ML042940573
| ML042940573 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 10/07/2004 |
| From: | Quennoz S Portland General Electric Co |
| To: | Document Control Desk, NRC/FSME |
| References | |
| +sispmjr200507, -RFPFR, NUREG-1757, VPN-056-2004 | |
| Download: ML042940573 (14) | |
Text
October 07, 2004 Portland General Electric Company Trojan Nuclear Plant VPN-056-2004 71760 Columbia River Hwy Rainier, OR 97048 (503) 556-3713 Trojan Nuclear Plant License NPF-1 Docket 50-344 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 Final Status Survey Report for the Main Steam Support Structure, Electrical Penetration Area and Steam Generator Blowdown Building Portland General Electric Company (PGE) received the Nuclear Regulatory Commission's (NRC) September 23, 2004 letter regarding the Final Status Survey Report for the Main Steam Support Structure, Electrical Penetration Area and Steam Generator Blowdown Building at the Trojan Nuclear Plant. In that letter, the NRC stated that the staff had completed their review of the report and concluded that the survey was conducted in accordance with the License Termination Plan; the report contains the information identified in NIJREG-1757, "Consolidated NMSS Decommissioning Guidance," Section 4.5; and the survey results demonstrate that the Main Steam Support Structure, Electrical Penetration Area and Steam Generator Blowdown Building meet the criteria for unrestricted release identified in the License Termination Plan.
However, the letter also requested that PGE consider clarifying the report to address two comments. Each of the comments, and the PGE responses are provided below.
NRC Comment Section 2.1.1, page 2-1, paragraph 2, sentences 6 & 7 - The sentences, as currently written, can be misinterpreted to mean that some surfaces were remediated and characterized, and the resultant post-remediation characterization data was used for classifying an area, rather than reflecting the pre-remediation condition. Table 2-1 presented on page 2-12 does provide clarification in a footnote which states that pre-remediation data were used to classify areas.
However, the staff recommends that PGE consider rewording the sentences on page 2-1 to reflect that pre-remediation data served as the basis for survey unit classification only.
PGE Response PGE agrees that the information provided in the report could be misinterpreted as indicated above. This section of the report has been revised to more clearly indicate that survey unit classification was based on pre-remediation data. Report replacement pages are provided in the attachment to this letter.
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- p4 VPN-056-2004 October 07, 2004 Page 2 of 2 NRC Comment Appendix C, page C The maximum reported scan measurement value was 20,090 dpmlO0 cm2 for survey unit S18059A, which is close to the 21,000 dpm/100 cm 2 investigation level. The investigation summary notes that no investigation was performed in the survey unit because of no anomalous data. The surface scan map provided on page C-23 of the Supplement to Appendix C has a notation for an instrument alarm for scan location 085, which corresponds to both the survey unit maximum value on page C-27 and the reported value of 20,090 dpm/l 00 cm 2 listed on page C-20 of the Supplement to Appendix C. Please provide clarification whether this location was investigated, including whether a static measurement was performed to quantify the residual radioactivity.
PGE Response As a matter of practice, the instrument ratemeter alarm level is usually set at approximately 80 percent of the DCGL value. In this particular instance, the ratemeter alarm was set at 17,000 dpm/100 cm2 (2,700 counts/min.). The audible alarm alerts the surveyor that radiation levels are approaching the DCGL. The surveyor responds by identifying the size of the area exceeding the alarm level. The surveyor marks the location in the field and then attempts to capture the maximum radiation level within the elevated area. The collected information is reviewed by the survey team leader and assessed by the data analyst. An investigation is not required where the maximum level is less than the investigation level. However, an investigation may be performed where determined useful. There was no investigation performed or static measurement taken in this case.
In addition to this response, Section 2.3.1.2 of the report has been revised to include the discussion above. Report replacement pages are provided in the attachment to this letter.
Should you have any questions concerning this matter, please contact Mr. Jerry D. Reid of my staff at (503) 556-6474.
