Transcript Powerpoint
Slide 1
A Method for Quantifying Noble
Gas Releases
Doug Wahl
Limerick Generating Station
Slide 2
Radiation Monitoring Display
System (RMDS)
• Design
– Continuous monitoring
gaseous effluents.
– Alert Operations to
abnormal releases.
– Quantify gaseous
effluents for reporting
and dose calculations.
– Sensitivity of 1E-06
uCi/cc (Xe-133) .
Slide 3
Effluent Monitoring History
• RMDS Computer System failed in 1997.
• System continued to function, but data was not
stored for more than a one-hour period.
– Live time available for emergency dose calculation.
– Data was over written with new data.
• No record of effluent releases.
• Relied on grab samples for quantifying effluent
releases.
• Reported 0 curies of Noble Gas released in 1997
and 1998.
Slide 4
Effluent Monitoring History
• New computer system installed in 1999.
• Received an NRC violation in 1999.
– Failure to maintain records of effluent releases - Tech.
Spec. violation.
• Inspector’s Philosophy
– Power plants are not zero release.
– Accuracy of numbers reported.
• Urged Limerick to develop a means to quantify
effluent monitor results.
Slide 5
New RMDS
• Drawback
– Electronic files not
available except by IT.
– Available as hard copy
printouts only.
– Don’t know when
normal releases are
occurring.
– No Trending of data
Slide 6
Method of Quantification
• Obtained the Weekly 1-hour Average
Radiation Effluent Monitor Data Printout.
• Determined the Daily High and Low 1-hour
Readings (uCi/cc).
• Averaged the Daily High and Daily Low to
Obtain Daily Average.
Slide 7
Method of Quantification
• Assigned the Lowest 1- hour Reading for
the Week as Background (uCi/cc).
• Subtracted the Background from each Daily
Average.
• Multiply by Flow and Time to obtain Curies
released for Week.
• In 1999 Reported 1412 Curies released.
Slide 8
Hourly Average Monitor Readings
for a 1-week Period
7.00E-07
NS - A
5.00E-07
4.00E-07
Value used as
Background for week
3.00E-07
Date/Time
3
09
/0
9/
0
3
09
/0
8/
0
3
09
/0
7/
0
3
09
/0
6/
0
3
09
/0
5/
0
3
09
/0
4/
0
3
09
/0
3/
0
3
09
/0
2/
0
3
09
/0
1/
0
3
2.00E-07
08
/3
1/
0
uCi/cc
6.00E-07
Slide 9
Consequences of Method
• More than 1400 Curies of Noble Gas Released Annually
from 1999 through 2002.
• Limerick is in INPO’s Worst Quartile for Gaseous
Releases.
• Gaseous Effluents is one of the Twelve Areas of Plant
Performance Measured by ANI’s Engineering Rating
Factor.
• Portion of Nuclear Plant’ Liability Premium is
Redistributed.
– Best performers – 20 percent credit
– Worst performers – 30 percent surcharge.
• Limerick Pays a Surcharge of about $40,000.
Slide 10
Airborne Fission and Activation Gaseous Effluents
Comparison by Year per BWR Reactor (Total Curies)
1.00E+06
WORST QUARTILE
MEDIAN
BEST QUARTILE
LIMERICK
1.00E+05
1.00E+04
723
1.00E+02
1.00E+01
1.00E+00
1.00E-01
Year
02
20
00
20
98
19
96
19
94
19
92
19
90
19
88
19
86
19
84
19
82
19
80
19
78
19
76
19
74
19
72
19
70
1.00E-02
19
Curies
1.00E+03
Slide 11
Why the ANI Surcharge?
• A Perceived Increase Risk of Litigation.
– ACE - Alliance for Clean Environment
• Tooth Fairy Project
• Limerick “Part of the Toxic Triangle”
Slide 12
2000 Effluent Survey
• 19 Plants Participated.
• 11 Assigned Zero Activity for the Month if
No Activity Found in Grab Sample.
• Survey Raised Several Questions?
Slide 13
2000 Effluent Survey
• Is it Appropriate to Rely on the Monthly NG Grab
Sample as the Station’s Sole Record of Release?
• If No NG Activity is Found in the Grab Sample,
Should you Report Zero Activity for the Month?
• Are INPO’s Rankings Comparing Apples to
Apples?
• What is Background?
