Transcript Electrical Cable Aging: What does IEEE Std. 1205

Module 5
Electrical Cable Aging:
What does IEEE Std. 1205-2000
Recommend?
Dr. John H. Bickel
Evergreen Safety & Reliability Technologies, LLC
Objectives
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Describe origins of IEEE Std.1205-2000
Describe requirements of standard regarding
electrical cables
Describe results of recent application in the US
NOTE: Standard covers all electrical components.
Emphasis will be on “difficult to replace”
electrical cables for which justification to use asis will be sought.
Origin of IEEE Std 1205-2000
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Many US NPP licenses expiring in next 10 years.
N.R.C. issued License Renewal regulation
permitting life extension subject to demonstration of
acceptable safety
Previous IEEE Std 1205-1993 standard felt to be
too “open ended” in considering “all possible aging
mechanisms”.
Question: “How much is enough?”
IEEE standard developed as industry – regulator
consensus on acceptable aging management
program to demonstrate acceptable safety for
electrical equipment.
Basis of New IEEE Std 1205-2000
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Major NPP systems, components have been
continually refurbished or replaced over their
lifetimes.
- Steam Generators, RPV head
- Turbine rotors
- Pumps, motors, valves
- I&C systems, plant computers
Original power (and portions of I&C) cable not
typically replaced for other reasons.
Incorporation of new materials aging data
It is desired to demonstrate safety basis for
acceptability of existing cabling and connectors.
Objectives of IEEE Std 1205-2000
Standard deals with all types of electrical
equipment.
 EQ standards (IEEE Std 323-1983) deal with
thermal, radiation pre-aging for purposes of
conducting DBA qualification tests.
 IEEE Std 1205-2000 credits that equipment
typically operates for long periods at below
pre-aging temperature, radiation levels.
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IEEE Std.1205-2000 Process:
IEEE Std.1205-2000 Process:
Aging Assessment Process
1. Define Evaluation Boundaries
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What is being evaluated?
What support features are included?
What are system interfaces?
What are system boundaries with interfacing
systems?
Why this is done:
To demonstrate at end of job that all systems
covered, no duplications, but also no omissions
2. Identify Intended Safety Function
What safety function does system provide
for DBA?
 What other safety functions is system
credited for?
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Why this is done:
Frequently systems are credited for different
roles in different scenarios.
3. Identify Plant Locations
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Identify specific rooms or zones of
equipment.
Why this is done:
Routing of support features such as signal
and power cables needed for determining
most limiting rooms or zones.
4. Identify Service Conditions
What are environmental conditions in each
of the rooms or zones?
 Temperature, radiation, moisture…..
 Which rooms or zones are most limiting?
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Why this is done:
Identifies locations of likely greatest
stressors for aging-related degradation.
5. Identify Equipment Materials
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What types of materials for this system are
located in each room or zone?
Which materials in the system are most limiting?
Why this is done:
A system may have both Power and
Instrumentation cables in the same zone.
Instrumentation cables may be more limiting.
6. Identify and Assess Aging Effects
What aging effects are possible for given
materials and environmental stresses?
 Which aging effect is most limiting?
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Why this is done:
Identification of conditions to be monitored,
bases for future calculations
Thermal and Radiation
Aging Models
Thermal and Radiation Aging Models
IEEE Std 1205-2000 starts with standard
aging models based Arrhenius type aging
and radiation damage type aging.
 Allows credit for actual operating
experience which may show significantly
reduced aging rates.
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Consideration of Operating Experience
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Cabling in areas of highest temperature and
radiation levels is typically limiting.
Typical EQ efforts conservatively assume, 40
years at 100% capacity factor.
High capacity factors imply higher radiation
doses and exposure to highest temperatures.
Actual operation may be less limiting and should
be taken into consideration in projecting residual
cable lifetime.
Projecting Residual Cable Lifetime
Based on Operating Experience
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Based on actual operating history conservative
“envelope” on temperature or radiation can be
constructed.
“Envelope” is conservative but also more
realistic.
