ML20217J382
| ML20217J382 | |
| Person / Time | |
|---|---|
| Site: | 07000734 |
| Issue date: | 02/11/1985 |
| From: | GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER |
| To: | |
| Shared Package | |
| ML20217J376 | List: |
| References | |
| NUDOCS 9708140197 | |
| Download: ML20217J382 (30) | |
Text
--
GA TECHNOLOGIES INC.
FINAL REPORT REMOVAL OF UNDERGROUND LIQUID RADIOACTIVE WASTE STORAGE TANKS 2.
11 7ebruary 1985 9708140197 970725
.PDR ADOCK 07000734 C
Table of Contents Summary.
iii 1..
Introduction 1
2.
Description of Tanks and Their Locations Prior to Removal-2 3
Radioactivity Measurement Techniques 4
4 Decontamination Methodology 6
5.
Data - Analysis.
7 6.
Compliance with option I criteria 21 References.
23 Tables Table 1 - Soil Sample Results - Building 9 Tank Removal 9
Table 2 - Building-2/540 Soil Sample Results 11 Table 3 - Building 31 Soil Samples.
13 Table 4 - Building 21 Soil and Gravel Sample Results -
15 Table 5 - Building 37 Soil Sample Results 17 Table 6 - Composite Sample Results - Duilding 37.
18 Table 7 - Building 37 core Sample Results and-Other Samples 19 Figure
- Figure 1 - Location of Underground Tanks Prior to Removal.
11
SUMMARY
This report provides radiological survey information regarding the removal of six underground radioactive waste storage tanks at the GA Technologies, Inc. site.
A description of the locations and the history of each tank is provided.
Radiological surveys were conducted using portable instruments during and after removal of the tanks.
In addition, representative soil samples were collected and analyzed to determine the relative extent of any radioactive soil contamination.
If contamination was present above background levels, an evaluation was done to determine compliance with previously established target criteria.
The Buildings 9. - 2/540 and 31 tank areas had no soil contamination above natural background levels.
The Building 21 and Building 37 (two _ tanks at this 4
location) areas showed levels above background, but within the Option 1 target criteria.-
It should be noted that final data and information on Building 2/307 tank pit.was presented separately (Reference 2).
The Building 2-307 tank location -
is mentioned in this report for completeness and for conformity to our plan-ning-document (Reference 1).
iii
1.0 INTRODUCTION
In accordan*ce with the planning document (Reference 1) submitted to NRC, Region V, GA Technologies (CA) has deactivated and removed underground tanks from six locations at GA's site in San Diego, California.
These tanks pre-viously served as holdup tanks for radioactive liquid waste effluent from licensed fuel facilities and associated research and development laboratories.
In accordance with the plan (Reference 1), the excavated areas resultinr, from tank removal have been decontaminated and cleaned, if required, to :aeet Option I criteria for release of land to unrestricted use.
In establishing the decontamination criteria, GA has applied the ratio-nale that the radiation exposure to individuals using the land must be within the NRC and EPA radiation exposure guidelines for Option I land release, in-cluding the requirements that the associated exposures be ALARA.
A descrip-tion of radiation measurement techniques used, decontamination methodology, estimates of residual contamination, calculated radiation doses, and their comparison with Option I allowable limits for all applicable locations are presented in this report.
1 __N
l
- C-j I.
- 2. 0 DESCRIPTION OF TANKS AND LOCATIONS PRIOR TO REMOVAL
- Figure 1 shows the location of the tanks prior to removal.
The_following provides a general description of each tank.
2.1.
Building 9 Tank The Building 9 Tank was a 750- gallon poured-in-place reinforced concrete tank.
The tank was placed underground 28 years ago and was part of the Building 9 loading dock.- The tank was originally used to dilute non-radioactive acid wastes from a metal plating operation and was later converted to a radioactive liquid waste holding tank.
The liquid col-1ected in the tank was contaminated-with low = levels of thorium and de-pleted uranium.
At a later time it was used to holdup liquid contami-nated with mixed fission and activation products.
The tank had no history of leakage.
2.2 Building 2/540 Tank l
The Building 2/540 Tank: was a 1,000 gallon poured-in-place reinforced concrete tank.
