IR 05000373/1986013

Insp Repts 50-373/86-13 & 50-374-86-13 on 860327-0403.No Violation or Deviation Noted.Major Areas Inspected.Part 21 Notification on Sor,Inc Pressure Switches

ML20203D330
Person / Time
Site:	LaSalle
Issue date:	04/17/1986
From:	Muffett J, Westberg R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20203D309	List: IR 05000373/1986013 ML20203D305
References
50-373-86-13, 50-374-86-13, NUDOCS 8604220083
Download: ML20203D330 (5)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION III

Reports No. 50-373/86013(DRS); 50-374/86013(DRS)

Docket Nos. 50-373; 50-374 Licenses No. NPF '.1; CPPR-100 Licensee: Commonwealth Edison Company P.O. Box 767 Chicago, IL 60690 Facility Name: LaSalle County Station, Units 1 and 2 Inspection At: LaSalle Site, Marseilles, IL Inspection Conducted: March 27 and April 3, 1986 Inspector: R. A. Westberg W[19 [ &f:,

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Approved By: J. W. Muffett, Chief 4 !I7 !db Plant Systems Section ..Date Inspection Summary Inspection on March 27 and April 3,1986 (Reports No. 50-373/86013(DRS);

No. 50-374/86013(DRS)) .

Areas Inspected: Routine, announced inspection by one regional inspector of Part 21 notification on SOR pressure switches. It was conducted in accordance with NRC Inspection Procedures 92700 and 9071 Results: No violations or deviations were identifie s604220083 e60417 PDR ADOCK 050003 3

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DETAILS 1. Persons Contacted Commonwealth Edison Company (CECO)

• J. Diederich, Station Manager R. D. Bishop, Services Superintendent

• D. S. Berkman, Assistant Services Superintendent

• P. F. Manning, Technical Staff Supervisor

• M. Cray, Instrument Maintenance Supervisor D. A. Spencer, Technical Staff Electrical Group Leader R. J. Cozzi, Quality Assurance Engineer

• M. G. Santic, Master Instrument Mechanic

• T. Hammond, Technical Staff Complianc US NRC M. J. Jordan, Senior Resident Inspector

• R. A. Kopriva, Resident Inspector

• J. C. Bjorgen, Resident Inspector Other personnel were contacted as a matter of routine during the inspectio * Indicates those attending the exit meeting on April 3, 1986.

2. Review of SOR pressure Switch Anomalies The SCRAM review following the February 16, 1986 reactor scram identified a problem with the Channel A low Low Set (LLS) logic. Immediately after the SCRAM, six steam relief valves (SRVs) opened but the LLS did not lock in the proper positio Surveillance Test No.86-023, " Low Low Setpoint Functional Test", was performed on the channel and it indicated that the logic was not at faul This in turn indicated a problem with the SRV pressure switches, since the opening of any two of the SRVs should have locked in the LLS logic channe The SRV pressure switches are an environmentally qualified Class 1E static o-ring pressure switch supplied by SOR, Incorporated. They are a single pole double throw (SPDT) switch in a cast iron case with 3 steel cover and sealed electrical leads. The pressure sensing element of the switch is a Type 316 stainless steel force balance piston-actuated assembly sealed by flexible diaphragms and an o-ring that is static. Only the pressure port, the diaphragms, and the o-ring come in contact with the process flui The o-ring is made of ethylene propylene rubber (EPR), the primary diaphragm is made of kapton polyimide, and the backup diaphragm is made of fluorinated silicon. The range of the switch is 100 to 1750 pounds per square inch (psi).

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On February 17, 1986, the licensee calibrated two of the switches (NO39) which energize the aute logic on the SRVs. This calibration produced an anomaly; the switches initially tripped at a value much higher than expected. However, after cycling the switch the setpoint returned to the expected range. The licensee concluded that to explain the LLS logic failure, five of the six SRV pressure switches failed to activate during the scra On February 18-19, 1986, the remainder of the N039 switches were calibrated with the majority showing the same anomaly. The average initial setpoint drifting up by 39 psi with one (NO39 A/S) drifting up by 58 psi. Then the licensee expanded the calibration checks to selected technical specification (TS) SOR switche On February 20, 1986, the licensee expanded the calibration effort to either functionally check on calibrate all SOR high pressure switche The manufacturer, SOR, was contacted and a meeting was scheduled at the LaSalle site. The NRC resident inspector was also informed of the proble On February 21-24, 1986, calibration of SOR switches continued with the setpoint anomaly evident on the high pressure switches only. The licensee now committed to reduce the functional test interval on all high pressure SOR switches to bimonthly. The meeting was held with SO On February 26, 1986, the licensee received a letter from SOR outlining their research program to determine the cause of the setpoint drift anomaly. This program would try to duplicate the unusual behavior by manufacturing 12 switches to the LaSalle specification (S&L No. T-3702)

