ML18153B055
| ML18153B055 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 08/23/1994 |
| From: | Casto C, Mark Miller NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18153B054 | List: |
| References | |
| 50-280-94-18, 50-281-94-18, GL-89-10, NUDOCS 9409120044 | |
| Download: ML18153B055 (20) | |
See also: IR 05000280/1994018
Text
.*
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, N.W., SUITE 2900.
ATLANTA, GEORGIA 30323-0199
Report Nos.:
50-280/94-18 and 50-281/94-18
Licensee:
Virginia Electric and Power Company
5000 Domimion Boulevard
Glen Allen, VA
23060
Docket Nos.:
50-280 and 50-281
License Nos.:
Facility Name:
Surry 1 and 2
Inspection Conduc~e~ul~ 25--29, i_:: .
Inspec]r: ~/+-~
c.,1--M.
.
111 er
Aecom anying Personnel: R. Cain, Consultant, INEL
T. Scarbrough, Office of Nuclear
D. Tamia, Intern
Approved by: /_~-./*~
~ief
Scope*
Test Programs Section
Engineering Branch
Division of Reactor Safety
SUMMARY
~y9Y
Dae Signed
Reactor Regulation
<t/~J/7 f
Date Signed
This special, *announced inspection was performed at the Surry Nuclear Plant to
examine the implementation of the licensee's motor-operated valve (MOV)
program to meet *commitments in response to Generic Letter (GL) 89-10, "*Safety-
Rel ated Motor-Operated Valve Testing and Surveillance." The inspectors
utilized the guidance provided in Temporary Instruction (TI) 2515/109 (Part
2), "Inspection Requirements for Generic Letter 89-10, Safety-Related Motor-
Operated Valve Testing and Surveillance." As delineated in Part 2 of TI
2515/109, this inspection was the initial review of the licensee's MOV program
implementation in response to GL 89-10.
The inspectors reviewed six MOVs in detail including selected portions of
design calculations, test packages, and diagnostic signature traces. In
addition, three MOVs in three different groups were reviewed for comparison
9409120044 940823
ADOCK 05000280
G
2
purposes.
The inspectors also reviewed followup issues from the previous NRC
inspection of the MOV program {TI 2515/109, Part 1) conducted November 18-22,
1991, and documented in NRC Inspection Report Nos. 50-280,281/91-32.
Results
In the areas inspected one non-cited violation was identified for the misuse
of design information in a thrust calculation.
NCV-50-280/94-18-0l, MOV Design Thrust Calculation Error (Section 2.3)
The overall conclusion was that the licensee was in the process of
implementing a very good GL 89-10 MDV program.
However, several concerns
identified during the Part 1 inspection and items identified during this
inspection will require further NRC evaluation prior to closure of GL 89-10.
These concerns pertain to 1) MOV thrust calculations; 2) use of the Kalsi
study for overthrust conditions; 3) MDV grouping; 4) valve factor assumptions;
5) valve stem friction coefficient; 6) periodic verification; and, 7) MDV
failures addressed in NRC Information Notice IN 94-10.
In addition, ten MDVs
in Unit 2 remain for dynamic testing during the next refueling outage.
Several minor modifications remain for five MOVs (Section 2.3).
Based on the evaluation completed during this inspection the following
strengths were noted in the licensee's GL 89-10 program:
The System Engineering Department's support of both the design-basis
parameters and testing of the MOVs through the use of the "Testing And
Results Docum~nts" made a significant contribution to the GL 89-10
program. (Section 2.1)
The licensee evaluates the test results for DP tested valves prior to
any mode change during the MDV testing phases. (Section 2.3)
A large number of MDVs have been tested.
(Section 2.3)
The MDV program was well organized and documentation was detailed and
complete .. (Section 2.0)
Both the corporate engineering staff and the on-site personnel exhibited
knowledge and expertise.
(Section 2.2 and 2.3}
Except as noted above, the inspectors concluded that the licensee was in the
process of implementing an effective program in response to GL 89-10 thereby
ensuring the design-basis capability of MDVs at the facility .
REPORT DETAILS
1.
Persons Contacted
Licensee Employees
- R. Beger, Nuclear Operations Support
- W. Benthall, Supervisor, Licensing
- R. Blount, Supervisor, Maintenance
- D. Christian, Assistant Station Manager
- P. DeTine, Project Engineer, Nuclear Engineering
- R. MacManus, Supervisor, System Engineering
- J. McCarthy, Superintendent, Operations
- E. Smith Jr., Manager, Quality Assurance
- J. Staffer, MOV Coordinator, Maintenance
- A. Wright, MOV Engineer, System Engineering
Other licensee employees contacted during this inspection included
engineers, technicians, and administrative personnel.
NRC Resident Inspectors
- M. Branch, SRI
- Attended exit interview
Acronyms and initialisms used in this report are listed on the last
page.
2.0
GENERIC LETTER (GL) 89-10 "SAFETY-RELATED MOTOR-OPERATED VALVE [MOV]
TESTING AND SURVEILLANCE"
(2515/109)
On June 28, 1989, the NRC issued GL 89-10, which requested licensees and
construction permit holders to establish a program to ensure that switch
settings for safety-related MOVs were selected, set, and maintained
properly. Subsequently, six supplements to the GL have been issued.
