ML20196H529
| ML20196H529 | |
| Person / Time | |
|---|---|
| Site: | 07000734 |
| Issue date: | 02/26/1999 |
| From: | Gonzales L, Maschka P, Ramirez E GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER |
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| NUDOCS 9907060368 | |
| Download: ML20196H529 (17) | |
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l FINAL RADIOLOGICAL SURVEY l
PERFORMED AT GENERAL ATOMICS' I
TEST TOWER LAND AREA I
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L Prepared By: Efriam Ramirez, Paul Maschka, Laura Gonzales, i
Scott Cowan, Richard Stowell and John Turner February 26,1999
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j'# 188e* M88" g.
TABLE OF CONTENTS INTRODUCTION
..............................................................1 SITE DESCRIPTION............................................
..............1 PREVIOUS ACTIVITIES (HISTORY OF USE)...................................... 1 CRITERIA FOR RELEASE TO UNRESTRICTED USE................................ 2 Exporure Rate Guideline...........................
.......................2 Soil Criteria
............................................................2 INSTRUMENTATION
..........................................................3 BACKGROUND MEASUREMENTS............................................
3 Soil Concentrations
.......................................................3 Exposure Rate Measurements
...............................................3 FINAL SURVEYS PE RFORMED.................................................. 4 Objectives and Responsibilities.............................................. 4 Classification o f Area................................................... 4 Final Survey Plans
......................................................4 Soil Sampling............................................................ 5 Exposure Rate Surveys.................................................... 5 RE S ULTS O F SURVEYS........................................................ 5 Soil S ampling.........................................................
5 Exposure Rate Measurements.............................................. 5 CON C L U S I ON.............................................................. 6 TABLES Table 1:
Soil Sample Results................................................ T-1 Table 2:
Exposure Rate Measurements....................................... T-2 Table 3:
Background Radionuclide Concentrations.............................. T-3 FIGURES (unpaced)
Figure 1:
Plan View ofGeneral Atomics Site Figure 2:
Test Tower Land in Relation to Surrounding Facilities Figure 3:
Test Tower Land Area and Soil Sample Locations APPENDIX
" Final Survey Plan for Test Tower Land" dated October 20,1998 & Addendum #1 dated February 22,1999.
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$ General Atomics Test Tower Land Area Final Radiological Survey Report INTRODUCTION General Atomics (GA) is continuing its efforts directed at dect,ataminating, as appropriate, and obtaining the release to unrestricted use of selected facilities and land areas at General Atomics.
l GA has recently completed the Final Radiological Survey of the open land area identified as " Test Tower Land" located at GA's Sorrento Valley Site.
GA is requesting both the Nuclear Regulatory Commission (NRC) and the State of California for the release of the " Test Tower Land" area to unrestricted use.
This report documents the results of the radiological measurements and soil sampling completed on the " Test Tower Land" and demonstrates that this area meets the approved criteria for release to unrestricted use. The total surface area to be released to unrestricted use is ~ 3.8 acres.
SITE DESCRIPTION A plan view of the GA Site is shown in Figure 1. The relationship of this land area to other facilities at GA's Sorrento Valley Site is.;hown in Figure 2. The open land area, identified as " Test Tower Land," and soil sample locations are shown in Figure 3.
The " Test Tower Land" includes the entire open land area surrounding Buildings 35,35-1,36 and 45 as shown in Figure 3. Most of this surface area is covered with either asphalt or concrete. The sampled portions of the Test Tower Land area only includes surfaces that are not covered with concrete or asphalt.
PREVIOUS ACTIVITIES (HISTORY OF USE)
History reveals no prior knowledge of work involving radioactive materials or storage of radioactive materials ever being associated with this open land area. Furthermore, radiological surveys were previously performed outside Building 35 (Test Tower), including soil sampling of the drainage (runoff) area from a concrete trough inside the building. The results of surveys performed in the drainage area and on the concrete / asphalt pads outside the Test Tower can be found in the report titled " Final Radiological Survey Report for Building 35" previously submitted to the NRC and State of California [Refs: GA letter No. SNM-2983 to the NRC (C. Gaskin) and GA letter No. CAL-2982 to the State (D. Wesley and S. Hsu), both dated September 30,1998). Radiological measurements 1of6
+ General Atomics' Test Tower Land Area Final Radiological Survey Report showed that no contamination was detected outside Building 35 and that soil sampling results were well below the release criteria.
In addition, separate individual final surveys have been performed for each building located on the
" Test Tower" land area (i.e., buildings 35,35-1,36 and 45). The results of those other surveys demonstrated that each of the buildings located on the " Test Tower" land area meet the approved criteria for release to unrestricted use. The results of those other surveys are documented in separate final survey reports which support the request for release to unrestricted use of each building.
