ML20155K509

Final Survey Plan for General Atomics Hot Cell Facility Area

ML20155K509
Person / Time
Site:	07000734
Issue date:	10/30/1998
From:	Labonte W GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER
To:
Shared Package
ML20155K476	List: ML20155K474 ML20155K509
References
PROC-981030, NUDOCS 9811130274
Download: ML20155K509 (12)

Text

.. _.

- =.

I i

Final Survey Plan For General Atomic's Hot Cell Facility Area M!50/98

/r hum C n48 Date:

Prepared By:

f l

William T. LaBonte, Health Physicist Approved By:

OJLLACL

&Mh6b Date: /0 30NP

" Laura Q. Gonzales, GA Ffealth Physics Manager l

Approved By:

[N Date: 14 /

u orge U. Brambie'tt," Man'ager, ot Cell Decommissioning Project Approved By: b>

Date: /o/&> /f'f

' '~

Keiih E. Asmussen, Director, Licensing, Safety and Nuclear Compliance 9pg91130274931030C ADOCK 07o00734 C

PDR3

Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 1 of 11 October 30,1998 1.0 Ohlective The objective of the Final Radiological Survey Plan is to provide a plan, which after implementation, will demonstrate that the radiological conditions of General Atomics' (GA's)" Hot Cell Facility Area" meets the NRg and State of California approved criteria for release to unrestricted use. The " Hot Cell Facility Area" includes GA's Building 23 (the Hot Cell Facility), a fenced Hot Cell outside yard and a " footprint" around the fenced yard as shown in Figure 1.

This final radiological survey plan was prepared taking advantage of additional knowledge obtained during the actual decontamination and demolition phases of GA's Hot Cell Facility (HCF) decommissioning effort, and therefore represents a more focused and situation speciGe plan than that discussed in GA's Hot Cell Facility Decommissioning Plan (latest revision dated January 1998). This plan incorporates the necessary and appropriate criteria from Chapter 4 " Planned Final Radiation Survey", of the HCF Decommissioning Plan and integrates it with a five (5) meter triangular grid into a complete stand alone final survey document. Accordingly, this plan supersedes Chapter 4 in specifying how compliance with the release criteria will be demonstrated.

2.0 Site Condition at Time of Final Radiological Survey Prior to the start of the Final Radiological Survey,(1) all building structures and support

]

utilities will have been dismantled and removed, (2) all underground piping system.s, drain lines, support utilities, storage wells and tanks associated with the Hot Cell Facility (HCF) will have been excavated and removed, and (3) all ground coverings, such as asphalt paving or concrete walkways and slabs will have been surveyed, removed and disposed of appropriately. One underground sewer line that traverses the HCF Restricted Area that was never connected to the HCF remains in place. In addition, there are underground sewer lines, fire hydrant piping, storm drains and electrical supply lines traversing a portion of the HCF survey " footprint" outside of, and South of, the HCF Restricted Area that were never associated with the HCF.

Any pits resulting from removal of structures will have been surveyed and the soil sampled prior to back-filling in accordance with a specific Survey Plan. In every instance, the survey will demonstrate that the residual soil and/or fill soil meet the criteria for unrestricted use.

The only surface remaining will be soil which will be surveyed and sampled in accordance with this Plan.

3.0 Background Informatic.n In support of GA's efforts involving predominantly government funded nuclear research and development (R&D), General Atomics (GA) continuously maintained a fully operational Hot Cell Facility (HCF) for over 30 years. Built in 1958 as a heavily shielded

i 1

l Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 2 of 11 October 30,1998 remote-handling laboratory, the Facility supported a wide variety of radiological and investigative operations.

The HCF contained three shielded cells, the Hi,gh Level Cell (HLC), the Low Level Cell (LLC), and the Metallography Cell. The HLC was used to perform destmetive post-irradiation examinations on fuels and structural materials. The LLC served as the staging area for samples being transferred into and out of the HLC. The Metallography Cell was used to prepare irradiated fuel and metal samples (i.e., grinding) for use with the metallograph.

The hot celis were used to perform post-irradiation examinations on fuels, structural materials, and instrumentation for dosimetry. Most of the projects involved examination of irradiated fuel and graphite for High Temperature Gas-Cooled Reactors.

