ML20135A244
| ML20135A244 | |
| Person / Time | |
|---|---|
| Site: | 07000734 |
| Issue date: | 10/31/1996 |
| From: | Abelquist E, Bright T OAK RIDGE ASSOCIATED UNIVERSITIES |
| To: | |
| Shared Package | |
| ML20135A066 | List: |
| References | |
| NUDOCS 9612030133 | |
| Download: ML20135A244 (34) | |
Text
.
CONFIRMATORY SURVEY OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS J
SAN DIEGO, CALIFORNIA Prepared by E. W. Abelquist and T. L. Bright l
Environmental Survey and Site Assessment Program Environmental and Health Sciences Division Oak Ridge Institute for Science and Education Oak Ridge, Tennessee 37831-0117 Prepared for the Division of Fuel Cycle Safety and Safeguards U.S. Nuclear Regulatory Commission DRAFT REPORT OCTOBER 1996 l
9612030133 961106 l
PDR ADOCK 07000734 C
PDR t
This draft report has not been given full review and patent clearance, and the dissemirurdon of its information is only for official use. No release to the public shall be made without the approval i
of the Office of Information Services, Oak Ridge Institute for Science and Education.
This report is based on work performed under contract number DE-AC05-760R00033 with the U.S.
Department of Energy.
General Atonnes(655).Octoby 28,1996 hkasafseNrts general atogen_ atom 003
i ACKNOWLEDGMENTS t
i The authors would like to acknowledge the significant contributions of the following staff members I
t FIELD STAFF T.
L.
Bright i
LABORATORY STAFF i
R.
D.
Condra J.
S.
Cox M.
J.
Laudeman S.
T.
Shipley j
CLERICAL STAFF
. 7 D.
K.
Ash j
T.
S.
Fox K.
E.
Waters ILLUSTRATOR T.
L.
Bright 1
1 j
General Atonucs(655). October 28.1996 h 'essapaports' general ato' gen _ atom 003
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TABLE OF CONTENTS I
I r
i PAGE List of Figures.....
. ii I
List of Tables....
... iii i
Abbreviations and Acronyms iv l
l Introduction and Site History.....
-1 Site Description
......2 l
l Objective.
.2 Document Review.
.2 L
Procedures
..... 2-i Findings and Results l
.5 i
l Comparison of Results with Guidelines -
....6 l
l l
Summary
.7 References..
. 17 Appendices:
l Appendix A: Major Instrumentation r
Appendix B: Survcy and Analytical Procedures l
Appendix C: Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of Licenses for Byproduct, Source or Special Nuclear Material 6
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LIST OF FIGURES i
PAGE 1
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FIGURE 1:
General Atomics Facility Indicating Location of Building 2 8
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l FIGURE 2:
Building 2-Group 8B Laboratories.........
. 9 l
FIGURE 3:
Building 2, Rooms 506, 506A, 508, 508A-Measurement and l
Sampling Locations..
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FIGURE 4:
Building 2, Rooms 519/521-Measurement and Sampling Locations.
I1 I
FIGURE 5:
Building 2, Room 635-Measurement and Sampling Locations.
.. 12 l
FIGURE 6:
Building 2, Rooms'637/639-Measurement and Sampling Locations 13 l
l FIGURE 7:
Building 2, Mezzanine above Rooms 637/639-Measurement and Sampling Locations...
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i General Atonnes(655). October 28,1996 l
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1 LIST OF TABLES PAGE TABLE 1:
Summary of Surface Activity Levels 15 TABLE 2:
Exposure Rates
. 16 l
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I 5kk h 'essapseports' general atogen_ atom 003 General Atomics (655). October 28,1996
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ABBREVIATIONS AND ACRONYMS pR/h microroentgens per hour i
ASME American Society ofMechanical Engineers cm centimeter 2
t cm square centimeter cpm counts per minute i
DOE Department ofEnergy 2
dpm/100 cm disintegrations per minute per 100 square centimeters i
EML Environmental Measurements Laboratory EPA Environmental Protection Agency ESSAP Environmental Survey and Site Assessment Program GA General Atomics GM-Geiger-Mueller -
ha hectare j
hm kilometer
]
m meter 2
m square meter MDC Minimum Detectable Concentration NaI sodium iodide NIST.
National Institute of Standards and Technology NRC Nuclear Regulatory Commission j
ORISE Oak Ridge Institute for Science and Education l
pCi/g picoeuries per gram
)
ZnS zinc sulfide 1
)
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Ocaral Ataemes(655) October 28,1996 V
h Wsapveports' general ategen, atom 003
D CONFIRMATORY SURVEY OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA INTRODUCTION AND SITE HISTORY General Atomics (GA) has been in the process of decommissioning and obtaining the release for unrestricted use for a number of selected laboratories and associated offices in GA's Building 2 (also known as the Science Laboratories Building or "L" Building). Building 2, built in 1958, was used to conduct research and developmental activities. Activities involving radioactive material included 1
scanning electron microscopy and x'-ray diffraction on uranium and thorium samples, assembly of irradiation capsules containing enriched uranium, U-238, and thorium, and analysis of nuclear fuel elements. GA is licensed by the Nuclear Regulatory Commission (NRC) under license SNM-696, Docket 70-734. The facility is also licensed by the State of California.
Decommissioning efforts began in 1988 with a block oflaboratories known as " Group 1" To date, approximately eight groups oflabs have been decontaminated and released for unrestricted use. GA has recently performed a final status survey for another group of 11 laboratories in Building 2, identified as the " Group 8B" laboratories (GA 1996). The primary radionuclides used in these l
laboratories were uranium (including enriched uranium) and thorium. In the past, many cf these laboratories were decontaminated and then used for non-radiological purposes.
At the request of the NRC's Division ofFuel Cycle Saf ty and Safeguards, the Environmental Survey j
and Site Assessment Program (ESSAP) of the Oak Ridge Institute for Science and Education (ORISE) performed a confirmatory survey of the Group 8B labs. ESSAP performed a radiological 1
survey of the Group 6 laboratories of Building 2 in Febmary 1995 (ORISE 1995a).
j Ocneral Aurmes(655). October 28,1996 h Wasapwepons general aween_ atom 003
m._ _ - _ -.. _
8 SITE DESCRIPTION The GA facilities are located near the intersection ofInterstate 5 and Genesee Avenue in San Diego, California (Figure 1). Building 2 is divided into three laboratory sections: Laboratories A, B, and C.
1 Alllaboratories in Group 8B are located in laboratory section A (Figure 2). The eleven laboratories -
2 2
and one mezzanine consist of a total area of about 350 m. The labs range in size from 10 m to 60 1
j m, while the mezzanine for labs 635,637, and 639 has an area of 62 m. The labs are' designated:
2 2
5 506, 506A, 508, 508A, 515, 519/521 (combined lab), 523, 530/532, 635, 637/639, and the mezzanine for labs 635 and 637/639. The wall surfaces consist of standard constmetion materials such as j
cement block, plasterboard, drywall, and wood. Some of the walls are painted and the floors are l'
typically poured concrete. Tile wa.; removed from the floor in some labs by the licensee to facilitate i
the final status survey.
4 OBJECTIVES l
The objectives of the confirmatory survey are to provide independent contractor field data reviews and radiological data for use by the NRC in evaluating the adequacy and accuracy of the licensee's procedures and fmal status survey results.
DOCUMENT REVIEW ESSAP has reviewed the licensee's final status survey report (GA 1996). Procedures and methods used by the licensee were reviewed for adequacy and appropriateness. The data were reviewed for l
accuracy, completeness, and compliance with guidelines.
l PROCEDURES i
ESSAP personnel performed visual inspections and independent measurements and sampling of the i
Group 8B laboratories on September 16 and 17,1996. Survey activities were conducted in l
]
accordance with a site-specific survey plan (ORISE 1996), using procedures and instruments described in the ORISE/ESSAP Survey Procedures and Quality Assurance Manuals (uRISE 1995b l
2 General Ahwmes (655)
- Ociober 2s.1996 ss p*,po,i.
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t and c) and summarized in Appendices A and B. Rooms 506,506A,508,508A,519/521 (combined),
635,637/639, and the mezzanine were selected for confirmatory survey. This report summarizes the
[
procedures and results of the survey.
.1 j
REFERENCE GRID 5
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Measurement and sampling locations were referenced to prominent building features (e.g., doorways, j
. wall intersections, etc.) and recorded on representative area drawmgs.
SURFACE SCANS 1
Surface scans for alpha, beta, and gamma activity were performed at a frequency of approximately i
100 percent of the floors and 10 percent of the lower walls (up to 2 meters). Scans were performed using gas proponional and NaI scintillation detectors coupled to ratemeters or ratemeter-scaler with =
audible indicators.. Locations of elevated direct radiation detected by scans were marked for further l
investigation.
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h SURFACE ACTIVITY MEASUREMENTS
[
?
Background measurements of surface activity on poured concrete, sheet rock and concrete blocks, were performed at building locations that did not have a history of radioactive materials use.
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Direct measurements for total alpha and total beta activity were performed at a total of 66 floor and lower wall locations in the surveyed lab areas. In addition, two five-point measurements were 2
performed to. determine the 1 m grid block average beta surface activity in room 508. Direct measurements were performed using gas proportional detectors coupled to ratemeter-scalers. A smear sample for the determination of removable gross alpha and gross beta activity was collected at each direct measurement location.
Figures 3 through 7 show measurement and sampling i
j locations.
1 i
General Aiomics(653).Ociohe,28,1996 3
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l Additional direct measurements were performed at locations of elevated direct radiation identified i
j by surface scans.
1-
}
EXPOSURE RATE MEASUREMENTS i
Background exposure rate levels were determined for the building interior at 5 locations of similar construction but without a history of radioactive materials use. Exposure rates were performed at a total of 16 locations in the surveyed labs and the mezzanine area. Exposure rate measurements j
were performed at 1 m. above the floor surface using a microrem meter. Figures 3 through 7 show :
measurement locations.
2 i.
I MISCELLANEOUS SAMPLING l
J J
A paint sample was collected from a 100 cm area located off the lower portion of the south wall of.
2 Room 508. Sample location is indicated on Figure 3.
i SAMPLE ANALYSIS AND DATA INTERPRETATION Samples and survey data were returned to ORISE's ESSAF laboratory in Oak Ridge, Tennessee for analysis and interpretation. ' The paint sample was analyzed by gamma and alpha spectrometry and '
I 2
results reponed in dpm/100 cm for the paint sample. Direct measurements for surface activity were converted to units ofdisintegrations per minute per 100 square centimeters (dpm/100 cm ). Smears 2
were analyzed for gross ' lpha and gross beta activity using a low background gas proportional a
2 counter, and the results converted to units of dpm/100 cm. Exposure rate measurements were reported in units of pR/h. The radionuclides ofinterest are uranium and thortim; however, spectra j
were reviewed for other identifiable photopeaks Sample analyses were performed in accordance with the ORISE/ESSAP Laboratory Procedures Manual (ORISE 1995d). Additional information
- concerning major instrumentation is provided in Appendices A and B. Results were compared to the licensee's documentation and NRC guidelines established for release for unrestricted use, which are provided in Appendix C.
Ocneral Atornics (655). October 28.1996 4
toessapveports'generat ato' gen. atom 003
FINDILGS AND RESULTS DOCUMENT REVIEW ESSAP reviewed the licensee's radiological survey data and comments were provided verbally to the NRC and licensee. The licensee provided responses to those comments. In ESSAP's opinion, the licensee's documentation provided an adequate description of the radiological condition of the facility relative to the NRC guidelines for release for unrestricted use.
Surface Scans Surface scans identified one area of elevated beta-gamma activity in room 508 (Figure 3).
Surface Activity Levels i
Surface activity levels are summariz d in Table 1. The results of single-point measurements ranged -
j 2
2 from less than 52 dpm/100 cm for alpha activity and less than 310 to' 1700 dpm/100 cm for beta 2
activity. Grid block average activity in room 508 was less than 52 dpm/100 cm and 400 to 1,000 2
- dpm/100 cm for alpha and beta, respectively. Removable activity levels were less than 14 dpm/100 2
2 cm for gross alpha and less than 16 dpm/100 cm for gross beta.
Exposure Rates Exposure rate measurement data is provided in Table 2. Background interior exposure rates ranged from 13 to 14 pR/h and averaged 14 pR/h. Exposure rates for the surveyed labs and the mezzanine area ranged from 11 to 17 pR/h.
