ML19210A158

Abnormal Occurrence 50-289/75-43:on 751218,one of Six Pressure Switches Tripped at Less Conservative Limits than Tech Specs During Channels Surveillance Test.Caused by Calibr Drift in Associated Pressure Switch PS-290

ML19210A158
Person / Time
Site:	Three Mile Island
Issue date:	12/26/1975
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-0159, GQL-159, NUDOCS 7910240883
Download: ML19210A158 (4)

Text

• NRC T"'9UTION FOR PART 50 DOCK M ATERI AL

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FILE: It:01DE :: nErenT r DATE OF DOC DATE REC D LTR TWX RPT OTHER FROM: Met. Edison co.

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1 50-289 DESCRIPTION: Ler reporting A0-50-289/75-43 dn ENCLOSURES:

12-13-75 .re out of spec serp.oing"for a reactor building 30 psig c.hannel pressu: e switch.... .. g g]ppgtg j

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PLANT N AME: Three Mile Ilsand Unit 1 ,

FOR ACTION /INFORMATION Dnt 1-5-76 BUTLER (L) SCHWENCER (L) ZIEM ANN (L) REG AN (E)

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W/ Coods W/ Cocies W/ Cocies W/ Copies PARR (L) VASSALLO (L) KNIGHTON (E) SPELS W/ Copies .W/ Copies W/ Copics W/ Copics KNIEL (L) PUPPLE (L) YOUNGBLOOD (E) 842ID W/ Copics V// Copies W/ Cooics W$opies

. INTERNAL DISTRIBUTION TECH REVIEW DENTON LIC ASST A/T IN D KREG H En R. DIGGS (L) SRAITHAN

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GOSSICK/ STAFF KNIGHT KASTNER E. GOULBOURNE (L) MELTZ f CASE PAWLICKl BALLARD P. KREUTZER (E)

SHAO SPANGLER J. LEE (L) PLANS _

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P. COLLINS .fTEDESCO YOUNGBLOOD H. SMITH (L) HARTFIELD (2)

DENISE J. COLLINS REGAN S. TEETS (L) KLECKER REG OPR LAIN AS PROJECT LDR G. WILLI AMS (E) EISENHUT

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Dear Sir:

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Decket :To. 50-EM '

Opers. ting License No. DPR-50 In acecrdance with the Technical Specificatiens of our Three Mile Island Nuclear Station Unit 1 (TMI-1), we are reporting the following abner =al occurrence.

(1) Report Nu=ber: A0 50-289/75 h3 (2a) Report Date: December 26, 1975 (2b) Occurrence Date: December 18, 1975 (3) Facility: Three Mile Island Nuclear Station Unit 1 (h) Identification of Occurrence:

Title: Out-of-Specificatien Setpoint for a Reactor Building 30 psig Channel Pressure Switch Tvpe: An abnormal occurrence as defined by the Technical Specifications, paragraph 1.8a, in that the trip setpcint for one of the six (6) pressure switches for the Reacter Building 30 psig channels was fcund to be less conservative than the setpoint listed in Technical Specification 3.5.3.1. ,

(5) Conditions Prior to Occurrence:

The reactor was at cold shutdem conditien with major plant parameters as follevs:

Power: Cere: 0 ",

Elec.: 0 M'ie RC Flev: 0 lbs/hr. 14]Cil-RC Pressure: O psig 1490 092

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RC Temp.: 150 F PRZR Level: L2 inches PR2R Te=p.: 1500F (6) Description of Occurrence:

Cn Dece=ber 18, 1975, while conducting the Refueling Interval Reactor Building 30 psig Channels Surveillance Tes;, cne or the six (6) pressure switches was found to trip at a pressure less conservative than the trip setpcint listed in Technical Specificatien 3.5 31. The required and actual trip setpoints for the pressure switch out-of-specification, PS-290, were < 30 pais and 30 5 psig respectively.

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The cut-of-specification pressure switch was recalibrated and retested and the resulting trip setpoint was verified as being within Technical Specification limits. The remaining five (5) similar pressure switches were determined to be within the Technical Specification limits.

(7) Designation of Apparent Cause of Occurrence:

The cause of this occurrence has been determined to te material in that the out-of-specification trip setpoint was due to ciner calibraticn drift experienced in the associated pressure switch, PS-290. This pressure switch was last calibrated en January 15, 1974.

(8) Analysis of the Occurrence:

It has been determined that this occurrence did not constitute a threat to the health and safety of the public in that the setpoints for the other five (5) Reactor Building 30 psig channels pressure switches were within the Technical Specifications 11=its end .tuld have performed their protective function had an overpressure condition occurred.

(9) Corrective Action:

In addition to the i= mediate action described above, the Plant Operaticns

- Review Cc=rittee evaluated the present ncminal setpv.at and determined that it is sufficiently conservative. Since subsequent refueling intervals vill be shorter than the present initial cycle, these pressure switches vill be calibrated more frequently, with resultant less chance of setpcint drift beyond the Technical Spec!fications limits.

(10) Failure Data:

Square D Co. Pressure Switch Type 9013 - AMG5 Form "R" 0-100 psig Range

+ 25 Accuracy 1490 093

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Similar Occurrences: Ncne Sincerely, si ,

R. C. Arncid Vice President RCA:JFE:tas ec: Office of Inspection and Enforcement, Region 1 1490 094