The HCF yard and the service gallery had been used for cask handling and cask maintenance activities, and for waste consolidation, packaging, and characterization (e.g.,

weighing, gamma scanning).

During Decommissioning activities, the HCF was completely dismantled. A substantial portion of the building was disposed of as radioactive waste, including the Cells Manipulator Repair room and Machine shop. All support equipment associated with the HCF, such as underground tanks, wells, and piping systems were excavated and disposed of as appropriate.

Portions of the building which were not directly involved in the handling of radioactive materials, such as the Office Rooms, Change Rooms, Rest Rooms, were dismantled, surveyed and released to unrestricted use. The NRC and State were notified of GA's intent to dispose of these portions for unrestricted use; and the NRC performed confirmatory surveys of portions of the structural materials.

Characterization surveys conducted on the accessible soil surfaces prior to the decommissioning efforts indicated wide spread, low levels of contamination within the Hot Cell Facility Area. The predominant radionuclides, as detected by gamma spectroscopy, were Cs-137, and Co-60 and Cs-134.

4.0 Classification The entire " Hot Cell Facility Area" has been classified as an "Affected area" based on historical knowledge and characterization results and will be surveyed accordingly.

I l

l 5.0 Release Criteria (per G A's NRC-and State approved Hot Cell Decommissionine Plan) l 5.1 Soil Release Criteria l

The soil release criteria to be used are provided in Table 1. Based on historical knowledge, characterization survey data, and soil samples taken to date, the predominant

Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 3 of 11 October 30,1998 contaminants likely to be in the soil within the Hot Cell Facility Area are Cs-137 and Co-

60. The release criteria provided in Table I for these radionuclides have been approved for the GA site since 1985 and applied to many GA Decommissioning Projects. Cs-134, Sr-90 and to a lesser extent other radionuclides noted on the table may also be detected in the soil.

Table 1: Soil and Concrete / Asphalt Rubble Release Criteria '

4 Radionuclide Release Criteria Based on Release Criteria Based on External Exposure Limits, Internal Exposure Limits, i

in pCi/g in pCi/g Co-60 82 Cs-137 15 Cs-134 10 Eu-152 II Eu-154 10 j

Eu-155 635 Nb-94 7.5 Sb-125 37 l

Sr-90 1800 2 Natural Uranium 35 '

Enriched Uranium (U-235 & U-234) 30' Thorium (Th-232 & Th-228) 10' 8

The release criteria shown in this table without annotation by footnotes 2 or 3 were calculated by the licensee using RESRAD version 5.18 adhering to the same assumptions that were provided in the correspondence listed in note 2 below. This corresponds to conservative calculation of the homogenous concentration of an isotope in the soil that by itself would give approximately 10 pR/hr external exposure rate above background for the maximum year of exposure.

2 These release criteria are based upon precedent through NRC and State of California approved release limits for the GA site. See correspondence K. E. Asmussen to W. T. Crow, dated October 1,1985, correspondence identification 696-8023,

Subject:

" Docket 70-734: Plan for Obtaining Release of Certain Areas to Unrestricted Use."

3 These release criteria are based on past precedent established by NRC through NRC Policy Issue SECY-81 576, dated October 5,1981, Subject " Disposal or on-site storage of residual thorium or uranium (either as natural ores or without daughters present) from past operations."

4 If additional nuclides are encountered during the Final Survey activities values identified in the previously approved GA Hot Cell Facility Decommissioning Plan and the GA Site Decommissioning Plan will be used.

l

{

i

\\

t i

Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 4 of 11 October 30,1998 l

i In situations where more than one isotope is detected in the soil, determination of conformance to release criteria will be made according to the following method for the mixture:

C / G + C / G +...+ C,/ G, s 1 i

i 2

2 l

Where:

C, C _, is the concentration of nuclide 1,2,...n in the soil above background values 2

G, G,..., is the release criteria of nuclide 1,2,...n i

2 It is GA's intent to remediate areas containing elevated activity levels in the soil.

However,in the event that reasonable efforts have been made and soil concentrations continue to remain elevated, GA may apply the criteria described in section 2.2 and i

section 8.0 of the manual referenced below to determine compliance. Section 2.2 and section 8.0 of the manual specifies that areas of residual activity exceeding the guideline value, known as " elevated" areas, are acceptable, provided they do not exceed the guideline value by greater than a factor of(100/A)", where A is the area of residual 2

activity in m, and provided the activity level at any location does not exceed three times the guideline values. In addition, radionuclide concentrations will be averaged to demonstrate the average is at or below guideline values, established as acceptable to 2

NRC. Averaging will be based on a 100 m (10 m x 10 m) grid.

l 5.2 Exposure Rate Criteria The release criteria for direct gamma scans is 10 pR/hr above background measured at Im from the surface. Typically a background exposure rate of 15 R/hr measured at I m above the ground surface is measured in unaffected areas using a microR meter.

