TP-1

Decommissioning Overview and Decommissioning Overview and Alpha Contamination Hazards at Alpha Contamination Hazards at

Connecticut YankeeConnecticut YankeeNorth Carolina ChapterHealth Physics Society

February 22, 2007

Jay Tarzia, CHPRadiation Safety & Control Services, Inc.

TP-2

OutlineOutline• Connecticut Yankee History• Connecticut Yankee Decommissioning• Radiological Challenges Encountered

During Decommissioning• Identification and Control of Alpha

Source Term• Lessons Learned

TP-3

Connecticut YankeeConnecticut Yankee

TP-4

Connecticut Yankee HistoryConnecticut Yankee History• 582-Mwe Pressurized Water Reactor• Construction Period 1963 - 1967• Commercial Operation Jan 1, 1968• Permanently Shut Down December 4, 1996

TP-5

Shutdown DecisionShutdown Decision• Regulatory Issues Emerge - Fall 1996• Economic Evaluations Determine Continued

Operation Not in Consumer Interest• Shutdown Decision - December 4, 1996

TP-6

Regulatory Issues at Regulatory Issues at ShutdownShutdown

• Design Basis and Licensing Basis Deficiencies• Inadequate Corrective Action Program• Radiation Protection Events Emerging• Low Management Standards and Expectations• Procedure Deficiencies

Clear Indication From Regulator (NRC) That Issues Must Be Resolved Prior To Proceeding With Decommissioning

Resulting Fine May 1997 - $650,000

TP-7

Radiation Protection IssuesRadiation Protection Issues• November 1996 Fuel Transfer Canal Exposures

• Breakdown in Radiological Controls• Poor Work Planning, Control, Practices• Failure to Adhere to Fundamental

Radiological Safety• Inadequate Control of Radioactive Material

• Released Video Cables With Low Level Contamination\

• Radiation Monitoring System Inadequacies• Inadequate Calibration Procedures

Confirmatory Action Letter (CAL) Issued in May 1997 by NRC Limiting Work to ONLY Essential Radiological Work Until Program Improved

TP-8

RP Improvement ProgramRP Improvement Program• Administrative Controls Put in Place - Only

Essential Work

• Independent Assessment Performed

• Three Phase Improvement Plan Submitted to NRC

• Significant Regulator, Media and Public Interest

• Complete Overhaul of Program - 14 Month Effort

TP-9

Historical Site AssessmentHistorical Site Assessment• Identified several historical events leading

to onsite contamination• Spills and Leaks

• RWST• Airborne releases

• Stack Releases 1979• Radioactive system failures• Hazardous material used in

construction

TP-10

Offsite ContaminationOffsite Contamination• Historical Site Assessment Identified

the Potential Release of Concrete Shield Blocks to Employees (1975)

• Several Blocks Returned to Site -November 1997

• Over 5100 Blocks

• Contaminated Soil Also Identified

• Condition Not a Public Health or Safety Concern

• NRC Requires Any Detectable Licensed Material Be Recovered

TP-11

Offsite MaterialOffsite Material

TP-12

Offsite Material Recovery Offsite Material Recovery EffortEffort

• Over 140 Offsite Properties Evaluated

• Over 50 Properties Require Remediation

• Over 5,000 Blocks Located

• Significant Media and Public Interest

TP-13

Decommissioning 1997 Decommissioning 1997 • Resolution of Regulatory

Issues – NRC Confirmatory Action Letter (CAL) Issued

• Radiation Monitoring System Improvements and Recalibration

• Began Site Characterization and Historical Assessment

• Began Offsite Contamination and Recovery Efforts

INDICATES AREAS OF THE SITE THAT HAVE BEEN SURVEYED / SAMPLED FOR RADIOACTIVE MATERIALS - NO DETECTABLE ACTIVITY FOUND

INDICATES AREAS OF THE SITE THAT HAVE BEEN SURVEYED / SAMPLED FOR RADIOACTIVE MATERIALS - MEASURABLE ACTIVITY FOUND

INDICATES AREAS OF THE SITE THAT HAVE BEEN SURVEYED USING A SURFACE CONTAMINATION MONITOR

Revision #9 04/16/98

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PONDNo Detectable

Activity

COMMENTS: Areas Evaluated by Scanning, Soil Sampling and Exposure Rate Readings

CONNECTICUT RIVER

SCOPING SURVEY STATUS(1 OF 2)

TRAINING STORES OFF.

