ML20133D755

Provides Environ Survey & Site Assessment Program'S (Essap) Comments Re Review of Fsv Nuclear Station Decommissioning Project Final Survey Rept

ML20133D755
Person / Time
Site:	Fort Saint Vrain
Issue date:	08/14/1996
From:	Abelquist E OAK RIDGE ASSOCIATED UNIVERSITIES
To:	Fauver D NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
NUDOCS 9701100056
Download: ML20133D755 (5)

Text

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M ro-as7 OR1SE OAM ItsOGE sNgrif Uf f FOR LCIE NC E AP 4D E DlX.' AflON August 14,1996  ;

l Mr. David Fauver l Division of Waste Management - NMSS l I

U.S. Nuclear Regulatoly Commission Two White Flint North T-8F37 j

!1555 Rockville Pike Rockville, MD 20852 l

SUllJECT: DOCUMENT REVIEW-FORT ST. VRAIN NUCLEAR STATION DECOMMISSIONING PROJECT FINAL SURVEY REPORT (VOLUMES 1 TIIROUGil 5), FORT ST. VRAIN, PLATTEVILLE, COLORADO (DOCKET NO. 50-267, RFTA NO. 96-05)

Dear Mr. Fauver:

The Environmental Survey and Site Assessment Program (ESSAP) of ORISE has reviewed the subject documentation and offers the attached comments for your consideration. Specifically, ESSAP 1 reviewed the final survey documentation for adherence to survey procedures, conditions that initiated investigations and how these investigations were resolved, and to ensure survey results satisfied the release criteria.

I Please direct any questions or comments to me at (423) 576-3740 or W. L. (Jack) Beck at (423) 576-5031.

Sincerely,

~ , ,

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ywA-U Eric W. Abelquist Assistant Program Director Environmental Survey and Site Assessment Program EA:dka Enclosure

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cc: L. Pittiglio, NRC/NMSS/TWFN R. Uleck, NRC/NMSS/TWFN 7F27 ,hfh j l

D. Tiktinsky, NRC/NMSS/TWFN 8 A23

[ W. Beck, ORISE/ESS AP File /621 i 030047 P. O. BOX l17. OAK RIDGE, TENNESSEE 37831 0117 Managed and operoved by Oak Ridge AssocioW Un.versities for the U.S. Department of Energy 9701100056 960814 ADOCK 05000267 PDR W PDR

Comments Fort St. Vrain Nuclear Station Decommissioning Project Final Survey Report (Docket No. 50-267, RFTA No. 96-05)

General Comments In general, the final survey report (Volumes 1 through 5) adequately describes the survey methodology and instrumentation that was used for the FSV decommissioning project (a few exceptions are noted below). The site description, survey unit operational history, and decommissioning activities provide detailed information on the radiological status of the site. The results of the survey unit investigations performed during the final survey were generally complete and provided adequate resolution. Furthermore, the licensee commonly performed investigations to evaluate anomalous data, even though specific action levels for investigation had not been exceeded.

Licensee conclusions regarding survey unit compliance with release criteria were clearly stated.

The frequency of sampling for hard-to-detect-nuclides (HTDN) in suspect affected areas appears to be very minimal, especially for Fe-55, which comprises the majority of the residual radioactivity at the FSV facility-it was ESSAP's understanding that some frequency of sampling for HTDN would be performed in affected areas, yet it appears that only a few survey areas discuss HTDN.

Furthermore, it is unclear what HTDN sample results are compared to-the surface activity guidelines for H-3 and Fe-55, or the radionuclide mixture determined by the sampling campaign in 1994, or both. It is recommended that the comparison criteria be explicitly stated for HTDN samples and that the results of sample analyses used for determining radionuclide mixtures be provided.

Soil and miscellaneous samples have been collected in some survey units as support for demonstrating that the release criteria have been achieved. Because release criteria for soil concentratio- have not been established, the licensee has demonstrated compliance by stating that licensable radio "ity was not present in these samples. What specific licensable radionuclides were considered when stating that only naturally occurring radioactivity was present? It is recommended that the licensee state the minimum detectable concentrations (MDCs) for each of the possible contaminants so that they may be compared to soil guidelines-once they hr.ve been proposed by the licensee and accepted by the NRC.

The licensee's equation for determining the MDC for surface activity measurements may not be appropriate, considering the manner in which they calculate the surface activity. The equation that the licensee uses accounts for the uncertainty in the background level by assuming that the only sourm oferror is due to counting statistics. Because the licensee defines the background as the sum of tw :omponents-the material background and the local area background-the uncertainty in the background should include a complete assessment of the uncertainties associated with the determination of the background. That is, the decision on the presence of residual surface activity is based on a comparison of the unshielded detector response to the sum of the material background

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and the local area background. For example, the licensee calculates the background using an equation

'similar to the following:

BKG = Ry + A,,

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• 100 The uncertainty in the background not only includes the counting error in R., but also the error in the determination of the material-specific activity (A,J and in the detector efficiency, E.

It appears that the licensee used the same equation for the determination of the scan MDC as that used for the static direct measurement MDC. It is recommended that additional information be provided on the implementation of the scan MDC equation; specifically, the selection of t, and t., and how they relate to the scan rate.

