ML20041D310
| ML20041D310 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 02/18/1982 |
| From: | Stolz J Office of Nuclear Reactor Regulation |
| To: | Bauer E PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| IEB-79-01B, IEB-79-1B, NUDOCS 8203050192 | |
| Download: ML20041D310 (7) | |
Text
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FEBRUARY 1 8 WE Eluommnt :
L PDR RIngram Gocket File ORB #4 Rdg MFai rtile f4KL., VUK DEisenhut RPrevatte-2
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Dockets !!os. 50-277 and 50-270 AE0D S
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!!r. Edward G. Bauer, Jr.
TBarnhart-8 Vice President and General Counsel LSchneider 9
% ~, /4 E Philadelphia Electric Conpany DBrinkman A'ch U[
2301 liarket Street CMiles Philadelphia, Pennsylvania 19101 RDiggs Ibar !!r. Bauer:
Our letter of June 2,1977 initiated a review of the degraded grid voltage protection for the Class lE electrical power systems at the Peach Botton Station Units 2 and 3.
By letters dated July 21 and December 22, 1977, December 21, 1979,!! arch 21, 1930 February 13 June 16 and July 22, 1981 you proposed plant nodifications and Technical 3pecification (TS) changes to enhance the level of protection at Peach Botton.
We have completed our review of your design changes and plant modifications, and based on the enclosed Safety Evaluation, we conclude that the Peach Botton Station Class lE electrical power systens are adequately protected against the effects of degraded grid voltage.
You subnitted TS changes, to cover the modifications, dated !! arch 21, 1980 Ilowever, letters from Philadelphia Electric Company dated October 14, 1980 and February 13, 1981 provided changes to the setpoints, tolerances and surveillance requirements. Additional TSs implementing these changes need to be subnitted in order for us to complete our review. This sub-nittal should be as a supplenent to your March 21, 1980 submittal.
Kindly subnit these supplemental TSs within 45 days of receipt of this l etter.
- Sincemly, 80RIGIW.L SIcarr 37(
(J0lin F. SIO 4=
John F. Stol::, Chief Operating Reactors Branch #4 8203050192 820218 PDR ADDOK 05000277 Division of Licensing P
Enclosure:
Safety Evaluation cc w/cnclosure:
See next page wL
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UNITED STATES' 8
( ' (n NUCLEAR REGULATORY COMMISSION 9
WASHINGTON, D. C. 20555 February 18, 1982 Dockets Nos. 50-277 and 50-278 f
Mr. Edward G. Bauer, Jr.
Vice President and General Counsel Philadelphia Electric Company 2301 Market Street Philadelphia, Pennsylvania 19101
Dear Mr. Bauer:
Our letter of June 2,1977 initiated a review of the degrided grid voltage protection for the Class 1E electrical power systems at the Peach Bottom Station Units 2 and 3.
By letters dated July 21 and December 22, 1977, December 21, 1979, March 21, 1980, February 13, June 16 and July 22, 1981 you proposed plant modifications and Technical Specification (TS) changes to enhance the level of protection at Peach L0ctom.
We have completed our review of your design changes and plant modifications, and based on the enclosed Safety Evaluation, we conclude that the Peach Bottom Station Class lE electrical power systems are adequately protected against the effects of degraded grid voltage.
You submitted TS changes, to cover the modifications, dated March 21, 1980.
However, letters from Philadelphia Electric Company dated October 14, 1980 and February 13, 1981 provided changes to the setpoints, tolerances and surveillance requirements. Additional TSs implementing these changes need to be submitted in order for. us to complete our review.
This sub-mittal should be as a supplement to your Parch 21, 1980 submittal.
Kindly submit these supplemental TSs within 45 days of receipt of this letter.
Sincerely, j
f 3 !
J F. Stolz, Chief rating Reactors Branch #4 Division of Licensir.g
Enclosure:
Safety Evaluation cc w/ enclosure:
'See next page O
e 4
p
Philadelphia Electric Company ccw/ enclosure (s):
Eugene J. Bradley Philadelphia Electric Company Regional Radiation Representative Assistant General Counsel EPA Region III 2301 Market Street Curtis Building (Sixth Floor)
Philadelphia, Pennsylvania 19101 6th and Walnut Streets Philadelphia, Pennsylvania 19106 Troy B. Conner, Jr.
