ML102450690
ML102450690 | |
Person / Time | |
---|---|
Site: | Braidwood ![]() |
Issue date: | 12/20/2005 |
From: | Exelon Nuclear |
To: | Office of Information Services |
References | |
FOIA/PA-2010-0209 | |
Download: ML102450690 (44) | |
Text
X-z--,, el 1 Exe '
Nuclear
-;EA,4ý7 Braidwood Station Groundwater Tritium Investigation December 20, 2005
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Agenda Exelý5ns,\
Nuclear
- Introduction- Scott Humbard
- Braidwood Site Overview - John Moser
- Safety of the Public - John Moser
- Status of Investigation - Scott Sklenar
- Long Term Plan - John Moser
- Summary - John Moser 2
f Braidwood Site Overview Exe Iiiz:n I...
Nuclear o Approximately 4500 acre site with 2500 acre cooling lake
- Tritium generated in reactor coolant from reactor operation
- Circulating water system transfers heat to cooling lake Continuous make-up and blowdown between cooling lake and Kankakee River Vacuum breakers used in blowdown line to prevent damage due to water surges in pipe when flow changes 3
.i /
Braidwood Site Overview
-Nuclear e Liquid. effluent management
- No tritium (or other liquid radioactive effluents) being released into blowdown line flow until pipe confirmed to be leaktight
- liquid effluent storage capacity being supplemented with temporary storage tanks 4
A* N Safety of the Public Nuclear
- Groundwater sampling identified elevated concentrations of tritium in the shallow groundwater
- Drilled over 100 monitoring wells onsite and offsite to determine extent of tritium migration
- Tested 14 private wells of residents north (downgradient) of the site (pCi/L) private wells measured less than 142 picocuries per liter
. Thirteen °o\
- Three readings from one private well were 1151 1524 1367 pCi/L
- Calculated radiation associated with highest private well reading is 0.3 millirem per year
- Results of private well sample analysis have be n communicated to residents 5
N Status of Investigation Nuclear Regional Geology
" Fine grained uniform sand - ranges in thickness from 15 to 35 feet
" Regional clayey till - averages 20 feet thick
" Bedrock formations comprising shales, coal, silt stones, limestone, and sandstones
" Uppermost aquifers - uniform sand and bedroc (
sandstone Man-made Features
" Coal mining operations
- Borrow pits /ýV
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Status of Investigation Eeo.,o Nuclear Hydrology
" Shallow groundwater flows toward the north
" Geologic barriers exist to vertical downward migration
" Deep bedrock groundwater also flows to the north
- Interaction of groundwater with surface water bodies 7
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ffimm Status of Investigation kxeml o-nm Nuclear Extent of Tritium Plume
" Shallow water-bearing sand
" Surface water bodies
" Deeper water-bearing sand
- Bedrock aquifer 8
Status of Investigation txeli:n, Nuclear Potential Sources, Transport of Tritium
- Existing evidence indicates the source of the tritium is the blowdown line
- Further investigations focused to confirm whether source is current leak(s), historic spills, or a combination Potential transport mechanisms
- Influence of pond on tritium transport
t-Status of Investigation n,,'A Nuclear Regional Investigation
- Historical review of coal mines and local quarries
- Review of historical aerial photographs e Survey of public and private drinking water systems north of site
- Development of regional hydrogeologic cross-sections 10
7 Status of Investigation Exe I nsm Nuclear Field Investigation
- Two onsite shallow sand wells
- 21 onsite deeper sand wells o 10 offsite shallow wells
- 12 offsite deep wells
- Synoptic round of water level measurements
- Comprehensive round of groundwater samples
- Will sample selected wells weekly
- Installing staff gauges in surface water bodies 11
- "
Status of Investigation Nuclear Blowdown Line Integrity
- Periodic surveillance of blowdown line vacuum breaker valves to verify no leakage
- December 9, 2005 surveillance confirmed no leakage
& Special acoustic monitoring test being performed on blowdown pipe to determine if pipe has underground leak
- Sensor ("microphone") attached to umbilical cable inserted in pipe; water flow pulls sensor through pipe to identify location of leak
- Test scheduled to be completed December 30, 2005 12
/
Status of Investigation Nuclear
" Data evaluation and reporting
- Evaluate data from field investigations and pipeline integrity test in order to:
- Determine source or sources
- Define lateral and vertical extent of plume
- Evaluate risk to human health and environment
- Develop appropriate future actions including monitoring
" Prepare summary documents of evaluations for regulatory review
- Establish periodic informational update meetings 13
I,---.
Long Term Plan E elo
- Nuclear Project underway to significantly reduce overall liquid tritium discharge from Braidwood
- Reduce tritium production through enhanced reactor core design 7 Optimize management of tritium inventory in reactor operations
- Enhance gaseous release capability
- Research tritium separation technology 14
Exelon B ddeiNude-ar Braiedwood Generating Station
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Radiation and Sources of Internal Dose Eli A. Port, CHP, CIH, P.E...
° An isotope of Hydrogen with two neutrons 2
How much H-3 is in the environment ?
- Cosmic rays produce 4,000,000 curies per year
- The total tritium in the environment is about 70,000,000 curies 4
arial Radiloactive Mtra QuniYof e Traditional u. .ocurie (pCt)
- Sub-unit- P!
- oComparison -12 Ci or a trillionth of a curie
-1 pCi 0 5
Sources of Radiation Natural 292 mrem
- Radon 200 mrem
- Cosmic ray 27 mrem
- Rocks and Soil 30 mrem
- Food and drink 35 mrem AverageTotal
Background
Radiation Man-made 65 mrem 357 mrem/year
- x-rays 40 mrem
- Nuclear med 13 mrem
- Consumer products 10 mrem
- Research 2 mrem 6
EPA Drinking Water Limit
- 20,000 pCi/I
- At this concentration, drinking 2 liters of water per day will result in a dose 4 mrem per year 7
Tritium in Well Water
- The highest concentration of tritium found in a well supplying drinking water is:
1,524 pCi/i 9 At this concentration, drinking 2 liters per day will result in 0.3 mrem per year.
8
Other Sources of Internal Dose 9
Dose from C-14
" The concentration of C-14 in natural carbon is 7 pCi/g
- Human Reference Diet = 300 g carbon/day
" Resulting in 1.9 mrem per year from carbon in food 10
7 N
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Potassium-40 (K-40) Dose
- Human Diet = 2 -.5 g/day
- Resulting in a K-40 dose between 10 mrem per year and 25 mrem per year 11
Annual Dose from K-40 In Specific Foods 0 1 banana per day = 2.6 mrem
- 1 8 oz. glass of orange juice per day = 2.5 mrem
- 1 medium baked potato per day = 4.3 mrem 1 cup Total raisin bran per day = 1.8 mrem
° 1 double burger sandwich per day = 2.9 mrem
- 1 large order of fries per day = 4.7 mrem
- 1 cup cantaloupe per week = 0.4 mrem
° 1 cup spinach per week =0.6 mrem
° 6 oz halibut fillet per week = 0.7 mrem 12
Smoking
- The average annual dose from Po-210 in tobacco.is 2000 mrem
- Hot spots (bronchial bifurcations) may
.receive up to 16,000 mrem per year 13
Biological Effects
- We know that radiation may cause damage in tissue
- No effects have been found from low doses, under 10,000 mrem
° To be conservative, limits are set below doses where effects -are detected 14
- I-N Questions 99 P
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