ML20035B278
| ML20035B278 | |
| Person / Time | |
|---|---|
| Issue date: | 03/09/1993 |
| From: | Gill P Office of Nuclear Reactor Regulation |
| To: | Ranft D WORKING GROUP 4.4, SC-4 |
| References | |
| NUDOCS 9304010131 | |
| Download: ML20035B278 (7) | |
Text
____
March 9,1993 Mr. Donald J. Ranft, Chairman Working Group 4.4, SC-4 P. O. Box 388 forked River, New Jersey 08731
Dear Mr. Ranft:
Enclosed are my review comments on the finalized draft Guide for MOV Motor Application, Protection, Control and Testing in Nuclear Power Generating Stations (P1290). As you know, I am replacing Mr. W. Farmer, who has retired from the NRC, on SC-4.
I look forward to meeting with you and other SC-4 members during the March 30-31 meeting in Denver.
If you have any questions, you may reach me at 301-504-3316.
l5/
Paul S. Gili Electrical Engineering Branch Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
Review Comments on Draft P1290 DISTRIBUTION w/ enclosure JRichardson, NRR CHBerlinger, NRR PGill, NRR PDR Central Files DE R/F EELB R/F Document Name:
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Enclosure Review Comments on Draft P1290 Comment 1:
Page 4,
References:
Need to add GL-89-10, " Safety Related Motor-0perated Valve Testing and Surveillance," and Supplement I to GL-89-10 as a reference. Also, revise the document as necessary.
See comment 11 for details.
Comment 2:
Page 9, See the attached marked-up page 9 of draft P1290 for comrents.
Comment 3:
Page 10, First paragraph, " Source Voltage" Similar to the discussions under AC motors, the starting of large loads with resultant voltage drop should be included in the source voltage discussion for DC motors.
Comment 4:
Page 10, First paragraph, where the MOV operates in the....
Motor operated valve is abbreviated as MOV on the FORWARD page.
Metal oxide varistor is abbreviated as MOV on page 33.
Resolve this difference.
Comment 5:
Page 13, The effects of reduced voltage and elevated temperature on motor torque output may be calculated independently and then multiplied.
Provide typical examples of multiplication factor used for the elevated temperature on motor torque output to help the reader understand this issue.
Comment 6:
Page 15, Protection:
Provide additional information regarding Regulatory Guide (RG) 1.106, on bypassing thermal overload (TOL) relays during safety function and precautions required for the trip setpoint of TOL, if not bypassed.
Frequently, TOL setti 3 is overlooked after MOV modifications. Also, need a discussion on protection for jogging type operation.
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. Comment 7:
=
Page 17
" Thermal Overload Relays" The trip setpoint of TOL should consider the following:
a) variations in the ambient temperature at the installed location of the overload protection devices and the valve
- motors, b) inaccuracies in motor heating data and the overload protection device trip characteristics and the matching of these two items, c) setpoint drift, Comment 8:
Page 19, Section 5.? " fuses" Fuse selection, also, should consider the following:
a) variations in the ambient temperature at the installed location of the overload protection devices and the valve
- motors, b) inaccuracies in motor heating data and the overload protection device trip characteristics and the matching of these two items, c) jogging operation.
Comment 9:
Page 38, First paragraph, This degradation could go undetected during normal maintenance and render the actuator incapable of performing its intended function. The additional bypass feature could degrade the overall reliability of the circuit.
l The TOL should not be bypassed during normal maintenance.
If l
TOL is bypassed during loss of coolant accident (LOCA) only, l
then reliability will not be compromised.
Comment 10:
Page 58, Section 6.3.2 (b), Repeated cycling places an added burden on the VAM and its protection, and must be evaluated.
Aad a discussion on how to select TOL and fuse for throttling control.
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. Comment 11:
Page 67, Section 7.0 Need to review against GL-89-10, " Safety Related Valve Testing and Surveillance" and Supplement I to GL 89-10 and revise this section accordingly P.s necessary.
