ML20198P657
| ML20198P657 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 11/04/1997 |
| From: | DUQUESNE LIGHT CO. |
| To: | |
| Shared Package | |
| ML20198P653 | List: |
| References | |
| NUDOCS 9711100071 | |
| Download: ML20198P657 (7) | |
Text
.
ATTACHMENT A l
Beaver Valley Power Station, Unit No. 1 Proposed Technical Specification Change No. 243 m
The following is a list of the affected pages:
Affected Page:
3/4 3-24 p
9711100071 971104 PDR A00CK 05000334 p
TABLE 3.3-4 (Lontinued)
ENGINEERED SAFETY FEATURE ACTUATION SYSTEM INSTRUMENTATION TRIP SETPOINTS o.
- o FUNCTIONAL UNIT TRIP SETPOINT ALLOWABLE VALUES Y
On On 4.
STEAM LINE ISOLATION a.
Manual Not Applicable Not Applicable b.
Automatic Actuation Logic Not Applicable Not Applicable c.
Containment Pressure--
$ 3.0 psig s 3.9 psig l
Intermediate-High-High d.
Steamline Pressure-Low 2 500 psig steam 2 488 psig steam l
line pressure line pressure e.
High Negative Steam Pressure
$ 100 psi with a time
$ 127 psi with a time l
Rate constant 2 50 seconds constant 2 50 seconds
- 5. TURBINE TRIP AND FEEDWATER ISOLATION a.
St eam Generator Water Level 5 75% of parrow range s 76.9% of narr>w range l
High-High instrument span each instrument span each steLa generator steam generator 6.
LOSS OF POWER a.
1.
4.16kv Emergency Bus 2 75% of nominal bus 2 73% of nominal bus l
Undervoltage (Loss of Voltage) voltage with a 1 i 0.1 voltage with a 1 1 0.1 (Trip Feed) se.cond time delay second time delay
___.-n,,
2 2t - 1
-h-8-14-of nc::inal buc l
375y. o8 rwm:n=2 cyc! cc 2.
4.16kv Emergency Bus 1 bus, vo%ge esj tagc 274 y. af enal t>05 (Start Diesel) swx ca secana time aesag%),
v m a a:sn,t x o.4 g ee,e s o n e 4 1ay a
oq re ta 6 8mes),
csacio ses oo:r_38.aq retag e c
acar.
b.
4.16kv Emergency Bus
_ 90% of hW inal buP W 8 of nominal us Undervoltage (Degraded Voltage) voltage with a 90 1 5 voltage with a 90 i 5 second time delay second time delay l
480v Emergency Bus Undervoltage 2 90% of nominal bus 2 88% of nominal bus c.
(Degraded Voltage) voltage with a 90 1 5 voltage with a 90 1 5 seccnd time delay second time delay BEAVER VALLEY - UNIT 1 3/4-3-24 Amendment No..MG-
@tofesttlNedthf
ATTACHMENT B Beaver Valley Power Station, Unit No. 1 Proposed Technical Specification Change No. 243 4.16 KV EMERGENCY BUS UNDERVOLTAGE (START DIESEL) SETPOINT
~
e A.
DESCRIPTION OF AMENDMENT REQUEST The proposed amendment would modify Engineered Safety Feature Actuation System (ESFAS)
Instrumentation Trip Setpoint, Table 3.3-4, Item 6.a.2 "4.16 Kv Emergency Bus (Start Diesel) by changing the trip setpoint to 2 75 percent of nominal bus voltage with a time delay of < 0.9 seconds, which includes the auxiliary relay times.
The allowable value would also b2 changed to 2 74 percent of nominal bus voltage with a time dulay of <
0.9 seconds, which also includes the auxiliary relay times.
B.
BACKGROUND The ESFAS initiates necessary safety systems, based on the values of selected unit parameters, to protect against violating core design limits and the Reactor Coolant System (RCS) pressure
- boundary, and '. o mitigate accidents.