For open land areas, exposure rates (measured at I m above the surface) can be averaged 2

over 100 m grid areas. The maximum exposure rates over any discrete area may not exceed two times the limit above background in accordance with section 2.2 and section 8.0 of the manual referenced below'. It is GA's intent to remediate all areas where microR readings exceed 10 microR/hr at I m above the surface. However, in the event that reasonable efforts have been made and measurements continue to remain elevated, GA may apply the criteria described above to determine compliance.

6.0 Measurements for Demonstratine Compliance with Release Criteria l

6.1 Backaround Concentrations

' Manual for Conducting Radiological Surveys in Support of License Termination (Draft for Comment),

NUREG/CR-5849, ORAU-92/C57, Oak Ridge Associated Universities. June 1992.

Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 5 of 11 October 30,1998 The soil release criteria are concentrations above natural background concentrations.

Typical background concentrations for various types of media are provided below:

Typical soil concentrations are provided in the table below which represent the average results of seventeen (17) surface soil samples and ten (10) concrete samples collected in undisturbed areas from off site locations in the region surrounding the GA site.

Aledia Type Cs 137 U 238 U-235 Th-232 (pCUR)

(pCUg)

(pCUg)

(pCUg)

Soil 0.21 0.20 1.2620.78 0.08 0.04 1.72 0.92 Concrete 0.04 t0.02 4.27 0.63 0.1220.03 3.62 0.24 6.2 Surface Soil Samples Scanning (along the surface of the soil) will be performed to identify locations of elevated activity levels. Areas of suspected activity, identified by scanning or visual inspection, will be evaluated to determine their activity levels and the extent of contamination.

Cleanup will be performed, as required, and the scanning repeated until remediation is accomplished as demonstrated by additional soil sampling, analysis and comparisons with the guidelines, l

After scanning and remediation of known contaminated areas, grids will be established for the purpose of referencing the locations of samples and measurements taken during l

implementation of this final survey plan. The 10 m x 10 m grid system to be used is shown in Figure 2.

Systematic surface (0-6") soil sampling will be performed on a triangular grid with a l

sampling interval of 5 m on a side as shown in Figure 2. The 5 m triangular grid includes i

sampling from underneath the previous Hot Cell Facility concrete pad and the outside storage yard within the radiation restricted area fence and in the area surrounding the i

restricted area. Additional remediation (and subsequent sampling) will be conducted if

(

the release criteria are not met. A total of about 330 surface soil samples will be collected.

l The 5 m triangular grid scheme used in this plan was previously used in the GA's SVA Decommissioning Project (HTGR Fuel Manufacturing Facility).

i Biased samples will also be collected from underneath former concrete slabs where the soil appears affected; i.e., discolored, odiferous or otherwise abnormal or suspected of contamination.

6.3 Subsurface Soil Samples i

Remediation of soil, if necessary, will continue to a depth required to reduce the l

l l

Final Radiological Survey Plan for General Atomics'_ Hot Cell Facility Area L

Page 6 of 11 October 30,1998 l

l concentrations to levels below the release criteria. A final sample (s) after remediation will demonstrate that residual activity is below the release criteria.

Subsurface samples may be collected to a depth of one (1) to three (3) feet or more; depending on the potential for contamination. ' Subsurface samples will be collected in biased locations and will include: 1) each location (larger than 5 m ) where soil 2

l contamination above the guidelines was discovered and remediated and 2) any location where exposure rate measurements exceed the radiation exposure limit. These measurements will be made using a microR meter or NaI (TI) detector /ratemeter.

