ML20082F430

Special Rept:On 950310,WR Noble Gas Effluent RM Failed Automatic Check Source.Monitor Has Repeatedly Failed mid- Range Check Sources,Causing Failed Automatic Check Source. Temporary Alteration Made to mid-range Channel

ML20082F430
Person / Time
Site:	Calvert Cliffs
Issue date:	04/07/1995
From:	Cruse C BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9504120118
Download: ML20082F430 (3)

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CHARLES H. CuvsE Baltknore Gas and Electnc Company

, Plant GeneralManager Calvert Clifs Nuclear Power Plant Calvert Clifs Nuclear Power Plant 1650 Calvert Chfs Parkway Lasby, Maryland 2065 7 410 586-2200 Ext.4tos Local 410 260-4101 Baltimore April 7,1995 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk SUllJECT- Calvert ClitTs Nuclear Power Plant Unit No.1; Docket No. 50-317 Unit i Wide Range Noble Gas Effluent Radiation Monitor Special Report in accordance with our Technical Specification 3.3.3.1, please find attached a Special Report concerning the Unit I Wide Range Noble Gas EfTluent Radiation Monitor.

Should you have questions regarding this matter, we will be pleased to discuss them with you.

Very truly yours, y Q A' s'-

CllC/RCG/bjd j Attachment ec D. A.13 rune, Esquire J. E. Silberg. Esquire L. B. Marsh, NRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC ]

l P. R. Wilson, NRC I R. I, McLean, DNR

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ATTACilMENT (1)

UNIT I WIDE RANGE NOBLE GAS EFFLUENT RADIATION MONITOR SPECIAli REPORT t

We submit this Special Report concerning an inoperable Wide Range Noble Gas Efl1uent Radiation Monitor (WRNGM) on the Unit I main vent stack' as required by Technical Specification 3.3.3.1,.

Table 3.3-6, item 2.b.i.  !

ACTION TAKEN i

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On March'10,1995, the WRNGM failed its automatic check source. Three manual check sources were pe formed in accordance with established plant procedures in an attempt to retum the WRNGM to service. l ARer three successive manual check source test failures, the monitor was declared inoperable at ,

t approximately 0320.

The WRNGM had been receiving random failures of the mid-range check source prior to March 10,1995.

Investigation into the root cause of the check- source failures is continuing. During preliminary ir,vestigations performed on February 21,1995 it was discovered that the mid-range channel aluminum foil  ;

pressure boundary between the detector and the sampic chamber was punctured. Through discussions with the equipment vendor, it determined that the mid-range detector would indicate an effluent reading higher than normal, i c., conservative, as a result of the puncture. Based on these discussions, an engineering l operability evaluation was completed on February 25,1995. The WRNGM was at that time determined to ,

be operable provided satisfactory mid range check sources, automatic or manual, could be performed. ,

v Additional investigation and analysis of the perforated aluminum foil pressure boundary was performed on '['

March 10,1995 while the WRNGM was out of scrdce due to the mid-range check source failure. At that time, the esisting operability evaluation was closed end the WRNGM was conversatively maintained out of service. l A temporary alteration was initiated to physically isolate and remove the mid-range channel from service and restore the WRNGM to operable status while utilizing the low and high range. channels to provide  ;

indication over the entire required range. ,

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EFFECT ON OPERATION Unit i Technical Speci6 cation 3.3.3.1 Action Statement (30) was entered when the WRNGM was removed from service. In accordance with this Action Statement and existing plant procedures, the main vent l radiatien monitor was used as the alternate preplanned main vent stack monitor for discharge flow stream ,

cfiluents. The WRNGM inoperability did not affect Unit 1 operation. ,

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CAUSES OF INOPERAnil.ITY

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The cause of the inoperability is repeated mid-range check source failures. Additional unresolved concerns over the ruptured aluminum foil pressure boundary of the mid-range detector chamber contributed to the )'

monitor being out of service greater than 7 days.

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1 ATTACllMENT (1)

UNIT I WIDE RANGE NOBLE GAS EFFLUENT

,. RADI ATION MONITOR SPECIAL REPORT PI,ANS AND SCIIEDULE FOR RESTORING Tile SYSTEM TO OPERAHLE STATUS The WRNGM was restored to OPERABLE status on March 28,1995 at approximately 1400 following implementation of a temporary alteration. Following repairs to the aluminum foil pressure boundary and determination of the root cause of the mid-range check source failures, the temporary alteration will be  :

removed and the WRNGM mid-range channel will be returned to service.

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