ML11349A078
| ML11349A078 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 12/15/2011 |
| From: | Bascom E State of NY, Office of the Attorney General |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| References | |
| RAS 21545, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01, NYS000136 | |
| Download: ML11349A078 (36) | |
Text
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 1
UNITED STATES 1
NUCLEAR REGULATORY COMMISSION 2
BEFORE THE ATOMIC SAFETY AND LICENSING BOARD 3
x 4
In re:
Docket Nos. 50-247-LR; 50-286-LR 5
License Renewal Application Submitted by ASLBP No. 07-858-03-LR-BD01 6
Entergy Nuclear Indian Point 2, LLC, DPR-26, DPR-64 7
Entergy Nuclear Indian Point 3, LLC, and 8
Entergy Nuclear Operations, Inc.
December 14, 2011 9
x 10 PREFILED WRITTEN TESTIMONY OF 11 Earle C. Bascom III 12 REGARDING CONTENTIONS NYS-6 and 7 13 On behalf of the State of New York (NYS or the State),
14 the Office of the New York State Attorney General hereby submits 15 the following testimony by Earle Bascom regarding Contentions 16 NYS-6 and 7.
17 Q.
Please state your full name.
18 A.
Earle Clarke Bascom,III 19 Q.
By whom are you employed and what is your position?
20 A.
I am employed by Electrical Consulting Engineers, P.C.
21
("ECE"), a company I founded in 2010. I am the president and a 22 principal engineer.
23 NYS000136 Submitted: December 15, 2011
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 2
Q.
What kind of consulting does ECE do?
1 A.
Electrical Consulting Engineers, P.C. (ECE) provides 2
engineering consulting services to the electric power industry 3
and focuses on underground transmission and distribution cable 4
systems. Our work includes engineering design and analysis for 5
new cable circuits, rating capacity studies, and cable system 6
assessments on existing cable systems. Most of our work is 7
performed for utilities, though occasionally we work as 8
subcontractors for architect-engineering firms that lack 9
expertise in underground cables.
10 Q.
Please summarize your educational and professional 11 qualifications.
12 A.
I hold an Associates of Science degree in Engineering 13 Science from Hudson Valley Community College, a Bachelors of 14 Science and Masters of Engineering degrees in Electric Power 15 Engineering from Rensselaer Polytechnic Institute, and an MBA 16 degree from the State University of New York at Albany.
17 Q.
Please summarize your employment before you founded 18 ECE in 2010.
19 A.
Prior to founding ECE, I worked for nine years with 20 Power Technologies, Inc (PTI, now part of Siemens) focusing on 21 underground cable systems within the Transmission & Distribution 22 Department. At the time I was employed there, PTI provided 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 3
transmission and distribution engineering consulting services 1
for overhead, underground, substation and generation equipment 2
as well as being a supplier of power system analysis (load flow, 3
etc.) software. In 1999, I left PTI and joined Power Delivery 4
Consultants, Inc. (PDC); PDC was focused on providing 5
engineering consulting services for underground transmission and 6
distribution systems, but also offered limited services for 7
overhead line and power transformer ratings. I was with PDC for 8
eleven years.
9 Q.
What is the purpose of your testimony?
10 A.
I was retained by New York State to review Entergy's 11 discussion in its License Renewal Application of the aging 12 management of non-environmentally qualified inaccessible low and 13 medium voltage power cables at Entergy's Indian Point nuclear 14 generating units 2 and 3 that are exposed to adverse localized 15 environments, and to assess whether Entergy has demonstrated 16 that it will adequately manage the effects of aging on those 17 cables so that the cables will perform their intended function 18 during the license renewal period.
19 Q. Have you reviewed materials in preparation for your 20 testimony?
21 A. Yes.
22 Q. What is the source of those materials?
23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 4
A. Many are documents prepared by government agencies, 1
or documents prepared by Entergy or by the Electric Power 2
Research Institute ("EPRI"), the research arm of the utility 3
industry.
4 Q. I show you NYS Exhibits 000139 through 000145. Do you 5
recognize these documents?
6 A. Yes. These are true and accurate copies of the 7
documents that I referred to, used and/or relied upon in 8
preparing my report and this testimony. In some cases, where 9
the document was extremely long and only a small portion is 10 relevant to my testimony, an excerpt of the document is 11 provided. If it is only an excerpt, that is noted on the first 12 page of the Exhibit.
13 Q. How do these documents relate to the work that you do 14 as an expert in forming opinions such as those contained in this 15 testimony?
16 A. These documents represent the type of information that 17 persons within my field of expertise reasonably rely upon in 18 forming opinions of the type offered in this testimony.
19 Q.
I show you what has been marked as Exhibit NYS000138.
20 Do you recognize that document?
21
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 5
A.
Yes. It is a copy of the report that I prepared for 1
the State of New York in this proceeding. The report reflects 2
my analysis and opinions.
3 Q.
Please give a brief summary of your testimony.
