ML20235Y907
| ML20235Y907 | |
| Person / Time | |
|---|---|
| Site: | 07000036 |
| Issue date: | 02/13/1989 |
| From: | Cotten P OAK RIDGE ASSOCIATED UNIVERSITIES |
| To: | NRC |
| Shared Package | |
| ML20235U469 | List: |
| References | |
| CON-FIN-A-9076 NUDOCS 8903140676 | |
| Download: ML20235Y907 (9) | |
Text
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RADI0IDGICAL SURVEY OF CONSTRUCTION SITE COMBUSTION ENGINEERING, INC.
HEMATITE, MISSOURI Prepared by:
P. R. Cotten t
INTRODUCTION The Cumbustion Engineering, Inc.
facility in Hematite, Missouri, manufactures nuclear fuels under Nuclear Regulatory Commission (NRC) special nuclear materials license SNM-33.
The plant is in the process of constructing additional manufacturing and warehouse space and a new utility area to increase production capacity.
This new construction will be located between Buildings 240 and 255 (Figure 1).
Construction is being performed in two phases.
Phase 1 extends from Building 255 up to the present utility area and occupies a surface area of approximately 26 m x 70 m; Phase 2 construction, scheduled to begin later in 1989, will connect the Phase 1 construction area with Building 240.
In preparation for Phase 1 construction, two former buildinbs (Buildings 250 and 251) were removed.
These buildings had been used primarily for storage of bulk chemicals, storage of containerized enriched uranium, and shipping / receiving activities; processing of uranium was never conducted in either of these buildings.
In addition to the demolition of the two buildings, a section of contaminated sewer line was excavated.
Based on previous use of the construction site, the potential for radiological contamination was considered low. However, Combustion Engineering had performed surveys of the area, to document that the site satisfied the NRC guideline of 30 pCi/g of total uranium in the soil. At the request of the NRC, the Radiological Site Assessment Program of Oak Ridge Associated Universities Prepared by the Manpower Education, Research, and Training Division of Oak Ridge Associated Universities, Oak Ridge, Tennessee, under interagency agreement, (NRC Fin. No. A-9076) between the U.S. Nuclear Regulatory Commission and the U.S. Department of Energy.
February 13, 1989 8903140676 090224 PDR ADOCr. 0700 6
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(ORAU) conducted an independent survey of the Phase 1 construction sit-on January 24,
- 1989, te confirm the accuracy of the licensee's survey and to provide additional data on the site status, relative to the NRC guidelines.
Procedures and results of that survey are presented in this report.
SURVEY PROCEDURES At the time of the survey, construction had already begun. Most of the footings and foundation for the building had been poured and three walls had been erected.
To assist construction equipment in the area, approximately i
30 cm of gravel had been spread over the construction site.
i 1.
A 10 m x 10 m reference grid system was established in the Phase 1
(
4 construction area; the grid origin wcs located in the southwest corner of the new structure. This grid is shown on Figure 2.
2.
Beta-gamma and gamma scans were conducted over soil surfaces within the gridded portion of the construction site and extended to about 1 m around the perimeter of the area, Thin-window GM and NaI(Tl) gamma scintillation detetors with audible indicating scaler /ratemeters were used to perform scanning surveys.
Locations of elevated radiation levels were noted for further investigation.
3.
Surface soil samples were obtained at ten locations and subsurface (depth - about 0.5 m) soil samples were obtained at four locations (Figure 2).
Samples were collected from exposed soil areas (gravel removed) and trenches. A sample was also obtained from a location of slightly elevated direct radiation.
Samples were analyzed by gamma spectrometry at the laboratory facilities in Oak Ridge, Tennessee; 1
several samples were also analyzed for
> topic uranium by alpha spectroscopy.
4.
Exposure rate measurements were performed at the surface and 1 m above the surface at each of the sampling locations, using a gamma 2
scintillation detector, cross calibrated for enriched uranium with a pressurized ionization chamber.
RESULTS Surface scans identified elevated direct radiation levels throughout an area adj acent to the southern portion of Building 255. The source of this radiation was uranium, stored inside Building 255.
Because of the covering of gravel -fill' over most of the area, scanning was inconclusive as to the condition of much of the underlying soil.
One area of surface contact radiation, significantly above the ambient level, was detected at grid location 23.5N, 25E. This finding was brought to the attention of the. licensee and additional soil was removed from this location.
Exposure rates at sampling locations ranged from 6 to 28 pR/h at both surface contact and 1 m above the
. surface (Table 1).
For comparison, the background exposure levels in the area of this facility were in the range of 6 to 10 pR/h; this range is typical of normal background radiation in this region of Missouri. Higl.er levels were all near the extreme eastern portion of the construction site and were attributable to the materials stored inside Building 255.
Concentrations of uranium in soil samples are presented in Table 2.
Levels of U-238 ranged from
<0.5 to 38.1 pCi/g; U-235 levels ranged from <0.2 to 24.7 pCi/g. The highest concentrations of both uranium isotopes were in sample B1 from grid coordinate 23.5N, 25E. This was the location, identified by the surface scans.