NRC inspections of licensee actions implementing commitments to GL 89-10
and its supplements have been conducted.based.on.guidance provided.in
Temporary Instruction (TI) 2515/109, "Inspection Requirements for
Generic Letter 89-10, Safety-Related Motor-Operated Valve Testing and
Surveillance." TI 2515/109 is divided into Part 1, "Program Review,"
and Part 2,- "Verification of Program Implementation."
The focus of this inspection was to evaluate, in depth, the test results
of a sample of six MOVs that had been dynamically tested and review the
licensee's corrective actions for the concerns identified during the
GL 89-10, Part 1 MOV inspection. The test results and engineering
documentation were examined for the MOVs listed below:
Valve No.
l-CH-MOV-1286B
l-CH-MOV-1286C*
MOV Function, Size, and Type
B Charging Pump Normal Discharge Valve
3 inch flex wedge gate - Velan
1-CH-MOV-1287A
2-CH-MOV-1287A*
1-FW-MOV-160A
1-FW-MOV-1608*
1-SI-MOV-1863A
1-SI-MOV-I890C
2-SI-MOV-2842
2
A Charging Pump Alternate Discharge Valve
3 inch flex wedge gate - Westinghouse
Auxiliary Feedwater Cross Connect Valve
6 inch flex wedge gate - Crane
Low Head Safety Injection to High Head
Safety Injection Cross-Connect Isolation
Valve - 8 inch solid wedge gate - Aloyco
Low Head Safety Injection Pump Discharge
Valve to RCS Cold Leg Injection - 8 inch
double disc gate - Anchor Darling
Alternate High Head Safety Injection to
Cold Leg Isolation Valve - 4 inch double
disc gate - Anchor Darling
- Indicates MOV's test data was reviewed for comparison purposes.
The inspectors verified that the system design-basis differential
pressures (DP) and flows used for diagnostic testing of the GL 89-10
Program MOVs listed were reasonable and correct. This examination
included review of piping and instrumentation drawings; design-basis
calculation results of the expected differential pressures; the sizing
and switch setting calculations; and diagnostic test data.
The
inspectors also conducted a walkdown of the MOVs.
The inspectors found the licensee's MOV program documentation,
procedures, test packages, and technical reports were detailed, complete
and well organized.
The licensee's engineering personnel were
knowledgeable and cooperative in assisting the inspectors.
Except as
noted in the following paragraphs, the inspectors concluded that the
licensee was in the process of implementing an effective program in
response to GL 89-10 thereby ensuring the design-basis capability of
MOVs at the facility.
2.1
Design-Basis Reviews
The inspectors reviewed the licensee's design-basis documentation (DBD)
to determine and verify its adequacy for all the MOVs in the licensee's
GL 89-10 program including the nine MOVs examined during this
inspect ion.
In addition, recommended action.
11 a
II of GL 89-10 requested
licensees determine the maximum differential pressure and flow expected
for both normal and abnormal (design-basis accident) conditions.
The
inspectors verified these values were used in thrust calculations.
These follow-up reviews were performed to determine and verify that
changes were implemented to address concerns identified during the
GL 89-10, Part 1 inspection conducted in November 1991. That inspection
identified several concerns related to the review of the design-basis
calculations. At that time the design-basis differential pressure
3
calculations did not include flow rates (as discussed in GL 89-10).
In
addition, .the degrading effects of high ambient temperature on the
output torque of MDV motors had not been considered.
Limitorque had not
yet issued their Potential Part 21 Notice dated May 13, 1993, and the
Technical Update 93-03 dated September 1993, that discussed the effects
of elevated temperature on motor torque.
The inspectors reviewed the licensee's General Nuclear Standard, STD-GN-
0002, Revision 2, dated March 1994, "Motor-Operated Valve Sizing &
Calculations" that addressed Limitorque's Potential Part 21 Notice.
In
addition, electrical calculations (EE-0306 and EE-501) were examined to
verify that high ambient temperature effects were included.
The
inspectors verified that these electrical calculations were revised to
include the effects of elevated temperature on both motor torque and
thermal overloads.
During this inspection, the inspectors reviewed the documentation
referenced in the "Differential Pressure Calculations" and "Testing
Basis and Results Documents" {TBRD) to verify that the maximum flow and
differential pressure were used in the thrust calculations. The
documentation reviewed included the operational procedures, system flow
drawings {P&ID), pump curves, the system description documents in the
Operator.Development Program for the Safety Injection, Charging,
Feedwater, Auxiliary Feedwater, and Chemical and Volume Control Systems .
The System Engineering Department developed a series of DBDs identified
as GL 89-10 TBRD.
The TBRDs supplemented the Nuclear Engineering
design-basis Galculations by providing design-basis flow and
differential pressure test parameters. Additionally, evaluations and
conclusions for the DP test results were included in the TBRDs.
The
TBRDs provided a description of the limiting condition assumed in the
thrust calculations at design-basis flow and DP.
The DP test results
were analyzed and compared against the thrust calculations to verify
their adequacy.
The inspectors concluded the TBRDs addressed the flow
parameter and provided a method of interfacing between design
engineering and the site for both testing and analysis.
The TBRDs made
a significant contribution to the GL 89-lO_program and are-considered a
strength in the MOV program.