Radionuclide Concentration in Paint The radionuclide concentration in paint was qualitatively assessed to be enriched uranium.
General Alanucs(655). October 28. IM 5
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COMPARISON OF RESULTS WITH GUIDELINES The primary contaminants of concern for this site are natural thorium and enriched uranium. The applicable NRC guidelines for residual thorium and enriched uranium surface activity levels are (NRC -
1987):
Natural thorium 2
2 1,000 dpm/100 cm, averaged over a 1 m area 2
2 3,000 dpm/100 cm, maximum in a 100 cm area 2
200 dpm/100 cm, removable activity Enriched uranium 2
2 5,000 dpm a/100 cm, total, averaged over a 1 m area 2
2 15,000 dpm a/100 cm, total, maximum in a 100 cm area 2
1,000 dpm a/100 cm, removable activity-Direct measurements performed on the south wall oflaboratory 508 exceeded the average guideline -
for natural thorium-average' surface activity measured 1,000 dpm/100 cm (surface activity slightly 2
exceeded guideline prior to rounding to two significant figures). After further investigation by the licensee, it was discovered that calibration gamma sources were being' stored in the adjacent active laboratory - Direct measurements taken by the licensee before and after the removal of the sources indicate that the sources may be the cause of the elevated measurements. However, a paint sample collected by ESSAP from this' area identified that the contamination was due to enriched uranium.
The alpha-to-beta ratio for low enriched uranium may be approximated by a 3:1 ratio; therefore, the 2
corresponding average beta activity guideline may be adjusted to 1,700 dpm/100 cm,
The guideline for exposure rates measured at I m above the surface is 5 pR/h above background (NRC 1991), All exposure rate measurements were within these guidelines.
' Ocneral Atormes(655). October 28,'lM '
b hWyeponstgeneral sto' gen _stom 003
SUMMARY
The Environmental Survey and Site Assessment Program of the Oak Ridge Institute for Science and Education conducted confirmatory activities for the Group 8B laboratories at the General Atomics j
Building 2 in San Diego, California. Confirmatory activities included document reviews and on September 16 and 17,1996, ESSAP personnel visited the site and performed independent surface f
scans, surface activity measurements, miscellaneons sampling and exposure rate measurements.
The results of the independent confirmatory measurements and sampling supported the conclusions of the licensee's survey, relative to satisfying the guidelines established for this project.
7 h 'essapweports' general alo' gen _stant003 General Atonucs (655)- October 28.1996
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4 EXPOSURE RATE FIGURE 3: Building 2, Rooms 506, 506A, 508, 508A - Measurement and Sampling Locations 10 General Atomics (655)- October 28, im an,,,,ps,,po,,,,,,ncr,i.
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4 EXPOSURE RATE o METERS FIGURE 4: Building 2, Rooms 519/521 - Measurement and Sampling Locations i
11 h 'essap'seports' general.ato'. gen _anwn 003 General Atomics (655)-October 28,1996
655-005(1)
SERVICE CORE 10 9
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NM br
$ SINGLE-POINT FLOOR A SINGLE-POINT LOWER WALL 0
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Building 2, Rooms 635 - Measurement and Sampling Locations l
General Atomics (655)- Octoter 28,1996 2
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HALLWAY MEASUREMENT /SAMPUNG LOCATIONS at RM g
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@E EXPOSURE RATE FIGURE 6:
Building 2, Rooms 637/639 - Measurement and Sampling Locations 13 General Atomics (655)-October 28,1996 h \\essap' reports'generaLatoigen, atom.003 l
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655-009 (1)
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=-
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MEXPOSURERATE FIGURE 7:
Building 2, Mezzanine above Rooms 637/639 - Measurement and Sampling Locations 4
h%ssywd.gened awgen_ atom 00 General Atomics (655) Octoter 28.1996
I 1
TABLE 1
SUMMARY
OF SURFACE ACTIVITY LEVELS OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA ange of RemovaNe Number Range of Total Activity Activity i
2 Location" Measurement (dpm/100 cm )
2 l
(dpm/100 cm )
Location Alpha Beta Alpha Beta 13 Coor
<52
<310-830
<14
<16 Labs 506/506A/508/508A 7 Lower wall
<29
<260-1,700
<l4
<16 6 0oor
<52
<310
<14
<16 Labs 519/521 4 Lower wall
<29
<290
<14
<16 7 0oor
<52
<310
<14
<16 i
Lab 635 f'
2 Lower wall
<29
<290
<l4
<l6 12 floor
<52
<310
<l4
<l6 Lab 637/639 4 Lower wall
<29
<290
<l4
<16 100oor
<29
<260
<14
<16 Mezzanine 635/637/639 1 Lower wall
<29
<290
<14
<16
'See Figures 3 through 7.
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General Atomus (655). October 28, lu 15 a w.gw.eomi.w co_.t w3
TABLE 2 EXPOSURE RATES
]
OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA Location' Exposure Rate Measurement (pR/hr)
Labs 506 #1 13 Lab 506A #2 16 Lab 508 #3 15 Labs 519/521 #5 15 t
Labs 519/521 #6 17 Labs 519/521 #7 14 Lab 635 #8 13 Lab 635 #9 12 Lab 635 #10 11 Labs 637/639 #11 14 Labs 637/639 #12 14 i
Labs 637/639 #13 14 Mezzanine #14 -
12 Mezzanine #15 11 Mezzanine #16 13 "See Figures 3 through 7.
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General Atonucs (655). ociober 23, tm I6 Nyrepatswil esm_ atom m3 L
REFERENCES General Atomics (GA). Decontamination of Selected General Atomics' Science Laboratories for Release to Unrestricted Use (Group 8B). August 23,1996.
Oak Ridge Institute for Science and Education. Radiological Survey for the Group 6 Laboratories, Building 2, General Atomics, San Diego, California. Oak Ridge,'TN; May 1995a.
Oak Ridge Institute ' for Science and Education. Survey Procedures Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 9. Oak Ridge, Tennessee; April 30,1995b.
- Oak Ridge Institute. for Science and Education.
Quality. Assurance Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 7. Oak Ridge, Tennessee; January 31,1995c.
Oak Ridge Institute for Science' and Education.
Laboratory Procedures Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 9. Oak Ridge, Tennessee; January 31,1995d.
Oak Ridge Institute for Science and Education (ORISE). Confirmatory Survey Plan for Building 2, Group 8B Laboratories, General Atomics, San Diego, California. Oak Ridge, Tennessee; September 1996.
U.S. Nuclear Regulatory Commission (NRC). Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of License for Byproduct, Source, or Special Nuclear Material. Washington, DC: NRC; August 1987.
U.S. Nuclear Regulatory Commission. Policy and Guideline Directive FC91-2, Standard Review Plan: Evaluating Decommissioning Plans for Licenses Under 10 CFR Parts 30, 40, and 70.
Washington, DC: NRC; August 1991.
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7 h %@ general udgen_aue MG General Atomics (635). October 28. IM
i APPENDIX A MAJOR INSTRUMENTATION General Atomics (655)-October 2N. I9%
h 'essapveports' general ato'Sen_ atom.003
APPENDIX A MAJOR INSTRUMENTATION The display of a specific product is not to be construed as an endorsement of the product or its manufacturer by the authors or their employer.
DIRECT RADIATION MEASUREMENT Instruments Eberline Pulse Ratemeter Model 12 1
(Eberline, Santa Fe, NM)
Ludlum Floor Monitor i
Model 239-1 (Ludlum Measurements, Inc.,
)
Sweetwater, TX) i Ludlum Ratemeter-Scaler i
Model 2221 (Ludlum Measurements, Inc.,
Sweetwater, TX)
Detectors Eberline GM Detector Model HP-260 2
Effective Area,20 cm (Eberline, Santa Fe, NM) i Ludlum Gas Proponional Detector Model 43-37 2
Effective Area,550 cm (Ludlum Measurements, Inc., Sweetwater, TX)
Ludlum Gas Proportional Detector Model 43-68 2
Effective Area,126 cm (Ludlum Measurements, Inc., Sweetwater, TX)
A-1 e m,wxa mi.e.en..i. w3 General Aucucs (655). October 28. Im
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Bicron Micro-RemMeter i
Tissue Equivalent Survey Meter i
(Bicron Corporation, Newberry, OH) ~
l Victoreen Nal Scintillation Detector i
Model 489-55 3.2 cm x 3.8 cm Crystal (Victoreen, Cleveland, OH)
LABORATORY ANALYTICAL INSTRUMENTATION
. Low Background Gas Proportiotia! Counter Model LB-5100-W (Oxford, Oak Ridge, TN) l l
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I-i I-r 4
1 A-2 n se ps, pon.
er.i.io o_.io, 003 General Atormc. (655). October 28,1996
APPENDIX B 1
SURVEY AND ANALYTICAL PROCEDURES j
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CWral Atorna(655). October 28.1996 h 'Meeportsgeneral ato gen _atorn tr>3
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APPENDIX B 1
SURVEY AND ANALYTICAL PROCEDURES i
SURVEY PROCEDURES Surface Scans 1
4 i
Surface scans were performed by passing the detectors slowly over the surface; the distance between the detector and the surface was maintained at a minimum-nominally about I cm. A large surface i
area, gas proportional floor monitor was used to scan the floors ofthe surveyed areas. Other surfaces 2
2 were scanned using small area (20 cm or 126 cm ) hand-held detectors. Identification of elevated I
levels was based on increases in the audible signal from the recording and/or indicating instmment, c
Combinations of detectors and instruments used for the scans were:
Alpha gas proportional detector with ratemeter-scaler ZnS scintillation detector with ratemeter-scaler gas proportional detector with ratemeter-scaler Beta GM detector with ratemeter-scaler Gamma Nal scintillation detector with ratemeter Surface Activity Measurements Measurements of total beta activity levels were primarily performed using gas proportional detectors with ratemeter-scalers.
Count rates (cpm), which were int _egrated over 1 minute in a static position, were converted to j
activity levels (dpm/100 cm') by dividing the net rate by the 4 n efliciency and correcting for the active area of the detector. Because different building materials (poured concrete, concrete block, metal, wood, etc.) can have very different background levels, average background counts were B-1
%gnoi 5.mi
_.u-w3 comi umm. assn m a. iu
determined for each material encountered in the surveyed area at a location of similar construction and having no known radiological history. The beta activity background count rates for the gas proportional detectors averaged 618 cpm for poured concrete,430 cpm for sheet rock, and 524 cpm for cinder block. Alpha background count rates for the gas proportional detectors averaged 5 cpm for poured concrete, I cpm for sheet rock and I cpm for cinder block. Net count rates were determined by subtracting the appropriate material background from the gross count rate for each measurement location. The beta emeiency factor was 0.29 for the gas proponional detector calibrated to TI-204. The beta minimum detectable concentrations (MDC) for the gas proportional detectors varied by material and ranged from 260 to 310 dpm/100 cm. The alpha emeiency factor 2
was 0.2 for the gas proportional detectors calibrated to Th-230 and MDCs ranged from 30 to 50 2
2 dpm/100 cm. The physical window area for the gas proportional detectors is 126 cm,
Removable Activity Measuremenu Removable activity levels were determined using numbered filter paper disks,47 mm in diameter.
Moderate pressure was applied to the smear and approximately 100 cm of the surface was wiped.
2 Smears were placed in labeled envelopes with the location and other pertinent information recorded.
Exposure Rate Measuremnth keasurements of gamma exposure rates were performed using a microrem meter. The instmment was held at one meter above the surface. The measurement was read directly in pR/h.
ANALYTICAL PROCEDURES Gross Alpha / Beta Smears were counted on a low-background gas proportional system for gross alpha, and gross beta activity.
B-2 6 ww.enmi u,en_.-m General Atomics (655). October 28.1996
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1 i
UNCERTAINTIES AND DETECTION LIMITS 1
The uncenainties associated with the analytical data presented in the tables of this report represent i
the 95% confidence level for that data. These uncertainties were calculated based on both the gross sample count levels and the associated background count levels. Additional uncertainties, associated with sampling and measurement procedures, have not been propagated into the data presented in this report.