Slide 14
Noble Gas Grab Sampling
• Monthly Requirement.
• Additional Sampling as Warranted.
– Increase Release Rate as Observed by Control
Room
• One Point in Time.
– It doesn’t tell you what happened yesterday
• Qualitative.
– Nuclides being seen by rad monitors.
Slide 15
Noble Gas Grab Sampling
• In 2003 No Activity was found in the
Monthly Grab Samples.
• Does that Mean there were No Releases for
the Year?
• If No Activity is Found – How to Quantify
Gaseous Effluents?
Slide 16
-F
e
-J
a
-J
a
n03
n03
14
b0
-M 3
ar
07 -03
-A
p
01 r-0
-M 3
a
25 y-0
-M 3
ay
18 -03
-J
un
12 -03
-J
u
05 l-0
-A 3
ug
29 -0
-A 3
u
22 g-0
-S 3
ep
16 -03
-O
c
09 t-0
-N 3
o
03 v-0
-D 3
e
27 c-0
-D 3
ec
-0
3
18
25
01
uCi/cc
North Stack – A/B Monitor
1.50E-06
1.30E-06
RE26075A-3
RE26075B-3
1.10E-06
9.00E-07
7.00E-07
5.00E-07
3.00E-07
1.00E-07
Date
Slide 17
North Stack 4/23/03
2.00E-06
A - Monitor
B - Monitor
1.60E-06
1.20E-06
8.00E-07
4.00E-07
4:
00
6:
00
8:
00
10
:0
0
12
:0
0
14
:0
0
16
:0
0
18
:0
0
20
:0
0
22
:0
0
00
2:
0:
00
0.00E+00
Slide 18
Goal
• Develop a Method to Better Estimate Noble
Gas Releases.
– Statistically Driven
– Determine a “Reasonable” Background
• Understand the Role of the Noble Gas Grab
Sample.
Slide 19
Limerick’s Revised Approach
• Obtain the 2003 RMDS 1-hour Average Data from
Information Technology.
• Plot the Data, Observe and Investigate Anomalous
Results.
• Obtain the 2003 RMDS 15-minute Average Data
for the Days that the Noble Gas Grab Sample was
taken; as well as, for Days that Appeared to Show
a Release from the 1-hour Data.
Slide 20
Limerick’s Revised Approach
• Background Arbitrarily Chosen from 15minute Data One Hour before the NG Grab
Sample and One Hour after.
– Assumed that if No Activity Found in Grab
Sample then Effluent Radiation Monitor
Reading was Background
– Provided 8 data points for Statistics
• Action taken for All Six Effluent Radiation
Monitors (2 per release point).
Slide 21
Limerick’s Revised Approach
• If 15-minute Data not Available or Suspect,
then data from the Previous Month was
used as Background.
• Likewise, if Positive Activity were found in
the NG Grab Sample, then Background
Based upon a Previous Month where No
Activity was Found.
Slide 22
Limerick’s Revised Approach
• Each Monitor’s Monthly Calculated Mean
and 2 Standard Deviations was used as
Background for the Month.
Slide 23
Monthly Background Values
Mean + 2 SD of 15-Minute Data
Month
Common
North Stack
A
Common
North Stack
B
Unit 1
South Stack
A
Unit 1
South Stack
B
Unit B
South Stack
A
Unit 2
South Stack
B
Jan
7.59E-07
6.54E-07
5.71E-07
6.83E-07
7.73E-07
5.44E-07
Feb
7.91E-07
5.34E-07
6.40E-07
8.11E-07
7.85E-07
3.44E-07
Mar
7.63E-07
5.65E-07
5.63E-07
6.85E-07
6.22E-07
4.99E-07
Apr
7.62E-07
6.40E-07
6.12E-07
1.05E-06
8.17E-07
4.05E-07
May
7.58E-07
5.08E-07
6.46E-07
8.57E-07
1.06E-06
3.53E-07
Jun
6.31E-07
5.77E-07
5.17E-07
8.47E-07
6.82E-07
4.88E-07
Jul
7.01E-07
5.08E-07
4.84E-07
1.32E-06
5.63E-07
3.30E-07
Aug
6.56E-07
4.42E-07
5.73E-07
7.12E-07
7.12E-07
3.38E-07
Sep
7.28E-07
4.97E-07
5.71E-07
9.34E-07
6.08E-07
4.57E-07
Oct
7.48E-07
5.71E-07
6.10E-07
6.49E-07
8.48E-07
4.12E-07
Nov
6.04E-07
4.73E-07
5.22E-07
6.49E-07
7.47E-07
3.48E-07
Dec
7.16E-07
4.73E-07
5.05E-07
5.77E-07
7.45E-07
4.88E-07
Slide 24
Limerick’s Revised Approach
• Each Monitors Background Number was
Subtracted off Each Valid Hourly Reading.