Attachment 2 of Volume I contains the results of the independent verification survey performed by GPU Nuclear Corporation. Page 3 of the Attachment states that " surveys ... produced results which were consistent with the findings of the on-going final survey performed by ...SEG." Were statistical evaluations performed on the SEG and GPU data sets to support the conclusion that results were consistent? A limited review of the total activity results reported by SEG and GPU, for the same location, appear to be significantly different in some locations. For example, in Room 1019 (page

18) the GPU total activity is consistently lower than the SEG data, sometimes by as much as a factor of 20 at a specific location. In contrast, the GPU total activity results on Level 7 of the Turbine Building (page 38) are consistently higher than the SEG data by approximately a factor of 5. Have discrepancies between the SEG and GPU data sets been investigated?

The resolution for many investigations concerning exposure rates greater than 5 pR/h involved the use of the Nal-based MICROSPEC system to demonstrate that licensed material was not present and therefore, did not contribute to the measured exposure rate. Has the licensee performed an assessment of the minimum detectable exposure rate achievable with the MICROSPEC for the major contaminants present at FSV? Also, have any comparisons been performed between the MICROSPEC and a Ge detector in the evaluation of these elevated exposure rates to assess the MICROSPEC's performance-e.g., can the Ge detector system detect licensed material at significantly lower levels than the MICROSPEC7 Soecific Comments

1. Volume 1, page 6 It appears that a discrepancy exists between the summary Table 6.3 and Table 3.1 of Volume 2. It appears that the maximum and upper confidence level (UCL) for exposure rate measurements in Survey Area A0001 should be 5.5 and 1.7 pR/h, j respectively.

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2. Volume 2, A0007, p. 72 - The summary section for beta scans states that no areas of elevated activity were identified; however, the following statement is made in the survey unit investigations section: " elevated count rates were identified...during the scan portion of the initial final survey." Please clarify this apparent discrepancy.

3. Volume 2, A0011 - The survey unit investigation section discusses a small elevated area that was identified in the Visitor's Center. Was this elevated area due to natural activity from the display case, or was this licensable activity?

4. Volume 3, B0009, p. 35 - The first six locations exhibit surface activity levels ranging from

-349 to -762 dpm/100 cm 2-it appears that an improper medium background has been subtracted to bias these measurements low. It may be that a similar situation was identified in Survey Area C0004, page 7, where the resolution was to change the material background to generic material. A similar resolution was applied to Survey Area C0012, page 7, where it was suspected that bare concrete in this survey unit was different than that for which a 2

material background of 767 dpm/100 cm was determined.

5. Volume 3, B0012, p. 43 - The statistical summary for tritium removable surface activity measurements states that further investigation is needed because the MDA is not less than 187.5 dpm/100 cm2 . Where will this investigation be documented?

6. Volume 3, B0012, p. 74 - The survey design section states that tritium smears are collected at approximately 5%)of the survey measurement locations for beta-gamma smears; however, only 8 tritium srheafs (2.5%) were collected. Please explain this discrepancy. Furthermore,{

what was the rationale for not performing an Fe-55 assessment in this survey unit-did thel smear collected on 4/20/94 from the Helium Storage Building indicate the presence of Fe-557!

7. Volume 3, B0015, pp.12 to 16 - Approximately 70% of the surface activity measurements in this survey unit are negative-it appears that an inappropriate background subtraction was use6 on this data set. As mentioned in comment #6, it is not clear why an assessment for HTDNs was not performed-the machine shop was used to perform work on contaminated valves and fuel handling devices.

8. Volume 4, C0002, C0008, C0011, and C0023 - Approximately 70% of the surface activity measurements in each of these survey units are negative-it appears that an inappropriate background subtraction may have been used on these data sets.

9. Volume 4, C0011 - Page 9 and 10 of this Survey Area appear to have exactly the same information.

10. Volume 4, C0013 - It is recommended that the surface activity levels for the 6 elevated areas l be specified, as well as providing their location.

I l 1. Volume 4, C0016, p. 2 - Typo: Should be 2 survey units, not 4 survey units.

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12. Volume 4, C0030 and C0052 - It is recommended that the elevated areas identified by the surface scan remain in these data sets. The explanations provided in the survey unit i investigations do not support the deletion of this surface activity value. It does not seem  ;

appropriate to delete data that was identified by a scan survey and then confirmed by direct measurements of surface activity. The data set should reflect that small, isolated elevated l areas remain and that compliance with release criteria is still maintained. l i

13. . Volume 4, C0031 - The survey design summary states that no areas of elevated activity were detected. This is apparently contradicted by the survey unit investigation section which states ,

that an elevated area (3381 dpm/100 cm2) was identified by the surface scans.

14. Volume 4, C0033 - Although not it does not exceed the threshold for investigation, was l location #173 investigated to assess whether removable activity levels in this immediate area were greater than the 79 dpm/100 cm2 level reported.

15. Volume 4, C0058, p. 6 - It is not clear whether the one elevated area identified by surface scans was the initial elevated area that triggered the reclassification of this area, or if an ,

elevated area was identified during the survey of C0058.

16. Volume 5, D2500 - What is the laboratory protocol for analyzing H-3 and Fe-55!

together-or are they analyzed separately and the activities summed? Was the combined H-2 and Fe-55 activity compared to the 40,000 dpm/100 cm limit for removable surface activit  !

to demonstrate compliance?

17. Volume 5, D3300 and D5500 - The data indicates that removable activity was not assayed for Fe-55-if that is the case, then the discussion on page 3 should not include Fe-55.

18. Volume 5, D4800 - It appears that Fe-55 analysis was not performed, although it was ,

l mentioned in the survey design section. It is recommended that ajustification be provided ;

for the collection of only one special sample in this affected system, and then apparently not j analyzing the sample for Fe-55.

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