ML16293A136
Text
WVDP PHAS E 1 DECOMMISSIONING PLAN N
WMA4 ~
WMAS WMA2 Fire Brigade Traini ng Area Vitrification Test Facility Slab Maintenance Shop leach Field lagOOIJJ1
{Deactivated}
WMA1 legend c::::J Wiste Management Area11 Fonner Lagoon c:J Building c:J W.terbodies c:J Coocrele Foundation - ***- Sl1eamsl S10tm¥1l!ler Dr.ainagewa~s
[:J Gravel Pad c::::J AsphaH Road 75 0 75 150 225 300 Feet
-'*- Fence c:J Gravel Road! Pad I I
-+- Ralspur 25 0 25 50 75 100 Meters Figure 3-24. WMA 2. (The facilities to be removed during Phase 1 decommissioning activities include the Neutralization Pit, Interceptors, Lagoons, and remaining slabs.)
Revision 2 3-115
WVDP PHASE 1 DECOMMISSIONING PLAN Figure 3-25. The Low-Level Waste Treatment Facility. (This photo shows the site in 1982, looking toward the southwest. )
Revision 2 3-116
WVDP PHASE 1 DECOMMISS IONING PLAN Figure 3-26. The LLW2 Building that Replaced the 02 Building Figure 3-27. The Lagoon 1 Area. (Radioactive debris was placed in Lagoon 1 when it was closed in 1985.)
Revi sion 2 3-117
WVDP PHASE 1 DECOMMISSIONING PLAN Figure 3-28. The New Interceptors. (These are twin stainless-steel lined concrete holding tanks .)
Revision 2 3-118
WVDP PHASE 1 DECOMMISSIONING PLAN Sh~ued\l.MM. 3r0 ~ JRL N
A IM/JA 2 w.tiA 10 WMA1 Legend c:::J waste Managemenl Areas c::J W.1eJbodies c::J Building - ***- Streams/ Sloonwalet Drainageways CJ Concre1e Foundation c::J Asphall Road 50 0 100 150 F<ince O Gravel Road/ Pad
-+- Ra>>$p<Jr 10 0 10 20 30 40 Meters PVS Pcrmane;nt Y(:_nt 1lalltln S}'5lttn STS SupcmaUUll Treatment S}sttm Figure 3-29. WMA 3. (Facilities to be removed during Phase 1 decommissioning activities include the Equipment Shelter, the condensers , the piping in the HLW transfer trench , and the Con-Ed Building .)
Revision 2 3-119
WVDP PHASE 1 DECOMMISSIONING PLAN Figure 3-30. Aerial View of WMA 3 Area CAllBOH STEEL STORAGE INTERNAL GR OR!( TANll PERLITE BlOC Figure 3-31. Cutaway View of 750-Gallon Underground Waste Tank Revision 2 3-1 20
WVDP PHASE 1 DECOMMISSIONING PLAN
- - - - 1 150 Horsepower Motor I
_ .. _"0111 STAVClU~(
-... ~1 D
1 I
I
- 8 ft f l......,CiW'lf4\.
C>>S'CJroiA~ HGZ.!:t.U 22-inch Diameter Volute II~ I Transfer Pump Mobilization Pump Figure 3-32. HLW Transfer and Mobilization Pumps Revision 2 3-121
WVDP PHASE 1 DECOMMISSIONING PLAN Figure 3-33. HLW Transfer Trench Under Construction Figure 3-34. Typical HLW Pump Pit Revision 2 3-122
WVDP PHASE 1 DECOMMISSIONING PLAN N
A WMA5 IMl.A4
'NMA2 Legend c:JV\laSle Management Areas c::J Watertodies c::J Building - ... Streams/ Stormwaler Drainageways WMA1 CJ Conaete Foundation CJ Asphalt Road t-ence c:::JGravel Road/ Pad
-+- Railspur 75 O 75 150 225 300 Feel Former Lagoon 20 0 20 40 60 80 Meters Figure 3-35. WMA 5. (Facilities to be removed during Phase 1 decommissioning include the Remote-Handled Waste Facility, Lag Storage Addition 4 and its Shipping Depot.)
Revision 2 3-123
WVDP PHASE 1 DECOMM ISSIONING PLAN Figure 3-36. The Remote-Handled Waste Facility. (Placed into service in 2004, th is new building may contain significant contamination at the time it is removed .)
LOAD OUT/TR\JC1< !BAY AlA CLEAN ING UNIT FAN ROOM OFFICE
=
Figure 3-37. The Remote-Handled Waste Facility First Floor Layout.
Revision 2 3-124
WVDP PHASE 1 DECOMMISSIONING PLAN N
A Equa1iza*tion Basin WN'IA 7 WMA 10 WMA 9 c::J was1e Management Areas Former Lagoon CJ Buildlng c::J Waterbocly
[=:J Concrete Foundation - ***- Streams/ Stormwater Drainageways 100 0
[=:J Asphalt Road
~ o
_.._ Fence
-+- Railspur C:::J Gravel Road/ Pad
- 25 50 75 Figure 3-38. WMA 6. (Facilities to be removed during Phase 1 Decommissioning include the Demineralizer Sludge Ponds, the Sewage Treatment Plant, the Equalization Tank and Basin, the south Waste Tank Farm Tra ining Platform , and the remaining slabs.)
Revision 2 3-125
WVDP PHASE 1 DECOMMISSIONING PLAN Figure 3-39. The Rail Spur. {The rail spur leads to the Fuel Receiving and Storage Facility.)
Figure 3-40. The New Cooling Tower. {The cool ing tower will be removed , except for its concrete basin, before Phase 1 decommissioning activities begin .)
Revision 2 3-126
WVDP PHASE 1 DECOMMISSIONING PLAN J \GIS\AtcMa ~ EJS\Ti ical Re 1~MIMA 7 mxdtO 8111/2008 .Rt.Jf N
A WMA8 Approximate Location of Fonner NOA Lagoon W MA7 NRC *Licensed Disposal Area (NOA)
WMA6 WMA 9 Legend c::J NOA Barrier Wall c::J Wa erbodies c:JWaste Management Areas - ***- Streams/ StonnwaterOrainageways CJ Building CJ Asphalt Road c:::J Conc1ele Foundation GJ Gravel Road/ Pad 50 0 50 100 150 200 Feet Fence
--+- Railspur
-..u -
10 0 I
10 20 30 40 Meters Figure 3-41. WMA 7. (The only facility to be removed during Phase 1 decommissioning is the NOA hardstand pad .)
Revision 2 3-127
WVDP PHASE 1 DECOMMISSIONING PLAN N
A Legend c::::J Was\11 Management Areas CJ Waterbodies CJ Bu ilding - -*- Stream.i Stormwaler Drainageways D Coricret11 Foundation D Asphalt Road 75 0 75 15-0 225 300 Feet
....._ Fence
-+- Ra il~ r CJ G rav el Road/ Pad 25
==0 -=- -
25 50 75 I
100 Mete Figure 3-42. WMA 9. (The Drum Cell will be removed during Phase 1 decommissioning, along with NOA Trench Soil Container Area and the Subcontractor Maintenance Area .)
Revision 2 3-128
l WVOP PHASE 1 DECOMMISSIONING PLAN N
VVMA2 A WMA7 WMA9 Legend c::J Waste Marnagement Areas FoJlller Lagoon C:J Bu ilding c::J Waterbodies CJ Concrete Foundation - *- Streams/ Stormwater Orainageways 120 0 120 240 360 480 Feet
- - Fcence CJ Asphalt Road .-=w I
-.+- Railspur CZJ Gravel Road/ Pad 25 0 25 SO 75 100 Meters Figure 3-43. WMA 10. (Facilities to be removed during Phase 1 decommissioning include the New Warehouse and the remaining slabs and pads.)
Revision 2 3-129
WVDP PHASE 1 DECO MMISSIONIN G PLAN N I NNW * *
- NNE NW
..,,:.. ....... . .rt NE
- * '*~**
- WNW
- *** "'C' i *
- ENE
- \
1
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- I f SW .T J
~ 'ii SE '
SSW r**
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- SSE ,..
s Figure 3-44. Population Around the WVDP by Compass Vector. (The dots represent residences. The stars show the nearest residences by compass vector.)
Revision 2 3-130
WVDP PHASE 1 DECOMMISSIONING PLAN N
t
~ Mixed Urban/Residential Mixed Forest Land i] Agriculrural Land
~ Water 0 Strip Mines
- Western New York Nuclear S:ervioe Center Souroe: Satelite Imagery 199 (WNYNSC) Not to Scale; For Information On!
Figure 3-45. Land Use in the Vicinity of the Center Revision 2 3-13 1
WVDP PHASE 1 DECOMMI SSIONING P LAN F'REOUENCY BY TIME O F OCCURRENCE - All EVENTS Tornado F Scale
- 0
- 0 1 Mld-3AM lAM*6AM 6AM*9AM 9AM*Noon Noon-3PM JPM-6PM 6PM-9PM 9PM* Mld
- 0 0
- 2 !* NUMBER OF OCCURRENCES
- 3 FREOUEllCV av MONTM - ALL INEllTS
- 4 FREQUENCY BY F SCALE - ALL EVENTS 40 311 15
' 0 0
0 F4 JAN Fell MAii API! MAY Jl,JN JUL AUG SEP OCT NOV OEC
[
- tlUMBER OF OCCURRENCE$ [
- NllMBER OF OCCURRENCES Figure 3-46. Tornado Events in Western New York (1950 - 2002) (From National Weath er Service , Buffa lo)
Revision 2 3-1 32
WVDP P HASE 1 DECOMMISSIONIN G PLAN
.... *f**
- '4 l'R ovet..C:'f B't TIM! *Lt e\;-@tns I
- 00 100 Thunderstorm Wind Speed Unknown .
- ..
- Less than 55 kts 55
- 64 kts
- 65. 74 !<ts tMO*l-' l*~* ... ..
~
- A. * **~
- 75 kts or Greater
- f'P'rttiotr r,t Ouuitwicn f'REOUENC~ BY MOtHH All EVElllS FR(O<JEN<: Y av W\CoNITUOE (E\IENTS WITH MEASURED QR ESTIMr.TEO SPEED*
450 160 400 -
350 -
300 .*
'.'00
_..]
150 100 50 0 ~
JAl'I FEe MAR APR MAY JUii JUL AUG SEP OCT NOV DEC I* NumD11 or occun*ocu Figure 3-47. Thunderst orm Wind Events in Western New York (1950 - 2002) (From National Weath er Service, Buffalo)
Revision 2 3-133
WVDP PHASE 1 DECOMMISSIONING PLAN Hail Siz.e 0.76"
- 0.99" 1.00" - 1.99" 2.00" - 2.99"
- 3.00" . 4 .00" I JI * .., ,
rRfOUEUCYOY l\IONlH* ~Llfvt:NT!l n
10
&6 50 fO 30
- c
....I 10 0 -
.L JAii ~~"
""'" Ml AA.
tA:in'lbet Of 0caJ lft f1 CU 4uG !r.- oer NOV O!C Figure 3-48. Hail Events in Western New York (1950 - 2002) (From National Weather Service, Buffalo)
Revision 2 3-134
WVDP PHASE 1 DECOMMISSIONING PLAN N
2.72 w
4 .15 E
2.78 2.71 4.11 s
. 4.24 3 .66 Figure 3-49. Wind Rose Diagram. (1991 - 2003 average head-wind direction and average wind speed in m/s)
- Revision 2 3-135
WVDP PHASE 1 DECOMMISSIONING PLAN FREQUENCY OF OCCURENCE OF CEILINGS LESS THAN 3.000 FEET ANDIOR VISIBILITY LESS THAN 3 Mil.ES AT BUFFALO, NY ANO NIAGARA FALLS INTERNATIONAL AIRPORT 100 90 80 70 l 60 ffi 0
50
.a:.
w .ti) a.
30 20 10 0
~ FEB MAR APA MAY JUN JUL AUG SEP ocr NOV DEC ANNUAL AVG LEGEND:
- Buffalo 0 Niagara Falls Figure 3-50. Cloud Ceiling Information (From reference 3-11)
Revision 2 3-136
WVDP PHASE 1 DECOMMISSIONING PLAN 83' at* 75* 74*
~ I I
25 0 25 Physiographic Prwinoe 6oun<lary source: WJNS 1993a. Scale In Moles Figure 3-51 . Regional Physiographic Map Revision 2 3-137
WVDP PHASE 1 DECOMMISS ION ING PLAN Surficial Sand and Gravel Unit (3-4 1')
Weathered Lavery Till (3-1 6')
Lavery Till Sand lQ) ---
0 1! Unweathered Lavery Till (3-130')
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c
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- J Q) 0 cQ) Fi ne Sand & Silt 0
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- a; Intervening Silty Clay "iii a: 8. Sandy Gravel Outwash Deposits
~
]
~ Kent Till (Approx. 50')
!I Unweathered Till j 2l "& ?(capped by coarse 1recessional deposits, not well characterised locally, t hickness o -~
unknown) c >- 1,1111111 c
(0
~
-0 I I I I I 11I 1 1I 1 1I 1 1I 1 Slightly Calcareous G ray Siltstooes QI al c
1 1 1 1 1 1 1 1 1 and Shales (Weathered and 0 al 1 1 1 1 1 Fractured at Top)
() 1 1 1 1 I I I I I Figure 3-52. Bedrock and Glacial Stratigraphy of the WVDP Revision 2 3-138
WVDP PHASE 1 DECOMMISSIONING PLAN EXPLANATION :
G:i GRAVEL ANO SANO *Alluvial fans an:f floodplains
~ deposited before Incision by~ day slreams
[II TILL
- Predominantty day and sit. incorporating disoonti'ILIOUS delOlmed lragmerts of layered secfmens fjJ GRAVEL AND (OR) SAND* Locally underlaii by fine sand 10sit dellalc and ~n deposits m SILTANDCLAY 1 RHYTHMIClAYERS
- Scattered pebbles and msorted sed'merts dropped from ftoaling ioe
~ TIU. - Similar to Unit 5 frJj LAYERED, LOCALLY DISTURBED SILT AND CLAY
- Sin"llar lo lri 9
[E) Till - More sandy and slorry !hall mils 5 and 10 CONTACT BETWEEN GEOLOGIC UNITS
- Dashed Where inlerrad ApproJCima'te boundary of the Proj&c! Premises Location of Geologic Cross Sections in Figures 3*6 and 3*7 42"26'30" -
'°~ 1000 2000 I
Figure 3-53. Surface Geology of the Project Premises and the SDA Revision 2 3-139
WVDP PHASE 1 DECOMMIS SI ONING PLAN
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... ... ~ '_1 AOcHESTER
~
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Sl'lt*t 0//1 SU I JO&NTS IN tlrOV"IDOAl OUTCROP!
AHll( 'CS Figure 3-54. Fold and Selected Joint Trends in the Appalachian Plateau of Western and Central New York Revision 2 3-140
WVDP PHASE 1 DECOMMISSIONING PLAN I
LAKE ONT ARID
-* - ** - - ** - * - ** - * - *. - I N
\ -
litl'llt ar SOSHlt 000 4 l*IO
- 18 Figure 3-55. Seismo-Tectonic Map of Western New York Showing Selected Regional Geologic Structures Revision 2 3-141 .
WVDP PHASE 1 DECOMMISSIONING PLAN 0 100 I I I I I I Kilometers eoo 790 76° 74° 72° Figure 3-56. Major Northwest Trending Lineaments in New York and Pennsylvania (PW - Pittsburgh-Washington Lineament, T-MU - Tyrone-Mt. Union Lineament, L-A - Lawrenceville-Attica Lineament, F - F Lineament)
Revision 2 3-142
WVDP PHASE 1 DECOMMISSIONING PLAN 0 ... ..
- ' Stahl #1"
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., 0 1 ~ 3 4 5 Figure 3-57. Location of Seismic Lines WVN1 and BER 83-2A Revision 2 3-143
WVDP PHASE 1 D ECOMMISSIONING PLAN
- - - - - - Total Mean Hazard 5th and 95th Percentiles 15th and 85th Percentiles 50th Percentile
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- 0. 16 0 18 0.2 0.22 02' 026 o.za 0.3 100.000 Peak Ground Acceleration (g)
Figure 3-58. Seismic Hazard Curves for Peak Horizontal Acceleration Revi sion 2 3-144
WVDP P HAS E 1 DECOMM ISSI ONING PLAN Total Mean Hazard 5th and 95th Percentiles 15th and 85th Percentiles 50th Percentile
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Figure 3-59. Seismic Hazard Curves for 1.0 Second Horizontal Spectral Acceleration Revision 2 3-145
WVDP PHASE 1 D ECOMMISSIONING PLAN
- - - - - - Total Mean Hazard
- - - - - Clarendon-Linden Fault Zone
- Southern Great Lakes Zone (SGl )
Gridded Seismicity
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Figure 3-60. Seismic Source Contributions to Mean Peak Horizontal Acceleration Hazard Revi sion 2 3-146
WVOP PHASE 1 DECOMM ISSIONING PLAN c
Canada Lake Erie Cattaraugus Creek - --=""'-...._
Dra.inage Basin Explanation :
Lavery L J Kent
~ Olean D*!.: Defiance .. Lake Escarpment 05 0 05 1 1 5 Miles Figure 3-61. Buttermilk Creek Drainage Basin Revision 2 3-147
l I I
WVDP PHASE 1 DECOMMISSIONING PLAN J \ IS\At(;:M.a I
Watert:>odies
$ Mu11ilu1 i11g luc;olioO 1st-Quarter 2008 t=*.:i Approximate Extent of Sand & Gravel Unrt Ground.Yater Elevation Contours in 1435.53 Groundwater Elevation the Sand & Gravel Thick-Bedded Unit Jnfe<red Zolll!S or Seepage
- - Elevalion Conlour Line west valley Oernonstranon Project Contour tnlervaf: 2 feet West valley, New York Map Based on 1996 flY-Over Suvey Water Levels Were Measured on November 28. 2007 Water Elevations in Feet Above Mean Sea level (M_$ _L)
Figure 3-62. Groundwater Elevation Contours of the Sand and Gravel Unit, First Quarter 2008 Revision 2 3-148
WVDP PHASE 1 DECOMMISSIONING PLAN
,,. p n A
1104A 137035 909 136597
/
1103~~. /
1109A 1365.7 \ 17 ~~~
I 1-7 ~MW-I 1366~
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~: 137404 SMW-6 sr '2 110ZA 1379 60 1313n 9$-91 L~end
-$ Monllc,..19 location
$ MooUor'f1!) Location Moni1<>1ed by NYSEROA 1st-Quarter 2008
$ CutT"'11~ Oly Montte<.ig Localoon Mon~Ofed by NYSERDA W.te1 E lovalion Contour i...e Grounc:t.\later Elevation Contours 1435.53 GrO\Jndweler Elevation in the Weatl1ered Lavery Tlll Localion oflhe NOil. lnle1oeplor Trench \o'\Rst Valley Demonstration Project N...~rllri~tio~~~~~~~'Y..~ 5 1"0< l.l'okst Valley, New York Map S.>ed on 1996 Flv-Om SlllV"'i L- bv.m M..sun*d on - :4 2001 NYSERO.-Wllw l ..,.tl..._. M* tUNG on ~r 18 2007
'¥VM.er~ tnf'tetAt>cweMeanSe11L......i M: S l )
Figure 3-63. Groundwater Elevation Contours of the Weathered Lavery Till, First Quarter 2008 Revision 2 3-149
WVDP PHASE 1 DECOMMISSIONING PLAN N
A Legend
-$ Monttoring Location Elevation Contour Line 1st-Quarter 2008 1435. 53 Groundwater Ele\'ation Groundwater Elevation Contours c.:-:J Approximate Extent of Lavery Tilt-Sand Unit in the Lavery Till-Sand CoriolX lntervat 2 reet West. Valley Demonstration Project Map Based on 1996 Fly-Over Survey VI/est Valley, NeW York Wa er Levels Were Measured on November 28, '2007 Wiler Elevations In N!et Above Mean Sea level {M.S.
Figure 3-64. Groundwater Elevation Contours of the Lavery Till Sand, First Quarter 2008 Revision 2 3-150
WVDP PHASE 1 DECOMMISSIONING PLAN
- p N
A
\
\
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\
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I
\
\
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Legend
-$ Monltorll1!1 Locat10t1 flevalion Contour Line 1st-Quarter 2008 Groundwater Elevation Contours Estimated Extent of the Kent Recessional Sequeoce in the Kent Recessional Sequence 1435.53 Groundwater Elevation West Valley Demonstration Project Cortoi.r Interval: 10 feet Map Based on 1996 Fly-Over Survey West Vaney, New York
\Nate r Levels Were Measured on November 28, 2007
'Mlle! Elevations In Feet Above Mean Sea Level (M.S.L)
Figure 3-65. Groundwater Elevation Contours of the Kent Recessional Sequence, First Quarter 2008 Revision 2 3-151
WVDP PHASE 1 DECOMMISSIONING PLAN Cesium Cesium
- a 0 0
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Vl 0
0 l()
- 8 -
l()
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ro
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Un\'\athered Theoretical Quantiles Geohydrological Unit Figure 3-66. Vertical Distribution of Cesium Kd in the Weathered and Unweathered Tills (WVNSCO 1993a) l() l()
c0
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-1.5 -0.5 0.5 1.0 1.5 Weathered Unweathered Figure 3-67. Vertical Distribution of Iodine Kd in the Weathered and Unweathered Tills (WVNSCO 1993a)
Revi sion 2 3-1 52
WVDP PHASE 1 DECOMMISSIONING PLAN Strontium Strontium 0 0 0
N
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a a
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Revision 2 3-153
WVDP PHASE 1 DECOMMISSIONING PLAN BUFFALO
- .:. . **....:t....*...:*......
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SALAMANCA Figure 3-69. Locations of Natural Gas and Oil Wells in Western New York Revision 2 3-154
WVDP PHASE 1 DECOMMISSIONING PLAN
--.----'_"'._'.- - - . i7\ \.
\
\ ':/7"'
\_'Ml Gas Well (Typical)
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~ Inactive Gas Well (Typical) 209e7 20897
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21769
/ , I
-¢- / / 21115 }-..-/
2'c~oJ V I II ,<:--~ \
l ): _/\ \
,...,- \ @ ' ~
Figure 3-70. Locations of Natural Gas and Oil Wells in the Vicinity of the WVDP Revision 2 3-155
This page is intentionally blank.
WVDP PHASE 1 DECOMMISSIONING PLAN 4.0 RADIOLOGICAL STATUS OF FACILITY PURPOSE OF THIS SECTION The purpose of this section and the related Appendix B is to provide summary information on the radiological status of the facilities and environmental media within the scope of the plan . This information is intended to enable readers to understand the types, levels, and general extent of radioactive contamination in the WVDP facilities and in soil, sediment, groundwater, and surface water on the project premises .
INFORMATION IN THIS SECTION This section focuses mainly on facilities and areas within the scope of the plan.
- Section 4.1.1 discusses sources of available radiological data , background radioactivity, the origin of site radioactivity, and the mode of contamination in facilities .
- Section 4.1.2 identifies facilities impacted by radioactivity.
- Section 4.1.3 identifies facilities not impacted by radioactivity as of 2009.
- Section 4.1.4 provides information on radionuclide distributions in facilities .
- Section 4.1.5 summarizes the radiological status of the facilities of interest.
- Section 4.2 addresses the radiological status of surface soil, sediment, sub-surface soil , surface water, and groundwater and identifies impacted and non-impacted areas of the project premises. It also provides data on environmental radiation levels.
Additional radiological characterization will be performed where appropriate as described in Section 7 and Section 9.
RELATIONSHIP TO OTHER PLAN SECTIONS To put into perspective the information in this section, one must consider:
- The information in Section 1 on the project background and those facilities and areas within the scope of the plan;
- The information in Section 2 on site history,
- processes, previous decommissioning activities, and spills; and
- The facility descriptions, photographs, and illustrations in Section 3.
The radiological status information in this section provides the context for information provided in later sections, such as the dose modeling described in Section 5, the decommissioning activities in Section 7, and facility radiation surveys in Section 9.
Revision 2 4-1
WVDP PHASE 1 DECOMMISSIONING PLAN 4.1 Radiological Status of Facilities, Systems, and Equipment This section summarizes existing data on radiological conditions in WVDP facilities, systems, and equipment. To fully define the radiological status of facilities and equipment within the scope of this plan, additional characterization will be performed in connection with Phase 1 decommissioning activities as described in Sections 7 and 9.
4.1.1 Sources of Available Data Radiological data on facilities, systems, and equipment are available from the Facility Characterization Project, which focused on the Process Building and the Vitrification Facility, and from several other sources .
Facility Characterization Project The Facility Characterization Project, as described in the Characterization Management Plan for the Facility Characterization Project (Michalczak 2004a) , produced conservative estimates of radionuclide inventories in various areas of the Process Building and in the 01 -
14 Building and the Vitrification Facility . These estimates are documented in a series of 1
radioisotope inventory reports issued between 2002 and 2005 .
The Facility Characterization Project focused on the following radionuclides of interest:
Am-241 Cs-137 Pu-239 Tc-99 U-235 C-14 1-129 Pu-240 U-232 U-238 Cm -243 Np-237 Pu-241 U-233 Cm-244 Pu-238 Sr-90 U-234 Sixteen of these radionuclides (all except Sr-90 and Cs-137) were determined to be of interest because of their impacts in dose analyses associated with long-term performance assessment of the partially remediated site (Michalczak 2004a). Strontium-90 and Cs-137 were included because they are among the dominant radionuclides in site radioactive contamination and because they could have significant dose impacts in the near term. 2 The process used to compile total activity estimates was inherently conservative for several reasons. These reasons include (1) assuming in dose rate-to-activity modeling that all measured gamma radiation was due to a single surrogate radionuclide (Cs-137 or Am-241 ), even though other gamma-emitting radionuclides may have also been present, and (2) use of the most conservative rad ionuclide distribution data for estimating scaling factors relating amounts of other radionuclides to Cs-137 in cases where mu ltiple sets of radionuclide distribution data were available (Michalczak 2004a) .
1 The Facility Characterization Project focused on source term estimates beca use when it was initiated the decommissioning approach was expected to entail in-place closure of a portion of the upper structure of the Process Building, as well as the underground portions of the structure and the Vitrification Facility.
2 Additional information about selection of the radionuclides of primary interest for the Facility Characteriza-tion Project and in developing DCGLs for soil and sediment contamination appears in Section 5.2 .
Revision 2 4-2
WVDP PHAS E 1 DECOMMISSIONING PLAN In addition to the source term estimates, the radioisotope inventory reports contain information on radiological history, radionuclide distributions, contamination levels, and radiation levels.
Characterization of the Underground Waste Storage Tanks The four waste storage tanks have undergone detailed characterization. Data collection and analysis for Tanks 8D-1 and 8D -2 were performed in accordance with an approved data collection and analysis plan (Fazio 2001 ). The characterization results appear in three radioisotope inventory reports (Fazio 2002a , Fazio 2002b, and Fazio 2004c), which explailil the characterization methodology . These reports were provided to NRC in connection with preparation of the Decommissioning EIS.
In response to comments on the radioisotope inventory reports from NRC and other agencies, DOE prepared a supplemental report (WVNSCO and Gemini 2005) to clarify information on radionuclides of significance, address uncertainty in the inventory estimates, and provide additional information on the technical basis for scaling factors and on the mobile inventory estimate for Tank 8D-4 .
Other Facility Residual Radioactivity Estimates In 2008, the site contractor, West Valley Environmental Services (WVES), developed additional estimates for residual radioactivity in the Process Building, the Vitrification Facility, and underground waste storage Tanks 8D-3 and 8D-4 in the interim end state, i.e ..
at the beginning of the Phase 1 decommissioning activities (WVES 2008a, WVES 2008b, and WVES 2008c, respectively). These estimates utilized the previous characterization results combined with projections based on additional decontamination to be performed in certain areas in connection with work to achieve the interim end state .
Analytical Data The results of analyses of numerous liquid and solid samples performed by both onsite and offsite laboratories are available. These data, most of which are summarized in the radioisotope inventory reports, have been used to define radionuclide distributions in various areas of the Process Building and in the Vitrification Facility, the underground waste tanks, and other WVDP areas.
Routine Radiological Survey Data for Facilities Routine radiological status surveys are performed in WVDP facilities in support of the WVDP radiation protection program. Data from these surveys, which typically include general area gamma radiation levels and removable beta contamination levels, reflect the current radiological status in accessible areas of most WVDP facilities .
Scoping Data Available radiological data on facilities, systems, and equipment are generally considered to be scoping data, with the exception of data on the underground waste tanks, which have been appropriately characterized . As defined in the Multi-Agency Radiation Revision 2 4-3
WVOP PHASE 1 DECOMMISSIONING PLAN Survey and Site Investigation Manual (MARSSIM) (NRC 2000), scoping survey data identify radionuclide contaminants, relative radionuclide ratios, general levels, and the extent of contamination, yet may not comprise definitive characterization data . In some areas, available data are insufficient to meet the definition of scoping data , especially in cases where radionuclide ratios are not available or where the extent of contamination is not defined . (As noted previously, additional characterization will be performed in connection with Phase 1 decommissioning activities as described in Sections 7 and 9.)
Background Radioactivity Limited data are available on background radioactivity in structures, although there are data from areas with a low potential for contamination. For example, typical routine surveys show gamma radiation levels <0.1 mR/h in the Solvent Storage Terrace and Acid Handling Area of the Process Building (Michalczak 2004b) and measurements taken with sodium-iodide detectors recorded in µRlh are available in some low-potential areas. During the characterization surveys of structures described in Section 9.4. 5, sufficient data will be acquired to establish background levels in structures within the scope of the Phase 1 decommissioning activities.
Origin of Site Radioactivity Radioactivity associated with the project premises originated from irradiated nuclear fuel reprocessed in the Process Building . Analytical data on radioactivity in the fuel are available as described below. With the exception of one batch of thorium-uranium fuel, all fuel reprocessed was uranium based, as noted in Section 2.
Information on how the facilities became contaminated is contained in Section 2.
Mode of Contamination in Facilities In many cases, radioactive contamination associated with facilities is located only on facility surfaces, and does not penetrate into the surfaces, and inside contaminated systems and equipment. In some cases contamination is also located on the outside of systems and equipment.
Exceptions primarily involve contamination of Process Building facility surfaces in depth from spills of radioactive acid on painted concrete surfaces and where radioactive water stood in the fuel pools. This conclusion is generally based on radiation level measurements on decontaminated surfaces that have minimal removable contamination . Quantitative information on the depth of penetration is available only in a single case: one sample from a wall of the Chemical Process Cell that showed contamination had penetrated approximately two inches into the concrete (URS 2001 ).
Data Provided in this Section Section 4.1 provides estimates of residual radioactivity for the Process Building and the Vitrification Facility, which are within the scope of this plan, and for information and perspective, the underground waste storage tanks , and the N RC-Licensed Disposal Area (NOA). Data on radiation levels in representative areas of the Process Building, in the Revision 2 4-4
WVDP PHASE 1 DECOMMISSIONING PLAN Vitrification Facility, and in other areas are provided . Residual radioactivity in other areas is also discussed .
4.1.2 Impacted Facilities The following facilities where licensed activities and/or WVDP activities have taken place are known or suspected to contain residual radioactive material in excess of background levels. Figures 4-1 shows the location of WMAs on the project premises and Figures 4-2, 4-3, 4-4, and 4-5 show the locations of the fa cilities of interest. This list does not incl ude facil iti es existing in 2009 that wi ll be removed before the Phase 1 decommissioning activities begin, which are addressed in Section 2.2 .2. However, it does include for information and perspective some facilities that are not within the scope of Phase 1 of the decommissioning.
WMA 1, Process Building and Vitrification Facility Area
- Process Building
- Utility Room and Utility Room Expansion
- Plant Office Building
- 01-14 Building
- Load-I n/Load-Out Facility
- Vitrification Facility
- Vitrification off-gas trench lines
- Underground wastewater Tanks 35104, 70-13 , and 150-6
- Underground lines WMA 2, Low-Level Waste Treatment Facility Area
- LLW2 Building
- Old Interceptor
- New Interceptors (2)
- Neutralization Pit
- Lagoon 1 (deactivated)
- Lagoon 2
- Lagoon 3
- Lagoon 4
- Lagoon 5
- Solvent Dike Revision 2 4-5
WV D P PHASE 1 DECOMMISSIONING PLAN
- Underground wastewater lines 3
- French drain
- Maintenance Shop leach field
- North Plateau Groundwater Pump and Treat Facility (not in plan scope)
- Pilot permeable treatment wall (not in plan scope)
- Full-scale permeable treatment wall (to be in stalled , not in pl an scope)
W MA 3, Waste Tank Farm Area 4
- Underground waste Tanks 8D-3 and 8D -4 and their common vault 3
- Con -Ed Building
- Equipment Shelter and Condensers
- HLW Transfer Trench piping
- Permanent Ventilation System Building (not in plan scope)
- Supernatant Treatment System Support Building (not in plan scope)
- Underground lines (not in plan scope)
WMA 4, Construction and Demolition Debris Landfill Area
- Construction and Demolition Debris Landfill (not in plan scope)
WMA 5, Waste Storage Area
- Lag Storage Area 4 and Shipping Depot
- Remote Handled Waste Facility WMA 6, Central Project Premises
- Demineralizer sludge ponds (2)
- Cooling Tower basin
- Rail Spur (because of nearby soil contamination, not within plan scope)
WMA 7, NOA and Associated Facilities
- Entire area (only the hardstand is within plan scope)
WMA 9, Radwaste Treatment System Drum Cell Area
- Radwa ste Treatment System Drum Cell 3
Only those lines within planned excavations to remove facil ities are within plan scope.
4 Only th e tank mobilization and transfer pumps and th eir support structures are within th e scope of this plan.
Revision 2 4-6
WVDP PHAS E 1 D ECOMMISSIONING PLAN
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-..4--- WIOP Rthpw Figure 4-1 . Location of WMAs on the Project Premises Revision 2 4-7
WVDP PHASE 1 DECOMMISSIONING PLAN N
A "t Impacted Facility 0 Non-Impacted Facility Legood c:::J wn:e Monaoement,.,,eos o Wa:*rboctu
[::J ~ ~ - - 9:rottwnslSl<<JJMa!tf Ct31rto'¥:'**Y'S \
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O 10 50 20 100 30 150 40 Meters 200Feet
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- ::;:;:;;;;;;:J Figure 4-2. Impacted and Non-Impacted Facilities in WMA 1 Revision 2 4-8
WVDP PHASE 1 DECOMMISSIONING PLAN WMA2 6f Impacted Facility D Non-Impacted Facility Cl \Y9~* M3""emtrlAIHt Fortner Lago.at r:::J WJOP a..
0 WltltlfbodH E j Conct<le c...,-
75 0 75 150 225 300 Feet
- - SratM/Slc:rrnvt.r*rCh.l\IQe'Na\'I r:::J Mp'llllflooO I
~ Gl'llivtl ::laad/~ 25 0 50 75 100 Meiers Figure 4-3. Impacted and Non-Impacted Facilities in WMA 2 Revision 2 4-9
WVOP PHASE 1 DECOMMISSIONING PLAN N
A LEGEND
~ =Impacted Facility PVS = Permanent Ventilation System STS = Supernatant Treatment System c:::::J waste Management Areas Waterbodics c:J WI/DP Bu lding - ---- Strea~ Storrrr.w1er Drainageways
(~ "'~ J Concrete Foundation c:=J Asphalt Road
- - VWDP Fence f:';W9Gravel Road/ Pad
-+-- WI/DP Railspur All facilities in WMA 3 have been impacted by radioactivity.
Figure 4-4. Impacted Facilities in WMA 3 Revision 2 4-10
WVDP PHASE 1 D ECOMMISSIONING PLAN N
A quallzatlon Basin
-r Impacted Facility D Non-Impacted Facility WMA7 WMA10 Figure 4-5 . Impacted and Non-Impacted Facilities in WMA 6 Revision 2 4- 11
WVDP PHASE 1 DECOMMISSIONING PLAN 4.1.3 Non-Impacted Facilities The following structures and locations* have not been impacted by radioactivity associated with licensed activities or WVDP activities as of 2009, based on process history, the results of routine radiological surveys. and the results of the WVDP environmental monitoring program (WVES and URS 2009). These facilities are shown in Figures 4-1 , 4-2.
or 4-5.
WMA 1, Process Building Area
- Fire Pump House
- Water Storage Tank
- Electrical Substation WMA 6, Central Project Premises
- South Waste Tank Farm Test Tower
- Equalization Basin
- Equalization Tank WMA 10, Support and Services Area
- New Warehouse
- Meteorological Tower (not within plan scope)
- Security Gatehouse and Fences (not within plan scope)
Even though the Sewage Treatment Plant is considered not to have been impacted by radioactivity associated with licensed activities or the WVDP as of 2009, the excavation dug for its removal will be considered in Phase 1 final status surveys because of the potential buildup of naturally-occurring radioactivity in sewage sludge, as explained in Section 7.
Some WMAs also contain concrete floor slabs and foundations and gravel pads that will be removed during Phase 1. Some of the concrete slabs have been impacted by radioactivity as explained in Section 2 and may contain low levels of residual radioactivity .
Note that conditions in the non-impacted facilities are subject to change . DOE or its decommissioning contractor will reevaluate the conclusion that these facilities have not been impacted before decommissioning activities begin .
4.1.4 Radionuclide Distributions Owing to the nature of spent fuel separation and purification processes, radionuclide distributions vary between different areas of the Process Building and in other facilities of interest such as the Vitrification Facility depending on the point in the reprocessing cycle where the contamination originated . Other factors discussed below also influenced radionuclide distributions inside the Process Building and the Vitrification Facility.
Revision 2 4-12
WVDP PHAS E 1 DECOMMISSIONING PLAN During the Facility Characterization Project, available analytical data and data from samples obtained and analyzed during thi s project were utilized to establish bounding radionuclide scaling factors. These sca ling factors , which relate the concentrations of other radionuclides of interest to the concentration of Cs-137 or Am-241 , were chosen to ensure that concentrations of radionuclides important to the dose evaluation were not underestimated 5 .
The two principal radionuclide distributions that were available before the beginning of the Facility Characterization Project are known as the spent fuel distribution and the Batch 10 distribution . These distributions and their application to porti ons of site facilities are discussed below.
Spent Fuel Distribution Informati on on the radionuclide distribution associated with spent nuclear fuel ha s been derived primarily from the results of modeling of fuel processed by Nuclear Fuel Services (NF S) that was performed by Pacific Northwest National Laboratory using the ORIGEN2 computer code (Jenquin, et al. 1992) . These data were used for all radionuclides of interest in spent fu el except U-235 and U-238 , which were derived from NFS record s for recovered and unaccounted for losses of uranium, and U-232, U-233 , U-234, and U-236, wh ich were established based on analytical results showing the U-232 to U-235/236 ratio from samples collected in the Acid Recovery Pump Room of the Process Building . The resulting scaling factors relating concentrations of other radionuclides of interest to the concentration of Cs-137 were determined to be conservative (Mahoney 2002) . These scaling factors are shown in Table 4-1 .
1 Table 4-1. Scaling Factors for Spent Fuel Reprocessed <>
Nuclide Ratio<2> Nuclide Ratio<2> Nuclide Ratio<2>
Am-241 8.58E -02 Np-237 4.5E-06 U-232 6.9E-01 C-14 1.3E-04 Pu-238 1.69E-02 U-233 1.40E+OO Cm -242 2.0E-04 Pu-239 2.84E-02 U-234 9.0E-02 Cm-243 5.9E -05 Pu -240 1.48E-02 U-235 1.5 E-06 Cm-244 1.52E-03 Pu-241 9.10E-01 U-236 1.39E-01 1-129 6.3E -0 7 Tc-99 2.7E -04 U-238 2.6E-05 Notes: (1) From Mahoney 2002, Tables 1 and 2, reference date January 1, 1993.
(2) All are scaled to Cs-137 , except for U-232, U-233, U-234, and U-236, which are scaled to U-238 . Sr-90 does not appear in the tables of calculated scaling factors in Mahoney, 2002. The Sr-90 to Cs-137 ratio was determined to be 9.SE-01 (WVNSCO 1989).
- Note that in compiling estimates during the Facility Characterization Project, the reference date was adjusted to September 30, 2004 and the values for U-232, U-233, U-234, and U-236 were scaled to Cs-137 rather than U-238.
5 Where multiple data sets were available, tlie highest values among radionuclide ratios from the different data sets were selected for each radionuclide for conservati sm (Michalczak 2004a) .
Revision 2 4-13
WVDP PHASE 1 DECOMMISSIONING PLAN l lhe method used to est ablish l'he ratios for U-232 , U-233 , llJ-234 and U- 236, which involved use of a111alytical data from a sample collected in the Aoid Recovery Pump Room (Maho111e_y 2002) , ma_y have somewhat underestimated the amounts of these radionuolides with respeot to the amount of U-238 in areas of the Prooess Building further downstream.
However, as the uranium isotopes are only a small fractiion of the alpha-emitting radionuolides in thle residual radioa aLivity {Am-241 a111d Pu- 239 are - 1000 times greater).
the impact of underestimating uranium i111ventor_y (U -232, U-233 , U-234, and U-236} i s not significant.
Batch 10 HLW Distribution The vitrification Batch 10 distribution was used to establish bounding scaling factors rel ated to Cs-137 for HLW . The Batch 10 sample analyzed was obtained from the first HLW transfer from underground waste Tank 80 -2 to the Vitrification Facility in 1996. It was representative of the waste in its most concentrated form wh en the highest ratios of alpha-emitting tra nsuranic radionuclides to Cs-137 were present. Later batches contain ed relatively higher concentrations of Cs-137 (and lower ratios of alpha-emitting transuranics to Cs- 137) because Cs -137 captured in Supernatant Treatment Sy stem zeolite resin was returned to Tank 80-2 for subsequent transfer to the Vitrification Facility.
