IR 05000275/1993019
| ML16342A259 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/17/1993 |
| From: | Ang W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML16342A258 | List: |
| References | |
| 50-275-93-19, 50-323-93-19, GL-89-10, NUDOCS 9309290175 | |
| Download: ML16342A259 (46) | |
Text
ENCLOSURE U.S.
NUCLEAR REGULATORY COMMISSION
REGION V
Report No.:
93-19 Docket Nos.:
50-275/323 License Nos.:
DPR-80/82 Licensee:
Pacific Gas and Electric Company Facility Name:
Diablo Canyon Unit 1/2 Inspection Conducted:
Duly 19 - 23, 1993 Inspectors:
C. Myers, Reactor Inspector, Region V
M. Runyan, Reactor Inspector, Region IV Accompanying Personnel:
M. Holbrook, Consultant, EGSG Idaho-INEL Approved:
W
. Ang, Chief E
>neer)ng Section Division of Reactor Safety, Region V
Date Ins ection Summ"~r Ins ection durin the eriod of Jul 19-23 1993 Re ort No. 93-19 Areas Ins ected:
Special, announced inspection of the implementation of the licensee's program to meet commitments to Generic Letter (GL) 89-10,
"Safety-Related Motor-Operated Valve Testing and Surveillance,"
and followup of previous open items.
Part 2 of Temporary Instruction 2515/109 and Inspection Module 92701 were used as guidance during the inspection.
Results:
General Conclusions and S ecific Findin s:
~ The licensee's program was generally effective in establishing assurance of design basis capability for the sampled MOVs.
~ The licensee was implementing a program consistent with their commitments to Generic Letter 89-10.
~
Ei ror allowances were inappropriately incorporated in setpoint calculations.
~ Setpoint calculations did not conservatively account for some sources of error.
9309290175 930817 PDR ADOCK 05000275 Q
0
~ Test data was not fed back into setpoint calculations.
~ Corrective actions for a test failure of NOV 2-LVC-109 were inadequate.
~
~ Lack of torque measurement was a program weakness.
~ Inadequate documentation of signature anomalies was a program weakne'ss.
~ Lack of justification for testing at less than design basis flow was a
weakness.
a
~ Force sensor calibration was not adequately controlled.
Summar of 0 en Items New Open Items 93-19-01 Unresolved:
Open 93-19-02 Followup:
Open 93-19-03 Followup:
Open Inadequate Corrective Actions for 2-LCV-109 (p 17)
Implementation of Corrective Actions for Pressure Locking Concerns (p.3)
Evaluation of Diagnosti.c Signature for 2-FCV-37 93-19-04 Followup: Open-I Use of Valve Specific Values in Calculations (p. 10)
93-19-05 93-19-06 Followup:
Open Followup:
Open Review of Previous Test Data (p. 10)
Review of Limit Seated NOV Torque Switch Setting (p.7)
Previous Open Items 90-16-01 Followup: Closed 91-39-01 Followup: Closed 91-39-02 Followup:
Open 91-39-03 Fol lowup:
Open 93-03-03 Followup:
Open NOV Spring Pack Deficiencies (p.19)
NOV Switch Sizing (p. 19)
Periodic Verification (p.20)
NOV Trending (p.20)
Genetic Concern for Valve Bonnet Leakoff Flow
'p 20)
DETAILS 1.0 PERSONS CONTACTED Licensee Personnel
- A. Barchas, Engineering Coordinator, Nuclear Engineering Services (NES)
- D. Bauer, Senior Electrical Engineer, Electrical Maintenance S.
Chon, Engineer, Onsite Project Engineering Group (OPEG)
- W. Crockett, Manager, Technical Support
- M. Davido, Senior Engineer, NES
- B. Giffin, Manager, Maintenance Services
- R. Goel, Program Manager, NES
- K. Hubbard,'ngineer, Regulatory Compliance
- W. McDaniel, Consultant, NES
- D. Miklush, Manager, Operations Services
- S. Ortore, Director, Electrical Maintenance
- J. Portney, Senior Engineer, System Engineering
- R. Powers, Manager, Nuclear guality Services
- J. Rappa, Foreman, Electrical Maintenance
- J. Shoulders, Director, NES
- J. Townsend, Vice President and P'lant Manager
- A. Toy, Engineer, Predictive Maintenance
"M., Williamson, Engineer, Electrical Maintenance NRC Personnel
- F. Gee, Resident Inspector In addition to the personnel listed above, the inspectors contacted other personnel during the inspection.
- Denotes personnel that attended the exit meeting.
2.0 GENERIC LETTER GL 89-10 4SAFETY-RELATED MOTOR-OPERATED VALVE TESTING AND SURVEILLANCE" (TI 2515/109)
On Dune 28, 1989, the NRC issued Generic Letter (GL) 89-10 which requested licensees to establish a program to ensure that switch settings for safety-related motor-operated valves (MOVs) were selected, set, and maintained properly.
Five supplements to the generic letter have been subsequently issued.
NRC inspections of licensee actions implementing commitments to GL 89-10 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."
Instruction TI 2515/109 is divided into Part 1,
"Program Review," and Part 2, "Verification of Program Implementation."
The TI 2515/109 Part 1 program review at Diablo Canyon was documented in NRC Inspection Report 91-39.
The current inspection was conducted using Part 2 of TI 2515/10 '
The inspection consisted of a detailed review of the licensee's documentation of their GL89-10 activities for selected NOVs.
The selection of sample NOYs was based on an information matrix provided by.the licensee.
The selection was biased toward NOVs that appeared to have marginal actuator capacity and thrust settings compared to calculated requirements.
The sampled NOVs.
-included a variety of valve and actuator sizes.
The selected NOVs included examples of testing under various differential pressure conditions.
For each NOY selected, the inspectors reviewed the design basis calculation of
, design flow, temperature, and the maximum expected differential pressure (NEDP), the sizing and switch setting calculation, the diagnostic test data package, and the diagnostic traces using VOTES (Valve Operator Test and Evaluation System, Liberty Technology Corporation) Version 2.3 software.
The following NOVs were selected for review:
1-FCV-95 Auxiliary Feedwater (AFW) Turbine Steam Inlet 2-FCV-37 AFW Turbine Steam Supply 2-8105 Charging Pump Mini-Flow 2-9003B Residual Heat Removal (RHR)
Pump to Spray Header 2-8801A Safety Injection (SI)
Pump Discharge 1-8821A Charging Injection 2-LCV-109 AFW Pump Discharge/
SG Level Control 2-9001B Spray Pump Discharge Isolation 2-8923A-X SI Pump Suction 1-8803B Charging Injection,Valve The selected NOYs include eight gate valves and two globe valves, all with Limitorque actuators.
