ML20197B032

Forwards Summary of Results from 860924 Operating Pressure Reactor Vessel Level Drop Test LST-86-208.Setpoint Stability for Level 3 Scram & Automatic Depressurization Sys Permissive Functions Consistent W/Characterization Program

ML20197B032
Person / Time
Site:	LaSalle
Issue date:	10/08/1986
From:	Allen C COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
2225K, NUDOCS 8610270449
Download: ML20197B032 (4)

Text

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- Commonwrith Edison 72 West Adams Street, Chicago, Illinois

• M J Address Reply to: Post Office Box 767 3 .

Nd Chicago, Illinois 60690 - 0767 October 8, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, Dg 20555

Subject:

LaSalle County Station Unit 1 SOR Differential Pressure Switch Setpoint Characterization Program 950 psig Reactor Vessel Level Drop Test NRC Docket No. 50-373 References (a): J. S. Abel letter to D. L. Farrar dated September 16, 1986 with Results of 0.0 psig Level Drop Test for Operability verification.

(b): Telecon, September 19, 1986, among members of NRR, Region III, Ceco Licensing, and j LaSalle Station Staff.

1

Dear Mr. Denton:

Reference (a) provides results of the 0.0 psig Reactor Vessel Level l Drop operability tests for the Level III Scram and ADS Permissive functions performed by SOR differential pressure switches on Unit 1 of LaSalle County Station. This letter serves to document results of a Level Drop Test conducted September 24, 1986 on the Unit 1 vessel while it was at normal operating pressure. The test, which had previously been scheduled for the first planned outage following three months of operation after startup of j the second refueling cycle (plant conditions permitting), was instead conducted September 24, 1986 per the telecon discussion referenced in (b) above.

l Special Test Procedure LST-86-208 was performed with the reactor at a pressure of 942 psig. Water level was lowered by blowing down reactor inventory through the Reactor Water Cleanup System to the condenser. Water level was monitored by recording the outputs of differential pressure transmitters located on the same instrument racks and sharing the same sensing lines as the SOR differential pressure switches performing the SCRAM and ADS permissive functions. Also, during the test, reactor pressure was monitored as well as the contact status of the relays which are de-activated by the SOR differential pressure switches to perform the scram and ADS logic confirmation functions.

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8610270449 861008 PDR ADOCK 05000373 p PDR l

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Mr. H. R. Denton October 8, 1986 The acceptance criteria for switch trip points had been pre-defined.

It was expected that alt six switches should trip between a low of +12.2" RWL and a high of +18.1" RWL. In addition, by using switch-specific static shift data from the SOR Setpoint characterization program, the latest known switch actuation points from the previous 0.0 psig level drop-test, and the known switch drift characteristics as observed in the SOR, Inc. long term time test data, the anticipated switch trip points were predicted.

The results of the test are shown in table 1. Four of the six switches tripped within 1" (Reactor Water Level) of their predicted values.

The two switches that did not trip within 1" of the predicted values were within the acceptance limits, but they tripped conservatively higher than predicted. The range of trip values, however, was comparabic to the range of trip values experienced in the LaSalle Unit 2 950 psig Level Drop Test conducted on August 10, 1986.

In general, the setpoint stability for level 3 SCRAM and ADS permissive functions was demonstrated by this test to be consistent with the LaSalle SOR Setpoint Characterization program, and was demonstrated to be adequate for performance of the safety actions required by the LaSalle Technical Specifications.

please direct any questions you may have regarding this matter to this office.

One signed original and ten (10) copies of this letter and its attachments are provided for your use.

Very truly yours, C. M. Allen Nuclear Licensing Administrator 1m Attachments cc: Dr. A. Bournia - NRR Resident Inspector - LSCS 2225K

E TABLE 1 Summary of Results from Operating Pressure Reactor Vessel Level Drop Test LST-86-208, conducted 9/24/86 Switch Tag # Predicted

• Trip 950 psig Actuation at Level Drop Test 1000 psig Switch Actuation 1B21-N024A 15.8" RWL 15.2" RWL 1B21-N024B 15.6" RWL 14.8" RWL 1B21-N024C 16.8" RWL 17.1" RWL 1B21-N024D 15.0" RWL 17.6" RWL 1B21-NO38A 16.1" RWL 17.9" RWL 1B21-NO38B 14.9" RWL 15.0" RWL

• The predicted values were calculated by adding the switch-specific static shift values from the LaSalle SOR Setpoint Characterization i program, and the drif t rate found in the SOR, Inc. Long Term Time Test, to the actuation points on the latest 0.0 psig Reactor Vessel Level Drop Test conducted on September 20, 1986. (See Table 2) l l

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v'e TABLE 2 Summary of Results of 0.0 psig Reactor Vessel Level Drop Test LST-86-207, conducted September 20, 1986 Switch Tag # Punction Measured Trip Measured Trip Instrument Point 9/9/86 Point 9/20/86 Drift

("RWL) ("RWL) ("W.C.)

IB21-N024A SCRAM Channel Al 19.8 18.4 + 0.98 i

1B21-N024B SCRAM Channel B1 18.9 17.9 + 0.70 IB21-N024C SCRAM Channel A2 19.3 18.4 + 0.63 1B21-N024D SCRAM Channel B2 19.6 18.1 + 1.06 IB21-N038A ADS Permissive 19.7 19.2 + 0.35 IB21-N038B ADS Permissive 18.7 18.4 + 0.21 2225K

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