ML19344D585
| ML19344D585 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 03/31/1980 |
| From: | Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-79-27, NUDOCS 8004250065 | |
| Download: ML19344D585 (11) | |
Text
v 4
PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 JOSEPH W. G ALLAGH ER stsevmc enoovcv o'= oseantessut (2151841-5003 March 31, 1980 IE Bulletin 79-27 Mr. Boyce H.
Grier, Director Office of Inspection & Enforcement Region I US Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406
Dear Mr. Grier:
This letter is a follow-up response to our letter of February 29, 1980 on Bulletin 79-27.
This Bulletin requires a review of buses supplying power to instrumentation and control systems which could affect the ability to achieve a cold shutdown condition.
The " Actions to be Taken by Licensees" are repeated for those items which had an incomplete response in our original submittal.
Actions to Be Taken h Licensees 1.
Review the class-1-E and non-class 1-E buses supplying power to safety and non-safety related instrumentation and control systems which could affect the ability to achieve a cold shutdown condition using existing procedures or procedures developed under item 2 below.
For each bus:
a) identify and review the alarm and/or indication provided in the control room to alert the operator to the loss of power to the bus, b) identify the instrument and control system loads connected to the bus and evaluate the effects of loss o f power to these loads including the ability to achieve a cold shutdown condition.
I 80042506 6
t Mr. Boyce H.
Grior Pago 2 c) describe any proposed design modifications resulting from these reviews and evaluations, and your proposed schedule for implementing those modifications.
Response
t The class 1-E and non-class 1-E buses (distribution panels) supplying power to safety and non-safety related instrumentation and control systems which could affect the ability to achieve a cold shutdown using existing procedures have been reviewed.
l a)
The alarms that indicate a loss of power to the instrument buses are identified in Table I.
Alarms were identified that directly indicate a loss of power to the instrument bus l
or to a system.
If such an alarm was not available, a process alarm that is caused by the loss of power was identified.
The DC distribution panels that feed the controls used for cold shutdown are provided with low voltage alarms.
Additionally, each train of system logic for the sa fe shutdown equipment is also provided with power failure l
alarms so that the loss of control capability would be known to the operators.
r i
b)
An evaluation o f the e f fects of loss of power to the contrcl system loads was addressed in our~ original response.
The instruments in the control room which provide information to the operator to achieve a cold shutdown have i
been identified and are fed from the buses listed in Table II.
An analysis has been done to determine if, for the loss t
of a power feed to each instrument identified, there is another instrument available that is fed from another independent bus and monitors the same parameter or an alternate method is available for determining the missing variable.
The instrument parameters identified and the analysis for loss of power to their associated buses are 3
shown in Table III.
c)
The following modifications to improve instrumentation are in the design stage and will provide redundant instruments in the control room:
i Instrument Parameter MOD Completion Date
- Torus Temperature 6/1/81 Torus Level (Wide Range) 1/1/81 Drywell Pressure (Wide Range) 1/1/81 Containment Radiation Monitors 1/1/81 Main Stack-Radiation Monitors 1/1/81 Reactor Building Vent Radiation Monitors 1/1/81
~
Mr. B o y c o 11. Crier Pago 3 Relief Valve Monitors 1/1/81
- Unless precluded by equipment or material unavailability.
The following recently identified modifications will be incorporated in order to improve instrument reliability:
1)
Presently the instrument supply cabinet (C144) is fed from two parallel feeds, Y3734 and Y3315.
Since both of these Y-Panels
- r. r e fed from the same MCC, the Y3734 feed to C144 will be moved to another Y-Panel.
It is expected that this change will be completed by 1/1/81 on Unit 2 and 6/1/81 on Unit 3.
2)
Presently there are two instrument loops for the Torus Pool Level (Harrow Range).
One loop is fed from Panel Y33 and the other is fed from Panel Y37.
- However, the indicating recorder on the Panel Y37 loop is fed from Panel Y33, thus, if Panel Y33 is lost, both instrument loop indicators in the control room are lost.
In order to resolve this problem, these feeds will be interchanged so that Panel Y33 feeds one loop and recording indicator and Panel Y37 feeds the other loop and indicator.