Construction of Effective Time at
Temperature
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Desire is to construct
effective temperature
Teff for residual life
calculations.
Assume total time ttot
Condition Monitoring
Condition Monitoring
Observation, measurement, trending of
condition indicators with respect to critical
parameter known to cause degradation.
 Example parameters:
cumulative radiation dose
cumulative time at effective temperature
 Monitor: degradation vs. radiation dose
 Monitor: degradation vs. time at Teff
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Acceptable Condition Monitoring
Acceptable Condition Monitoring
Some Results from Applying
IEEE Std 1205-2000
What is Max Teff for 60 Years ?
Calvert Cliffs SER Findings:
3.12.3.1 Effects of Aging
“The cable insulation material types include silicone rubber, ethylene
propylene rubber (EPR), crosslinked polyethylene (XLPE), crosslinked
polyolefin (XLPO), mineral, Kapton, polyvinyl chloride, Teflon, and
other miscellaneous insulation types.
The external environment is air. The applicant identified the applicable
ARDMs as thermal aging, synergistic thermal and radiative aging, and
insulation resistence reduction.
Although the license renewal rule requires management of aging effects
and does not require specific identification of ARDMs, the applicant
elected to evaluate specific ARDMs. The applicant considered a
comprehensive list of potential ARDMs in its evaluation.
The staff finds this acceptable because the potential ARDMs of
thermal/radiative aging, and insulation resistence reduction are
considered to be plausible for cables. Accordingly, the staff finds the
applicant's approach of identifying ARDMs acceptable because aging
effects are results of ARDMs.”
Calvert Cliffs SER Findings:
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The operating experience information in the application indicates
that the number of cable failures during normal operating conditions
(all voltage classes) that have occurred throughout the industry have
been extremely low. However, thermal aging resulting in
embrittlement of insulation is one of the most significant aging
mechanisms for low-voltage cable during normal operating
conditions.
Calvert Cliffs SER Findings:
3.12.3.2.2 Effects of Synergistic Thermal and Radiative Aging
“Group 3 cables may be subjected to synergistic radiative and thermal
aging when both aging mechanisms are active and at least one may
be significant.
Radiation-induced and thermal-induced degradation in organic
materials (cable jacket and insulation) produces changes in the
organic material properties, including reduced elongation and
changes in tensile strength.
Visible indications of radiative/thermal aging may include embrittlement,
cracking, discoloration, and swelling of the jacket and insulation.
To manage the aging effects on Group 3 cables, they will be replaced
before the extended period of operation if they are found to have
plausible aging.”
IEEE Std 1205-2000 Process
Aging Management Process has proven to
be:
 Orderly
 Repeatable
 for both NPP operators making license
extension applications and for NRC in
reviewing and approving.
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License Renewal Status in US:
License Extensions Approved:
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Calvert Cliffs, Units 1 and 2
Oconee Nuclear Station, Units 1, 2
and 3
Arkansas Nuclear One, Unit 1
Edwin I. Hatch Nuclear Plant, Units 1
and 2
Turkey Point Nuclear Plant, Units 3
and 4
North Anna, Units 1 and 2, and Surry,
Units 1 and 2
Peach Bottom, Units 2 and 3
St. Lucie, Units 1 and 2
Fort Calhoun Station, Unit 1
License Extensions Pending:
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McGuire, Units 1 and 2, and Catawba,
Units 1 and 2 - Joint application
received June 14, 2001
H.B. Robinson Nuclear Plant, Unit 2 Application received June 17, 2002
R.E. Ginna Nuclear Power Plant, Unit
1 - Application received August 1, 2002
V.C. Summer Nuclear Station, Unit 1 Application received August 6, 2002
Dresden, Units 2 and 3, and Quad
Cities, Units 1 and 2 - Application
received January 3, 2003.
Farley, Units 1 and 2 - Application
received September 15, 2003.
Arkansas Nuclear One, Unit 2 Application received October 15, 2003.
D.C. Cook, Units 1 and 2 - Application
received November 3, 2003