ML082690407
| ML082690407 | |
| Person / Time | |
|---|---|
| Site: | Plum Brook File:National Aeronautics and Space Administration icon.png |
| Issue date: | 09/03/2008 |
| From: | US National Aeronautics & Space Admin (NASA) |
| To: | NRC/FSME/DWMEP |
| References | |
| Download: ML082690407 (57) | |
Text
J National Aeronautics and Space Administration NASA Glenn Research Center Plum Brook Reactor Facility Off Site Contamination Public Meeting with the NRC 9-3-08 www-naulgov National Aeronautics and Space Administration A genda
" Background on discovery of contamination offsite in Plum Brook, and subsequent characterization efforts.
- Keith Peecook, PBRF Program Manager, NASA
- Presentation of Plum Brook Dose Analysis results
- Bruce Mann, CHP, FSS Technical Consultant, PBOSG
- NASA proposal for demonstrating compliance with NRC regulations for offsite contamination
- John Thomas, Licensing Engineer, SAIC Bill Stoner, Project RSO, SAIC
- Questions and Discussion All
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A National Aeronautics and Space Administration Background of Plum Brook Contamination and Characterization Efforts Keith Peecook wwwnass.gov, 2
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National Aeronautics and Space Administration Discovery of Off Site Contamination
- In August of 2005, during routine characterization surveys, Cesium-137 was discovered in the sediment of Plum Brook, an offsite stream that was part of the normal discharge path for 'clean' process water during the operating days.
- The levels were low enough that environmental monitoring performed over the years did not detect them, but once FSS sensitivity level instruments were used the cesium was detectable.
m nasagon' National Aeronautics and Space Administration Scoping Sampling Efforts
- Scoping samples were collected from publicly accessible points in Plum Brook between the NASA fence and Sandusky Bay.
- Isolated 'elevated' readings found averaged 2 to 3 pCi/gm, though a few readings in the 20 - 30 pCi/gm range were found.
- Contamination was found to a depth of 18" in a few locations.
- The isotopic mix (Cs-1 37 and Co-60) was consistent with Pentolite Ditch, nearer to the PBRF outfall
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National Aeronautics and Space Administration Scoping Sampling Efforts, Continued
" While the levels found did not appear to present an immediate risk to the public or the workers, NASA concluded that
- There was contamination that was ours (licensed material)
- It was above background.
- Further sampling and understanding were required
- NASA informed the NRC of its findings and developed a more extensive scoping sampling plan.
- NASA also shared this information with the Ohio Department of Health, Bureau of Radiation Protection, the Ohio EPA, the Ohio Emergency Management Agency, the Erie County Emergency Management Agency, and the Erie County Health Commissioner.
" NASA also responded to questions from Workgroup members and provided a brief update. The information was also posted on our Telephone Information line.
ww.rnas~gOV National Aeronautics and Space Administration Plum Brook Sample Locations SP-1 Weir Outfall SP-2 Pentolite Road Pipe Ouffall a....
SP-3 Columbus Road SP-4 Clark Road SP-5 Taylor Brook Road SP-6 Bogart Road SP-07 Galloway Road SP-08 Hull Road SP-09 Perkins Avenue
- SP-14 Scheid Road SP-15 Wastewater Treatment Site Upstream SP-16 Wastewater Treatment Site Downstream anaW.
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dtitiinSample Results Plum Brook Sample Results 40.00 35.00 30.00 25.00 20.00
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National Aeronautics and Space Administration S
Characterization Sampling
- Scoping sample results showed there was detectable contamination above background all the way to Sandusky Bay.
" The question remained as to how extensive was the spread, and what were the levels involved?
- In September 2005 NASA began a characterization sampling effort, with the initial piece being from the NASA fenceline downstream to SR 2, a distance of about 1 1/4 mile.