4 A.
Entergy has not demonstrated that it will manage the 5
effects of aging on non-environmentally qualified ("non-EQ")
6 inaccessible low and medium voltage cables exposed to 7
significant moisture because its License Renewal Application 8
lacks any substantive detail. Entergy does not specify the 9
location or number of the relevant cables, does not identify 10 their function or the criticality of the systems they serve, 11 does not describe their physical characteristics, does not 12 explain what corrective actions it will take if manhole 13 inspections reveal periodic water accumulation, does not explain 14 what cable condition monitoring tests it will use, does not 15 explain the criteria for determining whether a cable passes or 16 fails a condition monitoring test, and does not identify what 17 corrective actions, if any, Entergy will take if a defective 18 cable is found. Without this essential detail, Entergy has not 19 demonstrated that its Aging Management Plan will insure the 20 continued integrity and function of the non-EQ inaccessible 21 cables that are exposed to significant moisture during the 22 period of extended operation.
23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 6
In addition, Entergy has not provided any plan to manage 1
the effects of aging on non-EQ inaccessible low and medium 2
voltage power cables that are exposed to other localized adverse 3
environmental conditions, such as excessive heat. Also, Entergy 4
has not demonstrated that such a plan is unnecessary because 5
there are no non-EQ inaccessible power cables exposed to 6
excessive heat. Cable insulation exposed to excessive heat may 7
degrade faster than cable insulation exposed to significant 8
moisture.
9 Q.
What does the term non-environmentally qualified mean 10 in the context of these cables?
11 A. A cable is non-environmentally qualified if it is not 12 designed to withstand the adverse effects of the environment in 13 which it is located.
14 Q.
In the context of IP2 and IP3, in what way are the 15 non-EQ low and medium voltage cables inaccessible?
16 A.
In this context, inaccessible cables are either 17 directly buried underground or pulled through a buried conduit.
18 Q.
I would like to ask you some very basic questions 19 about electric circuits. First, what is an electric current?
20 A.
An electric current is a flow of electrons through a 21 conductor. A conductor is generally a wire made of copper or 22 aluminum -- materials that offer low resistance to the electron 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 7
flow. In order for an electric current to perform work, the 1
conductor must be part of a circuit through which the current 2
continuously flows.
3 Q.
What causes electrons to flow through a conductor?
4 A.
In alternative current systems, voltage produced by an 5
electric generator produces the force (electro-motive force) to 6
move the electrons through the conductor and around an electric 7
circuit. That force is measured in volts and is described as 8
voltage. Electric current is measured in amperes. Electric 9
power, or the work electricity can do, is the product of amperes 10 and voltage and is expressed as watts.
11 Q.
What are the basic components of an underground 12 electric cable?
13 A.
There are two basic components - the conductor that 14 carries the current and the cable insulation that prevents the 15 electricity in the conductor from discharging into the 16 surroundings. Other components of the cable help assure that 17 these two basic functions are maintained. If insulation is no 18 longer capable of preventing the electricity from discharging 19 into the surroundings, the voltage of the electricity drops, the 20 electricity faults to ground, the cable circuit fails and the 21 circuit is then unable to perform its task. In an electric 22 cable, the voltage between the conductor and the outer cable 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 8
layers is called "line to ground voltage." It represents the 1
electrical potential on the conductor to drive the movement of 2
the electrons 3
Q.
Please define the terms "low voltage cable" and 4
"medium voltage cable."
5 A.
Low voltage cable generally refers to cables that are 6
classified for operation at 2,400 volts or less and typically do 7
not contain a metallic shield. In general, medium voltage cable 8
refers to cables that are classified for operation from above 9
2,400 volts up to 69,000 volts and typically include a metallic 10 shield. Power equipment is often designated by voltage class 11 which is based on the magnitude of the voltage with which the 12 equipment operates. Transmission class equipment generally 13 operates at or above 69,000 volts. Distribution class 14 equipment generally operates below 69,000 volts. In a utility 15 setting, medium voltage equipment is a subset of distribution 16 class and usually refers to equipment that operates above 2,400 17 volts to 69,000 volts. Low voltage equipment refers to 18 equipment that operates at 2,400 volts or less. All underground 19 distribution cables are low or medium voltage.
20 Q.
Please describe the construction of a low or medium 21 voltage cable.
22
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 9
A.
To help make my testimony on this subject easier to 1
follow, I have created Figure 2 below, which is a composite of 2
pictures showing various cable types, to illustrate the parts of 3
an insulated power cable. Detailed descriptions of the various 4
components are provided below the 5
figure.
6 7
Low and Medium Voltage Underground Cable Components 8
9 A.
A cable contains a conductor that carries the 10 electrical current. The conductor is made of either copper or 11
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 10 aluminum and is usually manufactured using stranded wires that 1
improve its flexibility. Because the conductor has 2
imperfections and non-uniformity that can cause electrical 3
stress in the overlying insulation layer, a thin semi-conducting 4
layer of material, known as the conductor shield, is applied 5
over the conductor to provide a smooth interface between the 6
conductor and the surrounding insulation.