No butterfly valves were selected.
The sample NOVs were configured as shown below:
Actuator Closure Control Valve Size inches and Vendor 1-FCY-95 2-FCY-37 2-8105 2-9003B 2-8801A 1-8821A 2-LCV-109 2-9001B 2-8923A-X 1-8803B SNB-00 SNB-00 SNB-00 SNB-1 SNB-0 SNB-00 SNB-000 SB-00 SMB-00 SMB-0 Limit Seated Torque Seated Torque Seated Torque Seated Torque Seated Torque Seated Torque Seated Torque Seated Torque Seated Limit Seated 4" Anchor Darling 4" Velan 2" Velan 8" Anchor Darling 4" Velan 4" Velan 2" Consolidated Controls Inc.(CCI)
8" Anchor Darling 6" Aloyco/Walworth 4" Anchor Darling A summary of the test data for the sampled valves is provided in Attachment l.
The inspectors concluded that the implementation of licensee's NOV program was adequate for the sampled NOVs.
For the most part, the program appeared to implement the licensee's commitments to the generic letter.
One unresolved item was identified in Paragraph 2.. 1 Desi n-Basis Reviews The inspectors reviewed licensee calculation D-031, "Actuator Sizing and Setpoint Calculation of Rising Stem Valves with Limitorque Actuators",
Revision 12, dated April 17, 1993.
This calculation documented the maximum expected differential pressure (NEDP, alternately referred to as the design-basis differential pressure),
design flow conditions, design temperature, and other design parameters for each of the NOVs selected for review.
The calculations appeared to acceptably address these design basis parameters for the selected NOVs.
2. I.a Pressure Locking and Thermal Binding The inspectors reviewed the licensee's evaluation of the potential for pressure locking and thermal binding of gate valves.
The inspectors reviewed Nuclear Engineering and Construction Services (NECS) memorandum to Nuclear Operations Support (NOS), "Pressure Locking of Gate Valves,"'ated 10/6/92.
The licensee identified 26 NOVs in each unit which met theit review screening criteria for valves susceptible to pressure locking or thermal binding.
As a
result of their review, the licensee=identified six susceptible valves:
1/2-8703, 2-8801A/B, 2-8803A/B.
The licensee review recommended three options as corrective actions, for each of the valves:
1) Drill a hole in the high pressure side of the disk.
2) Install a bonnet leakoff line and block valve.
3) Install a bonnet relief valve and discharge line.
According to the licensee, these modifications were sche'duled to be made during the next refueling outage in the each Unit (1R6/2R6) in 1994.
The inspector s found the licensee's evaluation to be adequate.
Review of the implementation of licensee corrective actions will be an open item. {93-19-2:OPEN)
The inspectors reviewed nonconformance report (NCR) PDC0-92-TN-N38, dated August 20, 1992, which identified a potential generic concern affecting the charging injection valves to the RCS hot leg, SI-8802A/B.
The double disk gate valves had been supplied by Mestinghouse with a bonnet leakoff line and block valve to preclude pressure locking by venting the bonnet to the high pressure
{RCS) side.
The valves are normally closed with the leakoff block valves open and are required'to open for hot leg injection.
During cold leg injection, the valves are closed.
However, some leakage flow exists past the upstream disk into the bonnet and out the bonnet vent line.
The licensee identified that the leakage flow had previously not been recognized and could result in inadequate cold leg injection flow and safety injection pump'runout.
Immediate licensee corrective actions were taken to throttle the leakoff line block valves to 1/4 turn open.
The licensee identified the unexpected leakoff flow to be up to 70 gpm during GL89-10 testing of SI-8802A/B.
The inspectors
found the initial licensee corrective actions for the NCR to be adequate.
The licensee was addressing the potential generic concern for unaccounted bypass flow in double disk gate valves with bonnet leakoff lines through Westinghouse.
This issue had been previously identified as an open item and will remain open pending review of the licensee's followup with Westinghouse (93-03-03:OPEN).
2.2-NOV Sizin and Switch Settin 2.2.a Calculation Nethod The inspectors reviewed Nuclear Engineering Services procedure No. ICE-12,
"Preparation of Notor-Operated Valve Sizing and Switch Setpoint Calculations,"
Rev. 4, dated Narch 15, 1993, and design calculation D-031, "Actuator Sizing and Setpoint Calculation of Rising Stem Valves with Limitorque Operators,"
Rev.
12, dated April 17, 1993.
These calculations documented the licensee's method.for determination of thrust and torque requirements for the sampled NOVs.
The inspectors noted the following features of the licensee's method.
1.
For valves required to operate at differential pressure conditions less than 1000 psid, the licensee typically assumed a valve factor of 0.30 for flex-wedge gate valves and 0.25 for double disk valves.
For operation above 1000 psid, the design valve factor was increased to 0.40
- for wedge gate valves and 0.30 for double disk valves.
2.
In calculating actuator output thrust capability, the licensee typically assumed a stem friction coefficient of 0.20.
3.
A thrust margin of 158 was incorporated in the setpoint calculations to address possible NOY load sensitive behavior (also known as "rate of loading" ).
The thrust margin was a percentage in excess of the minimum calculated required thrust.
4.
Ninimum thrust requirements accounted for diagnostic equipment inaccuracy, torque switch repeatability, stem lubricant.degradation, and seismic concerns.
5.
The licensee had included a
7N thrust margin in the setpoint calculation to account for stem lubrication degradation.
The licensee stated that this margin may be later adjusted based on future test results and industry research.
The licensee employed both torque and limit seating as motor control logic depending of the valve type.
Conventional torque seating, in which the torque switch activates at a preset actuator output torque to stop the motor during valve seating, was the predominant method fot flex wedge gate valve and all globe valves.
Limit seating, in which a position switch opens near the end of the valve stroke to stop the motor during valve seating, was used for sealing split wedge double disk gate valves after flow cutoff.
Using this control
logic, the torque switch remained in series with the limit switch to act as over load protection.
According to the licensee, the closing logic on several torque seated gate valve NOVs will be changed during an upcoming outage to "bypass seating."
The licensee defined bypass seating as torque seating after flow cutoff.
Mith this control logic, the torque switch would be bypassed for the majority of the closing stroke until the point of flow cutoff.
After flow cutoff, the torque switch would control the wedging force and the final seating thrust.