- NASA requested and received written permission from private property owners to access their property
- Both ODH and the NRC collected split samples U*w. nasa~gov National Aeronautics and Space Administrationa Public Meeting - Jan 2006
- In January 2006, while sampling was going on, Cong Marcy Kaptur (D - Toledo) called for a public meeting with senior members of NASA and the NRC
" NASA presented data available at that point (Area A),
and explained its future sampling plans NASA committed to doing what was necessary to completely define the problem and to protect the public NRC committed to consider the contamination in Plum Brook to be part of the PBRF decommissioning, and to not terminate NASA's licenses until Plum Brook was properly addressed
" Cong Kaptur expressed her satisfaction with the status of activities and directed NASA to keep her office informed of the results Www.nasigof 4
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ý Sample locations nm
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National Aeronautics and Space Administration Random Sample Results to date Preliminary Sample Resulta by Location Section A, Phase 1 Cs-137 (pCUg) 40 30 20 01_ %-t 0 16"-24' Proposed On-site Clean-up Leel = 1171 pCi/g11 SV 14 4
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National Aeronautics and Space Administration Targeted Area Sample Results to date Preliminary Sample Results by Location Section A, Phase 2 Cs-137 (pCUg)
OL I.. LLII 1 L WWW.n-s goy National Aeronautics and Spame Administrainona Section A-E Sample Results
- Sample collection was completed in March 2006, and analysis was completed in early April 2006
- Results were shared with the NRC, ODH, and other interested government bodies, as well as all the property owners along Plum Brook where samples were taken.
- A consistent pattern was found of isolated spots with elevated readings, but with most of the readings being considerably lower.
" The average reading for each Section was approximately 1 pCi/gm.
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National Aeronautics and Space Administration Additional Investigation NASA sought guidance from Haag Environmental Company, a local company with hydrogeologic expertise, to better understand the hydrodynamics of Plum Brook, and from that be able to explain:
- How the cesium moved downstream over time
- How the cesium was physically distributed
- What was the explanation for the pattern being seen
- Where else besides the bottom of Plum Brook needed to be sampled ww.na&gm n
National Aeronautics and Spew Administrationa Haag Hydrogeologic Insight
" Cesium binds almost permanently with clay sediment Pentolite Ditch is an excellent source of clay silt If you find where the sediment moved to, you find the cesium
- The silt moves constantly downstream, depositing, eroding, and redepositing
" Deposits, or cells, tend to be isolated, relatively small in physical size, and are often buried under several inches to several feet of clean sediment, with only the edge next to the stream exposed They will eventually be uncovered by erosion and again move downstream
- Stream course has shifted over time www.nasagov 12
National Aeronautics and Space Administration Haag Insight, Continued 90% of the motion of silt occurs during 10% of the time, when water is high and moving swiftly Highest Cs levels in plant water were during 1967 to early 1968 due to a small fuel element leak Discharge levels did not exceed limits, but were higher than during any other time in the plants 10 year operating history
- The heaviest rainfall in recent history (11" in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) hit in July 1968, likely spreading the sediment from Pentolite Ditch far downstream.
Big question in Haag's mind was where was the delta, or largest downstream concentration of cesium bearing silt, today?
WWW fAAW11.gon National Aeronautics and Space Administration Areas to Characterize Haag identified the following areas to be characterized:
Groundwater Upper Meander Section Lower Meander Section Flood plain
- Wetland/mouth of Plum Brook
- Sandusky Bay Ponds along Plum Brook narWa.go.
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National Aeronautics and Space Administration d
b-Plum Brook Characterization n5&gov ý,
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National Aeronautics and Space Administration Summary of Results After a total of 2 years of characterization sampling (3,000 samples from 1,200 locations) and analysis, NASA determined the following:
- Average level of cesium (including biased samples) in Plum Brook less than 2 pCi/gm
- Average level of cesium in Sandusky Bay (water supply for City of Sandusky) indistinguishable from background
- Delta, such as it is, appears to be in the Putnam State Marsh, Y4 mile upstream of the bay
- Samples taken (upon request by neighbors) in back yards and gardens (where Plum Brook sediment had been used as fill) proved to be indistinguishable from background
~wmrnfaaigm National Aeronautics and Space Administration Summary of Results, Continued
- All results were reported in writing to private property owners - no requests for clarification or additional information were received.
" Formal reports written for each area, copies submitted to all regulatory agencies and Community Work Group members, made available to public at our local information bank and on line
- Summary report provided in March 2008 to Cong Marcy Kaptur's office, in keeping with a promise made at the public meeting in January 2006 - no response as of this date.
VAV.nasa.gov3 16
National Aeronautics and Space Administration W here are we now?
" We now have a very good understanding of where the contamination is, what the levels are, the hydrology, how it will likely move in the future, and current and projected land use for the various sections of Plum Brook
" The Resident Farmer scenario is not representative of the conditions along Plum Brook.
