ML20054K034
| ML20054K034 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 03/22/1982 |
| From: | MISSISSIPPI POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20054J949 | List:
|
| References | |
| 05-1-02-V-15, 5-1-2-V-15, NUDOCS 8206300321 | |
| Download: ML20054K034 (4) | |
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t PLANT OPERATIONS MANUAL h.w?r, Volume 05 05-1-02-V-15 Revis ion:
10 Section 02 Date: 3-22-82 a
OFF-NORMAL EVENT PROCEDURE LOW SYSTEM FREQUENCY t
SAFETY RELATED
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Prepared: _ [h l\\,. em Reviewed:
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7 Nuclear Plant Quality Superintendent
/ Technica1' Review Reviewed:
- b. f u Oper t ions Superintendent Approved:
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Assistan tant Mana
.,I//6, 8L PSRC:
i List of Ef fective Pages:
Page:
Revision:
1-3 10
&y 8206300321 820625 PDR ADOCK 05000416 P
r GRAND GULF NUCLEAR STATION OFF-NORMAL EVENT PROCEDURE
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Title:
Low System Frequency lNo.:
05-1-02-V-15 l Revis ion:
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s' 1.0 PURPOSE / DISCUSSION 1.1 To establish guidelines for initiating a manual load rejection due to low
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or unstable system frequency.
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1.2 Should it become necessary to perform a manual load rejection due to Low System Frequency, or if the plant trips due to an unsuccessful load rejection, the Emergency Plan should be initiated in accordance with 10-S-01-1.
1.3 If the system frequency decreases or becomes unstable, as in the case of a large loss of generating capacity on the system, it may be necessary under certain circumstances for the operator to perform a manual load reduct ion in order to protect the Unit and maintain it readily available to be placed on-line when system conditions warrant. The Unit is designed to accept a loss of external electrical load up to 30% power without actuating a Reactor Scram. The automatic Turbine Bypass System can accommodate up to 35% power, bypassing the Turbine steam to the Main Condenser.
Power must be reduced to less than 30% with Reactor Recirculation Flow control and manual control rod insertion to prevent the scram.
The operator should make every ef fort to keep the Unit on-line.
h Separation of a unit from the system will cause the frequency to drop still lower, making it necessary for other units to be separated, and a complete system loss could result. The operator should make all preparations necessary to increase Unit load to the maximum allowable, but should always be within the core limitat ions. Aiding the system during low frequency conditions cannot take priority over safe operation of reactor Systems.
2.0 SYMPTOMS 2.1 Notification by Jackson System Dispatcher of system problems.
2.2 Generator Underfrequency alarm on panel 1H13-P680 (Alarm at 58.3 Hz.).
2.3 System f requency dropping or unstable as indicated on SR27-R600 on panel SH13-P807.
3.0 AUTOMATIC ACTIONS 3.1 None above 58 Hz - main generator trips on underfrequency at 57 Hz.
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GRAND GULF NUCLEAR STATION OFF-NORMAL EVENT PROCEDURE I
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Low System Frequency (No.:
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4.0 IMMEDIATE OPERATOR ACTION I
j 4.1 Check with Jackson System Dispatcher.
l 4.2 Increase Unit load as directed by the dispatcher, if possible.
t 4.3 Closely monitor system frequency:
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4.3.1 Unlimited operating time is permitted as long as frequency is greater than 59 Hz.
4.3.2 If less than 59 Hz but greater than 58 Hz, the maximum operating i
time is 30 minutes.
If frequency is not restored after 30 minut es, separate from the system in accordance with 4.4.1 and 4.4.2.
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4.4 If frequency drops to 58 Hz:
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4.4.1 If possible, immediately reduce reactor power to less than 30%
l before separating from the grid, to prevent a turbine Fast Control j
Valve (FCV) closure trip and subsequent Reactor Scram.
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4.4.2 Separate the generator from the system by opening 500 KV Breakers J5228 and J5236 (J5236 control is located in the 500 KV Switchyard Control House, or the dispatcher can open it).
i 4.5 After the Generator has been separated from the system:
j 4.5.1 Reduce power in order to maintain auxiliary loads while minimizing bypass valve operation and feedwater flow oscillations.
j 5.0 SUBSEQUENT ACTIONS 5.1 As necessary, transfer Reactor level control to manual to maintain stable cond it ions.
5.2 Maintain Generator frequency at 60 Hz and prepare to bring the Unit on-line, when so advised by Jackson System Dispatcher.
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.e GRAND GULF NUCLEAR STATION OFF-NORMAL EVENT PROCEDURE l Tit le : Low System Frequency lNo.:
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5.3 Refer to Tech. Spec. Section 3/4.8 Electrical Power Systems.
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5.4 If the load rejection was unsuccessful and a Reactor Scram occurred, j
carry out the actions of Reactor Scram ONEP 05-1-02-I-1, 1
_. 5. 5 If, following a Reactor Scram, the system frequency remains lesc than 59 Hz, it may be necessary to use the Standby Diesel Generators to supply the ESF Buses. Refer to ONEP 05-1-02-I-4, Loss of Of fsite Power.
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