PRIMARYAUX. BUILDING

CONTROLROOM

INFORMATIONCENTER

POND

EMER GENCYOPERATIONS

CENTER

WASTEDISPOSAL

TK14- 1A

TK14- 1B

TK- 61 TK4-1 A

TK25- 1A TK

25-1B

SW ITCHGEARBLDG. "B"

TK- 33

FUEL OILTANK

TK- 20 TK- 62

TK- 171A&1B

TK- 63A&B

SPENT RESINSTORAGE

SPENT RESINFACILITY

CONTAINMENTACCESS BLDG.

REACTORCONTAINMENT

MOTO RCYCLEPARKING

PARKING LOT

OVER FLO WPARKIN G LOT

ROAD

RO AD

STEAM G ENERATORMOCKUP BUILDING

BOTTLED GAS STORAGEAREA

SHUT DO WNAUX FEED

PUMP HO USE

UNCON DITIONALRELEASEFACILIT Y

PENETRATION BUILD ING

RADWASTEREDUCTION

FACILITY

115KVSWITCH YARD

ISI &CONTRACTOR

SERVICES

TOOLISSUE

INSULATIONSHOP

FABSHOP

HYDROGENSTORAGE

ION EXCHANGESTR UCTURE

WAREH OUSE#2

WAREH OUSE WAREHOU SE

WAREHOUSE#1

SERVICE BUILDING

BOILERROOM

I&C / OPS

DIESEL

CYENG.

TURBINE BUILDING

ADMIN. BUILDING

MAINT.OFFICE

DISCHARGE CANAL

SEPTICSYSTEM

OFFICE BUILD.PAP

AUX. BAY

SECURITY OFFICE

X

STORM DRAIN DISCHARGE

Avg 15 mR/yr

Tree LineWooded Area

CENTRAL MOUNTAIN SIDE

.34mR/yr

BUS 10 Area

GPR Site STORM DRAINRUNOFF

Avg 11mR/yr

TP-14

Decommissioning 1998 Decommissioning 1998 • Completed

Resolution of Regulatory Issues – CAL Lifted

• Full System Decontamination

• BUS 10 Remediation

Group 1 Exposure Rates

0

200

400

600

800

1000

7/24 7/25 7/26 7/27 7/28 7/29 7/30 7/31 8/1 8/2

mR

/hr

TP-15

Decommissioning 1999 Decommissioning 1999 • Isolation of Spent

Fuel Island• Transition to a

Decommissioning Operations Contractor (DOC)

• Steam Generator and PressurizerRemoval

IntermediateCoolingPump

SprayCoolingPump

SprayCooler

SurgeTank

SurgeTank

Air,Vapor,Heat

Spray

SprayCooling

Loop

IntermediateCooling

Loop

Spen

t Fue

l Poo

l

Fuel

Spent FuelPool Cooling

Pump

SF Bldg. Roof

Spent FuelPool Cooling

Loop

Fan

Air

Makeup

Vent

RM

TP-16

Decommissioning 2000Decommissioning 2000• Reactor Coolant Pump and

Primary Piping Removal• Completion of “Cold and Dark”

Modifications• Asbestos Abatement• Reactor Vessel Internal (Core

Barrel) Segmentation• Transfer of GTCC • Submission of License

Termination Plan to NRC

TP-17

Decommissioning 2001Decommissioning 2001

• Reactor Head Segmentation and Disposal

• Cavity Recovery and Garnet Waste Transfer

• Primary Auxiliary Building (PAB) System Structure and Component (SSC) Removals

• Turbine Building System Removals

• Began FSS of Open Land Areas

TP-18

DecommissioningDecommissioning 20022002• Waste Disposal

Building (WDB) SSC Removal

• Independent Spent Fuel Storage Installation (ISFSI) Work Begins

• Begin Tank Farm SSC Removal

• Resolution of LTP RAIs

TP-19

DecommissioningDecommissioning 20032003• Reactor Cavity Drain

down• Reactor Cavity

Aggressive Decontamination

• Regenerative Heat Exchanger Removal

• Discharge Canal Dredging

• Reactor Vessel Removals

• Remediation of Landfill Area

• Termination of DOC

TP-20

DecommissioningDecommissioning 20042004• GTTC and Fuel

Moves• Containment

Commodity Removals

• Mirror Insulation Removal

• Neutron Shield Tank Removal

• Turbine Building Condenser Removal

• Begin Building Demolition

TP-21

DecommissioningDecommissioning 20052005• Internal Containment

Demolition• Spent Fuel Pool

Demolition• Underground

Commodity Removal

TP-22

DecommissioningDecommissioning 20062006• Containment Dome

Demolition• Discharge Canal

Restoration• Warehouse /

Outbuilding Demolition

TP-23

July 2003July 2003

TP-24

March 2005March 2005

TP-25

August 2005August 2005

TP-26

January 2007January 2007

TP-27

Radiological Challenges During Radiological Challenges During DecommissioningDecommissioning

