 1.70le-03 2.043e-04 1.948e-03 1.190e-02 3.820e-02 3.490e-02 9.635e-02 20 10 10 Results Exposure Fluence Rate Rate MeV/cm2/sec mR/hr With Buildup No Buildup 2.146e-06 1.790e-07 4.331e-04 1.385e-06 2.467e-04 4.014e-07 3.118e-03 1.819e-06 2.097e-03 1.448e-06 1.151e-02 9.540e-06 3.555e-03 3.314e-06 3.984e-04 4.010e-07 3.579e-03 3.802e-06 2.005e-02 2.263e-05 6.058e-02 7.042e-05 4,999e-02 5.871e-05 1.556e-01 1.740e-04 Exposure Rate mR/hr With Buildup 1.841e-07 1.916e-06 6.572e-07 4.770e-06 3.700e-06 2.184e-05 6.926e-06 7.819e-07 6.985e-06 3.813e-05 1.117e-04 8.41le-05 2.817e-04 YA-REPT-00-015-04 Rev. 0 Page 24 of 26

APPENDIX N YA-REPT-00-015-04 Rev. 0 Page 25 of 26

APPENDIX 0 Calculated Energy Response (Eberline.Instruments)

CPMImR/h 100000000 I

mm I I I I I 11644.O-4-4 I

LiiIEI~~EEI5~UEEE~IJ i nnnnnnrn-a w

E E_

p-,.-p-q 4-*-*-

I I

'S' ilflllf-II

• I.

x

-L w-i,.i11i1 i

J ~i iL

-4 100000 0 I00 ENERGY 1000 (kev) 10000 YA-REPT-00-015-04 Rev. 0 Page 26 of 26

ALARA Analysis Worksheet Survey Area: SVC-01 Survey Unit: 18 A. Estimation of Total Cost (CostT)

1. Cost of performing remediation work (CostR) (assume 3-staff crew for 1 day@average $60 per hour; cost

$ 1800 for heavy equipment not included)

2. Cost of waste disposal (CostwD) = (2.a) * (2.b)

$ 670

a. estimated waste volume: 1 m3

b. cost of waste disposal: $670/M3

3. Cost of workplace accident (CostAcc) = $3,000,000 person-' -4.2x10 8 W-' (3.a)

$ 3.78

a. time to perform remediation action: 30 person-hours

4. Cost of traffic fatality (COStTF) =

{$3,000,000

• 3.8x108 km-' * (2.a) - (4.a)}/(4.b)

$ 34.37

a. total distance traveled per shipment: 4100 km

b. waste volume per shipment: 13.6 M3, if unknown, use 13.6m3 as a default value

5. Cost of worker dose (COstwDose) = $2,000 per person-rem -(5.a) -(5.b)

$0

a. worker TEDE:

rem/h

b. remediation exposure time person-hour CostT

$2508 B. Survey Unit Radiological Information Radionuclide Average Concentration Relative Fractiona Half-Life (y)

Decay Constantb (y-l)

1. Co-60

a. 6622 dpm/lOOcm 2

b. I

c. 5.271

d. 0.13

2.

a.

b.

c.

d.

3.

a.

b.

c.

d.

4.

a.

b.

C.

d.

5.

a.

b.

c.

d.

6.

a.

b.

c.

d.

7.

a.

b.

c.

d.

8.

a.

b.

c.

d.

Total Concentration:

a Relative fraction = average concentration divided by the total concentration.

b Decay constant = 0.693 divided by half-life.

DPF-8867.1 Page 1 of 3

C. Calculation of ALARA Action Level (AL)

1. Removable fraction for remediation action being evaluated: 1.0

2. Monetary discount rate: 0.03 y'

3. Number of years over which the collective dose is calculated: 1000 y

4. Population density for the critical group: 0.0004 people/m 2

5. Area being evaluated: 100 m2

6. AL for each radionuclide-of-interest:

a. AL = {CostT/($2 00 0 " C.4" 0.025 C.1 C.5)}

{(C.2 + B.l.d)/(l-e(C2+Bld) C. 3}

{B.l.b} =

b. AL = {CostT/($2 0 0 0 " C.4" 0.025 C.1 C.5)} {(C.2 + B.2.d)/(1-e-Cc2++/-B2"'d)'C.3} {B.2.b} =

c. AL = {CostT/($2 0 00 -C.4A 0.025 C.1 C.5)} {(C.2 + B. 3.d)/(l-e-(C2+B3 d)c3}

{B.3.b} =

d. AL = {CostT/($2000" C.4 0025 C.1 I C.5)}

{(C.2 + B.4.d)/(l1-e(c 2+B4 d)C3}.

