ML20133E038
| ML20133E038 | |
| Person / Time | |
|---|---|
| Site: | 07000139 |
| Issue date: | 12/06/1996 |
| From: | Abelquist E OAK RIDGE ASSOCIATED UNIVERSITIES |
| To: | Richard Turtil NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| RFTA-97-7, NUDOCS 9701100174 | |
| Download: ML20133E038 (4) | |
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ORISE OAK RIDGE #P4STITU TE FOR SCit t-ACE AP40 ( OtJC ATIOP4 December 6,1996 Richard Turtil U.S. Nuclear Regulatory Commission l
Division of Waste Management - NMSS Ttvo White Flint North T-7F21 11555 Rockville Pike j
Rockville, MD 20852 SUIMECT:
DOCUMENT REVIEW-FINAL STATUS SURVEY REPORT, SURVEY UNITS 1 AND 2 IN INTERIOR OF PLAINVILLE, MASSACIIUSETTS PLANT OF ENGELIIARD CORPORATION (DOCKET NO. 070-139; RFTA NO. 97-7) l
Dear Mr. Turtil:
The Environmental Survey and Site Assessment Program (ESSAP) of the Oak Ridge Institute for Science and Education (ORISE) has reviewed the subject document and offers the attached comments for your consideration. It is recommended that the " Final Status Survey Plan" and
" Responses to NRC Comments on the Plan (September 14,1996)" be provided for ESSAP's review, particularly for information on the development of the surface activity conversion factor.
Please direct any questions you may have to me at (423) 576-3740 or Timothy J. Vitkus at (423) 576-5073.
Sincerely, f
Eric W. Abelquist Assistant Program Director Environmental Survey and Site Assessment Program EWA:tsf 9701100174 961206 I
PDR ADOCK 07000139 g
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Enclosure ec:
R. Uleck, NRC/NMSSffWFN 7F27 D. Tiktinsky, NRC/NMSS/TWFN 8A23 W. Beck, ORISE/ESSAP T. Vitkus, ORISE/ESSAP
/O(1e. File /678
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'JU P. O BOX l17, OAK R!DGE. TENNESSEE 37831-0117 Managed and operated by Ook Ridge Associated Umverohes for the U S Department of Energy l
i COMMENTS FINAL STATUS SURVEY REPORT SURVEY UNITS 1 AND 2 INTERIOR OF PLAINVILLE, MASSACIIUSETTS PLANT ENGELIIARD CORPORATION (DOCKET NO. 070-139; RFTA NO. 97-7)
GENERAL COMMENT
S 1.
In general, the final status survey report adequately describes the survey methodology and instrumentation that was used at the Engelhard plant in Plainville, Massachusetts. The site i
description, operational history, and decommissioning activities provide detailed information on the radiological status of the site. The results of the radiological characterization survey provided information on the nature and extent of the radiological contamination on the site-depleted, natural and enriched uranium. However, it would be beneficial if the enrichment of the uranium was provided-page 5 of the report states," uranium is enriched in U-234 and U-235 above naturally occurring levels." This information is necessary in order to assess the appropriateness of the conversion factor derived for converting measured count rates to surface activity units (dpm/100 cm ),
2 2.
The guidelines for surface contamination, radionuclide concentrations in soil, and exposure rates have been clearly stated. Survey data reduction is consistent with the guidance provided in the U.S. Nuclear Regulatory Commission's (NRC's) NUREG/CR-5849, " Manual for Conducting Radiological Surveys in Support of License Termination," with the exception that the methodology used to develop the conversion factor for determining uranium surface activity was not included in the final status report. ESSAP recommends including this information.
3.
The survey data contained in the tables in Appendix A adequately describe the final status survey results. However, there is some confusion as to the manner in which background surface activity was applied for various surface types to correct the gross counts. The tables should also specify the counting time that was used for surface activity measurements.
4.
It is ESSAP's understanding that the " effective alpha activity", as labeled in the Appendix A tables is the measured quantity that is used to demonstrate compliance with the uranium surface activity guidelines. The effective alpha activity is the measured activity multiplied by the total uranium conversion factor. It is recommended that the minimum detectable activity (MDA) be calculated to yield values comparable to the effective alpha activity. Specifically, the MDAs provided in Appendix A should be corrected by the total uranium conversion factor as well.
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l Engelhard Corporation (678). December 6,1996 h:\\essap\\ reports'engel.001
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5.
ESSAP is concerned with the licensee's use of a large-area detector (425 cm ) to make surface 2
activity measurements. The activity of small areas of contamination-i.e., areas less than 100 2
cm -may be underestimated by using the large-area detector to perform direct measurements.
An example is provided for clarification:
Given:
assume that area of contamination = 100 cm,
2 total uranium conversion factor = 2.5, background radiation level = 1,296 cpm, gross detector response at survey point = 3,208 cpm, and instrument efficiency = 0.23 counts per disintegration.
Total uranium using the licensee's calculational model:
surface activity = 2.5 * ( '
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2
= 4,890 dpm/100cm (0.23) (425/100)
Ilowever, the actual surface contamination level in this example is underestimated due to the "over-averaging" effect of the large-area detector. The maximum contamination guideline 2
applies to an area of not more than 100 cm and averaging surface contamination over a larger area is not in compliance with the surface contamination guidelines. The surface contamination level in this example may be calculated (if the large-area detector is to be used to perform direct 2
measurements and assuming the contaminated area is 100 cm ):
surface activity = 2.5 + (3,208 - 1'296) = 21,000 dpm/100cm *
(0.23) (100/100)
Therefore, the calculational model used by the licensee to report total uranium activity from large-area detector direct measurements may not reflect the conditions at the site.
6.
The description of affected areas on pages 3 and 4 of the report seem inconsistent with the survey unit described in section 3.4.2 (page 10), which in turn is inconsistent with the areas listed as belonging in Survey Units 1 and 2 on page 1 of Appendix A. For example, the affected areas stated on page 3 that have the highest potential for residual radioactivity included the tunnel ramp, room 2L, room 2M, room 2N, room 2H, and room 2B. Page 10 describes Survey Unit I as consisting of areas with the higher measured contamination levels and include rooms 2M,2L,2N, and the tunnel (rooms 2H and 2B appear to be missing). Furthermore,in Appendix A, the note states that Survey Unit 1 includes 2A, entry,2B,2C,2D,2E,2F,2G,2H,2K,2N, and 2P; and Survey Unit 2 includes 2L,2M, and tunnel. It appears that survey unit designations that are given on Appendix A page 1 may have been reversed, but it is still unclear why room 2N isn't included with rooms 2L,2M, and the tunnel.
2 h",essap\\ reports \\engel 001 Enpihard Corporation (678) December 6.1996
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The confusion concerning areas comprising Survey Unit I and 2 made it difficult to validate the final survey statistics in Table A17. It is recommended that the licensee specifically state which areas comprise each survey unit and confirm the summary statistics in Table A17.
l SPECIFIC COMMENTS 1.
Page 13-The report states that "a smear was taken...to validate that both fixed and removable limits had been met." Sentence should be restructured to also state that direct measurements validate that fixed limits had been met (a smear can only assess removable activity).
f 2.
Appendix A survey results-Survey results for the walls in rooms 2F,2N, and 2P exhibit a number of surface activity levels that are negative. It appears that an improper background surface activity has been subtracted to bias these measmements low.
l 3.
Appendix A, Tunnel-The effective alpha activity for survey location Z,0 + 0.5,0 is reported I
as 5,013 2,859 dpm/100 cm. It is recommended that an explanation be provided for this 2
value that exceeds the average surface activity guideline.
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