The inspectors verified the licensee's MOV calculations for DP,
electrical degraded grid voltage, flow, temperature, design thrust, and
torque addressed the recommendations in GL 89-10.
The inspectors
verified that degraded grid calculations were included to ensure that
the lowest motor terminal voltage commensurate with design-bases
conditions was factored into the determination of thrust ratings. The
inspectors also verified that the licensee satisfactorily addressed the
design, replacement and testing of thermal overloads in the electrical
circuits for the MOVs.
In the areas inspected the inspectors concluded the licensee had
adequately implemented the design-basis review .
4
2.2
MOV Sizing and Switch Setting
The inspectors reviewed the licensee's General Nuclear Standard STD-GN-
0002, "Motor-Operated Valve Sizing and Calculations," Revision 2, dated
March 1994,- to determine the thrust calculations used for the six
sampled valves.
STD-GN-0002 specified that the standard industry
equations for calculating thrust for gate and globe valves was to be
used.
The licensee used a valve factor (VF) of 0.30 for flex wedge gate
valves and 0.20 for parallel disc gate valves. A valve factor of 1.10
was used for globe valves.
For Westinghouse valves, the licensee used
data provided by the valve vendor, where available, or assumed a valve
factor of 0.45 or 0.55.
The valve orifice diameter was used in the
valve disc area calculations. A stem friction coefficient (SFC) of 0.15
was used in the calculations for the minimum required torque.
The
minimum required thrust, including packing load and stem rejection
force, was then adjusted by the use of a multiplying factor of 1.15 to
account for variations in valve factor, potential load sensitive
behavior (also known as "rate-of-loading"), and other phenomena.
The upper and lower thrust ~indow settings were adjusted for diagnostic
inaccuracies and torque switch repeatability. The licensee had
addressed the concerns discussed in Limitorque Maintenance Update 92-2
with respect to torque switch repeatability. This information had been
incorporated into the General Nuclear Standard, STD-GN-0002.
Limiter plates were not installed on all their GL 89-10 valves.
Further, the licensee assumed a stem friction coefficient of 0.15 and
did not routinely measure torque.
The inspectors discussed with the
licensee the possibility of exceeding the actuator's torque rating by
increasing the torque switch setting to achieve the desired thrust
output.
The licensee had taken the spring pack capability rating and
motor torque rating and converted these values to thrust using an
assumed stem factor. If the "as left" thrust readings approached the
spring pack or motor capability rating, an engineering evaluation was
performed.
The inspectors noted that the spring pack and motor
capability were computed using a stem friction coefficient of 0.15.
The
licensee's. intentions are to use the_stem friction coefficient
information from the EPRI prediction program and apply it to MOVs in
their program.
The licensee's justification for the use of a 0.15 stem
friction coefficient factor and the use of the EPRI information will
require further NRC evaluation prior to closure of GL 89-10.
As
discussed in Item 5 of Section 2.7 the inspectors were concerned about
the applicability of the stem friction coefficient data obtained by EPRI
to the Surry MOVs.
In the areas inspected, the inspectors concluded the licensee was
implementing an effective program to meet the recommendations of
However, further NRC evaluation will be required prior to
closure.
5
2.3
Design-Basis Capability
The inspectors reviewed the licensee's static and dynamic test data for
the sampled MOVs.
The licensee had completed static tests for 188 of
As of June 1993, the licensee had completed 46%
of the differential pressure (DP) testing on rising stem, testable
valves.
The licensee's intentions for completion of the GL 89-10
program are to use grouping and plant specific data for the non-tested
MOVs.
The licensee used guidance from the Generic Letter 89-10,
Supplement 6 and separated the MOVs into 37 different groups.
Their
intentions were to test a minimum of 30% of the MOVs in a group and at
least two MOVs in groups containing three or more MOVs.
The MOV
grouping was established by selecting the same type of valve and
operator in the same type of application. This selection was further
defined by valve manufacturer, type, model, size, and manufacturer's
drawing number.
In situations where a MOV was used in both high and low
DP pressure systems, the test results from the high DP test was used to
bound the lower pressure application. This methodology would result in
the testing of 58% of the testable MOVs.
The inspectors considered the
grouping technique to be generally consistent with the recommendations
in the GL 89-10.
However, the licensee had eight groups with only two
MOVs in each group.
The intent was to test only one of the two MOVs in
each of these groups.
The inspectors did not consider this consistent
with recommendations in Supplement 6 of GL 89-10.
Further, testing only
one valve in each group limits consistency of test results between
groups.
The inspectors concluded further NRC evaluation in this area
would be required prior to closure of GL 89-10.
The licensee had four MOVs in their program with motor brakes installed,
l-RH-MOV-1720 A/Band 2-RH-MOV-2720 A/8.
The licensee compared the
calculated minimum required thrust against the motor capability for
these limit open MOVs.
There was approximately 16,000 ft-lbs of
additional (extra) thrust available to compensate for the possible added
drag due to the motor brakes.
However, the inspectors determined
further NRC evaluation concerning motor brakes would be required prior
to closure of GL 89-10.
The licensee had operability reviews performed for the MOVs from the
requirements in Procedure SES-3.03, Revision 2, "Controlling Procedure
Providing Guidelines For Addressing MOV Design Issues." These reviews
were completed prior to returning the MOVs to service after design-basis
DP testing. There were no operability concerns by the inspectors s i nee . ~ ...
design-basis DP testing was conducted when the plant was in the shutdown
mode.