• Net Activity from the A and B Monitors
were Averaged to obtain the Net Activity in
uCi/cc.
– Net Activity below Zero was Classified as Zero
or “No Release”
Slide 25
Limerick’s Revised Approach
• For Each Hour of Positive Net Activity the
Number of Microcuries Released was
Determined by the Formula:
Ci / hr
Stack Volume ( cc )
* Ci / cc * 3600 sec / hr
604800 (sec)
Where:
Stack Volume (cc)
604800 (sec)
uCi/cc
3600
=
=
=
=
Total weekly stack volume
Number of seconds in a week
Net average hourly rate for the A and B monitor
conversion from seconds to hour
Slide 26
Limerick’s Revised Approach
• Nuclide Mix Reported in FSAR Used to Calculate
Dose
• Using this Method Limerick Reported in the 2003
Annual Effluent Release Report 4.26 Curies of
Noble Gas.
– Significantly lower than the 1447 Ci reported in 2002.
– Contribute to a Reduction in the ANI Surcharge
– From INPO’s Worst Quartile to Best Quartile
Slide 27
Airborne Fission and Activation Gaseous Effluents
Comparison by Year per BWR Reactor (Total Curies)
1.00E+06
WORST QUARTILE
MEDIAN
BEST QUARTILE
LIMERICK
1.00E+05
1.00E+04
723
1.00E+02
1.00E+01
2.13
1.00E+00
1.00E-01
Year
02
20
00
20
98
19
96
19
94
19
92
19
90
19
88
19
86
19
84
19
82
19
80
19
78
19
76
19
74
19
72
19
70
1.00E-02
19
Curies
1.00E+03
A Method for Quantifying Noble
Gas Releases
Doug Wahl
Limerick Generating Station
Slide 2
Radiation Monitoring Display
System (RMDS)
• Design
– Continuous monitoring
gaseous effluents.
– Alert Operations to
abnormal releases.
– Quantify gaseous
effluents for reporting
and dose calculations.
– Sensitivity of 1E-06
uCi/cc (Xe-133) .
Slide 3
Effluent Monitoring History
• RMDS Computer System failed in 1997.
• System continued to function, but data was not
stored for more than a one-hour period.
– Live time available for emergency dose calculation.
– Data was over written with new data.
• No record of effluent releases.
• Relied on grab samples for quantifying effluent
releases.
• Reported 0 curies of Noble Gas released in 1997
and 1998.
Slide 4
Effluent Monitoring History
• New computer system installed in 1999.
• Received an NRC violation in 1999.
– Failure to maintain records of effluent releases - Tech.
Spec. violation.
• Inspector’s Philosophy
– Power plants are not zero release.
– Accuracy of numbers reported.
• Urged Limerick to develop a means to quantify
effluent monitor results.
Slide 5
New RMDS
• Drawback
– Electronic files not
available except by IT.
– Available as hard copy
printouts only.
– Don’t know when
normal releases are
occurring.
– No Trending of data
Slide 6
Method of Quantification
• Obtained the Weekly 1-hour Average
Radiation Effluent Monitor Data Printout.
• Determined the Daily High and Low 1-hour
Readings (uCi/cc).
• Averaged the Daily High and Daily Low to
Obtain Daily Average.
Slide 7
Method of Quantification
• Assigned the Lowest 1- hour Reading for
the Week as Background (uCi/cc).
• Subtracted the Background from each Daily
Average.
• Multiply by Flow and Time to obtain Curies
released for Week.
• In 1999 Reported 1412 Curies released.