Detection limits, referred to as minimum detectable concentration (MDC), were based on 2.71 plus l-4.65 times the standard deviation of the background count (2.71 + 4.65/BKG]. When the activity l
l was determined to be less than the MDC of the measurement procedure, the result was reported as f
less than MDC. Because of variations in background levels, measurement efficiencies, and contributions from other radionuclides in samples, the detection limits differ from sample to sample l'
and instrument to instrument.
i l'
CALIBRATION AND QUALITY ASSURANCE Calibration of all field and laboratory instrumentation was based on standards / sources, traceable to NIST, when such standard / sources were available. In cases where they were not available, standards of an industry recognized organization were used.
Analytical and field survey activities were conducted in accordance with procedures from the following documents of the Environmental Survey and Site Assessment Program:
Survey Procedures Manual, Revision 9 (April 1995)
Laboratory Procedures Manual, Revision 9 (January 1995)
Quality Assurance Manual, Revision 7 (January 1995)
\\
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B-3 a wy,.wyn i.nen..n.om Genaal Atonucs(655). October 28 im
i a
The procedures contained in these manuals were developed to meet the requirements of DOE Order l
5700.6C and ASME NQA-1 for Quality Assurance and contain measures to assess processes during their performance.
1
- Quality control procedures include:
I 1
Daily instrument background and check-source measurements to confirm that equipment operation is within acceptable statistical fluctuations.
Participation in EPA and EML laboratory Quality Assurance Programs.
l Training and certification of allindividuals performing procedures.
Periodic internal and external audits.
1 l
i I
b-4 h Weg end amgen nuamM3 General Atomms (eM). October 28. Im g
1 i
i l
l l
l APPENDIX C t
GUIDELINES FOR DECONTAMINATION OF FACILITIES AND EQUIPMENT PRIOR TO RELEASE FOR UNRESTRICTED USE OR TERMINATION OF LICENSES FOR BYPRODUCT, SOURCE OR SPECIAL NUCLEAR MATERIAL U. S. Nuclear Regulatory Commission Division of Fuel Cycle & Material Safety Washington, D.C. 20555 August 1987 l
t l
l General Atonucs(655). October 25,19%
h enapweports general aidgen_ atom 003 l
l The instructions in this guide, in conjunction with Table 1, specify the radionuclides and radiation exposure rate limits which should be used in decontamination and survey of surfaces or premises and equipment prior to abandonment or release for unrestricted use. The limits in Table 1 do not apply to premises, equipment, or scrap containing induced radioactivity for which the radiological considerations nertinent to their use may be different. The release of such facilities or items from regulatory control is considered on a case-by-case basis.
1.
The licensee shall make a reasonable effort to eliminate residual contamination.
2.
Radioactivity on equipment or surfaces shall not be covered by paint, plating, or other covering material unless contamination levels, as determined by a survey and documented, are below the limits specified in Table 1 prior to the application of the covering. A reasonable effort must be made to minimize the contamination prior to use of any covenng.
3.
The radioactivity on the interior surfaces of pipes, drain lines, or ductwork shall be determined by making measurements at all traps, and other appropriate access points, provided that contamination at these locations is likely to be representative of contamination on the interior of the pipes, drain lines, or ductwork. Surfaces or premises, equipment, or scrap which are likely to be contaminated, but are of such size, construction, or location as to make the surface inaccessible for purposes of measurement, shall be presumed to be contaminated in excess of the limits.
4.
Upon request, the Commission may authorize a licensee to relinquish possession or control of premises, equipment, or scrap having surfaces contaminated with materials in excess of the limits specified. This may include, but would not be limited to special circumstances such as razing of buildings, transfer from premises to another organization continuing work with radioactive materials, or conversion of facilities to a long-term storage or standby status. Such requests must:
i b*!
h mpnWenal ate >Matom (G General Atormes(655)-October 3, im
i
'l Provide detailed, specific information describing the premises, equipment or scrap, a.
radioactive contaminants, and the nature, extent, and degree of residual surface contamination.
j b.
Provide a detailed health and safety analysis which reflects that tiie residual amounts of materials on surface areas, together with other considerations such as prospective use of the premises, equipment, or scrap, are unlikely to result in an unreasonable risk to the health and safety of the public.
5.
Prior to release of premises for unrestricted use, the licensee shall make a comprehensive j
1 radiation survey which establishes that contamination is within the limits specified in Table 1.
i A copy of the survey report shall be filed with the Division of Fuel Cycle, Medical, Academic, and Commercial Use Safety, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, and also the Administrator of the NRC Regional Office havingjurisdiction. The report should be filed at least 30 days prior to the planned date of abandonment. The sun'ey report shall:
i a.
Identify the premises.
b.
Show that reasonable effort has been made to eliminate residual contamination.
c.
Describe the scope of the survey and general procedures followed.
d.
State the findings of the survey in units specified in the instruction.
Following review of the report, the NRC will consider visiting the facilities to confirm the survey.
C*2 hp%enal aWgen atom MB General Atunuca (6$5). October ON, iW
TABLE 1 ACCEPTABLE SURFACE CONTAMINATION LEVELS a
E E
Nuclides' Average
- f Maximum df Removable *f 6
6 6
associated decay products 5,000 dpm a/100 cm 15,000 dpm d100 cm 1,000 dpm a/100 cm 2
2 2
If E
Transuranics, Ra-226, Ra-228, 3
2 2
Ac-227,1-125,1-129 100 dpm/100 cm 300 dpm/100 cm 20 dpm/100 cm Th-nat, Th-232, Sr-90, Ra-223 2
2 2
Ra-224 U-232, I-126,1-131, I-133 1,000 dpm/100 cm 3,000 dpm/100 cm 200 dpm/100 cm Beta-gamma emitters (nuclides with decay modes other than alpha emission
{
or spontaneous fission) except Sr-90 2
2 2
and others noted above.
5,000 dpm py/100 cm 15,000 dpm py/100 cm 1,000 dpm py/100 cm
~
'Where surface contamination by both alpha-and beta-gamma-emitting nuclides exists, the limits established for alpha-and beta-gamma-emitting nuclides should apply independently.
As used in this table, dpm (disintegrations per minute) means the rate of emission by radioactive material cs determined by correcting 6
the counts per minute observed by an appropriate detector for background, efficiency, and geometric factors associated with the instrumentation.
' Measurements of average contaminant should not be averaged over more than 1 square meter. For objects ofless surface area, the E
average should be derived for each such object.
}
dThe maximum contamination level applies to an area of not more than 100 cm,
2
}
'The amount of removable radioactive material per 100 cm of surface area should be determined by wiping that area with dry filter 2
j or soft absorbent paper, applying moderate pressure, and assessing the amount of radioactive material on the wipe with an appropriate
[
instrument of known efficiency. When removable contamination on objects ofless surface area is determined, the pertinent levels j
should be reduced proportionally and the entire surface should be wiped.
j
'The average and maximum radiation levels associated with surface contamination resulting from beta-gamma emitters should not g
exceed 0.2 mrad /h at I cm and 1.0 mrad /h at I cm, respectively, measumd through not more than 7 milligrams per square centimeter of total absorber.
l e
,p i
CONFIRMATOR'Y SURVEY OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA i
Prepared by l
E. W. Abelquist and T. L. Bright Environmental Survey and Site Assessment Program Environmental and Health Sciences Division Oak Ridge Institute for Science and Education Oak Ridge, Tennessee 37831-0117 Prepared for the Division of Fuel Cycle Safety and Safeguards U.S. Nuclear Regulatory Commission DRAFT REPORT OCTOBER 1996 This draft report has not been given full review and patent clearance, and the dissemination ofits information is only for official use. No release to the public shall be made without the approval of the Office ofInformation Services, Oak Ridge Institute for Science and Education.
This report is based on work performed under contract number DE-AC05-760R00033 with the U.S.
Department of Energy.
General Atomics (655). October 28.1996 h kssapVepons\\ general atoigen_stom 003
'I
',a ACKNOWLEDGMENTS The authors would like to acknowledge the significant contributions of the following staff
-members:
FIELD STAFF T.
L.
Bright LABORATORY STAFF R.
D.
Condra J.
S.
Cox M.
J.
Laudeman S.
T.
Shipley CLERICAL STAFF D.
K.
Ash T.
S.
Fox K.
E.
Waters ILLUSTRATOR T.
L.
Bright General Atorrucs (655). October 28,1996 h%ssapvepatsgaral atogen_m M3
TABLE OF CONTENTS PAGE List of Figures
. ii List of Tables.
iii Abbreviations and Acronyms.
iv Introduction and Site History.
1 i
i Site Description
.2 Objective
.2 Document Review
.2 Procedures
.2 i
Findings and Results
.5 Comparison of Results with Guidelines
.6 Summary
.7 References.
. 17 Appendices:
Appendix A: Major Instrumentation Appendix B: Smvey and Analytical Procedures Appendix C: Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of Licenses for Byproduct, Source or SpecialNuclear Material i
l Messap\\reportsigeneral atoigen_stom003 General Atonues(655) October 28,1996
1 c
+
4 i
LIST OF FIGURES PAGE l
FIGURE 1i General Atomics Facility Indicating Location ofBuilding 2 8'
l
.i -
FIGURE 2:
Building 2-Group 8B Laboratories...
.9 1
FIGURE 3:
Building 2, Rooms 506, 506A, 508, 508A-Measurement and Sampling Locations..
10 FIGURE 4:
Building 2, Rooms 519/521-Measurement and Sampling Locations,
. I1
.)
I
.. Building 2, Room 635-Measurement and Sampling Locations 12 FIGURE 5:
i
)
{
FIGURE 6:
Building 2, Rooms 637/639-Measurement and Sampling Locations.
13 l
i FIGURE 7:
Building 2, Mezzanine above Rooms 637/639-Measurement and Sampling Locations 14 5
i j
l 4
4 4
4 j
l I
i i
i General Atonucs (655). October 23.1996 k
h.kssapVeportageneral atogen_stom 003
1 LIST OF TABLES 1
PAGE
- TABLE 1:
Summary of Surface Activity Levels...
.......................,15' TABLE 2:
Exposure Rates............
. 16 3
l r
s 9'
s Ir 1
I
!' f' i
,. I f
I 4
o auomic.g55).oa n,im iii h wpw,~.s.-.- 2.=t<4ea_ata=oo3
c ABBREVIATIONS AND ACRONYMS-pR/h microroentgens per hour ASME American Society ofMechanical Engineers.
cm
. centimeter 2
cm square centimeter cpm
' counts per minute DOE Department ofEnergy 2
dpm/100 cm disintegrations per minute per 100 square centimeters EML.
Environmental Measurements Laboratory EPA EnvironmentalProtection Agency ESSAP Environmental Survey and Site Assessment Program GA General Atomics GM Geiger-Mueller ha hectare km kilometer m
meter 2
m square meter MDC Minimum Detectable Concentration NaI sodium iodide NIST National Institute of Standards and Technology NRC Nuclear Regulatory Commission ORISE Oak Ridge Institute for Science and Education pCi/g picocuries per gram ZnS zine sulfide General Atomics (655) October 28,1996 1y hwsepVeponsgeneral sto%en_atont003
CONFIRMATORY SURVEY OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA INTRODUCTION AND SITE HISTORY General Atomics (GA) has been in the process of decommissioning and obtaining the release for unrestricted use for a number of selected laboratories and associated offices in GA's Building 2 (also known as the Science Laboratories Building or "L" Building). Building 2, built in 1958, was used to conduct research and developmental activities. Activities involving radioactive material included scanning electron microscopy and x-ray diffraction on uranium and thorium samples, assembly of irradiation capsules containirig enriched uranium, U-238, and thorium, and analysis of nuclear fuel elements. GA is licensed by the Nuclear Regulatory Commission (NRC) under license SNM-696, Docket 70-734. The facility is also licensed by the State of California.
Decommissioning efforts began in 1988 with a block oflaboratories known as " Group 1" To date, approximately eight groups oflabs have been decontaminated and released for unrestricted use. GA has recently performed a final status survey for another group of 11 laboratories in Building 2, identified as the " Group 8B" laboratories (GA 1996). The primary radionuclides used in these laboratories were uranium (including enriched uranium) and thorium. In the past, many of these laboratories were decontaminated and then used for non-radiological purposes.