Using this control logic, the licensee assumed a valve factor of 0.6 when calculating actuator capability.
However, the torque switch setting controlling the final seating thrust would be based on a valve factor of 0.3.
The inspectors noted that the licensee planned to use bypass seating on 28/ of the. gate valves within their program to minimize high inertia thrust resulting from closure under static conditions.
The inspectors noted that the limiter plate did not provide protection against overtorque since the close torque switch will be bypassed until flow cutoff.
Mithout measurement of torque during diagnostic testing, the inspectors were concerned that actuator output torque could not be assured to remain within manufacturer ratings.
This concern is further discussed in Paragraph 2.3.f.
2.2.b.
Diagnostic System Inaccuracy The inspectors found the licensee's consideration of VOTES diagnostic equipment inaccur acies and other 'instrument uncertainties as a strength in their program.
The post test evaluation sheets clearly identified when torque correction factors needed to be applied and provided the methods to be used to modify diagnostic equipment inaccuracies when measured values were outside the calibration range.
The inspectors determined that further appropriate adjustments were made if the VOTES calibrator was mounted on a stem located in a high temperature environment as recommended in VOTES Part 21 notification dated October 2, 1992.
Pressure and flow instrumentation used during the test was also identified by the licensee.
Appropriate adjustments were made to account for the inaccuracies of the instruments.
2.2.c Setpoint Error Adjustment The inspectors observed that the licensee's ICE-12 calculation applied error allowances in determining minimum and maximum tht ust setpoints.
The procedure calculated a combined uncertainty (which included diagnostic system inaccuracy, rate of loading, stem lubrication degradation, torque switch repeatability, and seismic loads).
The procedure added the combined uncertainty as a percentage to the calculated minimum required thrust (NRT)
and subtracted it from the calculated maximum allowable thrust.
With, the exception of seismic loads, the inspectors noted that the individual sources of uncertainty were applicable to measured values rather than
'calculated value Ri
The licensee stated that the ICE-12 procedure would be revised.
The licensee also stated they will change their error analysis to combine diagnostic system error and torque switch repeatability in a square-root-sum-of-the-squares (SRSS) computation.
During the inspection, the licensee performed a preliminary evaluation of the effect that its new setpoint methodology would have on operability of NOVs in the GL 89-10 program.
The licensee concluded that no operability issue existed.
The inspectors concluded that the licensee actions were adequate.
The licensee is expected to follow the preliminary oper ability evaluation with a detailed valve-by-valve assessment of its new applicable setpoints and resultant thrust margins.
2;2.d.
Load Sensitive Behavior The inspectors observed that the calculated minimum required setpoint included a
15% thrust margin to account for load sensitive behavior (also known as
"rate of loading" ) for those NOVs that were torque seated.
The inspectors noted that the licensee did not include margin for load sensitive behavior for limit seated valves because, the torque switch was not utilized for primary motor control.
The inspectors'noted that the licensee's limit seating motor control logic incorporated the torque switch in series with the limit switch rather than bypassing the torque switch entirely.
Altho'ugh not used for primary motor control, the licensee adjusted the torque switch to the maximum setting allowed by the limiter plate to act as back up protection in case of a failure of the limit switch.
With this configuration, the torque switch remained enabled during the entire closing stroke.
Since the torque switch was not bypassed, the inspectors noted that it could actuate prematurely under dynamic conditions due to load sensitive behavior thereby limiting the available actuator capability.
The inspectors noted that marginal capacity NOVs may require full actuator capability for design basis operation.
The inspectors concluded that the licensee had not adequately justified their treatment of load sensitive behavior for the torque switch setpoints of limit seated NOYs.
The inspectors did not identify any concerns due to the torque switch setting for the two limit seated valves which were selected for review.
The licensee's position was that their testing would identify any inadequacies in the backup torque switch setting.
The inspector is position for HOVs tested at worst case design basis condi,tions but pointed out that all HOVs in the licensee's program would not be tested under those conditions.
Further evaluation of the licensee's treatment of load sensitive behavior in the torque switch settings of limit seated valves will be an inspector followup item (93-19-06:
OPEN).
2.2.e.
Torque Switch Repeatability The inspectors noted that the licensee's minimum thrust setpoint did not account for torque switch repeatability greater than 5%.
Limitorque maintenance Update 92-2 had identified torque switch repeatability up to 10%
in certain cases.
Further, the licensee did not include any consideration of
torque switch repeatability when adjusting the upper window thrust limit for diagnostic equipment uncertainty.
Licensee personnel stated that they were currently revising their thrust calculations to account for the repeatability values contained in Limitorque Naintenance Update 92-2 and had not identified any operability concerns based on an initial screening.
Further, the licensee determined that no cases existed where greater than 6%
uncertainty would apply to the upper allowable thrust limit.
The licensee considered that the small error for torque switch repeatability, combined through a square-root-of-the-sum-of-the-squares method with the diagnostic equipment inaccuracy, would have minimal effect on the existing upper allowable thrust setpoint.
However, the licensee will revise their ICE-12 procedure to include consideration of the appropriate torque switch repeatability by August 31, 1993.
The licensee reviewed existing torque switch settings for all NOVs in their GL89-10 program and determined that they were not affected by the planned adjustment to the setpoint.
The inspectors found the proposed licensee actions to be adequate.
2.2.f.
Open Torque Switch Bypass Setting The inspectors noted that the acceptance criteria used to evaluate the adjustment of the open torque switch bypass switch was potentially nonconservative.
In evaluating the test data, Pr ocedure ICE-12, Revision 4, Figure 8, Section 6. 12 asked the question
"Does maximum pullout force (09)
or force right after disk pullout (010) occur within the torque switch bypass region7" If the answer to this question was "yes," no further action was required.
The inspectors pointed out that a significant amount of thrust to overcome opening differential pressure remains after the peak thrust which may extend past the bypass switch setting.
If the open torque switch was actuated by the thrust required to overcome the differential pressure e, the valve stroke would stop prematurely when the bypass switch position was reached.
Furthermore, an open stroke differential pressure test, conducted at only a small percentage of the design basis differential pressure and flow, may reach peak opening thrust (010) much sooner in the stroke than would occur under full design basis conditions.
The licensee acknowledged the inspectors'oncerns and committed to revise
'heir evaluati'on criteria to assure an adequate bypass switch setting past the point of peak differential pressure thrust.
The inspectors did not identify any operabil.ity concerns related to this issue in the evaluation of the
NOVs reviewed during this inspection.
The inspectors found the licensee proposed actions to be adequate.
2.2.g.
