ML20135B799

Discusses Concerns Re Final Radiation Survey of Haul Road Corridor, Submittal

ML20135B799
Person / Time
Site:	07003073
Issue date:	11/25/1996
From:	Lux J KERR-MCGEE CORP.
To:	Brown S NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
NUDOCS 9612060046
Download: ML20135B799 (6)

Text

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h KERR-McGEECORPORMION KERR-McGEE CENTER e ONLAHOMA CITY. OKLAHOMA F3125 November 25,1996 Mr. Stewart Brown Low-Level Waste & Decommissioning Projects Branch Division of Waste Management Office of Nuclear Materials Safety & Safeguards U. S. Nuclear Regulatory Commission Washington, D. C. 20555 i

Re:

Docket No. 70-3073 License No. SNM-1999 i

Dear Mr. Brown:

Kerr-McGee Corporation (KMC) submitted Final Radiation Survey of Haul Road Corridor NRC in May,1996. The Oak Ridge Institute for Science and Education (ORISE) subsequently performed a confirmatory survey of the area. The survey, ORISE's confirmatory survey, and KMC's responses to NRC comments on tha final survey report confirmed that this area is releasable under existing criteria. NRC concurred with this analysis in a letter dated October 22,1996, and released KMC from radiological monitoring and procedural requirements in this area. However, NRC did not release these areas from license SNM-1999, citing three concerns-Potential subsurface contamination, Migration of licensed material from RMAs into the haul road corridor, and Potential groundwater contamination.

The purpose of this letter is to address those concerns.

Potential Subsurface Contamination KMC has identified three factors related to the potential for subsurface contamination:

buried rubble from demolished licensed facilities, vertical migration from surficial contamination, and spots exhibiting elevated exposure rates in the 1990 radiological characterization survey.

Buried rubble was released under the supervision of the Oklahoma Department of Environmental Quality (ODEQ), at that time part of the Oklahoma State Department of Health. KMC described the survey procedure in its response to NRC comments on the final survey report. The rubble was releasable for unrestricted use and does not represent potential contamination.

9612060046 961125

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PDR ADOCK 07003073

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PDR HAULROAD.NRC 1

e Surficial soil samples were collected from the top 15 cm (6 inches) for the final survey of the haul road corridor. All licensed material discovered in the haul road areas was thorium, which adsorbs strongly to the clayey soils present at the Cushing site.

Although there was no reason to suspect vertical migration of thorium from surficial soils, subsurface soil samples were collected from three locations. This work was performed during the delineation of areas of elevated activity. The attached summary of the subsurface investigation shows there was no evidence that licensed material migrated vertically into subsurface soils. Since this data was collected from areas where the potential for subsurface contamination by vertical migration was greatest, there is no reason to believe migration of licensed material from surface sources is occurring elsewhere in the haul road corridor.

The radiological characterization survey conducted in 1990 and reported to the ODEQ in 1991 consisted of exposure rate measurements taken on a ten meter grid over the entire site. Several areas exhibiting greater than 15 pR/hr were located in haul roa i areas. Anecdotalinformation indicated that most of these areas of elevated exposure rates were due to naturally occurring radioactive material, such as firebrick. However, one spot containing thorium in excess of the Branch Technical Position (BTP) Option 1 limit was identified. Surficial soils were removed, and the area was resampled and found to meet release criteria. This data was reported in KMC's response to NRC comments on the final survey report dated August 30,1996.

KMC is confident that its survey and testing for subsurface contamination support the conclusion that there is no reason to withhold release of these areas from the license.

Absent some evidence to the contrary, NRC should not use this concern as a reason to impede the release of these areas from the license.

Niigration of Licensed Material From RMAs into the Haul Road Corridor Radioactive Materials Areas (RMAs) were delineated by scanning surveys of areas indicating elevated activity. Suspect areas were identified in both the 1990-1991 survey, and from subsequent sampling and surveying of the site for site characterization. RMAs extend beyond the area containing licensed material above the BTP Option 1 limit to ensure that there is an adequate " buffer zone" around all soils that will require decommissioning. In addition, the outer perimeters of RMAs near the haul road area support a good vagetative cover. The vegetation prevents migration of licensed material by transportation of soil particles by wind and water. Except for RMA-11, the licensed material in these RMAs consists exclusively of thorium, which sorbs strongly to the clayey soils at the Cushing site and is not likely to migrate via a surface water pathway. RMA-11 contains both uranium and thorium, is separated from the haul road corridor by approximately 500 feet of dense grass cover.