The tank was placed underground 28 years ago. The tank was used to_ hold-up liquid waste contaminated with natural uranium and thorium from metallurgical laba.- Small amounts of fission'or activation
. products were usad in these laboratories.
The tank had no history of leakage.
23 Building 2/307 Tank The Building 2/307. tank was a 1.000-gallon poured _in-place reinforced concrete tank placed underground 28 years ago.
The tank was used to hold liquid from a shielded research laboratory using primarily Cs-137.
The tank has a history of leakage.
_ The_ information on this tank was provided separately to NRC Reference 2. )
5 2_
Building 2/540 Tank The Building 2/540 Tank (also called L-540 Tank) was removed from its location on July 26, 1984 for separate disposal consideration.
The inlet drains to the tank were capped on July _6,1984, prior to tank removal, and marked.
The locations of the lines have been highlighted on the Engineering Faci 3ity Map Z-22-3.
The excavation of Buildin6 2/540 tank resulted in a pit 15'x15'x15' deep.
A beta / gamma radiation survey with Ludlum Model 3 ratemeter with a pancake GM probe showed no measurable radioactivity above background level for all four walls and the bottom floor surfaces of the excavated pit.
The background count rate with this instrument was 150 cpm.
Land area surrounding the excavated site also showed no measurable contamina-l tion.
I-The radiation survey data showed that the excavated site had even distribution of activity from natural _ background contribution.
Five composite soil samples (DS-29, 30, 31, 32 and 33) were collected for quantitative analysis.
Three of these samples (DS-31, 32 and 33) were collected in presence of an NRC Region V inspector and shared with NRC for their independent evaluation.
The results of GA and NRC Region V analysis, along with a description of the sampling location, are pre-sented in Table 2.
The average of the R -R background soil samples is 4 g given in the Table.
Any sample result lese than this average background plus two standard deviations is considered natural radioactivity.
A background soil sample was also taken by the NRC r.egion V inspector.
The result of for this background sample is also shown in Table 2.
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I
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L2.4
-Building 31-Tank The Building 31 Tank was a 1,000 gallon steel tank.- The tank was used to hold-up hand wash water contaminated with very small amounts of en-
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riched _ uranium, thorium, and activation products from the HTGR Critical
~ Facility.. The tank had no history of leakage.
2 5-Building-21 Tank The Building 21 Tank was a 1000 gallon steel tank housed in a concrete cradle-and surrounded by gravel.
The tank was placed underground 28 years ago and originally served the TRIGA-Reactor Facility.
Until establishment of the Fuel Development and Research Laboratory (FDRL),
the tank saw little use. After establishment of the FDRL the tank was used - to hold-up liquid contaminated with mixed fission and activation products. The tank _ had no history of leakage.
2.6 Building 37 Tank The Building _37 Tanks were two one-thousand gallon steel tanks.-
The tanks were placed underground 20 years ago and serve the Building-37 I
Change Rooms.
Only hand wash water contaminated with very low levels of enriched uranium and thorium drains' to the tanks. The tanks had no-known history of leakage.
W O
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30 RADICALTIVITY MEASUREMENT TECHNIQUES Soil surface beta / gamma radiation surveys (at contact) were done to determine the relative extent of any radioactive soil contamination.
Tw.
calibrated, thin window, pancake probe GM counters were used for the radiation survey.
The Ludlum Model 3, with model 44-9 pancake probe (GA Tag #15055 calibrated in September 1984),.taving a 15.2 em2 2
area and 1.2 mg/cm thin window had a natural background count rate of 150 epm (counts per minute).
The second, Ludlum Model 14A (GA Tag #84402, calibrated in August 1984) also has a pancake probe with a 15.2 cm2 2
area and 1.2 mg/cm thick window had a natural background count rate of 100 cpm.
An alpha counter (Eberline PAC-15A, GA #30356, calibrated 11/84) was also used during removal of the Building 37 tanks.
Qualitative and quantitative determination of the radioisotopic content of soil was made by laboratory analysis of representative samples obtained from excavated areas. When required, core soil samples were taken to deter-mine the possibility and the extent of any radioactive liquid waste seepage l
into the ground.
The core samples were generally 4 inches in diameter and were taken at various depths as described in this report.
Representative soil samples from five known clean locations (R -R back-4 g grounds) were obtained to determine natural radioisotopic content or soil background.