{B.4.b} =

e. AL = {CostT/($2000" C.4 0025 C.1 C.5)} - {(C.2 + B.5.d)/(l-e-(C2+B5d)C 3}. {B.5.b} =

f. AL = {CostT/($2000 C.4A 0.025-C.1

• C.5))

{(C.2 + B.6.d)/(1-e"(c2+B6 d)c 3} )

{B.6.b} =

g. AL = {CostT/($2000 C.4 *0.025 C.I - C.5)}

f{(C.2 + B.7.d)/(1-e"(C2+B7d)C 3}. {B.7.b} =

h. AL = {CostT/($2000 C.4 0.025 C.1

• C.5)}

f{(C.2 + B.8.d)/(l-e"(C'2+B'Sd)C. 3} {B.8.b} =

7.............................................................................. Sum of ALs (= ALARA AL) =

1356 1356 D. ALARA Evaluation Radionuclide DCGL DCGL Fractiona

1. Co-60 a 6622 dpm/1OOcm 2

b. (B.l.a)/(D.l.a) = 1.0

2.

a.

b. (B.2.a)/(D.3.a)=

3.

a.

b. (B.3.a)/(D.4.a) =

4.

a.

b. (B.4.a)/(D.5.a) =

5.

a.

b. (B.5.a)/(D.6.a) =

6.

a.

b. (B.7.a)/(D.7.a) =

7.

a.

b. (B.8.a)/(D.8.a) =

8.

a.

b. (B.9.a)/(D.9.a) =

9........................................................................... Sum of D CG L Fractions = 1.0 8 DCGL fraction = average residual concentration in survey unit (from Section B) divided by the DCGL.

DPF-8867.1 Page 2 of 3

10. Comparison of the sum of the DCGL fractions (D.9) to ALARA AL (C.7):

Check one:

Sum of the DCGL Fractions < ALARA AL V

Sum of the DCGL Fractions > ALARA AL

12. Decision Criteria: If the sum of the DCGL fractions < AL, then additional remediation is not cost beneficial. If the sum of the DCGL fractions > AL, then additional remediation is cost beneficial.

Check one:

Additional remediation IS NOT cost beneficial V

Additional remediation IS cost beneficial __

Prepared by 9-

$7 rFSS Radiological Engineer Date

//-*---

Date Reviewed by

)C-S 4

/L"I FSS Project Manager DPF-8867. I Page 3 of 3

Use Of In-Situ Gamma Spectrum Analysis To Perform Elevated Measurement Comparisons In Support Of Final Status Surveys YA-REPT-00-018-05 Approvals (Print & Sign Name)

Preparer: Greg Astrauckas/ !,

Preparer: Gordon Madison, C Reviewer: Jim Hummer, CHP/!

Approver (FSS Manager):

Dann Smith, CHP/

Date:

Date:

Date: I V/t '-/

0g-Date:

Rev. 0

YA-REPT-00-018-05 Rev. 0 Technical Report YA-REPT-00-018-05, Rev. 0 Use Of In-Situ Gamma Spectrum Analysis To Perform Elevated Measurement Comparisons In Support Of Final Status Surveys TABLE OF CONTENTS 1.0 Report............................................................................................................

2 1.1 Introduction...........................................................................................

2 1.2 Discussion..............................................................................................

2 1.2.1 Detector Description...................................................................

2 1.2.2 Traditional Approach................................................................

.3 1.2.3 Innovative Approach...................................................................

4 1.2.4 Investigation Level......................................................................

4 1.2.5 Detector Sensitivity...................................................................

8 1.2.6 Area Coverage............................................................................

8 1.2.7 Moisture Content in the Soil Matrix...........................................

9 1.2.8 Discrete Particles in the Soil Matrix........................................

10 1.2.9 Procedures and Guidance Documents.....................................

10 1.2.10 Environmental Background.......................................................

11 1.2.11 Quality Control..........................................................................

11 1.2.12 Data Collection.......................................................................

12 1.2.13 Efficiency Calibration..............................................................

13 1.2.14 Data Management.....................................................................

13 1.3 Conclusions/Recommendations............................................................

14 1.4 References..............................................................................................

14 Attachments, ISOCS Detector System Photos....................................................

15, Field-Of-View Characterization.....................................................

16, Typical Grid Pattern For In-Situ Gamma Spectroscopy.................

18 YA-REPT-00-018-05 Rev. 0 1.0 REPORT 1.1 Introduction The ISOCS In-Situ Gamma Spectrum detector system manufactured by Canberra Industries is being employed to perform elevated measurement comparison (EMC) surveys in support of the Final Status Surveys at Yankee Atomic's Yankee Rowe facility. This system uses an HPGe detector and specialized efficiency calibration software designed to perform in-situ gamma-spectroscopy assays. The ISOCS system will primarily be employed to evaluate survey units for elevated measurement comparisons. The ISOCS system can obtain a static measurement at a fixed distance from a pre-determined location. Count times can be tailored to achieve required detection sensitivities. Gamma spectroscopy readily distinguishes background activity from plant-related licensed radioactivity. This attribute is particularly beneficial where natural radioactivity introduces significant investigation survey efforts. Additionally, background subtraction or collimation can be employed where background influences are problematic due to the presence of stored spent fuel (ISFSI).

This technical report is intended to outline the technical approach associated with the use of ISOCS for implementing a MARSSIM-based Final Status Survey with respect to scanning surveys for elevated measurement comparisons for both open land areas and building surfaces. While the examples and discussions in this report primarily address open land areas, the same approach and methodology will be applied when deriving investigation levels, grid spacing and measurement spacing for evaluating building surfaces.