The Hatch 10 sampl e was analyzed in May 1997 by the Radiological Processing Laboratory at Pacific Northwest National Laboratory. The analysis results are shown in Table 4-2.
Table 4-2. Batch 10 Sample Datal1J Nuclide µCi/g Nuclide µCi/g Nuclide µCi/g Am-241 3.21 E+01 Np-237 2.00E-02 Tc-99 8.45E-02 C-14 4.90E-04 Pu -238 3.96E+OO U-232 NA(2J Cm-243 2.58E-01 Pu-239 1.09E+OO U-233 3.60E-03 Cm-244 6.72E+OO Pu-240 7.70E-01 U-234 1.30E-03 Cs-137 2.85E+03 Pu-241 3.43E+01 U-235 3.80E-05 1-129 3.90E -07 Sr-90 2.75E+03 U-238 3.40E-04 Notes: (1) From Pacific Northwest National Laboratory results corrected for decay and ingrowth to May 15, 1997, included in Michalczak 2003b. *
(2) Not available. No analysis was perform ed for U-232.
Process Building Distributions During the Facility Characterization Project. the spent fu el distribution. the Batch 10 distribution. and area -specific radionuclides distributions were used in conjunction with sa mple analytical data to determine the appropri ate radionuclide activity inventory for various representative areas of the Process Building . For example, in the calculation of the bounding radionuclide activity inventory of the Product Purification Cell, where uranium concentrations would be expected .to be highest. the radionuclide distribution was determined from six samples obtained from the floor and walls of this cell , rather than using Revision 2 4-14
WVDP PHASE 1 DECOMMISSIONING PLAN
~he spent 1fuel distribution, which would be lil1ore representative of radionuolides in earlier steps of the process stream (Choroser 2003).
Contamination in most areas of the building resulted primarily from spills and leaks of materials in the reprocessing feed and waste process streams . This feed and waste contamination is associated with reactor fuel before fission products have been separated or with the separated fission products. Until the point where the fuel was dissolved in the Chemical Process Cell, radionuclide ratios remained characteristic of the feed and waste process streams, typified by the spe111t fuel distribution in Table 4-1 .
Downstream of the dissolution process that took pl ace in the Chemical Process Cell, radionuclide ratios began to change in the extraction cells, where the dissolved fuel underwent . a solvent extraction process that separated uranium and plutonium from the fission products . The uranium and plutonium products achieved their purest forms in the Product Purification Cell.
Contamination in other areas of the building came primarily from spills or leaks of the reprocessed products . These other areas are the Product Purification Cell, the Lower Warm Ai sle, the Product Packaging and Handling Area , and the Extraction Sample Aisle .
There are substantial variations among distributions in different areas. One particular spill during reprocessing that affected radionuclide distributions in several areas was the release of highly radioacti ve nitric acid from an acid recovery line in the southwest corner of the building, as described in Section 2.
The dominant radionuclides in the Process Building contamination are typically Cs-137, Pu-241 , Sr-90, Am-241, and Pu-238 . The relative fractions of dominant radionuclides in the two basic distributions can be calculated based on the geometric means of the distributions in the various Process Building areas. Table 4-3 shows the results of these calculations .
However, there are significant variations from these relative fractions in the different areas for which data were compiled .
Table 4-3. Relative Fractions of Process Building Dominant RadionuclidesP>
Relative Fractions of Dominant Radionuclides in Feed and Waste Contamination Radionuclide Pu-241 Cs-137 Sr-90 Am-241 Pu-238 Fraction 0.404 0.281 0.216 0.065 0.035 Relative Fractions of Dominant Radionuclides in Product Contamination Radionuclide Pu-241 Am-241 Pu-238 Pu-239 Pu-240 Fraction 0.754 0.133 0.045 0.039 0.029 NOTE : (1) Based on geometric means of radionuclides in the differently impacted areas using data from th e Fa ci lity Characterization Proj ect radioisotope inventory reports. These were the ratios on September 30, 2004, the reference date for th e data used. There are significant variations from these relative fractions in the different areas for which data were compiled.
Revision 2 4-15
WVDP PHASE 1 DECOMMISSIONING PLAN The information on radionuclide distributions for different Process Building areas found in the radioisotope inventory reports produced by the Facility Characterization Project will be used for planning decommissioning activities in the building and for waste management purposes .
Vitrification Facility Distributions The other facility with a signifiicant amount of residual radioactivity is the Vitrifica~i on Facility. The relative fractions of the dominant radionuclides in the Vitrification Facility are shown in Table 4-4.
Table 4-4. Relative Fractions of Vitrification Facility Dominant Radionuclidesl1J Radionuclide Cs-137 Sr-90 Am-241 Pu-241 Cm-244 Fraction 0.506 0.482 0.007 0.005 0.001 NOTE: (1) Based on data in Radioisotope Inventory Report RIR- 403-010 (Lachapelle 2003) as of December 31 ,
2006 as given in WV ES 200 8b.
4.1.5 Radiological Status of Facilities Most of the residual radioactivity in facilities within the scope of this plan resides in two areas: the Process Building and the Vitrification Facility. Significant amounts of radioactivity are also located in Lagoon 1, Lagoon 2, the piping in the HLW transfer trench, the vitrification off-gas line that runs to the 01 -14 Building, and underground piping in the Process Building area.
Radioactivity in WMA 1, the Process Building The Facility Characterization Project provided residual inventory estimates for 33 different areas of the Process Building, including a group of "low ranking" areas. However, additional decontamination work is being accomplished in the Off-Gas Cell, the General Purpose Cell, and the Process Mechanical Cell.
Table 4-5 provides an estimate of the total amount of residual radioactivity that will be in the building when the interim end state is reached, that is, at the beginning of Phase 1 decommissioning activities. The estimates account for the expected effectiveness of the planned decontamination work, which will include removal of certain equipment and two decontamination cycles for the floors and walls of the General Purpose Cell, the Process Mechanical Cell, and the Off-Gas Cell (WVES 2008a) .
Table 4-5. Estimated Process Building Residual Activity at Start of Decommissioning(1l Nuclide Estimate (Ci) Nuclide Estimate (Ci) Nuclide Estimate (Ci)
Am-241 260 Np-237 0.57 Tc-99 4.9 2
C-14 13 Pu-238 200 U-232' l 0.75 2
Cm-243 0.27 Pu-239 63 U-233( l 0.41 2
Cm -244 6.3 Pu -240 47 U-234( l 0.19 Revision 2 4-16
WVDP P HASE 1 D ECOMMISSIONING PLAN Table 4-5. Estimated Process Building Residual Activity at Start of Decommissioning(i)
Nuclide Estimate (Ci) Nuclide Estimate (Ci) Nuclide Estimate (Ci)
- Cs- 137 2550 Pu-24 1 1100 U-235 0.03 1-129 0.63 Sr- 90 1900 U-238 0.09 (1) From WVES, 2008a , not including the amounts for "yard" (i.e., the three underground wastewater tanks) and the 01 -14 Building, with th e estimates rounded to two significant figures or the nearest integer. These estimates were corrected for decay and ingrowth to 2011 . They do not include activity associated with th e HLW ca nisters or approximately 11 O curies in embed ded piping in the Process Building (McNeil 2005a) .
(2) l1he estimated amounts of these radionuolides could be somewhat low due to the manner in whioh their scaling ratios to U-238 were Initially developed (Mahoney 2002). However, as the uranium isotopes are only a small fraotion of the alpha-emitting radionuclides in the residual radioaotivity (Am-241 and Pu-239 are - 1000 times greater), the impact of underestimating Uranium inventory (U-232, U-233, U-234, and U-236) is not significant Table 4-6 shows the total estimated residual radioactivity inventory in different areas of the Process Building as of 2004.
Table 4-6 . Estimated Total Activity in Representative Process Build ing Areas (i)
Area Curies Area Curies Ana lytical Decontamination Aisle <1 Ma in Plant Stack 88 Acid Recovery Cell(l) 60 Miniature Cell 9 Acid Recovery Pump Room 31 Off-Gas/Acid Recovery Aisle 40 Ana lytical Hot Cells 39 Off-Gas Blower Room 72 Bu ild ing Roof 1 Off-Gas Cell(l) 250 Chemical Crane Room 6 Process Mechanical Cell(l) 1000 Chemical Process Cell 130 Process Sample Cells, 1C Sample Station 6 Equipment Decontamination Rm 36 Product Purification Cell 43 Extraction Cell 1(l) 47 Sa mple Storage Cell 17 Extraction Cel l 2 2 Scrap Removal Room <1 Extraction Cell 3(l) 11 Southwest Stairwe ll 5 Fuel Receiving and Storage 290 Upper Wa rm Aisle 18 Genera l Purpose Cell (l) 3000 Uranium Load-Out Area <1 GPC Crane Room and Extension 7 Ura nium Product Cell 45 Head-End Ventilation Cell 610 Ventilation Exhaust Cell 67 Hot Acid Cell <1 Ventilation Wash Room 74 Liquid Waste Cell 1000 Low Ranking Area s (31 areas) 25 Lower Warm Aisle 84 Embedded Piping 110 (1) From WVES, 2008a, with estimates corrected for decay and ingrowth to September 30, 2004 and here rounded to two significa nt figures or the nearest whole number, with the exception of the embedded piping estimate, which is taken from McNeil 2005a . These estimates assume that the work to achieve the interim end state will include additional decontamination of the floors and walls in three areas: the General Purpose Cell, the Off-Gas Cell, and Process Mechanica l Cell . The estimates also assume that the vessels in the Acid Recovery Cell, the Hot Acid Cell, Extraction Cell 1, and Extraction Cell 3 have been removed.
Revision 2 4-17
WVDP PHASE 1 DECOMMISSIONING PLAN Despite decontamination efforts, radiation levels remain relatively high in some areas of the building . Table 4-7 shows the highest radiation levels measured in representative areas.
Table 4-7. Measured Maximum Gamma Radiation Levels in Process Building Areas Area mR/h Remarks Source Chemical Process Cell 15,000 At south sump in 1994 Michalczak 2003a Equipment Decontamination Room 50 On floor in 1997 Michalczak 2003b Fuel Receiving and Storage Area 8.5 Fuel Storage Pool, 2002 Fazio 2004a 500 Cask Unloading Pool. 2002 Fazio 2004a 1
General Purpose Cell 200,000 3 feet above floor( l Choroser 2005a 32 ,000 9 feet above floor(l) Choroser 2005a Head -E nd Ventilation Cell 50,000 On pre-filters in 2002 Michalczak 2003c Liquid Waste Cell 1,800 In 2002 Choroser 2004 Miniature Cell 80 In 1998 Michalczak 2002a Off-Gas Blower Room 700 In 2003 Michalczak 2002b Process Mechanica l Cell 40,000 In 2004, 3 feet above floor(l) Choroser 2005b Product Purification Cell 53 Hot spot on wall in 2003 Choroser 2003 Sample Storage Cell 1,950 On floor in 2001 Drobot 2003 Ventilation Wash Room 1,500 On ventilation duct URS 2001 (1) Before pl anned additional decontamination described in report WVES ZOOBa.
Radiation levels on the vitrified HLW canisters measured in the 1996 to 2002 period during vitrification ranged from 1,770 to 7,460 R/h (Michalczak 2003a) . The total activity in the average canister is approximately 37 ,000 curies, including approximately 13,600 curies of Sr-90 and approximately 23,400 curies of Cs -137, based on data in the waste form qualification report (WVES 2008f)6. The canisters remain stored in the HLW Interim Storage Facility in the former Chemical Process Cell, as noted previously.
Radioactivity in WMA 1, the Vitrification Facility Table 4-8 shows the estimated residual radioactivity in the Vitrification Facility at the beginning of Phase 1 decommissioning activities. Essentially all of this radioactivity is in the Vitrification Cell.
6 The estimated amounts of other radionuclides are as follows : 35 curies of Ni-63 , 189 curies of Sm-151, 19 curies of Pu-238, 5 curies of Pu-239, 4 curies of Pu-240, 175 curies of Pu-241 , 153 curies of Am-241 , 10 curies of Cm-242, and 35 curies of Cm-244 (WVES 2008f).
Revision 2 4-18
WVDP PHASE 1 DECOMMISSIONING PLAN Table 4-8. Estimated Total Activity in the Vitrification Facilityl 1J Nuclide Estimate (Ci) Nuclide Estimate (Ci) Nuclide Estimate (Ci)
Am-241 14 Np-237 0.01 Tc-99 0.04 C-14 <0.01 Pu-238 1.6 U-232 <0.01 Cm-243 0.09 Pu-239 0.49 U-233 <0.01 Cm-244 1.9 Pu -240 0.35 U-234 <0.01 Cs-137 960 Pu -241 8.7 U-235 <0.01 1-129 <0.01 Sr-90 910 U-238 <0.01 (1) From WVES 2008b, corrected for decay and ingrowth to 2011 and rounded to two significa nt figures or the nearest integer.
Gamma radiation levels in the Vitrification Cell process pit in 2004 after equipment removal and decontamination ranged from 3.1 to 50.5 R/h , with levels in other parts of the cell in the 1.2 to 18.1 R/h range (WVNSCO 2004b) .
Radioactivity in Other WMA 1 Facilities The 01-14 Building together with the vitrification off-gas line that runs to the building from the Vitrification Facility is estimated to contain in 2011 approximately 340 curies, due principally to Sr-90 and Cs-137 . Almost the entire amount is expected to be inside the off-gas line. The only place within the building itself where a significant amount of radioactivity is expected, besides the portion of the off-gas line in the building, is in the ventilation exhaust system filters (if these filters remain in place) . (Michalczak 2004c)
While the Plant Office Building, the Utility Room , the Utility Room Expansion, and the Load-In Facility have been impacted , they are expected to contain insignificant amounts of radioactivity. Radiation levels in these structures are expected to be <1 mR/h with no removable surface contamination above the minimum detectable concentration (Michalczak 2004b) .
Three underground wastewater tanks are located below grade outside of the Process Building: Tank 70-13, Tank 150-6, and Tank 35104 as shown in Figure 4-2. Tank 70-13 has been estimated to contain 150 to 300 gallons of solids containing up to 84 curies in 2011 , with the dominant radionuclides being Cs-137, Sr-90, Pu-241 , Am-241 , and Pu -239 (Michalczak 2004c). The other two tanks are not expected to contain significant amounts of radioactivity.
Most of the underground lines in WMA 1 are expected to be radioactively contaminated . A single line - HLW transfer line 7P120 was estimated to contain more than 90 percent of the total activity. This line runs from under the Chemical Process Cell to Tanks 80-3 and 80 -4 in WMA 3 and is expected . to contain residual radioactivity of approximately 0.4 curie per linear foot in 2011 , with almost all of this activity associated with Sr-90 and Cs-137 . Several of the underground lines within WMA 1 are known to have leaked as discussed in Section 2. (Luckett, et. al 2004)
Revision 2 4-19
WVDP PHASE 1 DECOMMISSIONING PLAN Radioactivity in WMA 2 Low-Level Waste Treatment Facility Area Facilities
- Low levels of radioactivity are expected to be present in the LLW2 Building. Lagoon 1 is expected to contain a substantial amount of radioactivity, with more than 90 percent in the remaining sediment. Table 2-19 shows the estimated amounts in 2011 .
Lagoon 2 is expected to contain residual radioactivity of the same order of magnitude as Lagoon 1 with a similar ra dionuclide distribution .7 Lagoon 3 is expected to contain less radioactivity in its sediment than Lagoons 1 and 2. Lagoons 4 and 5 are expected to contain rel atively low levels of radioactivity in sediment both above and below their liners.
Table 4-14 shows the maximum mea sured concentrations of radioactivity in sediment samples obtained from each of the lagoons.
The Old Interceptor is expected to contain a significant amount of radioactivity based on available data , which include a gamma radiation level of 408 mR/h measured near the tank bottom in 2003 (WVNSCO 2003) . As noted in Section 2, 12 inches of concrete was poured on the tank floor by NFS as radiation shielding . The New Interceptors and the Neutra lization Pit are both expected to conta in low levels of radioactive contamination .
The three septic tanks and other equipment in the Maintenance Shop leach field may have been impacted by the north plateau groundwater plume, but any resulting contamination levels are expected to be low.
The contaminated underground wastewater lines within WMA 2 were estimated to contain a total of approximately 0.3 curies of residual radioactivity in 2004 (Luckett. et al.
2004). The French drain is expected to contain very low levels of residual radioactivity.
Radioactivity in the WMA 3 Waste Tank Farm Area Facilities As explained in Section 1, only certain facilities and equipment within WMA 3 are within the scope of this plan. However, all WMA 3 facilities are briefly addressed here for perspective.
Table 2-5 in Section 2 provides estimates for the residual radioactivity in the underground waste tanks at the conclusion of reprocessing . Table 4-9 provides conservative estimates for residual radioactivity in the four underground waste tanks at the start of Phase 1 decommissioning activities. These estimates were based on a comprehensive characterization program that made use of sample analytical data and 8
radiation level measurements (WVNSCO and Gemini 2005) .
7 Thi s conclu sion is based primarily on record s showing th at 22.400 cubic feet of sediment were pumped from Lagoon 1 to Lagoon 2 in 1984, with this sediment conta ining appro ximately 107 curies of total alpha activity and 1162 curi es of total beta activity (Passuite and Monsalve-Jones 1993). Tabl e 4-14 shows maximum measured radionu clide con centrations in th e two lagoons, with Cs- 137 concentrations being th e same order of magnitude.
8 These estim ates addressed NRC comments provided on earlier ch ara cterization reports (NRC 2003) . The characterization report (WVNSCO and Gemini 2005) included three different estimates : best ca se, conservative ca ses, and worst case. The cons ervative case on whi ch Table 4-9 is based is considered to be Revision 2 4-20
WVDP PHASE 1 DECOMM ISSIONING PLAN 1
Table 4-9. Estimated Radioactivity in the Underground Waste Tanks l J Nuclide Estimate (Ci) Nuclide Estimate (Ci) Nuclide Estimate (Ci)
Am-241 391 Np-237 0.55 Tc-99 12 C-14 0.036 Pu-238 164 U-232 0.90 Cm-243 3.6 Pu-239 39 U-233 0.34 Cm -244 80 Pu -240 28 U-234 0.14 Cs- 137 301,000 Pu-241 '578 U-235 0.005 1-129 0.018 Sr-90 35.400 U-238 0.039 NOTE : (1) From WVNSCO and Gemini 2005 and from WVES 2008c, corrected for decay and ingrowth to 2011 and rounded to two significa nt figures or a single integer.
lri October 2009, the liquid levels in inches from ~he tank bottoms were as follows :
Tank 80 7.75 inches Tank 80 <2.5 inohes Tank 80 28.0 inches Tank 80 78 .8 inches.
Preparations were being made in late 2009 to remove arid process liquid from Tank 80-4.
A Sampling and Analysis Plan for the Waste Tank Farm was prepared in 2009 (WVES 2009a). This plan provides for additional characterization of each of the four underground waste tanks . If this plan were to be fully implemented, it would provide additional data on residual radioactivity within eac-h tank, including in the Supernatant Treatment System equipment that is inside Tank 80-1 .
Note that conditions in the underground waste ta nks wrn change .after the Waste Tank Farm and Vault Drying System described in Section 3 begins operation. This system is designed to dry (remove) 2000-4000 gallons of liquid from Tank 80-1 per year and the same amount from Tank 80-2, along with 100-400 gallons of liquid from Tank 80-3 per year and this amount from Tank 80-4 (WVES 2009c). This system may be operational when Phase 1 decommissioning activities begin. The amounts of residual activity listed in Table 4-9 will diminish slightly as the liquid evaporates during drying system operation .
The tank mobilization and transfer pumps are expected to contain significant amounts of radioactive contamination . Radiation levels near the bottom of Pump 55-G-003 exceeded 50 R/hr when this pump was removed in 1998 (WVNSCO 1998a). An order-of-magnitude estimate of the residual radioactivity in this removed pump was approximately .
220 curies (WVNSCO 2001) . The mobilization pumps remaining in the tanks will likely be similarly contaminated . The transfer pumps in Tanks 80-1 and 80-2 will likely have more contamination , since HLW passed through the entire length of the pump, rather than impacting only the lower portion as with the mobilization pumps. The other suction pumps conservative beca use it provides adequate safety margins, yet it is also con sidered to be rea listi c. The best and worst case estimates provide th e lower and upper bounds on the rea listi c conservative case .
Revision 2 4-21
WVDP PHASE 1 DECOMMISSIONING PLAN in Tanks 80-1 and 80-2 that are described in Section 3 will likely have somewhat lower contamination levels than the mobilization and transfer pumps .
As explained in Section 3, the transfer pumps in Tanks 80-3 and 80-4 will be removed before Phase 1 of the decommissioning and replaced with small submersible pumps.
These submersible pumps are expected to contain much lower levels of contamination than the other transfer pumps .
The piping and equipment in the HLW transfer trench also contains significant amounts of residual radioactivity . Radiation levels measured in the trench in 2004 ranged from 0.6 to 9.6 mR/hr. Levels in the pump pits in 2003 ranged from background at the top of Pit 80-1 to 33 .5 R/hr inside Pit 80-2 . Conservative estimates indicated that the pump pits and the diversion pit contained approximately 440 curies and the transfer piping approximately 234 curies in 2004, with the dominant radionuclides being Cs-137 , Sr-90, Am-241 , Pu -241 , and Cm -244, in that order. The transfer trench itself is not expected to be radiologically contaminated . (Fazio 2004b)
The equipment in the M-8 pump pit for Tank 80-2 was estimated to contain approximately seven curies in 2004 . Radiation levels up to 1.2 R/h were measured in the pit in 2000. (Fazio 2004b)
The Permanent Ventilation System Building is expected to contain a significant amount
- 1. of activity inside the ventilation filter housing, but most other areas in the building typically show no removable contamination above minimum detectable concentrations.
In the Supernatant Treatment System Support Building, radiation levels as high as 8.2 R/hr were measured in the valve aisle in 2003 . The valve aisle was conservatively estimated to contain 213 curies of residual radioactivity in 2004 (Fazio 2002c). Other areas of the building are not expected to contain significant radioactive contamination .
In the Equipment Shelter, most of the radiological inventory is expected to be located inside the ventilation system equipment. Radiation levels measured in 2003 ranged from 0.1 to 2.8 mR/hr. (Fazio, 2004b)
The Con-Ed Building is also radiologically contaminated, with the majority of the radiological inventory located inside the piping and equipment. Radiation levels measured in 2003 were typically 0.1 mR/hr (Fazio, 2004b) .
The total activity in the 40 underground lines in the immediate vicinity of the Waste Tank Farm has been estimated to be approximately 117 curies in 2004, with more than 99 percent of this activity associated with Cs-137 and Sr-90 (Luckett, et al. 2004).
Radioactivity in the Construction and Demolition Debris Landfill in WMA 4 Much of the buried waste in the landfill, which was not radioactive when it was emplaced, is now expected to have low-levels of radioactive contamination, mostly Sr-90, from the north plateau groundwater plume, which is addressed in Section 4.2.
Revision 2 4-22
WVDP PHASE 1 DECOMMISSIONING PLAN Radioactivity in the Facilities in WMA 5, the Waste Storage Area In WMA 5, Lag Storage Addition 4 and the attached shipping depot are expected to contain only low levels of radioactive contamination. if any. The Remote-Handled Waste Facility is expected to contain only low levels of contamination after it is deactivated . Most of the residual radioactivity is expected to be in the Work Cell where high activity waste and equipment are being packaged for disposal.
Radioactivity in the Facilities in WMA 6, the Central Project Premises The only facilities in WMA 6 that had been impacted by licensed radioactivity or the WVDP as of 2009 are the two demineralizer sludge ponds. which are addressed in Section 4.2, and the Cooling Tower basin . However, portions the Sewage Treatment Plant may contain radioactivity concentrations above background from sewage sludge which tends to concentrate naturally occurring radionuclides (ISCORS 2005) .
Radioactivity in the NOA in WMA 7 The buried waste in the NOA is known to contain a large amount of radioactivity which 9
has been estimated to total approximately 1B0,000 curies in 2011 as shown in Table 4-10.
Table 4-10 . Estimated Radioactivity in the NDAl1>
Nuclide Estimate (Ci) Nuclide Estimate (Ci) Nuclide Estimate (Ci)
Am-241 2,000 Np-237 0.17 Tc-99 10 C-14 520 Pu-238 350 U-233 11 Co-60 7,000 Pu-239 580 U-234 0.59 Cs-137 29,000 Pu-240 400 U-235 0.12 H-3 35 Pu-241 9,100 U-238 1.5 1-129 0.022 Ra-226 <0.01 - -
Ni-63 110,000 Sr-90 22,000 - -
NOTE: (1) From URS 2000, corrected for decay and ingrowth to 2011 and rounded to two significant fig ures.
Radioactivity in the Radwaste Treatment System Drum Cell in WMA 9 The Drum Cell - the only facility in WMA 9 and which is to be removed during Phase 1
- is expected to contain only low levels of residual radioactivity, if any.
WMA 10, the Support and Services Area None of the facilities to remain within WMA 10 at the time the Phase decommissioning activities begin had been impacted by site radioactivity as of 2009 .
9 This table, which is th e same as Table 2-21 in Section 2, is included here for completeness.
Revision 2 4-23
WVDP PHASE 1 DECOMMISSIONING PLAN 4.2 Radiological Status of Environmental Media Section 4.2 describes the radiological status of surface soil, sediment, subsurface soil, surface water, and groundwater within the project premises as compared with background .
NOTE Environmental media have not been fully characterized and, as a result, certain information normally included in decommissioning plans is not available. Additional characterization is planned in connection with the Phase 1 decommissioning work as described in Sections 7 and 9.
Additional characterization of subsurface soil was performed in 2008 . This characterization focused on hazardous contaminants and radionuclides in the source area of the north plateau groundwater plume (Michalczak 2007). The results have been incorporated into this plan .
The information provided below represents a compilation of environmental radiological data collected as part of the routine WVDP Environmental Monitoring and Groundwater Monitoring programs . It also includes data from nonroutine investigations designed to satisfy regulatory requirements (e .g., RCRA facility investigations) and other focused sampling activities.
Section 2.3 contains information on documented spills of radioactivity that have impacted environmental media on the project premises. These spills include the 1968 airborne radioactivity releases that produced the widespread area of surface contamination northwest of the Process Building known as the cesium prong and the release of radioactive acid under the southwest corner of the Process Building that resulted in the area of subsurface soil and groundwater contamination known today as the north plateau groundwater plume. This section focuses on environmental media conditions that exist today and duplicates information in Section 2.3 only where necessary for clarity.
Information in Section 4.2 is organized as follows :
- Section 4.2.1 identifies data sources used for this evaluation .
- Section 4.2.2 summarizes background levels of (1) radionuclide concentrations in surface soil, subsurface soil, stream sediment, surface water, and groundwater; and (2) environmental radiation .
10
- Section 4.2.3 summarizes radiological status of surface soil and sediment within the project premises.
- Section 4.2.4 provides the same information on subsurface soil.
10 Sediment in this context includes stream sediment, lagoon sediment, and drainage ditch sediment.
Revision 2 4-24
WVDP PHASE 1 DECOMMISSIONING PLAN
- Section 4.2 .5 summarizes maximum radionuclide concentrations at locations in each WMA where background levels were exceeded in soil, sediment, and subsurface soil.
- Section 4.2.6 provides information on environmental radiation levels on the project premises .
- Section 4.2.7 provides information on the radiological statu s of surface water on the project premises .
- Section 4.2.8 addresses the radiological status of groundwater on the project premises and, in particular, the north plateau groundwater plume.
Appendix B, Environmental Radioactivity Data, provides the following information :
- A description of how background radionuclide concentrations and environmental radiation levels were estimated;
- Maps showing locations where background data were taken ;
- Summary statistics applicable to each medium;
- A description of how data from onsite sampling programs were evaluated to determine if radiological concentrations or environmental radiation levels were above background ;
- Tables summarizing the ratios of above-background concentrations of radionuclides with Cs-137 in surface soil, sediment, and subsurface soil ;
- Additional summary information about radiological concentrations from routine onsite sampling locations;
- Descriptions of both impacted and non-impacted locations; and
- Tables that list the coordinates and descriptions of groundwater sampling locations, along with the depths and geologic units at which samples were collected .
4.2.1 Data Sources Radiological data on surface soil, sediment, subsurface soil, surface water, groundwater, and environmental radiation levels were taken from the WVDP Laboratory Information Management System controlled database, which contains environmental data from 1991 through the present. This system is used to manage data from the WVDP Environmental Monitoring and Groundwater Monitoring Programs, as well as data from special sampling activities (e.g., RCRA facility investigations, north plateau groundwater plume investigations) .
If necessary (i.e., if only pre-1991 data were available for an area), data were drawn from historical sources or summaries included in reports from previous evaluations .
Previous Evaluations Radiological data from environmental media have been presented in formal reports, for example:
Revision 2 4-25
WVDP PHASE 1 DECOMMISSIONING PLAN (1) WVDP Annual Site Environmental Reports (years 1982 through 2008 available on the Internet at www .wv.doe.gov);
(2) Groundwater trend analysis reports; (3) Reports of RCRA facility investigations of various areas of the WVDP (WVNSCO 1995, WVNSCO 1996, WVNSCO 1997a, WVNSCO 1997b, WVNSCO and Dames
& Moore [D&MJ 1996a, WVNSCO and D&M 1996b, WVNSCO and D&M 1997a, WVNSCO and D&M 1997b, and WVNSCO and D&M 1997c); and (4) Results from north plateau groundwater plume investigations (Carpenter and Hemann 1995, WVNSCO 1998, URS 2002, Klenk 2009, Michalczak 2009b, and WVES and URS 2009). The RCRA Facility Investigations and the north plateau investigations produced a substantial body of soil characterization data, most associated with nonradiological constituents.
Data Quality WVDP environmental samples evaluated in this plan were collected in accordance with formal sampling plans. Samples were analyzed by onsite and offsite laboratories in accordance with controlled procedures as required by the WVDP quality assurance (QA) program . QA requirements applicable to the sampling programs include documented training of field personnel; controlled collection procedures; using appropriate containers, preservatives, and storage methods to protect samples from contamination and degradation; following appropriate field and analytical quality control guidelines; maintaining and documenting chain-of-custody; and conducting assessments and audits of field and analytical processes to verify compliance.
Data were validated by a separate data validation group, and validation and approval status of sample results were documented in the Laboratory Information Management System .
4.2.2 Background Levels This subsection addresses background radioactivity in environmental media on the project premises and provides information on background radiation levels .
Background Radionuclide Concentrations in Environmental Media Radionuclides for which backgrounds were estimated were selected with consideration of (1) radionuclides of interest from the Facility Characterization Project, listed in section 4.1.1, and (2) radionuclides that are routinely monitored in environmental media at the WVDP, for which sufficient data were available to develop a reliable estimate of background .
Background radionuclide concentrations were estimated for soil, sediment, subsurface soil, surface water, and groundwater for the following radionuclides:
Sr-90 U-232 U-235/236 Pu-238 Am-241 Cs-137 U-23 3/234 U-238 Pu -239/240 Revision 2 4-26
WVDP PHASE 1 DECOMMISSIONING PLAN Pu-241, Cm-243, Cm-244, and Np-237, which are radionuclides of interest in the Facility Characterization Project. are not routinely measured in environmental media at the WVDP so were not included in background estimates.
In addition, background concentrations were estimated for surface water and groundwater for the following radionuclides that were not routinely analyzed in soil and sediment:
H-3 C-14 Tc-99 1-129 Although tritium (H-3) is not identified in Section 4.1.1 as a radionuclide of interest. it is commonly found in surface water and groundwater samples at the WVDP and so was included in the radionuclide listing for environmental media . In addition, gross alpha and gross beta measurements are routinely used as screening (i.e., "surrogate" or "indicator")
parameters for other radionuclides, so backgrou.nd concentrations were estimated for gross alpha and gross beta activity. (For instance, gross beta measurements are used as a surrogate for Sr-90 measurements in the WVDP Groundwater Monitoring Program .)
Appendix B provides maps showing locations from which background data were taken and a description of how background concentrations were estimated . Appendix B also includes a table of summary statistics (e.g., number of samples, percentage of nondetect 11 values, average concentrations, medians) for each constituent in each medium . Median and maximum background concentrations are summarized in Table 4-11.
Table 4-11 . Median and Maximum(i) Background Concentrations for Environmental Media at the WVDP Surface soil Subsurface soil Sediment Surface water Groundwater Constituent (pCi/g dry) (pCi/g dry)t2l (pCi/g dry) (pCi/L) (pCi/L) 1.3E+01 1.3E+01 9.2E+OO <9.6E-01 <2.6E+OO Gross alpha (2.7E+01) (1.7E+0 1) (2.2E+01) (5.4E+OO) (2.2E+01 )
2.0E+01 2.9E+01 1.6E+01 2.3E+OO 4.6E+OO Gross beta (4.0E+01) (6.1E+01) (2.7E+01) (2.0E+01) (2.8E+01)
<8.2E+01 <8.6E+01 H-3 NA NA NA (6.3E+02) (9.4E+02)
<1 .3E+01 <2.7E+01 C-14 NA NA NA (4.1E+02) (7.4E+OO) 9.5E-02 <2.3E-02 <3.4E-02 9.0E-01 2.4E+OO Sr-90 (3.1 E+OO) (1.2E-01) (1.6E-01) (1 .2E+01) (7.4E+OO)
<1 .8E+OO <1 .8E+OO Tc-99 NA NA NA (7.3E+OO) (4.0E+OO) 1-129 NA NA NA <7.9E-01 <6.0E-01 11 Note that if a data set is symmetric, the average (i .e., mean) and the median will be the same. However, if the distribution is skewed to the right (i.e. , contains a large number of low values and a few high values), the average will usually be higher than the median . For this reason, the median may be the more reliable estimator of central tendency. In this evaluation, both were estimated and are presented in Appendix B.
Revision 2 4-27
WVDP PHAS E 1 DECOMM ISSIONING PLAN Table 4-11 . Median and Maximum(l) Background Concentrations for Environmental Media at the WVDP Surface soil Subsurface soil Sediment Surface water Groundwater Constituent (pCi/g dry) (pCi/g dry)(2l (pCi/g dry) (pCi/L) (pCi/L)
(2.0E+OO) * (1 .6E+OO) 4.2E-01 <2.4E-02 3.8E-02 <4.2E+OO <2.2E+01 Cs-137 (1 .2E+OO) (1.5E-01 ) (7.8E-02) (1.0E+01 ) (1.9E+0 1)
<2.4E-02 <2.4E-02 <3. 1E-02 <4.3E-02 <4.9E-02 U-232 (1 .9E-02) (<4.2E-02) (3.9E-02) (2.6E-01 ) (3.8E-01) 7.9E-01 7.9E-01 6.6E-01 9.9E-02 1.6E-01 U-233/234 (9.4E-01) (1 .1E+OO) (8.6E-01) (3.0E-01) (8.2E+OO) 5.2E-02 4.2E-02 4.6E-02 <3.3E-02 <5.0E-02 U-235/236 (2.2E-01 ) (1 .2E-01) (2.8E-01) (1.0E-01) (1 .9E-01) 7.9E-01 8.6E-01 6.5E-01 5.7E-02 1.2E-01 U-238 (9.3E-01) (1 .1E+OO) (9.0E-01 ) (4. 0E-01 ) (5.3E+OO)
<1.2E-02 <1 .2E-02 <1.4E-02 <3.1E-02 <4.6E-02 Pu-238 (4.0E-02) (<2.4E-02) (1 .3E-01) (1.0E-01) (2.2E-01) 1.6E-02 <1.0E-02 <1.2E-02 <2.7E-02 <5.3E-02 Pu-239/240 (2.3E-01) (<1 .9E-02) (6.1E-02) (2.0E-01) (2.7E-01)
<1 .6E-02 <1 .1E-02 <1.4E-02 <3.3E-02 <3.8E-02 Am-241 (1 .9E-01) (<1.3E-02) (8.6E-02) (2.2E+OO) (1 .8E-01)
NOTE : (1) Maxima are in parentheses. Maxima were selected from samples in which the radionuclide was detected (i.e., a "nondetect" result, indicated by a "<" sign, was used only if no detectabl e results were available) .
(2) This column was add ed after sufficient background soil samples were collected in 2008 to allow for compari son purposes.
LE GEND: NA = Not analyzed in this medium Data on radionuclide concentrations in environmental media on the project premises were evaluated to determine the locations where radionuclide concentrations in excess of site background levels were found . Methods for evaluating sample data with respect to background were dependent on the type of data available for comparison (e.g ., a single sample result, a data set encompassing several years) . Methods for each are described in Appendix B.
Data evaluated in Section 4.2 were taken from samples collected over several years.
Whi le the majority of data points were from 1991 through 2008 , the earliest was from a sampl e collected in 1967.12 In Section 4.1, radionuclide activities in facilities on the project premises were decay-corrected to the year 2011 . However, in Section 4.2 no attempt wa s 12 Note that hi storica l and current data, whi ch were generated over more than 40 years of NFS and WVDP operations, may not be directly comparable because different sampling and analytical methodologies have been used over th e years . Hi storical and current data were compared with background con centrations using different stati sti ca l method s, as described in Appendix B.
Revision 2 4-28
WVDP PHASE 1 DECOMMISSIONING PLAN made to decay-correct results from environmental samples because, unlike process cells or tanks, environmental media are not closed , static systems .
Media such as surface soil, sediment, subsurface soil, surface water, and groundwater are all subject to forces (aside from radioactive decay) with the potential to modify their radionuclide concentrations. Forces such as weathering , biological activity, atmospheric fallout, surface water runoff, wind erosion, and evaporation may act to deposit or remove radionuclides from a medium . Also, radionuclides are affected differentially by these mechanisms (e .g., Sr-90 is more mobile in water than Cs-137 , which is more likely to bind to clay particles in soil and sediment) .
Many of the radionuclides considered in this section are long-lived and it is unlikely that decay-correction would have affected the determination of whether or not background concentrations were exceeded. However, it is possibl e that estimates of radiological concentrations of the shorter-lived radionuclides (i .e., tritium [half-life of 12.3 years], Sr-90
[half-life of 28.9 years], and Cs-137 [half-life of 30 years]) are conservatively high, that is, overestimates .
Background Environmental Radiation Levels Radiation levels have been measured at the WVDP from 1986 through the present with 13 a network of environmental thermoluminescent dosimeters (TLDs). Average quarterly exposure measurements from four background locations over this time period was 19.3 mR per quarter (about 8.8E-03 mR/h). The maximum for any single quarter was 35 mR/quarter (about 1.6E-02 mR/h) .
Background environmental radiation levels were used to evaluate measurements from onsite TLDs near process facilities, waste storage areas, and burial areas . (See Appendix B for a map showing the locations of background TLDs . See section 4.2.6 for a discussion of onsite exposure measurements.)
4.2.3 Radiological Status of Surface Soil and Sediment Since the facility has operated, numerous soil sampling studies have been conducted onsite, not as part of a formal site-wide soil program, but rather as area-specific investigations in response to specific circumstances or events (WVNSCO 1994). In 1993, a site-wide soil sampling program was conducted to obtain additional data to support the EIS and RCRA processes . As part of this program, surface soil, sediment, and subsurface soil samples were collected . Results were summarized in WVNSCO 1994.
NUREG-1757 (NRC 2006) defines surface soil as the soil within the top 15 to 30 cm (six to 12 inches) of the soil column . That definition has been broadened in this plan to include soil within the top 60 cm (O to two feet) of the soil column . This was done so that 13 While radiation levels were measured at the WVDP prior to 1986, the current methodology has been used only since 1986. Therefore. for comparabi lity, only data generated from 1986 through the present were used in th e background calcu lation .
Revision 2 4-29
WVDP PHASE 1 DECOMMISSIONING PLAN available data from the top interval (O to two-foot depth) from onsite soil -borings collected as part of the 1993 program could be used to assess the radiological status of surface soil.
Data from the subsurface portions of the boreholes (i .e., at depths greater than two feet) are discussed in section 4.2.5.
Areas With Radionuclide Concentrations in Excess of Site Background Levels Figure 4-6 shows locations at which radiological concentrations exceeding background were noted in surface soil and sediment for (1) gross alpha or alpha-emitting radionuclides and (2) gross beta or beta-gamma emitting radionuclides. 14
- The highest radionuclide concentrations were found in sediment from the lagoons in the WMA 2 Low-Level Waste Treatment Facility. See Table 4-14 for a listing of maximum radionuclide concentrations above background noted in the lagoon and drainage system. The highest radionuclide concentrations were noted in sediment from Lagoon 2. (Although higher concentrations are listed for Lagoon 1, the Lagoon 1 sediment was transferred to Lagoon 2 when Lagoon 1 was deactivated in 1984.)
- Cs-137 concentrations in excess of background were fo.und in surface soil samples from all waste management areas at which samples had been collected . Although no surface soi l data were available from WMA 1 (the Process Building and Vitrification Facility area) , it is suspected that radionuclide concentrations in excess of background will be found here based on proximity to the Process Building and the elevated concentrations observed in adjoining WMAs . The highest levels noted in surface soil from other areas (i .e., 2.8E +02 pCi/g in WMA 2 near the Interceptors, 1.6E+02 pCi/g in WMA 6 near the Fuel Receiving and Storage Area and 2.3E+01 pCi/g in WMA 3 near the Waste Tank Farm) were all from areas in closest proximity to WMA 1. Elevated Cs-137 concentrations are thought to be largely attributable to historical releases and continuing low-level airborne releases from the main stack of the Process Building.
- Surface soil concentrations of Sr-90 exceeding background were noted in several areas, most notably in areas affected by the north plateau groundwater plume, such as WMA 2 (the Low-Level Waste Treatment Facility area) and WMA 4 (the area of the Construction and Demolition Debris Landfill) .