- NASA performed dose analysis to estimate doses to members of the public that could be exposed to cesium in Plum Brook sediments.
ww.naaa.gov National Aeronautics and Space Administration Dose Assessment for Plum Brook Sediments
- Dust, ish External Presentation to NASA-NRC Meeting on Plum Brook Dose Modeling Analysis Sept 3, 2008 WhWWmoogO 17
National Aeronautics and Space Administration Acknowledgments
- Keith Peecook, NASA Program Manager - project objectives
- Bob Haag, Haag Environmental - consulting hydrologist
" Bruce Mann, PBOSG Consultant - principal investigator
" Technical assistance:
o ANL-EAD - RESRAD questions o Gerald Matisoff, Dept of Geological Sciences, Case-Western Reserve Univ. - Sedimentation processes and Cs-1 37 deposition o Keith Eckerman, Oak Ridge National Lab. - age-dependent dose factors National Aeronautics and Space Administration Outline
- Why are we doing this?
- Plum BrookTour
- Dose Modeling Objectives
- Technical Approach
- Scenario Descriptions
- Key Parameters
- Dose Results
" Age-dependent Dose
- Alternatives for compliance with dose criterion
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National Aeronautics and Space Administration Why Are We Doing This?
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" Radiological surveys were performed by NASA along Plum Brook in Sandusky Ohio in support of Plum Brook Reactor Facility (PBRF) Decommissioning.
- Cesium-1 37 was measured in samples of sediment from several locations along the stream between the PBRF and Sandusky Bay.
- Concentrations of Cs-137 in sediment ranged from non-detectable to levels in excess of the clean-up criterion for surface soil on the PBRF site (14.7 pCi/g).
- Comprehensive sampling was followed by dose modeling to estimate doses to people in the vicinity of the Plum Brook wwwrta".gn National Aeronautics and Space Administration PLUM Brook Tour
- Total stream course length - 7 miles
" Watershed area of 6.4 square miles www.naao.gov.
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National Aeronautics and Space Administration View of Sandusky, Ohio Showing Plum Brook Facility SnaSaMg9Y.o National Aeronautics and Space Administration Originates in Farmland South of the Plum Brook Facility naaagov9m 20
A4 National Aeronautics and Space Administration Terminates in Sandusky Bay at Putnam Nature Preserve nASSILWN National Aeronautics and Space Administration Crosses Facility from South to North 21
National Aeronautics and Space Administration Pentolite Ditch joins Plum Brook near Northern Boundary of the Facility wWW1,4n11aa,11.0 National Aeronautics and Space Administration lo Lower Stream Rural Area North of PBRF
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National Aeronautics and Space Administration A
Milan Ave Commercial Area WIW.nIIIIIIII.goV.~
National Aeronautics and Space Administration Lower Stream Section Residential Area 9
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National Aemnauaics and Space Administration Traverses Plum Brook Country Club from South to North WWW naSaB 4?n National Aeronautics and Space Administnation o
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View of Plum Brook in PBCC Golf Course wwwnasw~om 24
National Aeronautics and Space Administration Flood Plain and River Mouth ww.naza.gov.
National Aeronautics and Space Administration Stream Mouth - looking North from Route 6 wwnaseagov.
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National Aeronautics and Space Administration Dose Modeling Objectives
" Estimate Dose to Members of the Public using Realistic Exposure Scenarios
" Provide technical basis for demonstrating compliance with 10CFR20 Subpart E dose criterion.
WWnmW"gov" National Aeronautics and Space Administration Dose Modeling Approach
- RESRAD - same code used to obtain soil DCGLs for Plum Brook Reactor Facility (14.7 pCi/g, Cs-137)
" Used Resident Farmer Scenario
- Approach was modified for Assessment of Dose from Plum Brook Sediments www.nhau.gO 26
National Aeronautics and Space Administration Modeling Overview
" Conceptual site model developed for Plum Brook
" Exposure scenarios developed to describe conditions where members of the public could be exposed to Cs-1 37 contaminated sediments
- Different from Resident Farmer scenario used to obtain PBRF soil DCGLs
- Within the envelope of scenarios developed by NRC for site evaluations
- vmnasagov National Aeronautics and Space Administration Conceptual Site Model Seeks to Answer the Following Questions
- What is the impacted environment?
- What is the source of contamination?
- How did it get there?
