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Proposed Tech Spec Adding Degraded Voltage Protection & Upgrading of Loss of Voltage Protection.Voltage Profile Results for Electrical Arrangements Encl
	ML20054L543
Person / Time
Site:	Surry
Issue date:	06/30/1982
From:	; VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	;
Shared Package
ML18139B921	List: ML18139B920; ML18139B922; ML20054L539; ML20054L543;
References
	NUDOCS 8207080225
	Download: ML20054L543 (15)
	v • d • e

-. . - . ... . - - _ _ _

ATTACHMENT II This Attachment provides a draft of our proposed Technical Specifications as requested in the following NRC Question:

NRC Question 5: " Submit draf t proposed Technical Specifications changes to address limiting conditions for operation, testing, calibration, and surveillance requirements for the proposed undervoltage protection schemes. Also, a test is required to be included in the Technical Specifications to demonstrate the operability of .the automatic bypassing and auto-reinstatement of the undervoltage relays when the diesel generators are supplying the Class lE buses (see NRC letter dated June 3,1977)."

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i 8207080225 820630 PDR ADOCK 05000280 P ,

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TABLE 3.7-2 ENGINEERED SAFEGUARDS ACTION INSTRUMENT OPERATING CONDITIONS 1 2 3 4 OPERATOR ACTION IF CONDITIONS OF DEGREE COLUMN 1, OR 2 MIN. OF EXCEPT AS CONDI-OPERABLE REDUN- PERMISSIBLE BYPASS TIONED BY COLUMN 3 CHANNELS DANCY CONDITIONS CANNOT BE MET FUNCTIONAL UNIT 0 Restore inoperable

d. Station Blackout 2 Start Motor Driven Pump channel within 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months or be in hot shutdown within next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in cold shutdown within the follow-ing 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

1/ Pump Restore inoperable

e. Trip of Main Feedwater 1/ Pump Pumps channel within 48 Start Motor Pumps hours or be in hot shutdown within next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in cold shutdown within the follow-ing 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

4. LOSS OF POWER

a. 4.16 KV Emergency 2/ Bus 1/ Bus Bus Undervoltage s (Loss of Voltage) [

b. 4.16 KV Emergency 2/ Bus 1/ Bus os Bus Undervoltage (Grid Degraded Voltage)

- - . . m. . . . _ _ .

TABLE 3.7-4 .

ENGINEERED SAFETY FEATURE SYSTEM INITIATION LIMITS INSTRUMENT SETTING CHANNEL ACTION SETTING LIMIT NO. FUNCTIONAL UNIT

6. AUXILIARY FEEDWATER Steam Generator Water Level Low-Low Aux. Feedwater Initiation g5%narrowrange a.

S/G Blowdown Isolation

b. RCP Undervoltage Aux. Feedwater Initiation 2t70% nominal Aux. Feedwater Initiation All S.I. setpoints

c. Safety Injection Aux. Feedwater Initiation j;46.7% nominal

d. Station Blackout Aux. Feedwater Initiation N.A.

e. Main Feedwater Pump Trip

7. LOSS OF POWER 1

a. 4.16 KV Emergency Bus Emergency Bus 75+g% volts with a Undervoltage Seperation and Diesel start 2+5,-0.1 second time (Loss of Voltage) delay 4.16 KV Emergency Bus Emergency Bus 90*

.0% volts with a b.

Undervoltage Seperation and Diesel start 60+3.0 second (Degraded Voltage) time delay

, (Non CLS, Non SI) i 7,+.35 second

) time delay I

(CLS or SI Conditions) vl G

t

_ . . _ _ _ _ . _ _ - . _ . _ . . _ . _ - .. . ._ _. . . _ . . _ _ . . _ .- . .m -- __ _ _ _ . ._ _ _ _ _ .__~.m ._ _ _ _ _ . . .

' TABLE 4.1-1 (Continued) .

j CHANNEL CHECK CALIBRATE TEST REMARKS DESCRIPTION i

35. LOSS OF POWER I a. 4.16 KV Emergency Bus N.A. R H I undervoltage I (Loss of voltage)

b. 4.16 KV Emergency Bus N.A. R M undervoltage .

1 (Degraded voltage) 1 l

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ATTACHMENT III This Attachment addresses the following NRC Questions:

NRC Question 6: "Are the following viable source connections?