CRITERIA FOR RELEASE TO UNRESTRICTED USE EAposure Rate Guideline The guideline value for exposure rates measured at I meter above the surface, is 10 R/hr above background levels.
Soil Criteria The predominant radionuclides found in soil at GA and the soil release criteria in pCi/g is provided below:
Cs-137 15 pCi/g Co-60 8 pCi/g Thorium (Th-228 + Th-232) 10 pCi/g Enriched Uranium (U-234 + U-235) 30 pCi/g Depleted Uranium 35 pCi/g If more than one radionuclide exists, the sum of the fractions of the concentrations is calculated a follows:
C
-EdL, s
I C, = The average concentration of radionuclide iin the soil above background levels.
L, = The release criteria for radionuclide i.
The sum of the fractions must be less than or equal to one for the soil to meet the release criteria.
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f Genera / Atomics Test Tower Land Area Final Radiological Survey Report INSTRUMENTATION The instrument used for conducting exposure rate measurements was a Model 19 microR meter manufactured by Ludlum Measurements, Inc. The microR meter used contains a 1" x 1" Nal(TI) scintillation detector mounted internally and has five ranges that provide readings from 0-5000 pR/hr. Two microR meters were used to conduct the exposure rate measurements. The calibration due date was 02/03/99 for instrument S/N 87120 and 05/11/99 for instmment S/N 144068.
Soil samples were counted for isotopic content with a Canberra Low Sensitivity Gamma Spectroscopy MCA System using a high purity Germanium Detector manufactured by Canbena Industries, Inc. located in GA's Health Physics Laboratory. The lower sensitivity depends on the counting time and the type of sample counted. The system is calibrated using NIST traceable standards and performance checked daily.
BACKGROUND MEASUREMENTS Soil Concentrations Natural background concentrations measured by gamma m. ascopy in soil near the GA site have been established (at the 95% confidence level) and are provided in Table 3. The locations from which these samples were taken are also provided in Table 3. Soil samples were counted for a minimum of 30 minutes each, except for sample (TTL-7) which was counted for 10 % hours. A 30 minute count is sufficient to detect the radionuclides ofinterest (Cs-137, Co-60, U-235, U-238 and thorium daughters) at levels well below GA's approved soil release criteria.
Exnosure Rate Measurements Typical exposure rate background for this site is about 15 R/hr measured at I meter from the surface. This value can be measured south of Building 15 (an office building on the non-impacted eastern portion of the GA site). Measurements taken offsite in 10 different locations over a period of a year also give an average of about 15 R/hr(measured at 1 meter from the surface). Normal background exposure rates increase to about 22 R/hr at 1 meter from the surface in small rooms with concrete floors and walls, and up to 28 R/hr inside concrete lined trenches or concrete lined pits (background measurements inside a concrete pit near Building 2 confirmed this).
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f General Atomics Test Tower Land Area Final Radiological Survey Report FINAL SURVEYS PERFORMED i
Obiectives and Resnonsibilities The objectives of the final survey plans were (1) to demonstrate that the soil sample results were well below GA's approved release criteria for unrestricted use, (2) to show that the exposure rate measurements in all sampling locations were less than 10 R/hr above background measured at I meter above the surface and on contact with the surface, (3) to show that exposure rate measurements taken throughout this open land area measured at I meter above the surface were less than 10 R/hr above background and (4) to show that the exposure rate measurements at all storm drain locations were less than 10 R/hr above background measured at I meter above the drain and on contact with the drain's surface.
MicroR surveys and soil samples were taken only by qualified Health Physics Technicians having a minimum of three years Health Physics experience and in accordance with approved Survey Plans.
Soil samples were analyzed in GA's Health Physics Laboratory which maintains an effective QA program.
Every exposure rate measurement conducted was documented on a daily basis to a worksheet or drawing showing the approximate locations surveyed. The documentation included the results of the measurements (including units), the technician's signature, date, instrument used (including the model and serial number), calibration due date, background readings (if applicable) and any other pertinent infonnation.
Each soil sample collected was properly logged, labeled, packaged and tracked and the sampling locations were documented to a drawing.
Classification of Area Non-Impacted Arca: The Test Tower land area was categorized as "non-impacted" because no radioactive material was ever known to be used or stored on this open land area. Therefore, no radiological surveying was required. However, exposure rate measurements and soil sampling were conducted to demonstrate that this area meets the criteria for release to unrestricted use.
Final Survey Plans Survey / sampling plans were developed based on the previous history of the land area and the buildings within the land area, the radionuclides of concern, the various types of surfaces, the potential for contamination and the classification of the area (non-impacted).