1747 Pennsylvania Avenue, N.W.
M. J. Cooney, Superintendent Washington, D. C.
20006 Generation Division - Nuclear Philadelphia Electric Company 2301 Market Street Philadelphia, Pennsylvania 19101 Government Publications Section l
Thomas A. Doming, Esq.
State Library of Pennsylvania l
Assistant Attorney General Education Building Department of Natural Resources Commonwealth and Walnut Streets Annapolis, Maryland 21401 Harrisburg, Pennsylvania 17126 Philadelphia Electric Company ATTN: Mr. W. T. Ullrich Peach Bottom Atomic Power Station Mr. R. A. Heiss, Coordinator Delta, Pennsylvania 17314 Pennsylvania State Clearinghouse Governor's Office of State Planning Albert R. Steel, Chairman and Development Board of Supervisors P. O. Box 1323 Peach Bottom Township Harrisburg, Pennsylvania 17120 R. D. il Delta, Pennsylvania 17314 Curt Cowgill U.S. Nuclear Regulatory Commission Office of Irspection and Enforcement Peach Bottom Atomic Power Station P. O. Box 399 Delta, Pennsylvania 17314 M'r. Ronald C. Haynes, Regional Administrator U. S. Nuc1 car Regulatory Commission, Region I Office of Inspection and Enforcement 631 Park Avenue King of Prussia, Pennsylvania 19406 e
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UNITED STATES i
NUCLEAR REGULATORY COMMISSION W ASHINGTON. D. C. 20555 i
g.....f SAFETY EVALUATION REPORT BY THE OFFICE OF NUCLEAR REACTOR F.EGULATION PEACH BOTTOM ATOMIC POWER STATION, UNITS 2 AND 3 DOCKETS h05. 50-277 AND 50-278 DEGRADED GRID VOLTAGE PROTECTION FOR THE CLASS lE SYSTEM Introduction and Summary By letter dated June 2,1977 we transmitted the criteria and staff positions pertaining to degraded grid voltage protection to the Philadelphia Electric Company. By letters dated July 21, 1977, December 22, 1977, December 21, 1979, March 21, 1980, February 13,1981, June 16,1981 and July 22, 1981, the licensee proposed certain design modifications, and changes to the Technical Specifica-tions (TSs). A detailed review and technical evaluation of these proposed modifications and changes to the TSs were performed by Lawrence Livermore Laboratory (LLL), under contract to the NRC.
This work was reported to the NRC by LLL in their Technical Evaluation Report (TER) UCID-19115, dated November 3, 1981 We have reviewed this TER and concur in its conclusion that the pmposed electrical design modifications are acceptable. However, TSs to cover the surveillance requirements, allowable limits for setpoint and time celay,,and limiting conditions for operation of the second-level undervoltage relays have not yet been submitted.
Evaluation Criteria The criteria used by LLL in its technical evaluation of the proposed changes include GDC-17 (" Electrical Power Systems") of Appendix A to 10 CFR 50; IEEE Standard 279-1971 (" Criteria for Protection Systems for Nuclear Power Generating Stations"); IEEE Standard 308-1974 (" Class lE Power Systems for Nuclear Generating Stations"); ANSI Standard C84.1-1977 (" Voltage Ratings for Electrical Power Systems and Equipment-60Hz"); and staff positions defined in our June 2, 197.7 letter.
l Discussion and Evaluation A.
Existing Undervoltage Protection The existing undervoltage protection at Peach Bcttom uses three sets of relays to detect a loss of voltage, shed the load and restore voltage l
on each of the eight 4160 volt Class lE buses.
The function of the relays for each Class 1E bus is as follows:
(See attached Figure 1) l 1.
