ML20066E378
| ML20066E378 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/08/1982 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8211150140 | |
| Download: ML20066E378 (4) | |
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PHILADELPHIA ELECTRIC COMPANY 23ol M ARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 SHIELDS L DALTROFF ELECTR C PR D C ION November 8, 1982 Docket Nos. 50-277 50-278 Mr. John F. Stolz, Chief Operating Reactors Branch #4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
SUBJECT:
Peach Bottom Underfrequency Protection of the Reactor Protection System (RPS) M-G Sets
Dear Mr. Stolz:
In a letter to you, dated May 21, 1982, we committed to conduct tests at Peach Bottom to determine the minimum frequency i
level that the output of the M-G set, with loss of power, would i
reach after six seconds, and also to determine any effects I
experienced on selected RPS components when operated at this minimum frequency.
These tests have been completed and the results have been analyzed.
Tests were conducted at Peach Bottom to determine the minimum frequency that the RPS M-G set output would reach following loss of power and a six second time delay.
The test was performed by interrupting power to the emergency 4KV bus, allowing the M-G sch to coast down.
It was found that the lowest frequency reached was 54.4 Hz during a 7 1/2 to 11 second time period, depending upon load on the 4kV bus.
1 Bench tests were conducted on an HFA relay, a scram
,00 contactor, and a scram solenoid valve.
The tests simulated the M-G set output by maintaining voltage and reducing frequency gradually to 53 Hz during 11 second and 15 second intervals.
As l
the frequency was lowered, the accompanying increases in coil l
current were measured and changes in coil temperature were 140 821108 f$k kDOCK 050002((
P
r Mr. John F. Stolz, Chief Page 2 monitored with a thermocouple.
The components were tested twenty times with this procedure.
It was found that the temperature of the HFA relay and scram contactor coils increased an average of 0.1 degrees F, or less than 0.1%, for each test.
The temperature of the scram solenoid valve coil increased an average of 0.8 degrees F, or less than 0.5%, for each test.
The coil currents increased when the frequency was lowered.
The components were examined when the voltage was removed and reapplied during and after the tests.
The components functioned correctly for each event.
The test conditions that were used were more severe than those expected in the plant.
Since the tested components operated correctly under repeated bench tests, it can be concluded that they will operate correctly with a six second time delay setting for initiation of underfrequency tripping.
In addition, the heat rise of the coils during underfrequency conditions was so small that it will not affect performance of the components during a single event or promote degradation of the coils after repeated events.
The tests have demonstrated that the six second time delay before initiation of underfrequency tripping will not adversely affect the performance of these RPS components.
An attachment to this letter describes in more detail the testing procedure used, the compocents tested, and the data obtained.
If you have any questions or require additional information, please do not hesitate to call.
Very truly yours, f,
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ATTACHMENT I
RPS Underfrequency Tests This summarizes tests for RPS M-G set response after loss of power.
RPS M-G set was deenergized by tripping supply to 4KV bus.
Test #1 - Only Load Center load on 4KV bus Test #2 - Load Center & Motor load on 4KV bus Test il Test #2 Voltage Freq.
Time Voltage Freq.
Time 115 59.8Hz.
O Sec. 115 59.8Hz.
O Sec. 115 59 1.0 115 59 0.2 115 58 3.3 115 58 0.4 115 57 5.5 115 57 1.7 l
115 56 7.8 115 56 3.9 115 55 10.0 115 55 6.2 115 54.4 11.5 115 54.6 7.7 The following components were bench tested to determine response to a drop in frequency.
HFA Relay - Model 12HFA51A49F l
Scram Contactor - Model CR105D1 Series A Scram Solenoid Valve - Model HVA 904052A i
The following procedure was used:
1.
Connect components to 120 vac, 60 Hz test source and monitor voltage, frequency, current, and coil temperatures of each component.
Allow coil temperatures to stabilize under these conditions.
2.
Maintain voltage at 120 Vac and gradually reduce frequency to 53.0 Hz during 11 seconds.
Record any change in current and temperature for this time interval, and restore frequency to 60 Hz.
Verify that components drop-out when de-energized.
l 3.
If changes in current were noted, allow coils to l
stabilize for several minutes.
Repeat test 10 times.
4.
Repeat Tests 2 & 3 for a 15 second interval and 53.0 Hz.
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The following testing arrangement was used:
West PA151 Fluke 8022A Multi-Darey UTS41 meter &
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Test V
West Variable Temp. probe Coil PA151 frequency test set l
l The following results were obtained:
HFA Relay Current at 60 Hz - 0.28A.
Current at 53 Hz - 0.35A.
Ave. Temp. of Coil - 153.8 degrees F Test 1 - 10 Ave. Change in Temp. - 0.09 degrees F Test 1 - 10 Ave. Temp. of Coil - 173.2 degrees F Tests 11 - 20 Ave. Change in Temp. - 0.11 degrees F Tests 11 - 20 Scram Contactor l
l Current at 60 Hz - 0.46A.
Current at 53 Hz - 0.57A.
Ave. Temp. of Coil - 158.8 degrees F Tests 1 - 10 Ave. Change in Temp. - 0.1 degrees F Tests 1 - 10 Ave. Temp. of Coil - 159.0 degrees F Tests 11 - 20 Ave. Change in Temp. - 0.16 degrees F Tests 11 - 20 Solenoid Valve Current at 60 Hz - 0.25A.
Current at 53 Hz - 0.33A.
l Ave. Temp. of Coil - 182.7 degrees F Tests 1 - 10 Ave. Change in Temp. - 0.86 degrees F Tests 1 - 10 l
Ave. Temp. of Coil - 181.8 degrees F Tests 11 - 20 Ave. Change in Temp. - 0.84 degrees F Tests 11 - 20
-..