At the request of the NRC's Division ofFuel Cycle Safety and Safeguards, the Environmental Survey and Site Assessment Program (ESSAP) of the Oak Ridge Institute for Science and Education (ORISE) performed a confirmatory survey of the Group 8B labs. ESSAP performed a radiological i
survey of the Group 6 laboratories of Building 2 in February 1995 (ORISE 1995a).
l l
ommi u-,c. gss). ocwb-::. im W=pveres==t amwen== m3
s SITE DESCRIPTION The GA facilities are located near the intersection ofInterstate 5 and Genesee Avenue in San Diego, California (Figure 1). Building 2 is divided into three laboratory sections: Laboratories A, B, and C.
Alllaboratories in Group 8B are located in laboratmy section A (Figure 2). The eleven laboratories 2
2 and one mezzanine consist of a total area of about 350 m. The labs range in size from 10 m to 60 2
2 m, while the mezzanine for labs 635,637, and 639 has an area of 62 m. The labs are designated:
506, 506A, 508, 508A, 515, 519/521 (combined lab), 523, 530/532, 635, 637/639, and the mezzanine for labs 635 and 637/639. The wall surfaces consist of standard constmetion materials such as cement block, plasterboard, drywall, and wood. Some of the walls are painted and the floors are typically poured concrete. Tile was removed from the floor in some labs by the licensee to facilitate the final status survey.
OBJECTIVES The objectives of the confirmatory survey are to provide independent contractor field data reviews and radiological data for use by the NRC in evaluating the adequacy and accuracy of the licensee's l
procedures and final status survey results.
DOCUMENT REVIEW l
ESSAP has reviewed the licensee's final status survey report (GA 1996). Procedures and methods used by the licensee were reviewed for adequacy and appropriateness. The data were reviewed for accuracy, completeness, and compliance with guidelines.
i PROCEDURES ESSAP personnel performed visual inspections and independent measurements and sampling of the Group 8B laboratories on September li and 17, 1996. Survey activities were conducted in accordance with a site-specific survey plan (ORISE 1996), using procedures and instruments described in the ORISE/ESSAP Survey Procedures and Quality Assurance Manuals (ORISE 1995b General AlJrmes(655).Octota 28,1996 h \\essapVeports'Sencral atogen, atom 003
and c) and summarized in Appendices A and B. Rooms 506,506A,508,508A,519/521 (combined),
635,637/639, and the mezzanine were selected for confirmatory survey. This report summarizes the procedures and results of the survey.
REFERENCE GRID Measurement and sampling locations were referenced to prominent building features (e.g., doorways, wallintersections, etc.) and recorded on representative area drawings.
SURFACE SCANS Surface scans for alpha, beta, and gamma activity were performed at a frequency of approximately 100 percent of the floors and 10 percent of the lower walls (up to 2 meters). Scans were performed using gas proportional and NaI scintillation detectors coupled to ratemeters or ratemeter-scaler with -
audible indicators. Locations of elevated direct radiation detected by scans were marked for further investigation.
SURFACE ACTIVITY MEASUREMENTS Background measurements of surface activity on poured concrete, sheet rock and concrete blocks, were performed at building locations that did not have a history of radioactive materials use.
Direct measurements for total alpha and total beta activity were performed at a total of 66 floor and lower wall locations in the surveyed lab areas. In addition, two five-point measurements were 2
performed to determine the 1 m grid block average beta surface activity in room 508. Direct measurements were performed using gas proportional detectors coupled to ratemeter-scalers. A smear sample for the determination of removable gross alpha and gross beta activity was collected at each c" :t measurement location.
Figures 3 through 7 show measurement and sampling locations.
I l
3
%vepon.w o. tow _.tomm3 General Atomics (655). October 28.1.
a Additional direct measurements were performed at locations of elevated direct radiation identified by surface scans.
l EXPOSURE RATE MEASUREMENTS Background exposure rate levels were determined for the building interior at 5 locations of similar construction but without a history ofradioactive materials use. Exposure rates were performed at a total of 16 locations in the surveyed labs and the mezzanine area. Exposure rate measurements were performed at 1 m above the floor surface using a microrem meter. Figures 3 through 7 show measurement locations.
l MISCELLANEOUS SAMPLING A paint sample was collected from a 100 cm area located off the lower portion of the south wall of 2
Room 508. Sample location is indicated on Figure 3.
SAMPLE ANALYSIS AND DATA INTERPRETATION Samples and survey data were returned to ORISE's ESS AP laboratory in Oak Ridge, Tennessee for analysis and interpretation. The paint sample was analyzed by gamma and alpha spectrometry and 2
results reported in dpm/100 cm for the paint sample. Direct measurements for surface activity were 2
converted to units ofdisintegrations per minute per 100 square centimeters (dpm/100 cm ). Smears were analyzed for gross alpha and gross beta activity using a low background gas proportional 2
counter, and the results converted to units of dpm/100 cm. Exposure rate measurements were reported in units of pR/h. The radionuclides ofinterest are uranium and thorium; however, spectra were reviewed for other identifiable photopeaks. Sample analyses were performed in accordance with the ORISE/ESSAP Laboratory Procedures Manual (ORISE 1995d). Additional information concerning majorinstrumentation is provided in Appendices A and B. Results were compared to the licensee's documentation and NRC guidelines established for release for unrestricted use, which are provided in Appendix C.
4 hkssapveportsgeneral atogen_stom 003 General Atonnes (655). October 25.1996
FINDINGS AND RESULTS DOCUMENT REVIEW ESSAP reviewed the licensee's radiological survey data and comments were provided verbally to the NRC and licensee. The licensee provided responses to those comments. In ESSAP's opinion, the licensee's documentation provided an adequate description of the radiological condition of the facility relative to the NRC guidelines for release for unrestricted use.
Surface Scans Surface scans identified one area of elevated beta-gamma activity in room 508 (Figure 3).
Surface Activity Levels Surface activity levels are summarized in Table 1. The results of single-point measurements ranged 2
2 from less than 52 dpm/100 cm for alpha activity and less than 310 to 1700 dpm/100 cm for beta 2
activity. Grid block average activity in room 508 was less than 52 dpm/100 cm and 400 to 1,000 2
dpm/100 cm for alpha and beta, respectively. Removable activity levels were less than 14 dpm/100 2
2 cm for gross alpha and less than 16 dpm/100 cm for gross beta.
Exposure Rates Exposure rate measurement data is provided in Table 2. Background interior exposure rates ranged from 13 to 14 pR/h and averaged 14 pR/h. Exposure rates for the surveyed labs and the mezzanine area ranged from 1I to 17 pR/h.
Radionuclide Concentration in Paint The radionuclide concentration in paint was qualitatively assessed to be enriched uranium.
i 5
av ps,. pori.w.,.i.io o_.i o03 s
General Atomics (65$). October 21,lM
~.
.. ~.
- COMPARISON OF RESULTS WITH GUIDELINES The primary contaminants of concern for this site are natural thorium and enriched uranium. The applicable NRC guidelines for residual thorium and enriched uranium surface activity levels are (NRC 1987):
Natural thorium 2
2 1,000 dpm/100 cm, averaged over a 1 m area 2
2 3,000 dpm/100 cm, maximum in a 100 cm area 2
200 dpm/100 cm, removable activity i
Enriched uranium 2
2 5,000 dpm a/100 cm, total, averaged over a 1 m area 2
2 15,000 dpm a/100 cm, total, maximum in a 100 cm area 2
1,000 dpm a/100 cm, removable activity
. Direct measurements performed on the south wall oflaboratory 508 exceeded the average guideline 2
for natural thorium-average surface activity measured 1,000 dpm/100 cm (surface activity slightly exceeded guideline prior to rounding to two significant figures). After further investigation by the licensee, it was discovered that calibration gamma sources were being stored in the adjacent active laboratory. Direct measurements taken by the licensee before and after the removal of the sources L
' indicate that the sources may be the cause of the elevated measurements. However, a paint sample i
collected by ESSAP from this area identified that the contamination was due to enriched uranium.
The alpha-to-beta ratio for low enriched uranium may be approximated by a 3:1 ratio; therefore, the 2
- corresponding average beta activity guideline may be adjusted to 1,700 dpm/100 cm,
The guideline for exposure rates measured at 1 m above the surface is 5 pR/h above background (NRC 1991). All exposure rate measurements were within these guidelines.
4 Ocneral Atormes (6$5). October 28.1996 b
h:\\essap\\ reports \\ general.ato\\ gen _stom 003 l
SUMMARY
The Environmental Survey and Site Assessment Progiam of the Oak Ridge Institute for Science and Education conducted confirmatory activities for the Group 8B laboratories at the General Atomics Building 2 in San Diego, California. Confirmatory activities included document reviews and on i
September 16 and 17,1996, ESSAP personnel visited the site and performed independent surface '
l scans, surface activity measurements, miscellaneous sampling and exposure rate measurements.
l The results of the independent confirmatory measurements a.,d sampling supported the conclusions i
of the licensee's survey, relative to satisfying the guidelines established for this project.
l i
1 l
7 hkssap\\ reports \\ general sto\\ gen _stant003 l
General Atomics (655)-October 28,im l
' 655-011 (x)
\\\\
o b
SORRENTO VALLEY, 0+
SECTION A
'\\
Ogdb
'94
'NQUNHILL s
\\is'N W
s e
N ss O
/
BUILDING 2 4
I O
- %g b
N h
h l
l h
NOT TO SCALE FIGURE 1: General Atomics Facility Indicating Location of Building 2 0
h:\\essap\\ reports \\ general.ato\\ gen _ atom.003 General Atomics (655)-October 28,1996 l
655-012 (x) i l
i b
s s
jan; g j
Sco
- 837..
518 Cog
.g-f gf ;.,.,
LAB A
/
k (2
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SECTION A BUILDING 2 N
h J L
-.% GROUP 8B LABS NOT SURVEYED T
SURVEYED AREA d
NOT TO SCALE FIGURE 2: Building. 2 - Group 88 Laboratories 9
h:\\essap\\ reports \\ general.ato\\ gen _ atom.003 General Atomics (655)-October 28,1996
'655-001 (1)
>1 e
4 508A 506A y
2 O
O 8
G S
y A
- 9 e
f.J 508 506 3
1
+
g 0
9 Y
MEASUREMENT / SAMPLING LOCATIONS x*N or
$ SINGLE-PolNT FLOOR ELEVATED DIRECT E
A SINGLE-POINT LOWER WALL RADIATION O
3 m
O METERS '
h MISCELLANEOUS SAMPLE 4 EXPOSURE RATE l
FIGURE 3: Building 2 Rooms 506, 506A, 508, 508A - Measurement and Sampling Locations Gener,I Atomics (655)- October 28,1996 10 n:s
.pm,t,s,,,,,,i. ios,,,,,om.oo3
l
- 655-003(1)
SERVICE CORE O A O
6 9
g 4
0 5
9 O
1 Y
HALLWAY MEASUREMENT /SAMPUNG N
LOCATIONS
$ SINGLE-POINT FLOOR A SINGLE-POINT LOWER WALL FEET o
3 4' EXPOSURE RATE N
o METERS FIGURE 4: Building 2, Rooms 519/521 - Measurement and Sampling Locations 11 General Atcnnica (f 55)- October 28,1996 hkssap\\ reports \\ general.ato\\g en_stom.003
655-005 (1)
SERVICE CORE 10 4
9 8
4 9
9 O
6 8
.g 9
9 Y
HALLWAY MEASUREMENT /SAMPUNG LOCATIONS at g, or
$ SINGLE-POINT FLOOR FEET A SINGLE-POINT LOWER WALL U
@f EXPOSURE RATE FICURE 5:
Building 2, Rooms 635 - Measurement and Sampling Locations General Atomics (655)-October 28,19%
1 h Mssapuports\\genemt.atoigen_ atom.003
655-007(1)
SERVICE CORE A
_6 9
e 0
a 9
j i
LAB 637 LAB 639 4
i O
9 13 l
l l
4 12 4
O e
e HALLWAY MEASUREMENT /SAMPUNG LOCATIONS y _ x
'or g SINGLE-POINT FLOOR FEET 0
3 A SINGLE-POINT LOWER WALL M
0
$ EXPOSURE RATE FIGURE f,:
Building 2. Rooms 637/639 - Measurement and Sampling Locations 13 Gener.1 Atomics (655) October 28,1996 a:s.,,,ps,,po,1,1,,,,,,i..ios,,,,,om.oo3
655-009 (1) i HALLWAY l
e 9
15 l
14 i
4 16 g
9 l
O i
e O
~9 DPEN TO LABS 635/637/639 MEASUREMENT /SAMPUNG LOCATIONS x
y air --
g SINGLE-POINT FLOOR 0
6 A SINGLE-POINT LOWER WALL M
l
- fEXPOSURERATE l
FIGURE 7:
Building 2, Mezzanine above Rooms 637/639 - Measurement and Sampling Locations 14 General Atomics (655)-October 28,1996 h k ssap'<eportsigeneral.at oigen_ atom.003
~
TABLE 1
SUMMARY
OF SURFACE ACTIVITY LEVELS OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA Ange of Removable Number Range of Total Activity Activity 2
Location' Measurement dp/100 m )
2 (dpm/100 cm )
Location t
Alpha Beta Alpha Beta 13 floor
<52
<310-830
<14
<16 Labs 506/506A/508/508A 7 Lower wall
<29
<260-1,700
<14
<16 1
6 floor
<52
<310
<14
<16 Labs 519/521 4 Lower wall
<29
<290
<14
<16 7 Boor
<52
<310
<14
<16 Lab 635 2 Lower wall
<29
<290
<14
<16 12 Hoor
<52
<310
<14
<16 Lab 637/639 4 Lower wall
<29
<290
<14
<16 10 Door
<29
<260
<14
<16 Mezzanine 635/637/639 1 Lower wall
<29
<290
<14
<16 4
'See Figures 3 through 7 i
J General Atonucs(655). October 28,1M 15 nu pveport.seneralatosen tom.oo3
l' l
l I
TABLE 2 i
EXPOSURE RATES I
OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS I
SAN DIEGO, CALIFORNIA Location
- Exposure Rate Measurement (gR/hr) l Labs 506 #1 13 i
Lab 506A #2 16 Lab 508 #3 15 Labs 519/521 #5 15 Labs 519/521 #6 17 Labs 519/521 #7 14 Lab 635 #8 13 Lab 635 #9 12 i
Lab 635 #10 11 Labs 637/639 #11 14 Labs 637/639 #12 14 Labs 637/639 #13 14 Mezzanine #14 12 Mezzanine #15 11 Mezzanine #16 13
'See Figures 3 through 7.