In addition, subsurface soil samples (to a minimum depth of 3 feet) will be collected in 23 locations shown in Figure 3 (if subsurface samples were not already collected due to the above criteria). Historical data indicates a potential for subsurface contamination in these locations.

l Subsurface samples may also be collected in other suspect locations, if warranted by exposure rate measurements or remediation efforts.

6.4 Soil Samples Underneath Drain Lines and Undercround Ventilation Ducts When collecting samples from underneath the drain lines (in the trenches created during removal of the drain line), biased samples will be collected as follows:

1)

Soil samples will be collected from underneath and around any drain lines which appear broken, corroded or otherwise deteriorated.

2)

Soil samples will be collected whenever exposure rates are elevated (measured using microR meters and/or Nal(TI) detectors /ratemeters).

3)

Soil samples will be collected if the soil appears affected, i.e., discolored, odiferous or otherwise abnormal.

In addition, systematic samples will be collected approximately every 5 m (about every 15 feet) from underneath former drain lines.

In cases where drain line and ventilation duct removal resulted in pits rather than discrete trenches, the resultant pit (s) will be appropriately sampled (surface and subsurface) to demonstrate that the remaining soil meets the release criteria.

l 6.5 Sample Preparation and Control i

Each soil sample will be properly logged, labeled, packaged and tracked. Approximately I kilogram of soil will be collected for each sample. All debris (grass, rocks, sticks, and foreign objects) will be removed from the sample. Samples will be dried, weighed and counted by gamma spectroscopy. The results of analyses will be reviewed by qualified

Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 7 of 11 October 30,1998 l

GA Health Physics personnel to determine isotopic identification and concentrations.

The GA gamma spectroscopy equipment will be maintained, calibrated and used in accordance with approved GA HP procedures. This analysis may also be performed by l

an approved contracted laboratory having equivalent or better capabilities. Final results will be reported in pCi/g for each applicable ra'dionuclide.

Sr-90 concentrations will be inferred from Cs-137 concentrnions based on information obtained during GA's extensive Characterization Survey. Suected samples will be analyzed by gross alpha / beta to demonstrate that the upper bound on the potential Sr-90 concentration is less than 1800 pCi/g (or well below the sum of the fractions if other radionuclides are present).

6.6 Exposure rate measurements l

The entire Hot Cell Facility Area is identified with the " footprint area" border in Figure 1 The surface of the soil will be scanned using microR meters so that 100% coveraae is l

obtained. Alert levels will be established at levels not to exceed 75% of the release criteria (< 7.5 R/hr above background). Further investigation (which may include soil sampling) will be required when alert levels are exceeded.

To determine compliance with the external radiation limit of 10 microR/hr at I m above the surface, exposure rate measurements will be taken at I meter at all systematic soil sampling locations (after soil remediation has been completed). The results will be compared with the release criteria. A calibrated microR meter will be used to determine exposure rate measurements in microR/hr. Instruments will not be used in conditions that are not in conformance with manufacturer's recommendations.

7.0 Documentation and Ouality Assurance Surveys will be conducted by quali5ed Health Physics technicians having a minimum of 3 years Health Physics Technician experience following approved Health Physics procedures and this plan. The results of these surveys (including the review of gamma spectroscopy results for soil samples) will be reviewed and evaluated by a qualified Health Physicist.

Every exposure rate survey conducted will be documented, on a daily basis, on a drawing showing the approximate locations surveyed. The results will include the appropriate units, the signature of the technician (s) performing the survey, date(s) of survey, instrument (s) used, efficiency, background readings (if appropriate) and any other applicable information, i

(

All soil sample locations will be documented, on,a daily basis, on a drawing indicating the sample location, sample depth, a unique sample identification number, and the l

technician signature, date and time of documentation. In addition, each sample will be controlled by the approved Chain of Custody procedure.

Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area i

Page 8 of 11 October 30,1998 s

A Final Radiological Survey Report will be prepared by GA's Health Physics Group upon completion of the Final Survey. This report will include all survey data and results as well as instrumentation information, including calibration data, instrument efficiencies, minimum detectable activity and background information. This report will include the l

results of final surveys performed in excavation pits.