Technical Specification (TS)
Amendment No.
40 incorporated Item 6,
" Loss of Power" setpoints and allowable values into Table 3.3-4 in response to an NRC generic letter dated June 3,
1977, concerning <*egraded grid voltage protection.
Amendment No.
40 provided i setpoint of 2 83% with a 12 cycle time delay for Item 6.a.2 and Amendment No. 155 added an Allowable Value of 2 81% of nominal bus voltage.
As noted in Amendment No.
40, the setpoint value was selected based on an evaluation of the system loads to meet the generic letter criteria.
Amendment No. 155 provided the allowable value based on a
reanalysis performed to update the setpoint methodology to the same methodology used in determining the Unit 2 protection setpoints.
The methodology used is described in WCAP-11419
" Westinghouse Setpoint Methodology for Prctection Systems, Beaver Valley Unit 1" (proprietary) and WCAP-11420.
C.
JUSTIFICATION An evaluation of the emergency bus voltages found that, during Reactor Coolant Pump (RCP) start and occasionally during fast bus transfer, the Emergency Diesel Generator (EDG) starts.
This is an undesired response to theue events and occurs in response to a 4.16 KV emergency bus voltage dip below the TS setpoint value during the transient.
Therefore, to minimize unwanted future EDG starts when an RCP or other large motor is started or a fast bus transfer occurs, a reduced retpoint and allowable value have been developed.
The new settings have been selected to account for c
tolerance and provide margin.
In addition, margin has been added to the time delay of < 0.9 seconds, which includes the auxiliary relay times and was selected to be slightly lower than the feeder undervoltage relay setting (1.0 1 0.1 second).
The proposed
- setpoint, allowable value and time delay are similar to the
ATTACIIMENT B, c0ntinucd
- Propond T chnical Sp:cification Changa No. 243 Page 2 Unit 2 values and provide sufficient margin to protect the equipment connected to the bus and reduce undesired EDG starts.
D.
SAFETY ANALYSIS The 4.16 KV emergency bus diesel start is an anticipatory function to naintain power to equipment connected to the emergency bus on a loss of power to the bus.
The proposed changes to the setpcint, allowable value and time delay do not change the values assumed in the safety analysis and do not affect the degraded grid voltage protection requirements for Class 1E power systems.
The UFSAR does not take credit for this function.
The WCAP me.thodology was used in determi'11ng the setpoint and allowable value voltages.
These setting changes will minimize the EDG starts due to voltage dropa when a large motor is started or a fast bus transfer occurs.
In response to reduced voltage, the heat generated by an increase in motor current will be less than the heat generated during motor starting.
Typically, during motor starting, the inrush current lasts for 60% to 70% of the starting time.
Large motor starting times vary from approximately 1 to 15 seconds (i.e.,
Reactor Coolant Pump takes 14.5 seconds at 4160 volts to reach full speed).
The results of analysis 8700-E-271 shows that bus voltages may dip below the 74% allowable value setpoint and then recover to the pick-up setpoint in a worst case scenario of 0.6 seconds without stalling motors.
All the equipment connected to the 4.16 KV emergency buses will operate the same as before the setting changes.
The performance of the safety system will remain unchanged.
The lower voltage setting and the longer time delay will have no adverse effect on the operation of the equipment fed from the bus when a large motor is started or fast bus transfer occurs.
This change will reduce the wear on the EDGs and includes sufficient margin to minimize undesirable equipment actuations during RCP start and fast bus transfer operations.
The revised setpoint and time delay allow normal voltage drops to occur during expected plant operations without causing any thernal damage to safety-related equipment.
In addition, tha revised setpoint and time delay are sufficient to protect safety-related equipment from a sustained degradad voltage condition.
Therefore, the proposed changes are considered safe since undesirable EDG starts are minimized, no conditions are introduced that would damage safety-related equipment and safety-related equipment is protected from a degraded voltage condition.
E.
