epri radiation management program: review of radiation field reduction strategies

EPRI Radiation Management Program:Review of Radiation Field Reduction Strategies

ISOE Asian Technical Center ALARA SymposiumSeptember 8th, 2009

Dennis Hussey, Ph.D.Sr. Project Manager

Radiation Management, Chemistry, LLW, Fuel Reliability

2© 2009 Electric Power Research Institute, Inc. All rights reserved.

Overview

EPRI Support of RP2020

Boiling Water Reactor Highlights

• Elemental cobalt measurements

• BWR Shutdown Calculations

Pressurized Water Reactor Highlights

• Dose Rate Trends

Radiation Protection Technology Demonstrations


RP2020 Mission

Reshape radiological protection at nuclear power plants to achieve significant improvements in safety performance and cost-effectiveness.


Partners in CreatingRP 2020

NEI

EPRI INPO

NEI = PolicyINPO = PerformanceEPRI = Research

Radiation Protection Managers Chief Nuclear Officers


RP2020 Strategies and EPRI Status

• Reduce radiation fields—EPRI

• Improve technologies utilization—EPRI

• Standardize RP criteria & practices—ALL

• Redefine RP roles/responsibilities—NEI/INPO/EPRI

• Influence RP regulations—NEI


Source Term Reduction Program Strategy

• EPRI Source Term Reduction Program focuses on four areas

Data Collection/Analysis-Collect and organize available data(BWRVIP, SRMP, FRP, SGDD, Chemistry)-Blocking analysis

Theoretical Review-Materials Analysis-Chemistry/Operations Interactions-Transport Mechanisms

Operations Analysis-Shutdown benchmarking-Radiation data correlation-In-depth case studies

Technology Review-Investigate candidates-Evaluate promising candidates-Report results

Plant Specific Recommendations


Source Term Activation and Transport

Corrosion Product Sources

(tubing, valves, components)

59Co

58Ni

Fuel in Reactor

60Co

58Co

Ex-core Surfaces (piping, valves)

Water

Normal OperationsShutdown CleanupRefuel


Source Term Magnitude By LocationPWR Example

Location Surface Loading (uCi/cm2)

Total Curies

Fuel Co-58 = 250Co-60 = 12

~10,000-15,000 Ci Co-58~500-750 Ci Co-60

Removal During Shutdown

N/A 500-5000 Ci Co-585-50 Ci Co-60

Ex-core Surfaces (including tubing, piping, channel heads)

Co-58 = 8Co-60 = 3

~150-200 Ci Co-58~ 70 Ci Co-60


BWR Source Term Reduction Project

• BWR Source Term Reduction – Estimating Cobalt Transport to the Reactor (Report #1018371)

• Goals of Project

– Identify how plants measure cobalt

– Target cobalt sources

– Benchmark cobalt transport to reactor

– Quantify removal and releases during shutdown and normal operations


BRAC Measurement Points

B RECIRC PUMP A RECIRC PUMP

'A' RISER 30 o 'B' RISER 60 o

'C' RISER 90 o 'D' RISER 120 o

'E' RISER 150 o 'F' RISER 210 o

'G' RISER 240 o 'H' RISER 270 o

'J' RISER 300 o 'K' RISER 330 o

'B' SUCTION 0 o 'A' SUCTION

180 o

FCV 68 - 35 FCV

68 - 33

FCV 68 - 1

FCV 68 - 3 FCV

68 - 79 FCV 68 - 77

HCV 74 - 69

FCV 74 - 49

HCV 74 - 55

584' grating

563' grating

550' floor

C/L 556' - 8"

C/L 552' - 4"

C/L 580' - 9" 22' Discharge

Header

593' - 4" 591'11" WHIP RESTRAINT

591'11" WHIP RESTRAINT

N1B N2E N2D N2C N2B N2A N2K N2J N2H N2G N2F

1AD

5A

4A

3A

2A 1A

2AS

N1A

1BD

5B

4B

3B

2B 1B

2BS

XX OR XXX DENOTES SURVEY POINT, POINTS SHOULD BE MARKED ON MIRRO R INSULATION

B RECIRC PUMP A RECIRC PUMP

'A' RISER 30 o 'B' RISER 60 o

'C' RISER 90 o 'D' RISER 120 o

'E' RISER 150 o 'F' RISER 210 o

'G' RISER 240 o 'H' RISER 270 o

'J' RISER 300 o 'K' RISER 330 o

'B' SUCTION 0 o 'A' SUCTION

180 o

FCV 68 - 35 FCV

68 - 33

FCV 68 - 1

FCV 68 - 3 FCV

68 - 79 FCV 68 - 77

HCV 74 - 69

FCV 74 - 49

HCV 74 - 55

584' grating

563' grating

550' floor

C/L 556' - 8"

