ML20082B982

Instrumentation Comparison Plan Between Orise & Fort St Vrain

ML20082B982
Person / Time
Site:	Fort Saint Vrain
Issue date:	03/15/1995
From:	OAK RIDGE ASSOCIATED UNIVERSITIES
To:
Shared Package
ML20082B975	List: ML20082B973 ML20082B982
References
PROC-950315, NUDOCS 9504060112
Download: ML20082B982 (2)

Text

C.

INSTRUMENTATION COMPARISON PLAN BETWEEN ORISE AND FORT ST. VRAIN The following ORISE and Fort St. Vrain (FSV) final survey instrumentation and procedures will be reviewed and compared to ensure consistency between FSV final survey data and ORISE confirmatory survey data.

1.

Surface activity measurements using gas proportional detector A.

The specific material background radiation levels used to correct the gross counts will be determined for a number of surface types in unaffected areas at FSV. These areas will be considered to be representative of the areas included in the final survey. The surfaces will include various types of concrete, concrete block walls, brick surfaces, plasterboard (sheet rock) walls, tiled floors, steel I-beams, et cetera. The method used by FSV to determine background levels will be evaluated, and the results obtained by ORISE and FSV compared.

B.

Detector calibration will be evaluated, particularly the calibration source radionuclide, geometry of the source and source-to-detector spacing, window density thickness, and any other factors considered to have a measurable effect on the resultant efficiency.

C.

The minimum detectable activity equations will be compared and discussed.

Discussion topics will include background and sample count times.

D.

The interpretation of the raw survey data will be evaluated. Specific discussion items will include subtraction of the appropriate backgrounds, probe area corrections, and averaging areas for measurement data (e.g., the manner in which surface activity results betweeri one and three times the guideline will be treated). Consideration will be given to the 100 cm averaging area for the 2

maximum surface activity guideline and how the probe area correction of 125 2

cm may affect it.

E.

Following consideration of items A-D, side-by-side field measurements will be performed by ORISE and FSV, within affected areas, to compare actual surface activity levels. Both gross and net count rates will be compared, to determine the effect of background on the results.

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. Exposure rate measurements using PIC and NaI-based instrument A.

Background exposure rate levels will be determined for both indoor and i

outdoor areas within unaffected areas at FSV. These areas will be considered to be representative of the areas included in the final survey. Data will be reported in R/h. The method used by FSV to determine background levels will be evaluated, and the results obtained by ORISE and FSV compared.

B.

Instrument calibration will be evaluated, particularly the calibration source.

radionuclide, for representativeness to the expr.cted contaminants, and any other factors considered to have a measurable effect on the resultant efficiency.

C.

Procedures for exposure rate measurement averaging will be discussed (e.g.,

areas used for averaging).

D.

Following consideration ofitems A-C, side-by-side field measurements of exposure rate will be performed by ORISE and FSV, within indoor and outdoor affected areas, to determine actual exposure rates.

3.

Miscellaneous itemn A.

Smears for removable surface contamination will be discussed, particularly for the assessment of H-3 and Fe-55. Topics for discussion will include methodology for sample (smear) collection, e.g., moistened smears, and laboratory analysis procedures. Also, if moistened smears are used, in what manner will this affect analyses for the other anticipated contaminants?

B.

General discussion of instruments and procedures used for scanning, topics will include scanning sensitivity and background levels.

C.

Instrumentation and procedures for performing alpha surface activity measurements. Discuss situation where alpha and beta surface activity may be present and the use of alpha blockers (3.8 mg/cm Mylar).

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