ML20217G250

Forwards Response to 970819 RAI Re Survey Repts of Hot Laboratory Support Bldgs & Outdoor Areas Inside & Outside of RCA

ML20217G250
Person / Time
Site:	05000054, 07000687
Issue date:	10/08/1997
From:	James Adler CINTICHEM, INC.
To:	Dragoun T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
NUDOCS 9710090285
Download: ML20217G250 (11)

Text

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CINTICHEM, INC. -

P.O.' BOX B18

' TUXEDO, NEW YORK 10987 i914] 351-2131 October 8,1997 hir. Thomas Dragoun U.S. Nuclear Regulatory Commission Region 1 475 Allendale Road King of Prussia, PA 19406

Subject:

Cintichem Final Survey Plan and Report Sections 11 to 18 s

Dear hir,

' Dragoun:

This submittal is in response to an NRC letter, dated August 19, 1997, requesting additional information on the survey reports of our Hot Laboratory Support buildings and their outdoor areas inside!outside of the RCA. I have attached Cintichem's responses to those inquiries. '

If you have any further comments or questions, please contact me at (914) 3512236.

4 Very truly yours, '

4%IA.--

-A.J. W Joseph J. Adler-COOC33 hianager, HS & EA Enclosure, as stated J, y O i

cc: E. Abelquist, ORISE C. Warren R. Aldrich, NYS L. Feigenbaum B. Youngberg, NYS J. hicGovern {-

I T. hiichaels, NRC J. Adler D. Orlando, NRC- L. Glander Document Control Desk, NRC bec: F.C. Kentz, III l}\lklh$f!f5!

9710090295 971000 "

PDR ADOCK 05000054:

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Response to Request for Additional Infomatioru Dodsets 50-64 & 70-687 Cintidiem Mnal Survey Plan and Report, Lloenses R-81 & SNM-689 Senians 11 through 18 Page 1 of 9 i --

i i

e L ' 1) In the MDA equations listed, it is unclear if the term under the radical (background)is in units of cpm or counts. If the term is in units of cpm, then this should be stated as background count rate. If the units are counts, then the count time multiplier should be removed. Please review.

! The background term under the radical should be in units of counts per minute, i i.e., background count rate. The instrument MDAs were calculated correctly j using the background count rates.-

4 l 2) Please provide information regarding the NISTtraceable source used for alpha instrument calibration.

i Potential alpha surface contamination due to highly enriched uranium (HEU) j and/or transuranics (TRU) was measured usNg alpha scintillation detectors.

j These detectors were calibrated using a NIST-traceable Uranium 234/235 source 8

i (s/n: 92USP001195). This source consisted of a 100 cm stainless steel plaque upon which the uranium was electroplated. This source had an activity of 7720 dpm per 100 cm'. This calibration applies to the direct alpha contamination l

measurements speciGed in Sections 11,13, and 15 of the Final Survey Plan.

p 3). In regards the equatior used to convert instrument field readings from cpm to dpm /100cm'.-

a) It is stated that readings are corrected for instrument background but not -

material natural background unless the natural background is sufficiently high as to interfere with achieving releasable levels. If the material background was subtracted, what correction was made toprevent subtracting instrument background twice in this calculation?

Instrument background was only subtracted once, whether or not material natural background was accounted for. If a material's natural background were to be subtracted, the material background to be subtracted would be determined by taking a measurement on a backgrou'nd surface and subtracting the instrument background from it. The instrument background consists of an "in air" measurement, without the detector in contact with any surface. As such, for a gross measurement result to be corrected for its natural radioactivity content, it would first have the instrument background subtracted. This result would then have the material background subtracted, less the instrument background, as follows:

, - - - - - , - = . . . - , - . _ , . - , - ~ .. ,, .-- n

e Response to Request for Additional Informatioru Dodcets 50-54 & 70-687 Cintichem Final Smvey Plan and Report, Lloenses R-81 & SNM-639 Sedians 11 tluuugh 18 Page 2, ct 9 i

(gross sample count rate) - (instrument bckgnd rate * ) =

< net sample count rate, uncorrected for material background (net count rate) - (gross material bkgnd count rate ** instrument bckgnd rate *) =

net sample count rate, corrected for material background 4

4 Instrument background measurement count rate "in air"

• • Instrament count rate on contact with a background material i

b) In many survey units, mean and true values for direct beta and alpha contamination are negative. Ifmaterialnatural backgroundis not subtracted from gross counts, then mean values should almost always be positive.