7 The insulation layer on a cable supports the rated line-to-8 ground voltage between the conductor and outer cable layers --
9 that is, it prevents the electricity from leaving the cable 10 circuit, flowing into the environment and causing a voltage drop 11 in the cable that breaks the circuit.
12 The insulation on cables constructed in the 1960s and 1970s 13 was generally made of cross-linked polyethylene ("XLPE"), or 14 ethylene-propylene-rubber ("EPR"), which is also known as high 15 molecular weight polyethylene (HMWPE). The chemical 16 components of these materials are combined using reagents, heat 17 and pressure and then pumped, or extruded through a die, at high 18 temperature over the conductor and conductor shield.
19 An insulation shield, similar to the conductor shield, is then 20 applied to the insulation to provide a smooth interface between 21 the insulation and the outer cable layers.
22 Some medium voltage cables -that is, above 2.4 kV, also 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 11 include a metallic shield over the insulation shield. The 1
metallic shield can consist of helical copper or aluminum wire 2
strands, helical copper or aluminum tapes or longitudinal copper 3
or aluminum foil wrap. Some cables have a foil laminate and 4
wires. The longitudinal foil and, to a lesser degree, the 5
helical tapes provide a degree of moisture barrier (i.e., a 6
sheath) to the cable insulation but generally do not form a 7
hermetic seal.
8 An insulating jacket made of polyvinyl chloride or 9
polyethylene is then placed over the insulation, insulation 10 shield, and metallic shield, if there is one. The jacket 11 provides mechanical protection to the shield and insulation, 12 prevents corrosion of the metallic shield, and electrically 13 insulates the metallic shield from the surrounding environment.
14 The jacket is not a hermetic barrier and does not alone prevent 15 moisture intrusion into the insulation.
16 Q.
Are underground cables directly buried in the ground?
17 A.
They can either be directly buried in the ground or 18 pulled through buried conduits. Often more than one low or 19 medium voltage cable will be installed in a single conduit.
20 Q.
Please explain what a power cable failure is.
21 A.
A power cable failure prevents the cable from carrying 22 power to the intended location or equipment. This occurs when 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 12 the cable stops carrying current because of a failure or 1
interruption of the conductor, or when the cable insulation 2
stops supporting line to ground voltage because of a failure of 3
the insulation allowing some of the current to reach ground.
4 Q.
Please explain the term "line to ground" voltage?
5 A.
Power equipment is generally specified based upon 6
system voltage, or the voltage at which a particular system will 7
operate. System voltage or rated voltage is sometimes referred 8
to as the systems' class or by electrical engineers as the 9
line-to-line voltage or the difference in voltage between two 10 phase (e.g., line) conductors. Since the outside of the cable 11 is in contact with the ground or contains a metallic shield that 12 is grounded at one location, the voltage appearing between the 13 conductor and the metallic shield or the outside of the cable is 14 the line to ground voltage. The magnitude of the line to 15 ground voltage is equal to the system voltage divided by the 16 square root of three.
17 Q.
What is a cable failure?
18 A.
In the simplest terms, a failure occurs when a 19 component or apparatus no longer performs its intended function.
20 In this regard, a power cable failure prevents the circuit 21 from carrying power to the intended location or equipment.
22 Fundamentally, this means that the cable circuit stops carrying 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 13 current due to a failure or interruption of the conductor or if 1
the insulation stops supporting line-to-ground voltage due to a 2
breakdown of the insulation, or both.
3 Q.
What are the major causes of cable failures?
4 A.
Many cable failures occur from mechanical damage 5
during dig-ins, or as a result of workmanship errors in the 6
field during the installation of cables to accessories, such as 7
joints or terminations, or from the slow degradation of the 8
cable insulation due to moisture intrusion or exposure to 9
excessive heat. If the insulation is degraded, the cable may no 10 longer be able to support the line-to-ground voltage, resulting 11 in a breakdown or failure between the cable and ground or 12 shield. Electricity from the conductor will then discharge into 13 the surrounding environment, thus causing a drop in voltage and 14 the inability of the current to complete the circuit.
15 Q.
What is the major cause of insulation degradation in 16 non-EQ cables constructed in the 1960s and 1970s with XLPE or 17 EPR insulation that are exposed to significant moisture?
18 A.
A type of electrochemical degradation, known as "water 19 treeing" is the primary cause of the premature degradation of 20 the insulation leading to development of electrical trees. Water 21 treeing occurs in energized cables that are not constructed to 22 resist water intrusion but are nevertheless wetted or submerged 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 14 in water for periods of time. Water permeates the cable 1
insulation over time and forms channels that resemble trees.
2 Water trees are shown below in a photograph I took of a cross-3 section of cable insulation in which the conductor has been 4
removed. The insulation has been dyed so that the channels of 5
the water trees are revealed.