- Where is it going?
" How are people exposed?
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National Aeronautics and Space Administration Conceptual Site Model
- Overview
- Plum Brook Watershed
- Geologic Setting
" Stream Hydrology
- Surface Features
- Land Use and Demographics
- Sediment Transport
- Distribution of Sediments
-~.nasa.Vwo National Aeronautics and Space Administration C S M ve ri
" Plum Brook originates in farmland south of 6400 acre Plum Brook Station
- Area of concern is the watershed (drainage area) extending from Station Northern Boundary to Sandusky Bay
" Stream-course distance about four miles ww~n*rnpv 28
National Aeronautics and Space Administration Plum Brook Watershed
- Plum Brook Watershed area N of Station is 1.6 square miles
- Drains portions of Perkins and Huron Townships, Erie County on outskirts of City of Sandusky, OH
" Gently slopping terrain from elevation 620 ft. at Station N boundary to 570 ft at Sandusky Bay
-W.nasaWgov National Aeronautics and Space Adrministratlon Geologic Setting
- Surface glacial till underlain by shale, mudstone and limestone formations
" Glacial till - dense clay, unconsolidated silt, sand and gravels
" Glacial till ranges from 10 to 20 ft thick
- Stream ravine confined to surface deposits and thin shale and limestone beds
- The thin beds overlay older limestone formations up to several hundred feet thick nasagonQ
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National Aeronautics and Space Administration Geologic Setting, Continued
" Regional aquifer is Delaware Limestone
- Bedded-fractured formation ranging from 15 to 20 meters thick in vicinity of Sandusky
- Underlain by older limestone formations up to several hundred meters thick
" Average depth to regional ground water table is about 40 ft in vicinity of PBRF
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National Aeronantics and Space Administration Stream Hydrology
- Perennial stream
- Does not appear to be in direct contact with regional groundwater table
- Contacts local near-surface water tables at several locations
" Flow is highly variable, with minimum of a few cfs up to 100's of cfs (or more) during storm events
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National Aeronautics and Space Administration Stream Hydrology, Continued
- Average annual flow ranges from 2.3 cfs at PBRF N boundary to 5.5 cfs near stream mouth
- Limited public use of Plum Brook water (PBCC golf course watering)
- Three principal flow regimes:
- Meandering stream
- Upper stream-flood plain
- River mouth-wetlands WW.nasa.QoV.
National Aeronautics and Space Administration Plum Brook at Pentolite Ditch Aug 2008 WW.nWaaagW 31
a National Aernnautics and Space Administration Plum Brook at Pentolite Ditch Feb 2008 ww.nasa~gov.
National Aeronautics and Spae Adminintration Surface Features
" Most of the 4 mile stream course (> 75%) is in a "natural state"
- Channel ranges from 10 to 15 ft in width in meandering sections and water surface is normally 5 to 8 ft below bank top
- Stream banks are heavily vegetated - fallen trees create debris dams
" Modifications include culverts and concrete channels at overpasses, storm drain outfalls and landscaped banks ww.naea gov.
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National Aeronautics and Space Administration Typical Stream Bank in Meander Section
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National Aeronautics and Space Administration Debris Dam in Meander Section
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Natonal AemaAiýcs and Space Administration Stream Course Sediments
" Stream channel bottom and banks are composed mostly of muds and sediments
" High fraction of silts, clays (illite) and fines
- Principal sources are:
- Soil erosion and surface runoff from agricultural land
- Unconsolidated glacial till in stream banks
- sediment transport from upstream
- Annual sediment input estimated to be 100 to 150 MT
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Nainl and Space Admin t tin L a n d U s e
" Land use controlled by local zoning - a mixture of agricultural, residential, commercial, government and recreational
- Overall characterized as medium-to-low density development
- Even though about 1.5 miles of the stream course is in areas zoned residential, only 45 residences border the stream (dwelling within 100 ft.)