GL 89-10 and its supplement provide guidance in testing, inspection, and maintenance of MOVs so as to provide the necessary assurance that they will function when subjected to the design basis conditions (i.e. degraded voltage) that are to be considered during both normal operation and abnormal events within the design boris of the plant. Additionally, these documents provide guidance for selecting and setting all switches (i.e.. torque, torque bypass, position limit, overload) and in situ M0f testing at design basis degraded voltage conditions.
Comment 12:
Page 84,
" Calculation Method," Second sentence of first paragraph The motor impedance is found by dividing the rated voltage by the locked rotor current at locked rotor power factor.
Should be changed to "The motor impedance durina startina is found by dividing the rated voltage by the rated locked rotor current at rated locked rotor power factor."
Comment 13:
P;ge 85 Last paragraph Consolidate this paragraph with the first paragraph on page 84.
Comment 14:
Page 86, Motor Resistance - Rated Voltaae x PF (line to neutral)
LRA x,/3 Should be changed as Motor Resistance - Rated Voltaae x rated locked rotor PF during starting Rated LRA x V3 (line to neutral)
Motor Reactance shall be changed similarly.
Comment 15:
Page 89, Note: Minimum source voltage is derived by the battery discharge profile for the time that the MOV is called on to perform its design function.
Need to consider the voltage drop between the battery terminals and Distribution Board / or MCC.
o
. Conment 16:
Page 92, Locked Rotor PF = 0.9 Fig. 14 shows a PF curve.
It is not clear how the PF value 0.9 is obtained from this curve.
Provide a clarification on how this PF value is obtained from Figure 14.
Comment 17:
.i Page 92, Ambient temperature What will be the motor torque after the application of l
temperature factor?
l Example should include different ambient temperatures (Normal, LOCA, etc.) of motor, cable and overload heaters.
Comment 18:
Page 94, Motor Resistance and Reactance
)
Examples 1 and 2 uses i.he same motor data (Fig.14), but calculate two different values of motor impedance.
For the same.
motor, why the starting impedance will be different? Also, locked rotor power. factor can not be same at different locked rotor currents. Provide an explanation of motor characteristics at different points of motor starting.
i Comment 19-Page 96, Locked Rotor PF = 0.79 It is not clear how the locked rotor PF of 0.79 is obtained from i
Fig. 15? Provide a clarification on how this value is obtained i
from Figure 15.
1 Conment 20:
Page 101, Rg = 0.127 x 0.97 - 0.123 ohms Why this is required? Provide. a basis and/or an explanation.
Comment 21:
Page 102, Motor Resistance = R, = 250 13.51 ohms.
18.5 This is the same motor as in example 5, having R, = 8.621 ohms.
Why is the motor resistance different in these examples?
Comment 22:
Page 103, Torque Evaluation No margin is provided between minimum torque assessment (10 ft lbs) and the required torque (10 Ft lbs.).
Is this still acceptable?
[ Refer to Section 4.3.1, Page 13]
. Comment 23:
Page 105, First paragraph, Typically, a point should be plotted that is 150 percent of locked rotor amperes for 0.25 seconds.
Comment:
Because of system asymmetry, over voltage, etc. may require 200%
of LRA and for up to 2 seconds.
Provide rationale for using 150% and 0.25 seconds.
Comment 24:
Page 107, DATA Acceleration time of one (1) second appears too fast.
Provide a discussion and basis for using this time? Maximum ambient temperature - 104* should read 104*F.
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r Draft 4 breaker, contactor and containment penetration assemblies are typically negligible and normally need not be considered; care must be exercised to consider all resistances in the circuit.
4.2.1.3 Effect of Locked Rotor Power Factor l
Valve actuator motors have a unique design that can result in significantly different operating characteristics. Continuous duty motors are rated in horsepower which implies a constant torque. VAM's are neither continuous duty nor constant torque. However, they can be charAh as short duty time /high stamng torque motors. A high startmg torque design requires a high rotor resistance. This hgi h romt retiet2nce results in an elevated locked rotor (cu~d S&)
power factor. Unlike large% duction moton. which have typical locked rotor X
CM o.5 vespec4MIy]
X power factors of 0.yve actuator motors may nave startmg power factors of 0.95. Specific motor manufacturers data should be obtained. These high locked rotor power factors can have a significant effect on calculating motor terminal voltage at startmg conditions.
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