The acceptance criteria for the review was developed to evaluate
thrust at flow cutoff with the calculated minimum required thrust. This
evaluation had three cases. Case 1 was where test DP was equivalent to
design-basis DP.
Case 2 was where test DP was at least 80% or greater
than design-basis DP.
For these valves, the licensee used the ratio of
test DP to design basis DP and multiplied this by the thrust at flow
cutoff. Case 3 was where test DP was less than 80% design-basis DP.
For these cases, the licensee performed a qualitative review of the
thrust margin.
In all three cases, the licensee checked for margin
6
between the required thrust from the dynamic test and the calculated
minimum required thrust. The required thrust was also compared to the
thrust measured at control switch trip (CST).
Load sensitive behavior
was also checked by comparing CST thrust during dynamic testing with CST
thrust during static testing.
The inspectors, accompanied by licensee engineering personnel, reviewed
diagnostic traces for the sampled MOVs and several other selected MOVs.
Licensee personnel were knowledgeable in the use of the VOTES system and
the VOTES methodology of marking the diagnostic traces.
The inspectors
considered this to be a strength in the licensee's MOV program.
However, the inspectors noted that flow cutoff for valve 2-SI-MOV-2842
appeared to be improperly marked.
Licensee personnel agreed and
immediately revised the point marked for flow cutoff and verified that
an operability concern did not exist. Further NRC review of the
diagnostic traces indicated that the non-conservative marking of flow
cutoff for 2-SI-MOV-2842 was an isolated case.
The licensee's method of comparing thrust at flow cutoff against the
calculated minimum required thrust was developed to account for
variations in valve factor, load sensitive behavior, and other
uncertainties. The licensee had several valves (e.g., 2-SI-MOV-2864A
and l-CH~MOV-1287C) where the DP test thrust results were in excess of
that predicted by this methodology.
In all cases, the licensee took
immediate action to correct any deficiency and evaluate the impact on
the other MOVs in the group.
The inspectors considered this action
appropriate for evaluating deficiencies. However, these examples
indicated that this methodology was not always bounding.
The licensee
used both in-plant and industry test results to set up MOVs for design-
basis capability.
For MOVs that are not dynamically tested, the
licensee's methodology for "setting up" the MOVs from both in-plant and
industry test results will require additional NRC review.
The
licensee's justification for ensuring design-basis capability will
require further NRC evaluation as part of GL 89-10 closure.
The inspectors reviewed Memorandum "MOV Evaluations Supplement To Design
Basis Review Of l-SI-MOV-1842 Surry Power Station NIT 1 NP::-:2319" dated
June 27, 1994.
The purpose of this memorandum was to document the
further review of MOV operator "capability" regarding minimum required
thrust.
The minimum required thrust calculations were included in the
review.
The "capability" calculation used "stall torque" in the open
direction and used "stall efficiency" in the closed direction. The term
"stall torque" was misused.
Stall torque is defined as the torque at
zero speed (20 ft.lbs). The licensee used the derated torque at rated
speed (13 ft.lbs).
The open direction calculation used the motor rated
torque (derated for high ambient temperature and degraded voltage)
multiplied by 1.10 to derive "stall torque." However, in the closed
direction, the licensee misused the "stall efficiency" selected from
Limitorque's guidelines. Section 7 of Limitorque Maintenance Update 92-
1 indicates that "stall efficiencies" are not to be used to calculate
MOV capability. The use of "stall efficiency" in the closed direction
calculation was in violation of NRC requirements.
7
Criterion III, Design Control, requires, in part, that "design control
measures shall provide for verifying or checking the adequacy of
design ... " The inspectors reviewed the calculation to verify
operability of the MOV.
The licensee used a DP derived from the
"mispositioning" scenario that required recovery to the closed position
(non-safety position}. Licensee personnel recalculated the minimum
required thrust using a lower DP derived from a mispositioning scenario
that required recovery to the open (safety} position.
Further, licensee
personnel recalculated the motor capability using torque (13 ft-lbs
derated for high ambient temperature and degraded voltage}, an
application factor of 0.9, and the pullout efficiency. After the
recalculation, the motor had sufficient capability to meet design-basis
requirements.
The inspectors considered this adequate and did not
identify an operability concern with 1-SI-MOV-1842. * However, this NRC
identified violation is not being cited because criteria specified in
Section VII.B of the NRC Enforcement Policy were satisfied. The
violation was of minor safety significance and there was no operability
concern.
The misuse of "stall efficiency" in the thrust calculation is
identified as non-cited violation NCV-50-280/94-18-01, MOV Design Thrust
Calculation Error.
The inspectors reviewed additional "engineering evaluations" to
determine if any other MOVs used "stall torque" or "stall efficiency."
Six other MOVs were identified that misused the term "stall torque," but
did not use "stall efficiency." These MOVs were 1-RS-MOV-155 A/B, 1-SI-
MOV-1862 A/B, and 2-SI-MOV-2862 A/B which are Xomox plug valves.
The
actual torque value used was rated nominal torque at rated speed
(derated for high ambient temperature and degraded voltage}.
Further,
these MOVs used an application factor of 0.9 and pullout efficiency.
