ML18082B171

Natural Circulation Tests.

ML18082B171
Person / Time
Site:	Salem
Issue date:	09/08/1980
From:	COMMONWEALTH EDISON CO.
To:
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ML18082B170	List: ML18082B169 ML18082B171
References
NUDOCS 8009160355
Download: ML18082B171 (5)

Text

( ( ,_ PUBLIC SERVICE ELECTRIC AND GAS SALEM NUCLEAR GENERATING STATION UNIT II NATURAL CIRCULATION TESTS

' '.. .. ... *.

• The Natural Circulation Test Program was successfully performed at Salem Unit II conn:nencing on August 23, 1980 and ending August 29, 1980 as outlined in Table 1. The test program consisted of the following tests: 1) SUP 90.1 Natural Circulation Test 2) SUP 90.2 Natural Circulation with Simulated Loss of Off site AC Power. 3) SUP 90.3 Natural Circulation with Loss of Pressurizer Heaters. 4) SUP 90.4 Effect*of Steam Generator Secondary Side Isolation on Natural Circulation.

5) SUP 90.5 Natural Circulation at Reduced Pressure.

6) SUP 90.6 Cooldown Capability of Charging and Letdown. 7) SUP 90.7 Simulated Loss of All Onsite and Offsite AC Power. The tests performed successfully demonstrated natural circulation upon the tripping of all RCP's with the reactor critical at approximately 3% RTP and with various portions of the plant equipment inoperable while in the natural circulation mode. The first test performed, SUP 90.6, Cooldown Capability of Charging and Letdown, demonstrated the ability of the CVCS to remove heat from the Reactor Coolant System with one RCP running*and all steam generators isolated.

With maximum 8harging and letdown the rate of temperature change is 7.3 F per hour and 4.5°F per hour with minimum charging and letdown. Following the completion of SUP 90.6, preparations were made for the performance of SUP 90.1, Natural Circulation.

Those preparations consisted of defeating various reactor trips and safety injection functions, reducing NIS setpoints are performing NIS functionals.

The reactor was taken critical and power raised to approximately 3% RTP as determined using a primary heat balance. The incore detector system was calibrated at 3% RTP for later use in determining core power while in the natural circulation mode, SUP 90.1, Natural Circulation, was performed to demonstrate the capability to remove decay heat by use of natural circulation.

The reactor was at approximately 3% RTP when all four RCP's were secured.

• Core power was monitored using the incore detectors and core exit temperature using thermocouple maps. Natural circulation was verified by use of the wide range RTD's. Temperature responded as expected and-no anomolies were noted. The 40°F and the hottest incore thermocouple SUP 90.3, Natural Circulation with Loss of Pressurizer Heaters, followed SUP 90.l to demonstrate the ability to maintain natural circulation and saturation margin with the loss of pressurizer heaters. While in the natural

• circulation mode.the pressurizer heaters were turned off and the RCS allowed to depressurize.

The depressurization rate was determined to be 105 psi per hour. Charging and steam were varied to allow operator training on controlling the saturation margin. After demonstrating the ability of the operators to control the saturation margin the pressurizer heaters were restored to service and the RCS pressure restored to normal. SUP 90.5 Natural Circulation at Reduced Pressure, followed the second run of 90.1. The test method of depressurization was the same as SUP 90.3 with the exception that auxilary spray was used to accelerate the depressurization rate. The saturation margin was calculated and compared to the saturation meter indication and verified the meter accuracy.

Upon successfully demonstrating the capability to control the saturation margin the pressurizer heaters were restored to service and the RCS pressure restored to normal. SUP 90.4, Effect of Steam Generator Secondary Side Isolation on Natural Circulation, was next performed to determine the effects of steam generator secondary side isolation on circulation.

was at 1% power and Tavg 510 F in the natural circulation mode. The feedwater and steam lines for one steam generator were isolated and the RCS allowed to stabilize.

After stabilization the feedwater and steam lines for a second steam generator were isolated and the RCS allowed to stabilize.

The transients were very slow and were easily followed by the operators.

Plant meters responded as expected with the maximum Delta T observed being 55°F and no indication of reverse flow in the isolated loops. The isolated steam generators were restored to service and natural circulation was verified to exist in all four loops. The reactor was shutdown and preparations made for SUP 90.2 SUP 90.2, Natural Circulation with Simulated Loss of Offsite AC Power, was next performed to demonstrate that following a loss of off site AC power natural circulation can be established and maintained while being powered from the emergency diesel generators.

The reactor was at 1%* power and all RCP's running when all RCP's were tripped and the vital bus infeed breakers tripped open:

-. The diesel generators successfully started and picked up the vital loads and natural circulation was maintained in all RCS loops. Normal AC power was restored to the vital buses and the reactor shutdown in preparation for re-runs of SUP 90.1 (1), 90.2 (1), 90.3 (1) and 90.5 (2) for additional operator training.

SUP 90.7, Simulated Loss of all Onsite and Offsite AC Power was performed last to demonstrate that following a loss of onsite and offsite AC power, including the emergency diesel generators, that the decay heat can be removed by using the steam driven auxilary feedwater pump in the manual mode. The reactor was shutdown and all four RCP's operating when the simulated station blackout was initiated.

The batteries provided and lightly power and the steam driven auxilary feedwater pump was proven*capable of maintaining the plant in hot standby conditions.

Upon completion of SUP 90.7 the entire Natural Circulation Test Program had been successfully completed.

The plant was brought to Mode 5 for repair of a control rod drive mechanism vent which was leaking. Following the return to low power operation several of the natural circulation tests will be re-run to complete the operator training program prior to power escalation. TABLE 1 TESTING SEQUENCE Date Event Saturday, August 23 Review License Amendment Performed SUP 90.6 Saturday, August 23 Modifications made to Reactor Protection Systems and Reactor through brought critical.

Performed SUP 90.1 Monday, August 25 Performed SUP 90.3 Tuesday, August 26 Performed SUP 90.1 Performed SUP 90.5 Performed SUP 90.4 Wednesday, August 27 Performed SUP 90.2 Performed SUP 90.1 Thursday, August 28 Performed SUP 90.3 Performed SUP 90.5 Friday, August 29 Performed SUP 90.2 Performed SUP 90.5 Performed SUP 90.7