Validation of the ISOCS software is beyond the scope of this technical report.

Canberra Industries has performed extensive testing and validation on both the MCNP-based detector characterization process and the ISOCS calibration algorithms associated with the calibration software. The full MCNP method has been shown to be accurate to within 5% typically. ISOCS results have been compared to both full MCNP and to 119 different radioactive calibration sources. In general, ISOCS is accurate to within 4-5% at high energies and 7-11% at 1 standard deviation for low energies. Additionally, the ISOCS technology has been previously qualified in Yankee Atomic Technical Report YA-REPT-00-022-04, "Use Of Gamma Spectrum Analysis To Evaluate Bulk Materials For Compliance With License Termination Criteria."

1.2 Discussion 1.2.1 Detector Description Two ISOCS-characterized HPGe detectors manufactured by Canberra Industries have been procured. Each detector is a reverse-electrode HPGe YA-REPT-00-018-05 Rev. 0 detector rated at 50% efficiency (relative to a Nal detector). Resolution for these detectors is 2.2 keV @ 1332 keV. As the project progresses, other ISOCS detectors (e.g. standard electrode coaxial), if available, may be used to increase productivity. The key element regarding the use of other types of ISOCS0 detectors is that specific efficiency calibrations will be developed to account for each detector's unique characteristics.

The HIPGe detector is mounted on a bracket designed to hold the detector /

cryostat assembly and associated collimators. This bracket may be mounted in a wheeled cart or in a cage-like frame. Both the wheeled cart and frame permit the detector to be oriented (pointed) over a full range from a horizontal to vertical position. The frame's design allows the detector to be suspended above the ground. Photographs of the frame-mounted system are presented in Attachment 1. During evaluations of Classl areas for elevated radioactivity, the detector will generally be outfitted with the 90-degree collimator. Suspending the detector at 2 meters above the target surface yields a nominal field-of-view of 12.6 M2.

The InSpector (MCA) unit that drives the signal chain and the laptop computer that runs the acquisition software (Genie-2000) are mounted either in the frame or on the wheeled cart. These components are battery powered.

Back-up power supplies (inverter or UPS) are available to support the duty cycle. A wireless network has been installed at the site so that the laptop computers used to run the systems can be completely controlled from any workstation at the facility. This configuration also enables the saving of data files directly to a centralized file server. Radio communication will be used to coordinate system operation.

1.2.2 Traditional Approach With respect to Class 1 Survey Units, small areas of elevated activity are evaluated via the performance of scan surveys. The size of the potential area of elevated activity affects the DCGLEMc and is typically determined by that area bounded by the grid points used for fixed measurements. This area in turn dictates the area factor(s) used for deriving the associated DCGLEMC.

These scan surveys are traditionally conducted with hand-held field instruments that have a detection sensitivity sufficiently low to identify areas of localized activity above the DCGLEMc. Occasionally, the detection sensitivity of these instruments is greater than the DCGLEMC. In order to increase the DCGLEMc to the point where hand-held instrumentation can be reasonably employed, the survey design is augmented to require additional fixed-point measurements. The effect of these additional measurement points is to tighten the fixed measurement grid spacing, thus reducing the area applied to deriving the DCGLEMc and increasing the detection sensitivity criteria.

YA-REPT-00-018-05 Rev. 0 Background influences (from the ISFSI) and natural terrestrial sources further impact the sensitivity of these instruments. To address these impacts, the fixed-point grid spacing would again need to be reduced (requiring even more samples) in order to increase the DCGLEMc to the point where hand-held instrumentation can be used. Generally, the collection of additional fixed measurements (i.e. samples) increases project costs.

Survey designs for Class 2 and Class 3 survey units are not driven by the elevated measurement comparison because areas of elevated activity are not expected. In Class 2 areas, any indication of activity above the DCGLw requires further investigation. Similarly, in Class 3 areas, any positive indication of licensed radioactivity also requires further investigation.

Because the DCGLEMc is not applicable to Class 2 or Class 3 areas, adjustments to grid spacing do not occur. However, the increased field-of-view associated with the in-situ gamma spectroscopy system improves the efficiency of the survey's implementation.

1.2.3 Innovative Approach In-situ assays allow fixed-point grid spacing to be uncoupled from the derivation of applicable investigation levels. In contrast to the traditional approach where the DCGLEMc (based on grid size) determines both investigation levels and detection sensitivities, the use of this technology provides two independent dynamics as follows:

" Detection sensitivity is determined by the DCGLEMc associated with the (optimal) fixed-point grid spacing.

" Investigation levels are based on the detector's field-of-view and adjusted for the smallest area of concern (i.e. 1 mn 2).

1.2.4 Investigation Level Development of the investigation (action) levels applied to in-situ assay results is a departure from the traditional approach for implementing a MARSS]M survey. Examples are provided for both open land areas (i.e. soil) and for building surfaces, however the approach for both is identical.

To support the use of in-situ spectroscopy to evaluate areas of elevated activity the HPGe detector's field-of-view was characterized. Attachment 2 presents data from the field-of-view characterization for a detector configured with a 90-degree collimator positioned 2 meters from the target surface.