It is expected that this change will be completed by 1/1/81 on Unit 2 and 6/1/81 on Unit 3.
Actions to be T& ken By Licensees 2.
Prepare emergency procedures or review' existing ones that will be used by control room operators, including procedures required to achieve a cold shutdown condition....
Describe any proposed design modification or administrative controls to be implemented resulting from these procedures, and your proposed schedule for implementing the changes.
Response
As indicated in our original response, a new procedure is being written for the loss of the Y50 non-class 1-E uninterruptible AC distribution panel.
It is expected that this new procedure will be complete by 6/1/80.
There are no other procedures being developed as a result of this review and no additional design modifications other than those identified in response to item 1.
Very truly yours, hyBLL~
l Attachment U
cc:
US Nuclear Regulatory Commission Office of Inspection & Enforcement Division of Reactor Operations Inspection Washington, DC 20555
TABLE I ALARMS COMMENTS YO3 -
2(3) Vent Exhaust Stack Radiation The alarm comes from Monitor B the failure of the radiation monitors that are fed from this supply. These are the only instruments fed from this panel that are used for safe shutdown purposes.
Y33 -
Turbine Supervisory Instru-24V DC t o e <* s instru-mentation Voltage Loss Trip ment power supply 24V DC Instrument Power on con:rol board C144 Standby Source Y34 -
High Area Temp. Monitor Power Failure Y35 -
2 (3) Vent Exhaust Stack Radiation Same as Comment on YO3 Monitor A Y37 -
24V DC Instrument Power on 24V DC feeds instru-Standby Source ment power supply control board C144 Y50 -
A Reactor Feed Pump Turbine Inverter trouble alarm Failure is not applicable if B Reactor Feed Pump Turbine YSO panel is being Failure supplied from the C Reactor Feed Pump Turbine external maintenance Failure feed.
Inverter Trouble YO2A -
Standby Gas Treatment Negative This alarm is not Plenum Differential Pressure Low currently installed.
It is a proposed addition and is expected to be installed by 1/1/81.
Y15 -
A Recirc. Speed Control Signal Fail The "A" Recirculation A Recire. Fluid Drive Scoop Tube MG controls and instru-Brake On ments are the only A Recire Fluid Drive Scoop Tube controls and instruments Lock fed from this panel that could be used for 1-
TABLE I ALARMS COMMENTS purposes of safe shutdown.
Y22 -
B Recirc Speed Control Signal Fail The "B" Recirculation B Recirc Fluid Drive Scoop Tube MC controls and instru-Brake On ments are the only B Recirc Fluid Drive Scoop Tube controls and instruments Lock fed from this panel that could be used for purposes of safe shutdown <
Y30 -
E124 (E134) Motor Control Center The alarm comes from a Feeder Breaker Trip and loss of the MCC that feedC Y32 -
E424 (E434) Motor Control Center the Y panel. If the Feeder Breaker Trip MCC remains energized, there is no direct alarm to indicate loss of the Y panel. However, modifications to the torus temperature instru-ments, which are the only instruments fed from this panel that could be used for purposes of safe shutdown, will provide redundant instruments fed from separate buses that have either a direct or process alarm due to loss of power.
RPS "A"
(C183A)
The C183 A&B panels and have indication in RPS "B"
(C183B) the control room to show that power is available to the distribution buses.
These panels are the Reactor Protection Systemf Primary Containment Isolation System Feeds.
The operator would know instantly if either of these two feeds.
TABLE I ALARMS COMMENTS become unavailable due to a half scram and a Group I half isolation.
There is one alternate feed available to these two panela that can be manuclly transferred in the control room to either of the two distribution buses.
AD25 -
RCIC Inverter Failure Refer to Note J of Table III for dis-cussion on RCIC system.
BD25 HPCI Invarter Power Failure Refer to Note H of Table III for dis-cussion on HPCI system.
D23 System I RHR Logic Power Fail (RCIC) Inverter Failure ECCS Trip Units Card Out of File or Power Failure 2(3)C DC Power Panel Lo Voltage D24 Blowdown Control Power Failure ECCS Trip Units Card Out of File or Power Failure 2(3)D - DC Power Panel Lo Voltage AD45 24/48 Volt Bus 2E-2G (3E-3G)
Radiation Monitoring Trouble BD45 24/48 Volt Bus 2F-2H (3F-3H)
Radiation Monitoring Trouble l
3-i l
1.