- Radionuclide concentrations exceeding background , primarily from Sr-90 and Cs-137 , were found in sediment samples from streams and drainage ditches in several waste management areas (WMAs 2, 4, 5, 6, 7, 10, and 12) . Concentrations of alpha-emitting radionuclides (i.e .. U-232, Pu-238, Pu-239/240, and/or Am -241) in 14 WMA 12 is not labeled on the figures in this section because it extends to the boundaries of th e Center.
Areas on the project premises (i .e .. within the security fence) that are considered to be part of WMA 12 include (1) the area between the north and south plateaus. which contai ns much of the drainage for Erdman Brook and Franks Creek, and (2) a small area north of WMA 4.
Revision 2 4-30
WVDP PHASE 1 DECOMMISSIONING PLAN excess of background were also noted in WMAs 2, 4, 5, 7, and 12 downgradient of liquid release points or waste burial areas.
- High radionuclide concentration levels were also associated with soil and sediment from the area of the Old Interceptors, the Solvent Dike, and inactive (filled-in)
Lagoon 1 in WMA 2.
- South plateau areas with radionuclide concentrations exceeding background in surface soil include the two former shallow land burial disposal facilities, the NOA (WMA 7) and SDA (WMA 8) . Elevated radiological concentrations in the surface 15 and near-surface soils in the vicinities of those facilities is expected due to the nature of their operations. (As noted previously, WMA 8 is not within plan scope.)
Levels at which radionuclide concentrations in excess of background were found in surface soil and sediment are listed by WMA in the tables in section 4.2.5. As shown in Figure 4-6, only one surface soil sampling location (SS-11) had no concentrations exceeding background . All sediment sampling locations had at least one constituent exceeding background .
4.2.4 Radiological Status of Subsurface Soil Figure 4-7 shows locations at which concentrations of radiological constituents above background were noted in subsurface soil for (1) alpha-emitting radionuclides and (2) beta-gamma emitting radionuclides .
NOTE The information provided below does not include data from characterization measurements for Sr-90 in subsurface soil, surface water, and groundwater collected during a 2008-2009 investigation to support design of mitigation measures for the leading edge of the north plateau groundwater plume . The results of this characterization can be found in report WVDP-500 (WVES 2009b) .
This characterization program focused on conditions in the northern part of WMA 2 and in WMA 4. Direct-push soil borings and groundwater samples were obtained using a Geoprobe unit. A total of 63 soil samples were analyzed for Sr-90. In addition, 74 microwells were installed to collect groundwater in the sand and gravel unit.
Data from this characterization program has redefined the leading edge of the north plateau groundwater plume, which is now known to form three small lobes as shown in Figure 4-14. This configuration appears to result from the uneven distribution of coarse and fine sediment within the sand and gravel unit, which affects local groundwater flow rates .
15 Near-surface in this context means a few feet from the surface.
Revision 2 4-31
WV DP PHASE 1 DECOMMISSIONING P LAN r*
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- Revision 2 4-32
WVDP PHASE 1 D EC OMMI SSIONING PLAN
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Background
Revi sion 2 4-33
WVDP PHASE 1 DECOMMISSIONING PLAN Most subsurface soil data were taken from the 1993 RCRA Facility Investigation sampling program and three Geoprobe sampling efforts {1994, 1998, and 2008) to better define the origin and extent of the north plateau groundwater plume.
The highest subsurface radiological concentrations on the north plateau were observed in WMA 1 (the Process Building and Vitrification Facility area), WMA 2 (the Low-Level Waste Treatment Facility area}, and WMA 6 (the Central Project Premises).
downgradient of the Process Building. On the south plateau, highest concentrations were from WMA 7 (the NOA) . Subsurface soil concentrations exceeding background were primarily associated with the north plateau groundwater plume (see Section 2) or with former waste processing or burial activities. Figure 4-8 presents a cross -section of Sr-90 concentrations in subsurface soil with depth in the north plateau below the Process Building . Data from this cross-section were taken from samples collected in 1993, 1994, 1998, and 2008 from WMAs 1, 2, and 6. The highest concentrations of Sr-90 were observed in the sand and gravel unit below the water table.
In WMA 1, high levels of Sr-90 were measured during the Geoprobe investigations near the Process Building . In WMA 2, the highest levels of both beta-gamma and alpha-emitting radionuclides in subsurface soil were observed in sediments from borings taken near the Solvent Dike, the interceptors, and the Maintenance Shop leach field. In WMA 6, elevated subsurface soil concentrations were noted near the Utility Room and the Fuel Receiving and Storage Building . Data from WMA 7 were taken from rolloffs and boxes containing excavated soil generated at or near the NOA. Soil was largely from the Interceptor Trench, immediately downgradient of the NOA, when it was installed in 1990, and from nonspecific "special holes" (WVNSCO 1997c) . Although the packaged soil has since been shipped offsite, it is likely that radionuclide concentrations in subsurface soil remaining in the NOA will be similar to those from the excavated soil.
Concentrations of radionuclides observed in excess of background levels in subsurface soils are summarized in Section 4.2.5.
Revision 2 4-34
WVDP PHASE 1 DECOMMISSIONING PLAN Figure 4-8. Cross-section of Sr-90 Concentrations Versus Depth in Subsurface Soil in WMA 1 Revision 2 4-35
WVDP PHASE 1 DECOMMISSIONING PLAN 4.2.5 Radionuclide Concentrations Exceeding Background in Surface Soil, Sediment, and Subsurface Soil By WMA The following tables summarize locations in each WMA where radionuclide concentrations were noted in excess of background . (See Table 4-11 and Appendix B for background radionuclide concentrations used to evaluate soil, sediment. and subsurface soil.) Data from surface soil, sediment. and subsurface soil are combined into one table for each WMA, except for WMA 2, where data are presented in three tables due to the large volume of information .
For each area, the maximum concentration at which the radionuclide was found is listed, together with source . and location (i .e .. reference or specific sample identifier) .
Identifiers from the 1993 RCRA Facility Investigation sampling program are specified as boreholes ("BH -"), surface soil ("SS -") or stream sediment ("ST-"). Subsurface Geoprobe soil sample locations are designated "GP ." For subsurface soil, the depth at which the maximum was noted (if available) is also provided . Gross alpha and gross beta measurements are not presented because the measurements represent a mix of radionuclides (including those naturally occurring) . and because data for specific alpha-and beta-emitting r.adionuclides were available. Ratios of above-background radionuclide concentrations to Cs-137 are presented in Appendix B in Tables B-9 (Surface Soil) , B-10 (Sediment). and B-11 (Subsurface Soil) .
WMA 1, Process Building and Vitrification Facility Area Limited data are available for WMA 1, none for surface soil or sediment. Most subsurface soil data were taken from the Geoprobe Investigations in 1994, 1998, and 2008, and from three borehole locations from the 1993 RCRA Facility Investigation .
Additional data were taken from one sample collected in 2004 near a breach in an underground wastewater line near the laundry.
Above-background concentrations in subsurface soil from WMA 1 were noted for Sr-90, Cs-137. U-232. U-233/234, U-235/236, U-238, Pu -238 , Pu-239/240, and Am-241.
Maximum radionuclide concentrations are listed in Table 4-12. Except for the Cs-137 and Am-241 maxima observed from the sample near the laundry line breach, all maxima were from samples taken in 2008 under the Process Building. Maxima from Geoprobe locations were found at depths of 14 to 42 feet in the saturated layer of the sand and gravel unit.
High ratios of Sr-90 to Cs-137 observed in WMA 1 (with a median ratio of about 300 to 1 and a maximum ratio of over 63,000 to 1 [see Table B-11 in Appendix BJ) reflect the influence of the north plateau groundwater plume . Maximum ratios of other radionuclides to Cs-137 in WMA 1 were : U-232 (0 .023 to 1). U-233/234 (12 to 1), U-235/236 (1 .1to1), U-238 (18 to 1) , Pu -238 (0 .18 to 1). Pu -239/240 (0 .80to1) and Am-241 (2 .7 to 1) .
Revision 2 4-36
WVDP PHAS E 1 D ECOMMISSIONI NG PLAN Table 4-12. Above-Background Concentrations of Radionuclides in Subsurface Soil atWMA 1(1l Maximum Concentration (pCi/g dry)
Location U-233/ U-235/ Pu-239/
Cs-137 Sr-90 U-232 U-238 Pu-238 Am-241 234 236 240 l\lnln I?) 3.3E+03 9.3E+03 5.0E-02 1.9E+OO 2.2E-01 1.7E+OO 5.6E-01 3.7E+OO 8.7E+01 NOTES : (1) See Figure 4-2 for a map of facilities in WMA 1.
(2) Sampling related to laundry line breach in 2004 (Cs-137, Am-241 ); Geoprobe sampling underneath Process Building in 2008 (GP7608 at 15-17' depth [Sr-90] ; GP10408 at 20-22' depth
[U-232]; GP7608 at 38-40' depth [U-233/234]; GP8308 at 40-42' depth [U-235/236]; GP2908 at 14-16' depth [U-238], GP7608at19-21 ' depth [Pu-238, Pu-239/240] .
WMA 2, Low-Level Waste Treatment Facility Area Extensive data, available both electronically and from historical reports, were available for WMA 2. The maximum concentrations observed at each location within WMA 2 are
' listed below. Due to the large volume , data are presented in three tables: Table 4-13 (surface soil), Table 4-14 (sediment) , and Table 4-15 (subsurface soil) .
The radionuclides observed above background in surface soil (Table 4-13) were Cs-137 and Sr-90. The maximum ratio of Sr-90 to Cs-137 (about 1.4 to 1) was observed in surface soil north of Lagoons 4 and 5, which is affected by the north plateau groundwater plume. No alpha-emitting radionuclides were observed at concentrations above background in surface soil from WMA 2.
Table 4-13. Above-Background Concentrations of Radionuclides in Surface Soil From WMA 2(1l Maximum Concentration (pCi/g dry)
Location Cs-137 Sr-90 Surface soil near the Old and New 2.8E +02 4.1 E+OO Interceptors (BH-13)
Surface soil between the Interceptors and 1.4E+01 1.4E+OO inactive Lagoon 1 (WVNSCO 1994 [Tabl e 3-2] and BH-14)
Surface soil between inactive Lagoon 1 and 4.8E+OO 1.1 E+OO active Lagoon 2 (BH-08)
Surface soil from Maintenance Shop Leach 2.1 E+01 1.3E+OO Field (WVNSCO 1994 [Table 3-2] and BH -
35)
Surface soil near the LLW2 Facility (BH-36) ~Bkg 3.2E-01 Surface soil near the Vitrification Test 6.6E -01 ~Bkg Facility (BH-37)
Surface soil north of Lagoons 4 and 5 (BH- 8.5E-01 1.2E+OO 04)
Revision 2 4-37
WV DP PHASE 1 D ECOMMISSIONING P LAN Table 4-13. Above-Background Concentrations of Radionucl ides in Surface Soil From WMA 2(1l Maximum Concentration (pCi/g dry)
Location Cs-137 Sr-90 Surface soil between the lagoons and WMA 3.6E+OO 3.6E-01 4 (SS-03, SS-06)
Surface soil between the road and Lagoon 2 8.9E-01 :5Bkg (BH -33A)
LEGEND : " ~Bkg " = Background was not exceeded .
NOTE: (1) See Figure 4-3 for a map of facilities in WMA 2. Facilities not labeled in Fig. 4-3 include the former Maintenance Shop (which was located southwest of the LLW2 Facility), and the Vitrification Test Facility (located northwest of the LLW2 Facility) . See Figure 4-6 for a map with the above sampling locations.
Radionuclides observed above background in sediment (Table 4-14) were Cs-137, Sr-90, U-232, U-233/234, U-235/236, U-238, Pu-238, Pu -239/240, and Am-241 . Maximum ratios to Cs-137 for each were : Sr-90 (144 to 1), U-232 (0.0054 to 1), U-233/234 (0.056 to 1), U-235/236 {0.011 to 1), U-238 {0.057 to 1), Pu-238 {0.018 to 1), Pu-239/240 (0.019 to 1), and Am-241 (4.2 to 1). (See Appendix B, Table B-10, for a summary of radionucl ide ratios in sediment from WMA 2.)
Maximum ratios to Cs-137 were found in sediment from (or downgradient of) the Solvent Dike (Sr-90, U- 233/234, U-235/236, Pu- 239/240, and Am-241), sediment from Lagoon 3 {U- 232 and U-238), and sed iment from the Lagoon 2 shoreline (Pu- 238) . The highest Am-241 to Cs-13 7 ratio (4 .2 to 1) was from one Solvent Dike sediment sample collected in 1986. For comparison , the median Am-241 to Cs-137 ratio in WMA 2 was 0.001 9 to 1.
Tabl e 4-14. Above-Backg round Concentrations of Radionuclides in Sed iment From WMA 2 Maximum Concentration (pCi/g dry)
Location U-233/ U-235/ Pu-239/
Cs-137 Sr-90 U-232 U-238 Pu-238 Am-241 234 236 240 Sediment from drainage 2.0E+OO 3.5E-01 NA NA NA NA NA NA NA north of Test and Storage Building (ST-34)
Sediment from Solvent 3.1E+02 1.6E+03 NA NA NA NA NA NA 1.1 E+03 Dike (WVN SCO 1994, Table 3-12, 1986 samples)
Sediment from drainage 1.7E+01 2.9E+OO :5Bkg 9.5E-01 :5Bkg :5Bkg 2.9E-01 3.2E-01 7.1E-01 downgradient of Solvent Dike (ST-28)
Sediment from Lagoon 1 4.7E+05 1.5E+05 NA NA NA NA 3.9E+04 1.8E+04 1.9E+04 (Passuite and Monsalve-Jones 1993, Tables 3-2
[1982 data) and 3-3 [1984 data])
Revision 2 4-38
WVDP PHASE 1 DECOMMISSIONING PLAN Table 4-14. Above-Background Concentrations of Rad ion ucl ides in Sed iment From WMA 2 Maximum Concentration (pCi/g dry)
Location U-233/ U-235/ Pu-239/
Cs-137 Sr-90 U-232 U-238 Pu-238 Am-241 234 236 240 Sediment from Lagoon 2.7E+05 3.6E+04 NA NA 6.5E-01 6.2E+OO 8.0E+02 6.4E+02 8.3E+02 2!1l (WVNSCO 1994, Tables 3-5 [1982 data]
and 3-8 [1990 data])
Sediment from Lagoon 3 1.1 E+04 7.7E+02 7.6E+OO 4.5E+OO 1.3E+OO 8.8E+OO 3.1 E+OO 1.4E+OO 5.1E+OO (WVNSCO 1994, Tables 3-11 [1990 data], 3-9
[1967 data]; and 1994 Lagoon 3 sampling)
Sediment from Lagoon 4 3.2E+01 7.3E+OO NA NA NA NA NA NA NA (1994 sampling)
Sediment from Lagoon 5 5.2E+01 4.1E+01 NA NA NA NA NA NA NA (1994 sampling)
NOTE : (1) In 1984, an estimated 22,400 cubic feet of sediment were pumped from Lagoon 1 to Lagoon 2 (Passuite and Monsalve-Jones 1993) so the 1982 sample results are not necessarily representative of th e of the activity in Lagoon 2 sediment.
(2) See Figure 4-3 for a map of facilities in WMA 2. The Test and Storage Building (which was located near the southwestern boundary of WMA 2) is not labeled in Fig . 4-3. See Figure 4-6 for a map with the above sampling locations.
LEGEND: NA ; No analysis. "SBkg"; Background was not ~xceeded.
Above-background concentrations in subsurface soil from WMA 2 were noted for Sr-90, Cs-137, U-232, U-233/234, U-235/236, U-238, Pu-238, Pu-239/240, and Am-241.
Maximum radionuclide concentrations at various points in WMA 2 are listed in Table 4-15 .
The highest concentrations of all radionuclides were found in saturated soil six-to-eight feet deep from one location (BH-8) downgradient of Lagoon 1. Other maxima were also found in samples taken under the Solvent Dike and downgradient of the interceptors in saturated soil in the sand and gravel unit.
As noted in the WMA 1 discussion, ratios of Sr-90 to Cs-137 were also elevated in WMA 2, downgradient of the source of the north plateau plume. However, ratios were much lower than in WMA 1 (i.e. , a median ratio of 1.9 to 1 and a maximum of 750 to 1 [as compared with the median of about 300 to 1 and the maximum of over 63,000 to 1 in WMA 1). Maximum ratios of other radionuclides to Cs-137 in WMA 2, as summarized in Table B-11, were : U-2 32 (1 to 1), U-233/234 (7 to 1), U-235/236 (1 .1 to 1), U-238 (4.4 to 1), Pu -238 (0.089 to 1), Pu-239/240 (0 .11to1) and Am-241 (0.23 to 1).
Revision 2 4-39
WVDP PHASE 1 DE COMMISSIONING PLAN Table 4-15. Above-Background Concentrations of Radionuclides in Subsurface Soil From WMA2 (1l .
Maximum Concentration (pCi/g dry)
Location U-233/ U-235/ Pu-239/
Cs-137 Sr-90 U-232 U-238 Pu-238 Am-241 234 236 240 Downgradient of 3.6E+04 1.5E+04 5.8E+02 2.7E+02 4.2E+OO 6.8E+01 6.8E+02 1.2E+03 1.7E+03 inactive Lagoon 1 (BH-08 at 6-8' depth)
Near Solvent Dike (BH- 1.8E+02 5.6E+01 :5Bkg 3.6E+OO 5.3E-01 2.2E+OO :5Bkg 7.5E-02 1.1E-01 11 at 8-10' depth, Cs-137 max at 2-4' depth)
Near the Old and New 5.2E+03 1.9E+02 5.1 E+01 2.4E+01 2.0E-01 3.7E+OO 6.6E+01 5.1E+01 5.3E+01 Interceptors (BH-13, 8-10' depth, U-238 max at 6-8' depth)
Between the 6.1E+OO 2.8E+01 1.0E-01 :5Bkg :58kg :58kg 1.7E-01 1.9E-01 2.8E-01 Interceptors and inactive Lagoon 1 (BH-14 at 4-6' depth, Pu-238 at 14-16' depth)
East of the former TSB 1.6E+01 3.9E+02 1.3E+OO :58kg :58kg :58kg 4.6E-01 7.4E-02 1.3E+OO (BH-35, 6-8' depth)
Downgradient of MPPB, :58kg 7.6E+02 :5Bkg :58kg :5Bkg :58kg :5Bkg :58kg :58kg near the former TSB
[GP10508, 28-30' depth)
Downgradient of MPPB, :5Bkg 6.6E+01 :58kg 9.0E-01 2.2E-01 :58kg :58kg :58kg 3.4E-02 south of the former Maintenance Shop (GP10608, at 20-22' depth [Sr-90) and at 22-24' depth [Am-241 , U isotopes])
Downgradient of MPPB, :58kg 3.8E+02 :5Bkg :58kg 1.9E-01 :5Bkg :58kg :5Bkg :5Bkg near Vit Test Facility (GP10708, at 30-32' depth [Sr-90) and at 12-14' depth [U-235/2361)
Downgradient of MPPB, :5Bkg 2.3E+02 1.3E-01 :58kg :58kg 1.0E+OO :58kg :58kg :58kg near area of the leach field for the former Maintenance Shop (GP10908, at 34-36' depth [Sr-90), and at 36-38' depth [U-232, U-2381)
NOTE: (1) See Figure 4-3 for a map of facilities in WMA 2. Facilities not labeled in Figure 4-3 include the former Maintenance Shop (which was located southwest of the LLW 2 Facility), and the Vitrification Test Facility (located northwest of the LLW2 Facility). See Figure 4-7 for a map with the above sa mpling locations.
LEGEND : ":sBkg"; Background was not exceeded . MPPB; Main Plant Process Building . TSB; Test and Storage Building .
Revision 2 4-40
WVDP PHASE 1 D ECOM MISSIONING PLAN WMA 3. High-level Waste Tank Farm Minimal data were available for the Waste Tank Farm . Table 4-16 lists maximum concentrations of radionuclides found in surface soil at levels above background. Data were from a 1990 sampling, as summarized in Table 3-2 of WVNSCO 1994.
Concentrations in excess of background levels were noted for Cs-137 , U-238, and Am-241 .
The ratios of U-238 and Am-241 to Cs-137 in surface soil from the Waste Tank Farm were 0.04 7, and 0.011 , respectively. No sediment or subsurface soil data were available, although subsurface soil concentrations exceeding background are expected because of leaks or breaches in transfer lines (see Section 2) and because of elevated radionuclide concentrations found in groundwater as discussed below.
Table 4-16. Above-Background Concentrations of Radionuclides in Surface Soil at WMA3(1l Maximum Concentration (pCi/g dry)
Location Cs-137 U-238 Am-241 Surface soil at the Waste Tank Farm 2.3E+01 1.1 E+OO 2.SE -01 (WVNSCO 1994, Table 3-2 (1990 data])
NOTE : (1) See Figure 4-4 for a map of faci lities in WMA 3 and Figure 4-6 for a map showing areas with above-background levels of radionuclides in surface soil.
WMA 4, Construction and Demolition Debris Landfill Area Concentrations of radiological constituents measured at levels in excess of background in surface soil, sediment, and subsurface soil from WMA 4 are listed in Table 4-17. Surface soil from WMA 4, a portion of which includes the landfill, was found to contain concentrations of Cs-137 and Sr-90 in excess of background . The maximum ratio of Sr-90 to Cs-137 in surface soil was about 9.5 to 1.
Table 4-17. Above-Background Concentrations of Radionuclides in Surface Soil, Sediment, and Subsurface Soil From WMA 4(1l
- Maximum Concentration (pCi/g dry)
Location U-233/ Pu-239/
Cs-137 Sr-90 U-238 Pu-238 Am-241 234 240 Surface soil along drainage though 9.1E+OO 1.2E+01 NA NA NA NA NA CDDL (SS-02 and WVNSCO 1994, Table 3-2 (1990 data])
Sediment from drainage through 7.0E+OO 8.4E+01 NA NA 7.3E-02 7.4E-02 1.3E-01 CDDL (ST-31 , ST-38)
Sediment from Northeast Swamp 3.1E+01 3.0E+01 1.1E+OO 1.1 E+OO 4.3E-01 6.4E-01 1.3E+OO drainage (SNSWAMP)
Subsurface soil in CDDL (BH-27 (Cs- 7.3E-01 4.1E+OO NA NA NA NA NA 137 max at 2-4'], BH-25 [Sr-90 max at12-14'])
LEGEND: COOL= Construction and Demolition Debri s Landfill; NA= No analysis.
NOTE : (1) See Figures 4-6 and 4-7 for maps showing locations with radionuclide concentrations in excess of background.
Revision 2 4-41
WVDP PHASE 1 DECOMMISSIONING PLAN Sediment from drainage locations on WMA 4 also contained Sr-90 and Cs-137 at levels exceeding background . However, it also contained above-background levels of the alpha-emitting radionuclides U-233/234, U-238, Pu-238, Pu-239/240, and Am-241 . Maximum radionuclide ratios to Cs-137 were : Sr-90 (16 to 1), U-233/234 (1.4 to 1). U-238 (1 .3 to 1)
Pu-238 (0.057 to 1), Pu-239/240 (0.21to1), and Am -241 (0.22 to 1) .
The maximum Sr-90 to Cs -137 ratio in sediment was noted from drainage through WMA 4 north of the landfill. The north plateau groundwater plume surfaces near ST-38 where this sample was taken (see Figure 4-6). Maximum ratios for the remaining radionuclides were noted at the routine monitoring point SNSWAMP, which is located where drainage from WMA 4 leaves the site. Sediment (or soil, depending upon annual rainfall and drainage flow patterns) is collected at this location as part of the WVDP Environmental Monitoring Program . (See Appendix B for average and median radionuclide concentrations at the SN SWAMP location from 1995 through 2007 .)
The comparatively high Sr-90 to Cs-137 ratios observed for surface soil and sediment in WMA 4 reflect the presence of Sr-90 in the north plateau groundwater plume.
Both Cs -137 and Sr-90 concentrations exceeding background were noted in subsurface soil from WMA 4. Because the landfill located on WMA 4 was not used for radioactive waste disposal, it was not thought to be the origin of the radionuclides . Cs-137 in subsurface soil is most likely leached from the overlying surface soil (the concentration of Cs-137 at the two to four feet depth was roughly one-tenth of the concentration at the surface) . As seen in other areas, elevated levels of Cs-137 in surface soil may be attributable to airborne deposition (see Section 2) . The maximum ratio of Sr-90 to Cs-137 for subsurface soil was about 0.73 to 1. As with the surface soil and sediment media, the north plateau groundwater plume is thought to be the origin of Sr-90 in subsurface soil in WMA4.
WMA 5, Waste Storage Area Concentrations of radiological constituents measured at levels in excess of background in surface soil, sediment, and subsurface soil from WMA 5 are listed in Table 4-18. Cs-137 and Sr-90 concentrations exceeding background were found in surface soil and sediment.
Concentrations of the alpha-emitting radionuclides Pu-238, Pu-239/240, and Am -241 exceeding background were also ~ound, possibly attributable to residual activity from the old/new hardstand, on which contaminated vessels and equipment from the Process Building had been stored when NFS was operating . Historical site surveys have noted elevated gamma radiation readings and soil contamination in the area of the old/new hardstand (Marchetti , 1982) . Material from the hardstand was excavated and used to fill Lagoon 1 when it was closed in 1984 . (See Section 2.)
Maximum ratios to Cs-137 in soil and/or sediment were : Sr-90 (3 .3 to 1), Pu-238 (0.015 to 1), Pu-239/240 (0.096 to 1), and Am-241 (0.087 to 1) . The maximum ratios were all found in sediment from the North Swamp drainage point SNSW74A.
Revision 2 4-42
WVDP PHASE 1 DECOMMISSIONING PLAN No concentrations exceeding background of Cs-137 or alpha-emitting radionuclides were noted in subsurface soil samples from WMA 5. However, Sr-90 concentrations above background were found six to eight feet below-ground at a point between Lag Storage Addition 3 and Lag Storage Addition 4 and 22 to 24 feet below the surface at the southernmost point of WMA 5 near the Lag Storage Building.
Table 4-18. Above-Background Concentrations of Radionuclides in Surface Soil, Sediment, and Subsurface Soil at WMA 5 (1)
Maximum Concentration (pCi/g dry)
Location Pu-239/
Cs-137 Sr-90 Pu-238 Am-241 240 Surface soil on north plateau 2.0E+01 3.7E-01 NA NA NA near security fence (SS-01)
Surface soil near Remote-Handled Waste Facility 1.1E+01 8.2E-01 3.6E-02 1.6E-01 3.7E-01 location (BH-38)
Surface soil from footers for LSA 3 and LSA 4 (WVNSCO 2.8E+01 NA NA NA 9.1 E-01 1994, Table 3-15 [1990 data])
Surface soil from the Lag 7.8E-01 :SB kg :SB kg :SB kg :SB kg Storage Building (BH-32)
Sediment near old LSA 2 (ST-6.1 E+01 8.3E+OO :SB kg :SB kg 6.5E-02 37)
Sediment from north swamp 8.8E+OO 2.1E+OO :SB kg 1.9E-01 2.6E-01 drainage (SNSW74A)
Subsurface soil between LSA
- SB kg 2.8E+OO NA NA NA 3 and 4 (BH-29, 6-8' depth)
Subsurface soil by the lag storage building (BH-32, 22- :SB kg 5.8E-01 :SB kg :SB kg :SB kg 24' depth)
LEGEND: LSA =Lag Storage Addition. NA= No analysis. "SBkg" =Background was not exceeded .
NOTE : (1) See Figures 4-6 and 4-7 for maps showing locations with radionuclide concentrations in excess of background.
WMA 6, Central Project Premises Concentrations of radionuclides measured at levels in excess of background in surface soil, sediment, and subsurface soil from WMA 6 are listed in Table 4-19 . Cs-137 and Sr-90 were the only radionuclides found in concentrations exceeding background in surface soil and sediment from WMA 6. The highest concentrations of both Cs-137 and Sr-90 were found in surface soil collected near the Fuel Receiving and Storage Building .
The highest Sr-90 to Cs-137 ratio in surface soil (1.7 to 1) was also found in soil near the rail spur by the Fuel Receiving and Storage Building. The highest Sr-90 to Cs-137 ratio in sediment (0.59 to 1) was found in sediment from the south Demineralizer Sludge Pond .
Revision 2 4-43
WVDP PHASE 1 DECOMMISSIONING PLAN The highest radionuclide concentrations in surface soil and sediment were from the northern portion of WMA 6, closest to the Process Building . However, elevated concentrations were also found along the rail spur south of the Sewage Treatment Plant.
These elevated concentrations may be attributable to events in the 1960s and 1970s (e .g ..
increased radioactivity in treated effluents or possible line leaks [see further detail in Section 2.3.2)) .
Subsurface soil samples - one from near the Utility Room and one from near the Fuel Receiving and Storage Building - contained Cs-137, Sr-90, Pu-238, Pu-239/240, and Am -
241 concentrations exceeding background . The highest concentrations were found near the Fuel Receiving and Storage Building at a depth of 22 to 24 feet in the sand and gravel unit below the water table. (See Figure 4-8.) The maximum concentrations near the Utility Room were from 16 to 18 feet below the surface.
Ratios to Cs-137 for Pu -238, Pu -239/240, and Am-241 were similar for subsurface soil samples taken near the Utility Room and the Fuel Receiving and Storage Building (about 0.03 to 1, 0.04 to 1, and 0.2 to 1, respectively). However, the Sr-90 to Cs-137 ratios for each were strikingly different. Near the Utility Room, the ratio was about 1 to 1, but near the Fuel Receiving and Storage Building the ratio was 133 to 1, suggesting that the Fuel Receiving and Storage Building subsurface location was more central to the north plateau groundwater plume .
Sampling of subsurface soil by Geoprobe in 2008 south of the Fuel Receiving and Storage Area , close to 1993 sampling locations BH -17 and BH-19A, continued to show above-background concentrations of most radionuclides . See Figure 4- 7. As with WMA 1 and WMA 2, elevated ratios of Sr-90 to Cs-137 in the portion of WMA 6 lying between WMAs 1 and 2 (with a median of 17 4 to 1 and a maximum of 1115 to 1) reflected the influence of the north plateau groundwater plume. However, maximum concentrations of Cs-137 and Sr-90 in the subsurface saturated layer were lower than those observed in BH-17 and BH-19A in 1993.
Table 4-19. Above-Background Concentrations of Radionuclides in Surface Soil, Sediment, and Subsurface Soil From WMA 6(1)
Maximum ConcentratiQn (pCi/g dry)
Location U-233/ U-235/ Pu-239/
Cs-137 Sr-90 U-232 U-238 Pu-238 Am-241 234 236 240 Surface soil along 1.8E+OO 3.2E-01 NA NA NA NA NA NA NA rail spur south of STP (BH-23, SS-13)
Sediment along 2.1E+OO 1.3E-01 NA NA NA NA NA NA NA drainage by rail spur south of STP (ST-25)
- Revision 2 4-44
WVDP PHASE 1 DECOMMISSIONING PLAN
-Table 4-19. Above-Background Concentrations of Radionuclides in Surface Soil, 1
Sediment, and Subsurface Soil From WMA 6( )
Maximum Concentration (pCi/g dry)
Location U-233/ U-235/ Pu-239/
Cs-137 Sr-90 U-232 U-238 Pu-238 Am-241 234 236 240 Surface soil by FRS 1.6E+02 1.2E+01 NA NA NA NA NA NA NA (1994 sampling near rail spur)
Surface soil by 1.3E+01 1.4E+OO NA NA NA NA NA NA NA Cooling Tower (SS-10)
Surface soil by Old 1.9E+01 2.3E+OO NA NA NA NA NA NA NA Incinerator (WVNSCO 1994, Table 3-2 [1990 data])
Surface soil by Old 1.3E+01 9.3E-01 NA NA NA,. NA NA NA NA Warehouse (SS-09)
Sediment from 1.3E+01 7.?E-01 NA NA NA NA NA NA NA North Demineralizer Sludge Pond (WVNSCO 1994 Table 3-18 [1988 data], ST-35)
Sediment from 3.8E+01 3.5E-01 NA NA NA NA NA NA NA South Demineralizer Sludge Pond (WVNSCO 1994 Table 3-19 [1988 data], ST-36)
Subsurface soil 2.4E+OO 2.7E+OO 5Bkg 5Bkg 5Bkg 5Bkg 6.1E-02 9.7E-02 4.9E-01 near the Utility Room (BH-17, 14-16' depth)
Subsurface soil 4.3E+OO 5.7E+02 5Bkg 5Bkg 5Bkg 5Bkg 1.5E-01 2.0E-01 8.0E-01 near the FRS (BH-19A, 22-24' depth)
Subsurface soil 1.1E+OO 2.2E+02 9.1 E-02 1.3E+OO 3.5E-01 1.4E+OO 5Bkg 4.9E-02 1.4E-01 near rail spur south of the FRS (GP10208, 14-16' depth)
NOTE : (1) See Figure 4-5 for a map showing facilities in the northern portion of WMA 6. See Figures 4-6 and 4-7 for maps showing location s with radionuclide concentrations in excess of background .
LEGEND : NA = Not analyzed. "s;Bkg" = Background was not exceeded. FRS = Fu el Receiving and Storage Building, STP = Sewage Treatm ent Plant Revision 2 4-45
WVDP PHASE 1 DECOMMISSIONING PLAN WMA 7, NOA and Associated Facilities Concentrations of radiological constituents measured at levels in excess of background in surface soil and sediment from WMA 7 are listed in Table 4-20. Cs-137, Sr-90, and Am-241 were found in concentrations exceeding background in surface soil. Sediment samples
.collected near the Interceptor Trench conta_ined concentrations of Cs-137 , Sr-90, Pu-238 ,
and Am-241 in excess of background . Ratios of Sr-90 to Cs-137 in surface soil ranged from 0.11 to 1 to 8.2 to 1. The Sr-90 to Cs-137 ratio for sediment was about 3.7 to 1. Maximum ratios to Cs-137 for Pu -238, Pu -2 39/240, and Am-241 in surface soil and sediment were ,
respectively : 0.096 (sediment). 0.022 (surface soil), and 0.046 (sediment) . All were found near the Interceptor Trench.
No concentrations above background were found in boreholes of subsurface soil taken in 1993 at WMA 7. (Note that the two subsurface soil borings done at this location in 1993 were taken from the edges of the burial area, one upgradient of the buried waste and the other on the opposite side of the Interceptor Trench downgradient of the area .) However, analybical results from boxes and rolloffs ~illed with subsurface soil excavated during construction of ~e Interceptor Trench or from rionspeoific "special holes" contained Am-241 concentrabions well in excess of background. Ratios of Am-241 to Cs-137 ranged from 0.024 to 0.077 to 1. The excavated soil has been shipped offsite, however, results suggest that subsurface soil remaining in the NOA contains radionuclide concentrations exceeding background .
Table 4-20. Above-Background Concentrations of Radionuclides in Surface Soil ,
Sediment, and Subsurface Soil at WMA 7(1>
Maximum Concentration (pCi/g dry)
Location Pu-239/
Cs-137 Sr-90 Pu-238 Am-241 240 Surface soil by the NOA 4.7E+OO 3.3E+OO 8.SE -02 9.2E -02 1.SE-01 Interceptor Trench (SS-15, BH -
42)
Surface soil by the NOA 6.8E+01 7.7E+OO NA NA NA Hardstand (SS-20)
Surface soil at remainder of NOA 3.2E+OO 2.1 E+01 NA NA NA (1994 data from special sampling)
Sediment from drainage near 9.0E-01 3.3E+OO 8.6E-02 ::;Bkg 4.1E-02 Interceptor Trench (ST-23)
Subsurface soil excavated from 3.5E+01 NA NA NA 1.8E+OO Interceptor Trench or "special holes" (1997 sampling of excavated soil in boxes and roll offs)
NOTE: (1) See Figure s 4-6 and 4-7 for maps showing locations with radionuclide concentrations in excess of background . Not shown on the map, the Interceptor Trench borders the northeast and northwest boundaries of the NOA. Th e Trench was in stall ed in 1990 to intercept and collect leaching from the NOA. The NOA Hardstand (not shown on the map) was located at the easternmost point of WMA 7.
Revision 2 4-46
WVDP PHASE 1 DECOMMISSIONING PLAN WMA 9, Radwaste Treatment Drum Cell Area Data from only two surface soil samples were available for WMA 9. Although gross beta concentrations exceeded background for both, data for specific beta -emitting radionuclides did not. (See Figure 4-6.) No subsurface soil or sediment data were available for WMA 9.
WMA 10, Support and Services Area Concentrations of radiological con stituents measured at levels in excess of background in surface soil and sediment from WMA 10, the Support and Services Area, are listed in Table 4-21 . This area includes support facilities (e .g., administrative buildings, offices, parking lots, the Environmental Laboratory) that are not known to be radiologically contaminated. Note that only one surface soil sample shown on Figure 4-6 did not have concentrations exceeding background : SS-11 on the north plateau, located on the western side of the project premises in WMA 10.
Low-level concentrations of Cs-137 exceeding background were found in surface soil near support trailers close to the Process Building and in sediment from a drainage ditch south of the Environmental Laboratory. Elevated Cs-137 in surface soil is thought to be attributable to airborne releases . Elevated Cs-137 in the drainage ditch could be attributable to runoff from WMA 6 (i.e., possibly related to historical releases or leaks from the old Sewage Treatment Plant that released radionuclides to drainage by the railroad bed, as discussed in Section 2). Although gross alpha and gross beta concentrations slightly above background were noted for certain surface soil samples from WMA 10 (as shown on Figure 4-6), no other concentrations of specific radionuclides above background have been reported .
Table 4-21. Above-Background Concentrations of Radionuclides in Surface Soil and Sediment at WMA 10(1)
Maximum Concentration (pCi/g dry)
Location Cs-137 Surface soil by former Trailer City (1998 1.0E+OO special soil sampling)(2)
Sediment samples by drainage south of 1.7E-01 Environmental Laboratory (ST-26)
NOTE: (1) See Figure 4-6 for a map showing locations with radionuclid e concentrations in excess of background .
Not shown on maps, the former Trailer City was located directly opposite the western entrance to the Process Building. The Environmental Laboratory (shown, but not labeled, on Figure 4-6) is located immediately north of sampling point ST-26.
(2) A total of 15 samples were collected in 1998 near Trailer City. Two samples showed approximately 1.0 pCi/g Cs-137, with Cs-137 in the other samples less than this concentration.
WMA 12, Remainder of the Site Concentrations of radiological constituents measured at levels in excess of background in surface soil and sediment from WMA 12 are listed in Table 4-22 . Only the portion of WMA 12 within the project premises. which includes the onsite segments of Franks Creek and Erdman Brook, is addressed in this evaluation .
Revision 2 4-47
WVDP PHASE 1 DECOMMISSIONING PLAN Surface soil concentrations of
- both Cs-137 and Sr-90 were noted in excess of background in WMA 12 (see Figure 4-6). Cs-137 and Sr-90 exceeding background concentrations were also found in sediment samples from both Franks Creek and Erdman Brook, as well as in drainage downgradient of the demineralizer sludge ponds. Sediment samples collected along the lengths of both Franks Creek and Erdman Brook also contained alpha-emitting radionuclides at concentrations in excess of background, although the radionuclides varied in relationship to the stream segment.
In Erdman Brook downstream of drainage from the NOA (locations ST-22 and ST-21).
Am-241 and Pu-238 were observed in concentrations greater than background . Further downstream, at point ST-20, after the stream receives inflow from a drainage from WMA 2, Am-241 , Pu -238, and Pu-239/240 concentrations were all above background. At point ST-19, located downstream where the stream receives effluent from Lagoon 3, U-232 (in addition to the other radionuclides) was also found above background .
Similarly, sediment at the southernmost segments of Franks Creek (points ST-13 , ST-12, and ST-11) contained gross alpha concentrations in excess of background . However, at point ST-10, located downstream of its junction with Erdman Brook, concentrations of Am-241 , Pu-238, and Pu-239/240 were found in its sediment in excess of background .
Table 4-22. Above-Background Concentrations of Radionuclides in Surface Soil and Sediment at WMA 12(1l .
Maxim um Concentration (pCi/g)
Location Pu-239/
Cs-137 Sr-90 U-232 Pu-238 Am-241 240 Surface soil near borders 8.1E+OO 1.3E+OO NA NA NA NA with WMA 2 and WMA 6 (SS-08 [Cs-137). BH -16 [Sr-90])
Surface soil near eastern 1.6E+OO 4.4E+OO SB kg SB kg SB kg SB kg fence line (SS -07)
Sediment from drainage 6.0E+OO 8.SE-01 SB kg SB kg 7.3E-02 1.4E-01 downgradient of Demineralizer Sludge Ponds (ST-27)
Sediment from Erdman 3.5E+01 1.6E+OO 1.1E-01 2.SE-01 7.3E-02 1.4E-01 Brook (ST-19 [Cs-137, Sr-90, U-232). ST-20 [Pu-238, Pu-239/240], ST-22 [Am-241])
Sediment from Franks 1.0E+02 1.0E +01 1.4E-01 1.4E-01 1.1E-01 2.4E-01 Creek (ST-10 [Cs-137 only).
SNSP006)
NOTES : (1) See Figure 4-6 for a map showing locations with radionuclide concentrations in excess of background. The location of the Demineralizer Sludge Ponds is shown in Figure 4-5.
LEGEND : NA = No analysis. "SBkg" = Concentrations did not exceed background.
Revision 2 4-48
WVDP PHASE 1 DECOMMISSI ONING PLAN .