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f General Atomics Test Tower Land Area Final Radiological Survey Repon The surveys and sampling were completed in accordance with an approved written Final Survey Plan. A copy of the Survey Plan is provided in the Appendix to this report: " Final Survey Plan for Test Tower Land" dated October 20,1998 and Addendum #1 dated February 22,1999.
l Soil Samnling A total of twelve (12) locations were selected for soil sampling and exposure rate measurements.
I The locations selected took into consideration the proximity of the land area's boundary, potential drainage from other sites, availability of soil and accessibility of the sampling locations.
These " surface" soil samples were collected from 12 individual locations each with a sample size of I
approximately I kilogram. The samples were collected to a depth of 15 cm (0-6") using manual equipment (i.e., long handled spade). Each soil sample was placed into a properly labeled plastic bag. Each sample was properly logged, labeled, packaged and tracked. All debris (i.e., grass, rocks, sticks, asphalt and foreign objects) were removed from each sample.
Each soil sample was crushed to reduce large lumps, dried, placed into a tared marinelli beaker I
(filled to the top), weighed, transported to and counted in the GA Health Physics Counting Laboratory by gamma spectroscopy.
I Exnosure Rate Surveys Exposure rate measurements (in R/hr) were taken at the surface and at I meter from the surface at I
each of the twelve (12) soil sampling locations. Exposure rate measurements were also taken at the surface and at I meter from the surface at each of the storm drain locations. Furthermore, exposure rate measurements were conducted at I meter from the surface throughout the open land area.
I RESULTS OF THE SURVEYS Soil Sampling The results are reported in Table 1 (in pCi/g) for each radionuclide ofinterest. The results indicate that the values are all well below the soil release criteria.
Exoosure Rate Measurements All exposure rate measurement results were less than 10 R/hr above background at contact with the surface and at I meter from the surface.
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f General Atomics Test Tower Land Area Final Radiological Survey Report The results of exposure rate measurements taken at each of the twelve (12) soil sampling locations are provided in Table 2.
The open land area was scanned with a micro R meter. A total of 92 exposure rate measurements taken at I meter from the surface ranged from i1 to 20 R/hr. These measurements were taken above soil, asphalt and concrete surfaces. The average of the 92 measurements was 17 R/hr.
A total of 16 storm drains were investigated. Exposure rate measurements taken at I meter from the surface of these drains ranged from 13 to 18 R/hr. Exposure rate measurements taken at contact with the surface (e.g., metal gratings) of the drains ranged from 8 to 19 R/hr.
One of the 16 storm drains is a corrugated metal culvert (rainwater runoff) which exits into an asphalt lined trench. An exposure rate measurement taken at 1 meter from the surface at the exit of the metal culvert read 20 R/hr and a measurement on the surface of the bottom of the trench (~ l foot in depth) read 23 R/hr. The slightly higher measured value on the bottom of the trench is explained by the detector being in close proximity to three asphalt surfaces.
CONCLUSION Exposure rate measurements and soil sample results provided in this report, demonstrate that the area designated as " Test Tower Land," meets the approved guidelines for release to unrestricted use.
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Table 1: Gamma Spectroscopy Results of Soil Samples Collected from the Test Tower Land Area 8 23sU 235U Total Thorium 337Cs 6 Co Sample ID 92.77 kev peak IB6 (144] kev peak 22'Th + 222Th 661.6 kev peak Average of 1173/1332 kev peaks TTL1 1.58 0.12 2.06 0.06 ND TTL 2 1.70 0.19 2.33 0.07 ND TTL 3 2.34 0.14 3.19 0.11 ND TTL 4 1.60 0.14 1.78 ND ND TTL 5 2.13 0.14 2.80 0.07 ND TTL 6 1.60 0.19 1.98 ND ND TTL 7 8 1.32
[0.08]
1.63 0.02 ND TTL 8 2.37 0.13 2.09 ND ND TTL 9 1.87 0.17 2.37 0.05 ND TTL 10 2.39 0.24 1.72 0.13 ND TTL 11 0.73 0.09 1.56 ND ND TTL 12 ND 0.08 1.35 ND ND Average 1.78 0.14 2.07 0.07 ND
)
i Radionuclide Concentrations are reported in pCi/g. Background values are upl subtracted.