6 7
Example of water trees in cable insulation 8
9 Cables with extruded XLPE insulation manufactured in the 10 1960s and 1970s have experienced high failure rates when 11 subjected to conditions that form water trees leading to 12 electrical trees.
13
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 15 Q.
In your testimony, when you refer to cable insulation, 1
will you be referring to extruded XLPE and EPR insulation 2
manufactured in the 1960s and 1970s?
3 A.
Yes 4
Q.
Do water trees themselves necessarily cause the 5
failure of the insulation to support line to ground voltage?
6 A.
No. A water tree does not significantly break down the 7
dielectric (electrical) strength of the insulation and will 8
continue to support rated voltage, although a degree of partial 9
discharge of the electricity may occur at the locations within 10 the water trees that have carbonized. Over time, the partial 11 discharges (or electrical breakdown) will carbonize further, or 12 burn, the water tree channels to form electrical trees. When 13 sufficient electrical trees have formed through the insulation, 14 the insulation will break down, the cable will not be able to 15 support voltage and will therefore not be able to carry current.
16 Water trees usually form in areas of high electrical stress 17 within the insulation. For this reason, they usually form in the 18 insulation nearest the cable conductor.
19 Q.
Does XLPE and EPR cable manufactured today have the 20 same propensity to water treeing in wet environments.
21 A.
Generally, no. There have been technical developments 22 in the manufacture of XLPE and EPR cables, such as dry curing of 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 16 the cable, applying semi-conductive shields with substantially 1
reduced ionic content, and incorporating tree retardant 2
compounds in cross-linked polyethylene insulation which reduce 3
the propensity toward water treeing.
4 Q.
Can electrical trees form in the absence of water 5
trees?
6 A.
Yes. Occasionally, an electrical tree can form after 7
prolonged operation of a cable with something protruding into 8
the cable insulation, such as a portion of the conductor or the 9
insulation shield, but electrical trees formed by this mechanism 10 are manufacturing defects.
11 Q.
Are there tests that can assess the condition of 12 cable insulation on inaccessible cables?
13 A.
Yes there are. The staff of the Nuclear Regulatory 14 Commission in its guidance "Generic Aging Lessons Learned Report 15
("GALL") issued in December 2010 lists six maintenance or 16 diagnostic tests that the NRC determined are proven tests for 17 detecting deterioration of the insulation system in inaccessible 18 power cables due to wetting or submergence. NUREG-1801, Rev. 2, 19 Generic Aging Lessons Learned, Final Report (December 2010) at 20 XI E3-2 ("New GALL"), Exh. NYS00147D. The list in the New GALL 21 is not exclusive, and I will describe several tests that are not 22 explicitly listed in the New GALL but are relevant to the issues 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 17 in this proceeding. Maintenance and diagnostic tests are used 1
to assess the condition of inaccessible cables. All of these 2
tests require taking the cable out of service to fit test 3
equipment or sensors and each has advantages and disadvantages.
4 Some of the tests are destructive -- that is, the cable that is 5
tested will need to be replaced if it fails the test. Moreover, 6
the insulation on some cables may be weakened by destructive 7
tests even though they pass the test. Other tests are non-8 destructive -- that is, they assess the condition of the cable 9
insulation without necessarily harming or weakening it.
10 Q.
Please describe the destructive tests.
11 A.
Destructive tests can be considered "pass/fail" tests.
12 They can all be performed on both shielded and unshielded 13 cables. For example, the AC Voltage Withstand test subjects a 14 cable to a voltage at or above the voltage that the cable was 15 designed to withstand. Either the cable will withstand the 16 increased voltage or it will fail due to a defect in the 17 insulation, joint or termination. If there is a failure, it will 18 occur during controlled conditions rather than failing when the 19 cable is in service and expected to perform. If the cable fails, 20 then it must be replaced.
21 The step voltage test is a variation of the AC Voltage 22 Withstand test. DC instead of AC current is used, the voltage is 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 18 raised in stages, and the leakage current is monitored during 1
the test to determine if there are problems.
2 A voltage withstand test not listed in the New GALL is Very 3
Low Frequency ("VLF") testing. If a cable contains water trees, 4
VLF testing is more likely to convert them to electrical trees 5
during the test than the AC Voltage Withstand test. This is a 6
benefit of VLF testing because water trees will not necessarily 7
cause a breakdown in the dielectric strength of the cable 8
insulation but electrical trees will. Thus, a cable with water 9
trees may pass the AC Voltage Withstand test even though it 10 contains water trees that may eventually convert to electrical 11 trees and cause a cable failure in the future. Because VLF 12 testing converts existing water trees into electrical trees more 13 effectively than a simple AC voltage withstand test, it will 14 better force weakened insulation to fail during the testing 15 outage when the cable is not expected to perform and when it can 16 be repaired without disrupting operations or compromising safety 17 features. If a cable fails the VLF test, as with any withstand 18 test, it must be replaced.
19 Q.
Please describe the non-destructive tests listed in 20 the New GALL.
