ML20148T520

Forwards Final Response to Ib Bulletin 85-003, Motor- Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings

ML20148T520
Person / Time
Site:	Calvert Cliffs
Issue date:	01/28/1988
From:	Tiernan J BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
IEB-85-003, IEB-85-3, NUDOCS 8802030321
Download: ML20148T520 (7)

Text

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S ALTIMORE OAS AND ELECTRIC CHARLES CENTER R O. BOX 1475 BALTIMORE. MARYLAND 21203 JostPH A.TitmNAN WCt Pat $ tete,f NvC4 TAR (1,t hSt January 28, 1988 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 IE Bulletin 85-03, 'Atotor-Operated Valve Common hiode railures During Plant Transients Doe to Imoroner Switch Settines

REFERENCES:

(a) Letter from htr. J. A. Tiernan (BG&E) to Dr. T. E. Aturley (NRC),

dated hlay 15, 1986, same subject (b) Letter from htr. J. A. Tiernan (BG&E) to NRC Document Control Desk, dated September 1, 1987 Response to Request for Additional Information on IE Bulletin 85-03 Gentlemen:

This refers to IE Bulletin 85-03, item f, which requested a written report on completion of the subject program. Enclosure (1) prosides: (1) a s erification of completion of the sequested program; (2) a summary of the findings as to valse operability prior to any adjustments as a result of the subject bulletin; and (3) a summary of data in accordance with the suggested format. In conjunction with Reference (a), this letter prosides the information required by IE Bulletin 85 03.

Should you hase any further questions regarding this reply, we will be pleased to discuss them with you.

Very truly yours, 7.

{& ~

JAT/SRC/dtm [6l/

Enclosure '/

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Document Control Desk January 28,198F Page 2 cc: D. A. Brune, Esquire J. E, Silber g, Esquire R. A.Capra,NRC S. A.McNeil.NRC W. T. Russell, NRC D. C Trimble NRC R. J. Kiessel. NRC l

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ENCI.OSUR E (1)

FINAI, REPLY TO IE IlULI.ETIN 85-03 This letter provides the final information necessary to verify completion of all actions required by IE ilulletin 85 03. No hiotor-operated valses (htOVs) were found inoperable. Attachment A summarizes the data requested. The following notes apply to this data.

I. Test differential pressures (d/p) were the maximum obtainable in the test configuration (simulated accident condition). Full liigh Pressure Safety injection (llPSI) pump flow was directed into the Reactor Coolant System which was vented to the atmosphere, in fisc cases, the llPSI system was not capable of producing maximum design d/p (1310 psid sersus the 1313 psid required). For these cases the difference is considered insignificant.

2. The torque switch settings are explained in our response to Action item c. That is, the differences between test settings and final settings are discussed. No changes w ere required as a result of testing performed.

3. The Open To Close (*C') test d/p readings were taken with full flow and with valses fully open. Upon subsequent closing, the d/p's were measured and the maximum values were noted.

l The following discussion addresses each action item of IE Ilulletin 85-03 and our response. Additional information can be found in Reference (b) to the coser letter.

Asthn item x This item is complete. The results of this item were reported in Reference (a) and supplemented by Reference (c).

Acikn Item b:

A maintenance procedure exists at Cals ert Cliffs to control the set up, adjustment and testing of hlOV controls. This procedure includes torque switch, torque bypass switch and limit switch instructions. (Attachment !! provides the htOV Control Program at Cals ert Cliffs.) hiotor oserloads were established and controlled by electrical drawings. The initial switch settings and methods of control were established by the Architect / Engineer. This information w as prosided to Cah ert Cliffs in electrical drawings, control schemes and htOV Data Sheets. Ilecause of the procedures and documents as silable, the effort required for Action item b vonsisted primarily of serifying the sahdity cf historical switch settings listed in the htOV Data Sheets. This w as accomplished in house as follows: The required torque for each htOV w as determined using a method published by Limitorque in their htOY Selection Guides. Then we obtained from 1.imitorque correlations specific to the spring packs in>talled in our flulletin StOVs. These correlations related torque switch scale disisions (w hich are actui.ly a measure of spring pack deflection) to applied torque. Thus the required torque from l

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ENCI.OSUR E (1)

FINAL REPLY TO IE IlULLETIN 85-03 the calculation could be translated to a corresponding torque switch setting. A review of overloads had been conducted previously as recommended by IE Circular 81-13.

The calculational methodology was developed and the torque switch settings were derived in accordance with IE Bulletin 85-03. These newly derived settings were found to closely agree with the historical htOV Data Sheets' settings. No vai es were determined to be inoperable as a result of the calculations.

As11en item e-The htOVs subject to the requirements of the bulletin were tested at maximum d/p and full flow. These vah es were tested with 'as-found" switch settings. Additionally, the Unit One htOVs were tested at the reduced soltage of 432 solts (minimum 480-solt bus voltage allowed by Technical Specifications). All htOVs operated properly in both the open and shut directions. There were no obsersed problems.