TABLE II
- Bus Voltage _
Bus Feed YO3 120V AC "D"
Diesel Gen.
Y30 120V AC "A" Diesel Gen.
Y32 120V AC "D"
Diesel Gen.
Y33 120V AC "A"
Diesel Gen.
Y34 120V AC "B"
Diesel Gen.
Y35 120V AC "C"
Diesel Gen.
Y37 120V AC "A"
Diesel Gen.
Y50 120V AC Inverter 6 Alternate Feed is "A"
Diesel YO2A 120V AC Unit Auxiliary Buses Y15 120V AC Unit Auxiliary Buses Y22 120V AC Unit Auxiliary Buses RPS "A"
RPS "B"
AD 25 125V DC 125V Battery AD01 BD 25 125V DC 125V Battery BD01 D23 125V DC 125V Battery CD01 D24 125V DC 125V Battery DD01 AD45 24V DC 24V Batteries A& CD27 BD45 24V DC 24V Batteries A& DD27
- Bus feeding instruments in control room which provide information to the operator to achieve a cold shutdown.
TABLE III Instrument Parameter Evaluation Bus Reactor Level See Note A Y50,Y33,D23, D24, BD25 Reactor Pressure See Note A Y50,BD25 Vessel Temperature See Note C Y34, Y33 Torus Level (Narrow See Note D Y33, Y37 Range)
Torus Level (Wide Range)
See Notes B&E Y33, Y37 Torus Temperature See Note B Y50, Y30, Y32 Drywell Pressure See Note A Y33, Y34 Drywell Temperature See Note C Y34 Rod Position Information See Note M YSO System Neutron Monitoring See Note A RPS "A",
RPS "B",
YSO, AD45, BD45 Standby Liquid Control Level See Note F Y33 Standby Liq. Control Pressure See Note F Y33 HPCI Instrumentation See Note H BD25 RCIC Instrumentation See Note J AD25 Core Spray Instrumentation See Note K Y33 RHR Instrumentation See Note L YSO, Y33, Y34 HPSW Instrumentation See Note E Y33, Y37 SBGT Flow, Filter DP See Notes F&G YO2A Emergency Cooling Twr.
See Note E Y33, Y37 Radiation Monitoring:
Reactor Bldg. Vents See Notes A&B YO3, Y35 i
Control room See Note A YO3, Y35 Main Stack See Note B Y50, AD45 Condenser Vacuum See Note F Y34 Condensate Storage Tank Lev. See Note E Y33, Y37 Recirculation Pumps,MG sets:
Flow See Note A Y33, RPS"A",RPS"B" Speed Controls See Note F Y15, Y22 Temperature See Note F Y33 Instrument Air Pressure See Note E Y33, Y37 Turbine Bldg. Cooling Water Temperature See Note F Y34 Reactor. Bldg. Cooling Water Temperature See Note F Y34 Service Water Pressure See Note E Y33, Y37 Relief Valves See Note B Y33 5-
Notes for Tchle III t
A.
There is more than one instrument in the control room to monitor this parameter and these instruments are not all fed from the l
same bus; thus, the loss of one bus would not af fect the ability I
to a c h ie v'e a cold shutdown condition.
B.
Modifications are in the design stages to make improvements in
~
the control room to provide redundant instrumentation for this parameter in the control room.
C.
This parameter can be determined from other parameters, if needed.
Loss of this parameter would not affect the ability to achieve a cold shutdown condition.
D.
A modification will be initiated to provide separate feeds for existing instrumentation.
Presently if torus level narrow range instruments are lost, torus level wide range instruments are still available, thus, the loss of one bus would not affect the ability to achieve a cold shutdown condition.
E.
This parameter is monitored by instruments which are fed from two separate circuits from two separate buses; thus, the loss of one bus would not a f fec t the ability to achieve a cold shutdown condition.
F.
Loss of this parameter would not affect the ability to achieve a cold shutdown condition.
G.