Alternate configurations will be evaluated in a similar manner before being employed. As exhibited in Attachment 2, when the detector is positioned at 2 meters above the target surface the field-of-view has a radius of at least 2.3 YA-REPT-00-018-05 Rev. 0 meters. This value was rounded down to 2.0 meters for implementation purposes, introducing a conservative bias (approximately.9%) in reported results. The example provided in this technical report assumes a 2-meter source-to-detector distance, yielding a nominal field-of-view surface area of 12.6 in2.

Occasionally, alternate source-to-detector distances (using the 90-degree collimator) may be employed, particularly in a characterization or investigation capacity. In such cases, the detector's field-of-view will be calculated by setting the radius equal to the source-to-detector distance, thereby maintaining the conservative attribute previously described. If alternative collimator configurations are used to perform elevated measurement comparisons, then specific evaluations will be documented in the form of a technical evaluation or similar. Associated investigation levels will be derived using the same approach and methodology outlined below in this section.

After the detector's field-of-view is determined, an appropriate investigation level is developed to account for a potential one-meter square area of elevated activity. DCGLEMc values for a one-square meter area are presented in Table 1.

TABLE 1, SOIL DCGLEMc FOR 1 m2 Soil Soil DCGLEMc DCGLw DCGLw Area Factor for I m2 (pCi/g)

(pCi/g) for 1 n2 (pCilg)

(NOTE 1)

(NOTE 2)

(NOTE 3)

(NOTE 4)

Co-60 3.8 1.4 11 15 Ag-108m 6.9 2.5 9.2 23 Cs-134 4.7 1.7 16 28 Cs-137 8.2 3.0 22 66 NOTE 1 - LTP Table 6-1 NOTE 2 - Adjusted to 8.73 mRem/yr NOTE 3 - LTP Appendix 6Q NOTE 4 - Soil DCGLw (adjusted to 8.73 mnRem/yr) for a 1 mr area The "n2DCGLEMc values listed in Table 1 do not account for a source positioned at the edge of the field-of-view. Therefore, the In2DCGLEMc values are adjusted via a correction factor. To develop this correction factor, a spectrum free of plant-related radioactivity was analyzed using two different efficiency calibrations (i.e. geometries). The first scenario assumes radioactivity uniformly distributed over the detector's 12.6 m2 field-of-view.

The second scenario assumes radioactivity localized over a 1 M2 situated at the edge of the detector's field-of-view. The resultant MDC values were compared to characterize the difference in detection efficiencies between the two scenarios. As expected, the condition with localized (1 M2) radioactivity at the edge of the detector's field-of-view yielded higher MDC values. The ratio between the reported MDC values for the two scenarios is used as a

• correction factor. This correction factor is referred to as the offset geometry YA-REPT-00-018-05 Rev.

adjustment factor. The investigation levels for soils presented in Table 2 were calculated as follows:

Nuclide Investigation Level (pCi/g) = (DCGLEMc)

• CF Where: DCGLEMc = (DCGLw or DCGLsuRR)

• AF(1 ml), and CF = Mean offset geometry adjustment factor TABLE 2, SOIL INVESTIGATION LEVEL DERIVATION INVESTIGATION MDC DCGLEMc LEVEL pCi/g MDC pCi/g RATIO for 1 m2 pCi/g (NOTE 1)

(NOTE 2)

(NOTE 3)

(NOTE 5)

(NOTE 6)

Co-60 0.121 1.86 0.0651 15 1.0 Ag-108m 0.184 2.82 0.0652 23 1.5 Cs-134 0.189 2.90 0.0652 28 1.8 Cs-137 0.182 2.78 0.0655 66 4.3 Offset Geometry Adjustment Factor 0.0653 (NOTE 4)

NOTE 1 - Assumed activity distributed over the 12.6 m2 field-of-view.

NOTE 2 - Efficiency calibration modeled for a I mn area situated (off-set) at the edge of the detector's field-of-view. The model assumes that all activity is distributed within the I mi.

NOTE 3 - Ratio = (12.6 m' MDC +1 mI MDC).

NOTE 4 - The mean value of the ratios is applied as the off-set geometry adjustment factor.

NOTE 5 - DCGLEMc values for I m' (from Table 1)

NOTE 6 - Investigation levels derived by applying of the off-set geometry adjustment factor (e.g. 0.0653) to the DCGLamc for a I mr area for each radionuclide.

With respect to building surfaces, the development of the investigation level is identical to that for soil surfaces. The one-meter square DCGLEMC for building surfaces are presented in Table 3.

