ML18044A583

Forwards Response to 790606 Ltr Requesting Addl Info Re Degraded Grid Voltage

ML18044A583
Person / Time
Site:	Palisades
Issue date:	02/27/1980
From:	Frost S CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	Ziemann D Office of Nuclear Reactor Regulation
References
TASK-08-01.A, TASK-8-1.A, TASK-RR NUDOCS 8003030304
Download: ML18044A583 (6)

Text

consumers Power company General Offices: 212 West Michigan Avenue, Jackson, Michigan 49201 * (517) 788-0550 February 27, 1980 Director, Nucle~r Re~ctor Regulation Att Mr Dennis L Ziemann, Chief Operating Reactors Branch No 2 US Nuclear Regulatory Commissi.on Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - RESPONSE TO ADDITIONAL INFORMATION FOR DEGRADED GRID VOLTAGE By letter dated June 3, 1977 from Mr A Schwencer (NRC) to Mr D A Bixel (CP Co), Consumers Power Company was informed that the NRC was reviewing the on-site emergency power systems of all operating nuclear power facilities.

This review was to asses~ the susceptibility of safety-related electrical equipment to (1) sustained degraded voltage conditions at the off-site power source~ and (2) interaction bet~e~n the off-site and on-site emergency.powe~

systems.

Specifically, the NRC requested that Consumers Power Company compare the current design of the emergency power systems with the staff's position stated in the enclosure of the June 3, 1977 letter and:

1. Propose plant modifications, as necessary, to meet the staff'. s positions, or

2. Provide a detailed a~alysis which shows that the Palisades Plant design has equivalent capabilities and protective features, and

3. Model certain Technical Specifications, consistent with the staff positions as in Enclosure 2 of the June 3, 1977 letter.

By letter dated July 28, 1977, Consumers Power Company responded to the NRC's Jur.:.J;~ 3, 1977 letter and on Q,ctober 2, 1'*J77 we revised our July 28, 1977 letter by deleting a proposed change to the plant.Technical Specifications.

Specifically, Position lf of the October 2, 1977 response stated ~hat detrimental minimum voltage .levels will anly occur <luring a shutdown Diode and, therefore, no limiting of operating conditions are necessary.

2 The NRC Letter dated June 6, 1979 from Mr D L Ziemann (NRC) to Mr D A Bixel (CP Co) informed Consumers Power Company that, based on NRC review, additional information was needed.

I Additional information is attached.

Steven R Frost Palisades Licensing Engineer CC JGKeppler, USNRC

1 REQUEST FOR ADDITIONAL INFORMATION Palisades Plant Degraded Grid Voltage Item 1 In your response to position if, you state that detrimental minimum voltage levels will on+y occur during a shutdown mode and, therefore, no limiting conditions of operation are necessary. It is our position that a reactor trip while the grid is in a degraded state would be a situation in which the protective relays would have to operate correctly and that Technical Specifications for voltage protection are necessary. Therefore, please submit Technical Spedfications changes to comply with our June 3, 1977 letter.

These changes should comply as close as possible to the.Model Technical Specifications (MTS) and should also include the lim{tin~ conditi~ns for operation, surveillance requirements, and nominal set points with minimum and

• maximum limits for first level voltage protection (loss of voltage) as shown in the MTS.

Response to Item 1 Technical Specifications and/or surveillance testing changes for the modifications for the degraded grid voltage will be completed 30 days after plant start-up of the present refueling outage. Due to the present workload at the plant with the TMI modifications.and the revision/review of plant procedures, an earlier time schedule w6uld be extremely difficul~ to meet.

Item 2 Please explain why your choice of a 3/3 coincident logic is acceptable from a safety standpoint (as contrasted to a 2/3 coincident scheme). Schematics of the proposed relaying circuits and types of relays being used are also requested.

Response to Item 2 A Bechtel review has indicated that the 3 out of 3 logic is to be pref erred for the following reasons:

1. Historically the off-site (grid) power sources have been known to have a high degree of availability and reliability. It is, therefore, necessary to ensure that the high level of availability is not degraded due to unintentional trips such as might be caused due to PT fuse blowing.

Three out of 3 logic prevents the maloperation of the proposed undervoltage scheme when a single fuse blows out in the 120 V a-c potential transformer secondary circuit. Such maloperation will lead to unwanted trip of the off-site power source ACBs and the transfer of the safety-related buses to the on-site emergency diesel generators.

2

2. The existing undervoltage protection scheme for the 2400 V safety-related buses 1-C and 1-D utilizes 3 qut of 3 logic. To be consistent, it is preferable to use 3 out of 3 logic for the proposed addition, also.

A description of the types of relays being used is as follows:

1. Adjustable definite time delay (0.1 to 1 second) undervoltage relays with high pickup to drop-out ratio (guaranteed va~ue not to exceed 103.5),

frequency compensated with transient immunity, suitable for use in potential transformer secondary circuits rated 120 volts a-c. Control voltage shall be 125 volts d-c. The relay setting ranges 60 volts to 110 volts. In combination with the front tap settings and internal potentiometer, it shall be suitable for continuous adjustments in this setting range. The output contacis shall be self-reset and rated for 125 volts d-c, 5 amps, continuous duty, relay type No ITE-27D (by Gould !TE).