AC Notor Torque Derating due to High Temperature The inspectors reviewed the licensee's response to the Limitorque 10 CFR Part 21 letter dated Nay 13, 1993 concerning the effect of ambient temperature on the starting torque of AC'motors.
The licensee had evaluated the impact of the Part 21 report on all GL 89-10 NOVs.
The inspectors found the licensee's response to the Part 21 notification to be prompt and comprehensiv.2.h.
Use of Neasured Valve Packing Load The licensee used measured valve data from dynamic testing to predict design basis capability.
However, the inspectors found that the license was not incorporating measured valve packing loads in their ICE-12 calculations.
The licensee performed their test data analysis and calculations according to their procedure ICE-12.
In calculating the "projected minimum required thrust at design basis delta P",
Figure 8, step 7.4 of ICE-12 specified the use of the maximum allowable stem packing friction as determined in calculation 0-039 or J-41.
The procedure did not require the use of measured packing loads if they exceeded the calculated values.
The inspectors noted one example where the use of the calculated packing load as an input for the determination of projected minimum required thrust was nonconservative.
The inspectors reviewed the static diagnostic test of NOV 2-8801A.
The inspectors observed that the measured average running force in the closing direction (which in a static test is equivalent to the packing load)
was 2418 pounds force (lbf).
This actual packing load exceeded the maximum calculated value of 2187 lbf used in the ICE-12 calculation.
This deficiency did not impact operability since NOV 2-8801A had sufficient margin to account for the observed packing friction.
However, the inspectors were concerned because other NOVs in the GL 89-10 program had been evaluated using the same ICE-12 procedure.
The licensee acknowledged the inspectors'oncern and stated that ICE-12 would be revised to require the use of either the calculated or measured packing load, whichever is greater.
The licensee committed to review all previous NOV test data using the revised procedure by October 31, 1993.
The inspectors found the licensee's proposed actions to be adequate.
2.2.i.
Lack of Testing at Design Basis Flow Rates The inspectors reviewed a summary of all GL89-10 testing performed by the licensee and noted that a majority of the differential pressure tests did not achieve maximum expected, flow (NEF) conditions.
Further, the percentage of NEF attained during testing was sometimes much less than the percentage of the maximum expected differential pressure (NEDP).
For example, NOV 2-8801A was tested at 500%
NEDP but only 89% NEF.
NOY 2-8923A was tested at 70% NEDP but only 12% NEF.
Since the licensee's program permitted a "downward" extrapolation of required thrust in cases where the test differential pressure exceeds the design basis differential pressure, the inspectors were concerned that the licensee's evaluation of NOVs that were tested under low flow conditions may not be conservative.
The inspectors observed that the critical variable in assessing the accuracy of a design basis simulation is the amount of flow that passes through the valve at the point where required thrust reaches a maximum (typically near flow cutoff in a closing stroke).
The licensee did not,include a consideration of flow rate in the test acceptance criteria.
The inspectors emphasized that the licensee should justify all testing performed at less than design basis differential pressure and flo The licensee stated that flow effects were not considered in their calculations.
The licensee acknowledged the inspectors'oncern and committed to established adequate justification for their treatment of flow effects.
The inspectors found the licensee proposed actions to be adequate.
2.3.
Testin and Data Anal sis The licensee used the VOTES system as its primary diagnostic system.
In certain cases with limited access, a stem mounted Teledyne force sensor (ASS)
is used to measure thrust in place of the yoke mounted VOTES force sensor.
A previous load cell method was still used in parallel with the VOTES system for setting the torque switches.
According to the licensee, the load cell method was being phased out of use as the licensee's confidence in the VOTES system increases.
The inspectors did not review the licensee's load cell method or data.
The inspectors noted the licensee ICE-12 procedure required that the Engineering evaluation of NOV diagnostic signature data from dynamic testing be completed prior to returning the NOV to service in an operational mode in which the NOV is required to be operable.
2.3.a.
Design-Basis Capability The inspectors reviewed the licensee's basis for determining design basis capability for the valves listed in Attachment 1.
For each valve, the inspectors reviewed the static test results, dynamic test results and the licensee's ICE-12 data evaluation, Section 6.0, "Evaluation of Rising Stem NOV Differential pressure Test Results,"
and Figure 8, "Rising Stem NOV Test Evaluation Sheet" of ICE-12.
The inspectors reviewed the selected dynamic test data using the industry standard equation, mean valve seat diameter, and the dynamic test conditions.
This review indicated gate valve factors up to 0.47 and globe valve factors of 1.09 (see Attachment 1).
Load sensitive behavior was observed to reduce the thrust at torque switch trip by up to 32A.
Based on this review, it did not appear that the licensee's valve factor assumption of 0.4 for gate valves was always bounding.
However, no operability concerns were identified due to adequate excess margin.
To determine design basis capability from testing at less than design basis conditions, the licensee linearly extrapolates the measured thrust necessary to overcome differential pressure from test conditions to design basis conditions.
The licensee conducted several multi-point dynamic tests in an effort to develop a justification for their linear extrapolation method.
The licensee planned to justify its method of extrapolation within their schedule for the completion of their GL 89-10 program.
ICE-12, Figure 8, "Rising Stem NOV Test Evaluation Sheet,"
Rev.
3 did not include an extrapo'lation of the peak opening thrust to design basis conditions.
A later Revision 4 to the evaluation sheet did incorporate this
extrapolation.
However, the licensee had not yet reviewed the previous test data using the Revision 4 evaluation criteria.
The licensee committed to review previous data using the Revision 4 criteria by October 30, 1993.
This issue will be a followup item pending completion of the licensee's review of the previous test data.
(93-19-05:Open)
The licensee designated the measured thrust at flow isolation (Votes mark C)0) as the force required to overcome differential pressure (dP).
The licensee, extrapolated this thrust to establish the required torque switch setpoint to assure design basis capability.
The inspectors noted that the licensee analyst's marking of CIO was sometimes arbitrary.
Typically, a plateau on the thrust trace caused by the valve disk sliding on the seating surface provides the highest level of confidence that all bypass flow has been isolated.
Mithout an identifiable plateau, the point of flow isolation is often ambiguous.
Therefore, in designating the thrust required to overcome dP, the conservative practice recommended by the diagnostic equipment vendor was to consider the maximum thrust present between CIO and hard seat contact (Votes mark - CII).
The licensee acknowledged the inspectors'oncern and committed to review and revise their test data analysis technique as necessary to conservatively identify CIO for extrapolation purposes.
The inspectors found the licensee proposed actions to be adequate.