(a) A single 500/230/36.5 KV autotransformitr supplying both 34.5 KV buses 5 and 6 (i.e., breal:er LT22 open and LT12 closed (or vice versa), T562 closed and both L402-5 and L402-6 open).

(b) The 230/36.5 KV transformer supplying both 34.5 buses 5 and 6 (i.e., breakers LTl2 and LT22 open, T562 closed and L402-5 closed and L402-6 open (or vice versa)).

If these are not viable connections, are there interlocks to prevent these breaker alignments?"

i NRC Question 7 "Are there interlocks to prevent closure of both the 34.5 KV low side breakers on the 230/36.5 KV transformer?"

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As discussed in our June 11, 1982 letter to you, Serial No. 317, the three arrangements discussed in Questions 6 and 7 are physically possible arrangements. There are no electrical interlocks which prevent these arrangements. An arrangement with the 230/36.5KV transfomer supplying both 34.5KV buses at the same time, through L402-5 and L402-6 with T562 open, is the most probable arrangement, since it may occur automatically. The arrangements discussed in Question 6 require manual closure of the disconnect switches on both sides of T562 prior to implementation of the arrangements.

As we originally stated in our May 20, 1982 telephone conference with Messrs.

D. Neighbors, R. Trevatte and J. Sealan, we believe the probability of two transfomer f ailures combined with an SI or CLS is extremely small. We, therefore, did not analyze these scenarios. The following scenarios do include these arrangements and are provided in response to your request.

Case I, Job Numbers 1459 and 2734, analyzes the 230/36.5KV transformer feeding both 34.5KV buses, regardless of which breaker alignment is in use.

The scenario studied is a Unit 2 CLS assuming Unit 2 station service loads transfer to the Reserve Station Service Transfomers (RSST's) at the instant the CLS occurs. Unit 1 is assumed to trip and transfer its station service loads to the RSST's 60 seconds after the Unit 2 CLS.

In Case I, the 4KV motors have adequate voltage to accelerate at T=0 seconds. The minimtsn required 480V load center voltage at bus 2H is 70.9% to start the Containment Spray Pump and 72.0% to start the Low Head Safety Injection Pump. At 480V bus 2J the voltage requirements are 73.3% and 73.5%

to start the Containment Spray and Low Head Safety Injection Pumps, re spectively. At T=0 seconds, the 2H and 2J 480V bus voltages are 70.2% and 70.5%, respectively. Since two Charging Pumps were modeled as starting when one would normally be running, these voltages are lower than actually expected for this scenario. With acceleration of the 4KV Charging Pumps and an instantaneous signal to the RSST's load tap changer (LTC) to begin correction, the voltage profile will improve to enable the starting of the 480V motors.

MOV's rated at 368V starting will receive adequata starting voltage in sufficient time to ensure their overload heaters will not operate. At T=7 seconds, the LTC taps will be advanced by another step and spurious separation will not occur (the degraded voltage setpoint during accident conditions is 90% voltage at 7 seconds). Analysis at T=59 seconds is equivalent to a steady state condition for single unit loading to the RSST's. The voltages at this time are acceptable. Analysis of the steady state voltages at T= infinity, which represents the effects of two unit loading on the RSST's, indicates unacceptably im voltages on 480V buses lH1, IJ1, 2H, 2H1, 2J and 2J1.

Case II, uob Numbers 1609 and 3589, analyzes a 500/230/36.5KV autotransfomer feeding both 34.5KV buses, irregardless of which breaker alignment is in use. The scenario analyzed is the same as in Case. I. The resultant voltages are approximately 1% - 2.5% lower than those in Case I during motor starting and 2.5% - 3% lower at steady state. These are unacceptable results.

b "C /2 g]/M.

With reference to Technical Specification Section 3.16, each 500/230/36.5KV autotransformer and the 230/36.5KV transformer is considered to be a primary source which can supply offsite power to a 34.5KV bus. The intent of item B.2 is to maintain separate offsite supplies to each 34.5KV bus. With only one of the above mentioned transformers supplying both 34.5KV buses, both units may be operated for seven days, provided the dependable alternate source can be operable within eight hours. This restriction sufficiently controls operation with a single transformer supplying both 34.5KV buses. In view of the low probability of these events, modifications are not required to prevent this operating arrangement.

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