Each time approximately 1 kg of soil sample was collected from a given location.
The samples were given an identification number.
The amount of soil collected in the sample was used for the following:
a.
Analysis by GA b.
Analysis by an independent lab (if needed), and, c.
Historical sample A grinder / crusher was used to grind the soil to a fine powder consistency for quantitative sample analysis.
~~-
1 l
l Gamma spectroscopy using a Ge(L1) detector and a multi channel analyzer system was utilized to determine the nature and concentration of radioisotopes in the soil.
Calibration standards were prepared by doping clean soil with known amounts of suspected contaminants.
As noted in this report (Section 5) and in a previous report (Reference 2), many of the background soil samples were ob-I tained and split in the presence of HRC Region V inspectors for their indepen-dent evaluation.
A comparison of the soil samples analyzed at GA using the above methods, and split samples analyzed independently by NRC Region V have shown good agreement.
3
4 DECONTAMINATION METHODOLOGY Each liquid radweste holdup tank was first emptied of its contents and then removed from its underground location.
The tank contents and the tank material were handled as radioactive waste and disposed of separately in ac-cordance with the licensing requirements.
Subsequent to tank removal, all surfaces of the excavated pit and the land up to five feet beyond the pit, was surveyed for possible contamination, using a pancake probe GM meter.
The radiation survey data for all excavated pit locations discussed in this report (excluding the Building 2/307 tank area) showed presence of only natural back-ground activity.
Therefore soil decontamination was not required, nor was any soil removed from any location for separate disposal.
During excavation / decontamination, and transport activities, all normal health physics precautions were taken to keep radiation exposure to workers as ainw As Reasonably Achievable." All activities were performed in the - presence of a health physics technician. l
5.0 DATA ANALYSIS This section describes for each excavated location (1) the removal of the tank, (2) results of the radiation surveys, and (3) soil sample analyses conducted by Health Physics. Where available, the results of independent analysis of samples split with NRC Region V are also provided.
Quantitative measurements of residual radioactivity in wall surfaces of each excavated area were made to demonstrate compliance with Option I criteria for the release of land to unrestricted use.
Representative soil samples were collected and analyzed for their radioactive content.
To ensure that the soil samples were representative, radiation surveys of each excavated site were conducted and relative distribution of radioactivity established.
Radiation surveys were done using a GM counter with a pancake probe.
For the Building 2/540 pit areas to be monitored were divided into 3' x 3' grids and highest surface count rate (cpm) noted for each grid.
Other pits were not as defined and were unsafe to enter since removal of the tank caused a collapse of sur-rounding soil or gravel.
Composite soil samples were collected during removal of the tank.
Individual soil sampling locations were selected to ensure sep-1 arate sampling for any areas with hot spots.
5.1 Building 9 Tank The Building 9 Tank was removed from its location on October 8,1984 for separate disposal consideration as radioactive waste.
Since removal of the tank the inlet drain lines to the tank have been capped and marked.
The locations of these lines have been highlighted on Engineering Facilities' Map Z-22-4 The removal of the Building 9 Tank resulted in a pit 8 feet square.
A beta / gamma radiation survey with Ludlum Model 3 GM counter and Model 44-9 pancake probe showed no measurable radioactivity above background level for all four walls and the bottom floor surfaces of the excavated 4ne cacngrouno count rate with this instrument was 100 cpm yaw.
Land area surrounding the excavated site also showed no measurable contami-nation. I 1
The-radiation survey data showed that' the excavated site. had even dis-tribution of. radioactivity from natural background radiation.
For quantitative analysis,- three composite soil samples (DS-70, DS-73, and DS-74) were obtained.
Sample DS-70 was taken from the top 18 inches of all-four sides of the pit.
Sample DS-73 was taken from all accessible areas of the base of the tank pit.
And sample DS-74 was collected from various locations along the bottom of-the pit.
The samples were ana-lyzed on a calibrated Ge(Li) detector system in the Health Physics Lab-oratory.
Results for these soil samples and background soil samples are provided in Table 1.
- The Table 1 data for samples DS-70, 73 and 74 include contribution from natural background.
A comparison with background sample data shows that the residual activity in the excavated Building 9 tank pit walls and floor-is that from natural background only.
