Tritium – The “Real” Background

& Other Items of Interest

John Doroski

Why?

• Several references contain misleadinginformation on weapons testing levels

• 2006 RETS-REMP Workshop, Ken Sejkora’spresentation on “Atmospheric Sources of Tritiumand Potential Implications”

• EPRI Report – “Review of Methods and Tools forEstimating Deposition of Tritium at NuclearPower Plants” (page 2-1)

• 1970 - 1990 REMP data (CY river water samples)not consistent with the above references

Outline

1. “Real Background”a. “Background Measurements”

EPA DataNYS DataHistorical REMP Data

b. Global cycling models

2. Source Terms

3. Airborne Effluent Samplinga. LLDs (NUREG 1301/1302)b. Grab Samplingc. Bubbler

4. Rainfall and Condensation

“Background” Measurements• EPA Data: epa.gov/narel/radnet/erd

H-3 MDC (95% probability, …) – 150 pCi/liter

Measurement Uncertainty Each measured value y is reported with an expandeduncertainty U = k uc(y), which is determined from the combined standard uncertainty uc(y)and the coverage factor k = 2. The interval from y − U to y + U is estimated to have a levelof confidence of approximately 95 %.

Water Program (Tritium in Precipitation, Tritium in Drinking Water)

• New York State Data – Long-Term Monitoring of Radioactivity in Surface Air andDeposition in New York State, Michael E. Kitto et. al., Health Physics, January 2006,Volume 90, Number 1, pages 31-37.

• Haddam Neck and Millstone REMP reports

2006 RETS-REMP Workshop, Ken Sejkora’s presentation on“Atmospheric Sources of Tritium and Potential Implications”

RADNET Precipitation (pCi/liter) 2001 – 2010

Region Range Avg. (overall avg. = 24.1)

• Region 1 0-809 38.3• Region 2 0-283 23.3• Region 3 0-2910 127 Wilmington DE 10/15/01

(1580) Lynchburg VA• Region 4 0-739 25.3• Region 5 0-608 29.1• Region 6 0-356 10• Region 7 0-361 20• Region 8 0-155 21.1• Region 9 0-583 8.2• Region10 0-1950 23.5 Olympia WA 11/15/01

(1720) Idaho Falls ID 10/15/05

RADNET Drinking Water (pCi/liter) 2001-2010

Region Range Avg. (overall avg. = 54.1)

• Region 1 0-933 26.3 Hartford CT 1/1/06• Region 2 0-1550 36.7 Syracuse NY 12/8/05• Region 3 0-3820 139 Ashland VA *• Region 4 0-1490 57.1 Charlotte NC et al*• Region 5 0-598 50.2 Liverpool OH 7/25/07• Region 6 0-548 15.2 New Orleans LA 8/30/07• Region 7 0-118 18.6• Region 8 0-158 27.3• Region 9 0-600 8.0 Honolulu HI 1/6/06• Region10 0-1400 21.6 Fairbanks AK 10/17/01

(734) Idaho Falls ID 1/17/06• * several positives

New York State Data 1982 - 2003

• H-3 Concentrations in atmospheric deposition

• Beginning in 2001, used lower-background detector tolower the detection limit

• Albany site – H-3 near or below the detection limit onall samples –range = 60 – 600 pCi/literaverage = 165 pCi/liter80 % of results: 55 to 65 pCi/liter (similar to elsewherein US

• Site near H-3 processing facility (facility closed in 1997)average = 8910 pCi/liter

Haddam Neck (Connecticut Yankee) REMP Data

• From mid 1970’s through approximately 1990,REMP vendor used hydrogen gas enrichmentfor low level H-3 counting of water samplesfrom Millstone and Haddam Neck (CY) – LLD(3 σ) typically 90 pCi/liter

• CY upstream river water sample resultstypically LLD for H-3 (i.e., below 90 pCi/liter!)

Results

• Yes, there is H-3 in precipitation, but:

• 10 year U. S. average is 24.1 pCi/liter

• Several outliers – not likely due to weaponsfallout – likely due to other manmadesource(s) – H-3 processing facilities, landfills,nuclear plants

• Weapons produced H-3 should be uniformlydistributed

Global Cycling Models for H-3• NUREG/CR 3332 Radiological Assessment, John E. Till, September 1983, page 9-13:

“In nature, tritium concentrations vary considerably, even in the equilibrium state,between numerous aqueous pools and geographical locations.”

• However, the equilibrium state is expected to be lower than that due to decaybecause of dilution in surface waters.

• Continental water balance, ground water inventory and storage times, surfacewater mixing rates and world-wide water circulation patters from cosmic-ray andbomb tritium, Friedrich Begemann and W.F. Libby, Geochimica et CosmochimicaAcata, Volume 12 , Issue 4, 1957, pages 277-296tritium produced during the Castle operation in the spring of 1954 was used tostudy the circulatory rates for waters in the northern hemisphere, partivulary inthe northern Mississippi valley“… about one-third of rain in upper Mississippi Valley is ocean water and abouttwo-thirds re-evaporated surface water.” …“ It has been found that on the average tritium has a residence of about 6 yearson the continentinal land mass of North America (radioactive decay taken intoaccount.”

7 compartment model

Figure Analysis

2006 RETS-REMP Workshop, Ken Sejkora’s presentation on“Atmospheric Sources of Tritium and Potential Implications”

“Real Background”

Cosmogenic: 3 – 15 pCi/liter

Weapons testing: 40 +/- 40 pCi/liter

Industrial sources: highly localizedlandfills (H-3 exit signs – NCRP 160 page 155 –

Pennsylvania landfills)production facilities (DOD, etc.)nuclear power plants

Know your H-3 Source Terms

Airborne Sampling Issues

• LLDs (NUREG 1301/1302)

• Grab sampling

• Bubbler

Airborne H-3 LLDs

H-3 Sampling Issues

H-3 Sampling Issues• NUREG 1301/1302 –

notation 4 – H-3 grab samples shall be taken at least once per 24 hourswhen the refueling canal (cavity??) is floodednotation 5: H-3 grab samples shall be taken at least once per 7 daysfrom the ventilation exhaust from the spent fuel pool area wheneverspent fuel is in the spent fuel pool – is monthly H-3 sampling onAuxiliary Building exhaust sufficient????

• Largest source of airborne releases – SFP (refueling cavity duringrefueling, fuel building during spent fuel transfers to ISFSI)Good practice is to track water added to pool and compare to airbornetritium measurements especially for sites relying on grab samplesRich Conatser made a presentation on how to calculate the waterevaporation several years ago, but if simple and easy to measure - whynot? And it better justifies the above deviation from the NUREGs

• Charcoal cartridges collect moisture – can cause a negative bias duringsampling

Condensation• OE33169 – Tritium Found is Standing Water at Low Level

Radwaste Storage Building (Arkansas Nuclear One)

• OE33426 – Atmospheric deposition causes elevated tritiumlevels in two monitoring wells (Callaway)

• OE33480 – Characterizing Tritium Release When Fuel StorageBuilding (FSB) Fans are Secured (Indian Point 3)

• AC condensate in yard area adjacent to Millstone Unit 2Auxiliary Building Roof Top Release – 40,000 pCi/liter in OilSeparator #5 (OS-5) - AC drain hose went directly to OS-5(Millstone 2)

• Tritium found on Millstone Unit 3 RWST pad (also foundationdrains sump and electrical manholes)

Millstone 3 RWST Area

Questions