• High Dose Rate Components and Systems

• Waste Classification and Packaging• Contaminated Soil and Groundwater• Significant Transuranic Source Term

• Potential for High Intakes• Release of Material Issues

TP-28

History of TRU Contamination at History of TRU Contamination at CYCY

• Operational Fuel Leakage• Significant in 1979 and

1989• Loss of Cavity Incident –

1984• Operational Tank and

Valve Leakage• Operational Spills• Chemical

Decontamination Events

TP-29

Regulatory and Stakeholder Regulatory and Stakeholder Interest in TRUInterest in TRU

• Heightened Sensitivity by NRC and Community Due to Past Plant Events• Transfer Canal Exposure Incident -

1996• Confirmatory Action Letter – 1997• Offsite Contamination Discovery –

1997• NRC Historical Site Review

TP-30

Typical Fission/Activation MixTypical Fission/Activation Mix• Large Variation• ETD Isotopes

• Co-60• Cs-137• Eu-

154/155/152• HTD Isotopes

• Most TRUs• Ni-63, Fe-55,

Sr-90

TP-31

Beta / Alpha RatiosBeta / Alpha Ratios• Containment

General Areas• 500/1 to 100 to 1

• PAB, WDB General Areas• 100/1 to 10 to 1

• RHR Pit, Pipe Trenches, Internal Systems• 50/1 to 1/1

• Most Plants • >10,000/1

TP-32

Alpha Contamination LevelsAlpha Contamination Levels

• Containment• Non-Detectable to 30,000 dpm / 100

cm2

• PAB, RHR Pit, Pipe Trenches• 200 to 100,000 dpm / 100 cm2

• Internal Systems• Up to 1,000,000 dpm / 100 cm2

TP-33

Airborne Radioactivity during Airborne Radioactivity during DecommissioningDecommissioning• Generated from:

• Work in Contaminated Areas• Dismantling Systems and

Components• Ratios Can Be Inconsistent and

Unpredictable• Usually Instantaneous or Short

Duration• Chronic Occupied Particulate Airborne

Levels are Rare

TP-34

Alpha Contamination Hazards Alpha Contamination Hazards During Decommissioning at CYDuring Decommissioning at CY

• Small Amount Lead to Very High Internal Doses• 13,200,000 dpm Co-60 = 1 rem• 2,640 dpm Am-241 = 1 rem

• Difficult to Detect in People • WBC does not detect Alpha

contamination• > 500 mrem Intakes Can be Missed by

WBC Due to Low Beta / Alpha Ratios• Detection Challenged by Radon

• Relatively High• Changes with weather, time, location.

Fecal Bioassays Assumed Inahlation Intake of .559 nCi, A

1E-04

1E-03

1E-02

1E-01

1E+00

0 2 4 6 8 10Time Post Intake, Days

nCi/d

ay

TP-35

Annual Limit on Intake, ALIAnnual Limit on Intake, ALI

• Listed in 10CFR20 for each Isotope for Inhalation or Ingestion

• Represents a Quantity of Radioactive Material, uCi.

• Results in Annual Dose Limit if Inhaled or Ingested For the Assumptions Used:

• Particle Size• Breathing Rates• Metabolism of “Reference Man”

• 1 ALI = 5 rem CEDE or 50 rem CDE

TP-36

Comparison of Alpha RisksComparison of Alpha RisksIsotope Half

LifeIngestionALI, uCi

InhalationALI, uCi

Np-237 2,140,000 y 0.5 .004Pu-238 88 y 0.9 .007Pu-239 24,131 y 0.8 .006Am-241 432 y 0.8 .006Rn-222 3.8 d None 10,000Rn-222

with daughters 3.8 d None 100Co-60 5.26 y 200 30Cs-137 30 y 100 200Mn-54 313 d 2000 800

Beta/Alpha Ratio for Co-60 & Am-241 = 30 ÷ 0.006 = 5,000

TP-37

Relative Internal Dose Potential For CoRelative Internal Dose Potential For Co--60 60 and Amand Am--241 Versus Beta: Alpha Ratio 241 Versus Beta: Alpha Ratio