Concentrations of all iso-topes are within two standard deviation (955 confidence limits) values of the natural background activity.
The site is shown to be free of any radioactive contamination.
No soil decontamination was required.
. The open tank pit was in the loading dock area.
Therefore. health and safety considerations necessitated immediate backfilling of the clean pit.
The. Building 9 tank pit was backfilled with clean soil on-October
- 12. 1984.
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TABLE 2 3
BUILDING 2/540 SOIL SAMPLE RESULTS IU I.D.
Location Cs-137 co-60 Th-228 U-238 U-235 DS-29 Composite Collected from South
& West Sides During Tank Removal 0
0 1.4 0.1 2.0 1.0 0.131 05 1
0 1
DS-30 composite collected from North
& East Sides during Tank Re-1.62 0.01 0.04 0.007 0.16 0.05 1.4 0.1 2.5 1.0 moval 1
1 1
2 1
DS-31 composite collected from East to Center of bottom of pit:
GA Results 0.24 0.01 0.0g0.007 1.6 0.1 1.6 1.0 0.131 05.
3 0
1 3
NRC Results 0 33+0.1 NVR 1.5+0.4 1.0+0.3 NVR DE 32 composite collected from West to Center or bottom of pit:
GA Results-0.12+0.01 0
1.6+0.1 1.8+1.0 0.14+0.05 NRC Results 0.1510.05 NVR 1.510.4 1.0103 NVR[
DS 33 composite collected from rour s
walls - 5 feet from bottom or pit:
f GA Results 0.18 0.01 0.02 0.007 2.4 1.0 1 5 0.1 0.12 0.05 1
1 1
2 1
.0.18 0.06 NVR NitC Resalts 1.6 0.5_
1.0 0.3 NVR 1
1 1
Av rage or DS-29 through DS-33 (GA Results) 2.1 0.4 0.14+0.02 0.43 0 70 0.01 0.02 1.5 0.1 1
1 1
1 RR Backgrounds (Average) 1 3 0.5 0.09 0.18 0.003 0.02 1.5 1.0 0.09 0.05 1
1 1
1 2
4 g Av rage Background plus two standard
.eviations 0.27 0.023 1.8 25 0.14 Ne4 Result - Average or DS-29.through DS-33 0-0 0
0 0
0 einus average backgrou A plus two stand-
.rd deviations Ba kground (GA-B2):
GA Results 0
0.004 1 38+0.03 1.48+0.64 0.14+0.04 NRC Results NVR NVR 1.2+0.4
-S.9+0 3 NVR (1 NRC reported results as thorium and uranitas.
(2 NVR -. No value reported.
(3 Background sample results have values plus or minus two standard deviations.
L
The results of GA analysis and the NRC Region V independent analysis (Reference 3) confirmed presence of radioactivity at or near background levels.
There was ans11 amounts of Cs-137 seen in the soil samples, primarily Ds-30, a composite collected from the north and east side of the1 tank during removal. Since they were composites some top soil con-taining fallout Cs-137 could have been the cause.
Therefore Building 2/540 tank pit did not require soil decontamination.
With the concurrence of NRC Region V, the pit was backfilled on 9/5/84.
-53 Building 2/307 Tank l
Data and information for this excavated location is reported separately -
in Reference - (2).
5.4 Building 31 Tank-The Building 31 tank was removed from-its location on 8/13/84 for separate disposal consideration.
The inlet drains to the tank were removed and capped on 7/31/84, prior to tank removal, and marked.- The locations of the lines have been' highlighted on the Engineering Facility Map-Z-22-1.
A beta / gamma radiation survey of the soil surface, (contact readings)-
soil samples collected during removal of the tank, and the tank surface itself showed no evidence of radioactive contamination.
- Three composite soil-samples were collected during removal of the tank for quantitative and qualitative radioisotope analysis.- Sample DS-38 i
(top soil) DS-39 (sides of tank) and DS 40 (bottom).- Results. are reported in Table 3.-
All results were less than the average background plus two standard deviations of the average.