C/L 552' - 4"

C/L 580' - 9" 22' Discharge

Header

593' - 4" 591'11" WHIP RESTRAINT

591'11" WHIP RESTRAINT

N1B N2E N2D N2C N2B N2A N2K N2J N2H N2G N2F

1AD

5A

4A

3A

2A 1A

2AS

N1A

1BD

5B

4B

3B

2B 1B

2BS

XX OR XXX DENOTES SURVEY POINT, POINTS SHOULD BE MARKED ON MIRRO R INSULATION


BRAC Radiation Fields (June 2008)Mitigation Strategy


BWR Benchmarking/Source Term Ranking

Co-60 Categories and BRAC

Parameter Low Rxtor Water Co-60 Plants

(≤ 1E-4 µCi/ml)

Moderate Reactor Water Co-60 Plants

(>1E-4 µCi/ml, < 2E-4 µCi/ml)

High Reactor Water Co-60

Plants(≥ 2E-4 µCi/ml)

Average Co-60; µCi/ml

7.95E-5 1.38E-4 4.13E-4

Median Co-60; µCi/ml

6.48E-5 1.40E-4 2.79E-4

Co-60 Range; µCi/ml

1.94E-5 to 2.74E-4 5.98E-5 to 3.29E-4 9.42E-5 to 1.83E-3

Average BRAC; mR/hr

130 251 262

Median BRAC; mR/hr

89 261 168

BRAC Range; mR/hr

23-406 150-375 20-965


Impact of Control Rod Blade Replacement on Reactor Water Cobalt

0

1

2

3

4

5

6

7

8

9

No Stellite in Control Rod Blades

Replaced Stellite in >75% of CRBs

Replaced Stellite in >50% and <75% of

CRBs

Replaced Stellite in >25% and <50% of

CRBs

Num

ber o

f pla

nts

repo

rting

Low RW Co-60 (≤ 1E-4 µCi/ml)

Medium RW Co-60 (>1E-4 µCi/ml, < 2E-4 µCi/ml)

High RW Co-60 (≥ 2E-4 µCi/ml)

Joseph F. Giannelli

Is there a take-away statement from this slide?


BWR Summary and Recommendations

Recommendations

1. Plants should update cobalt source term reduction status (CRBs, turbine components, valves, etc.)

2. Conduct industry survey to see if plants have performed NP-2263 source identification evaluations

3. Conduct a further evaluation on elemental cobalt sampling with focus on sample collection, preparation and analytical methods


PWR Source Term ReductionTechnology Evaluations—Report 1016767

• Key Results

– Zinc continues to show significant radiation benefits

– pH effects noticed when comparing before and after PWR Primary Guidelines

• Ringhals, San Onofre report benefits of elevated pH

• Comanche Peak 1 and 2 do not show clear benefits

– Long term benefits of electropolishing are noted


Westinghouse SRMP Monitoring Points

Crossover piping and SG Hot leg piping Cold leg piping

Steam Generator Channel Head

Loop piping


SRMP: PWR Center Channel Head Hot Leg Most Recent Available Cycle

0

1

2

3

4

5

6

7

8

9

Avg

Hot

Leg

Cha

nnel

Hea

d D

ose

Rate

(R/h

r)

Plant ID


SRMP: PWR Loop Piping Cold Leg Most Recent Available Cycle

0

50

100

150

200

250

300

350

Aver

age

Cold

Leg

Dos

e Ra

te (m

R/hr

)

Plants

AvgCL Dose Rate (mR/hr)


Zinc Injection Impact on Radiation Fields

• Several examples of positive impact of zinc

• Diablo Canyon 1 is most striking

– Cobalt-60 decay curve is followed

– Implies no additional activity deposition

0

2

4

6

8

10

12

14

0.00 2.00 4.00 6.00

Surf

ace

Activ

ity o

f Co-

60 (u

Ci/c

m2)

Years since zinc implementation

Predicted Co-60 Surface Activity from Decay (uCi/cm2)Measured Co-60 Surface Activity (uCi/cm2)

For Diablo Canyon 1, since zinc injection, Cobalt-60 surface loading follows Co-60 decay curve at Diablo Canyon 1


