ML19345D601

Forwards Response to 801024 Request for Addl Info Re Generic Issue of Onsite Power Sys

ML19345D601
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	12/12/1980
From:	Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Curtchfield D Office of Nuclear Reactor Regulation
References
NUDOCS 8012160182
Download: ML19345D601 (5)

Text

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iEC letter dated October Eh,1980, requested additionsl informatien as clarifi-cation fcr previcus Censumers Fever Cc pany respcnses, dated June ik,1975, end August 22, 19eC, en the subject topic. Specific respenses to the October 2k, 19S0, encicsure questiens are provided by Attachments I and II to this sutritta'.

~he respcnses provided herein chould te sufficient to rescive this topic except .c,. + w o..equee+,4 e, w. 4,,_.,.c, e c.4,4. c. 4cn. ney c .#a*,,e ".aak".*nal S e.4 a*.'n s v. -e. o 3 s. ~y fcr this subj ect will te sutritted by Februa y 1,1981, as a change request (see n,,,,ac.. T, T.,, e. A,,T. w David F Ecffman (Signed) .na. 4 u e a.c.co 4 4 v n :,4a a .. s +o ro+, C. .?...,,e a.,. r4,e s4. -, n m.v .2. 1 rector, egicn ,.,22., n. 7a..., - Cp nnu

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i FISFONSE TO REQUEST FCR ADDITIO:IAL INFORMATICN - 3E BIG ROCK POI:T FLA'!T EEGRADED CRID VOLTAGE Ite: 1 In Reference a, Item lb, the lowest h80V bus voltage is L137 (0.8608 P.U.) for Eus lA. What is the voltage on Bus 23 (safety bus) for this case? Res;cnse to Iter 1 Reference a, Item ib lists voltage values for Ius lA and Eus 2A. Sus 2A is physically located directly adjacent to Bus 23 with only a very short lem %h of cable between then. The analysis that was performed assuned negligible voltage drop between these two, so that the voltage values for Bus 2A are identical to these at 23. This is also true for the cther Eus 2A values given in the respons? to Ite= 1. Iten 2 In Reference a, there is a difference between the full lead voltages in Item 1 and 5 Please explain. Respcnse to It c: 2 Reference a, Iten 1 requests data showint the maximum and minimum voltages and Ite: 5 requests the vcltage analysis for full load conditions. Item 1 does not ask for full load voltages and therefore they were not given. It is not valid to assure that the full load voltages would be identical to the minimum voltages because the minimum voltages occur when the generator is down and full lead voltages occur when the generator is on. A similar argument can be rade for trying to conpare no load voltages with maximum voltages. Iten 3 In Reference t, reepense 1A, the lowest voltage at the safety tus (23) is stated as being 3dTV. In Reference a, the voltages are higher (h23 volts). What is the reason for this difference? Res;cnse to Item 3 The lowest voltage at Bus 23 in Reference b was obtained fren a study that was performed by Bechtel in response to a request from the URC dated August 13, 1976. The value was contained in a tabte and the basis for this number was not given in the study. This value was used to determine the need for the addition of a second level of undervoltage protection. This modification is being installed during the present refueling outage. In the span of four years, the plant's station power configuration has been nodifi-ed. The icwest value at Bus 23 in Reference a represents the results of our latest

Attachment I (Cont'd) 2 analysis using the present .icn power configuration. This analysis was veri-fled by test and the ter

ults were submitted to the HRC in a letter dated August 29, 1980. Ther e, information contained in Reference a is the most current and should be used for any further evaluations by the NRC.

Item b Please explain how the new undervoltage protection system can te classified as lE to meet IEEE Standard 279 when it is located on a ncn-class II bus. Restense to Item L The new undervoltage protection syste= is being installed on the 2h00V switchgear whi:h is en the Q-List. This question is ambiguous because IEEE Standard 279 cakes no mention of Class IE equipment, and does not preclude the use of non-Class IE equipment. The overall purpose of this =cdification is to protect the safety equipment frc= degraded grid voltage frc= the transmission circuits. At Big Rock Point, i' is necessary to go through the 2kCOV switchgear to get to the safety bus 23 from the transmission circuits. Pcwer frcm the transmission circuits (offsite power) is considered the preferred source of power which agrees with NRC criteria. There-fore, it is considered acceptable to place the undervoltage protection between the preferred source of power and the safety bus. The 2ko0V switchgear was chosen instead of the 23 bus for two reasons. First, it was decided that all plant equipment should te protected from any potential degrad-ed grid conditiens, not just the 23 tus. Second, the reference signal that trips the 2kCCV incoming line breaker should come from the 2hCOV bus and not from a 480V bus. Ite: 5 Table 1 does not show the setpoint of second level undervoltage relays as stated in Reference a. The value should have maximum and minimum limits to both voltage and time delay setpoints. Response to Ite: 5 Attachment II is the setting sheet used to calibrate the undervoltage and timing relays. The setting sheet gives the relay settings and acceptance criteria which is the same as maximu= and minimum limits. Item o Please supply the Technical Specification changes as called for in the Enclosure 2 of June 3,1977, letter from the !iRC.

Attachment I (Cont'd) 3 Pesponse to Iten 6 The Big Rock Point Technical Specifications are not in the format of the Model Technical Specifications; therefore, Consumers Power Ccepany vill submit appro-priate changes in the existing format. These che ges are currently being formu-lated and vill be subnitted as a Technical Specf. caticn chang.. request by February 1, 1981. Ite= 7 What is the worst case voltage drop between the,lE load buses /MCCs and the class lE motors? The Eig Rock Point analysis fails to consider the voltage drops. Respcnse to Item 7 Additional analysis was perforced to deternine the worst case voltage drop between Eus 23 and the safety-related motors connected to it. The vorst case proved to be the lOOHP Electric Fire Pump. With the grid voltage at 95 P.U., the voltage drop from the bus will be 1.5% While the motor is running and 6.1% during motor start-ing. The analysis also showed the worst voltage drop to various MOV's to be.12fi running and.24% startirg. References Consumers Power Company letter (D P Hoffman) to the NRC dated August 22, 1980 a. b. Consuners Power Ccmpany letter (W S Skibitsky) to the NEC (D L Ziemann) dated June 14, 1978

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