Therefore, the Building 9
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V TAIN.E 3 BUILDING 31 SOIL RESIN.TS j
Concentration (pC1/ gram)
- 1. g location Cs-137 co-60 Th-228 u-238 U-235 DF 38 composite soll from top or tank ND ND 0 9 0.2 22 0.07 0.04 1
1 1
DE 39 composite soil sample from sides of tank ND ND 0.9 0.2 22 0.04 0.04 1
1 1
DS 810 Composite soil sample from bottom or tank ND ND 0.8 0.2 ND 0.04g.04 1
Av rage of DS-38.39.40 ND ND 0.87 0.2 1.3 1.1 0.05 0.04 1
1 1
R R backgrounds (average) 0.09 0.18 0.03g.02 1.33 5 1.5 1.0 1
4 g 0.09 0.05 1
1
/
Av rage or backgrounds plus y
st ndard deviations 0.27 0.023 1.8 2.5 0.14 Ne result - average of DS-38.39.40 minus average of backgrounds plus tw standard deviations 0
0 0
0 0
4 55 Building 21 Tank.
The Building 21 (also called TRIGA Building) tank was removed from its location beginning November 10. 1984 The tank was removed on November 14, 1984 The inlet lines to the tank were removed, capped and marked.
The location of the. lines have been highlighted on Engineering Facil-ity's map Z-22-5.
Gravel was checked during removal of the tank using a GM counter with a pancake detector (GA #36309 calibrated 12/84).
When the drain lines were cut low level contamination (up to 1000 counts per minute) resulted in soil surrounding the pipe.
The pipe and surrounding contaminated soil was collected, and transferred to the Waste Processing Facility for disposal as radioactive waste.-
Levels
-were cleaned to background GM counter levels.
Soil and gravel samples were collected from the site when the tank was first exposed and after.the tank was removed.
The tank was in a bed of gravel, therefore when the tank was removed, no
~
defined pit remained.
The Ge(Li) scans of these samples showed several short-lived radio-isotopes in concentrations less than 1.5 pCi/ gram.
These were Sb-124 which has a 60.2 day-half-life. Xe-133 which has a 5.2 day half-life and
- Np-239 which has a 56 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> half-life.
The concentration of these i
isotopes will be insignificant after a short period of time.
The re-suits of the other radioisotopes are-shown in Table 4.
To ensure the tank did not leak, i
several large area wipes using Masslins were taken from the bottom surface of the tank and all four
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...c4 s.or Jr a vewis aetector for radioactivity.
No levels above background re-a datected.
Ochip 03r.;13 was removed from the side or the' tank under the hold down strap.
A one-hour Ge(L1)-scan showed'no contamination. I l
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O ne pit was backfilled on November 15. 1984 5.6 Building 37 Tank The removal of building 37 tanks was initiated on January 4. 1985. We tanks wre removed on January 8. 1985. for disposal as radioactive waste.
We inlet drain lines to the tanks were removed, capped and marked.
We locations of the lines have been highlighted on the engineering Facility Map Z-22-6.
A beta / gamma and alpha radiation survey of the sr munding area showed only background levels of radioactivity.
Representative soil samples were collected from top of the tank and the pit for quantitative analy-sis for possible contaminants.- 2e results of the analysis of samples DSV-1 through DSV-12 (Table 5) confirmed levels well within option 1 levels.
After counting each sample separately for 15 minutes each, samples DSV-1 through DSV-5 which were taken around tank #1 were com-posited and samples DSV-6 through DSV-10 taken around tank #2 were com-posited.
Dese composites were split with NRC Region V for their in-dependent analysis.
De composites were counted for twelve (12) hours each on a Ge(Li) detector system in the Health Physics Laboratory.
Results are presented in Table 6 which shows levels equivalent to background soil values.
During removal of the tanks, it was observed that the tanks had developed small corrosion holes. Wet soil directly under these holes (three 55 gallon drums full) was collected.
Representative samples were analyzed:(Table 7) and results were well within Option 1 levels.
O I
TABLE 5 BU'.' DING 37 SOIL SAMPLE RESULTS These samples were collected during removal of the two underground tanks.
i
- f. D.
Location Cs-137 Co-60 U-211 Th-228 DSV-1 Tank #1. North side M
M M
M III DSV-2 Tank #1, South side M
M M
M DSV-3 Tank #1 West side M
M 0.2 H
DSV-4 Tank #1. East side.