TABLE 3, BUILDING SURFACE DCGLEMC FOR 1 m2 DCGLEMC Bldg DCGLw Bldg DCGLw Area Factor For I m2 (dpm/100m1)

(dpm/100cm2)

For 1 m2 (dpm/100cm')

(NOTE 1)

(NOTE 2)

OTE 3)

(NOTE 4)

Co-60 18,000 6,300 7.3 46,000 Ag-108m 25,000 8,700 7.2 62,600 Cs-134 29,000 10,000 7.4 74,000 Cs-137 63,000 22,000 7.6 167,000 NOTE I - LTP Table 6-1 NOTE 2 - Adjusted to 8.73 mRem/yr NOTE 3 - LTP Appendix 6S NOTE 4 - Building DCGLw (adjusted to 8.73 mRem/yr) for a 1 m2 area Using the same approach described for soils, a correction factor to account for efficiency differences due to geometry considerations is developed the one-meter square DCGLEMc. ISOCS efficiency calibrations for activity distributed over the detector's field-of-view and for activity within one-square meter located at the edge of the detector's field-of-view were developed. The MDC values for these two geometries were compared to characterize the difference in detection efficiencies. As expected, the condition with localized (1 mi2)

YA-REPT-00-018-05 Rev. 04 radioactivity at the edge of the detector's field-of-view yielded higher MDC values. The ratio between the reported MDC values for the two scenarios is used as the offset geometry adjustment factor. The MDC values, the associated ratios, and the derived investigation level for building surfaces are presented in Table 4.

TABLE 4, BUILDING SURFACE INVESTIGATION LEVEL DERIVATION BUILDING SURFACE 12.6 m2 I m2 DCGLEMc INVESTIGATION MDC MDC For 1 mI LEVEL (dpr/lOOcmna)

(dpm/l00cm')

RATIO (dpm/l00cm')

(dpmf OOcm2)

(NOTE 1)

(NOTE 2)

(NOTE 3)

(NOTE 5)

(NOTE 6)

Co-60 785 12,400 0.0633 46,000 2,900 Ag-108m 839 13,000 0.0645 62,600 3,900 Cs-134 900 14,200 0.0634 74,000 4,700 Cs-137 922 14,600 0.0632 167,000 10,600 Offset Geometry Adjustment Factor 0.0636 (NOTE 4)

NOTE I - Assumed activity distributed over the 12.6 m' field-of-view.

NOTE 2 - Efficiency calibration modeled for a I ml area situated (off-set) at the edge of the detector's field-of-view. The model assumes that all activity is distributed within the I M2.

NOTE 3 - Ratio = (12.6 m` MDC + I mn MDC).

NOTE 4 - The mean value of the ratios is applied as the off-set geometry adjustment factor.

NOTE 5 - DCGLEMc values for I m2 (from Table 3)

NOTE 6 - Investigation levels derived by applying of the off-set geometry adjustment factor (e.g. 0.0636) to the one-square meter DCGLEMc.

In summary, effective investigation levels for both open land areas (i.e. soils) and for building surfaces can be derived and applied to in-situ gamma spectroscopy results. Note the MDC values associated with the detector's field-of-view were well below the derived investigation levels.

The investigation levels presented in Table 2 and Table 4 do not address the use of surrogate DCGLs. Use of surrogate DCGLs will be addressed in Final Status Survey Plans, particularly where it is necessary to evaluate non-gamma emitting radionuclides on building surfaces. When surrogate DCGLs are employed, investigation levels will be developed on a case-by-case basis using the approach outlined in this document. Similarly, the offset geometry adjustment factor presented in Table 2 and Table 4 will vary for different geometries. Although unlikely, if different geometries are employed, this value will be determined on a case-by-case basis using the methodology reflected in Table 2 and will be documented in the applicable Final Status Survey Plan.

For both open land areas and for building surfaces, when an investigation level is encountered, investigatory protocols will be initiated to evaluate the presence of elevated activity and bound the region as necessary. Such evaluations may include both hand-held field instrumentation as well as the in-situ HPGe detector system. After investigation activities are completed, YA-REPT-00-018-05 Rev. 0 subsequent (follow-up) scanning evaluations will most likely be conducted using the in-situ gamma spectroscopy system.

1.2.5 Detector Sensitivity For Class 1 scan surveys, the minimum detectable concentration is governed by the DCGLEMc associated with the grid area used to locate fixed-point measurements. The system's count time can be controlled to achieve the required detection sensitivity. Therefore, the grid spacing for the fixed-point measurements can be optimized thus eliminating unnecessary increases to the number of fixed-point measurements while ensuring that elevated areas between fixed measurement locations can be identified and evaluated.

Based on preliminary work, it has been determined that a count time of 900 seconds will yield an acceptable sensitivity for many areas on the site. This count time provides MDC values well below the investigation levels presented in Table 2 and Table 4. Count times will be adjusted as necessary as survey unit-specific investigation levels are derived or where background conditions warrant to ensure that detection sensitivities are below the applicable investigation level. Since each assay report includes a report of the MDC values achieved during the assay, this information is considered technical support that required MDC values were met.

1.2.6 Area Coverage Based on the nominal 12.6 m2 field-of-view, a 3-meter spacing between each survey point will result in well over 100% of the survey unit to be evaluated for elevated activity. This spacing convention typically employs a grid pattern that is completely independent from the grid used to locate fixed-point measurements. An example of the grid pattern and spacing is presented in.