The inspectors noted that Revision 4 of Figure 8, "Rising Stem MOV Test Evaluation Sheet,"
did not include an evaluation of load sensitive behavior.
Licensee personnel stated that a program had been initiated to determine"if their base 158 assumption would be appropriate for those valves that will not be dynamically tested.
The inspectors noted that, once identified during testing, a higher than assumed value for load sensitive behavior should be incorporated into the thrust calculation in lieu of the original 15%
assumption.
This would be necessary to prevent inadvertently setting the torque switch too low during a future maintenance activity.
Licensee personnel stated that a revision of their test evaluation procedures currently under review will include a determination of load sensitive behavior and will require a revision of the minimum required thrust setpoint, if necessary.
Further, the licensee committed to conduct a similar review of existing test data by October 30, 1993.
Review of the licensee s evaluation of existing test data using the revised procedures will be an inspector followup item (93-19-04:
Open).
The inspectors noted that Step 7.1 of Figure 8, "Rising Stem MOV Test Evaluation Sheet, Rev. 4, contained a arithmetic sign error in the diagnostic error adjustment formula used in the determination of the corrected closing differential pressure force term.
For each NOY reviewed by the inspectors, this error had been recognized and corrected on a case by case basis by the licensee reviewer.
However, the procedure had not been revised to correct the error.
The inspectors found the same error persisting in a draft revision.
The licensee acknowledged the typographical error and stated that it would be corrected in Rev.
5.
The inspectors considered the licensee action to be adequate.
2.3.b.
Lack of Full Valve Closure
ll The inspectors reviewed three diagnostic signatures for NOV 2-8801A.
All the traces were obtained from testing at differential pressures (dP) in excess of the maximum design basis dP.
The inspectors noted that none of the traces associated with the closing strokes showed evidence of seat contact to indicate that the valve had fully closed.
The licensee had previously recognized this apparent failure to fully close during their review of the test data.
Despite the lack of evidence of valve closure in the signatures, the licensee had determined that the data met the test acceptance criteria.
The licensee's conclusion was based on the following:
(1) An engineer stationed at the NOV during the test heard the flow noises stop indicating flow cutoff, and (2) The test differential pressures of 2179, 2349, and 2545 psid so substantially exceeded the design basis differential pressure of 500 psid that seat contact under design basis conditions could be inferred.
The inspectors concluded that the demonstration of design basis capability for MOY 2-8801A was only marginally acceptable because of the lack of evidence of closure.
An additional weakness in the testing of NOV 2-880IA is discussed in Paragraph 2.2.i.
2.3.c.
Deficiencies in Diagnostic Signature Event Identification Evaluation of diagnostic signatures using the VOTES 3.2 software requires that an analyst identify specific standard events occurring during the operation of the NOV.
The selection of each event mark requires evaluation and cr oss-checking several parameters.
After the event is marked by the analyst, all coincident data at the time of the event is automatically selected and analyzed by the computer.
The skill of the analyst in correctly identifying events can significantly affect the accuracy of the test data.
The inspectors observed the following instances where the licensee had placed several event marks in positions that were either imprecise or nonconservative compared to the diagnostic system vendor recommendations.
1.
The zero mark (C3) on the trace for NOV 2-LCV-109 (test ¹2) was placed on the plateau preceding the opening running load.
Cross-checked against the power factor plot, the correct zero point appeared to be have been approximately 200 pounds lower in the force trace.
2.
On test ¹4 of NOV 2-8801A, the marks for flow cutoff (C10)
and seat contact (Cll) were placed nonconservatively in a portion of the thrust trace that showed no inflection or change in slope.
3.
On test ¹2 of NOY 2-8801A, the Cll mark for seat contact was improperly placed prior to the C10 mark for flow cutof.
Flow cutoff (C10) for test
$ 1 on NOV 2-8923 was marked at a point of no recognizable deflection on any of the available diagnostic traces and appeared to be nonconservative.
5.
Flow cutoff (C10) was not readily apparent on test 410 for NOV 2-FCV-37A.
In this case, the licensee had used a slight power factor indication to determine the point of flow cutoff.
This appeared to be nonconservative based on the shape of the thrust trace which showed increasing thrust up to the point of seat contact (Cll).
In light of considerable uncertainty in the exact location of this significant event, the licensee did not appear to use the conservative approach of marking flow cutoff (C10) at or near seat contact (Cll).
The inspectors concluded that, in cases of uncertain event occurrence, the licensee did not appear to conservatively mark the flow cutoff event.
This event was significant in the licensee's diagnostic signature analysis of test data because the measured thrust at the event was used for predicting design basis capability.
Due to adequate existing excess margin, none of the errors or nonconservative event markings observed by the inspectors affected the operability of the sampled NOVs with the potential exception of NOV 2-FCV-37, as discussed in Paragraph 2.3.d.
The licensee acknowledged the inspectors'oncern for the use of appropriately conservative values when analyzing diagnostic signatures.
This concern is further discussed in Paragraph 2.3.e.
2.3.d.
Improper Identification of Zero The inspectors reviewed of the licensee's ICE-12 evaluation of dynamic test data for NOV 2-FCV-37.
The inspectors found that the licensee's placement of the zero thrust mark appeared questionable and nonconservative.
Due to the marginal excess capability of this valve, the inspectors were concerned that the torque switch was not set high enough to deliver the thrust required to close the valve under design basis conditions.
According to the diagnostic equipment vendor recommendations, the zero thrust is best determined at the start of the closing stroke when the stem load transitions from tension to compression.
The licensee had marked zero thrust at the start of the opening stroke at the second thrust plateau.
This was the recommended analysis practice when the stem rejection load exceeded the packing load.
The licensee had calculated that the stem ejection load should exceed the packing load.
Under this condition, the thrust during the entire closing stroke would have been compressive and true zero would not be evident.
However, the inspectors noted that a pronounced zero plateau did appear on the closing stroke indicating that the stem ejection load did not exceed the packing load.
When the inspectors remarked zero at the apparent true zero plateau on the closing trace, the resultant thrust at torque switch trip (C14) was approximately 8429 lbf.
The calculated minimum required thrust setpoint (MRTS) for this MOV was 8637 lbf.
Considering other uncertainties in the
test, the inspectors did not consider that the 208 lbf difference was an immediate operability concern.
However, the inspectors were concerned that the torque switch setpoint would be outside the setpoint acceptance criteria.
I While acknowledging the abnormal appearance of the closing stroke thrust trace, the licensee maintained that their original marking of zero was correct.