No changes to the switch settings were required as a result of the testing, llowes er, as shown on Attachment A, some torque switch settings were changed. These were done to increase the conservatism in the settings. Some additional torque switch setting changes are planned just prior to the nest masimum d/p test. These changes will be made to standardire settings on similar htOVs in order to assist in long-term vah e i

performance trending.

Action Item d:

l As statd previously, the calculational method for determining torque switch settings j has been developed and procedures are in place to maintain torque switch, torque b> pass

, switch and limit switch settings, Some procedural enhancements were required to meet the intent of the bulletin, The control of torque switch settings for those htOVs subject to the requirements of the bulletin has been formalired. New procedures were I developed to perform masimum d/p testing of IE Dulletin 85 03 htOVs on a refueling inters al bails. We hase also developed post maintenance testing guidelines for the bulletin htOVs.

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ATTACIDtENT A  ;

VAI11C VAIA*E OIUWIOR If/F PASIS A P TIFTA P T/S 0 *IIsr T/S FIIIAL W1PJD U T l ',k S B U Ent GR IE g g 9 C 9 9 9 g I!171616 V GL P 34657 2 1500 -0025 1700 38.6:1 IJV 1295 1295 1340 1090 1.0 2.25 1.5 1.5

• 1117/617 V GL P 34657 2 1500 -0025 1700 38.6:1 IlV 1295 1295 1320 1110 2.25 1.75 1.5 1.5

• I!17/626 V CL P 34657 2 1500 -0025 1700 38.6:1 IJV 1295 1295 1340 1060 2.0 2.25 1.5 1.5

• Ifty/627 V GL P 34657 2 1500 -0025 1700 38.6:1 I2V 1295 1295 1320 1070 1.5 1.75 1.5 1.75 11171636 V GL P 34657 2 1500 -0025 1700 38.6:1 IJV 1295 1295 1330 1080 2.5 2.5 1.5 1.5

• 1177/637 V GL P 34657 2 1500 -0025 1700 38.6:1 IlV 1295 2295 1310 1100 1.5 1.5 1.5 1.5 If17/646 V CL P 34657 2 1500 -0025 1700 38.6:1 Ilv 1294 1294 1330 1040 1.75 2.75 1.5 1.5

• If11/647 V CL P 34657 2 1500 -0025 1700 38.6:1 IJV 1294 1294 1310 1040 2.5 1.5 1.5 1.5

• I!11/653 V CA P 34658 4 900 -0025 1700 36.2:1 IDIV 1313 1313 1310 390 1.0 1.0 1.5 1.5 1117/654 V CA P 34653 6 900 -040 1700 35.4:1 TIV 1313 1313 1330 360 2.25 2.5 3.0 3.0

]!17/655 V CA P 34653 4 900 -0025 1700 36.2:1 IDIV 1313 1313 1310 350 1.0 1.0 1.5 1.5

]!)J/656 V CA P 34653 6 1500 -160 3405 35.4:1 TIV 1313 1313 1310 350 2.25 2.25 2.25 2.25 2117/616 V GL P 34657 2 1500 -0025 1700 38.6:1 IJV 1295 1295 1325 940 1.5 1.5 1.5 1.5 2117J617 V GL P 34657 2 1500 -0025 1700 38.6:1 LIV 1295 1295 1320 950 1.5 1.5 1.5 1.5 2ftJJ626 V GL P 34657 2 1500 -0025 1700 38.6:1 LIV 1295 1295 1325 1060 1.5 1.5 1.5 1.5 2fff/627 V GL P 34657 2 1500 -0025 1700 28.6:1 LIV 1295 1295 1320 1070 1.5 1.5 1.5 1.5 2737/636 V GL P 34657 2 1500 -0025 1700 38.6:1 LIV 1295 1295 1325 980 1.5 1.25 1.5 1.25 2!171637 V GL P 34657 2 1500 -0025 1700 38.6:1 LIV 1295 1295 1310 1090 1.5 1.5 1.5 1.5 21111646 V GL P 34657 2 1500 -0025 1700 38.6:1 LIV 1294 1294 1320 1205 1.0 2.0 1.5 1.5 2!1T/647 V CL P 34657 2 1500 -0025 1700 38.6: 1 IlV 1294 1294 l'10 1180 1.0 2.0 1.5 1.5 2fff/653 V CA P 34658 4 900 -0025 1700 36.2:1 IDIV 1313 1313 1325 350 1.5 1.5 1.5 1.5 2ftJ/654 V CA P 34653 6 900 -040 1700 35.4:1 TIV 1313 1313 1340 350 2.25 2.25 3.0 3.0 2!)JJ655 V CA P 34653 4 900 -0025 1700 36.2:1 IDIV 1313 1313 1310 310 1.5 1.5 1.5 1.5 221J/656 V cA P 34653 6 1500 -160 1720 35.4:1 T1v 1313 1313 1310 305 2.25 2.25 2.25 2.25 VALVE VALVE _0111%70R J7.T JTUTAP T/S_EIIIAL