The highest concentrations of all radionuclides (except Pu-238, for which the maximum was found at point ST-20 on Erdman Brook) were observed in sediment from Franks Creek 16 at location SNSP006, where it flows off site at the security fence . As was found with sediment from Erdman Brook, sediment from Franks Creek collected downgradient of the controlled effluent water release point WNSP001 contained U-232 at concentrations exceeding background . (PermMed effluent water discharged from lagoon 3 through WNSP001 often contains small but measureable quantities of U-232 .) Summary statistics for radionuclide concentrations at SNSP006 are presented in Appendix B.
The highest ratio of Sr-90 to Cs-137 (about 3 to 1) in surface soil from WMA 12 was noted for one sample collected near the eastern edge of the fenced area . In sediment, the maximum ratios to Cs-137 for Sr-90 (0 .1 to 1), Pu-239/240 (0.012 to 1). and Am-241 (0.023 to 1) were all found downgradient of the Demineralizer Sludge Ponds . The highest ratios to Cs-137 of U-232 (0 .003 to 1) and U-238 (0.007 to 1) were found in sediment from Erdman Brook, immediately after the point where it receives Lagoon 3 effluent.
4.2.6 Environmental Radiation Levels As part of the WVDP Environmental Monitoring Program, since 1986 TLDs have been placed in the field to measure levels of integrated gamma radiation exposure. TLDs are placed :
(1) At background locations far from the Center, (2) At communities near the Center, (3) At a ring of perimeter locations around the Center, and (4) At onsite locations near process areas, waste storage areas, and waste burial locations .
Figure 4-9 shows the locations of onsite TLDs.
Note that not all areas on the project premises have environmental TLD monitoring locations, therefore, data are not available for these areas. Average results over the last ten years, in mR/quarter and in mR/h, are summarized in Table 4-23. Onsite results are presented by waste management area. For comparison, measurements from background are included .
Exposure measurements from the ring of TLDs around the perimeter of the Center and at the community locations are evaluated each year as part of preparing the Annual Site Environmental Report. Values from offsite TLDs have consistently been indistinguishable from background .
16 In 1990, a sample from a hot spot in Erdman Brook that measured 3000 µR/h during the ground-l evel survey showed 0.01 µCi/g (10,000 pCi/g) Cs-137 . (This was a screening analysis that may have been performed on a wet sample; it was not validated .) This area of localized contamination was described as about six inches by six inches located one meter from the edge of the water. Limited investigation indicated that the contamination extended more than seven inches below the streambed surface. (Passuite and Monsalve-Jones 1993, App endix C)
Revision 2 4-49
WVDP PHASE 1 DECOMMISSIONING PLAN Results from all onsite TLDs, with the single exception of DNTLD27 located on the eastern border of the security-fenced area, were in excess of background levels. Note that exposure levels in the Table 4-23 may not be indicative of radionuclides in soil, but of radiation from the wastes being processed and/or stored nearby.
The onsite monitoring point with the highest dose readings was location DNTLD24 on the north plateau (Figure 4-9) . Sealed containers of radioactive components and debris from the plant decontamination work are stored nearby in the Chemical Process Cell Waste Storage Area . Exposure rates at this location have been generally decreasing over time beca use the radioactivity in the materials stored nearby is decaying . This storage area is well within the Center boundary, just inside the WVDP fenced area, and is not accessible by the public .
The maximum quarterly exposure level (1298 mR/qtr [0.59 mR/hr)) was noted at DNTLD35, near the rail spur by the Drum Cell in the second quarter of 2007 . This high reading was associated with waste storage and with staging and shipping drums of cement-stabilized waste from the Drum Cell. All remaining drums were shipped from the Drum Cell in 2007 , and in the fourth quarter of 2007 the exposure level at DNTLD35 had dropped to 23 mR/qtr (0.011 mR/hr) .
Revision 2 4-50
WVDP PHASE 1 D ECOMMISSIONING PLAN N
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+ Qn.Srte Them-otuminescent DoSlmeter c::J waste Management Areas
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__.._ VWOP Rallspu-250 750 1,000 Feet C3 Welland*
Figure 4-9. Onsite Environmental TLD Locations Revision 2 4-51
WV D P PHASE 1 DECOMMISSIONING P LAN Table 4-23. Environmental Radiation Levels on the WVDP Site (1998-2007 data)
Average Average Maximum Maximum t1lExceeds TLD (s) Location mR/qtr mR/h mR/qtr mR/h Background?
DNTLD40 Waste Tank Farm (WMA 3) 119 0.054 268 0.122 Yes DNTLD26 Construction and Demolition 23 0.011 30 0.014 Yes Debris Landfill fence line (WMA 4)
DNTLD24 Chemical Process Cell Waste 523 0.239 717 0.327 Yes Storage Area fence line (WMA 5)
DNTLD25 Quarry Creek, between 23 0.011 31 0.014 Yes security fence and public road (WMA5)
DNTLD30 Northwest parking lot, near 23 0.010 32 0.015 Yes public road (WMA 10)
DNTLD39 On fence between parking lot 49 0.022 70 0.032 Yes and Process Building (WMA 10)
DNTLD38 Nurse's office across Process 34 0.015 55 0.025 Yes Building (WMA 10)
DNTLD29 On fence near Environmental 22 0.010 29 0.013 Yes Laboratory (WMA 10)
DNTLD28 Southwestern corner of Project 22 0.010 38 0.018 Yes Premises (WMA 10)
DNTLD35 t2lNear rail spur by Drum Cell 109 0.050 1298 0.592 Yes (WMA9)
DNTLD36 (2lDrum Cell north fence (WMA 61 0.028 458 0.209 Yes 9)
DNTLD43 Drum Cell northeastern fence 31 0.014 69 0.031 Yes (WMA9)
DNTLD33 Drum Cell southeastern corner 32 0.014 54 0.025 Yes (WMA9)
DNTLD19 Western fence line near waste 22 0.010 39 0.018 Yes burial areas (WMA 12)
DNTLD27 Eastern fence line farthest from 20 0.009 27 0.012 No process and waste storage areas (WMA 12)
Background Four background locations 19 0.009 35 0.016 NA (map in Appendix B)
NOTE : (1) Data sets from each location were compa red with background data sets using one-way analysis of variance (see Appendix B) .
(2) Exposure measurements near the Drum Cell have been elevated in the last several years becau se the area is being used as a storage area for vessels removed from the Process Building and for staging waste for shipping. Waste drum s formerly stored in the Drum Cell itse lf were removed in 2007 .
Revision 2 4-52
WVDP PHASE 1 DECOMMISSIONING PLAN As summarized in WVNSCO 1994, two aerial radiation surveys of the WNYNSC in 1969 and 1979 identified above-background gamma radiation extending from the Process Building in a northwest direction along Buttermilk Creek (1969) and in a prong extending westward offsite across Rock Springs Road (1979). Cs-137 was determined to be the source of the gamma activity. (See Section 2.)
Soil sampling by NYSDEC in 1971 and by WVNSCO in 1982 determined that Cs-137 activity was greater in soil northwest of the Process Building and that activity was greatest at the soil surface and decreased with depth (WVNSCO 1994) . Activity in the cesium prong is attributed to airborne releases from a filter blow-out in 1968, as indicated in Section 2. Elevated radionuclide concentrations in the Buttermilk Creek drainage are attributed to routine permitted radioactive liquid releases .
Posted Radiation Areas At the WVDP Site, radiation areas are posted if exposure can exceed 5 mrem/hr at 30 centimeters (WVNSCO 2006) . Posted radiological control areas on the project premises are shown in Figure 4-10 . Posted radiation levels are generally indicative of surface and/or near-surface contamination , storage of radioactive waste, and proximity to radiological process areas. Posted areas are delineated in accordance with 10 CFR 835, Occupational Radiation Protection.
Revision 2 4-53
WV DP P HASE 1 D ECOMMISSIONING P LAN r _...-** -** *<. . .._
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Legend Radiation ftreas:
/lrly area V\here radiation levels cou d result
~ '}'?~ Radiological Control Areas in an individual recei'¥ing > 0 .005 rem in 1 hr at 30 an .
C::J Waste Management Areas Corrt am ination .Areas:
See 10 CFR 835 .Appendix D Figure 4-10. WVDP Radiological Control Areas. (Facilities with rad iologica l controlled areas are outlined in black. Radiological Control Areas are current as of June 2008. )
Revision 2 4-54
WVDP PHASE 1 DECOMMISSIONING PLAN 4.2.7 Radiological Status of Onsite Surface Water The WVDP Environmental Monitoring Program routinely collects surface water samples from the following locations on the project premises:
(1) Two penmitted effluent discharges (releases from Lagoon 3 through the weir at point WNSP001 and from the Sanitary Waste Treatment Facility at point WNSP007) ;
(2) Two drainages where water from the North Swamp and the Northeast Swamp leave the site (points WNSW74A and WNSWAMP, respectively) ;
(3) Facility cooling water from the Cooling Tower (WNCOOLW);
(4) Two drainage ditches (facility drainage [point WNSP005) and NOA surface drainage [point WNNDADR)) ; and (5) Three locations on two streams (point WNERB53 on Erdman Brook, point WNFRC67 on Franks Creek, and point WNSP006 where Franks Creek leaves the project premises at the security fence) .
Figure 4-11 shows the location of these routine surface water monitoring locations and indicates those with gross alpha (or alpha-emitting radionuclide) concentrations and gross beta (or beta/gamma-emitting radionuclide) concentrations in excess of background. All surface water locations had at least one constituent exceeding background (i .e .. no non-impacted locations were noted).
Table 4-24 summarizes median, average, and maximum concentrations of those radionuclides observed to exceed background in surface water over the ten-year period 1998-2007. (For a complete summary of radionuclide concentrations in surface water, Including those not detected above background, see Table B-13 of Appendix B.) Note that concentrations of the beta-emitting radionuclide Sr-90 exceeding background were observed in surface water throughout the project premises. (See Appendix B for comparable summary statistics for each radionuclide in surface water from background locations .) The highest Sr-90 concentrations were observed at location WNSWAMP, which is downstream of the point where the leading edge of the north plateau groundwater plume surfaces.
The full suite of radionuclides monitored in surface water was detected at above-background concentrations at the permitted Lagoon 3 discharge point WNSP001 . Tritium was detected downstream of the Low-Level Waste Treatment Facility (points WNSP001 and WNSP006), at the Northeast Swamp Discharge Point (WNSWAMP), at a point immediately downstream of the NOA on the south plateau (WNNDADR), and in Erdman Brook and Franks Creek on the south plateau (locations WNERB53 and WNFRC67, respectively) .
Alpha-emitting radionuclides at concentrations exceeding background were noted only in surface water from the north plateau, primarily at locations downstream of the Low-Level Waste Treatment Facility discharge, but also at the North (WNSW74A) and Northeast Swamp (WNSWAMP) permitted discharge points.
Revi sion 2 4-55
WVDP PHAS E 1 DECOMMISSIONI NG PLAN
)
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0 legend Surface Water Sampling Locations
- Gross Alpha or Alpha-Emittlng Radlonucndes in Excess or Background Gross Beta or Beta-Emitting Radlonuclides in Excess of Background Both Alpha and Beta Emitters in Excess of Background
- No Radiological Constituents in Excess of Background 240 0 Figure 4-11. Surface Water Locations with Radionuclide Concentrations in Excess of
Background
Revision 2 4-56
WVDP PHASE 1 DECOMMISSIONING PLAN Table 4-24. Radionuclide Concentrations (pCi/L)t1J in Excess of Background in Surface Water(Z)
Average Location Median Maximum Result +/- Uncertainty ILagoon 3 discharge wei r (WNSP00 1), WMA 2 I H-3 2.5E +03 2.8E +03 +/- 1.4E+02 7.2E +03 C-14 < 2.8E +01 1.4E+01 +/- 2.2E+01 4.8E +01 Sr-90 9.9E +01 1.2E +02 +/- 7.4E+OO 3.2E +02 Tc-99 6.5E+01 7.9E +01 +/- 4.8E+01 3.4E+03 1- 129 2.1 E+OO 2.4E+OO +/- 1.5E+OO 1.0E+01 Cs-137 6.1 E+01 7.6E+01 +/- 1.9E+01 3.3E+02 U-232 8.0E +OO 9.0E +OO +/- 9.9E-01 2.1E+01 U-233/234 5.0E+OO 5.5E+OO +/- 6.2E-01 1.4E+01 U-235/236 2.6E-01 2.8E-01 +/- 1.2E-01 5.8E-01 U-238 3.8E +OO 3.8E +OO +/- 4.9E-01 7.6E +OO Pu-238 6.5E-02 1.5E -01 +/- 6 .8E -02 1.6E +OO Pu -239/240 5.2E-02 1.3E-01 +/- 6.2E -02 1.4E+OO Am- 241 6.8E-02 1.2E-01 +/- 6.0E-02 9.7E -01 INortheast swamp drainage (WNSWAMP), WMA 4 I H-3 1.1 E+02 1.1 E+02 +/- 8 .2E+01 5.2E+02 Sr-90 1.5E+03 1.7E+03 +/- 3.1 E+01 5.2E+0 3 U-233/234 1.7E-01 2.0E-01 +/- 1.4E-01 9.3E -01 U-238 1.0E-01 1.2E-01 +/- 1.1E-01 7.2E-01 INorth swamp drainage (WNSW74A), WMA 5 I Sr- 90 5.5E +OO 5.5E+OO +/- 1.8E+OO 1.2E+0 1 U-23 3/234 1.5E-01 1.6E-01 +/- 8.4 E-02 3.5E-0 1 U- 238 1.0E-01 1.0E-01 +/- 6.6E-02 2.0E -01 ISanitary waste discharge (WNSP007) , WMA 6 I I Sr- 90 I - 3.1 E+OO I 3.4E+OO +/- 1.9E +OO I 1.2E+0 1 I IFranks Creek at security fence (WNSP006), WMA 12 I H-3 < 8.5E +01 1.4E+02 +/- 8 .3E+01 2.2E +03 Sr-90 1.9E+01 2.0E+01 +/- 3.0E+OO 5.0E+01 Tc-99 < 2.1 E+OO 3.3E+OO +/- 2.1 E+OO 5.2E+01 Cs- 137 < 8.0E+OO 6.3E+OO +/- 9.5E+OO 7.3E +01 U-232 3.2E -01 3.2E-01 +/- 1.3E-01 7.5E-01 U-233/234 3.7E -01 3.7E-01 +/- 1.3E-01 6.9E-01 U-238 2.5E-01 2.8E-01 +/- 1.1E-01 7.4E-01 Pu-238 < 3.4E-02 2.1E-02 +/- 3.4E-02 1.4E-01 Revision 2 4-57
WVDP PHASE 1 DECOMMISSIONING PLAN Table 4-24. Radionuclide Concentrations (pCi/L)l1J in Excess of Background in Surface Water(2l Average Location Median Maximum Result +/- Uncertainty Facility yard drainage (WNSPOOS), WMA 12 H-3 < 8.3E+01 3.8E +01 +/- 8.2E+01 1.2E+03 Sr-90 9.6E+01 1.0E +02 +/- 6.5E+OO 2.0E+02 ge between NOA and SDA (WNNDADR), WMA 12 H-3 1.0E+03 1.1E+03 +/- 1.0E+02 4.0E+03 Sr-90 8.5E+01 8.4E +01 +/- 5.4E+OO 1.2E+02 Erdman Brook north of disposal areas (WNERB53), WMA 12 H-3 < 8.3E+01 3.9E +01 +/- 8.0E+01 4.9E+02 Sr-90 8.2E+OO 8.0E +OO +/- 2.0E+OO 9.9E+OO I Franks Creek East of SDA (WNFRC67), WMA 12. I I H-3 I < 8.3E+01 I 3.1E+01 +/- 8.1 E+01 I 3.5E+02 I NOTES: (1) 1 pCi/L = 3.7E-02 Bq/L (2) Refer to Table 4-11 for median and maximum background values and to Appendix B for summary stati stics of background radionucl ide concentrations in surface water.
4.2.8 Radiological Status of Groundwater NOTE The information provided below does not include data from characterization measurements for Sr-90 in subsurface soil and groundwater collected during a 2008 -
2009 investigation to support design of mitigation measures for the leading edge of the north plateau groundwater plume. However, results from this investigation were used to redefine the leading edge of the plume as shown in Figure 4-14. Complete results of this characterization can be found in report WVDP-500 (WVES 2009b) .
Groundwater at the WVDP is routinely monitored in accordance with the WVDP Groundwater Monitoring Program . Although the primary focus of the program is on nonradiological constituents, all wells are monitored for radiological indicator parameters (gross alpha , gross beta, and H-3) . Several wells, especially those impacted by the north plateau groundwater plume, are sampled for Sr-90. Select wells are monitored for a full suite of radionuclides . Table 4-25 lists routine groundwater monitoring locations at which radiological concentrations were found at levels exceeding background. Medians, averages, and maximum concentrations (in pCi/L) are presented for each .
For groundwater (unlike the other environmental media discussed in this section).
gross alpha and gross beta concentrations exceeding background are presented . This is because limited radionuclide data are available for routinely mo.nitored groundwater locations, and gross alpha and gross beta measurements, taken at all wells, may indicate Revision 2 4-58
WVDP PHAS E 1 D ECOMMISS IONING PLAN the presence of other alpha- or beta -emitting radionuclides . For instance, gross beta measurements are used as a surrogate measurement for Sr-90 at monitoring points where the Sr-90-to-gross beta ratio has been determined to be approximately 0.5 to 1.
Locations at which gross alpha (or alpha-emitting radionuclide) concentrations and/or gross beta (or beta-emitting radionuclide , including H-3) concentrations exceeded background are shown on Figure 4-12 . Locations at which no radiolog ical constituents were found to exceed background are also shown. For a comp lete summary of radionuclide data from both impacted and non-impacted routine groundwater monitoring locations, see Appendix B, Tabl e B-14. A li sting of supplementary information for each point (e.g., geographical coordinates. well construction, screened interval , geologic unit) is provided in Appendix B, Table B-15 .
Table 4-25. Routine Groundwater Monitoring Locations With Radionuclide Concentrations (pCi/L)!1l in Excess of Background '2l Monitoring Average WMA Constituent Median Maximum Point Result +/- Uncertainty WMA1 WP-A Gross beta 2.4E+01 3.1E+01 +/- 4.6E+OO 5.4E+01 H-3 1.2E+04 1.1 E+04 +/- 6.2E+02 1.3E+04 WMA2 WP-C Gross beta 2.4E+01 4.2E +01 +/- 5.5E +OO 1.2E+02 H-3 4.9E+04 4.7E+04 +/- 1.6E+03 6.6E+04 WP-H Gross alpha 6.1E+OO 7.9E+01 +/- 2.3E +01 7.4E+02 Gross beta 7.0E +03 7.2E+03 +/- 1.9E+02 1.2E+04 H-3 3.0E+03 3.4E+03 +/- 5.0E+02 7.4E+03 WNW0103 Gross beta 1.4E+02 1.8E +02 +/- 1.9E +01 5.5E +02 WNW0104 Gross beta 5.9E +04 5.6E+04 +/- 1.6E +03 1.0E+05 H-3 3.7E+02 3.9E+02 +/- 8.6E+01 7.5E+02 WNW0105 Gross beta 3.9E +04 3.3E +04 +/- 1.5E +03 1.0E+05 H-3 3.6E+02 3.7E+02 +/- 9.1E+01 7.1E+02 WNW0106 Gross beta 1.6E +01 8.2E+01 +/- 8.0E+OO 5.8E+02 H-3 9.6E +02 1.0E +03 +/- 1.0E+02 1.8E+03 WNW0107 Gross beta 7.0E+OO 8.2E+OO +/- 2.6E+OO 2.2E+01 H-3 3.7E +02 4.8E+02 +/- 9.0E+01 9.9E+02 WNW0108 Gross alpha 1.6E +OO 1.5E +OO +/- 1.5E +OO 4.3E+OO H-3 1.2E+02 1.1 E+02 +/- 8.4E+01 2.5E +02 WNW0110 H-3 1.3E+03 1.3E+03 +/- 1.1 E+02 1.7E+03 WNW0111 Gross alpha <4.4E+OO 3.2E +OO +/- 5.1E+OO 1.0E+01 Gross beta 5.6E +03 5.9E+03 +/- 1.4E+02 1.2E+04 H-3 2.0E+02 2.3E +02 +/- 8.4E+01 8.0E+02 WNW0116 Gross beta 8.7E +02 2.0E+03 +/- 1.6E +02 9.5E+03 Revi sion 2 4-59
WVDP PHASE 1 D EC OMMISSIONING PLAN Ta ble 4-25. Routine Groundwater Monitoring Locations With Radionuclide Concentrations (pCi/L)( 1) in Excess of Background(2)
Monitoring Average WMA Constituent Median Maximum Point Result +/- Uncertainty wMA2 H-3 1.7E +02 1.9E +02 +/- 8.2E+01 4.7E +02 WNW020 5 Gross beta 1.6E +01 1.7E +01 +/- 8. 4E +OO 4.1E +01 WNW0408 Gross beta 4.0E +05 4.0E +05 +/- 3.0E +03 6.3E+05 H-3 1.5E+02 1.9E+02 +/- 1.1 E+02 2.2E+03 Sr-90 1.5E+05 1.5E +05 +/- 1.7E +02 2.5E+05 Tc-99 1.6E +01 1.7E +01 +/- 3.3E +OO 2.5E+01 U-233/234 4.5E -01 5.3E-01 +/- 2.2E -01 1.3E+OO U-23 8 2.9E -01 3.1 E-01 +/- 1.6E-0 1 4.8E -01 WNW0501 Gross beta 1.9E +05 1.9E +05 +/- 2.6E +03 3.2 E+05 H-3 1.4E+02 1.2E+02 +/- 8.4E +01 3.2E +02 Sr-90 9.2E +04 9.3E+04 +/- 2.4E+02 1.5E +05 WNW0502 Gross beta 1.7E +05 1.6E +05 +/- 2.8E+03 2.3E +05 H-3 1.3E +02 1.4E+02 +/- 8.4E+01 5.0E +02 Sr-90 8.4E +04 8.3E +04 +/- 2.1E+02 1.2E+05 WNW8603 Gross beta 5.7E +04 4.8E+04 +/- 1.2E+03 9.0E +04 H-3 3.4E+02 3.4E +02 +/- 8.8E +01 5.8E +02 WNW8604 Gross beta 4.1 E+04 4.6E +04 +/- 1.1 E+03 1.0E +05 H-3 3.5E +02 3.8E +02 +/- 8.4E+01 6.4E +02 WNW8605 Gross alpha 9.1E+OO 8.5E +OO +/- 7.7E+OO 2.1E+01 Gross beta 1.1 E+04 1.1 E+04 +/- 1.7E +02 1.6E +04 H-3 3.7E +02 4.2E +02 +/- 8.7E +01 1.3E +03 wMA3 WNW8609 Gross beta 1.5E +03 1.4E+03 +/- 4.2 E+01 2.3E +03 H-3 4.5E +02 4.7E +02 +/- 9.1E+01 7.9E +02 Sr-90 8.0E +02 7.2E +02 +/- 2.1 E+01 1.1 E+03 wMA4 WNW0801 Gross beta 8.0E +03 8.6E +03 +/- 2.7E +02 1.5E+04 H-3 1.5E +02 1.6E +02 +/- 8.2E +01 3.8E +02 Sr-90 4.1E+03 4.3E +03 +/- 4.7E+01 8.0E+03 WNW0802 Gross beta 9.9E +OO 3.5E +01 +/- 5.1E+OO 2.8E+02 H-3 <1.1E+02 9.0E +01 +/- 8.0E+01 4.2E +02 WNW0803 Gross beta 1.5E +01 1.5 E+01 +/- 4. 7E +OO 2.5E+01 H-3 1.8E +02 1.6E +02 +/- 8.5E +01 3.4E +02 WNW0804 Gross beta 2.6E +02 2.9E +02 +/- 1.1E+01 6.9E +02 H-3 1.2E +02 1.1 E+02 +/- 8.0E +01 3.6E +02 WNW8612 H-3 4.2E +02 4.3E+02 +/- 8.9E+01 8.5E +02 lwMA5 I WNW0406 I Gross beta I 7.4E +OO 18.1E+OO +/- 3.5E +OO I 1.7 E+01 I Revi sion 2 4-60
WVOP PHASE 1 DECOMMISSIONING PLAN Table 4-25. Routine Groundwater Monitoring Locations With Radionuclide Concentrations (pCi/L)! 1 l in Excess of Background!2 l Monitoring Average WMA Constituent Median Maximum Point Result +/- Uncertainty H-3 1.2E +02 1.1 E+02 +/- 8.4E +01 4.4E +02 Tc-99 2.2E+OO 2.5E +OO +/- 1.9E +OO 8.5E +OO WNW0409 Gross alpha <1.0E +OO 9.4E -0 1 +/- 9. 9 E- 01 2.3E +OO WNW060 2A Gross beta 1.2E +01 1.3E +01 +/- 2.9E +OO 3.5E +01 H-3 2.2E +02 2.2E +02 +/- 8.9E +01 4.9E +02 WNW0604 Gross beta 6.1E +OO 6.3E+OO +/- 3.0E +OO 1.3E+01 WNW0605 Gross beta 4.8E +01 5.1 E+01 +/- 4.0E +OO 8.8E +01 WNW0704 Gross beta 8.0E +OO 8 .2E +OO +/- 3.0E +OO 1.3E +01 WNW8607 Gross beta 2.6E +01 2.7E +01 +/- 5.3E +OO 7.6E +01 WNW1304 U-233/234 2.7E-01 2.9E-01 +/- 1.3E-01 5.6E -01 U-23 8 1.9E-01 2.2E-01 +/- 1.0E -01 5.8E -01 WMA7 WNW0902 Gross alpha 1.5E +OO 1.3E +OO +/- 1.3E +OO 5.4E +OO WNW0909 Gross beta 3.7E +02 3.7E +02 +/- 1.4E+01 6.4E+02 H-3 8.2E +02 1.5E+03 +/- 1.2E+02 3.9E +03 Sr-90 1.9E +02 1.8E +02 +/- 8.3E +OO 2.2E +02 Tc-99 <1.9E +OO 1.3E+OO +/- 1.8E +OO 5.0E +OO 1-129 6.2E +OO 6.3E+OO +/- 1.9E +OO 9.7E +OO U-233/234 6.0E-01 7.4E-01 +/- 2.4E -01 1.3E +OO U-238 4.7E-01 5.4E -01 +/- 2.0E-01 1.0E +OO WNW0910 Gross alpha <2.5E +OO 1.9E +OO +/- 2.3E +OO 3.4E +OO Gross beta 3.8E +01 1.5E+02 +/- 8.5E +01 1.5E +03 WNNDATR Gross alpha 2.2E +OO 2.1 E+OO +/- 2.1E +OO 1.1 E+01 Gross beta 1.5E +02 1.8E +02 +/- 8.4E +OO 5.5E +02 H-3 3.6E +03 5.0E +03 +/- 2.3E+02 2.0E +04 Sr-90 5.8E +01 7.8E +01 +/- 5.5E +OO 2.8E +02 1-129 <9.1E-01 8.4E-01 +/- 9.4E -01 7.0E +OO U-233/234 1.7E +OO 1.5E+OO +/- 2.8E-01 2.1 E+OO U- 235/23 6 1.1E -01 1.4 E-01 +/- 9 .5E -02 3.0E -01 U-238 1.3E +OO 1.2E +OO +/- 2.5E-01 1.7E +OO I WMA9 I WNW1006 I Gross alpha I <5.1E+OO 14 .2E +OO +/- 5.5E +OO I 1.0E +01 I
NOTE S: (1) 1 pCi/L = 3. 7E -02 Bq/L (2) Refer to Tab le 4-11 for median and maximum background values and to Appendix B for summary stati sti cs of background radionuclide concentrations in groundwater (Table B-7) and at non-impacted groundwater monitoring locations (Tabl e B-14). Data sets from each loca tion were compared with backgro und data sets using the nonparametric Mann-Whitney "U" test, as descri bed in Appendix B, section 4.3.
Revi sion 2 4-61
WVDP PHASE 1 DECOMMISSIONING PLAN As shown in Figure 4-12, elevated gross beta concentrations are evident in groundwater northeast of the Process Building (WVNSCO and URS 2005) . The beta activity is primarily found in the surficial sand and gravel unit, and the general direction of flow in this unit is to the northeast. Elevated gross beta concentrations are largely attributed to Sr-90 in the north plateau plume. While concentrations of gross alpha or alpha-emitting radionuclides exceeding background were found at only a few locations, the locations were associated with (or downgradient of) historical waste processing or waste burial activities (i.e., WMAs 1, 2, and 7) .
In December 1993, elevated gross beta concentrations were detected in surface water at a former sampling location near the edge of the north plateau . This discovery initiated a subsurface groundwater and soil Geoprobe investigation in 1994 (Carpenter and Hemann 1995) . Two additional Geoprobe investigations were conducted in 1997 (Hemann and Fallon 1998) and 1998 (Hemann and Steiner 1999) .
Groundwater was collected in 2008 in accordance with a sampling and analysis plan (Michalczak 2007) for a Geoprobe characterization of the north plateau. Data from this sampling program have been included in the tables and figures for this section .
A listing of the Geoprobe locations, sample depths, and geologic units from which the groundwater was sampled is provided in Appendix B, Table B-16. (NOTE : For completeness, Appendix B, Table B-17, provides a listing of groundwater points - in addition to the routine groundwater monitoring and Geoprobe locations included in this evaluation - that have been sampled over the years. Table B-17 presents information on the locations and depths of these points, and summarizes the reasons that the points were not included in the current evaluation [dry wells, wells dropped from program, unvalidated data , located in areas outside the scope of the Phase 1 DP, etc .].)
The principal source of the north plateau groundwater plume is believed to be a release of radioactively contaminated acid from the NFS acid recovery system in the 1960s when NFS was reprocessing fuel, during 10 CFR Part 50 licensed activities. A detailed description of the release is provided in Section 2, subsection 2.3.1. See also Table 2-15 for an estimate of radionuclide activity from this release expected to remain in the plume in 2011 .
Revision 2 4-62
WVDP PHASE 1 D ECOMMISSIONING PLAN
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in Excess of Background No Radldoglcal ConslWuents In Excess C>f Background Figure 4-12 . Routine Groundwater Monitoring Locations with Radionuclide Concentrations in Excess of Background Revision 2 4-6 3
WVDP PHAS E 1 D ECOMMISSIONING PLAN The Geoprobe investigation results were used to estimate the extent of the north plateau groundwater plume beneath and downgradient of the Process Building . As part of the Geoprobe investigations, a more extensive suite of radionuclides was analyzed in groundwater than was done for routine monitoring . Because the Geoprobe groundwater samples differed from those taken from routine monitoring locations in that Geoprobe samples may have been taken from several depths (and even from different geologic units) at a single location, the sample results were not directly comparable and have not been presented in the same table . However, results from the Geoprobe investigations provide supplemental information about the presence of radionuclides in groundwater on the north plateau .
Geoprobe locations at which concentrations of alpha-emitting radionuc lides or beta/gamma-emitting radionuclides , including H-3, exceeded background are shown on Figure 4-13. The maximum measured radionuclide concentration s are summarized by WMA in Table 4-26 . (Since radionuclide data were available for these sampling locations, gross alpha and gross beta data , which could be affected by naturally occurring radionuclides, were not included in Table 4-26 or Figure 4-13) .
As can be seen in Figure 4-13, concentrations of beta/gamma -emitting radionuclides exceeding background are evident at most locations downgradient of the Process Building .
Most non-impacted points were noted in WMA 5 northwest of the north plateau groundwater plume . Alpha-emitting radionuclide concentrations exceeding background were found immediately downgradient of the Process Building and downgradient of the Interceptors.
Table 4-26. Maximum Above-Background Radionuclide Concentrations (pCi/L) at Groundwater Geoprobe Points by WMA, Location, and Depthn1 WMA Point Constituent Maximum Point Constituent Maximum WMA1 GP8098 (22-24') H-3 6.4E+-04 GP2908 (17-19') U-232 1.0E+-00 GP29 (27-29') C-14 2.3E+-03 GP2908 (17-19') U-233/234 1.1E+-01 GP30 (18-20') Sr-90 1.2E+-06 GP2908 (17-19') U-235/236 4.6E-01 GP72 (30-32') Tc-99 1.2E+-04 GP2908 (17-19') U-238 1.2E+-01 GP29 (21-23') 1-129 3.0E+-01 GP7608 (20-22') Pu-239/240 4.5E-01 GP7608 (20-22') Cs-137 1.2E+-02 GP76 (27-29') Am-241 4.7E-01 WMA2 GP47 (11-13') H-3 3.4E+-04 GP44 (14-16') U-233/234 3.7E+-01 GP66 (30-32') C-14 4.0E+-02 GP44 (14-16') U-235/236 6.2E-01 GP8298 (20-24') Sr-90 2.8E+-05 GP60 (1 2-14') U-238 1.5E+-01 GP68 (25-27') Tc-99 5.8E+-01 GP59 (17-19') Pu-238 4.5E+-OO GP47 (11-13') 1-129 8.2E+-01 GP59 (17-19') Pu-239/240 7.9E+{)0 GP46 (12-14') Cs-137 1.5E+-02 GP59 (17-19') Am-241 5.9E+{)0 GP44 (14-16') U-232 7.8E+-01 - - -
WMA3 GP20 (15-17') H-3 1.5E+-03 GP20 (15-17') 1-129 2.5E+-OO GP20 (15-1 7') Sr-90 5.2E+-01 - - -
I WMA4 I GP32A (5-7') I H-3 I 1.3E+-03 I GP8998 (16-18') I Sr-90 I 6.5E+-03 I WMA5 GP43 (12-14') H-3 2.0E+-04 GP53 (14-16') Tc-99 8.0E+-01 WMA5 GP40 (13-15') Sr-90 3.8E+-03 GP43 (12-14') 1-129 4.6E+-OO Revision 2 4-64
WVDP PHASE 1 DECOMMISSION ING PLAN Table 4-26. Maxim um Above-Background Radionuclide Concentrations (pCi/L) at Groundwater Geoprobe Points by WMA, Location, and Depth<1l WMA Point Constituent Maximum Point Constituent Maximum WMA6 GP70 (26-28') H-3 6.8E+-03 GP70 (21-23') Tc-99 3.1E+-01 GP70 (16-18') C-14 1.4E+-02 GP70 (21-28') 1-129 1.1E+-01 GP70 (16-18') Sr-90 2.8E+-04 - - -
WMA12 GP48 (7-9') H-3 1.5E+-03 GP50 (8-1O') U-238 7.2E-01 GP50 (8-10') Sr-90 1.3E+-01 - - -
. NOTE: (1) Points ending with "9 7, " "98," or "08" were collected in 1997, 1998, or 2008, respectively. The remaining points were co llected in 1994. Sample results were compared with average background values as described in Appendix B, section 4.2.
The north plateau plume, as delineated by the 1,000 pCi/L gross beta isopleth, was approximately 300 feet wide and 800 feet long in 1994. By 2002, the plume area had expanded to approximately 350 feet by 1050 feet, and by early 2009 to about 600 feet (at its widest point near the leading edge) by 1400 feet (WVES and URS 2009). See Figure 4-
- 14. Additional data from investigations performed in recent years have better defined the extent of the plume.
The highest gross beta concentrations in groundwater and soil were found near the southeast corner of the Process Building. In the 1994 study, the maximum concentration in groundwater was 3.6E+06 pCi/L, and the maximum concentration in subsurface soil was 2.4E+04 pCi/g . Sr-90 and its progeny, Y-90, were determined to be the isotopes responsible for most of the elevated gross beta activity (WVNSCO and URS 2007).
As a result of recommendations from a 1997 external review of WVDP response actions on the north plateau, more attention was given in 1998 to the core area of the plume, determined to be beneath and immediately downgradient of the Process Building .
Results from the 1998 investigation were presented in a summary report (Hemann and Steiner 1999) that compared groundwater and soil sampling data with the 1994 data .
Concentrations detected in 1998 samples were generally lower than those in the 1994 samples due to radioactive decay and continuing migration and dispersion of the plume .
The study also concluded that Lagoon 1 was a possible contributor of gross beta activity to groundwater downgradient of the Lagoon .
Figure 4-14 shows the 1E+03 pCi/L gross beta contour lines defining the extent of the plume in 1994, 2002, and 2008 . (This figure , which duplicates Figure 2-6 in Section 2, is provided here for the sake of completeness.) Figure 4-14 also shows gross beta concentrations at the 11 routine groundwater monitoring locations that define the plume as of December 2008 . Contour lines show a gradual lengthening and expansion of the plume toward the northeast, with the highest concentration (i.e ., well 408 at 3.17 E+05 pCi/L) near the Process Building and lower concentrations near the leading edge. Characterization sampling in 2008 has better defined the leading edge of the plume (WVES 2009b) . The most recent delineation, as defined by the 1000 pCi/L gross beta isopleth, indicated that the leading edge was split into three lqbes, and that the northern lobe is beginning to encroach on the Construction and Demolition Debris Landfill. Figure 4-14 also shows 1 E+03 pCi/L contour lines of gross beta activity in groundwater over time near inactive Lagoon 1. This smaller area of elevated activity, likely associated with contamination remaining in Lagoon 1 sediment and backfill, appears to be migrating slightly eastward over time.
Revision 2 4-65
WVDP PHASE 1 D ECO MMISSIONING PLAN
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WVDP PHAS E 1 DECOMMISSIONING PLAN
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Isopleth lines at 1E+03 pCi/L ~~--.=------:,..--..,------~ / .
(Strontium-90 DCG)
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Figure 4-14. North Plateau Groundwater Plume Revision 2 4-67
WVDP PHAS E 1 DECOMMISSIONING PLAN 4.3 References Code of Federal Regulations 10 CFR 50, Domestic Licensing of Production and Utilization Facilities.
10 CFR 835, Occupational Radiation Protection .
Other References Carpenter and Hemann 1995, Subsurface Probing Investigation on the North Plateau at the West Valley Demonstration Project, WVDP-220, Rev. 0. Carpenter, B. and M.
Hemann, West Valley Nuclear Services Company, West Valley, New York, April 26, 1995.
Choroser 2003 , Product Purification Cell (PPG) Radioisotope Inventory Report, RIR-403-022 , Revision 0. Chorosor, J., West Valley Nuclear Services Company, West Valley, New York, November 24, 2003 .
Choroser 2004, Liquid Waste Cell Radioisotope Inventory Report, RIR-403 -023, Revision
- 0. Choroser, J., West Valley Nuclear Services Company, West Valley, New York, July 21, 2004 .
Choroser, 2005 a, General Purpose Cell (GPC) Radioisotope Inventory Report, RIR-403 -
036, Revision 1. Choroser, J., West Valley Nuclear Services Company, West Valley, New York, January 25 , 2005 .
Choroser, 2005b, Process Mechanical Cell (f!MC) Radioisotope Inventory Report, RIR-403-037 , Revision 1. Choroser, J., West Valley Nuclear Services Company, West Valley, New York, January 25, 2005 .
Drobot 2003, Sample Storage Cell (SSC), Radioisotope Inventory Report, RIR-403-014, Revision 0. Drobot, A., West Valley Nuclear Services Company, West Valley, New York, April 30, 2003.
EG&G/EM 1984, An Aerial Radiological Survey of the WEST VALLEY DEMONSTRATION PROJECT and Surrounding Area, EG&G/EM Survey Report, EGG-10617-1080.
EG&G/EM, La s Vegas, Nevada, 1984.
Fazio 2001 , Data Collection and Analysis Plan (OAP) for Tanks 80-1 and 80-2 As Part of the Waste Tank Farm (WTF) Project, WVDP-364, Revision 3. Fazio, J.M., West Valley Nuclear Services Company, West Valley, New York, November 14, 2001 .
Fazio 2002a, Waste Storage Tank 80-3 Radioisotope Inventory Report, WVDP-364-003 ,
Revision 0. Fazio, J.M., West Valley Nuclear Services Company, West Vall ey, New York, September 24, 2002 .
Fazio 2002b, High-Level Waste Tank 80-1 and 80-2 Radionuclide Inventory Report as of
- September 1, 2002, WVDP-364-001, Revision 0. Fazio, J.M., West Valley Nuclear Services Company, West Valley, New York, September 30, 2002 .
Revision 2 4-68
WVDP PHASE 1 DECOMMISSIONING PLAN Fazio 2002c, Supernatant Treatment System (STS) Valve Aisle Radionuclide Inventory Report, RIR-403-007, Revision 0. Fazio, J.M., West Valley Nuclear Services Company, West Valley, New York, November 7, 2002 .
Fazio 2004a, Fuel Receiving and Storage (FRS) Radioisotope Inventory Report, RIR-403 -
013 , Revision 1. Fazio, J., West Valley Nuclear Services Company, West Valley, New York, February 5, 2004.
Fazio 2004b, Balance of the Waste Tank Farm Radioisotope Inventory Report, RIR-403-029, Revision 0. Fazio, J. , West Valley Nuclear Services Company, West Valley, New York, February 25 , 2004 .
Fazio 2004c, Waste Storage Tank 8D-4 Radioisotope Inventory Report, WVDP-364-006 ,
Revision 2. Fazio, J.M. , West Valley Nuclear Services Company, West Valley, New York, March 12, 2004 .
Hann um 1983, Letter from W.H. Hannum, DOE, West Valley Project Office, to T.K.
DeBoer, NYSERDA, Subj ect: "Ground Measurement Support of a Section of an Aeri al Radiologi cal Measuring Survey," January 25 , 1983 .
Hemann and Fallon 1998, 1997 Geoprobe Investigation of the North Plateau at the West Valley Demonstration Project, WVDP-298 , Revision 0 . Hemann N. and B. Fallon, West Valley Nuclear Services Company, West Valley, New York, January 15, 1998 .
Hemann and Steiner 1999. 1998 Geoprobe Investigation in the Core Area of the North Plateau Groundwater Plume , WVDP-346 , Rev . 0, Hemann, M. and R. Steiner, West Valley Nuclear Services Company, West Valley, New York, June 11 , 1999.