Please explain the causes of negative mean values.

Background levels at the Cintichem site vary significantly by location. The most significant factor in this variation is the proximity of bedrock which contains natural deposits of uranium and thorium. Many of the survey units

. consist of three dimensional arrays of surfaces, such as overhead steel structural members, where the orientation of the detector is constantly changing (i.e., facing the top, the side, or the bottom of an I beam). When a significant portion of the background comes from one direction (i.e., the-bedrock below), some of the readings may be fully or partially shielded from this background source by the surface in question. Additionally, measurement locations within a survey unit can vary in distance from a significant source of background; that is, the top of a wall could be further from the bedrock than the bottom of a wall. As such, determining an analogous background level under these conditions, whether for a single point or an entire survey unit, is at best an estimate, where the distribution of measurement locations can affect the outcome.

In addition to there being survey units with negative means, it is also true that there are likely to be survey units with overly positive results caused by similar background anomalies.

4) NRC calculations of survey unit contamination limits using the " unity" rule concept and appropriate mix of isotopes resulted in higher values than were calculated by Cintichem. Please describe any additional factors used in your calculations.

Cintichem has recalculated the contamination limits (Hot Lab Mix) using the isotope mix reported in the Final Survey Plan within the " Identity of Contaminants" section. The results (1275 dpm/100 cm2 ) are essentially equal to

Response to Request for Additional Infcastation: Doakets 50-54 & 70-687 Cintkhem Final Survey Plan and Report, Licenses R-81 & SNM-639 Sedions 11 through 18 Page 3 of 9 those presented in that section of the Plan (i.e.,1273 dpm/100 cm2). The 0.16%

difference is due to rounding. Cintichem dces not know why NRC calculations resulted in a higher limit. The following is Cintichem's calculation for the average turface contamination limit of the Hot Lab Mix:

DAl2X + 0.216X + 0.0026X + 0.00419X + 0.0181X + 0.0025X +

5,000 5,000 200,000 200,000 5,000 5,000 (Ce144) (Cs 137) (Fe 55) (H 3) (Ni 63) (Ru 106) 0.00420X + 0.732X + 0.00151X = 1 5,000 1,000 5,000 Solving for X :

(Sb 125) (Sr 90) (Tc-09) X = 1275 dpm/iOO cm' l 5) Statements in " Survey Plan" sections indicate that scans were not performed in l the unaffected areas. NUREG2R 5849 recommends that scans should be performed on 10% of unaffected floor and lower wall surface areas and 10& of una."ected open land areas. Please provide a rationale for not performing scans in accordance with NUREG2T 5849.

Scanning of unaffected structural surfaces was not performed for two reasons: i

1) The MDA's for scanning the hot laboratory mix anu the uranium ore mixture is greater than the release criteria and, as such, may not detect a contaminated surface. The scanning MDA's are 2880 and 7000 dpm/100 cm2, respectively, for the hot lab and ore mixtures -- approximately two times the release criteria. Therefore, scanning would not produce useful information.

2) Cintichem's final survey experience indicates that when contamination was found on surfaces thought to be unaffected, it tended to be homogenous or widespread enough that most, if not all, of the 30 sample points had indications of elevated activity.

It should be noted that a very small fraction of the Hot Laboratory Building's interior was surveyed on an unaffected area basis. These were mostly of miscellaneous horizontal overhead surfaces, such as overhead I beams, railings, or cabinet tops, where airborne dust settling would produce a relatively uniform layer of contamination (see also the answer to question number 11). A similar situation is also true for Building Three, where most of the contaminated surfaces found outside of the known ore processing area were due to deposition of airborne dust which produced uniform layers of contamination.

Response to Request for Additional Infonnation: Dodmts 50-54 & 70-687 Cintiaem Final Survey Plan and Report, Licerses R-81 & SNM-639 Sedians 11 through 18 Page 4 of 9 Land measurements outside of the former RCA were all treated as affected areas except survey units 500.2 and 500.3. These areas, as well as some other i unaffected site land areas, were actually scanned with a 2x2 Na1 detector as technicians moved between the random sample points. The resulting data was found to be extremely misleading, where false indications of elevated activity were constantly encountered. This was largely due to the extreme Gactuations caused by natural radioactivity in rock ledges and boulders. This was confirmed by soil sampling and in situ gamma spectroscopy measurements which detceted only natural radionuclides.