!! = IVJUFACIURIR  !! = JVJUFI.CIURIR 17.T = IXBIGi VAI1/E FUf3CTIQI O = CImED *I0 OPDT T/S = 'IOPQUE SUTICI V = VEIIJI IJL NtB LIIII*IUpr.3TE IJV = imp ISOIATIQi VALVE C = OPDI 'ID CImE O = 01111 T = TIIE 12m - IDIV = imp Da#GIRF1Ji ALL PRESSUIC III ISIG. C = CIME CL = GIDIE RIt! = 117IOR ISOIATIGI VALVE VAIA'E CimIIC ITESURES * = T/S 'ID IE CA = CATE Qt = GF1J1 PATIO TIV = 'Il%III ISOLATIGI VALVE IJE WrI11 FILM. AI1RUIID JUST S = SIZE III IIK3ff5 ALL VALVES IJE III 'IIIE IIIGI IRIOR *ID IID~r R = IFIf 7Jr/ PATI!C 11I Im. IMJIE SAFEI*I IJUECTIGI SYSTD1 APW ICL = ff]OEL 4

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A1TACllMENT Il CALVERTCLIFFS IE 11ULLETIN 85 03 MOTOR-OPERATED VALVE PROG RAM I. Method of MOV Control With a few exceptions, the normal industry practice is to seat the salve on action of the torque switch and to back seat the valve on action of the electrical limit switch. The rationale for this practice is to ensure tight l seating of the valve and a positive stop of the cperator on the back seat since i the back seat is the weakest mechanical part of the salve. This requires precise I torque switch and torque bypass switch setting determination and control. The consequences of inadequate torque switch and bypass switch settings are great.

Industry experience indicates that the itading causes of vahe fa.ilure er inoperability is the mis-adjustment or failure of the torque switch or its components. The torque switch is a spring centeled and balanced G vice. its ability to stay balanced and in adjustment is suspect. It is not a direct acting device, but depends upon the proper actions and calkration of the spring pack l The spring pack depends upon the proper grease and gap in the spring pack cavity and the suppression of hydraulic lock-up in the cevity. If the torque switch or i any of its components fail or are out of adjustment, or are installed I incorrectly, the resulting failure mode could be bent or broken s alve stems, burned out motors, valve seat damage, failures to operate, etc.

The Cahert Cliffs method of control substantially reduces these concerns because the torque switch is relegated to essentially a backup role for both opening and closing. The electrical limit switches are used as the primary control device for closing as well as opening. The limit switch is a less complex and a more positive acting device as it is directly geared to motor-operated drhe gests.

It does not depend on a spring pack. With vahe seating controlled by a limit switch, there is less wear on valv: and motor operated components because less force is being absorbed by the salve seat, valve stem, and operator gears. Also, because the sabe is not being ' torqued

• shut, less force is required to reopen the vahe.

The ditads antage of limit switch seating is that seat tightness may not be as uniform as with torque switch control. A ho, 'coastdown" of operator con.ponents must be allowed for. On closin g, the 'coastdow n' accomplishes the final seating after the limit switch stops the motor. On opening, 'coas tdo wn' has to be compensated for to present excesshe back seating. These disadsantages are os ercome by proper post adjustment operational checks. If a limit switch fails to operate (opening or clos.'g), then the torque switch will act to present vahe/ operator damage, The torque switch is also acthe during operation between i the open and close limits because of two train geared limit switches (i.e., limit I switch and torque L> pass switch operation occur simultaneously). This provides protection against binding and/or motor damage during trasel between the open and close limits.

At Cah ert Cliffs, litnit switch control has prosen to be a s alid method of control which has resulted in a good MOV operational history.

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ATTACitMENT B CALVERTCLIFF5 IE BULLETIN 85-03 MOTOR-OPERATED VALVE PROG RAM

11. Procedures for MOVs The Calvert Cliffs program consists of maintenance procedures, functional test procedures, preventive maintenance procedures, and operational procedures as follows:

- Maintenance Procedures: detailed disassembly /re-assembly instructions for various size motor operators.

- Functional Test Procedures: Contains instructions for limit switch, torque switch, tnd enrque bypass inspection and adjustment; ele:trical checks;.

post switch adjustment operational checks; motor current data; stroke timies; gives guidelines for post maintenance testing.

Preventive Maintenance Procedurer Mechanleal - Lubrication of operator; Electrical - Inspections, integrity checks, insulation resistance measurements.

- Operational Procedures: Full flow maximum differential pressure testing; stroke timing; neotor current data.

Ill. Post Mainsenance Testing of MOVs Written guidance is provided to ensure proper post maintenance testing is performed. This guidance specifies increasing levels of post maintensnee testing for a correspondingly increasing complexity of maintenance performed.

IV. Summary l The Calvert Cliffs program for IE Bulletin 85-0) MOVs combines limit switch l control with full differential pressure testing (on a refueling interval basis)

J to ensure MOV operability. The method of control has proven to proside reliable j MOV operation and has limited the maintenance required due to degradation of l

operators components. Full differential pressure testing of this bulletin's MOVs l under "as-found* conditions also serified the validity of this program.

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