Sample collection, analysis, and the associated documentation will adhere to written procedures and/or plans and meet the requirements in this plan and GA's NRC and State of California Radioactive Materials Licenses. The Health Physics Laboratory shall maintain a documented Quality Control program and documented calibration records for gamma spectroscopy instrumentation. Quality Assurance staff may audit the laboratory at any time to determine compliance with procedures and plans.

During the conduct of the Final Survey activities, Quality Assurance audits may be performed to verify that Project survey activities comply with established procedures and/or plans. Audit results will be reported to Project Management and corrective actions to resolve any identified deficiencies will be documented, tracked, and verified by the individual conducting the audit.

8.0 Internal GA Confirmatory Surveys Following completion of a " Final Survey", GA normally conducts an additional internal confirmatory survey of facilities and areas to be released to unrestricted use.

Confirmatory measurements of the direct gamma scans of the HCF land areas will be performed by the GA Health Physics Staff who were not involved in the performance of the Final Survey. The results of this survey will also be documented in the Final Radiological Survey Report.

9.0 External Confirmatory Survey Oak Ridge Institute for Science and Education,(ORISE), has been contracted by DOE to perform confirmatory measurements on soil sampling and direct gamma scans.

I l

i I

Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 9 of 11 October 30,1998 Figure 1: Hot Cell Facility Area l

\\

l

\\

.c i

N i

A l

i i

i r.

4 l

I e F l

/~

I l

4 I

b

' /M a

f'n)QnntAnne s

o WASTETANK AREA $

R patx: fed Ares Fence ]

i

.... M._ _.

4..

4..

4 i

/^

f s

__.rv1__._.

. i.... _

{

[

[

1 t.1g_.gp--

r m

o F l

Tk j

. _.k.

k.

s-qs

.p D-y7 4

g

{

\\

7.

1 sumsng 23 j

J F

=

HO". CELL FACRJTY l j

l i

.,..... _ -..,__.~.f.g. -.... _.

[M I

i i

h 8

if

/' y......,

e i

i 6et l

,s

? !

Bp P

f i

1 4

4,,,, 4 4 4 l

f

l Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area Page 10 of 11 October 30,1998 Figure 2: IICF Area Soil Survey Grid Map i

.g.

y g-g-

g-g.

s g.

.g g

\\

1 i

~

1 j

l l

j

..L....

.._ j

. w

....g.

g g

l j

j j

I

[

[,(.. -9 j

j J Am e

g,

....-.g

,,i I

i j

l r

t Am.

< i E

r m

...p

-g g

gy

~~ Js l

4 l

[*

• A*

a f s

yL,._

j. l._..

.l l

l l

P I

1 l

b..

l l

l j

l

}i j

l

,1..., !

[. __. i

'.y m;-' 7 j

l

.l j

s 16 m

V l

..l l

l [ [

j

,a 4

..l.h i

j.i.$

h...-

I I

1

-sr

.I I ;I.I.

l

.I.

s..

t.

g... _$

j j

_...I 3

i i

l-

.y,.

..f.J A

. _. ~ - ~.

s. %.p.

.l

m 4 _.

3............_.. /*yl

{CTCW^oun,,

j

' 7 j

a 1..

r I

j [./ i.

7.~.

l i

ap r

I w-r i

..I...,. s.iM.- no.

I i._

..l j

.s

. h' *^"&

1

.s t

i i

& 37 gtt j

6 Notes:

Five (5) meter tnangular grid sampling pattem

l Final Radiological Survey Plan for General Atomics' Hot Cell Facility Area i

Page 11 cf 11 October 30,1998 l

Figure 3: Subsurface Soil Sample Locations i

l g-g-

g-s g-g-

1 g-6-

'l 3

l i

i N

l l

i i

a A

A I

i I

..l.

...t

_ r A

j t

l i

A A

e f A'

1. 7 l

..._._.4 WTE TAMK AAEA A <

l y

Q

- f 7 f~~~h (1

I

{

_1 L

b

!;r-m i

. 3 gf.

A A

I h

H k,.

l.

A A

(.. _

l*

e,ne,e n a :

woT ces.t rAcouTv, k.l,_...._. l.

f. _..._. }_

.. [

i i

" r

'o

/!

A r-i{

,V

&,f

F b

i "E

A gr.

l t

l A

1

. e a,,,.a e a Twent/ Five (25) locations are planned to be sampled.

A = Sub-surface approximate locations i

1