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National Aeronai and Space Administration Demographics 0 Erie County average population density is 312 persons per square mile
- 60% of watershed north of PBRF is non-residential
- Estimated average population density in near-stream environs is < 25 persons per square mile naaM2&gc National Aeronautics and Space Administration Sediment Transport
" Cs-137 released from PBRF in liquid effluents during facility operation 1963-73
- Estimated total activity released: 5 to 7 millicuries
" Releases were mostly in soluble form
- Released to Pentolite ditch - a man-made waterway
- Pentolite Ditch joins Plum Brook - 1600 ft.
downstream from PBRF release point WWflrnQgM 35
Natioal Aeronautti andJ Space Administration Sediment Transport, Continued
" Cs-137 rapidly adsorbed onto sediments (clays) in Pentolite ditch
- Under normal flow most Cs-bearing sediments settle out onto stream bottoms
- Some transport due to movement of suspended particles by stream flow
" Most movement of sediments occurs during high-flow conditions - major flood events occurred in 1966 and 1969
- Wna=8gW 11 Natinal Aeonautics and Space Administration Distribution of Contaminated Sediments
" Cs-bearing sediments are non-uniformly distributed
" In meander sections, most contaminated sediments are deposited within the stream banks
- Wider lateral distribution in flood plain
- In "back-water" areas created during flood events, sediments could have moved beyond stream banks nafs.agotn 36
National Aeronautics and Space Administration Distribution, Continued
" Cs-137 measured in samples of Plum Brook collected at over 1200 locations from Pentolite Ditch to Sandusky Bay
- Concentrations ranged from "less than detectable" (< -
0.02 pCi/g) to 72 pCi/g (at one location)
- Cs-1 37 is below detection limits in Plum Brook water samples W"wnA4114.ft1 National Aeronautics and Space Administration Summary of Sediment Sample Results (random-systematic samples)
No. of Cs-137 Concentration (pCi/g)
Section Locations Sampled Range Average 1 & 2 -Upper and Lower Stream Meander 621 24E-02 to 72.4 1.16 Sections 3 - Upper Flood Plain 238 5.8E-02 to 14.2 0.69 4 - Lower Flood Plain and Mouth 44 3.6E-02 to 20.6 0.73 INasllagonr.
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National Aeronautics and Space Administration Fate of Cs-bearing Sediments
" Cs-1 37 attached to illite-clay sediment particles -
highly retentive, Kd - 20,000 ml/g
- New sediments continually enter the Plum Brook -
over time Cs-bearing sediments are "buried"
- The highest average concentrations are found in the 0-to-6 in layer, but most of the total Cs-1 37 inventory lies below 6 in.
" Environmental Cs-1 37 appears to exhibit an effective removal half-life of - 8 to 10 y.
w-wnamagov National Aeronautics and Space Administration Environmental Cs-137
" Releases to Plum Brook from PBRF coexist with Cs-1 37 from atmospheric fallout
- Fallout Cesium in particulate form was bound to atmospheric particulates and aerosols
- Cumulative fallout deposition - 140 mCi/km2 or 360 mCi per square mile (at 40 to 50 deg N Latitude)
-~ 0.6 Ci deposited in the watershed north of the PBRF (1.6 sq. mi.)
- Resulted in average soil concentration of - 0.7 pCi/g (0 to 15 cm layer) in the mid-to-late 1960's.
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National AeronauW"ce and Space Adminisntration Environmental Cs-137, Continued
- Soil particles containing Cs-137 are transported by surface runoff-soil erosion
- Deposited as sediments in surface water bodies
- Cs-bearing sediments accumulate in lakes, reservoirs and estuaries - highest concentrations observed at depth (30+ years after peak deposition)
- Example: 6 pCi/g measured in Ballville Dam Reservoir sediments, Sandusky River near Fremont OH (peak concentration at - 1 ft depth)
,A.no" goft National Aeronautifs and Space Adttinistration Dose from Fallout Cs-1 37
" Average dose to individuals in the US was approximately 8 mrem/y in 1965 (peak year)
" Declined to about 0.5 mrem/y in 2000.
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National Aermnautics and Space Adtinistration Plum Brook Divided Into "Stream Sections" for Exposure Scenarios
- Upper Stream - from Pentolite Ditch to State Rt 2
- Lower Stream - from State Rt 2 to Plum Brook Country Club central area
" Upper Flood Plain - from Country Club central area to US Rt6
- Lower Flood Plain/River Mouth - from US Rt 6 to Sandusky Bay
.nas&qw National Aeronautics and Space Administration Stream Section Summary Stream Section Course (mi)
Land Use (zoning)
Public Access 1 -Upper Stream 1.6 30% Residential Private property, or (meander) 30% Agricultural access by permission 30% Commercial only 10% GovernmentlMuni.