Since the dynamic test had achieved only 22K of the 1150 psid design basis differential pressure, the licensee did not consider the test to be adequate to determine design basis performance.
According to the licensee's program, conclusions regarding valve factor and rate of loading were not valid unless at least 30 percent of the design differential pressure was achieved.
The 'licensee acknowledged the inspectors'oncern and committed to review their. evaluation of the dynamic and static test data for 2-FCV-37 to evaluate the zero thrust point and to resolve any operability questions that may result.
This issue is an open item (93-19-03:OPEN).
<
2.3.e.
Inadequate Documentation of Abnormalities The inspectors identified several abnormal features in the diagnostic traces that were reviewed.
However, the inspectors found that only a small per centage of these anomalies were specifically documented and evaluated in the test packages'.
The inspector were concerned because the qualitative aspects of the diagnostic signatures affected both the validity of the initial acceptance of the NOV test and the future capability to trend HOV mechanical problems.
For example, the diagnostic thrust signature for MOV 2-LCV-109 displayed an unusual trace feature that was not identified or evaluated by the licensee.
The. inspectors observed that the thrust trace displayed a substantial downward spike during the opening stroke.
The inspectors were concerned that the signature appeared to display a sensor reversal characteristic indicating an unacceptable sensor mounting and cal'ibration.
In response to the inspectors'oncern, licensee analysts again reviewed this trace.
Based on engineering judgement, the licensee concluded that the sensor was functioning properly.
They stated that the sudden change in thrust may have been caused when the balancing chamber.in the upper portion of the balanced-plug valve became pressurized with the onset of flow and the resultant balancing that followed.
As such, the licensee considered the signature to represent the valid operating characteristics of the NOV.
The inspectors found the licensee explanation to be reasonable.
Irrespective of the validity of this engineering hypothesis, the inspectors emphasized the need to document the evaluation of the qualitative characteristic for future reference in review the same abnormality.
During review of diagnostic traces for 2-9001B, the inspectors noted unusual thrust loading during the seating portion of the valve stroke.
The inspectors noted that there was no documentation of any such anomalies in the test evaluation.
After further review, the inspectors concluded that the SB (Limitorque actuator model) compensating spring pack appeared to be fully compressed during the seating of the valve.
The SB model utilizes a
compensating spring pack to cushion valve seating.
The compensating spring pack is normally only slightly compressed during valve seating.
Further, the inspectors noted that hard seat contact (Cll) was incorrectly marked at the point of full compression-of the compensating spring.'ll should have been marked earlier in the trace where the disk actually contacted the valve seat.
Licensee engineering personnel stated that it was expected that the SB compensating spring would be taken to full compression in this case.
The licensee contacted Limitorque who confirmed that it was acceptable to maintain the SB spring pack in a fully compressed state.
However, the inspectors were concerned that the anomalous trace was not documented in Section 10.0 of the test evaluation sheet.
Further, based on where Cll was marked, it appeared that the diagnostic signature analysts were unaware of the force trace characteristics associated with SB operators.
The l-icensee acknowledged the inspectors'oncerns and committed to provide more extensive documentation for future evaluations, including the following:
~ Basis for event marking that is'ifferent than standard practice
~ Basis for event marking that is less conservative than other potential alternatives
~ Evaluation of trace anomalies such as flow noise, unusual thrust spikes or characteristics, or other unusual behaviot.
The inspectors found the licensee proposed actions to be adequate.
2.3.f. Lack of Torque Measurement The licensee did not measure actuator output torque as part of their diagnostic instrumentation during testing..
The licensee relied on the torque switch limiter plate to prevent exceeding the actuator torque rating, actuator output at degraded voltage, and the spring pack capacity.
The licensee identified the size of limiter plates for all valves in the GL 89-10 program through use of design change packages.
All limiter plates were installed by refueling outage 2R5.
The inspectors observed one case out of the ten MOVs reviewed in which the limiter plate was not properly sized.
The inspectors reviewed the thrust calculation summary sheets for '2-8802B.
The inspectors observed that the specified limiter plate setting exceeded the motor capability at degraded voltage conditions.
Licensee personnel indicated that an incorrect unit gear ratio was used at the time the limiter plate setting was determined.
The licensee subsequently determined that the actual as-left torque switch setting was adequate since it was less than the calculated limiting setting.
The inspectors were concerned that the lack of torque measurement in the licensee's program limited the licensee's ability to determine proper actuator operation and to periodically verify actuator capability.
For example, the inspectors reviewed NCR DC2-93-EN-N014 which involved a failure of MOV 2-FCY-
(AFW Pump 21 steam supply valve) to close during a routine surveillance
test on March 15, 1993.
The root cause of the failure was determined to be corrosion on the upper bearing, combined with degraded stem lubrication.
These degraded conditions could not be detected by the licensee's diagnostic system prior to becoming self, evident when the valve failed to operate.
The inspectors noted that the licensee did not measure torque during diagnostic testing and was not back calculating the stem factor or'tem friction coefficient for each diagnostic test.
According to the licensee, actuator spring packs were tested prior to installation, and the spring constant and pr eload were determined.
Occasionally, actuator output torque was calculated using the measured spring characteristics and compared with expected values from the test data.
However, this was not performed routinely for all testing.
The licensee identified that in certain cases where the VOTES sensor could not be attached to the valve yoke, a Teledyne guick Stem Sensor (ASS) was attached to the valve stem to measure both thrust and torque.
In these cases torque would be measured and evaluated as supplemental information.
The licensee justified their lack of torque measurement based on the following features of their program:
1.
Overtorque protection for bypass seated valves was assured by analyzing actuator capability based on a valve factor of 0.6 and a stem friction coefficient of 0.2.
2.
Overtorque protection for torque and limit seated valves was achieved through the use of a controlled limited plate on the torque switch setting.
The inspectors noted that the licensee's assumption of a stem friction coefficient of 0.2 was generally conservative.
In response to the inspector's concern, the licensee committed to consider the following enhancements of their existing program:
~
Formalizing their check of actual torque. switch dial settings with measured thrust
~
Mot e extensive use of Teledyne ASS sensors for torque measurement.
Generic Letter 89-10 identified that the Idaho Nationa'l Engineering Laboratory (INEL) had concluded that diagnostic systems that measure both stem thrust and torque are best suited for predicting valve motor performance under design basis conditions.
In Supplement I, the response to guestion I stated that the uncertainty regarding the various phenomena that can affect MOY operability may necessitate, in some instances, the measurement of both torque and thrust.