21 A.
The Insulation (dielectric) dissipation factor 22 compares the characteristics of the cable insulation 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 19 (dielectric) material to that of a near-perfect dielectric using 1
a standard capacitor and a capacitive bridge. The capacitive 2
bridge is used to determine the dissipation factor through the 3
known capacitance of a standard capacitor with that of the 4
unknown capacitance of the cable. It is generally non-5 destructive. This test only detects "gross" effects of the cable 6
-- that is, characteristics that affect the bulk of the cable 7
insulation, but does not detect localized problems. It is best 8
used on paper insulated cables that have appreciable dielectric 9
loss.
10 Partial Discharge Detection detects the minute electrical 11 noise (partial discharge or "PD") that is generated where 12 localized breakdowns are occurring in electrical equipment, 13 including in the insulation of cables and accessories, when 14 voltage is applied. As the voltage is raised, localized 15 breakdowns in the insulation - called partial discharge -
16 generate a signal that can be detected from the end of the 17 cable. The test takes advantage of the propagation velocity of 18 the signal through the cable to determine the location within a 19 cable that the PD is occurring-i.e., in a specific location 20 within the cable, or in a joint or termination. The magnitude of 21 the signal detected reflects the extent of the partial 22 discharge.
23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 20 In Time Domain Reflectometry, sometimes called cable 1
RADAR, a signal is sent through the cable from one accessible 2
cable end; the magnitude and timing of reflections returned to 3
the test equipment gives a measure of the insulation impedance 4
characteristics; the cable propagation velocity is used by the 5
test equipment to determine the location of the impedance.
6 Q.
In the New GALL, the AMP for inaccessible non-EQ low 7
and medium voltage cables states that "trending actions are 8
included as part of this AMP." Please explain what "trending 9
actions" are.
10 A.
The results of cable condition monitoring tests are 11 "trendable" if the performance of the cable on a later test can 12 be compared with the performance of the same cable on an earlier 13 test so that its relative performance over time can be assessed.
14 Trendable results are important because they provide information 15 about the rate of cable insulation degradation.
16 Q.
Are the results of the tests you have described all 17 trendable?
18 A.
No. The results of the destructive or pass/fail 19 tests, such as AC Voltage Withstand, Step Voltage and VLF, are 20 not trendable because they only tell you whether the cable 21 withstood the voltage on a particular occasion but do not reveal 22 anything specific about the relative condition of the cable 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 21 insulation on that occasion. Therefore, the results of two 1
tests at different times cannot be compared other than whether 2
the cable passed the second test.
3 The results of non-destructive tests such as Insulation 4
Dissipation Factor, PD and TDR can be trended. For example, a 5
comparison of PD test results might show partial discharge 6
occurring in a section of the cable that previously had shown no 7
discharge which could indicate increased cable insulation 8
degradation. Similarly, comparing test results of the 9
Insulation Dissipation factor test might reveal an increase in 10 the dissipation factor as the insulation ages. A comparison of 11 TDR tests may show variations in cable impedance along a tested 12 cable section from earlier tests, perhaps indicating a localized 13 change in the cable condition or environment.
14 Q.
Are all the tests listed in the New GALL equally 15 effective on different types of cable?
16 A.
No. The condition of cables without an intact 17 metallic shield around the insulation cannot be effectively 18 tested with PD or TDR. The signals evidencing the partial 19 discharges in the PD test or TDR test are minute and are much 20 more likely to be lost - a process called attenuation - in 21 unshielded than shielded cables, or even in taped shields that 22 have experienced some degree of corrosion, particularly in 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 22 longer cable circuits. PD and TDR are therefore much less 1
effective in low-voltage cables, most of which are unshielded.
2 Also, the test equipment is sensitive to electrical interference 3
in the vicinity. In addition, PD and TDR tests may be 4
ineffective in cables with helical tape shields that have 5
experienced some degree of corrosion, particularly in longer 6
cable circuits.
7 The pass/fail tests such as AC Voltage Withstand, Step 8
Voltage and VLF are effective on both shielded and unshielded 9
cables. However, their results cannot be trended so they give 10 almost no information about the actual condition of the cable 11 insulation short of breakdown. In sum, there is no one ideal 12 test to monitor the condition of a cable's insulation.
13 Q.
Please summarize Entergy's Aging Management Plan 14
("AMP") for non-EQ inaccessible low and medium voltage cables 15 exposed to significant moisture which was revised in response to 16 Staff's Request for Additional Information and follow-up 17 questions.
18 A.
Entergy revised its initial AMP for non-EQ low and 19 medium voltage power cables after the New GALL was issued.
20 Entergy's revised AMP was expanded to apply to low voltage power 21 cables from 400V to 2 kV as well as medium voltage power cables 22 from 2kV to 35kV which are exposed to significant moisture.
