ML20005A655
| ML20005A655 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/26/1981 |
| From: | Colbert W DETROIT EDISON CO. |
| To: | Kintner L Office of Nuclear Reactor Regulation |
| References | |
| EF2-53888, NUDOCS 8106300548 | |
| Download: ML20005A655 (6) | |
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Detroit 2000 second Averce Devo t. M.ch::;an 48226
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- (313) 237 8000 June 26, 1981 EF2-53888 Mr. L. L. Kintner Division of Project Management Office of Nuclear Aeactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Dear Mr. Kintner:
Reference:
Enrico Fermi Atomic Power Plant Unit 2 NRC Docket No. 50-341
Subject:
Amended Response - PSB-1 Adequacy of Station Electrical Distribution System Voltage The following is a suanary response of Fermi 2 regarding Branch Technical Position PSB-1 " Adequacy of Station Electrical Distri-bution System Voltage." This response was requested during the Electrical Audit (June 23, 1981), by Mr. A. Saeed.
PSB-1 Section B.I.a The voltage and time setpoints selected as a result of our calculations are as follows.
120kV (Giv. 1) 345kV (Div. 2)
"oltage Tine Delay Voltage Time Delay
(%)
(Sec.)
(%)
(Sec.)
4.16kV Buses Primary UV 73.2 2
73.2 2
Secondary UV 92.7 17 87.9 18.5 480 Volt Buses Primary UV 65.0 2
65.0 2
Tolerance, all voltage settings +1%
Tolerance, all time delay settings +3%
1 Also reference EF2-53522 (attached) and also the response to Section B.3 below.
khk B.I.b Reference EF2-53522.
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Mr. L. L. Kintner June 26, 1981 EF2-53888 Section B.I.c Reference the EF2 response to Question 222.31B. The response states that we are in compliance with appli-cable sections of IEEE Standard 279-1971.
B.2 Reference the EF2 response to Question 222.33 and EF2-53522.
B.3 Attachment I to this letter summarizes the methods used to comply with the section.
i B.4 Reference EF2 response to Question 222.32B.
Sincerely yours, William F. Colbert Technical Director Enrico Fermi Unit 2 MDF/dlo Attachments (2) i J
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ATTACHNENT 1
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System Voltage Calculations The following'i:s'an excerpt from Design Calculation 835 and a tabulation of system voltages for the various limiting cases.
U Assumptions, Criteria, and Boundaries l
- High voltage and low impedance condition was assumed ;o. occur during
~ refueling period'with emergency diesel generators text loaded. One EDG, however, was assumed to be tested at a time. For Division I, since peakers can be connected to the 120kV system, and their~ ratings are higher than EDGs, two (2) peakers are, therefore, simulated in-stead, at a time.
. Low vettage and high impedance condition was. assumed to occur during
- full plant generation and a losa of coolant accident' (LOCA) occurs. -
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Many of the large plant auxiliaries suchas-heater feed pumps and con-denser pumps are running near capacity. The BOP loads are not auto-4 t
matically but manually tripped. The operator, however, is unlikely to trip these loads for several minutes into the acc~ dent. The scram loads, in addition, are automatically initiated. This hot standby j
j data was extracted from design calculations.
Acceptance criteria were based on the steady-state and transient
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voltage condition.
t In the steady-state voltage condition, voltages must not exceed j;
the ranges established by manufacturers or' industry standards for
-continuous operation.- When the; system is at high voltage and low j
impedance condition, short circuit currents,. if should occur, must not exceed the momentary and interrupting capability of the breakers.
In the period after' the LOCA, the most severe transient occurs when the Residual Heat Removal (RHR) and Core Spray pumps start.
Two (2) RHR pump motors will start simultaneously followed five 1
(5) seconds.later by two'(2) Core Spray pump motors. The minimum voltage for the transient period at.the RHR motor terminals must not drop below'75% its rated voltage to assure adequate torque margin. MCC contactor coils may not pick up until voltage is
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recovered but, if already energized, must not drop out.
Solenoid operation is designed.to fail' safe.
E Boundaries: Voltage ranges established by manufacturers and standards
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are:
b Steady State I
Motorsi ' + 10% voltage rating i.e. 1.0577 pu &.8654 pu @ 4160V and l'.0542 pu &.8625 pu @ 480V.
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+10%, -25% voltage rc;ing, i., 132V & 90V @.120V base.
' Control:
+10%, -20% voltage rating,'i.e. 132V & 96V @ 140V base.
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Attachment i Page 2
. Transient Minimum voltage for'the transient period at'the RHR motor terminal is-75% @40007 or.72115 pu @ 4.16kV base.
= -55%) criteria for transient
.Less'than 55% (pick up = 70%,. dropout condition is to prevent dropout.
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4 Voltage Calculation Sun,sary Degraded Grid Relaying Voltages, p.u. (Base = 4160 or 480 volts)
I Degraded grid, max. load High voltage, light load z Staady State 3
.120kV swyd.
.94 1.07 Bus 64B
.999 1.025 Bus 64C
.999 1.025
' Bus 72B
.997 1.036 Bus 72C
.983 1.025 Bus 72EA 1.003 1.04 8 Bus 72Eb 1.002 1.04 8 Bus llEA
.999 1.025 Bus 12EB
.999 1.025 3
345kV Swyd.