ISCORS 2005, ICORS Assessment of Radioactivity in Sewage Sludge: Recommendations on Management of Radioactive Materials in Sewage Sludge and Ash in Public Owned Treatment Works , ISCORS Technical Report 2004-04 . lnteragency Steering Committee on Radiation Standards, Washington , D.C., February 2005 .
Jenquin, et al. 1992, (;haracterization of Reactor Fuel Reprocessed at West Valley, WVDP-EIS-014, Revision 0. Jenquin, et al., Pacific Northwest Laboratory, Richland ,
Washington , February 1992.
Klenk 2009, West Valley Demonstration Project North Plateau Background Soil Characterization Report, WVDP-493 , Revision 2. Klenk, D.P., West Valley Environmental Services LLC, West Valley, New York, February 24, 2009 .
Lachapelle 2003, Vitrification Facility (VF) Radioisotope Inventory Report RIR-403 -010, Revision 1. Lachapelle, E., West Valley Nuclear Services Company, West Valley, New York, June 17, 2003 .
Luckett 1995, New York State Energy Research and Development Authority Western New York Nuclear Service Center Off-Site Radiation Investigation . Luckett, L., Dames and Moore, Pearl River, New York, April 20, 1995 .
Revision 2 4-69
WVDP PHASE 1 DECOMMISSIONING PLAN Luckett, et al. 2004, Radioisotope Inventory Report for Underground Lines and Low Level Waste Tanks at the West Valley Demonstration Project. WSMS-WVNS-04 -0001 .
Luckett, L.. J. Fazio, and S. Marschke, Washington Safety Management Solutions, Aiken, South Carolina , July 6, 2004.
Mahoney 2002, Bounding Isotope Ratios for NFS Spent Fuels, Memorandum Fl:2002 :0003 . Mahoney, J .L .. West Valley Nuclear Services Company, West Valley, New York, January 19, 2002 .
March etti 1982, WVDP : 014, Environmental Characterization of the Nuclear Fuel Reprocessing Plant at West Valley, New York (Presolidification Baseline) , West Valley Nuclear Services Company, Inc .. West Valley, New York, October 1982.
McNeil 2005a , Radioactivity in the Process Building at the Western New York Nuclear Service Center: Residual Radioactivity Estimate in Support of Decommissioning EIS Alternative 3, WSMS-LIC-04 -0151 , Revi sion 0. McNeil , J .. Wa shington Safety Management Solutions, Aiken , South Carolina , February 2, 2005 .
McNeil 2005b, Radioactivity in Subsurface Structures and Equipment in the Process Building Area at the Western New York Nuclear Service Center: A Residual Radioactivity Estimate in Support of Decommissioning EIS Alternative 4, WSMS-OPS-05-0001 , Revision 1. McNeil, J .. Washington Safety Management Solutions, Aiken, South Carolina , July 15, 2005 .
Michalczak 2002a, Miniature Cell (MC) Radioisotope Inventory Report, RIR-403-001 ,
Revision 0. Michalczak, L., West Valley Nuclear Services Company, West Valley, New York, September 13, 2002 .
Michalczak 2002b, Off-Gas Blower Room (OGBR) Radioisotope Inventory Report, RIR-403-002, Revision 0. Michalczak, L .. West Valley Nuclear Services Company, West Valley, New York, September 27, 2002 .
Michalczak 2003a, Chemical Process Cell (CPC) Radioisotope Inventory Report, RIR-403-009, Revision 0. Michalczak, L .. West Valley Nuclear Services Company. West Valley, New York, April 29, 2003 .
Michalczak, 2003b, Equipment Decontamination Room (EDR) Radioisotope Inventory Report, RIR-403-008, Revision 0. Michalczak, L.M .. West Valley Nuclear Services Company, West Valley, New York, April 29, 2003 .
Michalczak 2003c, Head End Ventilation Cell (HEV) Radioisotope Inventory, RIR-403-012, Revision 0. Michalczak, L .. West Valley Nuclear Services Company, West Valley, New York, April 29, 2003 .
Michalczak 2004a, Characterization Management Plan for the Facility Characterization Project, WVDP-403, Revision 3. Michalczak, L., West Valley Nuclear Services Company, West Valley, New York, January 16, 2004.
Michalczak 2004b, Low Ranking Areas of the Process Building Radioisotope Inventory Report, RIR-403-033 , Revision 0. Michalczak, L., West Valley Nuclear Services Company, West Valley, New York, June 2, 2004 .
Revision 2 4-70
WVDP PHASE 1 DECOMMISSIONING PLAN Michalczak 2004c, Balance of the Process Building Radioisotope Inventory Report, RIR-403-034, Revision 0. Michalczak, L.. West Valley Nuclear Services Company, West Valley, New York, Novemb'er 11 , 2004 .
Michalczak 2007 , Sample and Analysis Plan for Characterization of the North Plateau Plume Area, WVDP-465 , Revision 0. Michalczak, L .. West Valley Nuclear Services Company, West Valley, New York, August 16, 2007 .
Michalczak 2009, West Valley Demonstration Project, North Plateau Characterizafjon Report, WVDP-494, Revision 0. Michalczak, L., West Valley Environmental Services LLC, West Valley, New Yorik, Apnil 28, 2009.
NRC 1994, NUREG-1501 . Background as a Residual Radioactivity Criterion for Decommissioning. Draft Report for Comment. U.S . Nuclear Regulatory Commission, Washington, D.C .. August 1994.
NRC 1998 . NUREG-1505, Rev. 1. A Nonparametric Statistical Methodology for the Design and Analysis of Final Status Decommissioning Surveys. U.S . Nuclear Regulatory Commission, Washington, D.C .. September 1998.
NRC 2000, Multi-Agency Radiation Survey and Site Investigation Manual. NUREG-1575 ,
Revision 1. U. S. Nuclear Regulatory Commission, Washington, D.C .. August 2000.
NRC 2003, U.S. Nuclear Regulatory Commission (NRG) Staff Comments on U.S.
Department of Energy (DOE) West Valley Characterization Reports for the Waste Tank Farm. U.S . Nuclear Regulatory Commission, Washington , D.C .. December 4, 2003 .
NRC 2006, NUREG-1757 , Consolidated NMSS Decommissioning Guidance, Volume 1, Revision 2. U.S . Nuclear Regulatory Commission, Washington, D.C .. September 2006.
Passuite and Monsalve-Jones 1993, Environmental Information Document, Volume IV: Site Radiological Surveys, WVDP-EIS-007 , Revision 0. Passuite, M.F . and R.
Monsalve-Jones, West Valley Nuclear Services Company, West Valley, New York, February 11 , 1993 .
Sheskin, D.J . 1997 . Handbook of Parametric and Nonparametric Statistical Procedures.
Sullivan 1995, Low-Level Waste Treatment Facility Waste Characterization Report, WVDP-EIS-019, Revision 1. Sullivan, T .. West Valley Nuclear Services Company, West Valley, New York, May 17, 1995 .
URS 2000, Estimated Radionuclide Inventory for the NRG-Licensed Disposal Area at the West Valley Demonstration Project, Volume 1. URS Corporation, Orchard Park, New York, August 2000.
Revision 2 4-71
WVDP PHASE 1 DECOMMISSIONING PLAN URS 2001, Radiological Data Gap Analysis. URS Corporation, Orchard Park, New York, February 18, 2001 .
URS 2002a, SDA Radiological Characterization Report, URS Corporation, Orchard Park, New York, September 20, 2002 .
URS 2002b, Supplemental Hydrologic Investigation of the North Plateau Pilot Permeable Treatment Wall: Performance Assessment and Evaluation of Potential Enhancements, informal report to DOE . URS Corporation, Orchard Park, New York, November 2002 .
Westcott 1998, Memorandum from D.R. Westcott on Expanded Source Term for the North Plateau Groundwater Plume, 2301/AOC-09. West Valley Nuclear Services Company, West Valley, New York, January 15, 1998.
WVES 2008a, Transmittal of Estimated Demolition Ready Radiological Inventory of the Main Plant Process Building (MPPB) at the West Valley Demonstration Project, WZ:2008 :0002 , AC-WOP . Letter from West Valley Environmental Services (D .
Kurasch) to Washington Safety Management Solutions (D . Westcott) dated January 3, 2008 .
WVES 2008b, Estimated Demolition Ready Radiological Inventory of the Vitrification Facility (VF) at the West Valley Demonstration Project, WZ :2008 :0007 , AC-WOP.
Letter from West Valley Environmental Services (D. Kurasch) to Washington Safety Management Solutions (D . Westcott) dated January 7, 2008 .
WVES 2008c, Transmittal of Estimated Radiological and RCRA Hazardous Inventory in Tanks BD-3 and BD-4, AC-WOP , WZ:2008:0006. Letter from West Valley Environmental Services (D . Kurasch) to Washington Safety Management Solutions (D. Westcott) dated January 8, 2008 .
WVES 2008d, WVDP-098 . Environmental Monitoring Program Plan . Rev. 15. West Valley Environmental Services LLC . West Valley, New York, January 7, 2008.
WVES 2008e, WVDP-239. Groundwater Monitoring Plan . Rev. 12 . West Valley Environmental Services LLC, West Valley, New York, February 12, 2008 .
WVES 2008f, Safety Analysis Report for Waste Processing and Support Activities, WVNS-SAR-001, Revision 12. West Valley Environmental Services LLC , West Valley, New York, December 3, 2008 .
WVES 2009a, Sampling and Analysis Plan for the Waste Tank Farm Characterization Project, WVDP-451 , Revision 2. West Valley Environmental Services LLC, West Valley, New York, June 18, 2009 .
WVES 2009b, WVDP North Plateau Characterization to Support Design of Strontium-90 Groundwater Plume Mitigation Measure(s), WVDP-500, Revision 0. West Valley Environmental Services LLC, West Valley, New York, September 28, 2009.
Revision 2 4-72
WVDP PHASE 1 DECOMMISSIONING PLAN WVES 2009c, S111mmary Design Criteria, Waste Tank Farm Tank and Vault Drying System, WVNS-SDC -128, Revision 3. West Valley Environmental Services LLC , West Valley, New York, December 8, 2009.
WVES and URS 2009, West Valley Demonstration Project Annual Site Environmental Report Calendar Year 2008. West Valley Environmental Services LLC and URS Washington Division, West Valley, New York, September 2009 .
WVNS 1991 . West Valley Demonstration Project Site Environmental Report for Calendar Year 1990. West Valley Nuclear Services, Inc. West Valley, New York. May 1991 .
WVNSCO 1989, Safety Analysis Report, WVNS-SAR-002, Revision 2, West Valley Nuclear Services Company, West Valley, New York, June 1989.
WVNSCO 1994, Environmental Information Document, Volume IV: Soils Characterization, WVDP-EIS-008, Revision 0. West Valley Nuclear Services Company, West Valley, New York, September 15, 1994.
WVNSCO 1995, Resource Conservation and Recovery Act Facility Investigation Report, Volume 2, Nuclear Regulatory Commission-licensed Disposal Area, WVDP-RFl-018 . West Valley Nuclear Services Company, West Valley, New York, September 1995 .
WVNSCO 1996a, Resource Conservation and Recovery Act Facility Investigation Report, Volume 3, Construction and Demolition Debris Landfill, WVDP-RFl-019. West Valley Nuclear Services Company, West Valley, New York, April 1996.
WVNSCO 1996b, Resource Conservation and Recovery Act Facility Investigation Report, Volume 7, Chemical Process Cell Waste Storage Area, WVDP-RFl-023 . West Valley Nuclear Services Company, WVDP-RFl-023 , December 1996.
WVNSCO 1997a, Resource Conservation and Recovery Act Facility Investigation Report, Volume 4, Low-level Waste Treatment Facility, WVDP-RFl-021 . West Valley Nuclear Services Company, West Valley, New York, January 1997.
WVNSCO 1997b, Resource Conservation and Recovery Act Facility Investigation Report, Volume 5, Miscellaneous Small Units, WVDP-RFl-020. West Valley Nuclear Services Company, West Valley, New York, January 1997.
WVNSCO 1997c, Sampling and Analysis Plan (SAP) for Contaminated Soil Generated at or Near the Nuclear Regulatory Commission-Licensed Disposal Area (NOA) ,
WVDP-282, Revision 0. West Valley Nuclear Services Company, West Valley, New York, August 14, 1997.
WVNSCO 1998, Work Order for Relocating 55-G -003 Mob Pump, Number 9702831 , Field Change 6. West Valley Nuclear Services Company, West Valley, New York, March 1, 1998.
WVNSCO 2001 , Waste Incidental to Reprocessing (WIR) Evaluation for HLW Mobilization and HLW Transfer Pumps from Tanks 8D-1 and 8D-2, WD :2001 :0720, Revision 4.
Revision 2 4-73
WVDP PHASE 1 DECOMMISSIONING PLAN West Valley Nuclear Services Company, West Valley, New York, November},
2001 .
WVNSCO 2003 . Radiation and Contamination Survey Report 121097. West Valley Nuclear Services Company. West Valley, New York, August 4, 2003 .
WVNSCO 2004a, WVDP Radiological Controls Manual, WVDP-010, Rev. 20. West Valley Nuclear Services Company, West Valley, New York, March 2004 .
WVNSCO 2004b . EM-74 . Radioanalytical Data Validation . Rev. 8. West Valley Nuclear Services Company, West Valley, New York, November 22, 2004 .
WVNSCO 2004c. EM-11. Documentation and Reporting of Environmental Data. Rev. 8.
West Valley Nuclear Services Company, West Valley, New York, December 27, 2004 .
WVNSCO 2004c, Vitrification Cell Final Radiation Survey, Rad iation and Contamination Survey Report 127623. West Valley Nuclear Services Company, West Valley, New York, December 27 , 2004 .
WVNSCO 2006, WVDP Radiological Controls Manual, WVDP-010, Rev. 27 . West Valley Nuclear Services Company, West Valley, New York, November 2006 .
WVNSCO and D&M 1996a, Resource Conservation and Recovery Act Facility Investigation Report, Volume 6, Low-level Waste Storage Area, WVDP-RFl -022. West Valley Nuclear Services Company and Dames and Moore, West Valley, New York, October 1996.
WVNSCO and D&M 1996b, Resource Conservation and Recovery Act Facility Investigation Report, Volume 7, Chemical Process Cell Waste Storage Area, WVDP-RFl-023 .
West Valley Nuclear Services Company and Dames and Moore, WVDP-RFl-023, December 1996.
WVNSCO and D&M 1997a, Resource Conservation and Recovery Act Facility Investigation Report, Volume 8, High-Level Waste Storage and Processing Area. WVDP-RFl-024. West Valley Nuclear Services Company and Dames and Moore, West Valley, New York, April, 1997.
WVNSCO and D&M 1997b, Resource Conservation and Recovery Act Facility Investigation Report, Volume 9, Maintenance Shop Leach Field, WVDP-RFl-025 . West Valley Nuclear Services Company and Dames and Moore, West Valley, New York, July 1997.
WVNSCO and D&M 1997c, Resource Conservation and Recovery Act Facility Investigation Report, Volume 10, Liquid Waste Treatment System, WVDP-RFl -026. West Valley Nuclear Services Company and Dames and Moore, West Valley , New York, May 1997 .
WVNSCO and Gemini 2005 , West Valley Demonstration Project Residual Radioactivity Inventory for the Waste Tank Farm Activity: Supplemental Report. West Valley Revision 2 4-74
WVDP PHASE 1 D ECOMMISSIONING PLAN Nuclear Services Company, West Valley, New York, and Gemini Consulting Company, Oak Ridge, Tennessee, February 7, 2005 .
WVNSCO and URS 2007 , West Valley Demonstration Project Annual Site Environmental Report, Calendar Year 2006. West Valley Nuclear Services Company and URS Group, Inc ., West Valley, New York, August 2007 .
Revision 2 4-75
WVDP PHASE 1 DECOMMISSIONING PLAN 5.0 DOSE MODELING PURPOSE OF THIS SECTION The purpose of this section is to describe dose modeling performed for Phase 1 of the decommissioning to establish cleanup criteria that will not limit options for Phase 2 of the decommissioning .
INFORMATION IN THIS SECTION Th is section provides the following information:
- Section 5.1 contains introductory material to place information in the following sections into context.
- Section 5.2 describes the base-case and alternative conceptual models and the mathematical model (RESRAD) used to develop derived concentration guideline levels (DCGLs) for 18 radionucl ides of interest in surface soil ,
subsurface soil , and streambed sediment. It identifies the results in terms of DCGLw values. It discusses the deterministic sensitivity analyses of model input parameters. It also describes the probabilistic uncertainty analysis and the multi-source model for subsurface soil DCGLs that was found to be limiting for many radionuclides of interest.
- Section 5.3 discusses considerations related to dose integration and describes analyses performed to ensure that cleanup criteria used in Phase 1 will not limit Phase 2 decommissioning options.
- Section 5.4 provides cleanup goals; describes the process for refining the DCGLs and these cleanup goals; addresses use of a surrogate radionuclide in field measurements; provides preliminary, order-of-magnitude dose assessments related to remediation of subsurface soil ; and provides for final dose assessments after completion of the Phase 1 final status surveys.
RELATIONSHIP TO OTHER PLAN SECTIONS To put into perspective the information in this section , one must consider:
- The information in Section 1 on the project background and those facilities and areas within the scope of this plan,
- The facility descriptions in Section 3,
- The information on site radioactivity in Section 4,
- The information in Section 6 on the as low as reasonably achievable (ALARA) analysis,
- The information in Section 9 on radiation surveys ,
- The information in Appendix C that supplements the content of this section ,
- The information in Appendix D on engineered barriers and groundwater flow fields , and
- The information in Appendix E on details of the probabilistic uncertainty analysis .
Revision 2 5-1
WVDP PHASE 1 DECOMMISSIONING PLAN 5.1 Introduction To help place the dose modeling into context, it is useful to consider information about the applicable requirements and guidance, information on the environmental media of interest, and information relevant to consideration of doses from different parts of the project premises , along with information on matters that could impact dose modeling such as long-term erosion and potential changes in groundwater flow.
5.1.1 Applicable Requirements and Guidance As explained in Section 1, certain areas of the project premises are being remediated in Phase 1 of the decommissioning to NRC's unrestricted release criteria in 10 CFR 20.1402. These criteria state that a site will be considered acceptable for unrestricted use if the residual radioactivity that is distinguishable from background radiation results in a total effective dose equivalent to an average member of the critical group that does not exceed 25 mrem per year, including that from groundwater sources of drinking water, and the residual radioactivity has been reduced to levels that are ALARA.
NRC provides guidance (NRC 2006) on two approaches that may be used to determine that these unrestricted release criteria have been achieved :
(1) The dose modeling approach , which involves chqracterizing the site - after remediation , if necessary - and performing a dose assessment; and (2) The DCGL and final status survey approach , which involves developing or using DCGLs and performing a final status survey to demonstrate that the DCGLs have been met.
NRC observes that the second option is *usually the more efficient or simpler method and that these two approaches are not mutually exclusive; they are just different approaches to show that the potential dose from a remediated site is acceptable (NRC 2006).
As explained below, DOE is using the DCGL approach in Phase 1 of the decommissioning and then , after remediation of subsurface soil in the two major areas of interest, will perform dose modeling using Phase 1 final status survey data to estimate potential future doses from these areas assuming the rest of the project premises were to also be cleaned up to the unrestricted release criteria in 10 CFR 20.1402 .
DCGLs and Cleanup Goals DCGLs are radionuclide-specific concentration limits used during decommissioning to achieve the regulatory dose standard that permit the release of the property and termination of the license . The DCGL applicable to the average concentration over a survey unit is called the DCGLw and the DCGL applicable to limited areas of elevated concentrations within a survey unit is called the DCGLEMC (NRC 2006). However, Phase 1 of the decommissioning will not result in the release of any property or in termination of the NRC license for the site. As explained below, cleanup goals below the DCGLs are used to ensure that Phase 1 criteria do not limit Phase 2 options.
5.1.2 Context for DCGL Development Figure 5-1 shows the areas of interest for surface soil , subsurface soil , and streambed sediment for which separate DCGLs have been developed. Each area is discussed below.
Revision 2 5-2
WVDP PHASE 1 DECOMMISSIONING PLAN 1 IA<
'I I ", N A
Low-Level Waste Treatment Facility Excavation, WMA 2 r
I Parts of Erdman Brook and Franks Creek are known to
(
- Surface soil in selected areas may be -~
remediated to surface soil cleanup goals I in Phase 1.
- The bottom and lower sides of the WMA 1 and WMA 2 excavation will be remediated to subsurface soil cleanup goals in Phase 1.
- Sediment in Erdman Brook and Franks Creek within the project premises will not be remediated in Phase 1.
Legend CJ ........_ _
LJ IWDP- \
~ Cmct9'e
"""*- 'INOP-F~
F<undlt\on
__.,_ WVOP RPspi;I'
.o-*-
Gl 3 -*-..
- - Qrffl'M 0
(
1.000 Feat Figure 5-1. Areas of Interest - Surface Soil, Subsurface Soil, and Streambed Sediment Within the Project Premises Revision 2 5-3
WVDP PHASE 1 DECOMMISSIONING PLAN Surface Soil As explained in Section 1 of this plan, surface soil and sediment in drainage ditches on the project premises will be characterized for radioactivity to better define the nature and extent of radioactive contamination . Section 4.2 summarizes available data on radioactivity in these environmental media. Available data indicate that radioactive contamination is present in some areas but the magnitude and areal extent of this contamination have not been fully defined . Figure 4-6 shows locations where soil and sediment are known to have radioactivity concentrations in excess of background .
Cs-137 concentrations in excess of background have been measured in surface soil samples from all waste management areas (WMAs) where samples have been collected ,
with the highest measured concentration being 280 pCi/g . Sr-90 concentrations above background have been measured in surface soil samples from several WMAs, with a maximum of 12 pCi/g . Data on other radionuclides in surface soil are very limited , but above-background concentrations of Pu-238, Pu-239/240 , and Am-241 have been identified as indicated in Section 4.2.
DCGLs for surface soil based on the unrestricted release criteria in 10 CFR 20 .1402 serve two purposes:
- They will support remediation of surface soil on selected portions of the project premises in Phase 1 of the decommissioning, and
- They will support decision-making for Phase 2 of the decommissioning .
The surface soil DCGLs and cleanup goals apply only to areas where there is subsurface contamination, i.e., contamination below a depth of one meter.
Subsurface Soil The subsurface soil DCGLs, which are also based on the unrestricted release criteria of 10 CFR 20.1402, apply only to the bottoms and lower sides of the two large excavations 1
to be dug to remove facilities in WMA 1 and WMA 2. Figure 5-2 shows a conceptual cross section view of the planned WMA 1 excavation with representative data on Sr-90 concentrations. Figure 5-3 shows a conceptual cross section view of the planned WMA 2 excavation with representative data . Both excavations will extend one foot or more into the Lavery till, as indicated in Section 7.
As explained in Section 1 and detailed in Section 7, the Process Building and the other facilities in WMA 1 will be completely removed during Phase 1 of the decommissioning ,
along with the source area of the north plateau groundwater plume. The excavation for this purpose will be approximately 2.8 acres in size and extend more than 40 feet below the ground into the unweathered Lavery till. Figure 5-1 shows the approximate location of this excavation.
1 The subsurface soil DCGLs will be applied to the sides of these excavations at depths greater than three feet below the surface ; the surface soil DCGLs would be applied to the portions of the excavation sides closer to the ground surface. Note that the sides of the excavations that are upgradient or cross-gradient (i.e., not
!hydraulically downgradient) of the contamination source are not expected to be contaminated .
These DCGLs may also be applicable to excavations made in Phase 2 of the decommissioning depending on the approach selected for Phase 2 and other factors if the conceptual models described in this section are representative of the Phase 2 conditions .
Revision 2 5-4
WVDP PHASE 1 DECOMMISSIONING PLAN I
{UPCRAOIENT EXTENT CEMENT~ ENTONIT£ or e:xc*vATION.) BARRIER (OOWNGRAOIE:NT E)(T£N OF" £>:06.VAllON) 1410 The subsurface soil cleanup goals will apply to the bottom of the excavation and to the sides Typical depth of water table I
. SAND AND GRAVEL UNIT ueo GP-23, GP-30, GP-72, and GP-75 indicate locations of subsurface samples collected with a Geoprobe'.
Data shown are from the 1998 Geoprobe investigation (Hemann and Steiner 1999).
Figure 5-2. Conceptual Cross Section View of WMA 1 Excavation With Representative Soil Data on Sr-90 Concentrations (See Section 4.2 for more data and Section 7 for the excavation details.)
Revision 2 5-5
WVDP PHASE 1 DECOMMISSIONING PLAN J IGISIArcMa /EIS/La oon Cross Section A r1 .mxd 2/04/2000 JR c Sand & Gravel See Table 2-18 for estimated Sand & Gravel A A' residual radioactivity in Lagoon 1.
Sand & Gravel/ The subsurface soil cleanup goals will apply to Elevation Bevation (Feet ab011e Lavery Till Interface the bottom of the excavation and to the sides (Feet above mean sea level) mean sea leveQ more than three feet below the surface.
1410 1'10 1405 1'05 1400 1'00 1395 See Table 4-14 for maximum 1395 radioactivity concentrations measured 1390 in La~oon 2 and La~ oo n 3 sediment.
1385 1385 1380 Proposed Extent 1380
____!lli:!L_
o.z [)epth of Exca vation 1375 Cs137 - 280 pC~g Sr90. 4 1 pC.Jg 1370 1365 I 1365 I
1360 ---------------,............ Sand & Gravel/
1 I 1300 18'*20' Oeptn ...... ......... Lavery Till Interface /
1366 Am2~ 1
- 0 09 pC~g CSl 37
- 2.7 ~g . . ........... /
-~-~-----~--------'
P\1238. 0 02 ~g 1350 '- ~ 1350 Sr90 . 0 18 pCi/g Vertica l Exaggeration = -5 .3x Soil radioactivity data are from the 1993 soil sampling program (VWNSCO 1994)
Figure 5-3. Conceptual Cross Section View of WMA 2 Excavation With Representative Data on Subsurface Soil Contamination (See Section 4.2 for more data and 7 for excavation details.
Revision 2 5-6
WVDP PHASE 1 DECOMMISSIONING PLAN Available data on radioactive contamination in subsurface soil in WMA 1 described in Section 4.2 show Sr-90 to be the dominant radionuclide at depth. Figure 4-8 shows key data, which include three samples from several feet into the unweathered Lavery till that show Sr-90 concentrations of 13 pCi/g, 41 pCi/g, and 59 pCi/g at depths in the 35 to 40 feet range.
Other radionuclides with measured above-background concentrations in subsurface soil in WMA 1, with their maximum concentrations and the associated sample depth ,
include: Tc-99 {19 pCi/g at 19-23 feet), Cs-137 {31 pCi/g, at 27 to 29 feet) , Pu-241 (15 pCi/g at 21 to 23 feet), and Am-241 (0 .1 pCi/g, 19 to 23 feet) . Table 5-1 shows the maximum measured radionuclide concentrations in the Lavery till in the areas of the large excavations in WMA 1 and WMA 2. Data in the Lavery till in these areas are limited - the complete set of data is provided in Table C-4 of Appendix C.
Table 5-1. Measured Maximum Lavery Till Radionuclide Concentrations<1 l WMA 1 Excavation Area WMA 2 Excavation Area Nuclide Result (pCi/g) Depth (ft) Result (pCi/g)<3l Depth (ft)
C-14 1.1E-01 (2 l 38-40 none none 4
Sr-90 5.9E+01 ( l 38.5-39 8.5E-01 12-14 2
Tc-99 <5.5E-01 <l 37-39 none none 2
1-129 <2 .9E-01 ( l 38-40 none none 2
Cs-137 3 .9E+00( l 38-40 4.5E-01 12-14 U-232 4.1 E-02 24-26 1.2E-02 12-14 2
U-233/234 2.3E+oo< l 38-40 1.8E-01 12-14 U-235 1.4E-01 <3 l(5l 24-26 <5.9E-03 12-14 2
Np-237 <2.1 E-02( ) 37-39 none none U-238 1.4E+OO 41-43 1.1E-01 12-14 Pu-238 <2 .3E-02(2 l 38-40 1.0E-02 12-14 2
Pu-239/240 <6.4E-02( l 38-40 <5.9E-03 12-14 2
Pu-241 <5.7E-01 ( l 38-40 <1.3E+OO 12-14 2
Am-241 <1.3E-01 ( l 38-40 3.0E-02 12-14 2
Cm-243/244 <2.3E-02( l 38-40 none none NOTES: (1) See Table C-4 for the complete data set, which includes samples at nine locations entirely within the unweathered Lavery till within the WMA 1 excavation area . Based on boring log data, only one sample (BH: 05) taken within the WMA 2 excavation area contained only unweathered Lavery till soil ; the others contained some soil from the sand and gravel layer.
(2) Data are from the 2008 north plateau groundwater plume Geoprobe"' investigation described in Section 4, with the highest non-detection values recorded (with amended sample 7608 results).
( 3) Data are from sample BH-05 collected during the 1993 RCRA facility investigation described in Section 4 ..
(4) Data are from point GP3098 from the 1998 north plateau Geoprobe"' sampling described in Section 4.
(5) U-235/U-236 result.
Revision 2 5-7
- WVOP PHASE 1 DECOMMISSIONING PLAN Additional Characterization Planned The characterization program described in Section 9 will provide additional data on radioactivity in subsurface soil in WMA 1 and WMA 2 and lagoon sediment in WMA 2.
The actual depth of the WMA 1 excavation will e>Ctend at least one foot 1into the unweathered Lavery, and this is where the subsurface soil cleanup goals will apply, as explained in Section 7. The configuration of the residual source will therefore be similar to the bottom of the excavation shown in the representative cross section in Figure 5-2 .
Figure 5-1 also shows the approximate location of the major excavation in WMA 2. As explained in Section 1 and detailed in Section 7, a single excavation will be made to remove Lagoons, 1, 2, and 3, the interceptors, the Neutralization Pit, and the Solvent Dike.
The area of this excavation will be approximately 4.2 acres and its depth will vary from 2
approximately 12 feet on the southwest end to approximately 26 feet on the northeast end .
Figure 5-3 shows a conceptual cross section of the WMA 2 excavation . This figure also shows representative data on subsurface radioactivity. As indicated on the figure , Table 2-18 provides an estimate of residual radioactivity in Lagoon 1 and Table 4-14 shows maximum radionuclide concentrations measured in sediment in Lagoon 2 and Lagoon 3.
As indicated in order-of-magnitude estimates in Table 2-18, Cs-137 (at 510 curies) is expected to dominate the radioactivity in Lagoon 1. Other radionuclides expected to be present include Pu-241 (134 curies) , Sr-90 (17 curies), and Pu-238 (6.4 curies). Table 4-14 shows significant concentrations of Sr-90, Cs-137, Pu-238, Pu-239/240, and Am-241 in Lagoon 2 sediment and lower concentrations of these radionuclides in Lagoon 3 sediment.
The actual depth of the WMA 2 excavation will extend at least one foot into the unweathered Lavery, and this is Where the subsurface soil cleanup goals will apply , as explained in Section 7. In the cases of Lagoon 2 and Lagoon 3, the excavation will extend approximately two feet below the bottom the lagoons, which extend into the Lavery till. The configurat_ ion of the residual source will therefore be similar to the bottom of the excavation shown in the representative cross section in Figure 5-3 .
While the subsurface soil cleanup goals serve as the remediation criteria for the two excavations as specified in Section 7, actual residual contamination levels in the Lavery till are expected to be well below these criteria. The concentrations of Sr-90 and Cs-137 are expected to be of the same order of magnitude as the lower surface soil cleanup goals.
This conclusion is based on contamination data shown in Table 5-1 and the relative impermeability of the Lavery till to radionuclide migration compared to the sand and gravel layer above it.
2 The 26-foot estimate is based on using the ground surface adjacent to Lagoon 3 as a reference point. The excavation is expected to extend several feet below the bottoms of Lagoons 2 and 3 to remove sediment with radioactivity concentrations above the cleanup _goals.
Revision 2 5-8
WVDP PHASE 1 DECOMMISSIONING PLAN Streambed Sediment Streambed sediment refers only to sediment in Erdman Brook and the portion of Franks Creek running through the project premises. Figure 5-12 in Section 5.2 below shows precisely where streambed sedimernt DCGLs apply.
Surface soil DCGLs will be applied to sediment in ditches, in tributaries to Erdmarn Brook and Franks Creek. and in other parts of the project premises, with the subsurface soil DCGLs being applied to the bottom of Lagoons 2 and 3. Unique DCGLs are appropriate for Erdman Brook and Franks Creek because the areas of these streams would not support farming or grazing of livestock as would other areas of the project premises, owing to the steep stream banks.
Section 4.2 summarizes the limited available data on radioactivity in the sediment of Erdman Brook and the portion of Franks Creek on the project premises. Figure 4-6 shows sample locations , with five in Erdman Brook and four in Franks Creek. Table 4-22 shows the highest measured concentrations of Cs-137 and other radionuclides . The highest measured Cs-137 concentration was 100 pCi/g and the highest Sr-90 concentration was 10 pCi/g . (However, Section 4.2 describes a hot spot found in Erdman Brook in 1990 with a gamma radiation level of 3000 µR/h ; a sample collected at that location showed 10,000 pCi/g Cs-137.) The characterization program described in Section 9 will provide additional data on radioactivity in the sediment of the two streams .
DCGLs (cleanup goa~ s) for streambed sediment based on the unrestricted use criteria in 10 CFR 20.1402 will support decision-making for Phase 2 of the decommissioning, and remediation of contaminated sediment in Erdman Brook and the portion of Franks Creek on the project premises is this were to be accomplished in Phase 2.
5.1.3 Context for the Integrated Dose Assessment Three sets of DCGLs have been developed as described in Section 5.2 to be applied to the particular areas of interest, that is:
- Surface soil DCGLs for surface soil and for sediment in drainage ditches on the project premises and in tributaries to Erdman Brook and Franks Creek, and for the sides of the WMA 1 and WMA 2 excavations from the ground surface to three feet below the surface;
- Subsurface soil DCGLs for the bottoms of the WMA 1 and WMA 2 excavations and for the excavation sides more than three feet below the ground surface ; and
- Streambed sediment DCGLs for sediment in Erdman Brook and the portion of Franks Creek on the project premises shown in Figure 5-12 .
Each set of DCGLs was developed as if the area of interest remediated to the applicable DCGLs were to be the only area to which a hypothetical future resident or recreation ist might be exposed . However, it is more likely that a variety of receptors will be exposed to multiple sources under a range of land use scenarios. Considering each source Revision 2 5-9
WVDP PHASE 1 DECOMMISSIONING PLAN independently allows for flexibility in subsequent combined dose evaluations, as discussed further in Section 5.3.
Phase 1 and Phase 2 Sources Inherent in the phased decision-making approach is the concept of Phase 1 and Phase 2 sources. Figure 5-4 identifies these different sources.
Phase 1 sources are those to be remediated during Phase 1 of the decommissioning :
mainly the WMA 1 area and the large area in WMA 2 to be excavated . Surface soil in selected areas within the project premises may or may not be remediated in Phase 13 .
Based on current characterization data , the main Phase 2 sources are the non-source area of the north plateau groundwater plume in WMA 2, WMA 4, and WMA 5; the Waste Tank Farm in WMA 3, and the NRC-Licensed Disposal Area (NOA) in WMA 7.
The table at the bottom of the Figure 5-4 shows the approximate amounts of total radioactivity in the different source areas based on estimates provided in Section 4. In this illustration , the remediated WMA 1 and WMA 2 excavated areas are the Phase 1 sources.
The Waste Tank Farm , the non-source area of the north plateau groundwater plume, and the NOA are the Phase 2 sources, as is low-level contaminatiion in streambed sediment.
Low-level contamination in surface soil - which may or may not be remediated during Phase 1 - could be either be a Phase 1 (remediated) or Phase 2 (remediated or not) source, with the potential impact from this sources much smaller than for the others (with the exception of stream bed sediment).
Figure. 5-4 shows other features of the project premises at the conclusion of the Phase decommissioning activities that could potentially influence future doses from residual radioactivity on the project prem ises :
- Groundwater flow, with the water table in the sand and gravel unit on the north plateau, with elevations expressed in feet above mean sea level , and the current pre-remediation general direction of groundwater illustrated on the figure ;
- The full-scale Permeable Treatment Wall ; and
- The hydraulic barrier walls to be installed during Phase 1 of the decommissioning as described in Section 7 and the French drain to be emplaced upgradient of the WMA 1 hydraulic barrier wall.
The effectiveness of these features impacts potential future doses to the receptor and overall contribution to the evaluation of combined dose from all sources.
3 As noted in Section 7.11 , surface soil in selected areas of the project premises may be remediated during the Phase 1 decommissioning activities to ensure that surface soil cleanup goals are achieved in these areas.
Revision 2 5-10
WVDP PHASE 1 DECOMMISSIONING PLAN Full-Scale Permeable Treatment Wall*
French Drain Installed During Phase 1
- The configuration shown is not based on the final design. t 0 3 WMA 1 excavation Area 30-45 ft. below grade remediated below subsurface DCGLs for unrestricted release 2 WMA 2 excavation Area 12-26 ft. below grade remediated below subsurface DCGLs for unrestricted release Waste Tank Farm Underground tanks with -345,000 curies in*2011 4 North plateau plume Contaminated subsurface soil and groundwater, - 40 curies Sr-90 in 2041 5 Surface soil Low-level contamination in some areas, may be remediated below DCGLs 6 Stream beds Low-level contamination, especially Cs-137, may be remediated below DCGLs 7 NOA NRG-Licensed Disposal Area buried waste containing - 180,000 curies in 2011 Figure 5-4. Sources at the Conclusion of Phase 1 of.the Decommissioning Revision 2 5-1 1
WVDP PHASE 1 DECOMMISSIONING PLAN Potential Conditions at the Conclusion of the WVDP Decommissioning To determine whether criteria used in Phase 1 remediation activities could potentially limit the decommissioning options for Phase 2 of the decommissioning , consideration must be given to potential approaches to Phase 2. The De.commissioning EIS evaluates a range of closure alternatives. Two of these alternatives provide bounding conditions for assessment of whether the criteria used for Phase 1 remediation activities could limit Phase 2 options:
- The site-wide close-in place-alternative, where the major facilities would be closed in place, with residual radioactivity in the Waste Tank Farm and the NOA being isolated by engineered barriers and the non-source areas of the north plateau groundwater plume being allowed to decay in place; and
- The site-wide removal alternative, where the Phase 2 sources would be removed and the entire site remediated to the unrestricted release criteria of 10 CFR 20 .1402.
Compatibility of Phase 1 Remediation With the Site-Wide Close-In-Place Alternative With the site-wide close-in place-alternative , the Phase 2 source areas would likely remain under NRC license. With Phase 1 of the decommissioning being accomplished , the contamination remaining in the WMA 1 and WMA 2 excavations will be residual radioactivity at concentrations below the subsurface soil cleanup goals located far below the surface and covered with uncontaminated earth .
Under a site-wide close-in-place approach , the remediated Phase 1 areas would be expected to fall within the controlled licensed area because of their close proximity to the Phase 2 source areas. In view of this situation , the remediation of the Phase 1 areas to unrestricted release standards would clearly be compatible with the Phase 2 source areas remaining under license. That is, remediation of the Phase 1 source areas as planned will have no impact on the site-wide close-in place-alternative and will not limit its implementation in any way.
Compatibility of Phase 1 Remediation With the Site-Wide Removal Alternative Under the site-wide removal alternative, the Phase 2 source areas would be remediated to unrestricted release standards like the Phase 1 source areas. All of the associated radioactive waste will be disposed of offsite. However, while the remediation standards will be the same, the critical group for potential future exposures will not be the same for all parts of the site . Because remediation to unrestricted release standards under Phase 1 of the decommissioning does not preclude achievement of unrestricted release standards under Phase 2, all remedial options may be considered.
However, this situation requires consideration of potential exposures to members of the different critical groups, a matter which is addressed below.
Critical Group Critical Group means the group of individuals reasonably expected to receive the greatest exposure to residual radioactivity for any applicable set of circumstances ( 10 CFR 20.1003).
Revision 2 5-12
WVDP PHASE 1 DECOMMISSIONING PLAN Section 5.2 describes the critical groups for development of the different DCGLs . The average member of the critical group for development of the surface soil and subsurface soil DCGLs is a resident farmer. (Alternative scenario analyses described in Section 5. 2 also evaluate e.x;posure to a residential gardener.) The average member of the critical group for development of the streambed sediment DCGLs is a recreationist, that is, a person who would spend time in the Erdman Brook and Franks Creek areas engaged in activities such as fishing and hiking .
One reasonably foreseeable set of circumstances would involve a person engaged in fa rming at some time in the future on one part of the remediated project premises who also spends time fishing and hiking at Erdman Brook and Franks Creek. This scenario wou ld involve an individual being exposed to two different remediated source areas and being a member of the two different critical groups. Because this scenario is not considered in development of the DCGLs for the different areas of interest, it would be appropriate to consider whether it could result in such a hypothetical individual exceeding the unrestricted dose limit, that is, 25 mrem in one year, and whether the residual radioactivity has actually been reduced to levels that are ALARA in accordance with 10 CFR 20.1402 .
Considering the foregoing discussion , Section 5.3 evaluates the potential impacts of this set of circumstance (combined sources of dose to a single receptor) on the DCGLs and the associated cleanup goals to be used to guide remediation during Phase 1 of the decommissioning .
Two other factors that could potentially affect potential future doses from the remediated Phase 1 areas would be long-term erosion and potential changes in groundwater flow.
5.1.4 Potential Impact of Long-Term Erosion The potential impact of long-term erosion is a consideration in development of DCGLs for Phase 1 of the decommissioning and for estimating potential future doses from different parts of the project premises assuming that the entire site would be remediated for unrestricted use .