23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 23 Entergy Response (NL-11-032) to Request for Additional 1
Information, Aging Management Programs, Indian Point Nuclear 2
Generating Unit Nos. 2 &3 (Mar.28, 2011)("Entergy March 28 3
Response")Attachment 1 at 12-13, Exh. NYS000151. Significant 4
moisture is defined in the New GALL as periodic exposures to 5
moisture that last more than a few days-for example, cable 6
wetting or submergence in water. New GALL at XI E3-1, Exh.
7 NYS00147D. Entergy has indicated it will inspect for water 8
accumulation in manholes at least once every year. In addition 9
to the annual manhole inspections, Entergy will inspect manholes 10 after events such as heavy rain or flooding. The manhole 11 inspection frequency will be increased as necessary based on 12 evaluation of inspection results. Entergy March 28 Response, 13 at 12-13, Exh. NYS000151.
14 Entergy has indicated that cables that are exposed to 15 significant moisture will be tested at least once every six 16 years to provide an indication of the condition of the conductor 17 insulation. Test frequencies will be adjusted based on test 18 results and operating experience. Entergy also states that its 19 AMP will be implemented consistent with the corresponding 20 program described in the New GALL and that it will be 21 implemented prior to the period of extended operation. Entergy 22 March 28 Response, Attachment 1 at 12, Exh. NYS000151.
23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 24 Q.
Does Entergy's revised AMP contain any more detail?
1 A.
No.
2 Q.
In your opinion, does Entergy's revised AMP 3
demonstrate that the effects of aging on the intended 4
function(s) of non-environmentally qualified inaccessible low 5
and medium voltage cables that are exposed to adverse localized 6
environments will be adequately managed during the period of 7
extended operation?
8 A.
No it does not.
9 Q.
Please explain your conclusion that the AMP is 10 insufficient as it relates to the manhole inspection program.
11 Q. Preventing cable insulation degradation in the first 12 instance is a more effective aging management program than 13 testing the condition of cables to determine whether its 14 insulation has already degraded. Because water trees cannot 15 form in a cable in the absence of water, and almost all 16 electrical trees result from water trees, a robust program for 17 preventing water accumulation in manholes and conduits is 18 essential. Entergy's AMP does not describe the specifics of 19 such a program. Entergy simply provides a schedule of manhole 20 inspections but does not mention or commit to any of the 21 corrective measures listed in the New GALL if water is found, 22 such as the installation of permanent drainage systems, or sump 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 25 pumps and alarms. Entergy does not identify actions it will 1
take in the event water intrusion is a chronic problem not 2
sufficiently managed by the proposed schedule of maintenance 3
listed in the GALL.
4 Q.
In your opinion, is the AMP sufficient as it relates 5
to cable condition monitoring and testing.?
6 A.
No it is not. Entergy has provided so little specific 7
information, that it cannot demonstrate that its cable condition 8
monitoring program will reasonably assure the cables' continued 9
operation during the license renewal period.
10 Q.
What information is missing?
11 A.
As an example, Entergy has not given any information 12 about the number of non-EQ inaccessible power cables exposed to 13 adverse localized environments.
14 Q,
Why is the number of cables important?
15 A.
In its License Renewal Application, Entergy has 16 committed to implement its AMP for non-EQ inaccessible power 17 cables prior to the period of extended operation at IP 2 and 18 IP3. The license for IP 2 expires in September 28, 2013, and its 19 period of extended operation begins after that date. To fulfill 20 its commitment, Entergy will have to test all the relevant 21 cables at IP 2 within the next 20 months and will have to be 22 able to schedule enough planned outage time to accomplish all 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 26 the testing.
1 Q. Can you estimate the number of cables that can be 2
tested in a normal work shift.
3 A. It depends on the type of test, the testing 4
equipment, time required to obtain switching outages, and the 5
technicians performing the test. Partial discharge testing can 6
be performed at a rate of 3-5 cables per normal work shift of 7
10-12 hours; a voltage withstand test can be performed at a rate 8
of 6-12 cables per normal work shift.
9 Q. Can you assess whether Entergy will be able to test all 10 the relevant cables at IP2 before the period of extended 11 operation.
12 A. I cannot because Entergy has provided no information 13 about the number of relevant cables at either IP 2 or IP3.
14 Q.
What other information is missing from Entergy's 15 revised AMP?
16 A.
The revised AMP does not identify anything about the 17 characteristics of the non-EQ inaccessible cables that are 18 exposed to significant moisture or identify testing methods that 19 are appropriate for the types of cable the AMP will manage. It 20 does not identify their location, their number, their function, 21 or their physical characteristics. However, as the Brookhaven 22 National Laboratory in a report prepared for the NRC in 2010 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 27 explained, the selection of an appropriate testing technique 1
depends on cable characteristics such as voltage rating, cable 2
insulation or jacket material, cable shielding and cable 3
location. NUREG/CR-7000, BNL-NUREG-90318-2009, Essential 4
Elements of an Electric Cable Condition Monitoring Program, 5
Office of Nuclear Regulatory Research (January 2010) ("NUREG/CR-6 7000") at 3-20, Exh. NYS000148.