The inspectors did not identify any operability concerns with these
valves.
In addition, as part of their own evaluation, the corporate Nuclear
Engineering Department had recommended a gear change for these MOVs to
improve their margins.
Engineering also recommended that the operator
for 1-SI-MOV-1842 be upgraded to a larger size. The licensee stated all
these MOVs will be.modified during the*next.refuelingoutages.
The inspectors concluded the licensee had been implementing an effective
MOV program to verify design-basis capabilities. However, further NRC
evaluation will be required prior GL 89-10 closure.
2.4
Periodic Verification of MOV Capability
Recommended action "d" of the generic letter requests the preparation or
revision of procedures to ensure that adequate MOV switch settings are
determined and maintained throughout the life of the plant. Section "j"
of the generic letter recommends surveillance to confirm the adequacy of
the settings. The interval of the surveillance was to be based on the
safety importance of the MOV as well as its maintenance and performance
history, but was recommended not to exceed five years or three refueling
8
outages.
Further, GL 89-10 recommended.that the capability of the MOV
be verified if the MOV was replaced, modified, or overhauled to an
extent that the existing test results are not representative of the MOV.
The inspectors found that GL 89-10 MOVs were in the process of being
included in the licensee's database and that the database contained
model preventive maintenance work orders that specified VOTES diagnostic
testing at a three refueling outage or five year frequency.
The
diagnostic testing was not specified to be performed at DP; that is,
only static diagnostic testing would be performed.
The licensee's
criteria for test performance and acceptance of periodic verifications
and its justification that the criteria are adequate will require
further NRC evaluation prior to closure of GL 89-10.
The inspectors verified that post maintenance testing for different
maintenance operations was specified in the licensee's electrical and
mechanical Post Maintenance Test/Verification matrices.
Comprehensive
(static) diagnostic testing was required following valve replacement or
repair.
For packing adjustment, thrust verification was specified.
Licensee personnel were questioned as to why only static testing was
required for valve replacement.
The inspectors were informed that a DP
test should be performed for any valve replacement and that it was
provided.for as a "verification" on the related matrix. Only static
testing was considered necessary for a repair unless the repair might
affect the functioning of the valve. If functioning was affected, it
should be considered a modification rather than maintenance and the need
for DP testing should be evaluated.
The inclusion of "verification" DP
testing for the matrix that covered valve replacement was confirmed by
the inspectors.
The inspectors concluded that the specified testing was
appropriate.
The inspectors concluded that the licensee's periodic verifications were
not fully implemented.
Complete implementation, including adequately
justified test methodology and acceptance criteria, will require further
NRC evaluation prior to closure of GL 89-10.
The licensee was
implementing a satisfactory post maintenance testing program for the
MOVs.
2.5
MOV Failures, Corrective Actions, and Trending
Recommended action "h" of the generic letter requests that licensees
analyze and justify each MOV failure and corrective action.
The
documentation should include the results and history of each as-found
deteriorated condition, malfunction, test, inspection, analysis, repair,
or alteration. All documentation should be retained and reported in
accordance with plant requirements.
It is also suggested that the
material be periodically examined (every two years or after each
refueling outage after program implementation) as part of the monitoring
and feedback effort to establish trends of MOV operability .
9
The licensee issues a quarterly report prepared by the MOV Coordinator
that lists the status of the program testing efforts and MOV failures
occurring during the period covered .. The reports also indicate the root
cause for the failures and tracks the failures by item type since 1991.
The inspectors reviewed 323 deviation report (DR) summaries and their
associated corrective actions.
Fourteen DRs were selected for detailed
review.
The corrective action taken that included the work order and
the engineering evaluation were verified for adequacy and completion.
Nine examples of the 14 DRs examined in detail are as listed as follows:
1) DR S-94-0481 - The Maximum thrust appeared to be exceeded.
2) DR S-93-0977 - Review classified 24 MOVs to EQ and GL 89-10.
3) DR S-94-1078 - Thermal overloads were not sized and replaced.
4) DR S-93-0741
Inspect MOV's gears for fatigue cracking.
5) DR S-94-0496
There was no acceptance criteria for switch.
6) DR S-94-0374 - Motor leads have 260 V reading to ground.
7) DR S-94-0274
Water was in switch housing.
8) DR S-94-0635 - Breaker tripped motor when switch failed.
9) DR S-95-0609
High current indicated during testing.
These nine examples were presented to show that the licensee's program
had requirements for identifying failures, taking appropriate corrective
action, and trending the problems.
The inspectors concluded the
licensee's program in this area was satisfactory.
2.6
Schedule
By letter dated December 26, 1989, the licensee committed to meet the
recommendations and schedule of GL 89-10.
In a letter dated June 29,
1993, the licensee informed the NRC Staff that they were revising its
schedule commitments for Unit 1.
On August 19, 1993, the staff notified
the licensee that it would assess the licensee's justification for the
schedule extension during an inspection.
The factors for review listed
in the August 19, 1993, letter are similar to those that were
subsequently issued in Supplement 6 to GL89.-:-10 *. At. Surry, .the.
inspectors discussed the present schedule for completing the GL 89-10
programs with licensee personnel.
The licensee stated that the present
GL 89-10 completion schedules for its nuclear plants are the Fall of
1995 for Unit 1 (including schedule extension) and the Spring of 1995
for Unit 2.