2 - Lower Stream 1
60% Residential Private property, or (meander) 20% GovemmentlMuni. 20%
access by permission Commercial - recreational (Golf only Club) 3 - Upper Flood Plain 0.85 60% Commercial - recreational Private property, or (Golf Club) access by permission 40% Agricultural only 4 - Lower Flood Plain 0.55 100% Erie Metro Park Controlled.
and Mouth public access Wnha.gMO 40
National Aeronautics and Space Administration Plum Brook Exposure Scenarios
" Stream environments matched with land use &
demographics
" Dose receptors are "average members of critical group" for each stream section
- Scenarios:
- Suburban Gardener
- Streamside Resident
- Country Club Maintenance Worker
- Recreational user w#~wnA".gW.
and Space Administratinr
" Residence located in upper stream meander section
- Sediments excavated from bank of Plum Brook used to supplement garden soil
- Resident receives exposure from working in garden and consuming home-grown vegetables
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National Aeronautics and Space Administrationa Setting for Suburban Gardener Scenario W
WWW.nha.gov National Aeronautics and Space Administration Brook Side Resident
" Located in lower meander stream section
" Source is assumed to be sediments deposited in flood back water area - home subsequently constructed
" Resident exposed by occupying portion of house located above contaminated sediments and from yard work outdoors in contaminated area nasagonM 42
National Aeronautics and Space Administration Setting for Brookside Resident Scenario nasa1111.gov.
National Aeronautics and Space Administration Country Club Maintenance Worker
- Located on Plum Brook Country Club grounds
- Source is sediments excavated from ponds that are intermittently connected to Plum Brook -
placed along golf course pathway
- Maintenance worker is exposed by traveling on pathway and maintaining adjacent landscaping VrW~naaagCV 43
National Aeronautics and Space Administration CC Maintenance Worker Scenario Setting WiWWnM.PgV 8
National Aeronautics and Space Administration Recreationist
° Located in stream mouth - wetlands section
" Source is sediments in stream bed and adjacent to stream
" Recreational user receives exposure from occupying stream and stream bank and from consuming fish caught in the stream W%.nas.g0V 44
National Aeronautics and Space Administration Setting for Recreationist Scenario wwnasA~gov.
National Aeronautics and Space Administration Exposure Pathways
" Direct exposure (all scenarios)
- Inhalation of suspended sediments (all scenarios)
" Direct ingestion of sediments from incidental contact (all scenarios)
- Consumption of garden vegetables (Suburban Gardner)
- Consumption of fish (Recreationist) wwwnaso.gov.
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National Aeronautics and Spacm Adainnstration Dose Model Key Parameters Outdoor Indoor Area of Thickness of Occupancy Occupancy Contaminated Contaminated Scenario (h/y)
(h/y)
Zone (M
- 2)
Zone (mn) 0.076 Suburban Gardner 123 NA 186 (3 in.)
0.076 Brook side Resident 80 1096 186 (3 in.)
Country Club 450 NA 600 0.076 Maintenance Worker (3 in.)
Natural Area o0.152 Recreationist 105 NA 270,000 (6 in.)