Impacts of PWR Primary Chemistry Guidelines on Dose Rates


PWR Summary/Conclusions

• Zinc appears to be the strongest option to reduce ex-core dose rates

• pH has an impact, but mechanism is under investigation


RP 2020 Technology Program

• Support of RP2020 Initiative to Improve RP Technology Implementation

• Identify plant tasks for high individual and cumulative dose, use technologies to improve dose performance

• Multi-year project focusing task analysis, technology search and development for high individual dose tasks

• Outage reports collected, tasks separated

• Reduction of radiation fields allows planning of plant operations to minimize dose rates and reduce crud burst time

Objective:

Description:

Results to Date:

Benefits:


RP 2020 Technologies

• Project has strategic and tactical parallel paths

– Task Dose Benchmarking

– Technology Identification and Demonstrations


RP Technology Implementation Roadmap

Radiation Protection Technologies Project Roadmap

See

k U

tility

Im

plem

enta

tion

EP

RI a

nd

Ven

dor

Com

mun

icat

ion

Iden

tify

Tec

hnol

ogie

s

Dat

a A

cqui

sitio

n an

d O

rgan

izat

ion Acquire

dose reports (PADS, outage reports)

Identify high individual

dose tasks

Identify high cumulative dose tasks

MRP (e.g. Oconee

vessel inspections)

NDE(e.g. Weld

inspections)

SGMP(e.g. eddy

current inspections)

Maintenance (RRAC)

Vendors

Improved shielding

Communication improvements

Optimize time in field

Remote technologies

Identify a host site

Implement technology and report results


Technology Implementation ExampleIdentify the Task/Individuals

• Reactor Assembly/ Disassembly is a high dose task

– High dose rates

– Many tasks

• stud tensioners

• CRD work

– Shielding difficulties

• Preliminary results show high effective dose rates

– cumulative dose/work hours 0 50 100 150 200 250

Scaffolding

Rx Assembly & Disassembly

Mechanical Maintenance & valves

Modifications

Minor Maint in Steam Affected Areas

Refuel - Defuel

Drywell - Check Valve Repair

Rad Protection - Routine

CRD Changeout

Drywell Reactor Coolant System work

Shielding

Operations - Routine

PM - MOVs - VOTES

Drywell Under Vessel Activities

ISI - Erosion - Corrosion

Insulation

RP Plant Decon & cavity decon

SRV and ERV Work

mSv

Average Dose for 5 BWRs (mSv)

Avg


Technology Implementation Example Select Candidate Technology

• Real Time Location Sensors to assess efficiency– Reports 3-D position to

3 cm resolution

– Use it to • Determine work flow path

• Identify unnecessary personnel exposure

• Identify possible parallel tasks


Technology Implementation ExampleIdentify Host Site

• Determine plants that may be interested in demo during outage

– Communicated with two utilities

• Identify utility/vendor co-funding opportunities


RP 2020 Technology ImplementationPart II: Technology Demonstrations

• Utilities are already trying new technologies

• Technology list is in development

• For viable candidates, goal is to co-fund demonstration

Decontamination

Local system decontaminations

Control Rod Drive Flushing Tool

Cavity decontamination with peroxide

Dry vacuuming of vaults

Shielding

Shielding mats for refuel bridge

Permanent shielding on aux building systems

Moldable shieldingRemote Technologies

Remote welding and sanding

Remote monitoring (fiber penetration)

Wireless remote monitoring

Bluetooth communications technology

Novel Technologies

RadBall ™

Valve seat replacements

Replacement fiber insulation with reflective insulation

Location Tracking


RP 2020 Technology DemonstrationsAdvanced Shielding

• Customizable shielding for high dose applications

– E.g Nozzle inspection

• Engineering qualification for permanent installation

– Physical properties

• Hardness variation

• Linear weight

– Environment limitations

• Temperature

• Radiation

• Seeking utility support for installation


RP 2020 Technology DemonstrationsRadBall

• Radiation sensitive polymer based radiation mapping device

• Locate, quantify and characterize radiation


RP 2020 Technology DemonstrationsFrontline Headset-Camera

• Wireless and wearable communication tool that transmits video images

• On and off-site communication


Technology Conclusions

• EPRI is actively seeking new technology demonstrations

– International collaboration is welcome

– Please contact Dennis Hussey, [email protected]

epri radiation management program: review of radiation field reduction strategies

Documents

ci co

nuclear power plants

cimlmoderate reactor

source term magnitude

source term activation

benchmarkingsource term

reactor report

brac radiation fields