For the GL 89-10 schedule extension, the factors listed in the
August 19, 1993, letter and the licensee's action are summarized below:
ACTION 1
STATUS 1
Establish the actual completion status of the GL 89-10
program for MOVs not yet set up under the program.
Design-basis reviews and calculations determining setpoints
are complete for rising stem and quarter-turn MOVs.
Static
diagnostic tests have been performed on rising-stem MOVs.
10
Differential pressure testing complete for 32 rising-stem
and 15 quarter-turn MOVs in Unit 1, and 21 rising-stem and
11 quarter-turn MOVs in Unit 2.
The licensee stated that
eight rising-stem and two quarter-turn MOVs remain to be
tested in Unit 2 at the next refueling outage.
ACTION 2
Establish the basis for confirming the operability for each
MOV not set up under the program by June 28, 1994.
STATUS 2
The inspectors reviewed the status of the licensee's GL 89-
10 program and the MOVs not set up under the GL 89-10
program.
The inspectors found the thrust output at the
present torque switch settings for those MOVs requiring a
schedule extension compare favorably with best available
data from plant and industry data. However, the inspectors
considered MOVs CH-1115E and 2350 will require further NRC
review of their capability based on best available data and
encouraged the licensee to address those MOVs on a priority
basis.
ACTION 3
Establish the schedule for completing MOV testing and
modifications.
STATUS 3
Differential pressure testing will be completed during the
next Unit 2 refueling outage. Modifications are being
considered for 1-SI-MOV-1842, 1-RS-1558, and 1-SI-1862A/B.
(Section 2.3)
ACTION 4
Provide the extent of completing MOV testing under dynamic
testing.
STATUS 4
See ACTION 1 status.
ACTION 5
Provide the extent that plant and industry data have been
used to establish the sizing and setting methodology.
STATUS 5.
With respect to the licensee's.overall MOV sizing and.switch
setting methodology, the licensee evaluates test data to
verify the assumptions in their methodology and, where the
data does not support the assumptions, the licensee revises
the switch setting requirements for the tested MOVs and
other applicable MOVs.
The licensee has prepared
documentation for the verification of design-basis
capability for non-tested MOVs that also cannot be grouped
with other MOVs.
Based on the inspectors' summary review of
the licensee's documentation, the inspectors considered that
some of the justifications for verifying design-basis
capability in lieu of dynamic testing will require further
NRC review as part of GL 89-10 closure.
ACTION 6
STATUS 6
ACTION 7
STATUS 7
11
Provide the maintenance and modification activities to
improve the performance of the MOVs.
The licensee has reset torque switches on GL 89-10 MOVs as
necessary. Eight actuators have been replaced to increase
their design margins.
Four MOVs have undergone gear changes
to increase their design margins. Also, see ACTION 3
status.
Establish justification for any grouping methods used.
The licensee has established a grouping methodology that, in
many respects, follows the provisions of Supplement 6 to GL 89-10.
The inspectors raised concerns with the licensee's
plan to test only one MOV for some groups containing two
MOVs.
The testing of only one MOV in a group does not
provide confidence that the performance of the tested MOV is
representative of the group.
The licensee will need to
justify the design-basis capability of the grouped MOVs not
differential pressure tested as part of GL 89-10 closure.
The inspectors raised concerns regarding the licensee's
grouping and testing of butterfly valves.
The licensee
presently plans to perform dynamic testing of butterfly
valves without diagnostics. The licensee is performing
static tests with limited diagnostics.
For example, the
licensee might monitor motor current and spring pack
deflection, but not torque, during a static test. The
licensee believes that its use of vendor test data,
surveillance testing of some butterfly valves under dynamic
conditions, and its evaluation of industry test data, will
be sufficient to justify initial and periodic design-basis
capability verification without additional diagnostic data.
The licensee will need to justify its butterfly valve
grouping and testing as part of GL 89-10 closure.
The inspectors concluded that the licensee satisfactorily addressed the*
factors listed in the August 19, 1993, letter for justifying the GL 89-
10 schedule extension for Surry 1.
2.7
Followup of Previous Inspection Findings
The inspectors reviewed the status of the 11 open findings identified
during the previous GL 89-10, Part 1, inspection conducted November 18-
22, 1991.
The findings and the results of the inspectors' review are
briefly described below:
1.
The process for consideration of flow in design-basis
testing and analysis was not adequately specified in the MOV
program .
12
The licensee developed a "Testing Basis & Results Document"
to address testing conditions including flow and to provide
analysis.after the testing was performed. (Section 2.1)
2.
The licensee used the Kalsi Study to justify overthrust
conditions.
The inspectors found the licensee's overthrust procedure to
be inconsistent with Limitorque Maintenance Update 92-1 for
visually inspecting an actuator following an overthrust or
overtorque condition.
The licensee stated that the
procedure would be reviewed and updated.
This will require
further NRC evaluation as part of GL 89-10 closure.
3.
The licensee plans to use MOV grouping.
(Section 2.6, Action Item 7)
4.
The valve factor assumptions were not conservative.
Initially, the licensee assumes a valve factor of 0.3 for
wedge gate and 0.2 for double disk gate valves in setting
the MOVs in its GL 89-10 program, except for Westinghouse
gate valves, which have a 0.55 valve factor assumption in
response to vendor guidance.