PBRF Resident 964 5786 109100 1
Farmer www.nm.govm National Aeronautics and Space Administration Dose Modeling Results Dose Fraction by Pathway (%)
Scenario Ds (mrem/y per pCi/g)
Direct Food Consumption Suburban Gardner 0.04 64 36 (vegetables)
Brook Side Resident 0.17 99.9 NA Country Club Worker 0.10 99.9 NA 67 Recreationist 0.11 33(ih (fish)
PBRF Resident 1.7 82 18 Farmer (Plants, meat, milk) www.9nmgov 46
National Aeronautics and Space Administration Naioa Afnatisan pae Sensitivity Analysis Results Rank Scenario Area of Distribution Occupancy Contaminated Contaminated Dietary Coef.,
Fraction Zone Thickness Zone Suburban 1
Gardner Brook side 1NA NA NA Resident Country Club Maintenance 2
NA NA NA Worker Natural Area Recreationist ww.nas.gov National Aeronautics and Space Administration Plum Brook Vs PBRF Scenarios
- Reduced Suite of Exposure Pathways
" Water Pathways are not important dose contributors VA".nasago 47
National Aeronautics and Space Administration I
Dose Modeling Results
" Highest dose - Brook-side Resident: 0.17 mrem/y per pCi/g
" Compares to PBRF Resident Farmer Dose from Cs-137: 1.7 mrem/y per pCi/g
- Average Cs-137 concentration in Plum Brook sediments - 1 pCi/g
" Therefore, doses reported per pCi/g are good estimate of the doses received by "average member of the critical group" for each scenario w*W.naaa.gW National Aeronautics and Space Administration Age-Dependent Dose from Cs-1 37
" Doses to age groups were calculated using ICRP-72 dose factors recently added to RESRAD libraries
- Special scenario developed for children - playground scenario, 450 hours0.00521 days <br />0.125 hours <br />7.440476e-4 weeks <br />1.71225e-4 months <br /> per year occupancy
- Highest calculated dose was to a young child (1 to 5 yr-old): 0.13 mrem/y per pCi/g Cs-1 37 nrilwna".lgiv 48
National Aeronautics and Space Administration Dose from Co-60 and Sr-90 Dose (mrem/y per pCilg)
Radionuclide Scenario Probabilistic mean and standard deviation Co-60 Brook-side 6.96E-01 6.79 +/- 7.08 E-01 Resident Suburban Sr-90 Garden 3.10E-01 3.13 +/- 2.81 E-01 Gardener
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National Aeronautics and Space Administration Summary and Conclusions
- Realistic but conservative exposure scenarios were developed for estimating dose to members of the public from Cs-1 37 in Plum Brook Sediments
- Highest calculated dose is < 0.2 mrem/y
- Indistinguishable from background radiation dose and less than dose from Cs-1 37 in the environment from weapons testing fallout ww.nasa.gov 49
National Aeronautics and Space Administration Alternatives for Compliance with Dose Criterion
" Standard MARSSIM approach - establish DCGLs and perform FSS of impacted area
" Alternative approach - characterize and perform dose assessment (NUREG-1757, V2 Sec. 2.5) wwwnaw.om National Aeronautics and Space Administration Standard Approach - Potential DCGLs DCGL for Dose Criteria Values (pCi/g)
DCGL 3
10 15 25 mrem/y mrem/y mrem/y mrem/y mrem/y average concentration 5.8 17.3 67.6 86.4 143.9 (DCGLw) elevated area concentration (DCGLEMC 68.2 204.5 681.7 1022 1704 example - one M 2) w ww.ras.gov im 50
National Aeronauitics, and Space Administration Characterize and Dose Model
- Compile and summarize results from extensive Plum Brook sediment sampling campaigns
- Calculate doses from realistic exposure scenarios using RESRAD
- Confirmatory survey after Pentolite Ditch remediation
- Environmental TLD study WW.nAsa.WW National Aeronautics and Space Administration Demonstrating Compliance with NRC Standards for Residual Licensed Material in Areas Outside the Plum Brook Reactor Facility wwnalagon 51
National Aeronautics and Space Administration F
CURRENT FSSP APPROACH
- The currently approved FSSP applies a MARSSIM based DCGLIFSS approach to demonstrating compliance with the release criteria of 10CFR20.1402.
" The FSSP was submitted for NRC approval in May 2006. It was revised by adding additional discussion of a Background Reference Area in February 2007.
- The FSSP was approved by the NRC by License Amendment issued in March 2008.
- Currently approved FSSP contains DCGL's for surface soil.
- The DCGL's are based on the assumption that the activity is distributed throughout the top one meter (contamination zone) of the entire survey unit.
WWW.1%MgWc National Aeronautics and Space Administration CURRENT FSSP APPROACH, Continued
" The DCGL's were developed using the RESRAD Model and dose pathway analyses for a Resident Farmer Scenario.
- Section 3.4 of the FSSP states, "The DCGL for sediment (e.g., stream or ditch silt) will be the same as the surface soil."
- At the time that this was written, characterization studies of Plum Brook were not complete and the approach to addressing residual licensed material in Plum Brook was not addressed in the FSSP other than in this single statement.
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National Aeronautics and Space Administration Proposed Approach to Residual Activity in Plum Brook The DCGL/FSS approach to be used on-site is not appropriate for the environmental areas in and along Plum Brook:
) The extent and meandering nature of the environmental area is not conducive to laying out MARSSIM type survey units.
The residual activity is highly non-uniformly distributed.
The residual activity is not evenly distributed throughout the top one meter of soil as modeled for land areas on site.