I l
Ib hWegeriaratatogen,, atom 003 General Atonucs (655)- October 28, IW
i i
REFERENCES l
[
General Atomics (GA). Decontamination of Selected General Atomics' Science Laboratories for Release to Unrestricted Use (Group 8B). August 23,1996.
i Oak Ridge Institute for Science and Education. Radiological Survey for the Group 6 Laboratories, Building 2, General Atomics, San Diego, California. Oak Ridge, TN; May 1995a.
Oak Ridge Institute for Science and Education Survey Procedures Manual for the i
Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 9. Oak Ridge, Tennessee; April 30,1995b.
I Oak Ridge Institute for Science and Education.
Quality Assurance Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program,
)
Revision 7. Oak Ridge, Tennessee; January 31,1995c.
Oak Ridge Institute for Science and Education.
Laboratory Procedures Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 9. Oak Ridge, Tennessee; January 31,1995d.
Oak Ridge Institute for Science and Education (ORISE). Confirmatory Survey Plan for Building 2, Group 8B Laboratories, General Atomics, Sar: Diego, California. Oak Ridge, Tennessee; September 1996.
U.S. Nuclear Regulatory Commission (NRC). Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of License for Byproduct, Source, or Special Nuclear Material. Washington, DC: NRC; August 1987.
U.S. Nuclear Regulatory Commission. Policy and Guideline Directive FC91-2, Standard Review Plan: Evaluating Decommissioning Plans for Licenses Under 10 CFR Parts 30, 40, and 70.
Washington, DC: NRC; August 1991.
i i
17 h%:sapireponsigeneral stogen,,,atorn 003 General Atonucs(65$) Ch. cber 28,1996 1
APPENDIX A MAJOR INSTR UMENTATION i
1 i
I General Atomics (655). October 28,1996 h%ssapVeponsteneral.stoigen_ atom _003 1
I 5
I 4
~
APPENDIX A
' MAJOR INSTRUMENTATION l
The display of a specific product is not to be construed as an endorsement of the product or its i
manufacturer by the authors or their employer.
l DIRECT RADIATION MEASUREMENT Instruments a
Eberline Pulse Ratemeter Model 12 (Eberline, Santa Fe, NM) l Ludlum Floor Monitor Model 239-1 (Ludlum Measurements, Inc.,
Sweetwater, TX)
Ludlum Ratemeter-Scaler Model 2221 (Ludlum Measurements, Inc.,
Sweetwater, TX)
Detectors Eberline GM Detector I
Model HP-260 2
Effective Area,20 cm
' (Eberline, Santa Fe, NM) l I
Ludlum Gas Proporticnal Detector Model 43-37 2
Effective Area,550 cm (Ludlum Measurements, Inc., Sweetwater, TX) i Ludlum Gas Proportional Detector Model 43-68 Effective Area,126 cm2 (Ludlum Measurements, Inc., Sweetwater, TX)
A-1 hw pwpon.,
a.iog _.w.w3 General Atonucs (655). October :8. lu
~ -.. - - -.. -
l-l Bicron Micro-RemMeter.-
Tissue Equivalent Survey Meter 1
- (Bicron Corporation, Newberry, OH) l:
Victoreen NaI Scintillation Detector l
Model 489 {
l 3.2 cm x 3.8 cm Crystal
)
(Victoreen, Cleveland, OH)
)
LABORATORY ANALYTICAL INSTRUMENTATION I
l
. Low Background Gas Proportional Counter i
l
. Model LB-5100-W l
(Oxford, Oak Ridge, TN)
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l APPENDIX B SURVEY AND ANALYTICAL PROCEDURES
)
1 i
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i General Atormes(655) October 28, t996 h kssapVeports\\ general stogen. atom 003
l APPENDIX B SURVEY AND ANALYTICAL PROCEDURES SURVEY PROCEDURES i
Surface Scans Surface scans were performed by passing the detectors slowly over the surface; the distance between the detector and the surface was maintained at a minimum-nominally about I cm. A large surface area, gas proportional floor monitor was used to scan the floors of the surveyed areas. Other surfaces were scanned using small area (20 cm or 126 cm ) hand-held detectors. Identification of elevated 2
2 levels was based on increases in the audible signal from the recording and/or indicating instrument.
Combinations of detectors and instruments used for the scans were:
Alpha gas proportional detector with ratemeter-scaler ZnS scintillation detector with ratemeter-scaler gas proportional detector with ratemeter-scaler Beta' GM detector with ratemeter-scaler Gamma NaI scintillation detector with ratemeter Surface Activity Measurements Measurements of total beta activity levels were primarily performed using gas proportional detectors with ratemeter-scalers.
Count rat.s (cpm), which were integrated over 1 minute in a static position, were converted to 2
activity levels (dpm/100 cm ) by dividing the net rate by the 4 n efliciency and correcting for the active area of the detector. Because different building materials (poured concrete, concrete block, metal, wood, etc.) can have very different background levels, average background counts were B-1 hwwgynnt %en_somm3 General Atarmes(655). October 28, tu
determined for each material encountered in the surveyed area at a location of similar construction and having no known radiological histog. The beta activity background count rates for the gas proponional detectors averaged 618 cpm for poured concrete,430 cpm for sheet rock, and 524 cpm for cinder block. Alpha background count rates for the gas proportional detectors averaged 5 cpm for poured concrete,1 cpm for sheet rock and 1 epm for cinder block. Net count rates were determined by subtracting the appropriate material background from the gross count rate for each measurement location. The beta efliciency factor was 0.29 for the gas proportional detector calibrated to TI-204. The beta minimum detectable concentrations (MDC) for the gas proportional 2
detectors varied by material and ranged from 260 to 310 dpm/100 cm. The alpha efficiency factor was 0.2 for the gas proportional detectors calibrated to Th-230 and MDCs ranged from 30 to 50 2
2 dpm/100 cm. The physical window area for the gas proportional detectors is 126 cm,
Removable Activity Measurements Removable activity levels were determined using numbered filter paper disks,47 mm in diameter.
I 2
Moderate pressure was applied to the smear and approximately 100 cm of the surface was wiped.
Smears were placed in labeled envelopes with the location and other pertinent information recorded.
Exposure Rate Measurements Measurements of gamma exposure rates were performed using a microrem meter. The instrument was held at one meter above the surface. The measurement was read directly in pR/h.
ANALYTICAL PROCEDURES Gross Alpha / Beta
- Smears were counted on a low-background gas proportional system for gross alpha, and gross beta activity.
B-2 av pvepo,i,s.,.i.io1,,o_.iom oo3 General Atormca (655). October 28. im
UNCERTAINTIES AND DETECTION LIMITS The uncertainties associated with the analytical data presented in the tables of this repon represent the 95% confidence level for that data. These uncertainties were calculated based on both the gross sample count levels and the associated background count levels. Additional uncertainties, associated with sampling and measurement procedures, have not been propagated into the data presented in this report.
Detection limits, referred to as minimum detectable concentration (MDC), were based on 2,71 plus 4.65 times the standard deviation of the background count [2.71 + 4.65/BKG]. When the activity was determined to be less than the MDC of the measurement procedure, the result was reported as j
less than MDC. Because of variations in background levels, measurement efficiencies, and contributions from other radionuclides in samples, the detection limits differ from sample to sample and instmment to instrument.
CALIBRATION AND QUALITY ASSURANCE Calibration of all field and laboratory instrumentation was based on standards / sources, traceable to NIST, when such standard / sources were available. In cases where they were not available, standards of an industry recognized organization were used.
Analytical and field survey activities were conducted in accordance with procedures from the following documents of the Environmental Survey and Site Assessment Program:
Survey Procedures Manual, Revision 9 (April 1995)
Laboratory Procedures Manual, Revision 9 (January 1995)
+
Quality Assurance Manual, Revision 7 (January 1995)
B-3 a se gw po,s s, n,.i.to
_. tom 003 s
Gener.1 Atonucs (655). Octobe, 28,1 M
The procedures contained in these manuals were developed to meet the requirements of DOE Order 5700.6C and ASME NQA-1 for Quality Assurance and contain measures to assess processes during their performance.
Quality control procedures include:
Daily instrument background and check-source measurements to confirm that equipment operation is within acceptable statistical fluctuations.
Participation in EPA and EML laboratory Quality Assurance Programs.
Training and certification of all individuals performing procedures.
Periodic internal and external audits.
B-4 hwpvepon genera togevt=w)
General Atorrues(655). October 28,1M
i 1
)
APPENDIX C GUIDELINES FOR DECONTAMINATION OF FACILITIES AND EQUIPMENT PRIOR TO RELEASE FOR UNRESTRICTED USE OR TERMINATION OF LICENSES FOR BYPRODUCT, SOURCE OR SPECIAL NUCLEAR MATERIAL U. S. Nuclear Regulatory Commission Division ofFuel Cycle & Matenal Safety Washington, D.C. 20555 j
August 1987 General Atonucs(653). October 28.1996 h kasapVeports general ato%en_ atom.003
4-A e
The instructions in this guide, in conjunction with Table 1, specify the radionuclides and radiation exposure rate limits which should be used in decontamination and survey of surfaces or premises and 4
equipment prior to abandonment or release for unrestricted use. The limits in Table 1 do not apply to premises, equipment, or scrap containing induced radioactivity for which the radiological considerations pertinent to their use may be different. The release of such facilities or items from regulatory control is considered on a case-by-case basis.
1 1.
The licensee shall make a reasonable effort to eliminate residual contamination.
2.
Radioactivity on equipment or surfaces shall not be covered by paint, plating, or other covering i
material unless contamination levels, as determined by a survey and documented, are below the a
l' limits specified in Table 1 prior to the application of the covering. A reasonable effort must be made to minimize the contamination prior to use of any covering.
3.
The radioactivity on the interior surfaces of pipes, drain lines, or ductwork shall be determined j
by making measurements at all traps, and other appropriate access points, provided that contamination at these locations is likely to be representative of contamination on the interior j
of the pipes, drain lines, or ductwork. Surfaces or premises, equipment, or scrap which are likely to be contaminated, but are of such size, construction, or location as to make the surface 1
inaccessible for purposes of measurement, shall be presumed to be contaminated in excess of the limits.
4.