1

10

100

1000

10 100 1000 10000 10000Beta to Alpha Ratio

TP-38

Internal Dose Assessment and Internal Dose Assessment and Control at CYControl at CY• Identification and Control of Potential

Internal Source Term Hazards• Characterization• Area Controls

• Identification of Potential Intakes• Follow-up Intake Assessments• Data Analysis and Assignment of Dose

TP-39

Identification of Potential IntakesIdentification of Potential Intakes

• Personnel Contaminations• Focus on Facial Area

• Positive Random WBC• Unexpected Positive

General Area Air Samples• CAM Alarms• Positive Lapel Air Sample

Results

TP-40

Area Controls for Area Controls for ““Alpha AreasAlpha Areas””at CYat CY

• Minimal Risk Areas:• < 200 dpm/100 cm2

• General RWPs

• Low Risk Areas• 200 – 1000 dpm/100 cm2

• Specific – 1 RWPs

• High Risk Areas• >1000 dpm/100 cm2 or Beta/Alpha

Ratios < 50/1• Specific – 2 RWPs

TP-41

Internal Dose Protection Internal Dose Protection MeasuresMeasures

• Minimize Sources• Use engineering

controls• Ventilation• Water

• Protective Clothing• Respirators

TP-42

Internal Hazard MonitoringInternal Hazard Monitoring• Contamination Levels

• Ingestion hazard• May Be A Source for

Airborne• Do Good Surveys!

• Airborne Radioactivity Levels• Inhalation hazard• Do Good Air sampling!

• General Area• Personal

TP-43

Relative Internal Dose Potential For CoRelative Internal Dose Potential For Co--60 60 and Amand Am--241 Versus Beta: Alpha Ratio 241 Versus Beta: Alpha Ratio

1

10

100

1000

10 100 1000 10000 1000Beta to Alpha Ratio

TP-44

Alpha Contamination Alpha Contamination MonitoringMonitoring

• Low MDAs Required for release• Fixed Contamination: 100 dpm/100

sq cm• Removable Contamination: 20

dpm/100 sq cm

• “Low” plant contamination levels can lead to high airborne activity levels depending on ratios.

TP-45

Alpha Airborne MonitoringAlpha Airborne Monitoring

• Critical to assess intakes (or lack of)• Radon Interference causes

challenges• Other monitoring concerns

• Depth of burial• cross contamination

TP-46

General Area Air SamplesGeneral Area Air Samples

• Used to assess peak values• Used to determine posting

requirements• May not be representative

enough for personnel intake assessment

TP-47

Personal (Lapel) Air SamplingPersonal (Lapel) Air Sampling

• Key Part of Program• Used as an Indicator for

Potential Intakes• True Breathing Zone

Samplers• Not good for measuring

DAC for posting• Great for measuring

“INTAKE”• Can be used as

“INTAKE DOSIMETERS”

TP-48

Lapel Air Sampler Intake Lapel Air Sampler Intake AssessmentAssessment• Reference Man breaths 1200 lph

(working)• Lapel Air Sampler flow rate = 2 lpm =

120 lph• Ratio of Reference Man to Lapel =

10:1• The INTAKE of the worker = 10 *

Lapel Activity

TP-49

CY Internal Dosimetry CY Internal Dosimetry ProgramProgram• Lapel Air Sampling• G/A Air Sampling• WBC Initiation Events• WBC Action Levels• In-Vitro Sampling

• Initiation for Urine and Fecal Sampling• Process Flow for Information Flow

• Random Bioassay Selection• Internal Dosimetry Assessment Process

TP-50

Lessons LearnedLessons Learned

TP-51

Events Leading to Significant Events Leading to Significant Alpha ContaminationAlpha Contamination

• Extended Operations with Significant Fuel Leakage

• Operational Spills• Long-term Valve and Component

Leakage

TP-52

Prevention of LongPrevention of Long--Term Alpha Term Alpha EffectsEffects

• Aggressive Cleanup and Documentation of Spills• 10CFR50.75g file

• Good Component Maintenance• Limitations and Evaluations of

Operating when Fuel Leakage is Detected

• Aggressive Routine Plant Decontamination

TP-53

Benefits of Using Lapel Air Benefits of Using Lapel Air SamplersSamplers

• More Representative than General Area Samples

• Excellent Sensitivity to Alpha Intakes• Rapid Indication of Potential Intakes

• Generally Conservative for Inhalation Intakes• Easy to Use

• No need to track on/off times• No need to calculate air volume• Just know who it belongs to and don’t lose it!

• Provides “Negative” Documentation• Worker and Public Trust

TP-54

The EndThe EndQuestions?