Section 3.5.3 of this plan describes the site geomorphology, including erosion processes such as channel incision , slope movement, and gully formation . Table 3-13 provides information on site erosion rates from various sources.
Detailed erosion studies performed in support of the Decommissioning EIS are described in Appendix F to that document. This appendix describes past studies and recent analyses that made use of the CHILD landscape evolution model, which was calibrated for the site using a probabilistic process .
The CHILD model was used for 26 forward-in-time simulations to predict erosion rates at the WVDP over a 10,000-year time period . The models generally predicted minimal erosion on the central portion of the north plateau , gully development along the north plateau rim , and active erosion along the steep valley sides of Erdman Brook and Franks Creek. In the more erosive north plateau scenarios, gullies were predicted to advance within 328 to 656 feet of the Process Building area within the 10,000 year simulation period .
Revision 2 5-13
WVDP PHASE 1 DECOMMISSIONING PLAN Limited field data showing actual sheet and rill erosion rates are available as indicated in Table 3-13. The maximum measured erosion among 19 measurements over an 11-year period ending in 2001 was 0.04 feet (approximately 0.5 inch) on the slope of a gully. One spot south of Lagoon 2 showed buildup of 0.04 feet (about 0.5 inch) during that period.
Conclusions that can be drawn from the available field data and the erosion studies detailed in Appendix F of the Decommissioning EIS include :
- The central portion of the north plateau is expected to be generally stable over the next 1000 years ;
- The WMA 2 area , which is near the Erdman Brook stream valley , is more susceptible to erosion than the WMA 1 area ;
- Existing gullies will propagate , becoming deeper and longer, and new gullies will form , mainly on the edges of the north plateau , if erosion proceeds unchecked ;
- Rim widening and channel downcutting could occur in Erdman Brook and Franks Creek;
- With unmitigated erosion , gullies could eventually extend into the areas of Lagoons 1, 2, and 3 during the 1000-year evaluation period ; and
- With unmitigated erosion , rim widening and downcutting of Erdman Brook could possibly impact the eastern edge of the areas of these lagoons, especially Lagoon 3.
These projections formed the basis for the alternate conceptual models involving erosion that are described in Section 5.2.
5.1.5 Potential Changes in Groundwater Flow Fields Changes in the groundwater flow pattern that might result from installation of the hydraulic barriers shown in Figure 5-1 could increase the potential for recontamination of the areas remediated in Phase 1. Groundwater in the sand and gravel unit on the north plateau currently flows northeast as indicated on Figure 5-4. With this flow pattern, and with the WMA 1 and WMA 2 hydraulic barriers remaining in place, the potential for transport of contaminants by groundwater into the WMA 1 and WMA 2 areas remediated during Phase 1 of the decommissioning from Phase 2 source areas is low.
Appendix D describes the results of an analysis performed to evaluate groundwater flow conditions near these engineered barriers. This analysis suggests that the potential for recontamination of the remediated WMA 1 and WMA 2 areas will not be significantly increased with the engineered barriers in place.
5.1.6 Seepage of Groundwater Figure 5-5 shows the locations of groundwater seeps on the north plateau. As can be seen in the figure , any groundwater from the seeps located on the project premises runs into Erdman Brook or Franks Creek (Dames and Moore 1994 ).
Revision 2 5-14
WVDP PHASE 1 DECOMMISSIONING PLAN
_.diSP-03 CWT(R or OBSERll(O y S((P.tCC POINT J.:>O'O-' *<TL~te Sc.o'e 'r:;(WNSW74A (l*tl)
)!X MO ITORINC LOCATION Figure 5-5. Locations of Perimeter Seeps on the North Plateau (From Dames and Moore 1994)
One other factor that could possibly affect conditions following Phase 1 of the decommissioning is seepage of radioactively contaminated groundwater into Erdman Brook and Franks Creek.
Revision 2 5-15
WVDP PHASE 1 DECOMMISSIONING PLAN As noted previously, streambed sediment wi ll not be remediated during Phase 1 of the decommissioning . The presence of groundwater seeps in the Erdman Brook area was one factor taken into account in the decision not to proceed with this remediation during Phase 1, since these seeps could possibly result in recontaminating the sediment in Erdman 4
Brook.
However, the potential for significant radioactivity in seeps in this area following Phase 1 of the decommissioning will be low due to the following factors :
- Any residual rad ioactivity that might remain in the Lavery till at the bottom of the remed iated WMA 2 excavation will be at very low concentrations ; and
- Groundwater flow changes with the Phase 1 vertical hydraulic barriers in place , as described in Append ix D, will be expected to substantially reduce the potential for contamination from the non-source area of the north plateau groundwater plume seeping into Erdman Brook.
Another fa ctor that was taken into account in the decision to not proceed with remediation of sediment in Erdman Brook and in the portion of Franks Creek on the project premises during Phase 1 of the decommissioning was surface water runoff, especially runoff from the two radioactive waste disposal areas on the south plateau . Surface water runoff from both waste disposal sites is potentially contaminated due to surface soil contamination in these areas, although the potential impact on the streams is limited so long as the geomembrane covers for the waste disposal sites remajn intact.
Note that Table 0-4 in Append ix D provides flow balance estimates for post-Phase 1 cond itions. These estimates do not show an increase in downward groundwater flow to the Kent Recessiona l Sequence following Phase 1 of the decommissioning .
5.1.7 Potential Impacts on the Kent Recessional Sequence The potential for impacts on groundwater in the Kent Recessional Sequence from any residual radioactivity that might remain in the bottom of the WMA 1 and WMA 2 excavated areas has been evaluated and found to be very low.
Groundwater in the sand and gravel unit generally flows to the northeast across the north plateau towards Franks Creek as shown in Figure 5-4. Water balance estimates (Yager 1987 and WVNSCO 1993a) suggest that approximately 60 percent of the groundwater from the sand and gravel unit discharges to Quarry Creek, Franks Creek, and Erdman Brook through surface water drainage discharge points and the groundwater seeps located along the margins of the north plateau that are shown in Figure 5-5.
Approximately two percent of the total discharge from the sand and gravel unit travels vertically downward to the underlying unweathered Lavery till , where groundwater flows verti cally downward toward the underlying Kent Recessional Sequence at an average vertical groundwater velocity of 0.20 feet per year (WVNSCO 1993a). The unweathered Lavery till is approximately 30 to 45 feet thick below the planned WMA 1 excavation and 40 to 110 feet thick below the planned WMA 2 excavation (WVNSCO 1993b).
4 Seeps could also release contamination into Quarry Creek. Quarry Creek lies outside of the project premises and is not within the scope of Phase 1 decommissioning activities.
Revision 2 5-16
WVDP PHASE 1 DECOMMISSIONING PLAN It will take approximately 200 years for groundwater to migrate through the unweathered Lavery till at WMA 1 and WMA 2 assuming a Lavery till thickness of 40 feet and an average groundwater velocity of 0.20 feet per year. Mobilization and migration of the residual radionuclide inventory at the bottom of the WMA 1 and WMA 2 excavations through the Lavery till groundwater pathway will take even longer considering the sorptive properties of the Lavery till (Table 3-20) .
Short-lived radionucl ides (Sr-90, Cs-137, and Pu-241) will have decayed away during these time frames . The long-lived radionuclide inventory is not an issue as the residual concentrations within the Lavery till are expected to be comparable to background concentrations for surface soil. The residual rad ionucl ide concentrations in the Lavery till in the bottom of the WMA 1 and WMA 2 excavations are expected to be lower than those reported in Table 5-1 and will therefore not significantly impact the Kent Recessional Sequence . Groundwater reaching the Kent Recessional Sequence flows laterally to the northeast at an average velocity of 0.40 feet per year and eventually discharges to Buttermilk Creek.
The potential for impacts on groundwater in Lavery till sand has also been considered .
The Lavery till sand is located 30 to 40 feet below grade within the Lavery till and is recharged by downward groundwater flow from the Lavery till . The Lavery till sand is located south of the WMA 1 excavation (Figure 3-64) and will not be impacted by the Phase 1 excavation of WMA 1.
However, the Lavery till sand underlies approximately 15,000 square feet of the southwestern most portion of WMA 2 near the Solvent Dike (Figure 3-64). The Solvent Dike was originally excavated in 1986 and will be excavated down into the Lavery till during the excavation of WMA 2. Because any residual radionuclide concentrations are expected to be less than those reported in Table 5-1 , groundwater flow from the Lavery till will not significantly impact the Lavery till sand .
Note that Section 9 provides for characterization surveys around selected Process Building foundation pilings to determ ine whether there might be evidence of contam inant migration along some of the pilings downward towards the Kent Recessiona l Sequence.
5.1.8 General Dose Modeling Process The general process for the dose modeling described in Section 5.2 and 5.3 is illustrated in Figure 5-6.
As indicated in the figure , the process involves the following major steps:
- Calculating the DCGLs using RESRAD in the deterministic mode to produce the initial base cases ;
- Performing parameter sensitivity analyses and refining the conceptual models and the DCGLs as appropriate based on the results ;
- Performing a probabilistic uncertainty analysis to evaluate the degree of conservatism in model input parameters, producing probabilistic peak-of-the-mean and 95th percentile DCGLs; Revision 2 5-17
WVDP PHASE 1 DECOMMISSIONING PLAN Develop deterministic DCGLs for 25 mrem/y using RESRAD (surface soil ,
subsurface soil , and streambed sediment)
~
Perform sensitivity analyses, recalculate DCGLs as indicated by results Perform probabilistic uncertainty
~ analysis to evaluate parameter -
conservatism r
Evalwate alternative conceptual
~
Determine most limiting DCGLs based on all modeling results
~ models, including multi-source -
model for subsurface soil DCGLs Analyze combined source Consider ALARA 4 area exposure . -, analysis results scenario (Section 6)
~
Establish cleanup goals below DCGLs based on results that will not limit Phase 2 options
\.
Characterize environmental media Use characterization data to
~ (Including surface soil, subsurface ~ refine DCGLs and cleanup .~
soil, and stream sediment) goals (except for surface soil) c:
.Q Cl)
- ~
E 8<ll Remediate WMA 1 and WMA 2 4 excavations to cleanup goals (and -, Perform Phase 1 final status surveys Q
<ll surface soil in selected areas) ~
0 Estimate potential annual dose from WMA 1 and WMA 2
~ excavated areas assuming unrestricted release of project premises , with combined exposure scenario Figure 5-6. General Dose Modeling Process
- Evaluating alternate conceptual models, including a residential gardener and a multi-source conceptual model for subsurface soil DCGLs, for comparison with the initial base-case models; Revision 2 5-18
WVDP PHASE 1 DECOMMISSIONING PLAN
- Evaluating the DCGLs produced by all of the modeling and determining the most limiting DCGLs for each radionucl ide of interest; Analyzing combined source area exposure scenarios;
- Considering the results of the ALARA analysis described in Section 6;
- Establishing cleanup goals (target levels below the DCGLs) to ensure that the degree of remediation in Phase 1 of the decommissioning will not limit Phase 2 options;
- Characterizing surface soil , subsurface soil , and streambed sediment as specified in Section 9; 5
- Refining the DCGLs and cleanup goals based on the resulting data ;
- Completing remediation of the WMA 1 and WMA 2 excavations and selected I surface soil areas to the cleanup goals;
- Performing Phase 1 final status surveys in the remediated Phase 1 areas, and
- Making estimates of the potential future doses for the remediated WMA 1 and I WMA 2 deep excavation areas using these data.
Note that use of a surrogate radionuclide such as Cs-137 to represent all radionuclides in a mixture of radionuclides is not practical at this time because available data are not sufficient to establish radionuclide distributions in environmental media. This matter is discussed further in Section 5.4.3.
5.2 OCGL Development This section provides the following information:
- Subsection 5.2.1 describes the conceptual models used for developing DCGLs for surface soil.
- Subsection 5.2.2 describes the conceptua l models used for developing DCGLs for subsurface soil.
- Subsection 5.2.3 describes the conceptual model used for developing DCGLs for streambed sediment.
- Subsection 5.2.4 describes the mathematical model (RESRAD) used to calcu late deterministic DCGLs for the various conceptual models.
5 The characterization to be performed as described in Section 9 will provide data on the depth and lateral extent of contamination that may be useful in better defining source geometry in the conceptual model. For example, if the actual stream bed and stream bank source geometry were found to be substantially different from that assumed in the conceptual model , then the conceptual model would be revised accordingly and the DCGLs recalculated . The same approach would be used for the subsurface soil DCGLs. However, there are no plans to recalculate surface soil DCGLs for this reason because the assumed one meter source th ickness is generally conservative and it is important to avoid changes to surface soil DCGLs that would impact the design of the Phase 1 final status surveys . While DCGLs are developed for 18 radionuclides ,
characterization data may indicate that some radionuclides may be dropped from further consideration. This could be the case, for example, if one or more of the 18 radionuclides do not show up above the minimum detectable concentration in any of the soil or sed iment samples.
Revision 2 5-19
WVDP PHASE 1 DECOMMISSIONING PLAN
- Subsection 5.2.5 provides the modeling results - the deterministic DCGLs - alorng with a discussion of these results..
- Subsection 5.2.6 describes sensitivity analyses performed.
- Subsection 5.2 .7 describes the probabilistic uncertainty analysis.
- Subsectiorn 5.2.8 describes the multi-source analysis for subsurface soil DCGLs that takes into account releases of iradioactivity from the bottoms of the deep excavations by dififu sion .
The DCGL development analyses simulate the behavior of residual radioactivity over 1000 years , a period during which peak annual doses from the rad ionuclides of primary interest would be expected to occur. DCGLs have been developed for residual radioactivity that will result in 25 mrem per year dose to the average member of the critical group for each of the following 18 radionuclides of interest:
Am-241 Cs-137 Pu-239 Tc-99 U-235 C-14 1-129 Pu-240 U-232 U-238 Cm-243 Np-237 Pu-241 U-233 Cm-244 Pu-238 Sr-90 U-234 Early studies related to the long-term performance assessment for residual radioactivity at the site included consideration of the initial inventory of radionuclides received on site and their progeny. This list was screened to eliminate short-lived radionuclides and those radionuclides present in insignificant quantities. Thirty radionuclides of interest remained after this screening process. These radionuclides were important to worker dose and/or long-term dose from residual radioactivity.
In characterization of radionuclides in the area of the Process Building , the north plateau groundwater plume , and the lagoons, it was determined that 18 of the 30 radionuclides were important for the development of Phase 1 DCGLs. These radionuclides were selected based on screening of simplified groundwater release and intrusion scenarios for north and south plateau facilities. The screening indicated that other radionuclides will in combination contribute less than one per cent of potential dose impacts at the individual facility.
The list of radionuclides for which DCGLs are initially developed will be expanded if necessary following completion of soil and sediment characterization described in Section
- 9. If other radionuclides show up in concentrations significantly above the minimum detectable concentrations, additional DCGLs will be developed for these radionuclides and their progeny, as appropriate . Conversely, if any of the 18 radionuclides of interest fail to show up in concentrations above the minimum detectable concentrations , then they may be omitted from the final DCGLs for the Phase 1 actions .
As explained in Section 1, the DCGLs for Sr-90 and Cs-137 were developed to incorporate a 30-year decay period from 2011 . That is, achieving residual radioactivity levels less than the DCGLs will ensure that dose criteria of 10 CFR 20.1402 will be met in Revision 2 5-20
WVDP PHASE 1 DECOMMISSIONING PLAN 2041 .6 Although a 30-year decay period could have been applied to all radionuclides, Sr-90 and Cs-137 were selected based on their prevalence in soil and sediment contamination, their expected peak doses at the onset of exposure, and the short half lives of these particular radionuclides .
5.2.1 Conceptual Models for Surface Soil DCGL Development The initial base-case - conceptual model for development of surface soil DCGLs is described first.
Surface Soil Conceptual Model (Base-Case)
Figure 5-7 illustrates the conceptual model for surface soil DCGL development. As is evident from this figure , which was adapted from the RES RAD Manual (Yu , et al. 2001 ), the basic RESRAD model is used .
Unsaturated Zone 2 m (6 ft) thick Cover depth and contaminated zone erosion rate = 0 Sand and Gravel Layer (Saturated Zone)
Well pump intake depth 5 m below water table I~
Lavery Till (Silty Clay)
Shale Bedrock Figure 5-7. Conceptual Model for Surface Soil DCGL Development 6
This approach will support any license termination actions that may take place in Phase 2 of the decommissioning. As noted previously, the decision on the Phase 2 decommissioning approach could be made with in 10 years of the Record of Decision and Findings Statement documenting the Phase 1 decisions. If this approach were to involve unrestricted release of the site, achieving this condition would be expected to take at least another 20 years due to the large scope of effort to exhume the underground waste tanks and the NOA. It is therefore highly unlikely that conditions for unrestricted release of the project premises could be established before 2041 . If Phase 2 were to involve closing radioactive facilities in place, then institutional controls would remain in place.
Revision 2 5-21
WVDP PHASE 1 DECOMMISSIONING PLAN RESRAD is a computer model designed to estimate radiation doses and risks from RESidual RADioactive materials (Yu , et al. 2001). DOE Order 5400.5 designates RESRAD for the evaluation of radioactively contaminated sites, and NRC has approved the use of RESRAD for dose evaluation by licensees involved in decommissioning . RESRAD capabilities are discussed further in Section 5.2.2 .
A resident farmer is the average member of the critical group for development of surface soil DCGLs. The hypothetical residence and farm are assumed to be located on a part of the project premises impacted solely by radioactivity in surface soil.
Other possible critical groups were considered . However, a resident farmer was assumed to be most limiting because such an individual would be engaged in a wider range of activities that could result in greater exposure to residual radioactivity in surface soil than other critical groups considered . (Tlhis assumption was confiirmed by evaluation of alternate conceptual models involving erosion and a residential gardener as discussed below.)
The resident farmer would be impacted by a number of exposure pathways with long exposure durations. This hypothetical individual would utilize significant amounts of groundwater that involves consideration of secondary exposure pathways such as household water use , irrigation , and watering livestock. The resident farmer scenario also is consistent with current and projected future land uses for Cattaraugus County as discussed in Section 3.
Note that the geological units shown in Figure *5-7 are representative models of the north plateau as shown in Figure 3-6. Figure 3-7 shows that the geological units on the south plateau are different in that the sand and gravel unit does not extend to that area .
However, DCGLs developed using the conceptual model illustrated in Figure 5-7 are appropriate for surface soil on the south plateau because the input parameters used in the modeling for the north plateau will generally be conservative for the south plateau . For example, site-specific distribution coefficients for the sand and gravel unit (where available) are typically lower than those for the Lavery till, and use of the lower values results in less resistance to radionuclide movement though soil , allowing less time for radioactive decay to 7
take place.
Table 5-2 shows the exposure pathways evaluated for development of the surface soil DCGLs.
7 Table C-2 of Appendi x C shows that site-specific Kd values for neptunium , plutonium , and strontium in the sand and gravel un it are used in the surface soil model. Table 3-20 of shows the basis for these values . The' use of lower Kci values than those in south plateaus soil is conservative for water pathways, but may not be conservative for plant uptake and direct exposure pathways. However, the model would be conservative for south plateau conditions for most radionuclides.
- Revision 2 5-22
WVDP PHASE 1 DECOMMISSIONING PLAN Table 5-2. Exposure Pathways for Surface Soil DCGL Development Exposure Pathways Active External gamma radiation from contaminated soil Yes Inhalation (airborne radioactivity from re-suspended contaminated soil) Yes Plant ingestion (produce impacted by contaminated soil and groundwater Yes sources)
Meat in gestion (beef impacted by contaminated soil and groundwater sources) Yes Milk ingestion (impacted by contaminated soil and groundwater sources) Yes Aquatic food ingestion No(1)
Ingestion of drinking water (groundwater impacted by contaminated soil) Yes Ingestion of drinking water (from surface water)(2) No Soil ingestion (while farming and residing on contam inated soil) Yes Radon inhalation No(3)
NOTES: (1) Fish ingestion is considered in development of the streambed sediment DCGLs and in the combined scenario discussed in Section 5.3.
(2) Groundwater was assumed to be the source of all drinking water because the low flow volumes in Erdman Brook and Franks Creek could not support the resident farmer. Also , use of surface water would not be as conservative as groundwater since surface water is diluted by* runoff from the entire watershed area . Incidental ingestion of water from the streams is evaluated in development of the streambed sediment DCGLs as shown in Table 5-6.
(3) For the standard resident farmer scenario, the radon pathway is not considered (Appendix J, NRC 2006).
RESRAD requires a variety of input parameter values to completely describe the conceptual model. All of the input parameters for development of the surface soil DCGLs appear in Appendix C. Table 5-3 identifies selected key input parameters.
Table 5-3. Key Input Parameters for Surface Soil DCGL Development(1J Parameter (Units) Value Basis 2
Area of contaminated zone (m ) 1.0E+04 Necessary for subsistence farming.
Thickness of contaminated zone (m) 1.0E+OO Conservative assumption .(2)
Cover depth (m) 0 Contamination on surface.
Contaminated zone erosion rate (m/y) 0 Conservative assumption .P)
Well pump intake depth below water table (m) 5.0E+OO Consistent with water table.
Well pumping rate (m 3/y) 5.72E+03 See Table C-2 .
Unsaturated zone thickness (m) 2.0E+OO Typical for north plateau .
Distribution coefficient for strontium (mUg) 5.0E+OO See Table C-2 .
Distribution coefficient for cesium (ml/g) 2.8E+02 See Table C-2 .
Distribution coefficient for americium (ml/g) 1.9E+03 See Table C-2.
NOTES: ( 1) See Appendix C for other input parameters. Metric units are used here because they are normally used in RESRAD.
Revision 2 5-23
WVDP PHASE 1 DECOMMISSIONING PLAN (2) Available data discussed in Sections 2.3.2 and 4.2 suggest that most contamination will be found within a few inches of the surface except where the north plateau groundwater plume has impacted subsurface soil. Tlile one meter thi ckness is an appropriat e compromi se for the set of radion uolides of interest whose primary dose pathways range from direct ex posure, to groundwater ingestion, \to plant uptake.
(3) This assumption is conservative because it results in no depletion of the source through erosion.8 Key features of this conceptual model and key assumptions include:
- The areal extent of surface soil contamination , which has not been well defined ,
can be represented by a distributed source spread over a relatively large area (10 ,000 square meters or approxi mately 2.5 acres);
- The average depth of contamination (contamination zone thickness) is approximately 3.3 feet (one meter), a conservative assumption for the site ;
- Because the model considers only surface contamination, the resulting DCGLs and cleanup goals are applicable only to portions of the project premises where there is no subsurface contamination (i .e., contamination does not extend beyond a depth of 1 meter);
- All water use (e.g ., household , crop irrigation , and livestock watering) is from contam inated groundwater;
- Adequate productivity from a well pumping from the aquifer will be available in the future to support a subsistence farm ;
- Soil erosion (i.e., source depletion) does not occur over the 1,000-year modeling period;
- The non-dispersion groundwater model is used because of the large contaminated area consistent with applicable guidance (Yu, et al. 2001 , Appendix E);
- The groundwater flow regime under the post-remedial conditions is unchanged from the current configuration (e.g. flow direction, aquifer productivity); and
- DCGLs that reflect 30 years of decay (i.e., apply to the year 2041) are appropriate for Sr-90 and Cs-137. Although a 30-year decay period could have been applied to all radionuclides , Sr-90 and Cs-137 were selected based on their prevalence in surface soil , their expected peak doses at the onset of exposure, and the short half lives of these particular radionuclides , as noted previously.
Alternate Conceptual Model for Surface Soil DCGLs (Erosion, Offsite Receptor)
Other conceptual models were considered, even though the resident farmer model with its many exposure pathways is generally considered to be the most conservative model. To 8
The conservative nature of the assumption can be demonstrated by assuming that erosion takes place and evaluating potential doses to a receptor located in a gully where rad ioactivity has been displaced by erosion .
As explained in the discussion of alternate conceptual models below, the receptor in the area of the gully would receive less dose on an annual basis than would the resident farmer due to factors such as source dilution, spending less time in the contaminated area, and receiving exposure through fewer pathways .
Consideration of potential doses to an offsite receptor from rad ioactivity displaced to the stream through erosion indicates that there is a reasonable expectation that offsite doses would not be significant either.
Revision 2 5-24
WVDP PHASE 1 DECOMMISSIONING PLAN confirm that the assumption of no erosion in the contamination zone (one of the key parameters in Table 5-3) is conservative, an analysis was performed to estimate the potential doses to an offsite receptor from radioactivity that could be released from the hypothetical garden used in the base-case model through erosion .
In this analysis, eroded soil was assumed to be transported in surface water to a receptor located on Cattaraugus Creek near the confluence with Buttermilk Creek who ingested both the water and fish harvested from the water and used the water to irrigate a garden . The results showed that doses to this receptor would be insignificant.
Alternate Conceptual Model for Surface Soil DCGLs (Residential Gardener)
Another alternative exposure scenario was evaluated to confirm that the base-case resident farmer scenario is bounding for development of surface soil DCGLs. This alternative scenprio involved a residential gardener scenario.
The receptor in the residential gardener scenario is a hypothetical person who resides in the area and grows a vegetable garden. This scenario differs from the resident farmer scenario in that the person of interest does not consume meat or milk produced on the property and spends less time outdoors in the hypothetical garden. The well pumping rate used in this scenario was lower than that used in the resident farmer model (1140 cubic meters per year compared to 5720 meters per year) to reflect the smaller garden being used and the lower well water usage.
This alternative exposure scenario produced DCGLs that were slightly higher than those produced by the base ~case resident farmer model for all 18 radionudides.
Consequently, the base-case model is bounding for surface soil DCGL development when compared to the residential gardener scenario. (See Section 5.2.7 for the results of the probabilistic uncertainty analysis.)
Revision 2 5-25
WVDP PHASE 1 DECOMMISSIONING PLAN 5.2.2 Subsurface Soil Conceptual Models Evaluation of Various Subsurface Soil Conceptual Models The analyses described in Revision 0 and Revision 1 to this plan made use of the base-case conceptual model for subsurface soil DCGL development described below and illustrated in Figure 5-8. Minor changes were made to this conceptual model in Revision 2 that produced DCGLs that were slightly higher for most radionuclides.
Additional analyses were also performed to determine whether this conceptual model, which makes use of the resident farmer scenario, represented the bounding case for potential future doses from the remediated deep excavations. These additional analyses, which are described below, involved:
- Evaluating the potential acute dose to the hypothetical individual drilling the well (the two meter diameter cistern) used in the original base case model,
- Evaluating potential acute dose to a hypothetical individual who might drill a natural gas well in the area of one of the deep excavations,
- Evaluating potential doses to a recreational hiker in the area of the lagoons in WMA 2 assuming that unchecked erosion would eventually produce deep gullies in this area,
- Evaluating potential doses to an offsite receptor from residual radioactivity at the bottom of the deep excavation in WMA 2 that might be released to Erdman Brook if deep gullies were to eventually cut into this area, and
- Evaluating a residential gardener scenario.
Of these five alternate conceptual models, one, the residential gardener model , was found to be more limiting for some radionuclides than the original base-case resident farmer scenario .
To help determine whether the input parameters used in the original base-case model were sufficiently conservative, a comprehensive probabilistic uncertainty analysis was performed (similar analyses were also performed for surface soil and streambed sediment DCGL development). Section 5.2. 7 describes this analysis. The resulting peak-of-the-mean DCGLs were somewhat lower for most radionuclides than the DCGLs produced by the deterministic resident farmer and residential gardener scenarios.
Another analysis was performed to evaluate whether continuing release of residual radioactivity from the bottom of the deep excavations would influence potential future doses from the remediated deep excavations. Section 5.2.8 describes this analysis. The original base-case conceptual model was modified to add a secondary source of radioactivity from residual contamination at the bottom of the deep excavation that moves upward by diffusion and is drawn into the hypothetical well , resulting in additional dose to the resident primarily from the drinking water pathway.
This multi-source model was analyzed using the resident farmer scenario and also the residential gardener scenario, the latter with three different upper contamination zone geometries to evaluate the sensitivity of the model to the contamination zone area and thickness. The results showed that this model was more limiting for nine of the 18 radionuclides of interest than the other subsurface soil DCGL conceptual models that were evaluated.
Consideration of the results of all of this subsurface soil dose modeling led to the decision to use the lowest DCGLs among all of the modeling results as the basis for the subsurface soil cleanup goals in the interest of conservatism .
Revision 2 5-26
WVDP PHASE 1 DECOMMISSIONING PLAN In itial Base-Case Conceptual Model Figure 5-8 illustrates the initial base-case conceptual model for subsurface soil DCGL development. The basic RESRAD model is used as with development of surface soil DCGLs , with a resident farmer being the average member of the critical group . The hypothetical residence and farm are assumed to be located in the remediated WMA 1 area.
Exposure to the subsurface radioactivity occurs following intrusion and surface dispersal when installing a water collection cistern .
The contaminated zone is garden soil in a 100 m2 area 0.3 m thick, r A resident farmer is the average member of the critical group.
Hypothetical cistern (2 m diameter well ,
10 m deep)
Uncontaminated backfill, unsaturated zone (2 m thick)
Uncontaminated backfill, saturated zone Well (cistern) intake depth 5 m below water table Contamination on bottom of excavation in area where cistern is installed is brought to surface Residual Radioactivity at Bottom of Excavation (Lavery Till)
Lavery Till (Silty Clay)
Shale Bedrock Figure 5-8. Conceptual Model for Subsurface Soil DCGL Development Other possible critical groups were considered as with the conceptual model for surface soil DCGLs. However, a resident farmer was initially assumed to be most limiting because such an individual would be engaged in a wider range of activities that could result in greater exposure to residual radioactivity in subsurface soil than other critical groups considered .
Revision 2 5-27
WVDP PHASE 1 DECOMMISSIONING PLAN Consideration was given to a home construction scenario with the basement in the hypothetical home extending 10 feet below the surface . However, this scenario was not considered to be plausible because any contaminated subsurface soil will be more than 10 feet below the surface in the remediated WMA 1 and WMA 2 areas (the bottoms of the excavations will be more than 10 feet below the surface and uncontaminated soil will be used to backfill the excavations).
Note that Section 7 specifies that the uncontaminated backfill as shown in the figure will be soil obtained from outside of the Center from an area that has not been impacted by site radioactivity. No soil removed during the excavation work will be used in filling the excavation, even if that soil were determined to be uncontaminated .
Consideration of NRC Guidance Related to Buried Radioactivity Also considered in development of this conceptual model was NRC guidance related to assessment of buried radioactivity in Appendix J to NUREG-1757, Volume 2 (NRC 2006). This guidance applies to cases where radioactive material is buried deep enough that an external dose is not possible in its existing configuration ; any radioactivity remaining at the bottom of the WMA 1 and WMA 2 excavations would meet this condition , and the WVDP situation is consistent with the intent of the guidance.
The NRC notes that a conservative analysis could be performed that assumes all of the material is spread on the surface . It describes two alternative exposure scenarios: ( 1) leaching of the radionuclides to groundwater, which is then used by a residential farmer, and (2) inadvertent intrusion into the buried radioactive material , with part of the radioactivity being spread across the surface where this fraction causes exposure to a resident farmer through various pathways. NRC further notes that "The second alternative exposure scenario encompasses all the exposure pathways and , although not all of the source term is in the original position , leaching will occur both from the remaining buried residual radioactivity (if there is any) and the surface soil. Unless differences in the thickness of the unsaturated zone will make a tremendous difference in travel time to the aquifer, the groundwater concentrations should be similar and , therefore, will generally result in higher doses than the first alternate scenario."
The surface soil DCGLs discussed previously represent the case where all of the radioactive material of interest is located on the ,surface; as explained in Section 6, possible application of these DCGLs to the subsurface soil of interest would be addressed in the ALARA analysis. DOE has selected the second alternative exposure scenario - inadvertent intrusion into the buried material , that is, into any residual radioactivity at the bottom of the WMA 1 and WMA 2 excavations - as the basis for development of the subsurface soil DCGLs. NRC discusses in Appendix J to NUREG-1757 (NRC 2006) the use of RESRAD in analysis of the inadvertent intrusion scenario ,
which DOE has implemented here.
Note that a combination of inadvertent intrusion and continuing releases from the bottoms of the remed iated deep excavations was also evaluated in the multi-source conceptual model as described in Section 5.2.8, Revision 2 5-28
WVDP PHASE 1 DECOMMISSIONING PLAN This conceptual model has the following features , some of which are indicated on Figure 5-8
- The initial modeled source of contamination brought to the surface consists of residual radioactivity in an area two meters (about six feet) in diameter and one meter (about three feet) thick, the top surface of which lies nine meters (about 30 feet) below the ground surface. The contamination assumed to be in this volume of subsurface soil represents the residual radioactivity of interest at the bottom of the WMA 1 or WMA 2 excavation . The exposure occurs when the subsurface radioactivity is deposited on the ground surface where it can result in exposure to members of the critical group through various pathways .
- For conservatism the hypothetical well is assumed to have a large diameter representative of a cistern , rather than the smaller diameter of a typical water supply well (eight inches). The larger diameter provides for a greater volume of contamination being brought to the surface, and is therefore conservative compared to the typical well diameter.
- The nine meters (about 30 feet) of uncontaminated backfill above the initial source of contamination com ingles with the contam inated soil, and the mixture is assumed to uniformly cover a cultivated garden area of 100 square meters (about 1000 square feet) , i.e., a small portion of the 10,000 square meter garden , to a depth of 9
0.3 meter (one foot) .
- The remainder of the contamination in the bottom of the excavation was not modeled as a continuing source to groundwater because this source is located below the assumed well pump intake depth and was not expected to leach upward into the source of water available to the resident farmer. (However, additional analysis showed that doses from continuing releases from the contamination at the bottom of the excavation would be significant for some rad1onuclides as described in Section 5 .2.8.)
Table 5-4 shows the exposure pathways for development of the subsurface soil DCGLs, which are the same as for the surface soil DCGLs.
Table 5-4. Exposure Pathways for Subsurface Soil DCGL, Development Exposure Pathways Active External gamma radiation from contaminated soil Yes Inhalation of airborne radioactivity from re-suspended contaminated soil Yes Plant ingestion (produce impacted by contaminated soil and groundwater Yes contaminated by impacted soil)
Meat ingestion (beef impacted by contaminated soil and groundwater Yes contam inated by impacted soil)
Milk ingestion (impacted by contaminated soil and groundwater contaminated Yes by impacted soil)
~~~~~~~~~~~~~~~~~~~~~~~~~-+-~~~-fl Aquatic food ingestion 9
Note that larger contamination zone areas were evaluated in the multi-source conceptual model described I in Section 5.2.8 Revision 2 5-29
WVDP PHASE 1 DECOMMISSIONING PLAN Table 5-4. Exposure Pathways for Subsurface Soil DCGL Development Exposure Pathways Active Ingestion of drinking water {from groundwater contaminated by impacted soil) Yes 2
Ingestion of drinking water (from surface water)< ) No Soil ingestion Yes Radon inhalation No<3)
NOTES: (1) Fish ingestion is considered in development of the streambed sediment DCGLs and in the combined scenario discussed in Section 5.3.
(2) Groundwater was assumed to be the source of all drinking water because the low flow volumes in Erdman Brook and Franks Creek could not support the resident farmer. Use of surface water would also not be as conservative as groundwater since surface water is diluted by runoff from the entire watershed area . Incidental ingestion of water from the streams is evaluated in development of the streambed sediment DCGLs as shown in Table 5-6.
(3) In using the standard resident farmer scenario in modeling of buried radioactivity, the radon pathway is not considered (Appendix J, NRC 2006).
All of the input parameters for development of the subsurface soil DCGLs appear in Appendix C. Table 5-5 identifies selected key input parameters .
Table 5-5. Key Input Parameters for Subsurface Soil DCGL Development<1J Parameter (Units) Value Basis Initial source - cistern diameter (m) 2.0E+OO Conservative values used Initial source - depth below surface (m) 9.0E+OO to estimate radioactivity brought to the surface to be Initial source - thickness (m) 1.0E+OO mixed in garden soil.
Area of contaminated zone (m 2 ) 1.0E+02 Area drill cuttings from cistern installation spread on surface.
Thickness of contaminated zone (m) 3.0E-01 Contaminated soil depth in garden.
Cover depth (m) 0 Contamination on surface.
Contaminated zone erosion rate (m/y) 0 Conservative assumption .< 2)
Well pumping rate (m 3/y) 5.72E+03 See Table C-2.
Unsaturated zone thickness (m) 2.0E+OO Reasonable for WMA 1 and WMA2 .
Distribution coefficient for strontium (ml/g) 1.5E+01 See Table C-2.
Distribution coefficient for cesium (ml/g) 4.8E+02 See Table C-2 .
Distribution coefficient for americium (ml/g) 4.0E+03 See Table C~2 .
NOTES: ( 1) See Appendix C for other input parameters. Metric units are used here because they are normally used in RESRAD .
10 (2) This assumption is conservative because it results in no depletion of the source.
10 The conservative nature of the assumption can be demonstrated by assuming that erosion takes place and evaluating potential doses to a receptor located in a gully where radioactivity has been exposed by erosion . As explained in the discussion of alternate conceptual models below, the receptor in the area of the gully would receive less dose on an annual basis than would the resident farmer due to factors such as spending less time in the contaminated area and receiving exposure through fewer pathways. Consideration of potential doses to an offsite receptor from radioactivity displaced to the stream through erosion indicates that there is a reasonable expectation that offsite doses would not be significant either, as discussed below.
Revision 2 5-30
WVDP PHASE 1 DECOMMISSIONING PLAN Key assumptions associated with this conceptual model include:
- Contamination in the bottom one meter of the 10 meter deep excavation of the two meter diameter cistern would be brought to the surface, along with the overlying uncontaminated backfill, and blended into the soil over a 100 square meter area used by the resident farmer.
- All water used by the resident farmer (e.g., household , crop irrigation , and livestock watering ) is groundwater wh ich has been impacted by leaching of contaminants from surface soil (distributed excavated material) via infiltration of precipitation and irrigation water;
- Surface soil erosion (i. e., source depletion ) does not occur over the 1,000 year-modeling period ;
- The groundwater flow regime under the post-remedial conditions is unchanged from the current configuration (e.g. flow direction , aquifer productivity); and
- DCGLs that reflect 30 years of decay (i.e., apply to the year 2041) are appropriate for Sr-90 and Cs-137. Although a 30-year decay period could have been applied to all radionucl ides, Sr-90 ad Cs-137 were selected based on expected peak doses at the onset of exposure and the short half lives of these particular rad ionuclides. as noted previously .
.Alternate Conceptual Model for Subsurface Soil DCGLs (Cistern Well Driller)
A drilling worker scenario evaluates dose to a hypothetical individual installing the cistern , such as from contamination brought to the surface in the form of drill cuttings that could be set aside near the cistern. A well driller scenario was evaluated using RESRAD with conservative assumptions. Key elements in the model inoluded :
- The drilling worker being exposed to excavated Lavery till material from the bottom of the excavation that was deposited on top of uncontaminated soil in the vicinity of the cistern for a 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> period, even though the actual exposure period would likely be much shorter;
- The contamination zone being nine square meters in area and 0.333 meters thick, based on an excavated volume of three cubic meters of contaminated Lavery till material; and
- An assumption of no water shielding, even though water in a cuttings pond would typically provide shielding from direct radiation.
The exposure pathways considered included inadvertent ingestion of contaminated soil , inhalation of contaminated dust, and direct exposure to contaminated soil brought to the surface during the drilling . The resulting DCGLs, which are shown in Table 5-11c in Section 5.2.8, were greater than the subsurface soil DCGLs for all radionuclides developed for the resident farmer scenario, indicating the well driller scenario is less limiting that the resident farmer scenario used in developing the subsurface soil DCGLs.
Revision 2 5-31
WVOP PHASE 1 DECOMMISSIONING PLAN Altennate Conceptual Model for Subsurface Soil DCGLs (Erosjon, Ons'ite Receptor)
An alternate conceptual model was evaluated involving the potential impact of unchecked erosion in WMA 2 to an onsite receptor. The model assumed that gully erosion would produce narrow, deep steep-sided gullies, cond itions where building a home and growing crops would not be practical. A plausible scena ri o for these conditions would involve a recreationist spendirng time hiking i n the area , wh ich is assumed to be rent by deep gullies that extend to the bottom of the WMA 2 excavation. Figure 5-9 illustrates the basic conceptual model. This scenario was analyzed using RES.RAD in the deterministic mode.
Approximate Feet Above Mean Sea Level 1370 1365 1360
. .. * . * .*. *.: * ** *** * .. *... .. .. .. . : : zone at excavation bottom 1355 .;. : .:-:::: : : : : >:: : : : :: : : : (modeled as a single source area)
Figure 5-9 Recreationist Conceptual Model Cross Section The modeling of this recreationist scenario produced DCGLs for 25 mrem per year that were more than one order of magnitude greater than the DCGLs produced with the initial base-case resident farmer/cistern scenario for all 18 radionuclides of interest as shown in Table 5-11 c in Section 5.2.8. These results demonstrate that the resident farmer/cistern scenario is more limiting for an onsite receptor.
Alternate Conceptual Model for Subsurface Soil DCGLs (Erosion, Offsite Receptor)
Another alternative scenario was evaluated to determine the potential impact of long-term erosion in WMA 2 to an offsite receptor. This analysis estimated the potential doses to an offsite receptor from radioactivity that could be released from the bottom of the remediated WMA 2 excavation due to formation of a gully that eventually cut through the bottom of the backfilled excavation.
In this analysis, radioactivity in eroded soil from the bottom of the WMA 2 backfilled excavation was assumed to be transported in surface water to a receptor located on Cattaraugus Creek near the confluence with Buttermilk Creek who ingested both the water and fish haNested from the water and used the water to irrigate a garden . Both the area of Lagoon 1 and the area of Lagoon 3 were considered using conseNative erosion rates. The results showed that doses to this receptor would be insignificant compared to the onsite receptor doses estimated in the base-case resident farmer model. Table 5-11c below shows the DCGLs calculated for the Lagoon 3 area .