Upon request, the Commission may authorize a licensee to relinquish possession or control of premises, equipment, or scrap having surfaces contaminated with materials in excess of the limits specified. This may include, but would not be limited to special circumstances such as razing of buildings, transfer from premises to another organization continuing work with radioactive materials, or conversion of facilities to a long-term storage or standby status. Such requests must:
C-I h Vssapveports' general aidgen_ atom.003 Ocneral Atomics (655). October 28. Im
Provide detailed, specific information describing the premises, equipment or, scrap, a.
radioactive contaminants, and the nature, extent, and degree of residual surface contamination.
b.
Provide a detailed health and safety analysis which reflects that the residual amounts of materials on surface areas, together with other considerations such as prospective use of the premises, equipment, or scrap, are unlikely to result in an unreasonable risk to the health and safety of the public.
5.
Prior to release of premises for unrestricted use, the licensee shall make a comprehensive radiation survey which establishes that contamination is within the limits specified in Table 1.
A copy of the survey report shall be filed with the Division of Fuel Cycle, Medical, Academic,
)
and Commercial Use Safety, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, j
and also the Administrator of the NRC Regional Office havingjurisdiction. The report should be filed at least 30 days prior to the planned date of abandonment. The survey report shall:
a.
Identify the premises.
. b.
Show that reasonable effort has been made to eliminate residual contamination.
c.
Describe the scope of the survey and general procedures followed.
d.
State the findings of the survey in units specified in the instruction.
Following review of the report, the NRC will consider visiting the facilities to confirm the survey.
C-2 hwapveports' general ato%en_atont003 General Atormes (655). October 28. IM
_.~
TABLE 1 ACCEPTABLE SURFACE CONTAMINATION LEVELS p
k EI Nuclides*
Average Af Maximum df Removable ^f 6
6 b
associated decay products 5,000 dpm d100 cm 15,000 dpm n/100 cm 1,000 dpm d100 cm 2
2 2
tr
~
C Transuranics, Ra-226, Ra-228, 3
2 2
Ac-227, I-125, I-129 100 dpm/100 cm 300 dpm/100 cm 20 dpm/100 cm Th-nat, Th-232, Sr-90, Ra-223, 2
2 2
Ra-224, U-232, I-126, I-131, I-133 1,000 dpm/100 cm 3,000 dpm/100 cm 200 dpm/100 cm Beta-gamma emitters (nuclides with decay modes other than alpha emission
{
or spontaneous fission) except Sr-90 2
2 2
and others noted above.
5,000 dpm py/100 cm 15,000 dpm py/100 cm 1,000 dpm py/100 cm
'Where surface contamination by both alpha-and beta-gamma-emitting nuclides exists, the limits established for alpha-and beta-gamma-emitting nuclides should apply independently.
6As used in this table, dpm (disintegrations per minute) means the rate of emission by radioactive material as determined by correcting the counts per minute observed by an appropriate detector for background, efficiency, and geometric factors associated with the instrumentation.
- Measurements of average contaminant should not be averaged over more than I square meter. For objects ofless surface area, the
[
average should be derived for each such object.
}
dThe maximum contamination level applies to an area of not more than 100 cm,
2
}
The amount of removable radioactive material per 100 cm of surface area should be detemiined by wiping that area with dry filter 2
i or soft absorbent paper, applying moderate pressure, and assessing the amount of radioactive material on the wipe with an appropriate h
instrument of known efficiency. When removable contamination on objects ofless surface area is determined, the pertinent levels
{
should be reduced proportionally and the entire surface should be wiped.
'g
'The average and maximum radiation levels associated with surface contamination resulting from beta-gamma emitters should not y
exceed 0.2 mrad /h at I cm and 1.0 mrad /h at 1 cm, respectively, measured through not more than 7 milligrams per square centimeter of total absorber.
u-CONFIRMATORY SURVEY OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA Prepared by i
E. W. Abelquist and T. L. Bright Environmental Survey and Site Assessment Program Environmental and Health Sciences Division i
Oak Ridge Institute for Science and Education Oak Ridge, Tennessee 37831-0117 Prepared for the Division of Fuel Cycle Safety and Safeguards U.S. Nuclear Regulatory Commission DRAFT REPORT OCTOBER 1996
. This draft report has not been given full review and patent clearance, and the dissemination of its information is only for official use. No release to the public shall be made without the approval of the Office of Information Services, Oak Ridge Institute for Science and Education.
j This report is based on work performed under contract number DE-AC05-760R00033 with the U.S.
Depanment of Energy.
General Atornics(655). October 28.1996 hMasapVeports' general stoi en_ atom 003 s
L
t.
ACKNOWLEDGMENTS 4
The authors would like to acknowledge the significant contri5utions of the following staff members:
FIELD STAFF T.
L.
Bright LABORATORY STAFF -
R.
D.
Condra 1.
S.
Cox M.
J Laudeman S.
T.
Shipley CLERICAL STAFF D.
K.
Ash T.
S.
Fox.
K.
E.
Waters ILLUSTRATOR T.
L.
Bright General Atomics (655).0ctober 28,1996 hnessapVeportsgeneral atogen_stom 003
- g i
TABLE OF CONTENTS PAGE
' List of Figures...
.... ii List of Tables.
iii Abbreviations and Acronyms iv
. Introduction and Site History..........
.1 Site Description.
.2~
, Objective.
2 i
)
' Document Review '....
.2 i
Procedures.......
.2 I
Findings and Results
.5 Comparison of Results with Guidelines.
..6 1
Summary.....
.7 i
i References........
. 17 Appendices:
Appendix A: Major Instmmentation Appendix B: Survey and Analytical Procedures Appendix C: Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of Licenses for Byproduct, Source i
l 1
4 r
l L
l I-General Atomics (635). October 28,1996 I
hiessapveportsgeneral.ato\\ gen,atorrt003 l
- r l
1 LIST OF FIGURES 4
f PAGE FIGURE 1:
General Atomics Facility Indicating Location of Building 2.
.8
. FIGURE 2:
Building 2-Group 8B Laboratories....
.9 j
FIGURE 3:
Building 2, Rooms 506, 506A, 508, 508A-Measurement and Sampling Locations 10 FIGURE 4:
Building 2, Rooms 519/521-Measurement and Sampling Locations I1 FIGURE 5:
Building 2, Room 635-Measurement and Sampling Locations 12 FIGURE 6:
Building 2, Rooms 637/639-Measurement and Sampling Locations..
.- 13 FIGURE 7:
Building 2, Mezzanine above Rooms 637/639-Measurement i
and Sampling Locations................
. 14 I
i i
i hhp'reportsgeneral.atogen, atom.003 General Atomics (655). October 28. t996 4
,,n
l LIST OF TABLES PAGE TABLE 1:
Summary of Surface Activity Levels.
15 TABLE 2:
Exposure Rates
. 16 i
I General Atomics (655). October 22.1996 hhap'veports' general atogen atorn003
. ~.
ABBREVIATIONS AND ACRONYMS i
pR/h microroentgens per hour ASME American Society ofMechanical Engineers cm-centimeter 2
cm square centimeter cpm counts per minute DOE Department ofEnergy l
dpm/100 cm disintegrations per minute per 100 square centimeters 2
EML Environmental Measurements Laboratory EPA Environmental Protection Agency ESSAP Environmental Survey and Site Assessment Program GA General Atomics GM Geiger-Mueller ha hectare km kilometer m
. meter -
2 m
square meter MDC Minimum Detectable Concentration
[
NaI sodium iodide j
NIST '
National Institute of Standards and Technology 2
NRC Nuclear Regulatory Commission ORISE Oak Ridge Institute for Science and Education pCi/g picoeuries per gram ZnS zinc sulfide General Atomics (655) October 28,1996 kV h%ssapVeportsigenent stobn_aum003
1 CONFIRMATORY SURVEY OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS i
SAN DIEGO, CALIFORNIA
'l l
INTRODUCTION AND SITE IIISTORY General Atomics (GA) has been in the proe w of decommissioning and obtaining the release for unrestricted use for a number of selected laboratories and associated offices in GA's Building 2 (also known as the Science Laboratories Building or "L" Building). Building 2, built in 1958, was used to conduct research and developmental activities. Activities involving radioactive material included
. scanning electron microscopy and x-ray diffraction on uranium and thorium samples, assembly of irradiation capsules containing enriched uranium, U-238, and thorium, and analysis of nuclear fuel elements. GA is licensed by the Nuclear Regulatory Commission (NRC) under license SNM-696, Docket 70-734. The facility is also licensed by the State of California.
Decommissioning efforts began in 1988 with a block oflaboratories known as " Group 1" To date, approximately eight groups oflabs have been decontaminated and released for unrestricted use. GA has recently performed a final status survey for another group of 11 laboratories in Building 2, identified as the " Group 8B" laboratories (GA 1996). The primary radionuclides used in these laboratories were uranium (including enriched uranium) and thorium. In the past, many of these laboratories were decontaminated and then used for non-radiological purposes.
At the request of the NRC's Division ofFuel Cycle Safety and Safeguards, the Environmental Survey and Site Assessment Program (ESSAP) of the Oak Ridge Institute for Science and Education (ORISE) performed a confirmatory survey of the Group 8B labs. ESSAP performed a radiological survey of the Group 6 laboratories of Building 2 in February 1995 (ORISE 1995a).
)
a General Atorrucs (655). October 28.1996 hkssapVeportsgeneral.atogen_atorrt003
l SITE DESCRIPTION i-
)
l l
The GA facilities are located near the mtersection ofInterstate 5 and Genesee Avenue in San Diego, California (Figure 1). Building 2 is divided into three laboratory sections: Laboratories A, B, and C.
Alllaboratories in Group 8B are located in laboratory section A (Figure 2). The eleven laboratories 2
2 and one mezzanine consist of a total area of about 350 m. The labs range in size from 10 m to 60
~
2 2
m, while the mezzanine for labs 635,637, and 639 has an area of 62 m. The labs are designated:
506, 506A, 508, 508 A, 515, 519/521 (combined lab), 523, 530/532, 635, 637/639, and the mezzanine for labs 635 and 637/639. The wall surfaces consist of standard construction materials such as 4
cement block, plasterboard, drywall, and wood. Some of the walls are painted and the floors are typically poured concrete. Tile was removed from the floor in some labs by the licensee to facilitate 3
j the final status survey.
2 i
l OBJECTIVES l
The objectives of the confirmatory survey are to provide independent contractor field data reviews and radiological data for use by the NRC in evaluating the adequacy and accuracy of the licensee's procedures and final status survey results.
1 DOCUMENT REVIEW i
i ESSAP has reviewed the licensee's final status survey report (GA 1996). Procedures and methods used by the licensee were reviewed for adequacy and appropriateness. The data were reviewed for accuracy, completeness, and compliance with guidelines.
7 2
M PROCEDURES i
i i
s ESSAP personnel performed visual inspections and independent measurements and sampling of the Group 8B laboratories on September 16 and 17,1996. Survey activities were conducted in i
accordance with a site-specific survey plan (ORISE 1996), using procedures and instruments described in the ORISE/ESSAP Survey Procedures and Quality Assurance Manuals (ORISE 1995b 2
hkssapveportsgeneral atogen_storrLOO3 Ocneral Atomics (655). October 28. Im s
1 l
and c) and summarized in Appendices A and B. Rooms 506,506A,508,508A,519/521 (combined),
635,637/639, and the mezzanine were selected for confirmatory survey. This report summarizes the procedures and results of the smvey.
4 REFERENCE GRID Measurement and sampling locations were referenced to prominent building features (e.g., doorways, j
wall intersections, etc.) and recorded on representative area drawings.
\\
SURFACE SCANS Surface scans for alpha, beta, and gamma activity were performed at a frequency of approximately 1
100 percent of the floors and 10 percent of the lower walls (up to 2 meters). Scans were performed using gas proportional and NaI scintillation detectors coupled to ratemeters or ratemeter-scaler with a
audible indicators.. Locations of elevated direct rediation detected by scans were marked for further investigation.
SURFACE ACTIVITY MEASUREMENTS Background measurements of surface activity on poured concrete, sheet rock and concrete blocks, were performed at building locations that did not have a history of radioactive materials use.
Direct measurements for total alpha and total beta activity were performed at a total of 66 floor and lower wall locations in the surveyed lab areas. In addition, two five-point measurements were 2
performed to determine the 1 m grid block average beta surface activity in room 508. Direct measurements were performed using gas proportional detectors coupled to ratemeter-scalers. A smear sample for the determination of removable gross alpha and gross beta activity was collected at each direct measurement location.