The licensee increases the
thrust predicted from the standard industry equation
(including dynamic thrust load, stem rejection load, and
packing load) by a 1.15 factor.
The licensee compares test
data at an apparent flow cutoff with the thrust requirement
prediction. The inspectors were concerned with the
selection of flow cutoff for certain tests and the overall
applicability of flow cutoff data between tested and non-
tested MOVs.
The inspectors did not identify any immediate
operability problems.
The licensee increases its thrust
requirement for all MOVs in a group when test data exceeds
the predicted value.
The licensee justification will
require further NR~ evaluation as part of GL 89-10 closure-
(Section 2.2 and 2.3)
5.
The valve stem friction coefficient was not conservative.
The licensee assumes a stem friction coefficient of 0.15 for
its MOVs.
The licensee does not have plant data to support
its stem friction coefficient assumption, but relies on EPRI
and Kalsi laboratory test data.
The inspectors were
concerned that the lack of specific plant data will be
insufficient to justify the stem friction coefficient in
light of information from other utilities that a 0.15 stem
friction coefficient cannot always be justified. The
licensee justification will require further NRC evaluation
as part of GL 89-10 closure.
(Section 2.2 and 2.3)
13
6.
The licensee did not have "as found" diagnostic testing
specified as a requirement after preventative maintenance.
The licensee plans to perform "as-found" MOV diagnostic
testing as part of its periodic verification of MOV
capability.
In Technical Report PE-0016 (Rev. 1, July
1994), the licensee describes periodic stati~ testing to
attempt to identify design-basis capability degradation.
The licensee does not provide justification for monitoring
dynamic performance degradation. The licensee will need to
address this issue as part of GL 89-10 closure.
7.
The documents and procedures in the GL 89-10 MOV Program
need updating.
The inspectors verified that the GL 89-10 documents and
procedures referenced in Technical Report No. PE-0016 (MOV
Program) had been revised and updated since the Part 1
inspection.
8.
The high ambient temperature effects on motor torque had not
been accounted for.
The inspectors verified the high temperature were accounted
for in calculations EE-0083 and EE-0501. (Section 2.1)
9.
Thermal overload resistance had not been used in the
electrical calculations.
The inspectors verified that thermal overload resistances
were used in the revised electrical calculations. (Section
2.1)
10.
A set screw failure caused the motor pinion to slide causing
2-CW-MOV-200D to fail a stroke test.
The.licensee.was .responding to.NRC Information- Notice 94-10
(February 4, 1994), "Failure of Motor-Operated Valve
Electric Power Train Due to Sheared or Dislodged Motor
Pinion Gear Key."
The licensee has not completed the
response. This item will be require further NRC review as
part of GL 89-10 closure.
11.
At the time of the Part 1 inspection there was minimal DP
testing completed
Since then, the licensee has completed dynamic tests of 53
rising-stem and 26 quarter-turn MOVs at Surry.
The
inspectors considered the large number of DP tested MOVs to
be acceptable .
- ..
14
2.8
Pressure Locking and Thermal Binding
The Office for Analysis and Evaluation of Operational Data (AEOD) has
completed a study of pressure locking and thermal binding of gate
valves.
AEOD concluded in their report that licensees have not taken
sufficient action to provide assurance that pressure locking and thermal
binding will not prevent a gate valve from performing its safety
function.
The NRC regulations require that licensees design safety-
related systems to provide assurance that those systems can perform
their safety functions.
In GL 89-10, the staff requested licensees to
review the design basis of their safety-related MOVs.
The licensee provided documentation of its evaluation of the potential
for pressure locking and thermal binding of gate valves as follows:
(1)
Report, Thermal Binding/Bonnet Pressurization of Gate Valves
October 2, 1991.
(2)
Memo, E. May to P. Boulden,
Response to Nuclear Licensing
Review Comments on the Pressure Locking/Thermal Binding of
Gate Valves, Type 1 Reports, North Anna and Surry Power
Stations, NP 2196/NP 5479, September 11, 1992.
(3)
Memo, E. May to P. Boulden, Response to Operating Experience
Review Group Comments on the Pressure Locking/Thermal
Binding of Gate Valves, Type 1 Reports, North Anna and Surry
Power Stations, NP 2196/NP 5479, dated November 9, 1992.
The inspectors found that the Reference (1) report indicated that a
review of all safety related gate valves had been performed and
concluded that none of the valves had a significant probability of
thermal binding or pressure locking. References (2) and (3) described
concerns and related responses identified from internal reviews of NRC
Information Notice 92-26 and Reference (1).
The responses provided
additional support for the conclusion of Reference (1). These licensee
reports are two to three years old and do not reflect recent information
and-concerns regarding this issue. The. l.icensee-will be expected to
show additional progress in this area before GL 89-10 closure.
The licensee was informed that the NRC plans to issue a Generic Letter
to address continued concerns regarding pressure locking/thermal
binding.
2.9
Quality Assurance {QA) Involvement
The inspectors evaluated the licensee's implementation of QA for
GL 89-10 activities. The inspectors reviewed QA and quality control
(QC) entries in the QA Tracking and Trending System.