Local instruments are available to monitor this parameter, if needed.
H.
HPCI System Instrumentation i
The High Pressure Coolant Injection System instrumentation in the r
control room is fed from bus BD25, a 125V DC bus fed from Class 1-E Battery BD01.
If bus BD25 is lost, HPCI instrumentation in the control room and a flow controller are lost rendering the HPCI system inoperative.
The HPCI system ensures that tile reactor is adequately cooled in the event of a small break in the nuclear system and loss of coolant which does not result in rapid depressurization of the reactor vessel.
If the HPCI system is inoperative the ADS will i
be used to depressurize the reactor vessel so that the LPCI and l
Core Systems can be used.
Loss of the HPCI instrumentation and flow controller would not t
affect the ability to achieve a cold shutdown condition.
The flow controller is fed from a static inverter that is supplied l
from the BD25 distribution panel.
There is a power monitor on 6
.__7y-
e 4
the output o f the inverter.
If the output of the inverter is lost, or the supply to the inverter is lost causing the loss of the output, the HPCI Inverter Power Failure alarm annunciates in the control room.
J.
Reactor Core Isolation Cooling System The Reactor Core Isolation Cooling System instrumentation in the control room is fed from bus AD25, a 125V DC bus fed from Class 1-E Battery AD01.
If bus AD25 is lost, RCIC instrumentation in the control room and a flow controller are lost rendering the RCIC system inoperative.
The RCIC system ensures that the reactor is adequately cooled during shutdown and isolation.
The HPCI system will provide backup if the RCIC system is inoperative.
Loss of the RCIC instrumentation and flow controller would not af fect the ability to achieve a cold shutdown condition.
The flow controller is fed from a static inverter that is supplied from the AD25 distribution panel.
There is a power monitor on the output of the inverter.
If the output of the inverter is lost, the ~nverter Failure
- alarm annunciates in the control room.
(RCIC) is not inscribed on the annunciator window, however, the balance of the annunciator panel (25 windows) is l
dedicated predominately (all but 2 windows) to the RCIC system.
l K.
Core Spray Instrumentation The Core Spray system instrumentation in the control room is fed from the 120V AC Bus Y33.
The Core Spray System controls for Loop "A"
are fed from the 125V DC Battery AD01 and for Loop "B"
are fed from the 125V DC battery BD01.
Thus, if Y33 Panel is lost, the core spray instrumentation in the control room is lost, but the Core Spray System remains operative.
I The Core Spray System provides protection to the core for large breaks in the nuclear system and either loop provides sufficient protection.
The protection provided by the Core Spray System also extends to a small break in which the ADS has operated to lower the reactor vessel pressure so that the Core Spray System can provide core cooling.
If the Core Spray System is inoperative the LPCI System is the backup system that will provide core cooli e.
Loss of the Core Spray System inscrumenta
<n would not affect the ability to achieve a cold shutdown c o r.
ition. l l
L.
Recidual Heat Removel System The Residual Heat Removal System is composed of 2 redundant 5
loops, each consisting of 2 pumps and 2 heat exchangers.
The pressure indicators.and pressure controllers in the control room are fed from the 120V AC Bus Y33 for the A-C loop and from the 120V AC Bus Y34 for the B-D loop.
The flow controller on the "A"
pump discharge is fed from the 120V AC Bus Y33 and the flow controller on the "D" pump discharge is fed from 120V AC Bus Y34.
l The flow indicators in the control room are fed from Bus Y33.
The indicator for the various RHR temperatures is fed from the
[
120V AC uninterruptable power Bus Y50.
The loss of one bus feeding RHR instrumentation would not affect l
the operating capability of the RHR System and, thus, would not affect the ability to achieve a cold shutdown condition.
M.
Rod Position Information System The Rod Position Information System is fed from the 120V AC uninterruptable power Bus Y50.
This bus is fed from an inverter with automatic transfer provided to a 120V AC source fed from the "A"
diesel generator.
If power to Bus Y50 is lost, rod position information will be lost in the control room.
This will prohibit manual movement of control rods, but will not prohibit a manual or an automatic SCRAM.
Thus, the ability to achieve a cold shutdown condition would not be affected.
8 -
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