The inspectors found the lack of routine torque measurement during testing to be a weakness in the licensee's progra.4 Periodic Verification of ROY Ca abilit
'hrough discussions with licensee personnel, the inspector found that the
, licensee planned to perform periodic verification of NOV capability on a five-year interval or every third refueling outage, whichever was longer, as recommended by GL 89-10.
However, the licensee had not yet established a
program for the periodic verification.
The licensee planned to use static testing only for periodic verification and to select valves for testing based on safety significance.
The licensee stated that they would justify the adequacy of their periodic verification program.
The inspector reviewed AR fA0258665 which identified that the licensee was monitoring the progress of ASIDE guidance in the area of post maintenance test requirements.
A previous open item in this area will remain open pending implementation of the licensee's periodic verification program (91-39-02:OPEN).
2.5 NOV Failures Corrective Actions and Trendin 2.5.a.
Inadequate Root Cause Determination The inspectors reviewed AR (Action Request)
PA0311830 which described licensee actions to resolve a recent failure of HOV 2-LCV-109.
The valve had failed to open twice during routine surveillance testing on July 15, 1993 despite having demonstrated worst case design basis capability during GL89-10 testing in November, 1992.
The licensee inspected the breaker cubicle and found no apparent problems.
Subsequently, with an operator stationed at the valve location, the valve opened electrically with no sign of abnormal operation.
Attempts to recreate the original failure were unsuccessful.
Licensee troubleshooting initially focused on an intermittent torque switch malfunction as the probable cause of the failure.
VOTES diagnostic equipment was set up and six opening tests were performed.
After the second of the six tests, the torque switch was replaced.
None of the diagnostic tests indicated any signs of abnormal operation.
Inspection of the original torque switch indicated no problems that would have resulted in failure of the valve to open.
However, after replacing the torque switch, the valve was returned to service on July 16.
The AR identified that no root cause evaluation was required.
The inspectors noted that the AR identified that the valve had stroked approximately 10 percent open before failure.. Since the torque switch was normally bypassed for at least 30'A of the opening stroke, the inspectors were concerned that the bypass switch setting appeared to be inadequate.
In response to the inspectors'oncern, the licensee determined that the bypass switch had been adequately set at 38/.
However with the torque switch actually bypassed at the point of failure, the inspectors questioned how the torque switch could be the cause of the observed valve failures.
The licensee stated that they had initially considered the reported position of the valve at the time of failure to be inaccurate.
The licensee issued a nonconformance report (NCR) to further "investigate the failure and address the accuracy of
the reported valve position.
The inspectors were concerned that the initial licensee corrective actions had not been thorough in, attempting to discover the root cause of an HOV failure.
Subsequent to the inspection, the licensee identified an auxiliary contact in the motor control circuit with high contact resistance and concluded that the defective contact was the-root cause'f the failure.
The licensee replaced the contact and returned the valve to service.
The adequacy of the licensee's corrective actions for 2-LCV-109 is an unresolved item pending review of NCRf DC2-93-EM-N037 (UNR 93-19-1:OPEN).
2.5.b Lack of Control of Valve Yoke Stiffness i
The inspectors reviewed AR4 311585 which documented the licensee's discovery of loose yoke-to-bonnet bolts after dynamic testing of MOV 2-8809A.
The inspectors noted that there was no evaluation of the effect of the loose bolting on the accuracy of the diagnostic data.
Changes in fastener tightness can substantially alter the effective yoke stiffness.
The VOTES sensor was calibrated for a specific yoke stiffness during static testing.
The calibration of the sensor had not been checked after the dynamic testing.
The licensee subsequently identified that, due to unexplained anomalies in the diagnostic signature, the test data for MOV 2-8809A had been considered invalid, and the valve had been scheduled to be retested during the next refueling outage.
The inspector discussed the need to control-all maintenance activities which
.could alter the yoke stiffness subsequent to calibration of the VOTES sensor.
In response to the inspectors'oncern for the control of yoke stiffness, the licensee contacted the VOTES force sensor manufacturer (Liberty) who stated that the force sensor should be recalibrated any time the yoke-to-actuator bolts were adjusted.
The licensee committed to revise their maintenance procedures to incorporate additional control of maintenance affecting yoke stiffness.
In addition, the licensee committed to require that any bolt adjustment work would invalidate the force sensor calibration for future
'esting until re-calibrated.
The licensee reviewed maintenance records for all other GL89-10 testing and determined that there were no other instances of uncontrolled bolt tightening which could have affected the accuracy of the test data.
The inspector found the licensee proposed actions to be adequate.
2.5.c Trending Through discussions with licensee personnel, the inspectors found that the licensee was still developing their program for trending of MOV failures.
No procedures were currently in place to implement a program.
The licensee had committed to have their program in place by December, 1994.
The licensee identified that a draft trending procedure (MA1.ID4).had been prepared.
A previous open item in this area will remain open (91-39-03:
OPEN).
2.6 Schedule
The inspectors reviewed the licensee's schedule for completion of their GL89-10 testing by December, 1994.
The licensee identified that they have eliminated the feedwater isolation valves (FCV-438,439,400,441)
from the scope of their dynamic test program because they were impracticable to test.
The licensee planned to use the Electric Power Research Institute (EPRI) test program to qualify HOVs which cannot be dynamically tested at design basis conditions.
The licensee was selectively utilizing an internal measurement system (Olympus Video-Image Scope) to obtain valve internal dimensions to assist justifying the applicability of the EPRI results.
The inspectors found the licensee's progress to be consistent with their committed schedule.
L7 gA The inspectors reviewed Audit 930051, 2R5 Naintenance guality Assessment, dated 5/21/93 which was performed by the licensee's guality Performance and Assessment Group.
The audit addressed GL89-10 testing and maintenance activities conducted during the refueling outage.
The inspectors reviewed the licensee's design control measures for speci.fying NOV setpoints.
The inspectors found that the setpoints were formally controlled under the licensee's design change notice (DCN) process.
The inspectors observed that the licensee procedures required that two analysts independently review the diagnostic signatures.
However, the identity of the analysts was not required to be documented.
The inspectors found this to be a potential weakness in the quality of the implementation of the licensee's program.
The inspectors noted that there had been no overview assessment of the licensee's program to determine if the program was being developed and implemented in an effective manner to achieve licensee commitments to GL89-10.
Through discussions with licensee personnel, the inspectors found that the licensee had planned an independent, self assessment of their GL89-10 program for July, 1993.
The inspectors concluded that the licensee was implementing their GL89-10 program through the testing and design control measures established by their quality assur ance program.