Slide 8
Hourly Average Monitor Readings
for a 1-week Period
7.00E-07
NS - A
5.00E-07
4.00E-07
Value used as
Background for week
3.00E-07
Date/Time
3
09
/0
9/
0
3
09
/0
8/
0
3
09
/0
7/
0
3
09
/0
6/
0
3
09
/0
5/
0
3
09
/0
4/
0
3
09
/0
3/
0
3
09
/0
2/
0
3
09
/0
1/
0
3
2.00E-07
08
/3
1/
0
uCi/cc
6.00E-07
Slide 9
Consequences of Method
• More than 1400 Curies of Noble Gas Released Annually
from 1999 through 2002.
• Limerick is in INPO’s Worst Quartile for Gaseous
Releases.
• Gaseous Effluents is one of the Twelve Areas of Plant
Performance Measured by ANI’s Engineering Rating
Factor.
• Portion of Nuclear Plant’ Liability Premium is
Redistributed.
– Best performers – 20 percent credit
– Worst performers – 30 percent surcharge.
• Limerick Pays a Surcharge of about $40,000.
Slide 10
Airborne Fission and Activation Gaseous Effluents
Comparison by Year per BWR Reactor (Total Curies)
1.00E+06
WORST QUARTILE
MEDIAN
BEST QUARTILE
LIMERICK
1.00E+05
1.00E+04
723
1.00E+02
1.00E+01
1.00E+00
1.00E-01
Year
02
20
00
20
98
19
96
19
94
19
92
19
90
19
88
19
86
19
84
19
82
19
80
19
78
19
76
19
74
19
72
19
70
1.00E-02
19
Curies
1.00E+03
Slide 11
Why the ANI Surcharge?
• A Perceived Increase Risk of Litigation.
– ACE - Alliance for Clean Environment
• Tooth Fairy Project
• Limerick “Part of the Toxic Triangle”
Slide 12
2000 Effluent Survey
• 19 Plants Participated.
• 11 Assigned Zero Activity for the Month if
No Activity Found in Grab Sample.
• Survey Raised Several Questions?
Slide 13
2000 Effluent Survey
• Is it Appropriate to Rely on the Monthly NG Grab
Sample as the Station’s Sole Record of Release?
• If No NG Activity is Found in the Grab Sample,
Should you Report Zero Activity for the Month?
• Are INPO’s Rankings Comparing Apples to
Apples?
• What is Background?
Slide 14
Noble Gas Grab Sampling
• Monthly Requirement.
• Additional Sampling as Warranted.
– Increase Release Rate as Observed by Control
Room
• One Point in Time.
– It doesn’t tell you what happened yesterday
• Qualitative.
– Nuclides being seen by rad monitors.
Slide 15
Noble Gas Grab Sampling
• In 2003 No Activity was found in the
Monthly Grab Samples.
• Does that Mean there were No Releases for
the Year?
• If No Activity is Found – How to Quantify
Gaseous Effluents?
Slide 16
-F
e
-J
a
-J
a
n03
n03
14
b0
-M 3
ar
07 -03
-A
p
01 r-0
-M 3
a
25 y-0
-M 3
ay
18 -03
-J
un
12 -03
-J
u
05 l-0
-A 3
ug
29 -0
-A 3
u
22 g-0
-S 3
ep
16 -03
-O
c
09 t-0
-N 3
o
03 v-0
-D 3
e
27 c-0
-D 3
ec
-0
3
18
25
01
uCi/cc
North Stack – A/B Monitor
1.50E-06
1.30E-06
RE26075A-3
RE26075B-3
1.10E-06
9.00E-07
7.00E-07
5.00E-07
3.00E-07
1.00E-07
Date
Slide 17
North Stack 4/23/03
2.00E-06
A - Monitor
B - Monitor
1.60E-06
1.20E-06
8.00E-07
4.00E-07
4:
00
6:
00
8:
00
10
:0
0
12
:0
0
14
:0
0
16
:0
0
18
:0
0
20
:0
0
22
:0
0
00
2:
0:
00
0.00E+00
Slide 18
Goal
• Develop a Method to Better Estimate Noble
Gas Releases.
– Statistically Driven
– Determine a “Reasonable” Background
• Understand the Role of the Noble Gas Grab
Sample.
Slide 19
Limerick’s Revised Approach
• Obtain the 2003 RMDS 1-hour Average Data from
Information Technology.
• Plot the Data, Observe and Investigate Anomalous
Results.
• Obtain the 2003 RMDS 15-minute Average Data
for the Days that the Noble Gas Grab Sample was
taken; as well as, for Days that Appeared to Show
a Release from the 1-hour Data.
