Summary Report of the EPRI Standard Radiation Monitoring Program

Dennis Hussey, EPRIAsian Technical Center ALARA SymposiumYuzawa, JapanOctober 11-13, 2006

2© 2006 Electric Power Research Institute, Inc. All rights reserved.

Overview

• History of Standard Radiation Monitoring Program (SRMP)

• Standard Radiation Monitoring Program Goals

• Plant Types and Survey Points

• Current Results

– US Responses

– Summary statistics of • loop piping

• channel head surveys

– Difference of cold leg and hot leg measurements

• Conclusions and Recommendations

3© 2006 Electric Power Research Institute, Inc. All rights reserved.

History of Standard Radiation Monitoring Program (SRMP)

• Started in 1978 to study radiation fields in Westinghouse-designed plants

– Program expanded to include Combustion Engineering (CE) designs

– In 1996, program was suspended because of a lack of industry interest and funding

• In 2003, NEI/INPO/EPRI developed the RP2020 Dose Reduction initiative

– Take Radiation Off the Table

– EPRI was charged to take the technical lead for source term reduction

– First goal was to benchmark PWR performance

4© 2006 Electric Power Research Institute, Inc. All rights reserved.

Standard Radiation Monitoring Program Goals

• Maintain the history of the program

– Much data have been acquired already

– Locations should not be change

• Make the procedure simple, focused, practical, and routine

– North American Technical Center recommendation

– Help HP staff so that HP staff can help us

• Organize the data to allow correlation to chemistry events and plant design

– PWR Monitoring and Assessment Database

• Encourage consistent sampling techniques

5© 2006 Electric Power Research Institute, Inc. All rights reserved.

SRMP Monitoring Points

• Workshop held in Charlotte March 7-9, 2006 to discuss– Selection of B&W points– Required vs Recommended points– Procedure clarifications

• Marker Discussions– Emergency Core Coolant System strainers limit

markers with vinyl– New markers made that are etched stainless steel

• Discussed further SRMP plans– Pre-oxidation points– Auxiliary system monitoring– Possible smears

6© 2006 Electric Power Research Institute, Inc. All rights reserved.

Westinghouse Monitoring Points

Crossover piping and SG Hot leg piping Cold leg piping

Steam Generator Channel Head

Loop piping

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Combustion Engineering Monitoring Points

Loop piping

Steam Generator Channel Head

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Babcock and Wilcox Monitoring Points

Loop piping

Steam Generator Channel Head

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Current US Survey Results

 Parameter/Plant Type W CE B&W Total

Plants 33/48 5/14 5/7 43/69

Total Number of Outages 982 275 180 1437

Loop Dose Rate Measurements 733 60 48 841

Channel Head Dose Rate Measurements

538 27 42 607

% Loop Measurements Received 74.6 21.8 26.7 58.5

% Channel Head Measurements Received

54.8 9.8 23.3 42.2

10© 2006 Electric Power Research Institute, Inc. All rights reserved.

Summary Statistics: Loop Piping—Hot Leg and Cold Leg

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

HotLeg

ColdLeg A

ColdLeg B

HotLeg

J-leg A J-LegB

HotLeg

ColdLeg

HotLeg

ColdLeg

CE B&W W 3 loops W 4 Loops

Plant Type/Loop Location

Do

se r

ate

(m

Sv/

hr)

Average (mSv/hr)Standard Deviation (mSv/hr)Max (mSv/hr)Min (mSv/hr)

11© 2006 Electric Power Research Institute, Inc. All rights reserved.

Summary Statistics: Channel Head Center

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

Point 2 Point 6 Point 2 Point 10 Point 2 Point 10 Point 2 Point 8

CE W 3 Loop W 4 Loop B&W

Plant Type/Location

Dos

e ra

te (

mS

v/hr

)

Average (mSv/hr)

Standard Deviation (mSv/hr)

Max (mSv/hr)

Min (mSv/hr)

12© 2006 Electric Power Research Institute, Inc. All rights reserved.

Summary Statistics: Channel Head, Cold Leg - Hot Leg Difference

-150

-100

-50

0

50

100

150

200

Pt10-Pt2 Pt10-Pt2 Pt6-Pt2 Pt8-Pt2

W 3 Loops W 4 Loops CE B&W

Plant Type/Points

Cha

nnel

Hea

d D

ose

Rat

e D

iffer

ence

(m

Sv/

hr)

Average (mSv/hr)Standard Deviation (mSv/hr)Max (mSv/hr)Min (mSv/hr)

13© 2006 Electric Power Research Institute, Inc. All rights reserved.

Conclusions

• The Standard Radiation Monitoring Program has been re-instated

• The procedures have been simplified for the HP staff

• Babcock and Wilcox plants are now included in the program

• The historical measurement points have been maintained for reference

• The data variability is quite large over time

– Westinghouse-designed plants have largest limits, and longest history

– Summary stats are not enough for a quantitative analysis of dose rates

• The trend of the cold leg having higher radiation fields than the hot leg has been confirmed for Westinghouse and CE plants

– Unexpected results obtained for the B&W plants

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Recommendations

• Analyze the data to evaluate the change in radiation fields over time

– Time-based data will help understand transient changes in radiation fields

– Effects of system changes will be observable

• Compare the plants by chemistry operations, steam generator materials, and core duty

– SRMP database is combined with the EPRI PWR Chemistry Monitoring and Assessment Database

– Combined database also includes• Steam generator information

• Limited core duty

15© 2006 Electric Power Research Institute, Inc. All rights reserved.

Acknowledgements

• EPRI Solutions

– Sam Choi, Cara Libby

• PWR ALARA Group

– Leonard Rollins, Dan Stoltz

• North American Technical Center

– David Miller, Scott Schofield

• Romain Bouchacourt