3.0 FOLLOMUP OF PREVIOUS OPEN ITEMS (92701)
50-275 90-16-1 CLOSED:
HOV S rin Pack Deficiencies This item involved a potential generic deficiency regarding spring pack relaxation in Limitorque actuators.
The inspector had been concerned that the licensee's'initial corrective actions appeared to narrowly focus on only
19'ertain model actuators following their discovery of three relaxed spring packs.
During this inspection, the inspector found that the licensee had expanded the scope of their original root cause investigation of the problem.
Voluntary LER 1-90-009 was subsequently submitted September 23, 1991.
The inspector reviewed the completed corrective actions for NCR DC2-90-EN-N014 and found them adequate.
This item is closed.
50-275-323 91-39-1 CLOSED:
NOV Switch Siz'n During the previous inspection of the licensee's NOV program, weaknesses,,had been identified in the licensee's sizing and setpoint calculation method:
rate-of-loading, valve stem friction coefficient, torque switch repeatability, seismic/dynamic loads and degraded voltage.
The inspector reviewed each of these areas in the current ICE-12 calculations and found that the licensee had revised the calculation method to incorporate conservative allowances for each area of uncertainty.
a. Rate-of-Loading (ROL):
The 'licensee had added a
)5% margin for ROL.
b. Valve Stem Friction Coefficient:
The licensee established actuator capability and setpoints based on the use of a conservative value 0.2 for valve stem friction coefficient.
c.
Torque Switch Repeatability:
The licensee incorporated a margin for torque switch repeatability in the determination of the minimum required thrust setpoint (NRTS).
The inspectors found that the licensee margin was consistent with Limitorque recommendations contained in Maintenance Update 92-02.
d.
Seismic/dynamic Loads:
The licensee added calculated seismic loads for the valve internals in their determination of the NRTS.
e.
Degraded Voltage:
In calculation 195F-DC, the licensee used the secondary level undervoltage relay setpoint (3785 volts)
as the minimum voltage on the safety buses and motor locked rotor current when calculating the minimum voltage available at the NOV.
The inspector found the program changes to be adequate.
This item is closed.
50-275-323 91-39-2 OPEN
Periodic Verification of NOV Ca abilit As discussed in Paragraph 2.4, this item will remain open pending implementation of the'icensee's program for periodic verification of NOY capability.
50-275-323 91-39-3 OPEN:
NOV Tr endin Pro ram
As discussed in Paragraph 2.5.c, the licensee was still developing a trending program.
The licensee had committed to establish a program by December 1994.
The inspector reviewed AR SA0258665 which the licensee had issued to track this commitment.
The AR indicated that a draft procedure (IDAP NAI.ID4) for the trending program had been prepared but not yet issued.
This item will remain open pending issuance of the licensee trending procedure.
50-275-323 93-03-03 OPEN
- Generic Concern for Valve Bonnet Leakoff Flow As discussed in Paragraph 2.1.a, this item will remain open pending completion of the licensee's evaluation of the generic concern for unrecognized bonnet leakoff flow.
No violations or deviations were identified.
4.0 UNRESOLVED ITEMS Unresolved items are matters about which more information is required in order to ascertain whether they are acceptable items, items of noncompliance or deviations.
An unresolved item is discussed in Paragraph 2.5.a of this report.
5.0
'EXIT MEETING An exit meeting was conducted on July 23, 1993.
During this meeting, the inspectors reviewed the scope and findings of the inspection.,
The licensee acknowledged the inspectors'indings.
The licensee did not identify as proprietary any information provided to or reviewed by the inspecto ATTACHNENT 1 DIABLO CANYON GATE AND GLOBE VALVE DATA VALVEStZK MANUPACTURER TESI'YNAMIC-CONDIIIONS VALVE PACTOR~
SIXM HUCTION COEFFICIENT LOAD SENSITIVE BEHAVIOR I-FCV-95 AFW Turbine Steam Inlet 2-FCV-37 AFWTurbine Stcam Supply 2-8105 Charging Pump Mini Flow 2-9003 B RHR Pump to Spray Hcadcr Crossconncct 2-8801 A Charging Injection to Cold Lcg 1-8821A SI Pump Injection to Cold Leg 2-LCV-109 AFW Pump Discharge Header Lcvcl Control 2-9001 B Spray Pump Discharge Isolation 2-8923 A-X SI Pump Suction 1-8803 B Charging Injection 4"-900It Anchor Darling Parallel Disk Gate 4 4004 Vclan Flex-Wcdgc Gate 2"-1500/t Vclan Globe 8"-3001 Anchor Darling Parallel Disk Gate 4"-15001 Vclan Flex-Wcdgc Gate 4"-9004 Vclan Flex-Wcdgc Gate 2"-900It CCI Balanced Plug Globe (Drag)
8"-150iF Anchor Darling Flex-Wedge 6"-1504'loyco/Walworth Split-Wedge Gate 4"-15001 Anchor Darling Parallel Disk Gate, 59% MBDP(O/C)
90% MBF 22% MEDP(O)
76% MEDP(C)
90% MBF(O/C)
2506 psid (0/C)
96% MEDP(O)
98% MEDP(C)
50% MEF(O/C)
231 psid (0/C)
112% MEDP(O/C)
91% MEF(O/C)
2545 psid (0/C)
500% MEDP(O)
93% MEDP(C)
89% MEF(O)
51% MEF(C)
172% MEDP(O)
98% MEDP(C)
98% MBF(O/C)
38% MEDP(O/C)
)40% MEF(O/C)
218 psid (0/C)
88% MEDP(O/C)
67% MEF(O/C)
70% MEDP(O/C)
12% MEF 86% MEDP(O)
82% MEDP(C)
76% MEF(O)
55% MEF(C)
0.43 Unavailablc 1.1 (C)
0.3 (C)
0.1 (0)
0.47 (C)
0.25 (0)
0.54 N/A 0.14 (C)
0.28 (0)
0.4 0.3 Unknown Unknown Unknown Unknown Unknown Unknown Unknown Unknown
,Unknown Unknown N/A LimitSeated Unavailable 31.7%
7.9%
29.8%
12.2%
Unavailablc-24.9%
Unavailable N/A LimitScatcd Thc dynamic valve factors listed were calculated by the liccnscc using a mean scat diameter.
A negative number indicates that the thrust obscrvcd at CST during the dynamic test was greater than thc thrust obscrvcd at CST during thc static test.
MEDP - Maximum Expected Differential Pressure (Design Basis Condition)
MEF - Maximum Expcctcd Flow (Design Basis Condition)