.95 1.06 Bus 65F
.874 1.046 Bus 65E
.874 1.04 6 Bus 72E
.929
.997 Bus 72F
.929
.995 Bus 13EC
.874 1.C48
- Bus 14ED
.874 1.045 Bus 72EC
.935
.998 Bus 72ED
.933
.995 IHot standby, maximum load, emergency diesel generation and peakers off.
' Plant down; system voltage high; peakers on.
3For the study case, the voltage was raised above the maximum expected, to provide margin in the study.
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4 Degraded grid, transient 120kV Switchyard
. 907 Bus 64B
.738 Bus 64C
.739 Eus 72B
.720 Bus 72C
.700 Bus 72EA
.728 Bus 72EB
.727
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Bus llEA
.738 Bus 12EB
.738 345kV Switchyard
.946 Bus 65E
.756 Bus 65F
.755 Bus 72E
.784 Bus 72F
.783 Bus 13EC
.755 Bus 14ED
.755 Bus 72EC
.801 Bus 72ED
.797 RER Motor A
.76 RHR Motor C
.76 5
RHR Motor B
.75 RHR Motor D
.75 O
i Start.two RHR pumps, hot standby, maximum load, emergency diesel generatars off.
5 Voltage at terminals of RHR motors.
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m Detroit 20M Saconc Avenue emC l O Detroit, Michigan 48226 I
(313) 237-8%C June 11, 1981 EF2-53522 i
Mr. L.L. Kintner U.S. Nuclear Regulatory Commission Division of Proje.. Management Office of Nuclear Reactor Regulation 7920 Norfolk Avenue Bethesda, Maryland 20014
Reference:
Enrico Fermi Atomic Power Plant, Unit 2 NRC Docket No. 50-341
Subject:
Branch Technical Position PS3-1 Degraded Grid Protection
Dear Mr. Kintner:
Provided below is the Edison position regarding degraded grid relaying.
These items confirm a telephone conversa-tion of June 10, 1981 between Messrs. A.
Syed and R. Fitz-patrick, NRC, and Messrs. M. Feathan and J. Honkala, Detroit Edison.
The item numbers balow reference appro-priate section nunbers of the subject Branch Technical Position.
Section B.l.(a)
NRC guidance:
Provide calculations for degraded gric relay serpoints, time delays, and tolerances.
The logie used in the calculations should include the criteria of precluding damage to Class IE equipment.
Fermi 2 resconse:
Calculations will be furnished, under separate cover, showing the methodology and criteria used in selecting the setpoints, time delays, and tolerances.
Please note that the calculations have not as yet been verified by an independent checker as recuired by QA procedures.
3.1.(b)
NRC guidance:
Fermi 2 has the option to eliminate item 1 the alarm recuirement if the calculations show that the degraded grid relaying should take action with the minimum time delay.
s Mr. L.L. Kintner EF2-53522 page two-B.l.(b)
Iten 1 (con't)
Fermi 2 response:
The above referenced calculations indicate that the time delay to actuation should be minimized, once the degraded grid voltage condition has occurred.
Fermi 2 has provided an alarm to give advance notice to the operator that a low grid vol-tage condition exists.
Thus, the alarm relay set-point is~ set above the degraded grid setpoint, eliminating any time delay associated with the alarm.
B. l. (c)- NRC guidance:
The degraded grid relay, and its Item 1 associated components, including the potential r.ransformer feeding the relay, must all be quali-fied to Class IE requirements.
Fermi 2 response:
The relays will be qualified to Class IE requirements._
The relays will be located in, and connected to, the Class IE switchgear and fed from the bus potential transformers, which are also qualified to Class IE requirements.
B.l.(c)
NRC guidance:
A minimum of two degraded grid re-Item 3 lays are required per division, and both must operate to indicate separrtion from the offsite power system.
Fermi 2 resoonse:
Fermi 2 complies with this requirement.
Details of the design will be pro-vided in drawings as part of the NRC electrical audit, scheduled for June 23, 1981.
3.1.(c)
Fermi 2 resconse:
Fermi 2 does not have any auto-Item 6 matic oypasses of the degraded relaying.
3.2 NRC cuidance:
The Fermi 2 position regarding this section is contained in the Fermi 2 response to l
Question 222.33 (FSAR Appendix E.5).
The NRC indicated that this position meets the require-
)
ments of Section 2 and is acceptable.
3.3
.iRC guidance:
The Fermi 2 cc=mitmenc as described in FSAR Section 8.2.25 (revised April 1979) satis-fies the requirements of this section and is accept-i able.
B.4 NRC zuidance:
The Fer=i 2 resconse to Question I22.32A mee*.s the requirements of this section and
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is acceptable.
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Mr. L.L. Kintner EF2-53522 page three l
As stated earlier, design calcu32tions will be provided under separate cover.
Drawings (logic diagrams and sche-
. matic diagrams) will be available for NRC review at the Electrical Audit.
Please advise me i= mediately if any further information is required.
Sincerely yours, f$w
.)
William F. Colbert Technical Director Enrico Fermi 2 Project WFC/mle e
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