Slide 20
Limerick’s Revised Approach
• Background Arbitrarily Chosen from 15minute Data One Hour before the NG Grab
Sample and One Hour after.
– Assumed that if No Activity Found in Grab
Sample then Effluent Radiation Monitor
Reading was Background
– Provided 8 data points for Statistics
• Action taken for All Six Effluent Radiation
Monitors (2 per release point).
Slide 21
Limerick’s Revised Approach
• If 15-minute Data not Available or Suspect,
then data from the Previous Month was
used as Background.
• Likewise, if Positive Activity were found in
the NG Grab Sample, then Background
Based upon a Previous Month where No
Activity was Found.
Slide 22
Limerick’s Revised Approach
• Each Monitor’s Monthly Calculated Mean
and 2 Standard Deviations was used as
Background for the Month.
Slide 23
Monthly Background Values
Mean + 2 SD of 15-Minute Data
Month
Common
North Stack
A
Common
North Stack
B
Unit 1
South Stack
A
Unit 1
South Stack
B
Unit B
South Stack
A
Unit 2
South Stack
B
Jan
7.59E-07
6.54E-07
5.71E-07
6.83E-07
7.73E-07
5.44E-07
Feb
7.91E-07
5.34E-07
6.40E-07
8.11E-07
7.85E-07
3.44E-07
Mar
7.63E-07
5.65E-07
5.63E-07
6.85E-07
6.22E-07
4.99E-07
Apr
7.62E-07
6.40E-07
6.12E-07
1.05E-06
8.17E-07
4.05E-07
May
7.58E-07
5.08E-07
6.46E-07
8.57E-07
1.06E-06
3.53E-07
Jun
6.31E-07
5.77E-07
5.17E-07
8.47E-07
6.82E-07
4.88E-07
Jul
7.01E-07
5.08E-07
4.84E-07
1.32E-06
5.63E-07
3.30E-07
Aug
6.56E-07
4.42E-07
5.73E-07
7.12E-07
7.12E-07
3.38E-07
Sep
7.28E-07
4.97E-07
5.71E-07
9.34E-07
6.08E-07
4.57E-07
Oct
7.48E-07
5.71E-07
6.10E-07
6.49E-07
8.48E-07
4.12E-07
Nov
6.04E-07
4.73E-07
5.22E-07
6.49E-07
7.47E-07
3.48E-07
Dec
7.16E-07
4.73E-07
5.05E-07
5.77E-07
7.45E-07
4.88E-07
Slide 24
Limerick’s Revised Approach
• Each Monitors Background Number was
Subtracted off Each Valid Hourly Reading.
• Net Activity from the A and B Monitors
were Averaged to obtain the Net Activity in
uCi/cc.
– Net Activity below Zero was Classified as Zero
or “No Release”
Slide 25
Limerick’s Revised Approach
• For Each Hour of Positive Net Activity the
Number of Microcuries Released was
Determined by the Formula:
Ci / hr
Stack Volume ( cc )
* Ci / cc * 3600 sec / hr
604800 (sec)
Where:
Stack Volume (cc)
604800 (sec)
uCi/cc
3600
=
=
=
=
Total weekly stack volume
Number of seconds in a week
Net average hourly rate for the A and B monitor
conversion from seconds to hour
Slide 26
Limerick’s Revised Approach
• Nuclide Mix Reported in FSAR Used to Calculate
Dose
• Using this Method Limerick Reported in the 2003
Annual Effluent Release Report 4.26 Curies of
Noble Gas.
– Significantly lower than the 1447 Ci reported in 2002.
– Contribute to a Reduction in the ANI Surcharge
– From INPO’s Worst Quartile to Best Quartile
Slide 27
Airborne Fission and Activation Gaseous Effluents
Comparison by Year per BWR Reactor (Total Curies)
1.00E+06
WORST QUARTILE
MEDIAN
BEST QUARTILE
LIMERICK
1.00E+05
1.00E+04
723
1.00E+02
1.00E+01
2.13
1.00E+00
1.00E-01
Year
02
20
00
20
98
19
96
19
94
19
92
19
90
19
88
19
86
19
84
19
82
19
80
19
78
19
76
19
74
19
72
19
70
1.00E-02
19
Curies
1.00E+03