Revision 2 5-32
WVDP PHASE 1 DECOMMISSIONING PLAN Alternate Conceptual Model for Subsurface Soil DCGLs (Natural Gas Well Driller)
Installation of a natural gas well was also evaluated. Installation of thi s type of well would take longer than installation of a cistern because the well would be much deeper, would require well/formation development by hydrofracturing , and would require the installation of conveyance piping and valving. The arnalysis focused on exposure to the drilling worker. Key elements in the model 1included:
- The natural gas well being 0.5 meter (20 inches) in diameter and 100 meters {330 feet) deep (a conservative estimate given typical depths in excess of 1,000 meters); and
- The drilling worker being exposed to excavated Lavery till material from the bottom of the excavation that was deposited in a cuttings pit near the worker's location for 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />.
The exposure pathways considered included inad_ vertent ingestion of contaminated soil, inhalation of contaminated dust, and direct exposure to contaminated soil brought to the surface during the drilling . RESRAD version 6.4 in the deterministic mode was used to perform the calculations. The resulting DCGLs shown in Table 5-11c below were one or more orders of magnitude greater than the determ inistic base-case resident farmer subsurface soil DCGLs for all radionuclides, demonstrating that the base-case resident farmer-cistern installation scenario is more limiting .
Alternate Gonceptual Model for Subsurface Soil DCGLs (Residential Gardener)
Another alternative exposure scenario was evaluated to determine whether the base-case resident farmer-cistern installation scenario was bounding for development of subsurface soil DCGLs. This alternative scenario involved a residentia l gardener scenario.
The receptor in the residential gardener scenario is a hypothetical person who resides in the area and grows a vegetable garden . This scenario differs from the resident farmer scenario in that the person of interest does not consume . meat or milk produced on the property and spends less time outdoors in the hypothetical garden . The well pumping rate used in this scenario was lower than the rate used in the resident farmer model (1140 cubic meters per year compared to 5720 meters per year) to reflect the smaller area being used and the lower well water usage.
This analysis was performed using three models which differed with respect to the area of the contamination zone and its thickness:
- Model 1 used a 100 square meter area and 0.3 meter depth, the base-case values in the base-case resident farmer deterministic analysis;
- Model 2 used a 300 square meter area and 0.1 meter depth ; and
- Model 3 used a 50 square meter area and 0.6 meter depth; This alternative exposure scenario pmduced DCGLs for some radionuclides that were lower than those produced by the base-case resident farmer model. In most cases , Model 2 with the largest contamination zone area produced the lowest DCGLs due to higher groundwater concentrations from reduced dilution and larger contaminated fractions from ingestion pathways. The results appear in Section 5.2.8 and were taken into account in establishing revised cleanup goals.
Revision 2 5-33
WVDP PHASE 1 DECOMMISSIONING PLAN 5.2.3 Streambed Sediment Conceptual Model Figure 5-10 illustrates the conceptual model for development of stream bed sediment DCGLs. Table 5-6 identifies the exposure pathways considered.
r A recreationist fishing , hunting, and hiking in the stream area is the average member of the critical group.
~-
ITypical streambed contour
- ~~~------.
The contaminated zone is assumed to be 1 meter (3 feet) thick.
Figure 5-10. Conceptual Model for Streambed DCGLs-Development Table 5-6. Exposure Pathways for Streambed Sediment DCGL Development Exposure Pathways Active External gamma radiation from contaminated sediment Yes Inhalation of airborne radioactivity from resuspended contaminated No<1l sediment Plant ingestion (produce impacted by soil and water sources) No Meat ingestion (venison impacted by soil and water sources) Yes Milk ingestion (impacted by soil and water sources) No Aquatic food ingestion (fish) Yes Ingestion of drinking water (from groundwater well) No Ingestion of drinking water (incidental from surface water) Yes Sediment ingestion (incidental during recreation) Yes Radon inhalation No<2 l NOTES: (1) Sediments adjacent to streambed have significant moisture content that inhibits their resuspension potential, which would minimize inhalation exposure. Additionally, vegetation along the streambed will likely preclude significant wind scour and subsequent inhalation . To confirm these conclusions ,
the model was revised to include the inhalation pathway as well as to make other minor refinements; these changes did not produce a significant difference in the results.
(2) The radon pathway is not considered because radon is primarily naturally occurring and neither radon nor its progeny are among the rad ionuclides of significant interest in dose modeling .
Revision 2 5-34
WVDP PHASE 1 DECOMMISSIONING PLAN The conceptual model for streambed sediment was developed after consideration of how residual radioactivity enters and moves though the streams, plausible future land uses for the stream valleys, how humans might be exposed to residual contamination in the streams or on the banks, and plausible habits of a person who might spend time at the streams in the future . Such considerations led to selection of a conceptual model compatible with RESRAD. The RESRAD code was determined to be an appropriate mathematical model based on its extensive use in evaluating potential doses from radioactivity in surface soil and its use in the surface soil DCGL and subsurface soil DCGL models for th is project As shown in Figure 5-10 , the contamination zone was assumed to be on the stream bank rather than in the stream itself. This model is consistent with typical conditions observed along Frank's Creek downstream of the Lagoon 3 outfall as shown by the radiological control area in Figure 5-11 represented by the roped-off area. It is conservative compared to having the contamination zone in the stream itself where water would act as shielding to reduce the direct radiation dose.
The photograph in Figure 5-11 was taken from just inside the project premises security fence looking upstream toward the southwest. The confluence with Erdman Brook lies about 200 feet upstream from where the people are standing and the Lagoon 3 outfall .is about 500 feet from where the people are standing .
Figure 5-11. Franks Creek Looking Upstream (2008 WVDP photo)
Key features of this conceptual model include the following :
- A person spending time in the area of the streams for recreation purposes was determined to be the appropriate member of the critical group; the area is not suitable for farming , livestock grazing , or residential use because of the steep Revision 2 5-35
WVDP PHASE 1 DECOMMISSIONING PLAN stream banks, especially considering further erosion that is likely to occur as discussed previously.
- In this exposure scenario the primary radiation source is considered as the sediment deposited on the stream bank. The ability of sediment to adsorb and absorb rad ionuclides would be expected to concentrate otherwise dilute species of ions from the water (NRC 1977). The water in the stream provides some shielding and separation from radionuclides in sediments on the stream bottom , thus 11 reducing direct exposure and incidental ingestion pathways from those sources.
- The hypothetical recreationist is assumed to be located on the contaminated stream bank for 104 hours0.0012 days <br />0.0289 hours <br />1.719577e-4 weeks <br />3.9572e-5 months <br /> per yea r, which could involve spending two hours per day, two days per week for 26 weeks a year, reasonable assumptions considering the local climate .
- The contaminated zone of interest is located on the stream bank and is assumed to be three meters (10 feet) wide and 333 meters (1093 feet) long, with a total area of 1000 square meters (approximately 1;'4 acre).
- Having the contaminated zone on the stream bank takes into account a situation where the stream level might rise significantly then fall again to a lower level.
- The hypothetical recreationist is assumed to eat venison from deer whose flesh is contaminated with radioactivity from contaminated stream banks , such as from grazing on grass, and ingesting stream water.
Consideration was given to both receptor location and stream bank geometry.
Potential doses to a recreationist from impacted stream water will be less significant than potential doses from the stream bank for the following reasons :
- It would be plausible for the hypothetical recreationist to spend more time on the stream bank than immersed in stream water;
- The water would provide radiation shielding for radioactivity in the streambed sediment, which would decrease potential dose from direct radiation ;
- While on the stream bank, the external dose from surface water would be negligible compared with the dose from the stream bank source; and
- Neglecting erosion of the stream bank source leads to greater doses than considering erosion of the source from the stream bank to the streambed, where significant shielding from surface water would reduce the dose.
The stream bank geometry was assumed to be represented by a plane source of contam ination along the stream bank. Potenti al doses from alternative source configurations were not included in th is evaluation for the following reasons :
11 Note that modeling of transport, deposition , and concentrations of rad ionuclides in the stream itself would require assumptions on potential releases after Phase 1 of the decomm issioning, and involve consideration of the Phase 2 end-state, factors whi ch are appropriately not considered at this time.
Revision 2 5-36
WVDP PHASE 1 DECOMMISSIONING PLAN
- Any dose variation due to a sloped stream bank would likely result in doses similar to level sources due to movement of the receptor and exposure to an equivalent uniform dose (e.g. receptor is assumed to spend time moving throughout the source area and facing all directions for equal amounts of time);
- Although exposure to a source area wider than several meters is unlikely considering the steep terrain, the receptor is assumed to be externally exposed to a circular infinite plane source for conservatism; and
- Because the mass balance model was used for the sediment calculations , the source width parameter is not used in the calculations for water dependent pathways.
All of the input parameters for development of the stream bed sediment DCGLs appear in Appendix C. Table 5-7 identifies selected key input parameters.
1 Table 5-7. Key Input Parameters for Streambed Sediment DCGL Development( >
Parameter (Units) Value Basis 2
Area of contaminated zone (m ) 1.0E+03 Area on stream bank.
Thickness of contaminated zone (m) 1.0E+OO Conservative assumption .
Fraction of year spent outdoors 1.2E-02 104 hours0.0012 days <br />0.0289 hours <br />1.719577e-4 weeks <br />3.9572e-5 months <br /> (out of a total of 8760 hours0.101 days <br />2.433 hours <br />0.0145 weeks <br />0.00333 months <br /> per year) in area .
Cover depth (m) 0 Contamination on surface.
Contaminated zone erosion rate (m/y) 0 Conservative assumption .'2 >
Well pump intake depth (m below water table) 0 Only applicable to farming .
3 Well pumping rate (m /y) 0 Only applicable to farming .
Unsaturated zone thickness (m) 0 Contamination on stream bank surface.
Contaminated zone distribution coefficient for 1.5E+01 See Table C-2 .
strontium (ml/g)
Contaminated zone distribution coefficient for 4.8E+02 See Table C-2 .
cesium (ml/g)
Contaminated zone distribution coefficient for 4.0E+03 See Table C-2.
americium (ml/g)
NOTES : (1) See Appendix C for other input parameters. Metric units are used here because they are normally used in RESRAD .
(2) This assumption is conservative because it results in no erosion of the source .
In development of the conceptual model , consideration was given to protection of environmental and ecological resources , as well as human health . It was determined that Revision 2 5-37
WVDP PHASE 1 DECOMMISSIONING PLAN no changes to the model or the radioactivity cleanup criteria will be necessary for this 12 purpose .
5.2.4 Mathematical Model As noted previously, RESRAD (Yu, et al. 2001) is used as the mathematical model for DCGL development. Version 6.4 was used to calculate the unit dose factors (in mrem/y per pCi/g) for each of the 18 radionuclides in each of the three exposure scenarios . Unit dose factors were then scaled in Microsoft Excel to calculate individual radionuclide DCGLs corresponding to 25 mrem per year.
RESRAD was selected as the mathematical model for DCGL development due to the extensive use by DOE and by NRC licensees in evaluating doses from residual radioactivity at decommissioned sites . The RESRAD model considers multiple exposure pathways for direct contact with radioactivity, indirect contact, and food uptake, which are the conditions being evaluated at the WVDP.
RESRAD was used with the post-Phase 1 conceptual models described previously to generate doses for unit radionuclide source concentrations (i.e. , dose per pCi/g of source).
The resulting doses were then scaled to the limiting acceptable dose (25 mrem in a year) to provide the rad ionuclide specific DCGLs (see Appendix C). For example, the maximum estimated annual dose from 1 pCi/g of Cs-137 in surface soil was determined to be 1.7 mrem , so the DCGL for 25 mrem per year is 25 divided by 1.7 or 14.8 pCi/g prior to accounting for decay (see Table C-5). The calculated DCGLs were then input into the model as the source concentration to verify that the dose limit of 25 mrem per year was not exceeded.
Among the general considerations for the application of RESRAD to the post-Phase 1 decommissioning conceptual models were :
- Use of the non-dispersion groundwater pathways model for surface soil due to the relatively large source area;
- Use of the mass balance model, instead of the less conservative non-dispersion model , for the subsurface and streambed sediment models due to the relatively small source areas; and 12 DOE Order 450.1 , Environmental Protection Program , requires that DOE Environmental Management facilities such as the WVDP have an environmental management system to ensure protection of the air, water, land , and other natural and cultural resources in compliance with applicable environmental ; public health; and resource protection laws, regulations, and DOE requirements . Implementing guidance includes DOE Standard 1153-2002 , A Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota. This guidance includes the use of biota concentration guides to evaluate potential adverse ecological effects from exposure to radionu clides.
The WVDP routinely evaluates potential annual doses to aquatic and riparian animals and plants in relation to the biota concentration guides using the RESRAD-BIOTA computer code (DOE 2004) and radionuclide concentrations measured in water and streambed sediment. These evaluations show compliance with the guides (WVES and URS 2009 ). The environmental monitoring and control program for Phase 1 of the decommissioning described in Section 1.8 would ensure compliance with DOE Order 450 .1 during the decommissioning activities.
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- The conservative assumption of no erosion for soil and sediment sources in the development of DCGLs , so there will be no source depletion from erosion .
The RESRAD model has limitations in this application in that it was developed for soil exposures and therefore does not specifically address certain transport mechanisms associated w.ith sediment, such as:
- Periodic saturation of the contaminated *zone located along a stream bank flood zone;
- Erosion/scour of stream bank material and subsequent downstream deposition to the stream-bottom ;
- Deposition of clean material onto the stream bank, transported downstream from unimpacted upstream locations;
- Variability in surface water concentrations due to fluctuation in flow rates during storm events;
- Partitioning of contaminants between the surface water and stream-bottom sediment; and
- Variabil ity of airborne dust loads due to varying stream bank sediment moisture content To address the simplifications of the conceptual model, and still retain conservatism in the results, the following assumptions were made for the sed iment model:
- The model will not allow the contaminated zone to be below the water table (as may periodically happen to the stream bank), therefore it was assumed that there was no unsaturated zone, and that the water table exists immediately below the source;
- The inhalation parameter values were conservatively selected to reflect soil on a farm, although stream bank sediment is likely to result in lower respirable dust loadings;
- Contaminated groundwater is assumed to discharge to the stream , where it is impounded and contributes to fish bioaccumulation;
- Fish ingested from the stream are large enough to provide a significant number of meals each year, but are assumed to only be exposed to contaminated water and never swim to uncontaminated sections of the stream ; and
- In addition to assuming the fish are never in clean water, the recreationist is assumed to eat only fish that are contaminated when , in actuality, the stream will not support fi sh at all at the present time owning to the small amount of water typically present as shown in Figure 5-11 .
The conceptual model just described represents plausible conditions on the stream banks and in the streambeds . It is considered to be a valid model for the long term in support of a Phase 2 strategy involving unrestricted release , that is, the site-wide removal alternative in the Decommissioning EI S. However, it would not necessarily serve as a valid Revision 2 5-39
WVDP PHASE 1 DECOMMISSIONING PLAN model if the Phase 2 sources were to be closed in place, as wi'th the site-wide olose-in-place alternative.
This lim'ita'tion results from the model not accounting for processes that could impact the streams in the future under the site-wide close-in-place alternative. For example, impacts on the streams could occur in the long term from unchecked erosion in the radioactive waste disposal areas, surface water runoff from eroded areas, and increased seepage of contaminated groundwater into the streams.. Such impacts could include increases in radionuclide concenlrations in water in the streams as well as increases in contamination in the sediment This limitation would be considered in any decision made by DOE to remediate sediment in the streams and on the stream banks. Such remediation during Phase 1 decommissioning activities wou.ld require a revision to this plan.
RESRAD input parameters were selected from the following sources, generally in the order given based on availability:
- Site-specific values where available, (e.g. groundwater and vadose zone parameters such as the distri bution coefficients li sted in Table 3-20 );
- Semi site-specific literature values , (e.g. physical values based on soil type from NUREG/CR-6697 (Yu , et al. 2000) and behavioral factors based on regional data in the U.S. Environmental Protection Agency'°s Exposure Factors Handbook (EPA 1997);
- Scenario-specific values using conservative industry defaults, (e.g., from the Exposure Factors Handbook, the RESRAD Data Collection Handbook (Yu , et al.
1993), NUREG/CR-6697 (Yu, et al. 2000), and NUREG/CR-5512, Volume 3 (Beyeler, et al. 1999);
- The most likely values among default RESRAD parameters defined by a distribution , when available , otherwise mean values from NUREG/CR-6697 (Yu , et al. 2000).
5.2.5 Summary of Results Table 5-8 provides the calculated individual radionucl ide DCGLs for surface soil ,
subsurface soil , and streambed sediment which assure that the dose to the average member of the critical group will not exceed 25 mrem per year when considering the dose contribution from each radionuclide individually. Note that the surface soil DCGLs apply only to areas of the project premises where there is no subsurface soil contamination and that the subsurface soil DCGLs apply only to the bottoms and lower sides (extending from a depth of three feet and greater) of the large excavations in WMA 1 and WMA 2.
Table 5-8. DCGLs For 25 mrem Per Year (DCGLw Values in pCi/g)(1J Nuclide Surface Soil Subsurface Soil(3 J Streambed Sediment Am-241 4.3E+01 7.1E+03 1.6E+04 C-14 2.0E+01 3.7E+05 3.4E+03 Revision 2 5-40
WVOP PHASE 1 DECOMMISSIONING PLAN Table 5-8. DCGLs For 25 mrem Per Year (DCGLw Values in pCi/g)(1J Nuclide Surface Soil Subsurface Soil(3l Streambed Sediment Cm-243 4.1E+01 1.2E+03 3.6E+03 Cm-244 8.2E+01 2.3E+04 4.8E+04 Cs-137(2 ) 2.4E+01 4.4E+02 1.3E+03 1-129 3.5E-01 5.2E+01 3.7E+03 Np-237 9.4E-02 4.3E+OO 5.2E+02 Pu-238 5.0E+01 1.5E+04 2.0E+04 Pu-239 4.5E+01 1.3E+04 1.8E+04 Pu-240 4.5E+01 1.3E+04 1.8E+04 Pu-241 1.4E+03 2.4E+05 5.1E+05 2
Sr-90< l 6.3E+OO 3.2E+03 9.5E+03 Tc-99 2.4E+01 1.1 E+04 2.2E+06 U-232 5.8E+OO 1.0E+02 2.6E+02 U-233 1.9E+01 1.9E+02 5.7E+04 U-234 2.0E+01 2.0E+02 6.0E+04 U-235 1.9E+01 2.1E+02 2.9E+03 U-238 2.1 E+01 2.1E+02 1.2E+04 NOTES: (1) Refer to Sections 5.2.7 and 5.2 .8 for discussions about how this set of DCGLs was considered in establishing cleanup goals.
(2) Sr-90 and Cs-137 DCGLs reflect 30 years of decay and apply to the year 2041 and later.
(3) The lower deterministic DCGL of the resident farmer and residential gardener conceptual models.
As noted previously, the sum-of-fractions rule will be applied if characterization data indicate that a mixture of radionuclides is present in an area.
Conclusions About Results Detailed outputs of the RESRAD simulations are presented in Appendix C. For surface soil, the results show that:
- Am-241 doses are due primarily to ingestion of plants,
- Cs-137 doses are due primarily to external exposure, and
- Sr-90 doses are due primarily to ingestion of plants.
The modeling to develop the subsurface soil DCGLs indicated that:
- Am-241 doses are due primarily to external exposure and ingestion of impacted plants,
- Cs-137 doses are due primarily to external exposure,
- Sr-90 doses are due primarily to ingestion of impacted plants and water, and
- DCGLs for subsurface soil are greater than those for the surface soil.
The modeling to develop the streambed sediment DCGLs indicated that:
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- Am-241 doses are due primarily to incidental ingestion of sediment and to external exposure,
- Cs-137 doses are due primarily to external exposure , as well as ingestion of I v enison ,
- Sr-90 doses are due primarily to ingestion of venison , and
- DCGLs for the sediment source are orders of magnitude greater than those for surface soil.
Conservatism in Calculations A number of factors make the DCGLs calculated using the initial base-case model conservative. For the surface soil DCGLs, these factors include , for example, the relatively sho.rt local growing season , which makes it likely that crop and forage yields will be less than those assumed for the site .
For the subsurface soil DCGLs , conservative factors include :
- As discussed previously, the diameter of the hypothetical well (cistern) used in the initial base ~case modeJ at two meters (about 6.6 feet) is much larger than the diameter of a typica l water well (eight inches) 13 .
- Use of the mass balance model within RESRAD is conservative in that all radionuclide inventory in leachate reaches the intake well.
- Because of the relatively short local growing season , it is likely that crop/forage yields will be less than those assumed for the site.
For the streambed sediment DCGLs, conservative factors include:
- Based on limited available data , the typical thickness of the contaminated zone is likely smaller than the one meter (about 3.3 feet) value used in the analysis.
- Based on available data , most contamination will be found in the stream beds , not on the banks.
- It is unlikely that the incidental ingestion rate (50 mg/d) for sediment will be exclusively from the contaminated area .
- It is assumed that all fish ingested by the recreationist are impacted by the streambed sediment source ; however, it is more likely that a recreationist may ingest fish from other locations as well.
- Similarly, it is unlikely that the venison ingested will be impacted by streambed sediment sources exclusively. It is more likely that exposure will be from both impacted and non-impacted areas.
13 With the larger diameter, much more contaminated soil and res idual radioactivity would be brought to the surface where it could cause exposure through various pathways . The difference in volume would vary w ith the square of the radius ; 100 times as much contaminated soil would be brought to the surface in the conceptual model with the two meter diameter well than with a model that assumed a 20 ce'ntimeter (eight inch) diameter well . The larger diameter well assumed ensures that the pumping needs of the residential farm would be met, since a smaller diameter well could not do this on some parts of the project premises .
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- Assumptions regarding the availability of an adequate fish population to allow long term fish ingestion may also result in overestimation of doses related to the sediment source, as there are currently no fish in the streams of sufficient quality or quantity for sustained human consumption.
Applicability of Streambed Sediment DCGLs The conceptual model used for developing DCGLs for stream bed sediment in Erdman Brook and the portion of Franks Creek on the project premises assumed that these streams have steep banks. This condition exists in most parts of the streams but not all parts .
Consequently, it is necessary to define where the stream bed sediment DCGLs and cleanup goals apply.
Figure 5-12 shows the points where the streambed sedimern t DCGLs and cleanup goals apply. As indicated on the figure, the surface soil DCGLs and cleanup goals apply upstream of these points and to the small tributaries to the streams.
Surface soil cleanup goals apply to gull ies and to tributaries to Erdman Brook and Franks Creek.
I Streambed sediment cleanup goals apply downstream of this point (surface soil cleanup goals apply upstream).
Figure 5-12. Areas Where Streambed Sediment DCGLs and Cleanup Goals Apply Revision 2 5-43
WVDP PHASE 1 DECOMMISSIONING PLAN 5.2.6 Discussion of Sensitiv ity Analyses Table 5-9 summarizes the sensitivity analyses performed for the surface soil DCGL base-case model , which are detailed in Appendix C.
Table 5-9 Summary of Parameter Sensitivity Analyses - Surface Soil DCGLs(1J Change in Minimum DCGL Change Maximum DCGL Change Parameter Run Sensitivity Parameter Change Nuclide(s) Change Nuclide(s)
Indoor/Outdoor 1 -32% -22% U-232 0% 1-129 Fraction 2 21 % 0% 1-129 U-234 28% U-232 Contamination 3 -50% 9% U-232 81% Sr-90 Zone Thickness 4 200% -28% U-235 0% Cs-137 Unsaturated 5 -50% -3% U-235 0% Cs-137 Sr-90 Zone Thickness U-232 6 150% 0% Cs-137 Sr-90 12% U-235 U-232 Irrigation/Pump 7 -57% -1% U-232 65% 1-129 Rate 8 70% -36% 1-129 1% U-232 Soil/Water 9 lower -71% U-234 0% Cs-1 37 Distribution Coefficients (Kd) 10 higher -3% U-232 867% U-234 Hydraulic 11 -55% -36% 1-129 0% Cs-137 Sr-90 Conductivity U-232 12 57% 0% Cs-137 Sr-90 40% 1-129 U-232 Runoff/ 13 -23% -29% U-234 2% U-232 Evaporation Coefficient 14 15% -2% U-232 79% 1-129 Depth of Well 15 -40% -40% 1-129 0.0% Cs-137 Sr-90 Intake U-232 16 100% 0% Cs-137 Sr-90 99% 1-129 U-232 Length Parallel 17 -30% 0% Cs-137 Sr-90 30% 1-129 to Aquifer Flow U-232 18 21 % -12% 1-129 0.0% Cs-137 Sr-90 U-232 Hydraulic 19 -33% -23% 1-129 0.0% Cs-137 Sr-90 Gradient U-232 20 33% 0% Cs-137 Sr-90 23.3% 1-129 U-232 Gamma 21 -38% 0% Cs-137 1-129 Sr-90 0.0% Cs-1371-1 29 Shielding Factor U-232 U-233 Sr-90 U-232 U-234 U-235 U-233 U-234 U-238 U-235 U-238 Revi sion 2 5-44
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Table 5-9 Summary of Parameter Sensitivity Analyses - Surface Soil DCGLs< >
Change in Minimum DCGL Change Maximum DCGL Change Parameter Run Sensitivity Parameter Change Nuclide(s) Change Nuclide(s) 22 87% -24% U-232 0.0% 1-129 Indoor Dust 23 -60% 0% Cs-137 1-129 0.2% U-232 Filtration Factor Sr-90 U-234 24 -25% 0% Cs-137 1-129 0.1% U-232 Sr-90 U-233 U-234 Dust Loading 25 -70% 0% Cs-137 1-129 0.3% U-232 Factor Sr-90 U-234 26 67% 0% U-232 0.0% Cs-137 1-129 Sr-90 U-235 U-238 Root Depth 27 -07% 0% Cs-f 37 I-129 0.0% Cs-137 1-129 Sr-90 U-232 Sr-90 U-232 U-233 U-234 U-233 U-234 U-235 U-238 U-235 U-238 28 233% 0% 1-129 193.7% Sr-90 Food Transfer 29 lower -38% U-235 875% Sr-90 Factors 30 higher -97% Sr-90 -42% U-238 Mass Balance 31 NA -67% U-234 0.0% Cs-137 Sr-90 Model U-232 NOTES: ( 1) Results presented here are for radionuclides considered likely to contribute significantly to the overall surface soil dose based on available characterization data .
Discussion of Surface Soil Results The sensitivity analysis results for the surface soil source model been evaluated considering those radionuclides that are the primary dose drivers, i.e., those that are likely to contribute significantly to predicted dose based on available characterization data. The radionuclides are Sr-90 (due to water independent plant uptake), 1-129 (due to water dependent pathways), Cs-137 (external radiation dose), and most uranium radionuclides (water dependent pathways).
The sensitivity analysis of the surface soil model , for these radionuclides , indicates the following :
- A lower indoor exposure fraction results in the larg~st DCGL decrease for U-232.
Similarly, a higher indoor exposure fraction results in the largest increase for U-232 and no change for 1-129 and U-234. However, it is unlikely that the indoor fraction is too low based ori the local climate. The U-232 doses are mainly due to external exposure , which accounts for the relative sensitivity to this parameter.
- Decreasing the source thickness increased the DCGL for all radionuclides and increasing the source thickness resulted in the most significant DCGL decrease for U-235. The sensitivity to this parameter is due to increased/decreased dose from the water ingestion and plant pathways (both water dependent and independent).
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- Decreasing the unsaturated zone thickness resulted in a decreased DCGL for U-235 and produced no change for Cs-137, 1-129, and U-232 . Similarly, increasing the unsaturated zone thickness increased the U-235 DCGL and produced no change for Cs-137, 1-129, and U-232. Sensitivity to this parameter is mainly due to increased/decreased travel time of contaminants to the saturated zone, resulting in water dependent doses occurring earlier/later with respect to doses from water independent pathways.
- Reducing the irrigation/well pump rate increased the DCGL fo r 1-129 most significantly. Similarly, increasing the pump rate decreased the DCGL for 1-129. Th is is because reducing the pumping rate results in a lower dilution factor, and increasing the pumping rate results in more radionuclide inventory available for exposure.
- The most significant effects of varying the Kd values were observed for U-234, which ranged from a decrease of 71 percent wheni lowering fhe Ka. to an inorease of 867 percent wheni inoreasing the Kd.
- Decreasing the hydraulic conductivity significantly reduced the DCGL for 1-129 due to reduced dilution and larger groundwater dose relative to other pathways at the time of peak dose . Similarly, increasing the hydraulic conductivity significantly increased the DCGL for 1-129.
- Variations in the runoff/evapotranspiration coefficients had the greatest effect on U-234 and 1-129, and the least impact on U-232. Radionuclides that are most sensitive to th is parameter have doses mainly due to water dependent pathways.
- Decreasing the well intake depth most significantly decreased the DCGL for 1-129, while increasing this parameter results in significantly increased the DCGL for 1-129, due to increased/decreased dilution in the well water.
- Changes to the parameter for length of contamination parallel to the aquifer flow had the most significant effect on the 1-129 DCGL, due to increased/decreased dilution in the aquifer.
- Changes to the hydraulic gradient most significantly impacted 1-129, due to the large water dependent pathway contributions.
- Decreasing the gamma shielding factor had no impact; however, increasing the shielding factor decreased the U-232 DCGL.
- Changes to the indoor dust filtration factor had minimal impact on DCGLs, due to relatively larger contribution to dose from other pathways.
- Similarly, changes to the dust loading factor had minimal impact on DCGLs, due to relatively larger contribution to dose from other pathways.
- Decreases in root depth did not significantly impact the DCGLs; however, increased root depth s impacted Sr"90 most significantly due to relatively large plant pathway doses.
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- Decreasing/increasing the plant transfer factors significantly increased/decreased the DCGL for Sr-90 , as dose is mainly due to ingestiorn via plant uptake from soil.
Table 5-1 O summarizes the sensitivity analyses performed for the subsurface soil initial base-case model DCGLs, which are detailed in Appendix C.
Table 5-10 Summary of Sensitivity Analyses - Subsurface Soil DCGLs Change in Minimum DCGL Change Maximum DCGL Change Parameter Run Sensitivity Parameter Change Nuclide(s) Change Nuclide(s)
Indoor/Outdoor 1 -32% -25% Cs-137 0.3% U-238 Fraction 2 21% 0% 1-1 29 35% U-232 Contamination 3 -67% -65% U-238 170% Sr-90 Zone Thickness 4 233% -4% U-232 98% U-234 Unsaturated Zone 5 -50% -1% 1-1 29 58% U-238 Thickness Cs-137 Sr-90 6 150% 0% 2218% U-234 U-232 U-235 Irrigation/Pump 7 -57% -39% 1-129 57% U-238 Rate 8 70% 0% Cs-137 20% 1-129 Soil/Water 9 lower -86% U-238 116% U-232 Distribution Coefficients (Kd) 10 higher -20% U-232 2168% U-234 Hydraulic 11 -55% 0% no change 0% no change Conductivity 12 57% 0% no change 0% no change Runoff/ 13 -23% -44% U-234 61% U-238 Evaporation Coefficient 14 15% -11% U-232 117% U-234 Indoor Gamma 15 -38% 0% U-238 19% U-232 Shielding Factor 16 87% -27% Cs-137 1% U-238 Indoor Dust 17 -60% 0% U-238 0% U-235 Filtration Factor Cs-1371-129 18 -25% 0% Sr-90 U-233 U- 0% U-235
'234 U-238 Inhalation Dust 19 -70% 0% U-238 1% U-233 Loading Cs-137 1-129 Sr-20 67% 0% U-235 0%
90 Root Depth 21 -67% -65% Sr-90 1% U-233 22 233% 0% U-238 181 % Sr-90 Food Transfer 23 lower -0.1% U-238 522% Sr-90 Factors 24 higher -93% Sr-90 0% U-234 Revision 2 5-47
WVDP PHASE 1 DECOMMISSIONING PLAN Discussion of Subsurface Soil Results The sensitivity analysis results for the subsurface soil source initial base-case model were evaluated considering those radionuclides that are the primary dose drivers, i.e.,
those that are likely to contribute significantly to predicted dose based on available characterization data (see Table 5-1). The radionuclides are Sr-90 (due to water independent plant uptake), 1-129 (due to water dependent pathways), Cs-137 (external radiation dose), and uranium radionuclides (water dependent pathways).
The sensitivity analysis of the subsurface soil model for these radionuclides indicates the following :
- A lower indoor exposure fraction results in a DCGL decrease for Cs-137 and no significant change for U-238. A higher indoor exposure results in a significant increased DCGL for U-232. However, it is unlikely that the indoor fraction is too low based on the local climate. Doses for these isotopes are mainly due to external exposure , which accounts for the relative sensitivity to this parameter.
- Decreasing or increasing the unsaturated zone thickness resulted in significant I changes for U-234 and U-238 .
- The most significant effects of varying the ~ values were observed for U-232, U-234, and U-238 .
- The hydraulic conductivity changes had no impact on DCGLs because the mass balance groundwater model was used .
- The U-232 and U-234 DCGLs are sensitive to changes in the runoff/
evapotranspiration coefficient. Radionuclides that are most sensitive to this parameter have doses mainly due to water dependent pathways.
- Changes to the gamma shielding factor most significantly impacted Cs-137 and U-232, based on a relatively large external exposure dose.
- The indoor dust filtration factor variations had no impact on DCGLs, due to relatively large dose contributions from other pathways.
- Changes to the dust loading factor had a minimal impact on DCGLs, due to relatively large dose contributions from other pathways.
- Varying the root zone depth impacted the Sr-90 DCGL most significantly.
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- The plant transfer factor is most sensitive for Sr-90 , as the dose is mainly due to ingestion via plant uptake.
Table 5-11 Summary of Sediment DCGL Sensitivity Analysis Change in Minimum DCGL Change Maximum DCGL Change Parameter Run Sensitivity Parameter Change Nuclide(s) Change Nuclide(s)
Outdoor Fraction 1 -50% 2% 1-129 97% U-232 2 100% -50% U-232 -3% 1-1 29 Source Thickness 3 -50% 0% U-235 29% Sr-90 4 200% -23% U-233 0% Cs-137 Soil/Water 5 lower -76.5% U-234 26% U-232 Distribution 6 higher -64.5% U-233 52% U-234 Coefficients (Kd)
Runoff/Evaporation 7 -23% 0% Cs-137 4% U-232 Coefficient 8 15% -3% i-129 0% Cs-137 Mass Loading for 9 -70% 0% Cs-137 1-129 1% U-233
.Inhalation Sr-90 U-232 10 67% -3% U-234 0% Cs-1371-129 Sr-90 Root Depth 11 -67% 0% no change 0% no change 12 233% 0% U-232 U-235 50% Sr-90 Food Transfer 13 lower 1% U-232 852% Sr-90 Factors 14 higher -98% Sr-90 -13% U-232 Discussion of Streambed Sediment Results The streambed sediment model sensitivity simulations have been evaluated considering those radionuclides that are likely to significantly contribute to the overall doses in this media , which are Sr-90 (venison ingestion) and Cs-137 (external radiation dose).
The sensitivity analysis for the sediment model , for these radionuclides , indicates:
While increasing the source thickness has little effect on these radionuclides , Sr-90 is most sensitive to this parameter.
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- Charnges to the mass loading factor hlad minimal impact on DCGLs.
- Decreasing the root zone depth did not impact DCGLs; however, increasing the depth increased the Sr-90 DCGL significantly.
Changes to Base-Case Models Based on Sensitivity Analysis Results Development of the conceptual model for surface soil DCGLs was an iterative process that used conservative assumptions for model parameters and took into account the results of early model runs and the related input parameter sensitivity analyses.
The initial model runs produced inordinately low DCGLs for uranium radionuclides in surface soil. The calculated DCGLw for U-238, for example, was 1.0 pCi/g , slightly above measured background concentrations in surface soil shown in Table 4-11 of this plan .
The next iteration involved changes to radionuclide distribution coefficients. Evaluation of the basis for the original distribution coefficients and sensitivity analysis results led to the conclusion that some distribution coefficients used were inappropriate . These distribution coefficients were changed . The resulting distribution coefficients are based either on site-specific data for the sand and gravel layer or, where site-specific data are not available, values for sand from Sheppard and Thibault 1990, as shown in Table C-2.
These model changes produced higher DCGLw values for uranium radionuclides , e.g .,
4.8 pCi/g for U-238. However, these values were still low compared to uranium DCGLs for unrestricted release developed at other sites. Further evaluation showed that the main reason for the low uranium DCGLs was the conservative use of the RESRAD mass balance model. After considering the results of the sensitivity analysis that evaluated use of the non-dispersion model , and RESRAD Manual guidance 14 , it was determined to be more appropriate to use the non-dispersion model in the surface soil analysis and this was done .
The probabilistic uncertainty analysis discussed in the next subsection provided insight into the degree of conservatism in model input parameters, producing DCGLs that were generally lower than those from the deterministic analyses.
5.2.7 Probabilistic Uncertainty Analysis The probabilistic uncertainty analysis has been performed for each of the three conceptual models to supplement the deterministic sensitivity analyses just described.
These probabilistic analyses generated results that quantify the total uncertainty in the 14 The RESRAD Manual (Yu , et al. 2001) notes in Appendi x E that:The user has the option of selecting which [groundwater] model to use. Usually, the MB [mass balance] model is used for smaller contaminated areas (e .g., 1,000 m2 or less) and the ND [non-dispersion] model is used for larger areas ."
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WVDP PHASE 1 DECOMMISSIONING PLAN DCGLs resulting from the variability of key input parameters, and also provide perspective regarding the relative importance of the contributions of different input parameters to the total uncertainty in the DCGLs. This information supports a risk-informed approach to establishing cleanup goals for Phase 1 of the decommissioning .
These analyses were performed using the probabilistic modules of RESRAD version 6.4, wh ich utilize Latin hypercube sampling, a modified Monte Carlo method , allowing for the generation of representative input parameter values from all segments of the input distributions. Input variables for the models were selected randomly from probability distribution functions for each parameter of interest The number of parameters treated probabilistically for each conceptual model was as follows: surface soil 102, subsurface soil 67, and streambed sediment 63, with these figures including the biotransfer factors and the Kct values for the 18 radionuclides of interest for each zone (contaminated , saturated, unsaturated) and media each model. Appendix E provides details of the analyses.
Table 5-11 a summarizes the results of the analyses .
Table 5-11a. Summary of Results of Probabilistic Uncertainty Analysesl' I Surface Soil DCGLs Subsurface Soil DCGLs Streambed Sediment DCGLs (pCi/g) (pCi/g) (pCi/g)
Nuclide Determ<2l Peak-of- Limitin~ Peak-of-Determ<5 > Peak-of-the-Mean<3>
the-Mean<3> Determ > the-Mean<3>
Am-241 4.3E+01 2.9E+01 7.1E+03 6.8E+03 1.6E+04 1.0E+04 C-14 2.0E+01 1.6E+01 3.7E+05 7.2E+05 3.4E+03 1.8E+03 Cm-243 4.1E+01 3.5E+01 1.2E+03 1.1E+03 3.6E+03 3.1E+03 Cm-244 8.2E+01 6.5E+01 2.3E+04 2.2E+04 4.8E+04 3.8E+03 6
Cs-137<l 2.4E+01 1.5E+01 4.4E+02 3.0E+02 1.3E+03 1.0E+03 1-129 3.5E-01 3.3E-01 5.2E+01 6.7E+02 3.7E+03 7.9E+02 Np-237 9.4E-02 2.6E-01 4.3E+OO 9.3E+01 5.2E+02 3.3E+02 Pu-238 5.0E+01 4.0E+01 1.5E+04 1.4E+04 2.0E+04 1.2E+04 Pu-239 4.5E+01 2.5E+01 1.3E+04 1.2E+04 1.8E+04 1.2E+04 Pu-240 4.5E+01 2.6E+01 1.3E+04 1.2E+04 1.8E+04 1.2E+04 Pu-241 1.4E+03 1.2E+03 2.4E+05 2.5E+05 5.1E+05 3.4E+05 Sr-90<5l 6.3E+OO 4.1E+OO 3.2E+03 3.4E+03 9.5E+03 4.7E+03 Tc-99 2.4E+01 2.1E+01 1.1E+04 1.4E+04 2.2E+06 6.6E+05 U-232 5.8E+OO 1.5E+OO 1.0E+02 7.4E+01 2.6E+02 2.2E+02 U-233 1.9E+01 8.3E+OO 1.9E+02 9.9E+03 5.7E+04 2.2E+04 U-234 2.0E+01 8.5E+OO 2.0E+02 1.3E+04 6.0E+04 2.2E+04 Revision 2 5-51
WVDP PHASE 1 DECOMMISSIONING PLAN Table 5-11a . Summary of Results of Probabilistic Uncertainty Analyses<~ !
Surface Soil DCGLs Subsurface Soil DCGLs Streambed Sediment DCGLs (pCi/g) (pCilg) (pCi/g)
Nuclide Determ<2 >
Peak-of- Limitin~ Peak-of-Determ<5 > Peak-of-the-Mean<3>
the-Mean<3> Determ l the-Mean<3l U-235 1.9E+0 1 3.SE+OO 2.1E+02 9.. 3E+02 2.9E+03 2.3E+03 U-238 2.1 E+0 1 9.8E+OO 2.1E+02 4. 6E+03 1.2E+04 8.2E+03 NOTES: ! 1) Values shown in boldface are lower of the pair of values being compared.
(2) Revised deterministic DCGLs based on parameter changes described in Appendix C.
(3) Probabilistic peak-of-the-mean DCGLs based on analyses described 1ir1 Appendix E.