Sincerely, Stephen M. Quennoz Vice President, Generation c: Director, NRC Region IV/DNMS J. T. Buckley, NMSS/DWM/DCB (3 Copies)
R. J. Evans, NRC Region IV/DNMSIFCDB D. Stewart-Smith, ODOE A. Bless, ODOE
Attachment to VPN-056-2004
FINAL SURVEY REPORT MAIN STEAM SUPPORT STRUCTURE ELECTRICAL PENETRATION AREA STEAM GENERATOR BLOWDOWN BUILDING Insert the revised pages to your Controlled Copy as indicated below.
Delete Insert Volume 1 of 2 Page i Page i Page v Pages v and vi Page 2-1 Page 2-1 Pages 2-6 through 2-11 Pages 2-6 through 2-11
TROJIAN FINAL. SURVEY REPORT- MSSS/FPAMSGR TABLE OF CONTENTS EXECUTIVE SUNMMARY......................................................................................................... vi
- 1. INTRODUCTION .. 1-1 1.1 PURPOSE AND SCOPE ............................................. 1-1
1.2 DESCRIPTION
............................................. 1-1 1.3 SITE RELEASE CRITERIA ................... .......................... 1-2 1.3.1 APPLICATION OF THE SITE RELEASE CRITERIA ..................................... 1-2 1.3.2 DERIVED CONCENTRATION GUIDELINE LEVEL ..................................... 1-3
- 2. FINAL SURVEY DESIGN .2-1 2.1 . SURVEY UNITS .. 2-2.1.1 CLASSIFICATION .................... 2-1 2.1.2 SURVEYUNIT SIZE. 2-1 2.1.3 IDENTIFICATION NOMENCLATURE .................................. 2-2 2.2 INSTRUMENTATION .................................. . 2-2 2.2.1 PORTABLE INSTRUMENTATION ................................... 2-2 2.2.2 LABORATORY INSTRUMENTATION .................................. 2-4 2.3 SURVEY METHODS .................................. . 2-5 2.3.1 SCAN MEASUREMENTS .................................. 2-5 2.3.2 STATIC MEASUREMENTS .................................. 2-6 2.3.3 SUPPLEMENTAL MEASUREMENTS .................................. 2-7 2.3.4 MEASUREMENT LOCATION IDENTIFICATION ......................................... 2-7 2.4 SURVEY PERFORMANCE ............................................ 2-8 2.4.1 SAMPLE HANDLING ........................................... 2-8 2.4.2 DATA INVESTIGATION ........................................... 2-8 2.4.3 DATA RECORDING ........................................... 2-8 2.4.4 DATA MANAGEMENT ........................................... 2-8 2.4.5 QUALITY CONTROL MEASUREMENTS ........................................... 2-9 2.4.6 PROCEDURES ........................................... 2-10 2.4.7 TECHNICAL BASIS DOCUMENTS ............... ............................ 2-10 2.4.8 CONTROL OF VENDOR SUPPLIED SERVICES .......................................... 2-11 2.4.9 TRAINING ........................................... 2-11
- 3. FINAL SURVEY RESULTS .. 3-1 3.1 MAIN STEAM SUPPORT STRUCTURE .3-1 Revision I
TROJAN FINA ISURVEY REPORT-MSSS/FPA/SGBB LIST OF EFFECTIVE PAGES Page(s) Revision Volume 1 of 2 Cover Page 0 1 1 ii through iv 0 v and vi 1-1 through 1-3 0 Figure 1-1 0 2-1 1 2-2 through 2-5 0 2-6 through 2-11 1 Tables 2-1 and 2-2 0 3-1 and 3-2 0 Tables 3-1 and 3-2 0 Figures 3-1 through 3-4 0 4-1 through 4-5 0 Table 4-1 0 5-1 0 6-1 0 Appendix A 0 Appendix B 0 Appendix C 0 Appendix D 0 Appendix E 0 Volume 2 of 2 Supplement to Appendix C 0 Supplement to Appendix D 0 Supplement to Appendix E 0 Revision 1 V
TRO IAN FINAL SURVEY REPORT- MSSSIEPAISGBB EXECUTIVE
SUMMARY
This report presents the results and conclusions of the final survey conducted by Portland General Electric Company of the Main Steam Support Structure, Electrical Penetration Area, and Steam Generator Blowdown Building (MSSSIEPA/SGBB), which are located immediately adjacent to the Trojan Nuclear Plant Containment Building. Plant systems and components were removed and contaminated structural surfaces remediated as part of the decommissioning process. A final survey of the equipment and structural surfaces remaining in the MSSS/EPA/SGBB was performed. Final survey data collection began in June 2003 and was completed in September 2003.