7 For example, I have assumed that the relevant cables are 8
extruded construction for which certain tests would generally be 9
inappropriate, such as DC Step Voltage or Insulation Dissipation 10 Factor. Those same tests, however, would be effective for 11 paper-lead cables, another cable type that utilities frequently 12 used in the 1960s and 1970s.
13 Similarly, whether or not a cable has a metallic shield 14 over the insulation will determine whether certain test methods 15 such as PD or TDR will be effective. If an unshielded cable more 16 than a few hundred feet long is tested with the PD method, then 17 the test results may show that partial discharge is not 18 occurring when it is - i.e. a false negative. That is because 19 the signal that establishes whether or not partial discharges 20 are occurring due to insulation degradation becomes attenuated 21 in an unshielded cable or is disrupted by neighboring electrical 22 equipment.
23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 28 Because Entergy has failed to provide any information about 1
the characteristics of the relevant cables or selected test 2
methods appropriate for those characteristics, it has not 3
explained what the acceptance criteria are for the tests it will 4
conduct. For example, a voltage withstand test must apply 5
voltage to the cable that is at or above the cable's rating to 6
see if the cable can withstand the stress of normal operation.
7 If a lower voltage is applied, the cable may "pass" the test 8
when it would have failed a test with higher voltage. Similarly, 9
in the Partial Discharge Test, the partial discharges that occur 10 at the location of degraded insulation are measured in 11 picocoulombs. If Entergy applies the PD test to certain cables, 12 it must describe the level of picocoulomb discharge that is 13 acceptable and the level that is not. Moreover, its acceptance 14 criteria must be consistent with industry practice. The 15 industry acceptance criterion for PD testing is no more than 5pC 16 discharge. Otherwise, the Board cannot know whether degraded 17 cables that should be repaired or replaced are allowed to remain 18 in place because the test was insufficiently rigorous.
19 Q.
Does the revised AMP include trending actions?
20 A.
No. The revised AMP does not mention trending and 21 because it does not select any particular tests, it is not 22 possible to know whether test results will be trendable or if 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 29 Entergy intends to use trending in its AMP. The ability to trend 1
test results is extremely significant because it provides 2
information about the rate of cable insulation degradation and 3
that information can be used preventively to repair or replace 4
cables before they fail. Thus, if Entergy chooses a non-5 trendable voltage withstand test on shielded medium voltage 6
cable over trendable tests such as PD or TDR, it will not obtain 7
information that could be used proactively to repair or replace 8
cables before they are on the verge of failure.
9 Q.
Are there adverse environmental conditions, other than 10 moisture intrusion, that can cause the degradation of power 11 cable insulation?
12 A.
Yes. For example, thermally induced cable degradation 13 occurs when a power cable is operated above its rated 14 temperature, and the insulation melts or burns causing the 15 insulation's dielectric strength, that is, its voltage 16 insulating properties, to degrade to the point of an electrical 17 breakdown.
18 Q.
Is thermal degradation a problem that must be 19 considered in the aging management of inaccessible low and 20 medium voltage power cables?
21 A.
Yes. As I discuss below, there may be uncertainty 22 about the installation environment of inaccessible power cables 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 30 such as the thermal resistance of the soil in which the cables 1
are buried. Moreover, underground power cables may be in close 2
proximity to each other, either directly buried underground or 3
in cable conduits which may cause the mutual heating effect, 4
discussed below.
5 Q.
What causes thermal degradation of cables?
6 A. Thermal degradation can occur in essentially three 7
situations. First, the thermal resistance of the environment 8
through which an underground cable passes may be too high for the 9
heat generated by the current to pass out of the cable and into 10 the surrounding soil. For accessible cables in air, there may be 11 inadequate thermal convection and radiation to dissipate the 12 heat. Second, the ambient temperature around the cables may be 13 greater than the cable was designed to withstand because of an 14 external heat source, such as a steam line, hot water pipe or 15 inadequate ventilation. External heat sources can affect cable 16 temperatures when in parallel or crossing cable circuits or when 17 occupying the same conduits or trench areas. And third, heat 18 from other cables in close proximity, particularly in 19 underground conduits, will cause the temperature to rise in the 20 vicinity of the subject cable and cause a mutual heating effect.
21 Q.
Has Entergy prepared an AMP for non-EQ inaccessible 22 power cables that are exposed to adverse localized environments, 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 31 such as excessive heat.
1 A.
Entergy has not prepared such a plan. Nor has Entergy 2
shown that no plan is necessary by demonstrating that none of 3
its inaccessible cables are ever operated above their rated 4
temperatures.
5 Q.
Does insulation degrade faster when exposed to 6
excessive heat than excessive moisture?
7 A.
This depends on the extent of the heating. Problems 8
in cables caused by moisture intrusion generally develop over 9
months or years. Low or moderate excessive heating can 10 accelerate cable aging over months or years, while high 11 excessive heating can seriously degrade a cables condition 12 quickly, within weeks to months. In extreme cases, serious 13 degradation can occur even more quickly.