6) A footnote to the soil release criteria tables indicate that isotopes of Uranium and Plutonium will not be included in the sum of fractions calculations. In a letter dated June 8,1995, NRC staff stated that this was inconsistent with the coil criteria approved by the NRC staffin August 1993 and stated that, if these

, radionuclides were found at the site, Cinticheu should contact the NRC staff to discuss the issue further.

In a letter dated April 3,1997, from Barbara Youngberg to James McGovern, the New York State Department of Environmental Conservation stated that the uranium ore found in the area of the Cintichem facility referred to as the " Union Carbide Spoils Area" was licensed by NYSDEC and therefore subject to regulatory oversight of NYSDEC. NRC staff concurred with NYSDEC in this determination. Therefore, Cintichem should contact NYSDEC to de: ermine the appropriate manner in which the radionuclides should be managed.

However, Cintichem is requested to confirm that no Uranium or Plutonium subject to the NRC-approved soil release criteria has been detected.

Cintichem agrees that uranium and plutonium radionuclides, if detected, should

be included in the sum of fractions calculations. However, uranium and

, plutonium radionuclides subject to NRC-approved soil criteria have not been found in soil on site and, as such, the outcome of the soil's final surveys will not i change. Uranium ore parent radionuclides (i.e., U-238, U-235, and Th 232) will

be compared to criteria using the sum of fractions rule.

7) The table " Instrumentation Used for Radiological Survey Activities" lists instrument identification numbers as 1 to 10. Survey data sheets record the j instrument identification as "12," "A,"and other designations. Please explain.

The instrument identification designators on the survey data sheets were not intended to correspond to instrument list numbers. The instrument designators on the survey data sheets are used to identify and differentiate instruments of

'l

Response to Request for Additional Information: Dockets 50-54 & 70-687 Cinti&cm Final Smvey Plan and Report, Licenses R-81 & SNM-639 Sodions 11 thrc:gh 18 Page 5 of 9 the same type. This is done so that (1) the data spreadsheets can perform data conversions using instrument-specific efficiencies, and (2) data can be linked to a specific individualinstrument for quality assurance purposes. As can be seen from the data sheets, sometimes more than one of each type of instrument is used for a particular survey unit.

8) In summary results tables, is the row labeled Due Mean: U alpha 95% C.L."

equivalent to mu subscript alpha described in NUREGER 5949?

Yes.

9) In the tables presenting " soil data for sum of the fractions," plea,.c describe the method of obtaining entries under columns labeled ' isotopes of concern in fraction of limit," " sum,"and " grid block avg. fraction oflimit."

The entries under the column " Isotopes of Concern in Fraction of Limit" are obtained from individual gamma spectroscopy or Sr 90 aralysis reports. These entries are manually entered into the spreadsheets. Tne raw gamma spectroscopy data, in terms of count rate for an identified peak are converted to conce'ntration using the EG&G ORTEC Omnigam software package. Raw Sr 90 results are converted by spreadsheet calculation by Cintichem or Teledyne, depending on which laboratory was used. MDA values are also calculated by these software packages or spreadsheets using the formulae specified in NUREG 5849. The term " Isotopes of Concern" refers to those radionuclides that have been found in Cintichem's site soil and that can contribute significantly to the sum of fractions tally. During the decommissioning process soil was routinely analyzed for the presence of radionuclides for which nriteria was developed, such that those not reported have been reasonably ruled out from being present.

Entries listed under " Sum" consist of the sum of fractions result for each individual soil sample. This sum represents the fraction of the maximum hot spot criterion (i.e., three times the average soil concentration guideline). The

" Sum" entries are calculated by summing the detectable concentrations of each radionuclide that have been divided by 1 hree times its average soil concentration guideline.