The final survey was performed in accordance with the final survey process described in PGE-1061, 'Trojan Nuclear Plant Defueled Safety Analysis Report and License Termination Plan (PGE-1078)," referred to as the LTP. The equipment and structural surfaces in the MSSS/EPA/SGBB were divided into 20 survey units, encompassing 5,443 square meters of surface area, and classified according to their potential for containing residual radioactivity.
Eleven survey units were classified as Class 1, five survey units as Class 2, and four survey units as Class 3. Survey data were collected from each survey unit according to data collection patterns and frequencies established for each classification. Scan measurements were performed over approximately one-third of the entire surface area and a total of 640 static measurements were collected as final survey data. In addition, 640 supplemental removable surface radioactivity measurements were collected.
The final survey data demonstrate that each survey unit meets the radiological criteria for unrestricted use specified in 10 CFR 20.1402. Based on the results of the final survey, Portland General Electric Company concludes the MSSS/EPA/SGBB meet the regulatory requirements for release to unrestricted use.
The MSSS/EPA/SGBB were some of the first areas on the plant site to undergo remediation.
Early remediation activities preceded the LTP by several years and were performed under the assumption that, for ALARA purposes, detectable levels of radioactivity had to be removed. As a result, areas with low levels of detectable radioactivity were remediated. Later, these areas, classified as Class 2 under the LTP, would not have been remediated since pre-remediation levels of radioactivity were below the radiological criteria for unrestricted use. Due to the low levels of radioactivity, these areas would not have been remediated for ALARA purposes, either.
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TROJA IV FINA I. SURVEY REPORT- MSSS/FPA/NSGR
- 2. FINAL SURVEY DESIGN The final survey was designed and performed as described in the LTP, Section 4. The Data Quality Objectives (DQO) process was used to ensure that the final survey results were of sufficient quality to support the final decision. The MSSS/EPA/SGBB were divided into survey units of proper size, which were categorized and classified according to the type and potential of residual radioactivity. Instrumentation and survey methods, appropriate to the type of radiation being measured, were used to collect scan, static, and supplemental measurements. The measurements were collected in accordance with administrative and quality controls instituted to provide assurance of accurate results.
2.1 SURVEY UNITS The MSSSIEPA/SGBB were divided into 20 survey units based on the pihysical characteristics, the potential for elevated residual radioactivity, and the size of the area with similar potential for residual radioactivity. The survey units were categorized as structures with surface residual radioactivity, where the building occupancy dose model is applied.
2.1.1 CLASSIFICATION Survey units were classified as Class 1, Class 2, or Class 3 based on the potential for residual radioactivity. Areas with residual radioactivity that exceeded the DCGL prior to remediation were divided into 11 Class 1 survey units. Areas with residual radioactivity detectable above background levels, but that did not exceed the DCGL prior to remediation, were divided into five Class 2 survey units. Areas with residual radioactivity not expected to be detectable above background levels were divided into four Class 3 survey units.
The classification process incorporated the working hypothesis that all areas had a potential for residual radioactivity above the DCGL. This initial assumption meant that a survey unit was initially considered Class 1 unless a basis for classification as Class 2 or Class 3 was identified.
Early in the final survey planning process, little or no characterization data were available.
Elevated radiation levels from contaminated surfaces, components, and equipment prevented the collection of meaningful radiological data. Some surfaces were physically inaccessible. During the course of decommissioning, the contaminated components and equipment were removed, surfaces were made accessible and a substantial amount of characterization data was collected.
The data, summarized in Table 2-1, showed that these areas could be properly classified as Class 2 or Class 3. This approach was consistent with that described in the LTP, in which areas are initially considered Class 1 areas unless a basis for classification as Class 2 or Class 3 is identified. Both scan and static measurement data collected during final survey confirmed the classification decisions made.