Alpha spectroscopy on several of the higher level samples indicated a ratio of U-234 to U-235 activity of approximately 26.
Based on this isotopic ratio, soil samples from locations 3, 5, 7, 11 and B1 contained total uranium above the 30 pCi/g guideline level; samples from locations 2, 10, and 13 have associated statistical uncertainty levels which make them borderline with respect to the guideline values.
The licensee remediated areas in the vicinity of samples 3, 5, 7, 11 and B1 and provided follow up samples from those areas for ORAU analysis. Results of these follow-up analyses (Table 3),
indicate that concentrations have been reduced to below or near the guideline levels.
3 I
i CONCLUSIONS i
ORAU'S' survey of the Phase 1 construction area indicated residual enriched uranium contamination at five locations, exceeding the NRC guideline values, and concentrations near guideline values 'at several other ' locations.
-Additional soil removal was effective in eliminating the " hot spots" and reducing the Phase 1 area to within the guideline levels.
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SAMPLING LOCATIONS h SURFACE SAMPLES h
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METERS FIGURE 2: Soil Sampling Locations in Phase I Construction Area 6
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TABLE 1 EXPOSURE RATE MEASUREMENTS -
COMBUSTION ENGINEERING, INC.
HEMATITE, MISSOURI Grid Exposure Rate (uR/h)
Locationa Coordinate (at 1 m above (at surface surface) contact) 1 10N, 12E 8
9 2
1.5N, 2E 6
6 3
1.5N, 22.5E 28b 28b 4
17.5N, 15E 9
9 5
20N, 25E 16bb 6 28N, 21E 11b lib 7 40N, 25E 9 9 8 44N, 13E 6 8 9 SIN, 21E 8 8 10 60N, 10E 8 8 11 57N, 0.5E 8 8 12 28N, 12E 8 8 13 68N, 0.5E 6 8 14 41N, 2E 6 8 B1 23.5N, 25E 14b,e 14b,c aRefer to Figure 2. bElevated levels, due to uranium storage in nearby Building 255. measurement af ter additional cleanup actions. 7
r I 6 I .l l TABLE 2 URANIUM CONCENTRATIONS IN SOIL. b COMBUSTION ENGINEERING, INC. L HEMATITE, MISSOURI 1 Grid Uranium Concentration (pCi/g) . Locationa Coordinate U-235 U-238 Total Ua 1 10N, 12Eb 0.2 0.lc <0.6 6.0 2 1.5N, 2Eb, 1.0 0.3 5.6 0.4 32.6 3 1.5N, 22.5E 6.1 1 0.4' 17.4 1 1.1 182.le 4 17.5N, 15E 0.5 1 0.2 <0.5 14.0. 5 20N, 25E 2.4 0.3 4.3 1 0.4 69.le' b .<0.2 1.3 1 0.6
- 6. 7.
6 28N, 21E b '7 4CN, 25E 8.6 0.6 30.4 1.2 262.6e 8' 44N,.13E 0.7 1 0.3 2.5 t 0.7 21.4 b <0.2 1.2 0.5 6.6 9' 51N, 21E 10 60N, 10E 0.8 1 0.3 2.1 1 1.2 23.7f 11 57N, 0.5E 1.4 1 0.3 2.7 1 0.5 40.5e 12 28N, 12E <0.2 <0.8 6.2 13 68N, 0.5E 1.1 0.3 2.9 0.8 32.6f 14 41N, 2E <0.2 1.3 1 0.5 6.7 B1 23.5N, 25E 24.7 1 0.2 38.1 1.1 705.0e Guideline 30 aRefer to Figure 2. bSubsurf ace soil; sampling. depth approxf mately 0.5 m. uncertainties represent the 95% confidence levels,-based only on' counting statistics; additional laboratory uncertainties of 1 6 to 10% have not been propagated into these data. .dCalculated, utilizing U-234/U-235 activity ratio of 26. GExceeds guideline level regardless of statistical uncertainties. fMay exceed guideline level based on statistical uncertainties in analytical data. 8
u TABLE 3 URANIUM CONCENTRATIONS IN SOIL FOLLOWING ADDITIONAL REMEDIATION COMBUSTION ENGINEERING, INC. HEMATITE, MISSOURI Uranium Concentration (pCi/g) Samplea Location U-235 U-238 Total UC 3A 1.5N, 22.5E 0.3 1 0.3b <0.7 8.8 5A 20N, 25E <0.2 2.1 0.3 7.5 7A 40N, 25E 0.3 0.1 <0.6 8.7 11A 57N, 0.5E 0.4 0.1 2.410.4 13.2 BIA 23.5N, 25E 0.8 i 0.1 2.1 1 0.4 23.7 aRefer to Figure 2. bUncertainties represent the. 95% confidence levels, based only on counting statistics; additional laboratory uncertainties of i 6 to 10% have not been propagated into these data. CCalculated, based on U-234/U-235 activity ratio of 26. 9}}