ML18052A398
| ML18052A398 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 04/23/1986 |
| From: | Kuemin J CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8604290219 | |
| Download: ML18052A398 (7) | |
Text
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consumers Power POW ERi Nii MICHlliAN'S PROliRESS General Offices: 1945 Wast Parnell Road, Jackson, Ml 49201 * (517) 788-0550 April 23, 1986
- Director, Nuclear Reactor Regulation US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT -
PRELIMINARY SYSTEM DESCRIPTION FOR PROPOSED DIVERSE ATWS TRIP Consumers Power Company's letter of October 22, 1985 committed to provide, as required by 10CFR50.62(c)(6), information to demonstrate the adequacy of our proposed modifications to the requirements of 10CFR50.62(c)(l) and (2).
Attached hereto is that information.
Members of Consumers Power Company's and NRC's staff met on March 19, 1986 to discuss our proposed modifications and present plant configuration with respect to reactor trip, turbine trip and auxiliary feedwater initiation.
Since that meeting there have been some changes to our conceptual design for turbine trip and auxiliary feedwater initiation.
An independent turbine trip will be provided by energizing the diverse electro-hydraulic fluid dump valve relay 20/ET from an independent power supply.
An. independent method to provide auxiliary feedwater initiation will be to install a solenoid valve to automatically start the steam driven auxiliary feed pump on loss of DC power.
Ndrmal AFAS will be initiated by DC power while loss of DC power will then initiate the steam driven AFW pump.
Loss of electrical power or loss of air supply will also provide an unobstructed flow path to the steam generators from the steam driven pump through control valves CV-0727 and CV-0749.
The control valves fail open on either loss of power or loss of air.
The remaining valves in the flow path, from the suction supply to the steam generators, are normally open and remain open in a loss of power condition.
OC0486-0074-NL04
Director, Nuclear Reactor Regulation Palisades Plant Preliminary System Description April 23, 1986 A conceptual schedule showing major milestones for these proposed modifications will be completed by the end of June and then be transmitted to your office.
The implementation of the modifications will coincide with the end of the 1987 refueling outage.
~~~ *c~
~*~**
Kuemin Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident. Inspector - Palisades Attachment OC0486-0074-NL04 2
I'.*.
IC0486-0074-NL04 ATTACHMENT.
Consumers Power Company Palisades Plant Docket 50-255 PRELIMINARY SYSTEM DESCRIPTION FOR PROPOSED DIVERSE ATWS TRIP April 23, 1986 4 Pages
PRELIMINARY SYSTEM DESCRIPTION FOR PROPOSED DIVERSE ATWS TRIP 1
Pressurizer pressure is sensed utilizing existing pressure transmitters PT0l02A thru D.
The output of these transmitters is fed to the Reactor Protection System (RPS) and Safety Injection System (SIS) circuitry.
The RPS is located in control room panel C-06 and the SIS is located in control room panel C-12 and is actuated by pressure indicating alarm indicators PIA0102 ALL thru DLL.
These dual setpoint indicators will be replaced by indicators with three setpoints.
Two of those setpoints will continue to be used for safety injection initiation and safety injection block.
The third setpoint, which will be set at the same level as the high pressurizer pressure RPS trip setpoint, will activate relays in an ATWS dedicated two out of four logic matrix.
The output of this logic matrix will energize a relay which will open contacts to interrupt pref erred AC power to the clutch power supplies and also close a contact to provide a turbine trip.
In order to meet the power supply independence for the high pressurizer pressure ATWS trip, power will be supplied from panel Y230A which is ultimately fed from non-IE battery D204.
D204 is the power supply for the feedwater purity datalogger and critical functions monitor.
The turbine trip relay will be energized from distribution panel D205 which is also fed from battery D204.
The existing AFAS is presently designed to class lE requirements complete with separation and redundancy and is powered from the two station batteries D-01 and D-02.
These batteries also power the existing RPS circuit.
As an alternative method to provide power supply independence between the RPS and AFAS Consumers Power Company intends.to redesign the steam driven auxiliary feedwater pump start circuit such that loss of power will start the pump and align the valving to deliver water to both Steam Generators.
Diverse RPS, Theory of Operation The clutch power supplies will be deenergized and the turbine will be tripped for the diverse ATWS trip by*the following sequence of events:
(See figures 1 and 2).
Pressure transmitter PT0102x senses increasing pressurizer pressure.
Pressure indicating alarm PIA0102xLL follows the transmitter signal and updn reaching high pressurizer pressure setpoint, closes the third (ATWS) setpoint contact.
This completes the circuit from Y230A to matrix relay (xx) which.energizes and closes contacts in the two out of four matrix.
When two or more matrix relays are energized, a circuit is completed from Y230A to the diverse clutch power supply trip relay which energizes and simultaneously actuates three sets of contacts.
The first contact opens and interrupts the circuit between Y30 and CBl causing a loss of power to DC power supplies PSl and PS3 thus causing loss of the redundant clutch OC0486-0074-NL04
2 power supplies.
The second contact opens and interrupts the Y40 to CB2 circuit causing a loss of power to DC power supplies PS2 and PS4 which deenergizes all control rod drive clutches and rods drop into the core.
The third contact closes to apply power from D205 to solenoid 20/ET which causes a turbine trip.
OC0486-0074-NL04
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