Figures 3 through 7 show measurement and sampling locations.
4 3
s v psrepen.'.co.,.i.ios _.io. oo3 General Atormes(655). October 28. lu
I i
Additional direct measurements were performed at locations of elevated direct radiation identified by surface scans.
l l
EXPOSURE RATE MEASUREMENTS Background exposure rate levels were determined for the building interior at 5 locations of similar construction but without a history of radioactive materials use. Exposure rates were performed at i
a total of 16 locations in the surveyed labs and the mezzanine area. Exposure rate measurements were performed at I m above the floor surface using a microrem meter. Figures 3 through 7 show
)
1 measurement locations.
l MISCELLANEOUS SAMPLING 2
A paint sample was collected from a 100 cm area located off the lower portion of the south wall of 1
l Room 508. Sample location is indicated on Figure 3.
j SAMPLE ANALYSIS AND DATA INTERPRETATION l
Samples and survey data were returned to ORISE's ESSAP laboratory in Oak Ridge, Tennessee for analysis and interpretation. The paint sample was analyzed by gamma and alpha spectrometry and results reported in dpm/100 cm for the paint sample. Direct measurements for surface activity were l
2 2
converted to units of disintegrations per minute per 100 square centimeters (dpm/100 cm ). Smears were analyzed for gross alpha and gross beta activity using a low background gas proportional I
2 l~
counter, and the results converted to units of dpm/100 cm. Exposure rate measurements were i
reported in units of pR/h. The radionuclides ofinterest are uranium and thorium; however, spectra were reviewed for other identifiable photopeaks. Sample analyses were performed in accordance with the ORISE/ESSAP Laboratory Procedures Manual (ORISE 1995d). Additional information conceming major instrumentation is provided in Appendices A and B. Results were compared to the licensee's documentation and NRC guidelines established for release for unrestricted use, which are provided in Appendix C.
4 h%saapveportsgeneral atogen_atont003 General Atomics (655). October 28.1996
a l
FINDINGS AND RESULTS DOCUMENT REVIEW -
j ESSAP reviewed the licensee's radiological survey data and comments were provided verbally to j
the NRC and licensee. The licensee provided responses to those comments. In ESSAP's opinion, the licensee's documentation provided an adequate description of the radiological condition of the i
facility relative to the NRC guidelines for release for unrestricted use.
1 Surface Scans Surface scans identified one area of elevated beta-gamma activity in room 508 (Figure 3).
Surface Activity Levels Surface activity levels are summarized in Table 1. The results of single-point measurements ranged from less than 52 dpm/100 cm for alpha activity and less than 310 to' 1700 dpm/100 cm for beta 2
2 2
activity. Grid block average activity in room 508 was less than 52 dpm/100 cm and 400 to 1,000 2
dpm/100 cm for alpha and beta, respectively. Removable activity levels were less than 14 dpm/100 2
2 cm for gross alpha and less than 16 dpm/100 cm for gross beta.
Exposure Rates Exposure rate measurement data is provided in Table 2 Background interior exposure rates ranged from 13 to 14 pR/h and averaged 14 pR/h. Exposure rates for the surveyed labs and the mezzanine area ranged from 11 to 17 pR/h.
Radionuclide Concentration in Paint The radionuclide concentration in paint was qualitatively assessed to be enriched uranium.
5 m3, ps,.po,i.
n.,.i..togen_ ioraoos General Atomics (655) Octobe,28. tu
2 1
COMPARISON OF RESULTS WITH GUIDELINES l
The primary contaminants of concern for this site are natural thorium and enriched uranium. The applicable NRC guidelines for residual thorium and enriched uranium surface activity levels are (NRC 1987):
Natural thorium 4
2 2
- 1,000 dpm/100 cm, averaged over a 1 m area 2
2 3,000 dpm/100 cm, maximum in a 100 cm area 2
200 dpm/100 cm, removable activity Enriched uranium 5,000 dpm a/100 cm, total, averaged over a 1 m area 2
2 2
2 15,000 dpm a/100 cm, total, maximum in a 100 cm area 2
1,000 dpm a/100 cm, removable activity Direct measurements performed on the south wall oflaboratory 508 exceeded the average guideline 2
for natural thorium-average surface activity measured 1,000 dpm/100 cm (surface activity slightly j
exceeded guideline prior to rounding to two significant figures). After further investigation by the licensee, it was discovered that calibration gamma sources were being stored in the adjacent active laboratory. Direct measurements taken by the licensee before and after the removal of the sources indicate that the sources may be the cause of the elevated measurements. However, a paint sample collected by ESSAP from this area identified that the contamination was due to enriched uranium.
i l
The alpha-to-beta ratio for low enriched uranium may be approximated by a 3:1 ratio; therefore, the 2
corresponding average beta activity guideline may be adjusted to 1,700 dpm/100 cm,
The guideline'for exposure rates measured at 1 m above the surface is 5 pR/h above background 4
(NRC 1991). All exposure rate measurements were within these guidelines.
1 l
I-b b WaapVeportsgeneral.ato%en atom.003 Generat Atormes (655). October 28. IW
1
SUMMARY
The Environmental Survey and Site Assessment Program of the Oak Ridge Institute for Science and Education conducted confirmatory activities for the Group 8B laboratories at the General Atomics Building 2 in San Diego, California. Confirmatory activities included document reviews and on September 16 and 17,1996, ESSAP personr.el visited the site and performed independent surface scans, surface activity measurements, miscellaneous sampling and exposure rate measurements.
The results of the independent confirmatory measurements and sampling supported the conclusions of the licensee's survey, relative to satisfying the guidelines established for this project.
1 7
h \\esupveports' general ato\\ gen.stom 003 General Atarmos(655) October 28. Im
655-011 (x)
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NOT TO SCALE FIGURE 1: General Atomics Facility Indicating Location of Building 2
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655-012 (x) x
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- SURVEYED AREA
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FIGURE 2: Building 2 - Group 88 Laboratories 9
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655-001 (1) e 4
506A 1
508A.
p 2
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MEASUREMENT /SAMPUNG LOCAll0NS ae, > N l
gr
$ SINGLE-POINT FLOOR ELEVATED DIRECT N
A SINGLE-POINT LOWER WALL RADIATION O
3 m
h MISCELLANEOUS SAMPLE METERS '
S EXPOSURE RATE FIGURE 3: Building 2. Rooms 506, 506A, 508, 508A - Measurement and Sampling Locations 10 General Atomics (655). ')ctober 28,19%
nu,,,ps,,,o,,,s,,,,,,i,os,,,,,o. oo3
655-003(1) 1 l
SERVICE CORE eA e
e 4
e 5
l 4
O Y
HALLWAY MEASUPEMENT/ SAMPLING N
LOCATIONS S SINGLE-POINT FLOOR A SINGLE-PolNT LOWER WALL FEET o
3
$ EXPOSURE PKE o
i METERS FIGURE 4: Building 2. Rooms 519/521 - Measurement and Sampling Locations 1I hkssap'veportsveneral.ato\\ gen _ atom 003 General Atomics (655)- October 28,1996
655-005 (1) l l
SERVICE CORE 10 l
e 9
4 l
9 9
b i
l 9
e i
1
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l 8
4 9
l 9
l V
HALLWAY MEASUREMENT /SAMPUNG LOCATIONS x
N*-
-c 7
l
$ SINGLE-POINT FLOOR A SINGLE-POINT LOWER WALL 0
3 m
E METERS '
S EXPOSURE RATE FIGURE 5:
Building 2, Rooms 635 - Measurement and Sampling Locations 12 i,3,,,3yo,en,t,os,,,,,om e General Atomics (655). October 28,im
655-007 (1)
SERVICE CORE A
O e
0 0
0 LAB 637 LAB 639 11 0
9 13 4
4
- 12 O
O 4
O HALLWAY MEASUREMENT /SAMPUNG LOCATIONS x
Nw 7
$ SINGLE-POINT FLOOR FEET 0
3 A SINGLE-POINT LOWER WALL M
E s'
4 EXPOSURE RATE FIGURE 6:
Building 2 Rooms 637/639 - Measurement and Sampling Locations 13 6 wo gv po,,,1,,o., i.ios,,,
,,o
.oo3 Genera l Atomics (655). October 28, ;W
655-009 (1)
HALLWAY i
O O
9 15 g"
16 O
O O
O a
OPEN TO LABS 635/637/639 I
MEASUREMENT /SAMPUNG l
LOCATIONS ac l
or-N
~
g SINGLE-POINT FLOOR FEET O
6 A SINGLE-POINT LOWER WALL m'
-M EXPOSURE RATE FIGURE 7:
Building 2. Mezzanine above Rooms 637/639 - Measurement and Sampling Locations I4 h:\\cssapveportsigeneral.ato\\ gen _ atom 003 General Atomics (655). October 28,1906
TABLE 1
SUMMARY
OF SURFACE ACTIVITY LEVELS OF BUILDING 2, GROUP 8B LABORATORIES I
GENERAL ATOMICS SAN DIEGO, CALIFORNIA Range of Removable Number Range of Total Activity Activity 1
2 Location' Measurement (dpra/100 cm )
2 (dpm/100 cm )
Location Alpha Beta Alpha Beta 13 Door
<52
<310-830
<l4
<l6 Labs 506/506A/508/508A 7 Lower wall
<29
<260-1,700
<14
<16 6 floor
<52
<310
<14
<16 Labs 519/521 4 Lower wall
<29
<290
<14
<16 7 Door
<52
<310
<14
<16 Lab 635 2 Lower wall
<29
<290
<14
<16 12 floor
<52
<310
<14
<16 i
Lab 637/639 4 Lower wall
<29
<290
<14
<16 10 Door
<29
<260
<14
<16 Mezzanine 635/637/639 1 Lower wall
<29
<290
<14
<16
- See Figures 3 through 7.
General Atonucs (655). October 28, IM 15 h se pveporias enermi stos en_stant003 s
s
TABLE 2 EXPOSURE RATES OF BUILDING 2, GROUP 8B LABORATORIES GENERAL ATOMICS SAN DIEGO, CALIFORNIA Location' Exposure Rate Measurement (pR/hr)
Labs 506 #1 13 Lab 506A #2 16 Lab 508 #3 15 Labs 519/521 #5 15 Labs 519/521 #6 17 Labs 519/521 #7 14 Lab 635 #8 13 Lab 635 #9 12 Lab 635 #10 11 Labs 637/639 #11 14 Labs 637/639 #12 14 Labs 637/639 #13 14 Mezzanine #14 12 Mezzanine #15 11 Mezzanine #16 13
- See Figures 3 through 7.
t I
16 n gw.' a mw_.mm3 o,a m.3353 % n. im n
4 REFERENCES General Atomics (GA). I)econtamination of Selected General Atomics' Science Laboratories for Release to Unrestricted Use (Group 8B). August 23,1996.
Oak Ridge Institute for Science and Education. Radiological Survey for the Group 6 Laboratories, Builaing 2, General Atomics, San Diego, California. Oak Ridge, TN; May 1995a.
Oak Ridge Institute for Science and Education. Survey Procedures Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 9. Oak Ridge, Tennessee; April 30,1995b.
Oak Ridge Institute for Science and Education.
Quality Assurance Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 7. Oak Ridge, Tennessee; January 31,1995c.
Oak Ridge Institute for Science and Education.
Laboratory Procedures Manual for the Energy / Environment Systems Division, Environmental Survey and Site Assessment Program, Revision 9. Oak Ridge, Tennessee; January 31,1995d.
Oak Ridge Institute for Science and Education (ORISE). Confirmatory Survey Plan for Building 2, Group 8B Laboratories, General Atomics, San Diego, California. Oak Ridge, Tennessee; September 1996.
U.S. Nuclear Regulatory Commission (NRC). Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of License for Byproduct, Source, or Special Nuclear Material. Washington, DC: NRC; August 1987.
U.S. Nuclear Regulatory Commission. Policy and Guideline Directive FC91-2, Standard Review Plan: Evaluating Decommissioning Plans for Licenses Under 10 CFR Parts 30, 40, and 70.
Washington, DC: NRC; August 1991.
17 h Wup'veponsteneral atogen_stom 003 General Akumes(655) Ocuiber 28, la
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4 APPENDIX A MAJOR INSTRUMENTATION l
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I General Atomics (655)- October 28.1996 h kasapvepons' general atdgen, atom 003
1 I
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APPENDIX A t
MAJOR INSTRUMENTATION l
The display of a specific product is not to be construed as an endorsement of the product or its manufacturer by the authors or their employer.
