ML17334B674

LER 97-009-00:on 971126,blockage of Containment Air Recirculation Inlet Line Was Noted.Caused by Concrete Which Entered Line During Repair.Blockage Was Removed & Procedures Were Implemented to Preclude Future blockages.W/971224 Ltr

ML17334B674
Person / Time
Site:	Cook
Issue date:	12/24/1997
From:	Blind A, Schoepf P INDIANA MICHIGAN POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-97-009-01, LER-97-9-1, NUDOCS 9801020028
Download: ML17334B674 (5)

Text

CATEGORY REGUL RY INFORMATION DZSTRIBUT SYSTEM (RIDS)

ACCESSION NBR:9801020028 DOC.DATE: 97/12/24 NOTARIZED: NO DOCKET FACIL:50-316 Donald C. Cook Nuclear Power Plant, Unit 2, Indiana M 05000316 AUTH.NAME AUTHOR AFFILIATION SCHOEPF,P. Indiana Michigan Power Co.

BLIND,A.A. Indiana Michigan Power Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 97-009-00:on 971126,blockage of containment air recirculation inlet line was noted. Caused by concrete which entered line during repair. Blockage was removed &, procedures were implemented to preclude future blockages.W/971224 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc. E NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD3-3 PD 1 1 HICKMAN,J 1 1 INTERNAL: 2 2 AEOD/SPD/RRAB 1 1 FILE CENT 1 1 NRR/DE/ECGB 1 1 B 1 1 NRR/DE/EMEB 1' NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DET/EIB 1 1 RGN3 FILE 01 1 1 D

EXTERNAL: L ST LOBBY WARD 1 1 LZTCO BRYCE,J H 1 1 0 NOAC POORE,W. 1 1 NOAC QUEENER,DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 U

E N

NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 24 ENCL 24

Indiana Michigan Power Company Cookhfudear Plant One Cook Place

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Bridgman, Ml 49t06 INI)MNA NICHIOiAN POIVKR December 24, 1997 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Operating Licenses DPR-74 Docket No. 50-316 Document Control Manager:

b ib b i

'b b by m the following report is being submitted:

97-009-00 Sincerely, A. A. Blind Site Vice President

/mbd Attachment A. B. Beach, Region III E. E.. Fitzpatrick P. A. Barrett S. J. Brewer J. R. Padgett D. Hahn Records Center, INPO NRC Resident Inspector

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I illilllffflllllllfllllflllflfllllllllfl PDR ADOCK 050003 S

NRC FORM 366 PPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEH PER RESPONSE TO COMPLY WITH TMI INFORMATION COLLECTION REQUEST: 50.0 MRS. FORWAR LICENSEE EVENT REPORT (LER) COMMENTS REGARDING BURDEN ESTIMATE TO TH INFORMATION AND RECORDS MANAGEMENT BRANCH (HNB 7714), U.S. HUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWOR REDUCTION PROJECT (3150 0104), OFFICE 0 HANAGEMENT AND BUDGET WASHINGTON DC 20503.

FACILITY NAME (1) DOCKET NUHBER (2) Page1 of3 Donaid C. Cook Nuclear Plant - Unit 2 50-316 TITLE (4)

Blockage of Containment Air Recirculation Inlet Line Results in Condition Outside Design Bases SEQUENTIAL REVISION FACILITY NAME DOCKET NUMBER MOHTM DAY YEAR YEAR MONTH DAY NUHBER NUMBER None FACILITY HAME DOCKET NUMBER 26 97 97 009 00 12 24 OPERATING MODE (9) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(iii) 73.71(b)

POWER 0

LEVEL (10) 20 '203(a)(2)(i) 20.2203(a)(4) 50.73(a)(2)(v) OTHER (Specify in 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(viii)(A) Abstract below 20.2203(a)(2)(iv) 50.73(a)(2)(i) 50.73(a)(2)(viii)(B) and in Text, 20.2203(a)(2)(v) X 50.73(a)(2)(ii) 50.73(a)(2)(x) NRC Form 366A)

NAHE TELEPHONE NUMBER (Include Area Code)

Mr. Paul Schoepf, Safety Related Mechanical Engineering Superintendent 616/465-5901, x2408 REPORTABLE REPORT'ABLE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONEHT MANUFACTURER TO NPRDS TO NPRDS EXPECI'ED SUBHISSION YES X NO DATE 15 ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

During a foreign material exclusion inspection conducted on November 26, 1997, one of two Train B inlet lines for the hydrogen removal and air recirculation from the Unit 2 number 2 and 3 Steam Generator enclosures was found to have been blocked by concrete. The condition was reported under the provisions of 10CFR50.72(b)(2)(i) on November 30, 1997.

The blockage occurred during the Unit 2 Steam Generator replacement in 1988. During this time, portions of the Steam Generator enclosure structure were removed to allow access to the Steam Generators. Following the replacement, the structures were reconstructed. It is believed that the concrete entered the line during the repair of the structure. The blockage has been removed, and procedures will be implemerited to preclude future blockages of these lines.