Entries under " Sum Grid Block Avg Fraction of Limit" represent the comparison (i.e., sum of fraction) of the mean of all soil sample results (from within a ten by ten meter grid box) to the average soil concentration guidelines. The data on the data spreansheets are grouped by grid-block. The entries under this column are

• calculated by determining the mean concentration for each radionuclide from all of the systematic samples taken within the grid block. Each mean radionuclide l

Response to Request for Additional Information: Dockets 50-54 & 70-t387 Cintkhem Final Survey Plan and Report, IJoenses R-81 & SNM-639 Sedians 11 tluough 18 Page 6 of 9 concentration is then divided by the average concentration guideline and the results are summed, 1 10) If any soil " hot spots"were accepted as the result of an evaluation of the area averaging methodology outline in NUREG2R 5849, i.e., the volume activity of the soil did not exceed the average by more than V(100bt), please provide these calculations.

Soil"liot spots" were found within 17 soil grid boxes. Five of these grid boxes are within very rocky areas consisting of mostly boulders and very little soil.

Of these five areas, one exceeds the mean soil criteria. All of the hot spots are less than three times the soil criteria. However, they do not meet the criteria for hot spot size (i.e, V(100/A)). These five areas are as follows:

Hot Spot Hot Spot Orid Box Mean Coordinates Sum of Fractions

• Sum of Fractions l 1. 122.5 N x 12.5 E 2.3 127.5 N x 12.5 E 1.69 122.5 N x 17.5 E 2.6 1.63

2. 132.5 N x 12.5 E 1.73 137.5 N x 12.5 E 1.55 0.93

3. 122.5 N x 22.5 E 1.04 127.5 N x 22.5 E 1.51 0.87

4. 137.5 N x 22.5 E 1.91 0.76

5. 242.5 N x 37.5 E 2.41 0.49

• as compared to the mean soil criteria These areas are within survey populations that have been extensively remediated and very little soilis left in these five areas. The resulting ground surfaces are mostly rock boulders with small amounts of soilin between them.

Therefore, these five areas do not conform to the scenario from which the soil criteria was developed (i.e., the soil limits are too conservative for these situations). Page two of Section 15 of the Survey Report offers additional information on this subject.

The other 12 grid boxes with " hot spots" were found in " normal" soil areas.

These 12 grid boxes meet the criteria for grid box mean sum of fractions, hot spot size (i.e., V(100/A)), and have hot spots less than three times the mean soil criteria. These hot spot areas were bounded by scanning with a scintillation detector and additional soil sampling and/or by extrapolating the hot spot

, _ . . _ . ___ _ _ ~ _ _ . _ _ _ . _ . . _ _ _ __ . . _ _ . . . . . _ _ . _ . . _ _ . _ . . _

~ -

Response to Request for Additional Information: Dockets 50-54 & 70-687 Cintidtwn Final Surwy Plan and Report, Licenses R-81 & SNM-639 Sections 11 tluvugh 18 Page 7 of 9

)

areas out to the nearest systematic sample points. The following presents the results of the hot spot analysis.

Hot Spot Hot Spot Orid Box Mean Hot Spot Max. Hot Spot Coordinates Sum of Fractions Sum of Fractions Ar.ga (m') Size. V(100/A)

1. 17.5 N x 27.5 E 1.11 0.41 s 50 1.41

2. 22.5 N x 32.5 E 1.1 25 N x 35 E 1.23 0.778 5 56 1.34

3. 122.5 N x 47.5 E 1.44 0.44 s 30 1.82

4. 102.5 N x 7.5 E 1.23 0.39 5 50 1.41

5. 125 N x 5 E 1.28 0.56 5 25 2.0

6. 95 N x 25 E 1,41 0.67 5 25 2.0

7. 272.5 N x 62.5 E 1.06 0.3 5 50 1.41

8. 225 N x 2a E 1.26 0.51 5 25 2.0

9. 247.5 N x 62.5 E 1.17 0.4 5 50 1.41

10. 375 N x 65 E 1.9 0.62 5 25 2.0

11. 107.5 N x 75 W

• 1.36 0.39 s 13 1.9

12. 192.5 N x 72.5 W ** 1.19 0.59 2.7 3.6

• Partial grid block ~50 m2

• • Partial grid block ~35 m2; 3 times mean criteria is more limiting 2-10) The text states that a Ludlum 44-9 GM detector was modified to provide access to pigeon holes. Please provide confirmation that the detector size is still 20 cm' andprovide information regarding ihe calibration of this detector.