Alternate spacing conventions may be applied on a case-by-case basis. For instance, spacing may be decreased when problematic topographies are encountered. Note that decreased grid spacing in this context is not associated to the fixed-point measurements. Occasionally it may be necessary to position the detector at one meter or less from the target surface to evaluate unusual (e.g. curved) surfaces or to assist in bounding areas of elevated activity. In cases where it may be desirable to increase the field-of-view via collimator or source-to-detector distances, grid-spacing conventions (and applicable investigation levels) will be determined using the approach described in this document.

YA-REPT-00-018-05 Rev. 0 1.2.7 Moisture Content in the Soil Matrix hI-situ gamma spectroscopy of open land areas is inherently subject to various environmental variables not present in laboratory analyses. Most notably is the impact that water saturation has on assay results. This impact has two components. First, the total activity result for the assay is assigned over a larger, possibly non-radioactive mass introduced by the presence of water.

Secondly, water introduces a self-absorption factor.

The increase in sample mass due to the presence of water is addressed by the application of a massimetric efficiency developed by Canberra Industries.

Massimetric efficiency units are defined as [counts per second]/[gammas per second per gram of sample]. Mathematically, this is the product of traditional efficiency and the mass of the sample. When the efficiency is expressed this way, the efficiency asymptotically approaches a constant value as the sample becomes very large (e.g. infinite). Under these conditions changes in sample size, including mass variations from excess moisture, have little impact on the counting efficiency. However, the massimetric efficiency does not completely address attenuation characteristics associated with water in the soil matrix.

To evaluate the extent of self-absorption, (traditional) counting efficiencies were compared for two densities.

Based on empirical data associated with the monitoring wells, typical nominally dry in-situ soil is assigned a density of 1.7 g/cc. A density of 2.08 g/cc, obtained from a technical reference publication by Thomas J. Glover, represents saturated soil. A density of 2.08 g/cc accounts for a possible water content of 20%. A summary of this comparison is presented in Table 5.

TABLE 5, COUNTING EFFICIENCY COMPARISONS Efficiencies Deviation due to density keV 1.7 P/cc 2.08 atcc increase (excess moisture) 434 3.3 E-6 2.7 E-6

-18.7%

661.65 2.9 E-6 2.4 E-6

-17.5%

1173.22 2.5 E-6 2.1 E-6

-15.4%

1332.49 2.4 E-6 2.1 E-6

-14.8%

In cases when the soil is observed to contain more than "typical" amounts of water, potential under-reporting can be addressed in one of two manners. One way is to adjust the investigation level down by 20%. The second way is to reduce the sample mass by 20%. Either approach achieves the same objective: to introduce a conservative mechanism for triggering the investigation level where the presence of water may inhibit counting efficiency. The specific mechanism to be applied will be prescribed in implementing procedures.

YA-REPT-00-018-05 Rev. 0 The presence of standing water (or ice or snow) on the surface of the soil being assayed will be accounted for in customized efficiency calibrations applied during data analysis activities.

1.2.8 Discrete Particles in the Soil Matrix Discrete particles are not specifically addressed in the License Termination Plan. However, an evaluation was performed assuming all the activity in the detector's field-of-view, to a depth of 15 cm, was situated in a discrete point-source configuration. A concentration of 1.0 pCi/g (Co-60), corresponding to the investigation level presented in Table 2, correlates to a discrete point-source of approximately 3.2 pCi. This activity value is considered as the discrete particle of concern. Since the presence of any discrete particles will most likely be accompanied by distributed activity, the investigation level may provide an opportunity to detect discrete particles below 3.2 gCi.

Discrete particles exceeding this magnitude would readily be detected during characterization or investigation surveys. The MDCs associated with hand-held field instruments used for scan surveys are capable of detecting very small areas of elevated radioactivity that could be present in the form of discrete point sources. The minimum detectable particle activity for these scanning instruments and methods correspond to a small fraction of the TEDE limit provided in 10CFR20 subpart E. Note that the MDC values presented in Table 2 are significantly lower than those published in Table 5-4 of the License Termination Plan.

When the investigation level in a Class 1 area is observed, subsequent investigation surveys will be performed to include the use of hand-held detectors. The detection sensitivities of instruments used for these surveys have been previously addressed in the LTP. Furthermore, discrete point sources do not contribute to the uniformly distributed activity of the survey unit. It is not expected that such sources at this magnitude would impact a survey unit's ability to satisfy the applicable acceptance criteria.

Noting that Class 2 or Class 3 area survey designs do not employ elevated measurement comparisons, associated investigation levels are based on positive indications of licensed radioactivity above the DCGLw or above background. Because such areas are minimally impacted or disturbed, potential discrete particles would most likely be situated near the soil surface where detection efficiencies are highest.

1.2.9 Procedures And Guidance Documents General use of the portable ISOCS system is administrated by departmental implementing procedures that address the calibration and operation activities as well as analysis of the data. These procedures are listed as follows:

YA-REPT-00-018-05 Rev. 0 9 DP-8869, "In-Situ (ISOCS) Gamma Spectrum Assay System Calibration Procedure."

e DP-8871, "Operation Of The Canberra Portable ISOCS Assay System."

DP-8872, "ISOCS Post Acquisition Processing And Data Review."