M M
M M
DSV-5 Tank #1, Bottom M
M M
M DSV-6 Tank #2. North side M
M M
M DSV-7
_ Tank #2. South side H
H M
M DSV-8 Tank #2. East side M
M M
M DSV-9 Tank #2. East side H
H H
H DSV-10 Tank #2. Bottom M
M M
M DSV-11 Tank #1. Top M
M M
M
)
DSV-12 Tank #2. Top M
M M
M (1) M Minimal means
<0.1 pCi/g es-137 (0.1 pC1/g Co-60
<0.4 pCi/g U-235
<2.0 pC1/g Th-228 (used as estimate for Th-232)
=
~
TABLE 6 COMPOSITE SAMP1.E RESULTS - BUILDING 37 I..
Ioestion.
Cs-137 Co-60 Th-228 U-235-Ta. % #1, Composite Composite of g)
DSV-1 through DSV-5 0.04 0.02 No 0.8 0.2 0.08 0.05 1
1 1
Ta.< #2, Composite Composite of DSV-6 through DSV-10 0.033 02 0.01 0.01 0.08 0.03 0.7 0.2 1
1 1
~
R
, Backgrounds (average) 0.09 0.18 0.03 0.02 1395 0.09 0.05 1
1 1
4 Av. age background plus two 0.27 0.023 1.8 0.14 st. edard deviations e
Net result - Tank-#1 & 2 composite 0
0 0
0 mit is average background plus two stsedard deviations (1:. ND - not detected
Even though the radiation survey of the pit floor and soil sample re-sults (DSV-1 through 12. DS-12 and wet soil sample) showed no evidence of radioactive contamination five core samples were taken to determine l
if there was any migration of radioactivity.
The core samples were collected starting at about three to four feet below the location of the l
tanks and identified as DS-250. 2: 1. 252, 253 and 254, several of the core - samples (i.e. DS-251. 5 5'-6 5') were recounted for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> on the Ge(L1) detector.
Levels were at background after this long count.
Results (Table 7) were less than the value given for a 15 minute count.
The results are all less than four times background and well within Option i levels.
No decontamination was required.
The tanks had been used only for hold up of very low level liquid waste originating only from hand wash water from the men's and women's change This was the reason soil contamination was at a minimum.
rooms.
TABLE 7 BUIt. DING 37 COPE SAMPt.E RESULTS AllD OTMER SAMPLES ge Samples I.D.
DS-250 4.5'-5' N
S'-6' M
M M
M 6'-7' M
M M
23 7'-8' M
M M
M 8'-9' M
M M
M D5-251 4.5'-5.5' M
M 0.27 M
5.5'-6.5' M
M 0.25 M
Sample recounted for 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 0.07+0.02 ND' O.14+0.07 1.2+0.1 6.! '-7 5' M
M M -
M-7.!*-8.5' M
M M
M 8.! '-9 5' M
M 0.40 2.1 DS-252 4 '- i' M
M 0.26 M
5'-i' M
M M
M 6'-7' M
M 0.21 M
7 '- l' M
M 0.33 M
8 '- I' M
M M
M
,8, DS-253 -
5'- i' M
M M
M y
6
M M
0.28 M
7 '- l' N
M M
M 8 '- l' M
M M
M DS-?54 5'
i' M
M M
M 6'
M M
M M
7 '- l' M
M M
M 8 '- s '
M M
0.26 M
DS-152 M
M M
M Composite c ollected near the six pipes tealing to.he tanks Rep.esentat we samples collected M
M M
M beneath Tan: #2 (aNil - not tetected)
(1) Depth c,' core samples represent depths from the bottom or the tank.
(2) M - see.ns minimal amount for a 15 minute count as rollows:
<0.1 p :1/g Cs-137
<0.4 pC1/g U-235
<0.1 p :i/g Co-60
<2.0 pCi/g Th-228 (used as estimated value for Th-232) i..
- i.. -. _ _..
a 6.0 COMPLIANCE WITH OPTION I CRITERIA In evaluating the soil sample results to ensure compliance with Option 1 levels, the following was considered.
1.
Target criteria (Option 1) for Soil Decontamination Option levels for soil contamination are specified in Reference 1 and are summarized below.
Radionuclide Concentration (pci/ gram U-238 35 U-235 and U-234 Th-232 30 Co-60 10 8
Cs-137 15 or combinations thereof where the sum of the fractions do not exceed one.