An inverse time delay relay monitors the voltage on the source of each startup transformer supply breaker to each 4 kv Class lE bus.
l These relays are set to operate at a voltage between 2275 and 2450 volts with a time delay of approximately 1.75 seconds. Actuation of either relay will trip the-affected startup source breaker to.
its respective bus.
. 2.
An HGA relay monitors the voltage on each bus. The relay functions with no appreciable time delay when the voltage on the bus falls below 1225 volts. Actuation of this relay will initiate load shedding and provide a pennissive signal to allow the affected bus to transfer to the alternate source.
If this alternate source is not available the relay will provide an automatic start signal to the emergency diesel generator.
3.
An SV relay with a setpoint of approximately 3675 volts monitors the Class lE bus. Actuation of this relay will initiate load sequencing once the voltage has been restored to the Class lE bus.
Load shedding is maintained on Class 1E buses when they are energized by the emergency diesel generators. However, the load shedding circuitry is not initiated until the voltage falls below 1225 volts.
B.
Proposed Modifications The licensee has proposed the addition of the following equipment to provide protection for Class lE equipment under degraded voltage conditions:
(See Figure 1) 1.
Install a I,TE-270 relay with a 60 second timer, on the source side of each startup source, to each Class lE bus, and set to 3745 volts, 90% of normal. Actuation of this relay, after a 60 second time delay, will trip the startup source breaker.
Loss of voltage on the 4160 volt bus actuates the HGA relay which initiates a trans-fer to the alternate source.
The 60 second time delay is to allow the automatic tap changer on the startup transformers sufficient time to adjust and correct the degraded voltage condi-tion.
2.
A CV-6 relay (inverse time) is installed on the source side of each startup source to'each Class lE bus. This relay, will be set at 3619 volts (87% of normal) with a time delay of 60 seconds or less. Actuation of this relay will perform th,e same action as the ITE-27D and provides inverse time delay, with degrading voltage, for protection of the Class lE equipment.
3.
A TD (time delay) relay with a setpoint of 6 seconds is also installed on the source side of each startup source to each Class lE bus. A safety injection signal, in addition to starting the diesel generator, will actuate the TD relay which bypasses the 60 second timer of the ITE-27D relay and provides control room annunciation. This relay limits the exposure of Class lE equip-ment to degraded voltage conditions for a maximum of 6 seconds.
The licensee's proposed design does not provide coincident logic to l
preclude spurious trips to conform to BTP-PSB 1.
However, spurious action of one undervoltage relay wi'll only transfer the affected bus to the alternate power source and would require actuation of a second undervoltage relay to transfer the bus to the diesel generator.
If ye
3-an ITE-27D relay should fail to operate it is backed up by the CV-6 inverse time relay.
Therefore, we conclude the proposed modifications are acceptable.
The licensee has also proposed to bypass individual relays with a test block to perform the required periodic testing. An individual relay, undergoing testing, will be bypassed only for a test of short duration.
Installation of this test block will provide annunciation in the control room.
The licensee's analyses for a design basis event assumes that only three of the four buses of each train are operable. Based on the above, we conclude that the licensee's approach to meeting our requirements for coincident logic and testing is acceptable.
Conclusions Based on our review of the licensee's submittals and the LLL TER we conclude that:
1.
The proposed degraded grid modifications will protect the Class lE equipment and systens from sustained degraded voltage conditions on the offsite power source.
2.
The degraded grid undervoltage relays are not coincident which is a deviation from our position.
However, if spuriously actuated, the relays do not transfer the Class lE equipment to the onsite power source, but to the alternate offsite power source.
If the alternate source is degraded or not available, the transfer will then be to the onsite source.
This circuitry provides coincidence at a system level. This deviation has been determined to be acceptable.
3.
The licensee's decision to maintain load shedding while the emergency diesel generators are supplying the bus, based on a load shedding setpoint of 25% of nominal voltage, is acceptable.
'4.
The existing TS for testing the onsite power system is adequate.
The following NRC staff personnel have contributed to this Safety Evaluation:
Morton Fairtile and Richard Prevatte.
Dated:
February 18, 1982 O
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