Where the portable ISOCS system is used for Final Status Surveys, the applicable FSS Plan will address detector and collimator configurations, applicable (surrogated) investigation levels, MDC requirements, and appropriate Data Quality Objectives, as applicable.

A secondary application of the portable ISOCSO system is to assay surfaces or bulk materials for characterization or unconditional release evaluations. Use of the portable ISOCS system for miscellaneous evaluations will be administrated under a specific guidance document (e.g. Sample Plan, etc.).

Operating parameters such as physical configuration, efficiency calibrations, count times, and MDCs will be applied so as to meet the criteria in the associated controlling documents. Such documents will also address any unique technical issues associated with the application and may provide guidance beyond that of procedure AP-0052, "Radiation Protection Release of Materials, Equipment and Vehicles."

1.2.10 Environmental Backgrounds If background subtraction is used, an appropriate background spectrum will be collected and saved. Count times for environmental backgrounds should exceed the count time associated with the assay. In areas where the background radioactivity is particularly problematic (e.g. ISFSI), the background will be characterized to the point of identifying gradient(s) such that background subtractions are either appropriate or conservative.

Documentation regarding the collection and application of environmental backgrounds will be provided as a component of the final survey plan.

1.2.11 Quality Control Quality Control (QC) activities for the ISOCS system ensure that the energy calibration is valid and detector resolution is within specifications. A QC file will be set up for each detector system to track centroid position, FWHM, and activity. Quality Control counts will be performed on a shiftly basis prior to the system's use to verify that the system's energy calibration is valid. The Na-22 has a 1274.5 keV photon which will be the primary mechanism used for performance monitoring. If the energy calibration is found to be out of an acceptable tolerance (e.g. greater than +/-4 channels), then the amplifier gain may be adjusted and a follow-up QC count performed. If the detector's Aresolution is found to be above the factory specification, then an evaluation YA-REPT-00-018-05 0

• Rev. 0 will be performed to determine if the detector should be removed from service and/or if the data is impacted. Evaluations associated with QC counts shall be documented. Such documentation may be limited to a remark directly on the applicable QC report or in a logbook if the resolution does not render the system out of service. Otherwise the evaluation should be separately documented (e.g. Condition Report, etc.) so as to address the impact of any assay results obtained since the last acceptable QC surveillance.

Where it is determined that background subtraction is necessary, a baseline QC background will be determined specific to that area or region. When background subtraction is required, a QC background surveillance will be performed before a set of measurements are made to verify the applicability of the background to be subtracted. Due to the prevailing variability of the background levels across the site, the nature and extent of such surveillances will be on a case-by-case basis and should be addressed in the documentation associated with the applicable survey plan(s).

In addition to the routine QC counts, each assay report is routinely reviewed with respect to K-40 to provide indications where amplifier drift impacts nuclide identification routines. This review precludes the necessity for specific (i.e. required) after-shift QC surveillances. It also minimizes investigations of previously collected data should the system fail a before-use QC surveillance on the next day of use.

1.2.12 Data Collection Data collection to support FSS activities will be administered by a specific Survey Plan. Survey Plans may include an index of measurement locations with associated spectrum filenames to ensure that all the required measurements are made and results appropriately managed. Personnel specifically trained to operate the system will perform data collection activities.

Data collection activities will address environmental conditions that may impact soil moisture content. Logs shall be maintained so as to provide a mechanism to annotate such conditions to ensure that efficiency calibration files address the in-situ condition(s). In extreme cases (e.g. standing water, etc.) specific conditions will be addressed to ensure that analysis results reflect the conditions. As previously discussed with respect to water, when unique environmental conditions exist that may impact analysis results, conservative compensatory factors will be applied to the analysis of the data.

YA-REPT-00-018-05 Rev. 0 1.2.13 Efficiency Calibration The central feature of the portable ISOCS technology is to support in-situ gamma spectroscopy via the application of mathematically derived efficiency calibrations. Due to the nature of the environment and surfaces being evaluated (assayed), input parameters for the ISOCS efficiency calibrations will be reviewed on a case-by-case basis to ensure the applicability of the resultant.efficiency. Material densities applied to efficiency calibrations will be documented. In practice, a single efficiency calibration file may be applied to the majority of the measurements.

The geometry most generally employed will be a circular plane assuming uniformly distributed activity. Efficiency calibrations will address a depth of 15 cm for soil and a depth up to 5 cm for concrete surfaces to account for activity embedded in cracks, etc. Other geometries (e.g. exponential circular plane, rectangular plane, etc.) will be applied if warranted by the physical attributes of the area or surface being evaluated. Efficiency calibrations are developed by radiological engineers who have received training with respect to the ISOCSO software. Efficiency calibrations will be documented in accordance with procedure DP-8869, "In-Situ (ISOCS) Gamma Spectrum Assay System Calibration Procedure."

1.2.14 Data Management Data management will be implemented in various stages as follows:

" An index or log will be maintained to account for each location where evaluations for elevated activity are performed. Raw spectrum files will be written directly or copied to a central file server.