2.1.2 SURVEY UNIT SIZE The MSSS/EPAISGBB were divided into survey units ranging in size from 45 to 970 m2 .
Survey units were sized to ensure that survey data points were relatively uniformly distributed among areas of similar potential for residual radioactivity. Survey units were designed to have Revision 1 2-1
TRO.IAN FINA ISUIRVEY REPORT-MSSS/EPA/S RR inaccessible surface was made and the accessible surfaces were surveyed the same as other structure surfaces except that they were included in the scan coverage area when scanning was done at less than 100% coverage (i.e., Class 2 survey unit).
2.3.1.1 Scan Coverage Scan measurements of Class 1 survey units were performed over 100% of the surface area. Scan measurements of Class 2 survey units were performed over 20% of the surface area. For Class 3 survey units, scan measurements were performed over 5 to 10% of the surface area. In Class 2 and Class 3 survey units, those areas with the highest potential for elevated residual radioactivity (e.g., walkways, corners, remediated surfaces), based on professional judgment, were selected for scanning. The percent of scan coverage was determined based on the number and size of the selected areas.
2.3.1.2 Surface Residual Radioactivity Structure surfaces were scanned for beta-gamma emitting radionuclides. Typically, the detector was held less than 2 cm from the surface and moved at 5 cm/sec over an area of one square meter. Once the selected area was scanned, the latched value was electronically entered into the data logger memory. As a matter of practice, the instrument ratemeter alarm was usually set at approximately 0.8 times DCGL. The audible alarm would alert the surveyor that radiation levels are approaching the DCGL. The surveyor would respond by identifying the size of the area exceeding the alarm setpoint, mark the location in the field, and then attempt to capture the maximum radiation level within the elevated area. An investigation was performed where the maximum radiation level exceeded the investigation level.
Normally, the Ludlum Model 43-68 GFP detector with the data logger in ratemeter latching mode was used. For areas with size or geometry constraints, the Ludlum Model 44-9 pancake G-M detector was used.
Structure surfaces were not scanned for alpha-emitting radionuclides. Radiological characterization data indicated that alpha emitters were either not present or were present at activity concentrations that were insignificant in terms of dose contribution. Therefore, alpha-specific measurements of surface residual radioactivity were not performed.
2.3.2 STATIC MEASUREMENTS Static measurements were collected at a frequency and at representative locations throughout the survey unit such that a statistically sound conclusion regarding the radiological condition of the survey unit could be developed.
2.3.2.1 Surface Residual Radioactivity Static measurements to detect beta-gamma emitting surface residual radioactivity on structure and plant system surfaces were normally collected using the Ludlum Model 43-68 GFP detector with the data logger in scaler mode. For areas with size or geometry constraints, the Ludlum Revision 1 2-6
- _ -- TRO lAN?,FINATA fI.RVFY REPORT- MSSS/F~PAI/SGRR Model 44-9 pancake G-M detector was used. For each discrete measurement, the detector was placed on or near the surface to be measured, a one-minute count was taken, and the value was electronically entered into the data logger memory.
2.3.2.2 Number of Measurements To simplify the final survey process and to ensure conservatism without an associated unreasonable expenditure of resources, a minimum number of 30 static measurements per survey unit were collected. This number of measurements provided a sample population of sufficient size to assure statistical confidence in the conclusions drawn from the survey data (see Section 4.1.3.3).
2.3.2.3 Measurement Locations Measurement locations in Class 1 and Class 2 survey units were selected using a random-start systematic spacing method based on a reference coordinate system appropriate for the survey unit. Scale drawings, maps, or photographs of the survey unit were prepared, along with an overlay of the reference coordinate system. A random number generator provided the coordinates of the starting point. Subsequent measurement locations were distributed around the starting point in a systematic pattern across the survey unit area. In some cases, this led to more than the minimum number of 30 static measurements being collected.
For Class 3 survey units, measurement locations were selected using the random selection process (i.e., the reference coordinate system and a random number generator). A random number generator provided the coordinates of each measurement location.
Measurement locations that did not fall within the survey unit area or that could not be surveyed due to health and safety considerations were replaced with other measurement locations determined using the random selection process.
2.3.3 SUPPLEMENTAL MEASUREMENTS Supplemental measurements to detect removable beta-gamma emitting surface residual radioactivity on structure surfaces were collected at static measurement locations. These measurements (i.e., smears) were collected to verify removable surface radioactivity was no more than 10% of the gross activity DCGL. Smears were counted in the laboratory using the Tennelec Model LB5100.