Buyer's tag number for three (3) relays shall be 127- 7. and for the remaining relays the tag nU1I1ber shall be 127-8.

2.  !TE extender board assembli_es for use with the undervoltage relays of Item 1 above, !TE catalog No 200X0018 (by Gould !TE).

Buyer's tag numbers for these two extender board assemblies shall be 127-7 and 127-8.

3. Timing relays with adjustable delay on pickup and with fast resetting time. Setting ranges 0 to 10 seconds. Control voltage 125 volts d-c.

Furnished with two Form C output contacts. Buyer's tag numbers for these two timing relays shall be 162-153 and 162-154. Relay type ITE-62K (by Gould !TE).

The enclosed Figure 1 is the proposed relaying circuit scheme to be used at the Palisades Plant.

Item 3 Will the proposed relays and other components of the circuit be seismically and environmentally qualified?

Response to Item 3 All the above relays, Items 1 and 3, will be used on nuclear plant safety-

.related circuits and shall be capable of meeting the test requirements per IEEE-STD-501 (1978) - Seismic Testing of Protective Relays. These relays will be located in a controlled atmosphere and, therefore, no special qualification is required.

Item 4 Has an analysis been performed to determine ff the proposed 6-second time delay is of long enough duration to take into account the starting time and consequential voltage drops from large motors on the bus?

y 3

An analysis has. been performed and based on this analysis, frequent spurious shedding fr9m the off-site source will not occur under normal worse case conditions and, therefore, modifications involving sequential loading or partial shedding are not necessary.

The plant's second level of undervoltage protection is designed to protect the ESF loads from sustained degraded voltage (approximately equal to .91 pu to

.70 pu} in excess of 6.5 seconds.

NOTES' THE LOGIC SHOWN IS FOR BUS 1-C.

[QUIPMENT NUMBERS FOR BUS 1-D I 1.5 SEC ARE SHOWN IN PARENTHESIS. j, 2 FOR DETAILS REFER TO LQC>IC AND SCHEMATIC DWGS E-11 51°1 I &E*IZI D 162*107

3. FOR DETAILS ON DIESEL GHnRA*

(1&2 *213) TOR START IN NORMAL/ TRANSFER CUTOUT MODES 5££ LOGIC ANO SCUEMATIC DWC.5. *f*l7 SH Z & f* 136 STA. PWR BKR l52"-I05 4. FOi? DETAILS ON DIESEL GENERA-TRIP OPEN (152-203) TOR TRIP/CLOSE SEE LDC.IC AND STA. PWR ST.UPPWR BKR '152-IOf SCHEMATIC OWGS £*1' AND BKR 152-10 O_P_E_N_ _ _ _(l_5_2- ..Z-O_Z_)-------+i~ E

• 139 SH. I.

(152*203)

D.C.. DIFF. CLOSl OG J OVERU>AD BKR 152*107 LDC.II.OUT t---f)(f--------'"i (1 ~2"213)

RE:LAV 1e.1o* 101 PRE LOAD (1!>1.o*.2./J)

SH£.O UND£~VOLTA6E eELAY RELAY MOOll=°ICATIOAJS SltCl'WAI TUUS:

144* DI LAT£ST CµAJJGCS TO (144*02) UV RELAY MOOll="ICATIOIJS INITIATE SHO\..IA/ THUS:~

LOAD SHEDDINC. DG BKR

'4-IOB, 94*1109A,94*1109B CLO'OE

[ 1i4 *211, 94*121JA, 9'1*12138) RELAY5 10&-DI UllDERVOL T.

LOA 0 1------t (IOl..Cll)

SHEDDING 1~7X *II. IZ7l<.-12 (127X*21.127X*22)

EE NOT£ 3 STAeT or..

0.5 SEC 127*2*XI \

( 127*2*X2 I J--------t---+-----+------ 1- / & 1*2 j I

x- y 30b 0-1, 306 D*Z, JOI> D* 3, lot. 0*4 IC BUS UVL)7-7Y-Z (I 27*9) ~--+----

(PffOF05£D) a.s sec. 127* 7-X I

~*

121-1-xz 127-S*X I NNUIJ BUS

( 127 *B *X2 ~-+---r- I( ANDblll NOERVOLT TRIP STU X-Y 8Kl1 152*10/,

STARTUP SOURCE _Y_--'-z_ _ _ _ f-9--+-..+---l (152*202)

BECHTEL uv121-s z-x AU ARBOR. lllCHIGU (IZ7*') - - - - - PALISADES PLANT CONSUMERS POWER COMPANY GWO 8538 ANIJUN. STANDBY START UNDERVOL TAGE. MODI -IC TIO 5 PWR NOT SAFE TY AVAILABLE 6ZL/SIS SIS

('2R/St5) .;:___ _ _ _--!

LOADS Ct.:T. NQ I SIS-XI, 515-X3, 515-XS & 515*X7 LOGIC DIAGRAM 2.'ll<V SAFETY BUSES I*( .l 1*0 UIJDERVOLTAG( PROTECTIOt.1 l

A I (CKT 1'1~2 SIS*X2, SIS*X4, SIS*X6 & SIS*llB)

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