.and testing them in-house at ambient temperature with 1000 psi static pressure applied. Then they will investigate possible causes and solutions that could explain the anomalous behavior. The test program was expected to last nine week On February 28, 1986, the Senior Resident requested assistance from Region III in reviewing the SOR pressure switch problem. He had three concerns. The concerns were the generic implications of the problem, the practice of cycling the pressure switches prior to calibration, and the reportability potential of the problem. The purpose of this report is to review the licensee's actions relative to these concern Documents Reviewed (1) Sargent and Lundy Specification No. T-3702, " Pressure Switches LSCS Units 1 and 2, CECO."

(2) Procedure No. LIS-NB-205, " Unit 2 Reactor High Pressure SCRAM and Alarm Calibration," Rivision (3) Procedure No. LIS-NB-214, " Unit 2 Reactor High Pressure Automatic Blowdown Calibration," Revision (4) Licensee Event Report No. 50-374/86-007-00, " Excessive Static-0-Ring Pressure Switch Drif t", Revision 0

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b. Results of Inspection On March 27, 1986, the inspector reviewed the S&L specification for the SOR pressure switches and selected surveillance test and calibration procedures. The inspector also interviewed selected personnel relative to the problem and reviewed the sequence of events-to date. The current opinion from SOR was that the setpoint drift was due to process fluid getting between the primary and secondary diaphragm. Then when the switch is cycled during functional testing or calibration, the process fluid is squeezed out and the setpoint returns to the normal rang On April 3, 1986, the inspector returned to the site and discussed the 10 CFR Part 21 reportability aspects of the problem and the and the progress of licensee activities to date. At th',s time, the licensee presented the latest opinion from SOR. SOR currently believes that the cause of the drift due to the LaSalle specifica-tion requirement to hydrostatically (hydro) test the pressure-valves at one and a half times the system pressure or 2000 ps SOR normally hydro tests at 2500 to 3000 psi which is sufficient to plastically deform the diaphragm, that is, take it out of its elastic range and conform it to the shape of the piston. Since the LaSalle pressure switches were not hydro tested to the higher pressure and do not see it in operation, the diaphragm is still elastic. Therefore, it grows when it is exercised which gives it a lower setpoint. Then when the switch sits inactive, the diaphragm shrinks back to its original shape and the setpoint raises. This theory will be tested by SOR with the results due in nine week Pending further review by the inspector during a future inspection, this item is unresolved (373/86013-01A; 374/86013-01A).

The inspector's review indicated that while the SOR pressure switch drift problem is generic for the LaSalle switches, it does not appear to be generic to the industry. This is because the LaSalle specification requirement for hydro pressure was different from SOR's normal hydro pressure (2000 vs 2500 psi) and appears to have caused the problem. Both the licensee and SOR have acted responsibly relative to this problem. The licensee has kept the NRC informed and SOR contacted all nuclear plants using their switches. Further, the licensee made an official notification under 10 CFR Part 21 on April 4,1986 (LER No. 50-374/86-007-00).

The inspector's review of the practice of cycling the pressure switch prior to calibration indicated that half of the utilities contacted endorse this practic The licensee is currently evaluating the practice since the cycling of the pressure switches may have masked this problem. Pending further review by the inspector during a future inspection, this is considered open (373/86013-02; 374/86013-02).

On March 4, 1986, the inspector reviewed LER No. 50-374/86-007-00 at Region III. Pending the review of the final supplement to this LER, this item is unresolved (373/86013-01B; 374/86013-01B).

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3. Exit Interview The. inspector _ met with licensee representatives on April 3, 1986, and summarized the purpose,-scope and findings of the inspection. The inspector also discussed the likely informational content of the-inspection report with regard to documents or processes reviewed by the inspector during the inspectio ..