KMC is confident that there is insignificant potential for licensed material to migrate from RMAs to the haul road corridor. Absent some evidence to the contrary, NRC should not use this tencern as a reason to impede the release of these areas from the license.

HAULROAD.NRC 2

j

Potential Groundwater Contamination KMC, NRC, and ODEO met at the Cushing site in January,1996 to discuss the radiological characterization of groundwater at the site. NRC and ODEQ jointly agreed upon a concept which was forwarded in a work plan entitled, Workolan. Evaluation of Licenseo Materials Micration via Groundwater Pathways. submitted October 23,1996.

Although this report was so recently submitted, the concepts contained therein have been accepted by NRC and ODEO tor nearly a year. Key to the groundwater characterization plan is the concept that, for thorium contamination, sampling of subsurface soil beneath areas of elevated activity may validate the contention that thorium has not impacted groundwater from all RMAs except RMA-3, RMA-10, and RMA-11. RMAs 3 and 10 are not hydrologically upgradient from haul road areas, so potentially contaminated groundwater would not affect the haul road areas.

Acid hydrocarbon sludge pits have been present at the site since the 1940s. Migration of non-radioactive contaminants from the acid sludge pits has been shown not to extend more than 25 feet vertically from the pits. Groundwater discharges laterally to topographic surface drainage pathways. Licensed material present in the trash dump, which is less mobile than the acid in the sludge pits, has only been present since the 1960s. It is not reasonable to assume that licensed material could migrate over 300 feet (3-10 times as far as acid-impacted groundwater has migrated) in far less time.

Absent some evidence to the contrary, NRC should not use this concern as a reason to impede the release of these areas from the license.

If you have any questions or comments regarding these responses or the attached information, please call me at (405) 270-2694.

Sincerely, Jeff Lux Project Manager xc:

C.L. Cain, NRC Region IV Rick Reiley, Cushing Citizens' Oversight Committee Gene Smith, ODEQ Darrell Shults, ODEO HAULROAD.NRC

O SUBSURFACE SOIL INVESTIGATION HAUL ROAD CORRIDOR FINAL SURVEY Subsurface soil samples were collected from the haul road corridor from locations with the maximum potential for migration to the subsurface. Historical site photographs show a refinery road running in a north-south direction through the eastern portions of blocks 40 and 52. It is possible that there was a bar ditch or drainage swale on the side of that road that could have received thorium contaminated wastewater. There is a line of elevated radiological readings running along that approximate route. Analysis of surficial soil samples show that the only identifiable licensed material is thorium.

At one location, Block 52-East 80-South 10, a " hot spot" containing greater than 3 times the guideline value of thorium was identified. A ten-meter square was fenced and posted as a radioactive materials area. Because this sample location was in a radioactive materials area cut out from final survey unit 52A, surficial soil activity at this location was not included in Ena!

Radiation Survey of Haul Road Corridor.

Several other soil samples yielded in results in excess of the BTP Option 1 limit. The maps included in Appendix B to Final Radiation Survey of Haul Road Corridor show the locations of soil that exceeded the limit. The level of contamination that exceeds Option 1 limits extends no more than two meters in width and progresses along the drainage ditch in a north-south direction.

KMC considered the greatest potential for subsurface migration of licensed material to exist beneath the centerline of the drainage swale. Three sample locations along this centerline, where the concentration of licensed material exceeded the limit, were selected for subsurface sampling. Soil sampies were collected at 1/4 meter intervals to a depth of 1 meter. The sample locations, depths, and multiple of Option 1 limits follow.

FRACTION OF LIMIT WITH DEPTH LOCATION Surface 0.25 M 0.5 M 0.75M 1.0M i

Block 52-East 80-South 9 1.81 0.22 0.01

-0.09

-0.08 Block 52-East 71-South 70 1.47 0.13

-0.01 0.03

-0.14 Block 40 East 86-South 95 1.42 0.04 0.17

-0.04 0.02 Some of the fraction-of-the-limit values are negative because mean background values were subtracted from soil count data, resulting in some negative net concentrations. Examination of the data shows that for the two samples that exceed 10% of the limit, the driving factor is the U-234 concentration, which is a calculated value based on U-238 and U-235 concentrations. For concentrations so near background, the U-234 calculation is unreliable because the v.wriability in enrichment appears large even when the uranium is natural.

The data clearly indicates that licensed material does not extend more than 0.25 meters (9 inches) below the surface. Contamination is confined to the shallow surficial material only.

HAULROAD.NRC

o Soil Samole Database 6

MGA Sample ID Wex2ht Djgc_h Egg Sm@ Sample DesgptTD DePh U 234 U-235 U-236 Th-232 Ra-226 Option Analysis t

in arams gGyg ECJLq pCV.g gCyg gQjlg Qaiptt t

3 04246078 26 52 71 70 SS2B52E71 S70-0-U.D.