DIRECT RADIATION MEASUREMENT Instruments i
Eberline Pulse Ratemeter Model 12 (Eberline, Santa Fe, NM)
Ludlum Floor Monitor Model 239-1 l
(Ludlum Measurements, Inc.,
l Sweetwater, TX)
Ludlum Ratemeter-Scaler Model 2221 (Ludlum Measurements, Inc.,
Sweetwater, TX) j Detectors l
Eberline GM Detector Model HP-260 Effective Area,20 cm2 (Eberline, Santa Fe, NM) j l
Ludlum Gas Proportional Detector Model 43-37 2
Effective Area,550 cm (Ludlum Measurements, Inc., Sweetwater, TX)
Ludlum Gas Proportional Detector j.
Model 43-68 2
Effective Area,126 cm 4
(Ludlum Measurements, Inc., Sweetwater, TX) l b
A-1 e p p,n,',en.i.w,,o_ mm Gener.I Atormes(655). October 23,1996 1
. -.. ~
~. - -
. -.. -... ~. -. -. -.. - -.
l 1
j
-1
~Bicron Micro-RemMeter j
~
Tissue Equivalent Survey Meter j
i-
- (Bicron Corporation, Newberry, OH) 1 Victoreen Nal Scintillation Detector i
~ Model 489-55 j
~ 3.2 cm x 3.8 cm Crystal -
}.
(Victoreen, Cleveland, OH) t i
LABORATORY ANALYTICAL INSTRUMENTATION l
Low Background Gas Proportional Counter Model LB-5100-W
- (Oxford, Oak Ridge, TN)
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gv.,o,1,'
- i. ion.iomoos Gener.1 Atomics (655).Ociober 28, IW.
APPENDIX B SURVEY AND ANALYTICAL PROCEDURES 1
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i Gereral Atonuca (655). October 28,1996 h%ssap\\reportsjercral ato%en_ atom 003
L.
1 APPENDIX B SURVEY AND ANALYTICAL PROCEDURES SURVEY PROCEDURES Surface Scans my Surface scans were performed by passing the detectors slowly over the surface; the distance between the detector and the surface was maintained at a minimum-nominally about I cm. A large surface area, gas proportional floor monitor was used to scan the floors of the surveyed areas. Other surfaces 2
2
- were scanned using small area (20 cm or 126 cm ) hand-held detectors. Identification of elevated levels was based on increases in the audible signal from the recording and/or indicating instrument.
Combinations of detectors and instruments used for the scans were:
gas proportional detector with ratemeter-scaler Alpha ZnS scintillation detector with ratemeter-scaler gas proportional detector with ratemeter-scaler Beta GM detector with ratemeter-scaler Gamma NaI scintillation detector with ratemeter Surface Activity Measurements Measurements of total beta activity levels were primarily performed using gas proportional detectors with ratemeter-scalers.
Count rates (cpm), which were integrated over 1 minute in a static position, were converted to 2
activity levels (dpm/100 cm ) by dividing the net rate by the 4 x efficiency and correcting for the active area of the detector. Because different building materials (poured concrete, concrete block, metal, wood, etc.) can have very different background levels, average background counts were B-1 w - p w w.ie,.o_.io oo3 c,
a-c.gss).w-::. iu
)
i determined for each material encountered in the surveyed area at a location of similar construction and having no known radiological history. The beta activity background count rates for the gas proportional detectors averaged 618 cpm for poured concrete,430 cpm for sheet rock, and 524 cpm for cinder block. Alpha background count rates for the gas proportional detectors averaged 5 cpm for poured concrete,' I cpm for sheet rock and I cpm for cinder block. Net count rates were determined by subtracting the appropriate material background from the gross count rate for each measurement location. The beta efliciency factor was 0.29 for the gas proportional detector calibrated to T1-204. The beta minimum detectable concentrations (MDC) for the gas proportional 2
detectors varied by material and ranged from 260 to 310 dpm/100 cm. The alpha efficiency factor was 0.2 for the gas proportional detectors calibrated to Th-230 and MDCs ranged from 30 to 50 -
2 2
dpm/100 cm. The physical window area for the gas proportional detectors is 126 cm,
Removable Activity Measurements Removable activity levels were determined using numbered filter paper disks,47 mm in diameter.
2 Moderate pressure was applied to the smear and approximately 100 cm of the surface was wiped.
Smears were placed in labeled envelopes with the location and other pertinent information recorded.
Exposure Rate Measurements Measurements ofgamma exposure rates were performed using a microrem meter. The instrument was held at one meter above the surface. The measurement was read directly in pR/h.
ANALYTICAL PROCEDURES Gross Aloha / Beta Smears were counted on a low-background gas proportional system for gross alpha, and gross beta activity.
B-2 w p,pon.s,
.i.iow._ com oo3 y
General Atonucs (655). October 28. IM
, _ ~ _ _
UNCERTAINTIES AND DETECTION LIMITS The uncertainties associated with the analytical data presented in the tables of this report represent the 95% confidence level for that data. These uncertainties were calculated based on both the gross sample count levels and the associated background count levels. Additional uncertainties, associated with sampling and measurement procedures, have not been propagated into the data presented in this report.
i Detection limits, referred to as minimum detectable concentration (MDC), were based on 2.71 plus 4.65 times the standard deviation of the background count [2.71 + 4.65/BKG]. When the activity l
was determined to be less than the MDC of the measurement procedure, the result was reported as i
less than MDC. Because of variations in background levels, measurement efficiencies, and e
l contributions from other radionuclides in samples, the detection limits differ from sample to sample i
and instrument to instrument.
1 1
CALIBRATION AND QUALITY ASSURANCE
}
~ Calibration of all field and laboratory instrumentation was based on standards / sources, traceable to NIST, when such standard / sources were available. In cases where they were not available, standards of an industry recognized organization were used, Analytical and field survey activities were conducted in accordance with procedures from the following documents of the Environmental Survey and Site Assessment Program:
l Survey Procedures Manual, Revision 9 (April 1995)
Laboratory Procedures Manual, Revision 9 (January 1995)
Quality Assurance Manual, Revision 7 (January 1995)
B-3 6
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Ocneral Aumcs (655). October 28. IW
The procedures contained in these manuals were developed to meet the requirements of DOE Order 5700.6C and ASME NQA-1 for Quality Assurance and contain measures to assess processes during their performance.
Quality control procedures include:
Daily instrument background and check-source measurements to confirm that equipment
+
operation is within acceptable statistical fluctuations.
Participation in EPA and EML laboratory Quality Assurance Programs.
Training and certification of all individuals performing procedures.
Periodic internal and external audits.
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i b-4 h \\essap\\repons' general.atdgan_stom 003 General Anwruca(655). October 28,19h
4
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APPENDIX C GUIDELINES FOR DECONTAMINATION OF FACILITIES AND EQUIPMENT PRIOR TO RELEASE FOR UNRESTRICTED USE OR j
TERMINATION OF LICENSES FOR BYPRODUCT, SOURCE OR 1
U. S. Nuclear Regulatory Commission J
Division'of Fuel Cycle & Material Safety Washington, D.C. 20555 August 1987 l
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I General Avsmes(655).0ctober 23.1996 h \\essapVeports' general sto\\ gen _atorn003 0
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The instructions in this guide, in conjunction with Table 1, specify the radionuclides and radiation exposure rate limits which should be used in decontamination and survey of surfaces or premises and equipment prior to abandonment or release for unrestricted use. The limits in Table 1 do not apply to premises, equipment, or scrap containing induced radioactivity for which the radiological considerations pertinent to their use may be different. The release of such facilities or items from regulatory control is considered on a case-by-case basis.
1.
The licensee shall make a reasonable effon to eliminate residual contamirmtion.
2.
Radioactivity on equipment or surfaces shall not be covered by paint, plating, or other covering material unless contamination levels, as determined by a survey and documented, are below the limits specified in Table 1 prior to the application of the covering. A reasonable effort must be made to minimize the contamination prior to use of any covering.
3.
The radioactivity on the interior surfaces of pipes, drain lines, or ductwork shall be determined by making measurements at all traps, and other appropriate access points, provided that contamination at these locations is likely to be representative of contamination on the interior of the pipes, drain lines, or ductwork. Surfaces or premises, equipment, or scrap which are likely to be contaminated, but are of such size, construction, or location as to make the surface inaccessible fr r purposes of measurement, shall be presumed to be contaminated in excess of the limits.
4.
Upon request, the Commission may authorize a licensee to relinquish possession or control of premises, equipment, or scrap having surfaces contaminated with materials in excess of the limits i
specified. This may include, but would not be limited to special circumstances such as razing i
of buildings, transfer from premises to another organization ccatinuing work with radioactive materials, or conversion of facilities to a long-term storage or standby status. Such requests must:
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b~I h WasapVepgewal aw en_ atom.003 Genent Atomics (655) Octohe 28.1W s
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Provide detailed, specific information describing the premises, equipment or scrap, a.
radioactive contaminants, and the nature, extent, and degree of residual surface
- contamination.
I b.
Provide a detailed health and safety analysis which reflects that the residual amounts of i
materials on surface areas, together with other considerations such as prospective use of the premises, equipment, or scrap, are unlikely to result in an unreasonable risk to the health and safety of the public.
1
)
5.
Prior to release of premises for unrestricted use, the licensee shall make a comprehensive radiation survey which establishes that contamination is within the limits specified in Table L
~
A copy of the survey report shall be filed with the Division of Fuel Cycle, Medical, Academic, J
and Commercial Use Safety, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, ud also the Administrator of the NRC Regional Office havingjurisdiction. The report should be filed at least 30 days prior to the planned date of abandonment. The survey report shall:
)
3 a.
Identify the premises.
' b.
Show that reasonable effort has been made to eliminate residual contamination.
c.
Describe the scope of the survey and general procedures followed.
d.
State the findings of the survey in units specified in the instruction.
Following review of the report, the NRC will consider visiting the facilities to confirm the survey.
C *7.
hiessapveportsigeneral stoisen, atom 003 Ocneral Atonucs(655).Odober 28.1996
TABLE 1' ACCEPTABLE SURFACE CONTAMINATION LEVELS 3.>
i E
Nuclides*
Average MaximumW Removable *f W
b 3
associated decay products 5,000 dpm a/100 cm 15,000 dpm d100 cm 1,000 dpm a/100 cm 2
2 2
E E
Transuranics, Ra-226, Ra-228, I
2 2
Ac-227, I-125, I-129 100 dpm/100 cm 300 dpm/100 cm 20 dpm/100 cm Th-nat, Th-232, Sr-90, Ra-223, 2
2 2
Ra-224, U-232, I-126, I-131, I-133 1,000 dpm/100 cm 3,000 dpm/100 cm 200 dpm/100 cm Beta-gamma emitters (nuclides with decay modes other than alpha emission
]
or spontaneous fission) except Sr-90 2
2 2
and others noted above.
5,000 dpm py/100 cm 15,000 dpm py/100 cm 1,000 dpm py/100 cm
- Where surface contamination by both alpha-an'd beta-gamma-emitting nuclides exists, the limits establ'ished for alpha-and beta-gamma-emitting nuclides should apply independently.
"As used in this table, dpm (disintegrations per minute) means the rate of emission by radioactive material as determined by correcting the counts per minute observed by an appropriate detector for background, efficiency, and geometric factors associated with the instrumentation.
' Measurements of average contaminant should not be averaged over more than I square meter. For objects ofless surface area, the i
average should be derived for each such object.
2 dThe maximum contamination level applies to an area of not more than 100 cm,
2
'The amount of removable radioactive material per 100 cm of surface area should be determined by wiping that area with dry filter a{
or soft absorbent paper, applying moderate pressure, and assessing the amount of radioactive material on the wipe with an appropriate
[
instrument of known efficiency. When removable contamination on objects ofless surface area is determined, the pertinent levels
{
should be reduced pror.artionally and the entire surface should be wiped.
'g fThe average and max; mum radiation levels associated with surface contamination resulting from beta-gamma emitters should not g
exceed 0.2 mrad /h at I cm and 1.0 mrad /h at I cm, respectively, measured through not more than 7 milligrams per square centimeter of total absorber.
-