NO SIGNIFICANT HAZARDS EVALUATION The no significant hazard considerations involved with the proposed amendment have been evaluated, focusing on the three standards set forth in 10 CFR 50.92(c) as quoted below:
B-2
. ATTACHMENT B, continusd Proposed Technical'Spacification Change No. 243 Page 3 The Commission may make a final determination, pursuant to the procedures in paragraph 50.91, that a proposed amendment to an operating license for a
facility licensed under paragraph 50.21(b) or paragraph 50.22 or for a
testing facility involves no significant hazards consideration, if operation of the facility in accordance with the proposed amendment would not:
(1)
Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2)
Create the possibility of a new or different kind of accident from any accident previously evaluated; or (3)
Involve a significant reduction
' a margin of safety.
The following evaluation is provided for the no significant hazards consideration standards.
1.
Does the change involve a
significant increase in the probability or consequences of an accident previously evaluated?
The proposed change replaces the current Engineered Safety Feature setpoint, allowable value and delay time for the diesel generator start on loss of power function.
An analysis has been performed to develop the new values to minimize the diesel generator starts when a Reactor Coolant Pump (RCP) is being started or a fast bus transfer occurs.
The heat = generated by an increase in - motor current, in response to reduced voltage, will be less than the heat generated during motor starting.
The analysis results show that bus voltages may dip below the allowable setpoint value and then recover to the pick-up setpoint within the proposed delay time without stalling motors.
The proposed change does not affect the design and reliability of any plant equipment; therefore, the probability af occurrence of a previously evaluated accident is not increased.
The operation of the plant will not be changed as a result of this proposed amendment, except-that fewer diesel generator starts will be initiated.
This function anticipates the loss of voltage to protect
-equipment connected to the 4.16 Kv emergency bus.
The UFSAR accident analyses do not take credit for this function; therefore, the consequences of an accident previously evaluated is not increased.
l l
B-3
ATTACHMENT B, continued Propoacd Technical Spscification Chango No. 243 Page 4 2.
Does the change create the possibility of a new or different kind of accident from any accident previously evaluated?
The proposed change to the trip setpoint, allowable value and delay time will continue to ensure that the safety-related equipment connected to the emergency bus is adequately protected from a low voltage condition.
These setting changes will minimi::e the diesel generator starts due to voltage drops when an RCP is started or a fast bus transfer occurs.
The new setpoint and time delay allow normal voltage drops to occur during expected plant operations without causing any thermal damage to safety-related equipment.
The performance of the safety system will remain unchanged and will not alter any plant equipment, performance requirements or safety analysis.
Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
3.
Does the change involve a significant reduction in a margin of safety?
The proposed change does not involve a significant reduction in a margin of safety since an analysis has been performed to verify that safety-related equipment connected to the emergency bus is adequately protected from a low voltage condition with the proposed settings.
The proposed changes do not affect the UFSAR design bases, accident assumptions, or technical specification bases.
In addition, the proposed changes do not affect release limits, monitoring equipment or plant operating practices.
Therefore, the proposed change will not involve a significant reduction in a margin of safety.
F.
NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION Based on the considerations expressed above, it is concluded that the activities associated with this license amendment request satisfy the no significant hazards consideration standards of 10 CFR 50.92(c)
- and, accordingly, a
no significant hazards consideration finding is justified.
G.
ENVIRONMENTAL CONSIDERATION The proposed amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
It has been determined that the proposed amendment involves no significant increase in the amounts, and no significant change in the types of any effluents that may be released offsite, and that there is no significant incmase in individual or cumulative occupational radiation exposure.
Accordincly, the proposed amendment meets the B-4
- . ATTACHMENT B, continutd Proposed Technical Spacification-Chango No. 243 Page 5 eligibility criteria for categorical exclusion set forth in 10 CFR
- 51. 2 2 (c) (9).
Pursuant to 10 CFR 51.22 (b) no environmental impact statement' or environmental assessment need be prepared in connection with the issuance of this proposed amendment.
H.
UFSAR CHANGES None i
B-5 l
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