2.3.4 MEASUREMENT LOCATION IDENTIFICATION Measurement locations were clearly identified and documented to ensure they could be relocated if necessary. Actual measurement locations were permanently marked in the field and on survey maps. A unique number identifies each measurement location. The number convention, described in Section 2.4.4, allows survey data to be referenced to specific measurement locations identified on the photographs, drawings, or maps of the survey unit.
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TROJAN FINA L STURVEY REPORT- MSSS/EPA/SGBR Physical gridding was used where practical and useful. It provided a mechanism for referencing scan measurements to a specific location. Permanent marker was used to mark the physical grid layout. The basic grid pattern used was a one-meter square grid.
2.4 SURVEY PERFORMANCE 2.4.1 SAMPLE HANDLING Smear samples collected for laboratory analysis were tracked. When sample custody was transferred (e.g., when samples were sent to the lab for analysis), a sample tracking record accompanied the sample for tracking purposes. The sample tracking (or chain of custody) record documented the custody of samples from the point of collection until final results were obtained.
2.4.2 DATA INVESTIGATION Locations, identified by scan or static measurements, with residual radioactivity that exceeded the DCGL were marked and investigated. Scan measurements were performed over 100 percent of the area being investigated. Static measurements in the form of scalar or integrated counts were performed at locations with the highest concentration of residual radioactivity. A posting plot was also generated to document the area investigated and the levels of residual radioactivity found.
Three investigations were performed. The results of the data investigations are summarized in Table 3-2. The details of the investigations are included in survey unit summary reports (see Appendix C). Depending on the results of the investigation, the identified areas within the survey unit were remediated and resurveyed, or the elevated measurement comparison was applied.
2.4.3 DATA RECORDING Measurement data were corrected for instrument efficiency, source efficiency, detector area, and measurement size as applicable, and recorded in units appropriate for comparison to the DCGL.
The recording units were dpm/100 cm2 . Measured numerical values were recorded and included values below the MDC. Instrument and material backgrounds were not subtracted from residual radioactivity measurements gathered using portable instrumentation. Instrument background was subtracted from measurements analyzed using laboratory instrumentation.
Measurement results stored as final survey data constitute the final survey of record and are included in the data set for each survey unit. The data were used for calculations to determine compliance with the site release dose criterion. The affected data were stored as characterization data where a survey unit was remediated and/or reclassified during final survey.
2.4.4 DATA MANAGEMENT The Survey Data Management System (SDMS) was used to store and process survey data. The SDMS is an electronic database that contains the final survey data and constitutes the quality Revision 1 2-8
TROJAN FINA L. SUR'VEY REPORT-AfMSSSFPA1/GBR record. Administrative controls for maintaining data integrity were incorporated into the software design. SDMS applications were tested as part of two separate tests: factory acceptance testing performed by the vendor and site acceptance testing performed by the Final Survey organization. A test plan and procedure were developed and documented for each functional module. Documented test results include the acceptance test objectives, test results, test discrepancies, and corrective actions taken to resolve the discrepancies.
Raw survey data captured in the Ludlum Model 2350-1 data logger were downloaded, electronically converted to recording units, and uploaded to the SDMS. Other data, such as laboratory data, were manually entered into the SDMS for analysis.
For electronic storage and retrieval purposes, each survey measurement is identified by a unique 15-digit code. The first seven digits are the survey unit Identification (ID) code (see Section 2.1.3). The last eight digits are the measurement ID code. The first two digits of the measurement ID code identify the type of measurement, as shown in the following table, and the last six digits are the unique measurement location ID.
Measurement Type Codes Type Code Type Description 01 l Static surface beta 04 Removable beta smears 08 Surface scanning beta Records of survey data include the surveyor identification, measurement type, measurement location, measurement instrumentation used, measurement results, and time and date measurement was taken.
2.4.5 QUALITY CONTROL MEASUREMENTS Quality Control (QC) measurements were performed to identify, assess, and monitor measurement error and uncertainty attributable to measurement methods or analytical procedures used in the survey data collection process. Two types of QC measurements were performed on a regular basis: QC checks and repeat measurements. A third type of QC measurement, duplicate sample analysis, was performed but is unrelated to the final survey of the MSSS/EPA/SGBB.