0 8 60 0.36 4 77 6 98 1.72 4'3096 Count Time in Sec.: 300

(+/-)2 sipez Uncertainty 0.27 2 67 0.64 0.80

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3 05026005 32 52 71 70 SOB 52E71S70.25-U D.

0.25 6.90 0 26 0.73 1.09 1.00 5696 Count Tune in Sec.: 300

(+/-)2 sigma lheertainty 0.14 1.20 0.28 0.39 3

05026006 31 52 71 70 SOB 52E71570.5-U D A 0.5 2 06 0 09 1.96 1.01 0.54 5/696 Count Time in Sec.: 300

(+/-)2 sigma Uncertainty 0.16 1.49 0.33 0 46

-3 05026007 33 52 71 70 SOB 52E71S70.75-U.D.

0.75 5 57 0.19 0 00 0.93 0.34 5696 Count Time in Sec.: 300

(+/-)2 segma Uncertainty 0.17 0.21 0.31 0.46 3

05026008 35 52 71 70 SOB 52E71570-1-U.D A.

1 1.23 0 04 0.02 0 85 0.49 5696 Count Twne in Sec.: 300

(+/-)2 sigma Urcertainty 0.16 1.42 0.34 0.48 3

04246123 27 52 80 9

SS2B52E80S9-0-U D.A.

0 7.91 0.30 1.44 7.46 1.59 4/30,96 Count Time in Sec.: 300

(+/-)2 sigma Uncertainty 0.33 3.24 0.81 1.01 3

05026001 29 52 80 9 SOB 52E80S9.25-U D A 0.25 7.87 0.31 2.06 1.16 0 80 5596 Count Tune in Seca 3re

(+/-)2 sgma Uncertainty 0 20 1.76 0.39 0.55 3

05026002 32 52 80 9 SOB 52E80S9.5-U.D.A.

0.5 3.52 0.13 0.35 1.12 0 59 5693 Count Time in Sec.: 300

(+/-)2 sigma Uncertainty 0.19 1.64 0.39 0.54 3

05026003 31 52 80 9 SOB 52E80S9.75-U.D.A 0 75 0 00 0 01 1.81 0.99 0.73 S'6/96 Count Trne in Seca 300

(+/-)2 sigma Uncertainty 0.17 1.75 0.41 0.58 3

05026004 28 52 80 9 SOB 52E80S9-1-U.D.A.

1 0 53 0 03 0.72 1.13 0.82 5696 Count Time in Sec.: 300

(+/-)2 sgma Uncertainty 0 21 1.97 0.48 0.67 i

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Soil Samole Databasg M_GA Samole ID Weicht _ Block Egg. Egyth Samole Descrioton Depth U-234 U-235 U-238 Th-232 Re-226 Option Anahms h*'"'

RGEG RCV9 RCMB.

ECEE a9fs Dalt i

t 3

04086009 23 40 86 95 SOB 40E86S95-0-U D.A 0

0.00 0.00 0.00 8.20 1.02 4/12,96

~

Count Time in Sec.: 300

(+/-)2 sigma Uncertamty 0.61 0.61 0.65 0.85 3

04256040 17 40 86

'95 S40840E86S95-0-U.D.

0 1.12-0.06 2.43 3.70 0.94 5/1/96 Count Time in Sec.: 300

(+/-)2 sigma Uncertainty 0.33 3.18 0.74 0.97 I

3 05026009 32 40 86 95 SOB 40E86S95.25-U D.

0.25 5.85 0.23 1.70 0.63 1.46 5/696 Count Time in Sec; 300

(+/-)2 sigma Uncertamty 0.17 1.48 0.33 0.49 3

05026010 32 40 86 95 SOB 40E86S95 5-U.D A 0.5 5.54 0.21 1.23 1.41 0.58 S$96 Count Time in Sec.: 300

(+/-)2 sigma Uncertainty 0.22 2.03 0.46 0.62 3

05026011 32 40 86 95 SOB 40E86S95.75-U.D.

0.75 0.55 0 05 2.86 0.97-1.12 515/96 Count Teme in Sec.: 300

(+/-)2 sigma Uncertainly 0.22 2.21 0.49 0.70 3

05026012 32 40 86 95 SOB 40E86S95-1-U.D A.

1.

3.45 0.14 0.99 1.09 0.87 S 15/9 6 Count Time in Sec.: 300

(+/-)2 sigma Uncertamty 0.14 1.23 0 29 0.41 t

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