ALARA Performance at
OPG
Scott Cameron
Manager Radiation Protection
2008 International ALARA Symposium
Overview
1.
Introduction
2.
Dose Reduction Initiatives
3.
Human Performance
Improvements
4.
Future Challenges
Dose Reduction Initiatives:
Darlington
Installation of Submicron Filtration
20
80
15
60
Sub-micron
Filtration
10
5
52000
40
91000
26000
62000
11000
0
20
Outage Dose Savings (rem)
Dose Rate (mrem/h)
Unit 1 Containment Gamma Fields
0
2000
2002
Exposure-hour
2004
2006
Dose Savings
2008
Dose Rate
 HTS bleed filter pore size reduced in steps from 2 uM to 0.45 uM in
May/2002 and 0.1 uM in Dec/2003
 Increased filter replacement rate was driven by dose rate not ΔP
 Contribution to dose savings: 130 rem for Unit 1 since 2004
Dose Reduction Initiatives:
Remote Monitoring
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
• Teledosimetry for dose
monitoring and Rx face scan
A
B
C
D
E
F
G
H
J
K
L
M
N
O
P
Q
R
S
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U
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X
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100 117 118 100
124
65
61
59
54
48
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50
74
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84
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58
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80
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88
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100
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96
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68
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102
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104 100 110
68
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81
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72
89
91
86
79
80
69
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78
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62
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62
65
74
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49
78
74
65
68
63
63
67
60
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51
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58
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58
70
66
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74
84
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48
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51
60
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63
57
24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
Remote readout of gamma and
tritium levels at airlock (HP)
A
B
C
D
E
F
G
H
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Dose Reduction Initiatives:
Shielding Applications
•
Water wall for on-power
Airlock EQ work – 3 rem
dose and 4 M$ outage critical
path savings
•
Water bag for ECI hot spot
shielding
•
Face shielding
Rx Shield Block Data:
Each block weighs 22 lbs with a 7” hole
cut out
15 min and 14 mrem to install 35 blocks
Shielding effectiveness: Before shielding –
90 mrem/h, after shielding – 42 mrem/h
Dose Reduction Initiatives:
Decontamination
Application of strippable
Decon Gel
Example:
HX1 room floor Coated
and peeled the next day
• Before – 5000 cpm
• After - 0 cpm
• Peeling - 4.5 mrem/h C
Internal Dose Reduction:
Outage Tritium Reduction ALARA Plan




Action Levels established with pre-determined corrective actions
Reduce closure plug leakage (CP tightening, PHT low level drain
state to reduce static pressure)
Install portable dryers (96% capacity factor, 24 drums of D2O, 1200
Ci extracted from vault air)
Contain and reduce tritium @ airlocks (H3 <0.1 MPCa outside AL)
Munter
Dryer
Cooling Coil
1000-2000 MPCa
200 CFM
2-5 ℓ/h
166oC
45 Gal
Air Cooled
Condensing Unit
Electric
Heater
Outlet
E
Comp
F
F
2250 CFM
Fan
0.88 MPCa
36 MPCa*
DP = -56oC
DP = -20oC
Inlet
Desiccant
Rotor
* 9.06E-4 kg/m
3
x 6.5E5 µCi/kg x 0.61 x 1 MPCa/10 µCi/m3 = 36 MPCa
Human Performance Improvement:
Impact of Worker Practice
Human performance has a large impact on the effectiveness of RPPE:
• Good RP practice can increase protection factor (PF) by a factor of 2
• Human performance can be improved by communication and focused O&C’s
Tritium Protection Factor
200
150
100
50
1st wave of intense
communication
0
D431
D521
D541
D631
Outage
D611
D741
D731
Human Performance Improvement:
Example of Worker Communication Campaign
Communication campaign to emphasize impact of
unplugged time on tritium uptake:
 Video presentation and posters
 Outage handbook
 Safety meetings
Human Performance Improvement:
Coaching, Monitoring & Follow-up
Daily dose monitoring and follow-up of EPD dose and tritium uptake
Action levels:
 3 uCi/l or 10 mrem EPD – follow-up with worker/supervisor
 10 uCi/l above planned or EPD alarm – department EFDR, SCR
 35 uCi/l above planned or 100 mrem above EPD alarm – root cause
investigation
Performance management
 Focused observation and coaching (O&C) by RP staff
 Interview by RPM and RHP for significant events or repeats
 RP qualification review of worker and supervisor
Results of Tritium Reduction
Unpalnned Tritium Uptakes
( Tritium >= 10µCi/L)
90
80
Number of Events
70
60
50
Tritium >= 10µCi/L
40
30
20
10
0
2004
2005
2006
Year
? 22
2007
2008
ALARA Achievement
Three Consecutive WANO Strengths in
ALARA 2007, 2008 WANO:
• High standards in RP have been set and achieved
• Robust controls prevent unplanned exposures
• Extensive ALARA planning, innovative shielding and aggressive tritium
reduction
• Reactor face shielding
• On-line tritium / gamma system
Future Challenges:
2. Reduce γ dose rate in HT system by 25% by 2011
Gamma scans identify Co-60 as the dominant source of radiation
More than 80% of Co-60 originates from FM stellite ram balls
Long term plan: COG joint/R&D project to develop replacement
Short term plan: FM filtration improvement – submicron filters & IX
Containment Dose Rate Trend
30
17.5
mrem/h
25
13
mrem/h
20
15
Sub-micron
Filtration
10
Year
12
20
11
20
10
20
09
20
07
20
06
20
05
20
04
20
03
20
02
20
01
20
00
0
20
5
08
FM Submicron
Filtration
FM IX
Column
20
Dose Rate (mrem/h)
•
•
•
•