(4) Tlhese values are thle limiting DCGLs for subsurface soil from the iresiderntial gardener alternate scenario analysis discussed above. Subsurface soil DCGLs are discussed further in Section 52..8, which describes the results of an analysis that takes into account continuing releases from the bottoms of the remediated deep excavations.
( 5) These are the revi sed DCGLs based on parameter changes described in Appendix C.
(6) These values take into account 30 years decay.
Table 5-11 a shows that:
- For surface soi.I, the peak-of-th e-m ean probabilistic DCGLs are lower than the revised determini stic DCGLs for all radionudides except Np-237.
- For subsurface soil, th e limiting deterministic analysis results from the residential gardener alternative scenario described above are more limiting than the peak-of-the-mean . DCGLs for 10 of the 18 radionuclides. (However, the additional determini stic multi-source analysis that includes continuing releases from the bottom s of the remediated deep excavation s as discu ssed in Section 5.2.8 results in even lower DCGLs for many of th e radionuclides of interest.)
- For streambed sediment, the peak-of-the-mean DCGLs are more limiting than the revised deterministic DCGLs.
For most radionucl ides, the 951h percentile probabili stic DCGLs are lower than th e peak-of-the-mean DCGLs as shown in Appendix E. The peak-of-the-m ean DCGLs are considered to be appropriate to compare with the deterministic DCGLs because NRC indicates that when using probabilistic dose modeling, the peak-of-the-mean dose distribution should be used for demonstrating com pliance with its License Term ination Rule in 10 CFR 20 , Subpart E (NRC 2006).
After consideration of the results of the probabilisti c uncertainty analysis and the analyses of alternate exposures discussed previously, DOE has determ ined that it is appropriate to use the peak-of-the-mean DCGLs for surface soil and for streambed sediment and the lowest DCGLs of the various subsurface soil evaluations. Subsurface soil DCGLs are addressed in Section 5.2.8.
5.2.8 Subsurface Soil DCGL Multi-Source Analysis As noted in Section 5.2.1, the original base-case conceptual model used in developing the subsurface soil DCGLs recognizes one source of contamination - the Lavery till from Revision 2 5-52
WVDP PHASE 1 DECOMMISSIONING PLAN the bottom of one of the deep excavations that is brought to the surface during construction of the hypothetical cistern . This model does not consider potential impacts to groundwater
- in the backfilled excavation from continuing release of remaining residual radioactivity at the bottom of the deep excavations.
To address this limitation , a111alyses were performed that take into account tihe impacts of releases of this other residual radioactivity on both a hypothetical residential gardener a 111d a resident farmer with a modrnied model that accounts for a surface and a subsurface source of radiation. Figure 5-13 illustrates the modified co111ceptual model used in these analyses.
Four surface contamination zone geometry/dilution factor (OF) combinations evaluated based on removal of a 3 m plug of unweathered Lavery till to the surface:
3 (1) 2000 m2 , 0.15 m thick , with a soil DF of 100 (2) 2000 m2 , 0.0015 m thick, with a soil DF of 1 r A residential gardener is the average member of the critical group for the 2
2000 m area scenarios. A resident farmer is the average member of the critical group for the 10,000 m scenario .
2 (3) 2000 m2 , 1 m thick, with a soil DF of 667 2
(4) 10,000 m , 1 m thick, with a soil DF of 3333 Backfill , unsaturated zone (2 m thick)
Contamination on bottom of excavation in area where cistern is installed is brought to surface and remaining subsurface source contributes to groundwater contamination Backfill, saturated zone Well (cistern) intake depth 5 m below water table Assu~ed 10,000 m2 , 1 m thick, Contamination located 10 m below surface diffuses into backfill \
early on \
Residual Radioactivity at Bottom of Excavation (Unweathered Lavery Till)
Hypothetical cistern t---:::============--t------! (2 m diameter well ,
10 m deep)
Diffusion/dispersion spreads contamination downward over time Shale Bedrock Figure 5-13. Modified Conceptual Model for Subsurface Soil DCGL Development With this model , the subsurface soil DCGLs are based on exposure to residual radioactivity associated with the bottom of the deep excavation in the unweathered Lavery till , with (1) soil from this area assumed to be relocated to the surface during installation of a cistern and (2) with the remaining contaminated Lavery till in the excavation bottom Revision 2 5-53
WVDP PHASE 1 DECOMMISS IONING PLAN serving as a continu ing source of contaminants to groundwater. These sources and the exposure pathways considered are described below.
Excavation Bottom Treated as Two Sources of Contamination The excavation bottom is treated as two distinct sources: (1 ) a plug of contaminated soil from the excavation bottom that is brought to the surface during installation of the cistern and spread over the entire sunface of the hypothetica l garden, and {2) the remaining contaminated Lavery till at the excavation bottom from wh ich residual rad ioactivity moves upward by diffusion arnd enters groundwater being drawn into the wel l. Both the residential gardener scena riio and the resident farmer scenario wene considered as indicated in Figure 5-13.
The surface source that results from the contribution of contamination in soil being removed from the bottom of the excavation and brought to the surface and the contri bution of co ntam ination in irrigation water has the following characteristics.:
- It is assumed that the contam inated material is evenly spread across the entire hypothetical garden and mixed uniform ly in the soil to varying depths (the surface contam ination zone),
- Exposure occurs from direct exposure and soil pathways associated with contam inated soil brought to the ground surface, and
- Exposure occurs from groundwater pathways as contam inated water is drawn into the well and used as irrigation water resulting in plant contamination and animal contamination where these plants are used as feed . As a result, the resident is exposed to radioactivity from the plants being consumed and, in the case of the resident farmer scenario, from meat and milk produced from cattle that have been raised on the contaminated feedstock.
The subsurface source remaining at the bottom of the excavation is assumed to have the following characteristics:
- The diffusive movement of contamination from the excavation bottom (the subsurface contam ination zone) begins immediately after the excavation is backfilled and results in contaminating the aquifer,
- Contaminated groundwater entering the well is a source to soil in the surface contamination zone because well water is used to irrigate the garden, and
- Drinking water exposure occurs from contaminated well water being used as a source of drinking water.
Table 5-11 b shows the exposure pathways evaluated.
Table 5-11b. Exposure Pathways for Modified Subsurface Soil DCGL Model Residential Resident Exposure Pathways Gardener Farmer External gamma radiation from contaminated soil Yes Yes Inhalation of airborne radioactivity from re-suspended Yes Yes Revision 2 5-54
WVDP PHASE 1 DECOMM ISSIONING P LAN Table 5-11 b. Exposure Pathways for Modified Subsurface Soil DCGL Model Residential Resident Exposure Pathways Gardener Farmer contaminated soil Plant ingestion (produce impacted by contaminated soil Yes Yes and groundwater contam inated by primary and secondary sources)
Meat ingestion (beef impacted by contam inated soil and No Yes groundwater contaminated by primary and secondary sources)
Milk ingestion (impacted by contaminated soil and No Yes groundwater contam inated by primary and secondary sources)
Aquatic food ingestion No No Ingestion of drinking water (from groundwater Yes Yes contaminated by primary and secondary sources)
Soil ingestion Yes Yes Radon inhalation No No Details of the modeling including values of input parameters such as distribution coefficients appear in the calculation package (Price 2009).
Mathematical Models Calculation of the combined dose utilized information from the three-dimensional near field STOMP finite difference model of the north plateau for groundwater transport, a model that estimated the drinking water dose associated with contamination from the subsurface source diffusing into the aquifer, and RESRAD dose to source ratios associated with unit soil concentrations to determine the total dose from all pathways. The calculations were implemented with a FORTRAN language computer program that estimates time dependent 15 human health impacts.
The model performs mass balance calculations and develops concentrations over time for three distinct areas (1) the remaining subsurface source, (2) the backfilled saturated zone, and (3) the surface which has been contaminated with material excavated from the subsurface source and radionuclides in irrigation water.
In order to identify controlling scenarios, the area of the contaminated zone at the surface and the degree of mixing into the soil of the garden were varied.
The STOMP model was executed with parameter values for the contaminated area and well pumping rates that corresponded with assumptions used in the RESRAD model for the 2
exposure scenarios under consideration. A contaminated area of 10,000 m and pumping rate of 5720 m3/y were used to evaluate the resident farmer, and a contaminated area of 2,000 m2 and well pumping rate of 1140 m3/y were used to evaluate the residential gardener scenario. The residential gardener scenario assumed several source 15 These analyses were deterministic analyses. Consideration was given to performing probabilistic analyses instead. However, the complexity of the multi-source model made a probabilistic analysis impractical.
Revision 2 5-55
WVDP PHASE 1 DECOMMISSIONING PLAN configurations within the contamirna'ted area for the three m'l of contaminated Lavery til l assumed to be excavated to the surface:
- Contam ination is spread over the surface in a thin !layer (11 .5 mm thick) of undiluted till ,
- Contam ination is spread over the surface and then Nlled into the soil to a depth of 15 cm, and
- Contamirnation is spread over the surface and then tilled into the soil to a depth of 1 m.
The source configuration determined t o be most limiting for each radionuclide was used as the basis for the development of the subsurface DCGLs.
Results Table 5-11 c shows the results of the analyses compared to DGCLs developed using other conceptual models.
1 Table 5-11c. Subsurface Soil DCGL Comparison (pCiJgt '
Basic Probabilistic Cistern Well Recreat. Lagoon 3 Natural Gas Nuclide Multi-Source Deterministic Peak of the*
Driller Hiker Erosion Well Driller Models(2l Mean Am-241 6.3E+03 1.7E+04 2.7E+05 2.9E+05 1.4E+05 7.1E+03 6.8E+03 C-14 9.9E+02 2.3E+09 3.3E+08 6.4E+06 4.9E+09 3.7E+05 7.2E+05 Cm-243 3.6E+03 1.1E+04 5.0E+04 1.8E+05 1.2E+05 1.2E+03 1.1E+03 Cm-244 3.4E+04 3.3E+04 1.0E+09 3.9E+05 2.6E+05 2.3E+04 2.2E+04 Cs-137(3) 2.8E+03 6.7E+03 9.8E+05 7.4E+05 9.2E+04 4.4E+02 3.0E+02 1-129 7.SE+OO 8.0E+05 1.9E+06 3.5E+05 9.2E+06 5.2E+01 6.7E+02 Np-237 1.0E+OO 6.6E+03 2.7E+04 5.9E+05 6.6E+04 4.3E+OO 9.3E+01 Pu-238 1.3E+04 2.0E+04 1.5E+06 2.7E+05 1.6E+05 1.5E+04 1.4E+04 Pu-239 3.1 E+03 1.9E+04 2.8E+05 2.4E+05 1.5E+05 1.3E+04 1.2E+04 Pu-240 3.4E+03 1.9E+04 2.8E+05 2.4E+05 1.5E+05 1.3E+04 1.2E+04 Pu-241 5.5E+05 5.5E+05 1.7E+07 1.2E+07 4.5E+06 2.4E+05 2.5E+05
. Sr-90f3l 2.8E+02 8.7E+05 1.6E+08 9.2E+06 1.1E+07 3.2E+03 3.4E+03 Tc-99 5.9E+02 7.9E+07 2.2E+08 4.7E+07 9.4E+08 1.1E+04 1.4E+04 U-232 8.8E+01 1.6E+03 2.8E+04 4.5E+05 1.6E+04 1.0E+02 7.4E+01 U-233 2.7E+02 6.2E+04 1.3E+06 2.9E+06 4.9E+05 1.9E+02 9.9E+03 U-234 2.8E+02 6.4E+04 1.4E+06 3.1E+06 5.0E+05 2.0E+02 1.3E+04 U-235 2.9E+02 1.2E+04 4.2E+04 3.2E+06 1.4E+05 2.1 E+02 9.3E+02 U-238 3.0E+02 3.7E+04 1.9E+05 3.3E+06 3.6E+05 2.1E+02 4.6E+03 NOTES: (1) The lowest DCGLs are shown in boldface.
(2) The lower value of the deterministic resident farmer and residential gardener DCGLs.
(3) These values take into account 30 years decay.
Revision 2 5-56
WVDP PHASE 1 DECOMMISSIONING PLAN In nine cases , the DCGLs developed using other conceptual models are lower than the DCGLs developed by the multi-source model that accounts for continuing releases from the bottom of the deep excavations:
- The peak-of-the-mean probabilistic DCGLs, which did not take 'into account continuing releases from the bottom of the deep excavations, are lower for Cm -
243, Cm-244, Cs-137, and U-232; and
This situation can be attributed to conceptual model differences such as different contamination zone geometry.
5.2.9 Overall Conclusions Development of DCGLs proved to be an iterative process.
For surface soil DCGLs, the initial-base case conceptual model was determined to be more conservati ve than an alternate conceptual model involving erosion and the resulting potential doses to an offsite receptor. However, the probabilistic peak-of-the-mean DCGLs were lower than the base-case deterministic DCGLs fo r all radionuclides except Np-237.
The peak-of-the-mean DCGLs were therefore selected as the basis for the surface soil oleanup goals to be conservative .
For subsurface soil DCGLs, analysis of the residential gardener and the multisource alternate conceptual models showed that the initial base-case resident farmer model was not conservative . The probabilistic uncertainty analysis provided additional insight into potential futu re doses from residual rad ioactivity at the bottom of the deep excavations. In the interest of conservatism, the lowest DCGLs produced by the va rious models were selected as the basis for the subsurface soil cleanup goals.
For streambed sediment DCGLs, the refined base-case model produced essentially the same DCGLs as the initial base-case model. However, the probabilistic peak-of-the-mean DCGLs were lower and were therefore selected as the basis for the cleanup goals.
5.3 Limited Site-Wide Dose Assessment This section describes the limited integrated dose assessment performed to ensure that criteria used in Phase 1 remediation activities will not limit options for Phase 2 of the decommissioning .
5.3.1 Basis for this Assessment Section 5.1 .3 explains why such a dose assessment is appropriate, considering the Phase 1 and Phase 2 sources illustrated in Figure 5-4. Section 5.1 .3 also explains that the appropriate dose assessment involves a hypothetical individual engaged in farming at some time in the future on one part of the remediated project premises who also spends time fishing and hiking at Erdman Brook and Franks Creek.
Revision 2 5-57
WVDP PHASE 1 DECOMMISSIONING PLAN This scenario would involve an individual being exposed to two different remediated source areas and being a member of the two different critical groups. As described in Section 5.2, the exposure group for the resident farmer scenario used for development of DCGLs for surface and subsurface soil is significantly different from the exposure group for the development of the streambed sediment DCGLs, which involves a hypothetical individual spending a relatively small fraction of his or her time hiking , fishing, and hunting in the areas of Erdman Brook and Franks Creek.
In both of these cases , it was assumed that the hypothetical individual (the average member of the critical group) would be exposed only to the residual radioactivity of interest.
That is, the resident farmer would not be exposed to residual radioactivity in the areas of the streams and the recreationist would not be exposed to residual radioactivity in surface soil or subsurface soil.
5.3.2 Assessment Approach The approach used involves partitioning doses between two critical groups and two areas of interest: (1) the resident farmer who lives in an area of the project premises where surface soil or subsurface soil has been remediated to the respective DCGLs and (2) the person who spends time in the areas of the streams hiking, fishing , and hunting (the recreationist). This approach is analogous to addressing multiple radionuclides in contaminated media of interest using the sum -of-fractions approach or unity rule (NRC 2006).
Consideration of potential risks related to the different areas led assigning 90 percent 0f the total dose limit of 25 mrem per year to the resident farmer activities and 10 percent to the recreational activities. This arrangement involves assigning an acceptable dose of 22.5 mrem per year to resident farmer activities and 2.5 mrem per year to recreation in the area of the streams, values which total 25 mrem per year.16 The assessment was then performed using the base case analysis results for the resident farmer and the recreationist at Erdman Brook and Franks Creek.
Two separate assessments were performed with the resident farmer located in : (1) the area of the remediated WMA 1 subsurface soil excavation , and (2) the resident farmer located in an area where surface soil was assumed to have been remediated . Details appear in Appendix C.
5.3.3 Results of the Assessments Table 5-12 provides the assessment results for the WMA 1 subsurface soil case and Table 5-13 provides the results for the surface soil case. The streambed sediment DCGLw values are the same in both cases because the apportioned dose limit of 2.5 mrem per year is the same.
16 This 0.90/0.10 split is based on judgment related to relative risk. Consideration was given to using a split based on the relative time the hypothetical farmer would spend in the area of the farm compared to the area of the streams . However, because the assumed time in the area of the streams is relatively small at 104 hours0.0012 days <br />0.0289 hours <br />1.719577e-4 weeks <br />3.9572e-5 months <br /> per year, such as spilt could result in an allowable annual dose of 24.7 mrem for resident farmer activities and 0.3 mrem for recreation at the streams . This split would have a minimal impact on the soil DCGLs while driving the streambed sediment DCGLs to unrealistically low levels.
Revision 2 5-58
WVDP PHASE 1 DECOMMISSIONING PLAN Table 5-12. Limited Site-Wide Dose Assessment 1 Results (DCGLs in pCi/g)
Subsurface Soil DCGLw Values Streambed Sediment DCGLw Values Nuclide Base Case< l 1 Assessment(2l Base Case(1l Assessment(2l Am-241 6.3E+03 5.7E+03 1.0E+04 1.0E+03 C-14 9.9E+02 8.9E+02 1.8E+03 1.8E+02 Cm-243 1.1E+03 9.9E+02 3.1E+03 3.1E+02 Cm-244 2.2E+04 2.0E+04 3.8E+04 3.8E+03 3
Cs-137( l 3.0E+02 2.7E+02 1.0E+03 1.0E+02 1-129 7.5E+OO 6.8E+OO 7.9E+02 7.9E+01 Np-237 1.0E+OO 9.0E-01 3.2E+02 3.2E+01 Pu-238 1.3E+04 1.2E+04 1.2E+04 1.2E+03 Pu-239 3.1E+03 2.8E+03 1.2E+04 1.2E+03 Pu-240 3.4E+03 3.1E+03 1.2E+04 1.2E+03 Pu-241 2.4E+05 2.2E+05 3.4E+05 3.4E+04 3
Sr-90( l 2.8E+02 2.5E+02 4.7E+03 4.7E+02 Tc-99 5.9E+02 5.3E+02 6.6E+05 6.6E+04 U-232 7.4E+01 6.7E+01 2.2E+02 2.2E+01 U-233 1.9E+02 1.7E+02 2.2E+04 2.2E+03 U-234 2.0E+02 1.8E+02 2.2E+04 2.2E+03 U-235 2.1E+02 1.9E+02 2.3E+03 2.3E+02 U-238 2.1E+02 1.9E+02 8.2E+03 8.2E+02 NOTES: (1) The base-case values for subsurface soil are the lowest values from Table 5-11c and the base-case values for streambed sediment are the lowest values from Table 5-11a.
(2) The results for the analysis of the combined base-case in this table (the lowest DCGLs in the various analyses for subsurface soil) and the recreationist in the area of the strearns.
(3) These DCGLs apply in the year 2041 and later.
As can be seen from Table 5-13, the dose partitioning approach reduced the DCGLw values for surface soil by 10 percent and reduced the DCGLw values for streambed sediment by an order of magnitude.
Table 5-13. Limited Site-Wide Dose Assessment 2 Results (DCGLs in pCi/g)
Surface Soil DCGLw Values Streambed Sediment DCGLw Values Nuclide 1 Base Case( l Assessment( l 2 Base Case(1l Assessment(2 )
Am-241 2.9E+01 2.6E+01 1.0E+04 1.0E+03 C-14 1.6E+01 1.5E+01 1.8E+03 1.8E+02 Cm-243 3.5E+01 3.1E+01 3.1 E+03 3.1E+02 Cm-244 6.5E+01 5.8E+01 3.8E+04 3.8E+03 Cs-137(3l 1.5E+01 1.4E+01 1.0E+03 1.0E+02 1-129 3.3E-01 2.9E-01 7.9E+02 7.9E+01 Np-237 2.6E-01 2.3E-01 3.2E+02 3.2E+01 Pu-238 4.0E+01 3.6E+01 1.2E+04 1.2E+03 Revision 2 5-59
WVDP PHASE 1 DECOMMISSIONING PLAN Table 5-13. Limited Site-Wide Dose Assessment 2 Results (DCGLs in pCi/g)
Surface Soil DCGLw Values Streambed Sediment DCGLw Values Nuclide Base Case<1l Assessment<2l Base Case<1l Assessment<2l Pu-239 2.5E+01 2.3E+01 1.2E+04 1.2E+03 Pu-240 2.6E+01 2.4E+01 1.2E+04 1.2E+03 Pu-241 1.2E+03 1.0E+03 3.4E+05 3.4E+04 3
Sr-90< l 4.1E+OO 3.7E+OO 4.7E+03 4.7E+02 Tc-99 2. 1E+0 1 1.9E+01 6.6E+05 6.6E+04 U-232 1.5E+OO 1.4E+OO 2.2E+02 2.2E+01 U-233 8.3E+OO 7.5E+OO 2 .2E+04 2.2E+03 U-234 8.4E+OO 7.6E+OO 2.2E+04 2.2E+03 U-235 3.5E+OO 3.1E+OO 2.3E+03 2.3E+02 U-238 9.8E+OO 8.9E+OO 8.2E+03 8.2E+02 NOTES: (1) The base-case va lues are the lowest values from Table 5-11a.
(2) The results for the analysi s of the combined base case in this table (the lowest DCGLs in the various analyses for subsurface soil} and the recreationist in the area of the streams.
(3) These DCGLs apply in the year 2041 and later.
5.4 Cleanup Goals and Additional Analyses This section (1) identifies the cleanup goals to be used in remed iation of surface soil, subsurface soil , and streambed sediment and the basis for these cleanup goals; (2) describes how the DCGLs and the cleanup goals will be later refined ; (3) discusses use of surrogate radionuclides ; and (4) identifies plans for the dose assessment of the remediated WMA 1 and WMA 2 areas.
5.4.1 Cleanup Goals As explained in Section 5.1.6, the dose modeling process includes establishing cleanup goals below the DCGLs developed to meet the 25 mrem per year unrestricted dose limit that are to be used to guide remediation efforts, considering the results of the analysis of the combined source area exposure scenario described in Section 5.3 and the ALARA analysis described in Section 6.
Combined Source Area Analysis As indicated in Section 5.3, analysis of the limiting scenario for dose integration - a resident farmer living on the remed iated project premises who spends time in the vicinity of Erdman Brook and Franks Creek hiking , fishing , and hunting - produced lower DCGLw values for both critical groups, with the reduction for the recreationist in the area of the streams being a much greater percentage.
ALARA Analysis Section 6 describes the process used to evaluate whether remed iation of surface soil ,
subsurface soil , and streambed sediment below DCGLs based on 25 mrem/y would be cost-effective , following the standard NRC methodology for ALARA analyses. Section 6 Revision 2 5-60
WVDP PHASE 1 DECOMMISSIONING PLAN provides the results of a preliminary analysis and provides for a final ALARA analysis to be performed during the Phase 1 decommissioning work.
The preliminary ALARA analysis suggests that the costs of removing slightly contaminated soil or sediment at concentrations below the DCGLs for 25 mrem per year will outweigh the benefits. That is, areas where surface soil , subsurface soil , and stream sediment are remediated to radioactivity concentrations at the DCGLs satisfy the ALARA criteria. The evaluation process balances the cost of offsite disposal of additional radioactively contaminated soil (cost of $6.76 per cubic foot) and the benefits of reduced dose (benefit of $2000 per person-rem as set forth in NRC guidance).
The final ALARA analysis that will be performed during the Phase 1 decommissioning activities will make use of updated information , such as actual rather than predicted waste disposal costs. However, the results will likely be similar to the preliminary analysis .
Section 6 explains that the methods to be used in remediation of contaminated soil and sediment, which involve excavation of the material in bulk quantities , will generally remove more material than necessary to meet the DCGLs. As noted in Section 6, NRC recognizes that soil excavation is a coarse removal process that is likely to remove large fractions of the remaining radioactivity (NRC 1997). The contaminated soil and sediment removal method is therefore expected to produce residual radioactivity concentrations well below the DCGLs.
Cleanup Goals Demonstration that the decommissioning activities have achieved the desired dose-based criteria is through the process described in the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) (NRC 2000). This process is outlined in Section 9, wh ich describes the general content of the Phase 1 Final Status Survey Plan . The Phase 1 Final Status Survey Plan provides the details.
For surface soils and sediments in the WVDP Phase 1 areas, the field cleanup goal need not be too far below the DCGL, if at all. As discussed previously, bulk excavation will generally remove more material than necessary to meet the DCGL, so it is likely that the post-remediation average concentration will be below whatever in-process goal is chosen.
And the costs for additional remediation of a surface soil or sediment site , while extra , are not unusually high .
However, for subsurface soils a field cleanup goal should be well below the DCGL because of the large costs to be incurred if additional remediation were necessary to an area that failed the statistical testing. Re-excavating to depth with shoring , engineering controls, and management or disposal of extensive overburden would be expensive compared to excavating some additional material in the original remediation.
Consideration of such factors led to DOE establishing in this plan the cleanup goals shown in Table 5-14. Note that the surface soil cleanup goals apply only to areas of the project premises where there is no subsurface soil contamination and that the subsurface soil cleanup goals apply only to the bottoms and lower sides (extending from a depth of three feet and greater) of the large excavations in WMA 1 and WMA 2.
Revision 2 5-61
WVDP PHASE 1 DECOMMISSIONING PLAN 1
Table 5-14. Cleanup Goals to be Used in Remediation in pCi/9 ( >
Surface Soi1(2 > Subsurface Soi1(3l Streambed Sediment(2l Nuclide CGw CGEMC CGw CG EMC CGw CG EMC Am-241 2.6E+01 3.9E+03 2.8E+03 1.2E+04 1.0E+03 2 .1E+04 C-14 1.5E+01 1.6E+06 4.5E+02 8.0E+04 1.8E+02 5.9E+05 Cm-243 3.1E+01 7.5E+02 5.0E+02 4.0E+03 3.1E+02 2.8E+03 Cm-244 5.8E+01 1.2E+04 9.9E+03 4.5E+04 3.8E+03 3.6E+05 Cs-137(4 > 1.4E+01 3.0E+02 1.4E+02 1.7E+03 1.0E+02 9.4E+02 1-129 2.9E-01 6.0E+02 3.4E+OO 3.4E+02 7.9E+01 2.0E+04 Np-237 2.3E-01 7.5E+01 4.5E- 01 4.3E+01 3.2E+01 UE+03 Pu-238 3.6E+01 7.6E+03 5.9E+03 2.8E+04 1.2E+03 1.7E+05 Pu-239 2.3E+01 6.9E+03 1.4E+03 2.6E+04 1.2E+03 1.7E+05 Pu-240 2.4E+01 6.9E+03 1.5E+03 2.6E+04 1.2E+03 1.7E+05 Pu-241 1.0E+03 1.3E+05 1.1E+05 6.8E+05 3.4E+04 7.5E+05 Sr-90(4 ) 3.7E+OO 7.9E+03 1.3E+02 7.3E+03 4.7E+02 7.1E+04 Tc-99 1.9E+01 2.6E+04 2.7E+02 1.5E+04 6.6E+04 4.2E+06 U-232 1.4E+OO 5.9E+01 3.3E+01 4.2E+02 2.2E+01 2.1 E+02 U-233 7.5E+OO 8.0E+03 8.6E+01 9.4E+03 2.2E+03 4.4E+04 U-234 7.6E+OO 1.6E+04 9.0E+01 9.4E+03 2.2E+03 2 .1E+05 U-235 3.1E+OO 6.1 E+02 9.5E+01 3.3E+03 2.3E+02 2.0E+03 U-238 8.9E+OO 2.9E+03 9.5E+01 9.9E+03 8.2E+02 8.2E+03 NOTE: (1) These cleanup goals (CGs) are to be used as the criteria for the remediation activities described in Section 7 of this plan. Note that the streambed sediment cleanup goals will support unrestricted release of the project premises but will not necessarily support restricted release alternatives due to the continued presence of Phase 2 sources as discussed in Section 5.2.2.
(2) The CGw values for surface soil and streambed sediment are the same as the limited dose assessment DCGL values in the third and fifth columns of Table 5-1 3, respectively . The CGEMc values are based on the limiting case among the probabilistic analysis resident farmer analysis, the deterministic resident farmer analysis, and the deterministic residential gardener analysis.
(3) These CGw values are the assessment values in the third column of Table 5-12 reduced by a factor of 0.50 as discussed below. The DCGLsMc values are the limiting values from the multi-source analysis or the deterministic resident farmer/residential gardener deterministic analyses using the 1 2
m area factor from Table 9-2. The subsurface soil cleanup goals apply only to the bottoms of the WMA 1 and WMA 2 deep excavations and to the sides of these excavations more than three feet below the ground surface.
(4) The cleanup goals for Sr-90 and Cs-137 apply to the year 2041 and later, that is, they incorporate a 30-year decay period from 2011 . The 30-year decay period was selected for these key radionuclides because of their short half-life. As noted previously, the Phase 2 decision could be made within 10 years of issue of the Record of Decision and Findings Statement documenting the Phase 1 decision.
If this approach were to involve unrestricted release of the site, achieving this condition would be expected to take more than 20 years due to the large scope of effort to exhume the underground waste tanks and the NOA. It is therefore highly unlikely that conditions for unrestricted release of the project premises could be established before 2041 . If Phase 2 were to involve closing radioactive facilities in place, then institutional controls would remain in place after 2041 . DOE will be responsible for maintaining institutional control of the project premises and providing for monitoring and maintenance of the project premises until completion of Phase 2 of the decommissioning .
The basis for these cleanup goals is as follows. Compliance with the cleanup goals used for remediation when mixtures of radionuclides are present will be determined by use of the sum-of-fractions approach .
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WVDP PHASE 1 DECOMMISSIONING PLAN Basis for Cleanup Goals for Surface Soil The surface soil CGw values are the values in the Surface Soil DCGLw Assessment column of Table 5-13. DOE considers these goals to be conservative and appropriate to provide assurance that any remediation of surface soil and sediment in drainage ditches on the project premises that may be accomplished during Phase 1 of the decommissioning will support releasing the remediated areas under the criteria of 10 CFR 20 .1402, should the licensee eventually determine that approach to be appropriate for Phase 2 of the 17 decommissioning .
Basis for Cleanup Goals for Subsurface Soil DOE has established the subsurface soil cleanup goals at 50 percent of subsurface soil DCGLs calculated in the limited site-wide dose assessments for 22.5 mrem per year (Table 5-12). The cleanup goals for subsurface soil will therefore equate to 11 .25 mrem per year.
DOE is takin~ this approach to provide additional assurance that remediation of the WMA 1 and WMA 2 excavated areas will support all potential options for Phase 2 of the decommissioning . As indicated previously, these cleanup goals apply only to the bottom of fhe large WMA 1 and WMA 2 excavations and to the sides of these excavations three feet or more below the surface.
Basis for Cleanup Goals for Streambed Sediment DOE has used the DCGLw values from the limited site-wide dose assessment (the last column in Table 5-12 and Table 5-13) as the cleanup goals for streambed sediment. These values are substantially less than those developed for the base-case recreationist scenario and are considered to be supportive of any approach that may be selected for Phase 2 of the decommissioning .
As noted in the discussion on the ALAR.A analysis results , DOE expects that the actual levels of residual radioactivity will turn out to be less than the DCGLs used for remediation ,
i.e ., these cleanup goals, owing to the characteristics of the remediation method to be used .
5.4.2 Refining DCGLs and Cleanup Goals The calcu lated DCGLs for 25 mrem per year and the associated cleanup goals will be refined as appropriate after the data from the soil and sediment characterization program to be completed early in Phase 1 of the decommissioning becomes available . These data are expected to provide additional insight into the radionuclides of interest in environmental media and the depth and areal distribution of the contamination. Such information could , for example, lead to deleting one or more radionuclides from further consid~ration in the Phase 1 cleanup or lead to more realistic source geometry for development of DCGLs for surface soil contamination . Analytical data from the subsurface soil characterization measurements being taken in 2008 could also provide information to help refine the subsurface soil DCGLs .
17 As noted previously, surface soil may or may not be remediated in Phase 1 of the decomm ission ing.
However, it is possible that characterization performed early in Phase 1 could identify surface soil contamination that would warrant remediation to reduce radiation doses during the period between Phase 1 and Phase 2 of the decommission ing. In the un likely event that this situation developed , the areas of concern would be remed iated in Phase 1.
Revision 2 5-63
WVDP PHASE 1 DECOMMISSIONING PLAN If evaluation of the new data leads to refinement of the DCGLs and cleanup goals, then this plan will be revised accordingly to reflect the new values . Since such a change could affect the project end conditions , the plan revision would be provided to NRC for review and input prior to issue following the change process described in Section 1.
5.4.3 Use of a Surrogate Radionuclide DCGL A surrogate radionuclide is a radionuclide in a mixture of rad ionuclides whose concentration is easily measured and can be used to infer the concentrations of the other radionuclides in the mixture. If actual radioactive contamination levels of the surrogate radionuclide are below the specified concentration , then the sum of doses from all 18 radionuclides in the mixture will fall below the dose limit.
The tables in this section do not provide DCGLw values for a surrogate radionuclide because available data on radionuclide distributions in soil and sediment are not sufficient to support this . However, surrogate radionuclide DCGLw values for the cleanup goals will be developed and incorporated into this section if evaluation of additional characterization data shows that Cs-137 or another easy to measure radionuclide can be used effectively as a surrogate for all radionuclides in source soil , subsurface soil , and/or streambed sediment in an area .
5.4.4 Preliminary Dose Assessment Preliminary dose assessments have been performed for the remediated WMA 1 and WMA 2 excavations. These assessments made use of the maximum measured radioactivity concentration in the Lavery till for each radionuclide as summarized in Table 5-1, and the results of modeling to develop DCGLs for 25 mrem per year and the multi-source analysis results as shown in Table 5-11c . The results were as follow:
WMA 1, a maximum of approximately 8 mrem a year WMA 2, a maximum of approximately 0.2 mrem a year Given the limited data available , these results must be viewed as order-of-magnitude estimates. However, they do suggest that actual potential doses from the two remediated areas are likely to be substantially below 25 mrem per year. Note that the primary dose driver for these estimates is Sr-90 , which accounts for approximately 66 percent of the estimated dose for the WMA 1 excavation and approximately 61 percent of the estimate for the WMA 2 excavation .
NOTE The use of maximum rather than average values in these dose estimates adds conservatism , as does including values that are simply the highest minimum detectable concentrations , especially in the case of Np-237. (There was a wide range of several orders of magnitude among the minimum detectable concentrations reported for the 2008 sample data.) As with the DCGLs, decay of Sr-90 and Cs-137 over 30 years is accounted for in the estimate.
18 Guidance on the use of surrogate measurements provided in Section 4.3.2 of NUREG-1575 , Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) (NRC 2000) would be followed.
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WVDP PHASE 1 DECOMMISSIONING PLAN As noted previously, DOE will perform a dose assessment for the residual radioactivity in the WMA 1 and WMA 2 excavated areas using Phase 1 final status survey data . This assessment will use the same methodology used in development of the subsurface soil DCGLs to estimate the potential radiation dose using the actual measured residual radioactivity concentrations. The results of the dose assessment will be* made available to NRC and other stakeholders. Note that a more-comprehensive dose assessment that also takes into account the Phase 2 sources may be performed in connection with Phase 2 of the decommissioning , depending on the approach selected for that phase .
5.5 Monitoring, Maintenance, and Institutional Controls Inherent in the use of the 30-year decay period used in development of DCGLs and cleanup goals for Sr-90 and Cs-137 is the assumption that all or part of the project premises will not be released for unrestricted use before 2041. DOE will be responsible for 1
monitoring and maintenance of the project premises and for maintaining institutional controls until completion of Phase 2 of the WVDP decommissioning , which is assumed to occur after 2041 if Phase 2 were to be designed to meet unrestricted release criteria. If a olose-in-place approach was selected for Phase 2, then institutional controls are assumed to be required beyond 2041 .
5.6 References Code of Federal Regulations 10 CFR 20 , Subpart E, Radiological Criteria For License Termination (L TR).
10 CFR 20.1003 , Definitions.
DOE Orders DOE Order 450.1, Environmental Protection Program, including Changes 1 and 2. U.S, Departmen~ of Energy, Washington , D.C. January 15, 2003.
DOE Order 5400 .5, Radiation Protection of the Public and the Environment, Change 2.
U.S, Department of Energy, Washington , D.C., January 7, 1993.
DOE Technical Standards DOE Standard 1153-2002, A Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota. U.S, Department of Energy, Washington, D.C., July 2002.
Other References Beyeler, et al. 1~99 , Residual Radioactivity from Decommissioning, Parameter Analysis, NUREG/CR-5512, Vol 3, Draft Report for Comment. Beyeler, W. E., W. A.
Hareland , F. A. Duran , T. J. Brown , E. Kalinina , D. P. Gallegos, and P. A. Davis, Sandia National Laboratories, Albuquerque , New Mexico, October 1999.
Dames and Moore 1994, North Plateau Groundwater Seepage Survey, Letter Report D&M :SPV:PJG :11B:0249. Dames and Moore, West Valley New York, August 15, 1994.
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WVDP PHASE 1 DECOMMISSIONING PLAN DOE 2004, Users Guide, RESRAD-BIOTA: A Tool for Implementing a Graded Approach to Biota Dose Evaluation , Version 1, DOE/EH0676. Environmental Assessment Division, Argonne National Laboratory, Argonne, Illinois, January 2004.
EPA 1997, Exposure Factors Handbook. National Center for Environmental Assessment, Office of Research and Development, U. S. Environmental Protection Agency, Washington , D.C ., 1997.
Hemann and Steiner 1999, 1998 Geoprobe Investigation of the Core Area of the North Plateau Groundwater Plume , WVDP-346, Revision 0. Hemann , M.R. .and R.E.
Steiner 11 , West Valley Nuclear Services Company, June 11 , 1999.
NRC 1977, Estimating Aquatic Dispersion of Effluents from Accidental and Routine Reactor Releases for the Purpose of Implementing Appendix /, Regulatory Guide 1.113, Rev. 1. U.S . Nuclear Regulatory Commission , Office of Standards Development, Washington , D.C., April 1977.
NRC 1997, Generic Environmental Impact Statement in Support of Rulemaking on Radiological Criteria for License Termination of NRG-Licensed Nuclear Facilities; Final Policy Statement. NUREG-1496, Vol. 1. U.S. Nuclear Regulatory Commission ,
Office of Regulatory Research , Division of Regulatory Applications; Washington ,
D.C., July 1997.
NRC 2000 , Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) ,
NUREG-1575, Revision 1. NRC, Washington , DC, August, 2000 . (Also EPA 4-2-R-97-016, Revision 1, U.S. Environmental Protection Agency and DOE-EH-0624, Revision 1, DOE)
NRC 2006, Consolidated NMSS Decommissioning Guidance: Characterization, Survey, and Determination of Radiological Criteria, Final Report, NUREG 1757 Volume 2, Revision 1. NRC, Office of Nuclear Material Safety and Safeguards, Washington ,
DC, September, 2006.
Price 2009, West Valley EIS/DP/an Calculation Package, Estimates of Human Health Impacts Due to a Sub-surface Source in the Vicinity of the Excavation of the Main Plant Process Building, Calculation DPlan-SAIC-JDP-003. Price, J., Science App lications International Corporation , Germantown , Maryland, October 2009.
Willgoose 2000, User Manual for SIBERIA (Version 8.10) , University of Newcastle, New South Wales, Australia , July 2000.
WVES and URS 2009, West Valley Demonstration Project Annual Site Environmental Report, Calendar Year 2008. West Valley Environmental Services and URS Group, Inc., West Valley , New York, September 2009 .
WVNSCO 1993a. Environmental Information Document Volume Ill Hydrology Part 4 Groundwater Hydrology and Geochemistry, WVDP-EIS-009 , Revision 0. West Valley Nuclear Services Company, West Valley, New York, February 19, 1993.
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WVDP PHASE 1 DECOMMISSIONING PLAN WVNSCO 1993b, Environmental Information Document Volume I, Geology, WVDP-EIS-004, Revision 0. West Valley Nuclear Services Company, West Valley, New York, April 1, 1993.
WVNSCO 1994, Environmental Information Document, Volume IV: Soils Characterization, WVDP-EIS-008, Revision 0. West Valley Nuclear Services Company, West Valley ,
New York, September 15, 1994.
WVNSCO and D&M 1997, Resource Conservation and Recovery Act Facility Investigation Report, Volume 4: Low-level Waste Treatmef)t Facility, West Valley Demonstration Project, West Valley, New York , WVDP-RFl-021 , Revision 0. West Valley Nuclear Services Company, West Valley, New York and Dames and Moore , Orchard Park, New York, January 17, 1997.
Yager 1987, Simulation of Groundwater Flow Near the Nuclear Reprocessing Facility at the Western New York Nuclear Service Center, Cattaraugus County, New York ,
Geological Survey Water Resources Investigations Report 85-4308 . Yager, R.M, U.S . Geological Survey, U.S. Department of Interior, Washington , D.C., 1987.
Yu , et al. 1993, Data Collection Handbook to Support Modeling the Impacts of Radioactive Material in Soil, ANL/EAIS -8. Yu , C., et al. , Environmental and Information Sciences Division , Argonne National Laboratory, Argonne , Illinois, April 1993.
Yu , et al. 2000 , Development of Probabilistic RESRAD 6.0 and RESRAD-BUILD 3.0 Computer Codes , NUREG/CR-6697, ANL/EAD/TM ~98. Yu , C., et al. ,
Environmental Assessment Division , Argonne National Laboratory, Argonne ,
Illinois, November 2000 .
Yu , et al. 2001 , User's Manual for RESRAD Version 6, ANL/EAD-4. Yu , C., et al. ,
Environmental Assessment Division , Argonne National Laboratory, Argonne ,
Illinois , July 2001.
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