2 This sample was counted for 10 % hrs. All other sample counts were for 30 minutes.
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4 Table 2: Exposure Rate Measurements - Test Tower Land pR/hr LOCATION on the surface at I m TTL-1 15 14 TTL-2 17 16 TTL-3 19 18 TTL-4 15 14 TTL-5 19 18 TTL-6 18 17 TTL-7 12 13 TTL-8 17 17 TTL-9 18 16 TTL-10 18 17 TTL-11 15 14 TTL-12 15 16 Average 17 16 T-2
Table 3:
Typical Background Radionuclide Concentrations (pCi/g) in Soil '
Sample Cs-137 Th-228 Ra-228 Total U-238 U-235 (Th-232) 2.N,"*
ID 3 Th-232 AJ ND 2 1.28 i 0.07 1.47
- 0.14 2.75 1.98 + 0.31 0.15
- 0.03 G2 0.12
- 0.03 0.92
- 0.07 1.01 0.12 1.93 1.86 0.29 0.12 0.02 AC ND 1.29 0.07 1.34
- 0.14 2.63 2.27 0.27 0.20
- 0.03 BKG-1 ND 1.40
- 0.16 1.44
- 0.28 2.84 2.06
- 0.48 0.19 0.06 BKG-2 ND 1.54 0.15 1.57 0.27 3.11 2.30 0.45 0.17
- 0.05 BKG-3 ND 1.40 0.14 1.62 0.26 3.02 ND 0.19
- 0.05 BKG-4 ND 0.67 0.09 0.84
- 0.17 1.51 1.15
- 0.37 0.09 0.04 BKG-5 ND 1.51
- 0.16 1.79
- 0.31 3.30 2.77 + 0.67 0.12 0.06 BKG-6 ND 0.68 0.09 0.76
- 0.16 1.44 ND 0.08
- 0.03 BKG-7 ND 1.17
- 0.12 1.28 0.22 2.45 1.83 0.43 0.11
- 0.04 Mean
- 2 o 1.19
- 0.64 1.31 C.68 2.5
- 1.32 2.03 0.93 0.14 0.09 Samples gamrra scanned for I hour.
2 ND=
< 0.1 pCi/g for Cs-137, < l.0 pCi/g for U-238 8
Samples collected in June and August 1993, typically about 1-2 miles from the Building 37 site at the following locations:
AJ Collected on a hillside west of Building 39 & northwest of building 37, ~3' from GA's fence.
G2 Collected about 1200 feet west of Bldg 1 (near T.P. RD.), and ~7/8 of a mile southwest of Building 37.
AC Collected about I mile southeast of the main site & about 2 miles southeast of Building 37.
g BKG-1 Collccted about 1 mile from Building 37 at the Scripps Hospital Entrance, cast of Genesse Ave.
B BKG-2 Collected about 1.2 miles from Building 37 at Sorrento Court Rd. by North entrance to Post Office.
BKG-3 Collected about 1.5 miles from Building 37 at Sorrento Vista Parkway near Lusk Blvd. South.
BKG-4 Collected about I mile west from Building 37, west off Genesee corner of North Torrey Pines Road and Torrey Pines Scenic Drive.
BKG-5 Collected about 2 miles west of GA off of La Jolla Shores Drive.
BKG-6 Collected about 2 miles northwest of Building 37 on North Torrey Pines Road.
BKG-7 Collected about 2 miles near V.A. Hospital on La Jolla Village Drive (southwest).
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l Appendix to Final Radiological Survey Performed at General Atomics' Test Tower Land Area dated February 26,1999
" Final Survey Plan for Test Tower Land" dated October 20,1998 Addendum #1 to the " Final Survey Plan for Test Tower Land" dated February 22,1999
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October 20,1998 7.gg Prepared by: Paul Maschka Approved by: Laura Gonzales kwg j h)
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9 Final Survey Plan for Test Tower Land
Background
The " Test Tower Land" includes the entire land area surrounding Building 35,35-1,36, and 45 I
as shown in Figure 1. The area is "non-impacted". No radioactive material was known to be used or stored on this land, therefore, limited surveying will be performed. Most of the area is either covered with asphalt or concrete. The " Test Tower Land" only includes the land areas.
Final surveys for a h building were performed and separate reports written (or will be written) for the buildings.
l The Final Radiological Survey Report for Building 35 describes the surveys performed outside Building 35 including the soil sampling of the drainage area from a concrete trough inside the building found to be contaminated with Cs-137 and Co-60 during survey of Building 35 and the results of surveys performed on 2 concrete / asphalt pads outside of Building 35. See the Final Radiological Survey Report for Building 35 for more information.
Survey Plan Collect 12 soil samples in the areas indicated in Figure 1. At each location, make an exposure
)
rate measurement on the surface and at I m above the surface.
Alert Levels I
Soil sample results above the 75% of the release criteria (Paul Maschka or Laura 1.
Gonzales to review the gamma spectroscopy results).
2.
Exposure rate measurements above 20 R/hr.
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Prepared by: Paul R. Maschka y[M [ M
- February 22,1999 Final Survey for Test Tower Land Addendum #1 l
Survey Plan Perform a walkover survey with a microR detector at one meter above the surface l
covering the entire area.
Carefully su'rvey any drains that are found.
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