• Data Analysis - After the spectrum is collected and analyzed, a qualified Radiological Engineer will review the results. The data review process includes application of appropriate background, nuclide libraries, and efficiency calibrations. Data reviews also verify assay results with respect to the applicable investigation levels and the MDCs achieved. Data reviews may include monitoring system performance utilizing K-40. When the data analysis is completed, the analyzed data file will be archived to a unique directory located on a central file server.

" Data Reporting - The results of data files whose reviews have been completed and are deemed to be acceptable may be uploaded to a central database for subsequent reporting and statistical analysis.

YA-REPT-00-018-05 Rev. 0 Data Archiving - Routinely (daily) the centralized file server(s) where the raw and analyzed data files are maintained will be backed up to tape.

1.3 Conclusions/Recommendations The in-situ gamma spectroscopy system is a cost-effective technology well-suited to replace traditional scanning survey techniques to evaluate areas for elevated radioactivity. The static manner in which this system is operated eliminates many variables and limitations inherent to hand-held detectors moving over a surface. This system provides a demonstrably lower detection sensitivity than those offered by hand-held field instruments. This attribute qualifies this system as an alternative technology in lieu of hand-held Nal field instruments in areas where background radiation levels would prohibit the use of such detectors to evaluate for elevated gross activity. The MDC to which this system will be operated satisfies (or exceeds) criteria applied to traditional scan surveys using hand-held field instruments.

Effective investigation levels for both open land areas (i.e. soils) and for building surfaces can be derived and applied to in-situ gamma spectroscopy results. Where surrogate DCGLs are employed, investigation levels will developed on a case-by-case basis using the approach outlined in this document.

The manner in which investigation levels are derived employs several conservative decisions and assumptions. Additionally, adequate spacing applied to scanning survey locations yields an overlap in surface coverage providing 100-percent coverage of Class 1 areas and redundant opportunities in a significant portion of the survey area to detect localized elevated activity.

1.4 References I. YNPS License Termination Plan, Revision 1

2. Multi-Agency Radiation Survey And Site Investigation Manual (MARSSIM)

Revision 1, 2000

3. Canberra User's Manual Model S573 ISOCS Calibration Software, 2002

4. Decommissioning Health Physics - A Handbook for MARSSIM Users, E.W.

Abelquist, 2001

5. Canberra's Genie 2000 V3.0 Operations Manual, 2004

6. In-Situ (ISOCS) Gamma Spectrum Assay System Calibration Procedure DP-8869, Revision 0

7. Operation of the Canberra Portable ISOCS Assay System DP-8871 Revision 0

8. Technical Ref., by Thomas J. Glover.

YA-REPT-00-018-05 Rev. 0 Portable ISOCS Detector System Photos YA-REPT-00-018-05 Rev. 0 Field-Of-View Characterization Generally, the HPGe detector will be outfitted with a 90-degree collimator situated at 2 meters perpendicular to the surface being evaluated. Note that characterizing the detector's field-of-view could be performed without a source by comparing ISOCS-generated efficiencies for various geometries. If a different collimator configuration is to be employed, a similar field-of-view characterization will be performed.

To qualify the field-of-view for this configuration, a series of measurements were made at various off-sets relative to the center of the reference plane. The source used for these measurements was a 1.2 jiCi Co-60 point-source with a physical size of approximately 1 cm 3. Each spectrum was analyzed as a point source both with and without background subtract. It was observed that the detector responded quite well to the point source.

Figure 1 presents the results with background subtraction applied. Note that there is a good correlation with the expected nominal activity and that outside the 2-meter radius of the "working" field-of-view (i.e. at 90 inches) some detector response occurs. This validates that the correct attenuation factors are applied to the algorithms used to compute the efficiency calibration.

FIGURE 1 POINT SOURCE TEST (background subtracted) 2-

'* 1.5--

U 0 0.5 0

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Normally, source term adjacent to the survey units should be reduced to eliminate background interference.

YA-REPT-00-018-05 Rev. 0 FIGURE 2 POINT SOURCE TEST 06 (background NOT subtracted)

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<2-60-0 18 48 60 66 72 78 84 90 Offset (inches)

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hdgf*t SVC-O 1 Attachment A Maps Attachment A - Maps and Posting Plots List of Figures Figure Page FIGURE 1 SVC-01 RELATIVE TO STRUCTURES 2

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SVC-O1 Attachment B Data Quality Assessment Plots and Curves Attachment B Data Quality Assessment Plots and Curves List of Figures Figure Page FIGURE 1 SVC-01-18 PROSPECTIVE POWER CURVE...................................................................................

2 FIGURE 2 SVC-01 -18 RETROSPECTIVE POWER CURVE.................................................................................

2 FIGURE 3 SVC-01-18 TOTAL ACTIVITY SCATTER PLOT................................................................................

3 FIGURE 4 SVC-01 -18 TOTAL ACTIVITY QUANTILE PLOT..............................................................................

3 FIGURE 5 SVC-01 -18 TOTAL ACTIVITY FREQUENCY PLOT...........................................................................

4 The LBGR on the Power Curves have been adjusted to demonstrate the actual power of the survey.

I

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