14 Q.
Have any studies been done on the effect of excessive 15 heat on low-voltage cables.
16 A.
Yes. The Sandia National Laboratory commissioned a 17 study entitled Aging Management Guideline for Commercial Nuclear 18 Power Plants - Electrical Cable and Terminations, SAND96-0344.
19 The study report was issued in 1996 and concluded that "thermal 20 embrittlement of insulation is one of the most significant aging 21 mechanisms for low-voltage cable." SAND96-0344, Aging Management 22 Guideline for Commercial Nuclear Power Plants - Electrical Cable 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 32 and Terminations (September 1996) at 1-3. Exh. NYS00156A.
1 Because all the safety-related power cables at IP 2 and 3 2
are low-voltage, Entergy's failure to explain how it will manage 3
the effects of excessive heat on the insulation of non-EQ 4
inaccessible low-voltage cables is a critical omission from its 5
License Renewal Application. Without such a plan, Entergy has 6
failed to demonstrate that its safety-related low-voltage power 7
cables will continue to perform their critical function during 8
the period of extended license operations.
9 Q.
Are there tests that can determine whether 10 inaccessible cables are operating in excessively hot 11 environments?
12 A.
Yes. The inaccessible cables could be retrofitted with 13 a fiber optic sensor that provides temperature readings along 14 the length of the cable every meter (3.3 feet). The results of 15 this test method, known as Distributed Temperature Sensing 16 (DTS), can be compared over time and can reveal whether a hot 17 spot in a cable is getting worse.
18 Alternatively, discrete thermocouple temperature monitoring 19 at known hot spots at inaccessible locations, perhaps by 20 inserting a thermocouple up to a few hundred feet into a conduit 21 occupied by low or medium voltage cable, can be used as an 22 alternative to DTS or (on accessible cables) thermographic 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 33 testing on accessible cables. Entergy can identify the critical 1
locations to be monitored through the use of an integrated 2
approach that may include (a) the review of Environmental 3
Qualification (EQ) zone maps that show radiation levels and 4
temperatures for various plant areas, (b) consultations with 5
plant staff that are cognizant of plant conditions, (c) 6 performing soil thermal resistivity tests for buried cables, and 7
(d) the review of relevant plant-specific and industry operating 8
experience. The results of the temperature monitoring can be 9
trended, and continuous monitoring may be possible. Fire 10 protection systems in some buildings utilize DTS-based systems 11 to check the temperature of zones within a building.
12 Q.
Under what circumstances are corrective actions 13 required for cable overheating?
14 A.
Power cables have emergency operating temperature 15 limits intended to address short incursions above rated 16 temperature and load. If DTS or discrete temperature tests 17 indicate that cables are consistently operating at temperatures 18 above their normal operating limits for longer than 19 permissible emergency durations, or more frequently than 20 periodic emergencies are allowed, or above emergency operating 21 limits at any time, then corrective actions must be taken. Those 22 actions include, but are not limited to, removing additional 23
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 34 thermal insulation that may be placed around the cables, 1
reducing the number of cables installed in close proximity (to 2
mitigate mutual heating), replacing existing cables with larger 3
conductor cables to decrease heat losses, lowering the ambient 4
temperature in which the cables are installed, and replacing 5
high thermal resistivity soils around the cable conduits or 6
direct buried cables with a lower thermal resistivity thermal 7
backfill.
8 Q.
Please summarize your conclusions about whether 9
Entergy has demonstrated that it will manage the aging affects 10 of non-environmentally qualified inaccessible power cables 11 exposed to adverse localized conditions.
12 A.
Entergys AMP is lacking in substantive detail, and 13 thus Entergy has failed to demonstrate that it will manage the 14 effects of aging of non-EQ inaccessible cables exposed to 15 significant moisture or excessive heat so that they will be able 16 to perform their intended function for another 20 years during 17 the extended licensing period of operation.
18 The following specific critical details about the non-EQ 19 inaccessible power cables are missing from Entergy's LRA 20
- Age of the cable circuits 21
- The number of cable circuits 22
Pre-filed Written Testimony of Earle C. Bascom III Contention NYS-6/7 35
- The lengths of cable circuits 1
- The voltage class of the cables 2
- The types of cables, including insulation type 3
- The types of testing that will be performed 4
- The acceptance criteria for each of the tests 5
- The corrective actions 6
- The management of the effects of aging due to thermal 7
stress 8
- Justification for failing to consider aging due to 9
thermal stress 10 Because of this absence of substantive detail, the 11 licensing board cannot adequately assess if Entergys LRA should 12 be approved for the continued operation of IP2 and IP3.
13 Q.
Does this conclude your testimony?
14 A.
Yes.
15 I have reviewed all the exhibits referenced herein. True 16 and accurate copies are attached.
17 18 19 20 21 22