The detector size was not modified and was still 15.5 cm'. This active detector area was determined using the inside diamter of the GM tube, not the exterior diameter, which would produce a 20 cm2 area. The " pigeon hole" detectors used for Section 11 and 12 final surveys (Hot Laboratory Buildings) were calibrated using a NIST-traceable Sr 90 disk souren. This 14.2 cm2 source (s/n 7032) was manufactured by Isotope Products, Inc. and contained 0.01035 pCi (11-15-93).

Response to Request for Additional Information:

Dcdcets 50-54 & 70-687 Cintidem Final Survey Plan and Report, Limnses R-81 & SNM-639 Sections 11 through 18 Page 8 of 9

11) Survey areas 312, 313, and 314 were affected areas but the hori:ontal and vertical support beams in these areas were classified unaffccted. Please explain.

The survey units designated as " Unaffected" that are within survey areas that are completely "affected" are actually subsets of the affected survey units. As an example, the miscellaneous horizontal and vertical surfaces, consisting of a ceiling's support beam were also included as part of that ceiling's survey unit.

As such, the 100% scan performed on the ceiling also included the I-beam and other miscellaneous surfaces. Additionally, when a systematic survey point (i.e.,

five per 1x1 meter grid box) fell on an I-beam or other miscellaneous surface, that was also included as part of that survey unit. ' As such, the 30 " unaffected" survey unit measurement points area actually extra points added tot he affected survey units within a survey area. These extra survey units were specified so as to rule out a potential bias within the affected survey units, where a different t

distribution of survey points (i.e., changing the number on the underside of ceilings, sides of I beams, or tops of horizontal surfaces) could change the outcome of the survey's conclusions.

12) Please confirm that area 324.01 was not surveyed because all surfaces were removed during remediation.

Survey unit 324.01, the concrete floor of the polishing filter bank, was removed during the remediatien.

13) Why were only 26 readings taken in survey area 501.3, which has an area of approximately 900 m' ?

The2 area that was reported for the asphalt pad around the storage buildings (900 m ) is incorrect. The footprint of the buildings was inadvertently included. The correct surface area is approximately 520 m2 . The 26 measurement points are reasonable for this area, as shown here:

520 m' x 5 meas. noints .= 26 measurements 100 m'

14) Please describe the release criteria for area 502.4 (drain line pipe) after the unique isotope mix was found.

The 2 release criteria for the interior surface of the drain pipe is 3762 dpm/100 cm . This limit was determined using the sum of fractions rule for the following isotopic mixture:

l c

Response to Request for Additional Infonnation

Dockets 50-54 & 70-687 Cintidiem Mnal Survey Plan and Report, Lloenses R-81 & GNM 639 Sections'11 thmugh 18 Page 9 of 9 4

Fractional Radionuclide _ Abundance Co60 0.0234 Sr 90 0.0982

, Ag 108m 0.0097-l Cs 137 0.8687 The calculation of the average total surface release criteria is as follows:

1

0.0234X + 0.0982X + 0.0097X + 0.8687X =1 Solving for X

! 5000 1000 5000 5000 X = 3762 dpmfl00 an*

j (Co-60) (Sr-90) (Ag 108m) (Cs 137)

This radionuclide mixture was determined from the analysis of sediments that were removed from the pipe during the D&D process. Using the gamma logging process, the release criteria was applied as an average col.tamination level over 8 2 a 2280 cm area (0.228 m ). This area consists of the bottom half of an interval

of drain pipe that is 0.6 meter long, a

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1 i

1 i

4 4

Response to Request for Additional Informatic e Dockets 50 54 & 70-687 Cintichem Final Survey Plan and Report, Limnses R-81 & SNh.-639 SeJPris 11 through 18 Page 9 of 9 Fractional Radionuclide Abundance Co 60 0.0234 Sr.90 0.0982 Ag 108m 0.0097 Cs 137 0.8687 The calculation of the average total surface release criteria is as follows:

0.0234X + h 0982X + 9.0097X + 0.8687X =1 Solving for X:

5000 1000 5000 5000 X = 3762 dpnV100 cm' (Co 60) (St 90) (Ag 108m) (Cs 137)

This radionuclide mixture was determined from the analysis of sediments that were removed from the pipe during the D&D process. Using the gamma logging process, the release criteria was applied as an average contamination level over 2

a 2280 cm' area (0.228 m ). This area consists of the bottom half of an interval of drain pipe that is 0.6 meter long.

.