An evaluation of the impact of the blockage has concluded that there would have been adequate flow through the Steam Generator enclosure to preclude excessive accumulation of hydrogen. Thus, the condition did not present a significant risk to the health and safety of the public.

NRC FORM 366A PPROVED BY OMB NO. 3150-0104 EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY 'WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

LICENSEE EVENT CONTINUATION FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY'COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150.0104), OFFICE OF MANAGEMENl'ND BUDGET liASHINGTON DC 20503.

YEAR SEQUENTIAL REVISION Cook Nuclear Plant - Unit 2 50416 97 009 00 2OF3 TEXT (if more space is required. use additional NRC Form 366A's) (I7)

C ndi's Pri r o Eve Unit 2 was in Mode 6, Refueling D cr'o of the Ev During a foreign. material exclusion inspection conducted on November 26, 1997, it was discovered that one of two Train B inlet lines for hydrogen removal and air recirculation from the Unit 2 number 2 and 3 Steam Generator enclosures had been sealed sometime in the past. This was reported under the provisions of 10CFR50.72(b)(2)(i) on November 30, 1997.

The air recirculation system at the Cook Nuclear Plant is designed to circulate air from the upper containment to the lower containment as a means of distributing hydrogen generated as a result of an accident. By distributing the hydrogen throughout the containment, the hydrogen concentration at any single location can be maintained below 4 volume per cent. The majority of the air circulated is drawn from the upper containment by the recirculation fan (EIIS/BB), fiows into lower containment, and is returned to the upper containment through the ice condenser. A small portion of the flow, however, is diverted from the lower containment to the "hydrogen skimmer system" which draws air from the pressurizer compartment, the Steam Generator compartments, and the instrument room, removing hydrogen from these areas.

Steam Generator compartments 2 and 3 each have two inlet pipes to the hydrogen skimmer system (Train A and B).

Additionally, the compartments are interconnected by openings in the wall between them. Assuming a single active failure of Train A, with one inlet pipe for Train B blocked, the flow through the two Steam Generators would have been approximately one half of the design flow of 500 cfm. This flow is being'confirmed by test.

The blocking of the duct is believed to have occurred during the Unit 2 Steam Generator replacement project in 1988, during which the Steam Generator enclosure was demolished and restored. Most likely, while pouring the concrete over the forming plate used to form the new Steam Generator enclosure roof, concrete filled the existing penetration.

The blockage went undetected because the current surveillance procedures do not measure flow through the system.

Rather, the surveillances check for fan operation, backdraft damper operation, suction valve operation, and position of fixed dampers in the system.

als v This event is reportable under the provisions of 10CFR50.73(a)(2)(i)(B), operation prohibited by the plant's technical specifications, and 10CFR50.73(a)(2)(ii)(B), a condition which is outside the design basis of the plant.

The production of hydrogen inside the containment following a loss of coolant accident occurs due to water radiolysis and metal corrosion. The prime contributors to metal corrosion generated hydrogen are aluminum and zinc, both of which have high corrosion rates when exposed to alkaline solutions. Inside the containment, these metals would come into contact with an alkaline solution though submergence in the water which accumulates inside the containment or by contact with the solution being sprayed inside containment via the containment spray system.

NRC FORM 366A PPROVED BY OMB NO. 3150-0104 EXP IRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS.

LICENSEE EVENT CONTINUATION FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION,

'WASHINGTON DC 20555 0001 ~ AND TO THE PAPERWORK REDUCTION PROJECT (3150 0104), OFFICE OF MANAGEMENT AND BUDGET WASHINGTON DC 20503.

YEAR SEQUENTIAL REVISION Cook Nuclear Plant - Unit 2 50416 97 009 00 3OF3 TEXT (if more space >s required. use additional NRC Fom 366A's) (I7)

Anal sis of the Event cont'd There are no spray nozzles inside the Steam Generator compartments, and the compartments do not fill with water following the floodup of the containment. Therefore, the hydrogen generated in the lower containment occurs outside of the Steam Generator compartment, and it is well mixed with the air (nominal value of 40000 cfm) being circulated through the lower compartment by the recirculation fan. Thus, there is little potential for significant amounts of hydrogen to accumulate in the Steam Generator compartment, even with reduced flow, because the principal source of hydrogen entering the Steam Generator compartment is flow from the well mixed portion of the lower containment.

The hydrogen skimmer system is composed of two trains, and except for short periods of time when a train may have been removed for maintenance within an Technical Specification Action Statement, the redundant system would have been available, and it would have been capable of providing the design flow.

The concrete was removed from the pipe. Additionally, every branch of both the Unit 1 and Unit 2 hydrogen skimmer systems was inspected. No additional plugging was found.

A test will be conducted on both Unit 1 and Unit 2 prior to startup to confirm that required air flows are achieved.

These tests will also measure the air flow through the Unit 2 Steam Generator number 2 and 3 compartment, in the as-found condition.

The lessons learned from this event will be forwarded to the Unit 1 Steam Generator replacement project, and post maintenance testing of the hydrogen skimmer system will be incorporated into that project's procedures.

Failed Com onent tdentlflcatlon Not applicable Previous Si ilar Events None