The nature of the area as regard to its current and potential future uses does not fit the Resident Farmer scenario.
The Plum Brook topography is not conducive to performance of FSS as described by MARSSIM for open land areas.
New technical procedures would be required and the cost of FSS would be significant.
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National Aeronautics and Space Administration Proposed Approach to Residual Activity in Plum Brook, Continued
- NASA proposes to use a dose assessment approach to demonstrate that the environmental areas in and along Plum Brook are in compliance with the dose criteria of 10CFR20.1402.
- This method, used in lieu of the MARSSIM based DCGL/FSS methodology is consistent with the methodology described in Section 2.5 of NUREG-1757, Volume 2.
" The end result of this approach is the same as the end result of a DCGL/FSS approach - a dose to the AMCG of less than 25 mrem per year.
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National Aeronautics and Space Administration Proposed Approach to Residual Activity in Plum Brook, Continued Using the dose assessment approach allows localized residual activity that exceeds the on-site soil DCGL's presented in the tables in the current FSSP:
The dose assessment methodology accounts for the small localized "spots".
This is comparable to the DCGL/FSS approach where MARSSIM has provisions for localized areas of elevated activity and the application of Area Factors.
ww n".161111.0 10 National Aeronautics and Space Administration Proposed Approach to Residual Activity in Plum Brook, Continued This approach is appropriate for the environmental areas:
The residual activity has been quantified and bounded by the characterization studies performed to date.
- The sample and survey data is documented in the site's Survey Request (SR) program prescribed by our Characterization and FSS Procedures.
o-Documentation is available describes the hydrogeology, methodology used in sampling, and analytical results.
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National Aeronautcs and Space Administration Proposed Approach to Residual Activity in Plum Brook, Continued Area specific dose pathway analyses have been performed for the area using methodology that is consistent with that used in developing DCGL's for the onsite areas (i.e., RESRAD Model).
The dose pathway analyses have been submitted to the NRC in the form of two separate Technical Basis Documents.
This approach is as protective of the public as the DCGL/FSS methodology used on-site.
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National Aeroautics and Space Administration a
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Proposed FSSP Revisions
- The FSSP will be revised to clarify that the surface and subsurface DCGL's presented in the tables apply to areas within the Plum Brook Station boundaries-this includes Pentolite Ditch.
- The dose model approach will be applied to areas outside of Plum Brook Station.
" The DCGL/FSS approach will be used for any area within the boundaries of Plum Brook Station.
- A brief discussion of the Dose Assessment approach will be incorporated into the FSSP.
- The FSSP will refer to the reports of the Plum Brook Characterization studies rather than incorporate all of the characterization data from those studies.
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National Aeronaotics and Space Administration Proposed FSSP Revisions, Continued
" The FSSP will reference the two Technical Basis Documents that present the dose modeling studies.
- The revised FSSP will allow use of the dose assessment approach for other off-site environmental areas in the unlikely event that additional environmental areas are determined to be contaminated with licensed material.
- The revised FSSP will not include specific DCGL's for Plum Brook, rather, it will reflect dose assessment of the residual activity.
ww~altna.gcv National Aeronautics and Space Administration License Issues
" Do the proposed revisions to the FSSP constitute a change that requires NRC approval?
- License Condition 3.A.1 requires NRC approval if a change to the FSSP:
, Requires Commission approval pursuant to 10 CFR 50.59;
), Reduces the coverage requirements for scan measurements;
> Increases the derived concentration guideline level and related minimum detectable concentrations (for both scan and fixed measurement methods);
>, Uses a statistical test other than the Sign test or the Wilcoxon Rank Sum test for evaluation of the final status survey; Results in significant environmental impacts not previously reviewed; w.tnauwgm 56
4.
National Aeronautics and Spame Administration License Issues, Continued License Condition 3.A.1 requires NRC approval if a change to the FSSP (Continued):
) Increases the radioactivity level, relative to the applicable derived concentration guideline level, at which an investigation occurs;
)i Increases the Type I decision error;
) Decreases an area classification (i.e., impacted to unimpacted; Class 1 to Class 2; Class 2 to Class 3; Class 1 to Class 3).
" If NRC approval is required, is the only mechanism for approval an amendment to the license?
" What is the appropriate mechanism for addressing the residual activity in the environmental areas in the Final Status Survey Report and request for License Termination?
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