QA reports
(Maintenance Audit 92-17, four quarterly MOV assessment reports in 1989
and 1990); the 1992 and 1993 corporate annual MOV assessment reports;
the last eight quarterly status reports for MOVs from System
Engineering; and the last four maintenance (MOV coordinator} quarterly
. j
'
15
reports.
QA's initial reports identified issues that were resolved;
however, QA recent involvement in the MOV program has been minimal.
recent involvement in MOV activities was limited to observing testing
and followup of the DRs discussed in Section 2.5.
The main QA efforts are with the System Engineers and the MOV
Coordinator in the Maintenance Department.* The System Engineers provide
quarterly reports of both past and current MOV issues. The MOV
Coordinator provides quarterly reports that track and trend each MOV
issue, concern, failure, and the corrective action.
The corporate
annual assessments review the program for adequacy and the need for
improvement.
The inspectors concluded the licensee's efforts in
providing QA for the MOV program are appropriate.
2.10 Walkdown
A walkdown inspection of selected MOVs was conducted by the inspectors
to observe the installed yoke sensors and the condition of the valve
stems.
In general, the valves were found in good condition. The valve
stems were satisfactorily lubricated. It was noted that valves other
than MOVs (air-operated and manual) were well-maintained, as indicated
by proper stem lubrication and cleanliness. The yoke sensors that had
been installed for diagnostic testing were examined to determine their
general condition including the installed location and wiring
connections.
The inspectors concluded the condition of the MOVs
examined was satisfactory.
2.11
GL 89-10 Program Closure
For program closure, some of the principal areas that the NRC will
evaluate include the licensee's justification and appropriate
information:
that thrust requirements are established for MOVs that are
not dynamically tested to support design basis capability;
that the VF and SFC used.are.specifi~to the valves and the.
plant;
that plans for periodic verification of MOV design~basis
- capability are established;*
that the assumed VF and SFC used in thrust calculations
should be demonstrated appropriate for the MOVs not
dynamically tested;
that the torque switch settings ensure that the torque
rating is not exceeded in support of the 2.25 torque switch
settings;
that progress in addressing pressure locking and thermal
binding of gate valves is made;
... . .
- r
16
that adequate capability of MOVs with motor brakes exists.
3.
EXIT INTERVIEW
The inspection scope and results were summarized on April 15, 1994, with
those persons indicated in paragraph 1.
The inspectors described the
areas inspected and discussed in detail the inspection results listed
below.
Proprietary information is not contained in this report.
Dissenting comments were not received from the licensee.
One unresolved item (URI) concerning the misuse of "stall torque" and
"stall efficiency" in thrust calculations was identified. After staff
review this URI was changed to a non-cited violation, NCV-50-280/94-18-
01, MDV Design Thrust Calculation Error.
The licensee was informed by
telecon on August 25, 1994.
4.
ACRONYMS AND INITIALISMS
cs
DR
DP
EE
FT-LB
GL
INEL
ME
NRC
PSID
SFC
Alternating Current
Office for Analysis & Evaluation of Operational Data
Charging
Charging System
Control Switch Trip
Design Basis Document
Deviation Report
Direct Current
Differential Pressure
Electrical Engineering
Electric Power Research Institute
Engineering Work Request
Final Safety Analysis Report
Foot pounds (torque)
Generic Letter
Idaho National En-gineering Laboratory
Mechanical Engineering
Motor Operated Valve
Nuclear Regulatory Commission
Office of Nuclear Reactor Regulation
Process/Piping and Instrumentation Diagram
Pounds Per Square Inch Differential
Quality Assurance
Quality Control
Rate of Loading
Stem Friction Coefficient
Safety Injection
I*
f ,'!
f
TBRD
TI
V
VOTES
17
Testing Basis & Review Document
Temporary Instruction
Thermal Overload
Unresolved Item
Volts
Valve Factor
Valve Operation Test and Evaluation System
e
APPENDIX A.
SURRY POWER STATION GATE VALVE DATA
Diagnostics: VOTES
VALVE
VALVE
TEST
%
DYNAMIC
STEM
%
NO.
TYPE
CONDIDONS
DESIGN
VALVE
FRICTION
LOAD'*
(psid)
BASIS
FACTOR'*
COEFFICIBNT
SENSITIVE
BEHAVIOR
Ope
Clos
Open
Clos
Ope
Close
Stati
Dynamic
n
e
e
n
C
1-SI-
8" Aloyco
163
163
82
82
N/C3
N/C
N/C
N/C
2.0
MOV-
300#
1863A
Solid Wedge
Gate
1-FW-
6" Crane
1360
1360
94
94
NIC
N/C
N/C
N/C
Limit
MOV-
600#
Closed
160A
Flex Wedge
Gate
2-SI-
4" Darling
2660
2660
100
100
NIC
N/C
N/C
N/C
-3.4
MOV-
1500#
2842
Double Disc
Gate
1-CH-
3" Velan
2675
2675
97
'97
N/C
N/C
N/C
N/C
-2.6
MOV-
1500#
1286B
Flex Wedge
Gate
1* Valve factor was calculated using orifice diameter.
2* A negative number indicates that the thrust observed at CST during the dynamic test was greater than the thrust observed at CST during the static
test.
3* "N/C" = Not Calculated. Virginia Power does not routinely back calculate valve factor. Virginia Power assumes a stem friction coefficient of
0.15.