Where discrepancies were identified or acceptance criteria were not met, an evaluation was performed to determine the cause and identify any necessary follow-up actions.
2.4.5.1 QC Checks Three direct observations of survey set-up and close-out activities and scan and static measurements were performed. The observations were reviewed with the surveyors and follow-up actions such as on-the-spot correction, surveyor refresher training, changes in work process control, development of good practices, and procedural corrections and improvements were taken.
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TROJAN FINAL SURVEY RFPORT- M.SSSIEPA/IGBR 2.4.5.2 QC Repeat Measurements A set of fifteen repeat measurements was collected at each of eight measurement locations. The selected measurement locations represented a range of residual radioactivity from 4,000 to 6,000 dpm/100 cm2. For each data set, the mean value was calculated and compared to the original measurement value. Measurement accuracy was deemed acceptable where the original measurement fell within +/-20% of the mean of the repeat measurement data set. The original measurements for four of the eight measurement locations selected did not meet the QC acceptance criterion.
An evaluation was performed which determined that the static measurement locations used for collecting the QC repeat measurements should not have been selected for use with the Ludlum Model 44-9 pancake G-M detector, which was used to collect that particular set of QC repeat measurements. As a general rule, repeat measurements are collected at static measurement locations with residual radioactivity above 5,000 dpm/100 cm2. That value is about three times background for a Ludlum Model 43-68 GFP detector, which is the primary detector used. That same value represents less than two times background for a Ludlum Model 44-9. The QC repeat measurement locations all had residual radioactivity levels around 5,000 dpM/100 cm 2 .
Measurement locations with results at or near background levels are not used because of the relatively large measurement uncertainty. QC repeat measurements should be collected at measurement locations with residual radioactivity at levels greater than two times background, a practice which was inadvertently not applied in the collection of QC repeat measurements addressed here.
2.4.6 PROCEDURES Final survey activities were implemented and controlled using approved plant procedures. A list of those procedures is given in Table 2-2.
2.4.7 TECHNICAL BASIS DOCUMENTS Calculations and memoranda were prepared to document methods that were used, how the methods were derived, underlying assumptions for decisions that were made, the basis for deviations, and other information that warranted documentation. The technical basis documents developed to support/conduct the MSSSIEPA/SGBB final survey are listed in the table below.
Calculations Number Title FSC 2002-04 Gross Activity DCGL for Systems, Structures, and Components Impacted Due to Primary to Secondary System Leakage FSC 2002-08 Remediation Levels for the Primary to Secondary Affected Areas DCGL FSC 2003-03 Site Specific Scabbled Concrete Source Efficiency Factor FSC 2003-06 Area Factors for Use with the Primary to Secondary Affected Areas DCGL Revision 1 2-10
TROJAN FINAL. SIRVEY REPORT-MSSS/EPA/SGRB Memoranda l Number I Title FS-016-03 I QC Measurement Evaluation 2003-04 2.4.8 CONTROL OF VENDOR SUPPLIED SERVICES Quality-related services, shown in the table below, were procured from qualified vendors whose internal Quality Assurance (QA) program was subject to approval in accordance with the Trojan QA Program.
Vendor Supplied Services Vendor Service Ludlum Measurements, Inc. Instrument repair and calibration services Isotope Products Laboratories NIST-traceable calibration and check sources Thermo Nutech Characterization sample analysis Duke Engineering Characterization sample analysis SAIC Characterization sample analysis 2.4.9 TRAINING Final survey data collection and technical support staff members were initially trained and qualified in procedures performed by them, and received annual refresher training thereafter.
Surveyors completed scan and static survey practical training on a semi-annual basis. The following table lists the lesson modules developed and used to provide the training.
Final Survey Training Program Module Title FS-S-1 1-LP Final Survey Plan Overview FS-S-22-LP Survey Unit Design FS-S-33-LP Survey Instruments/Data Collection FS-S-55-LP Scan and Static Survey Practical FS-S-66-LP Survey Data Processing FS-S-77-LP SDMS Overview FS-S-88-LP Annual Refresher Training Revision 1 2-11