2.
Natural background level in soil was determined by analyzing the soil samples collected around GA.
These were identified as R4 through Rg soil samples.
The average and standard deviation (two) for these results is given in Tables 1 through 6.
A sample result greater than the average background plus two standard deviations was considered positive.
The results given to us by the NRC on the analysis of these samples by Oak Ridge Associated Universities were in good agreement but generally were somewhat higher than our results.
3.
Soil semples collected at the building 9. Building 2/540 and Build-ing 31 tank locations during and after removal of the tanks were analyzed.
Results were not distinguishable from natural background levels.
These areas have no soil contamination and are therefore within Option i levels.
4
,e s
4.
Soil samples collected at the Building 21 and Building 37 locations (Tables 4-7) showed some contamination above background levels.
The Building 21 soil levels were just slightly above background due to some contamination released from the drain pipe after cutting.
The Building 37 soil concentrations were above background levels but well within the Option 1 criteria.
This small unount of contamina-tion is reasonable because the tanks were used only for holdup of j
wash water from the men's and women's change room.
REFERENCES
- 1. " Release of Certain Activity Sites for Unrestricted Use,"
GA letter 696-6077 dated 16 November 1984
_2.
" Request for Approval to Backfill L-307 Pit." GA letter 696-6083 dated 30 November 1984 l
i l
3.
NRC letter Docket No.70-734 dated 5 October 1984 signed by F. A.
Wnslawski._,
INTERNAL G21RESPONDD6CE 4
IN ERY FRON:
L. R. Quintan REFER To: LRQ:85 :5t, TO:
F. 0. Boid/W. R. Mowry DATE: March 14, 1985 SLBJECT: Results of Core Samples Collected Merch 7, 1985 Near Building 31 On March 7, 1985, core samples were collected near Building 31 from the same location where the underground tank had been removed in August,1984.
These samples were collected as a result of a request made by Region Y NRC Inspectors af ter they analyzed a soll sample (composite) they received from GA in October,1984.
Their results showed the presence of Cs-137, Co-60 and U-235, at levels exceeding Option 1 limits.
Our results had shown only natural background radioactivity levels.
The results reported to me by Paul Zurakowski and Buddy Brock, from the NRC Region V Of fice, were similar to the results we had obtained of the analysis of the sludge collected from inside the tank.
Buddy Brock was the first to see the correlation.
There is a strong possibility that the sample sent to them was s' sludge sample and not the soll samples.
The NRC requested that core samples be collected to assure and confinn that the soll remaining af ter removal of the tank was Indeed " clean".
Paul Zurakowski ' observed the core sampling and processing.
Attachment I and Table 1 provide data on the collection, analysis and results of the core sampling.
LRQ:ms Table 1
ATTA0iMENT 1 Rulldina 3j, h lamnla Rasults Core samples were collected near Building 31 on 3-7-85 from the same location where the underground tank was removed.
The core samples were collected by Southern Calif ornia Soll and Testing Company.
Three core samples were collected at depths from 15' to 23', for Core No.1,13.5' to 23' for Core No. 2, and 13.5 to 18.5' for Core No. 3.
All three samples were collected as to ensure the sampling of both fill soll and natural undisturbed soll.
Paul Zurakowski, a Region V NRC Inspector, observed the collection and l
preparation of the samples.
Bete / gamma radiation measurements were conducted on the core samples af ter collection, using a GM (Model 14A) counter, serial number 85587 calibrated 11/28/84 No radiation above natural background levels was detected.
The samples were given an Identification number and processed on 3-7-85 and 3-8-85.
The samples were deled and ground to a fine powder consistency for quantitative sample analysis.
The samples were shared with Paul Zurakowski.
The Identification number and location collected are provided below:
Aglj, h
,LD LocATlON Fill Soll 05-268 Composite from Core #1 15-18 feet depth Natural Formation 05-269
" 18-21 feet depth Natural Formation D5-270
" 21-23 feet depth-Fill Soll 03-271 Core #2 13.5-17.5 feet depth Natural Formation 05-272
" 17.5-20.5 feet depth Natural Formation 05-273
" 20.5-23 f eet depth Fill Soll DS-274 Core #3 13.5-15.5 feet depth Natural Formation DS-275
" 15.5-18.5 feet depth