05000366/LER-1984-001, Revised LER 84-001-01:on 840203,plant Personnel Detected Fracture in 66-inch Vent Header in Bay 5.Caused by Brittle Fracture of Vent Header Matl.Vent Header Will Be Repaired Prior to Startup

Revised LER 84-001-01:on 840203,plant Personnel Detected Fracture in 66-inch Vent Header in Bay 5.Caused by Brittle Fracture of Vent Header Matl.Vent Header Will Be Repaired Prior to Startup

ML20087K336
Person / Time
Site:	Hatch
Issue date:	03/21/1984
From:	Nix H, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
GM-84-250, LER-84-001, LER-84-1, NUDOCS 8403260119
Download: ML20087K336 (6)

LER-2084-001, Revised LER 84-001-01:on 840203,plant Personnel Detected Fracture in 66-inch Vent Header in Bay 5.Caused by Brittle Fracture of Vent Header Matl.Vent Header Will Be Repaired Prior to Startup

Event date:
Report date:
3662084001R00 - NRC Website

text

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DOCKET NUGASEK (2) PAGE (3 SACILITV NAaAE (11 RDWIN I. HATCH, UNIT 2 ol5l0l0l0l3 6 l6 1 i jopl 0 l5 TITLE tel Fracture in vent header in torus EVENT DATE (S) LER NUMSER 161 REPORT DATE f., OTHER F ACILITIES INVOLVED !SI SIOU "

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NAME TELEPHONE NUMBER ARE A CODE Steven B. Tipps Superintendent of Regulatory Compliance 9;l [2 3l6l7 r 1 78p} 1 COMPLETE ONE LINE FOR EACM COMPONENT F AILURE DESCRinED IN TMiG REPORT 113l

" "' LE C- REPORTA CAUSE SYSTEM COMPONENT [ T NPR S CAUSE Sv511M COMPONENT y pq I B IS P IM I l X19 I 991 N l 1 ; I t i a0 I I I I I I I I I I i 1 I I SUPPLEMENTAL REPORT EKPECTED (14s MONTH DAY YgAR SUBMISSION VES (If yes, compiere RKPECTED Susneiss/OM DA m NO l l l A.eT R ACT a- M e mo =,, , . . , ,mm y .m .y.- . ,v-r,.. . i n ei Cn 02/03/84, during an inspection of the torus interior on Unit 2, plant personnel d2tected a fracture in a 66 inch vent header in bay 5. The total size of the fracture was approximately 26 square inches. The cause of this event is a brittle fracture of the vent header material. This fracture resulted from the vent header material being subjected to a temperature below its nil ductility temperature (NDT).

Since a nitrogen inerting system line is located directly above the vent header in the vicinity of the crack line, it is speculated that the inerting system was the cause cf the low temperature.

l Tho vent header will be repaired prior to startup. Additionally, procedure changes l cnd/or system modifications will be made, as necessary, to improve the operation of the nitrogen inerting system.

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NRC Pe.m 3084 U 8. NUCLEl.2 KETULATORY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATJON Arraoveo ows No mo-oio.

E x PIR E S 8/3195 FACILITY esaasE ill DOCKai NUWER (2) LLR NUMSf R 161 PAGE G "aa " C O. ",'Jo*.O EDWIN I. HATCH. UNIT 2 0 l5 l0 l0 l0 l 3l6 l 6 8l 4 Ol0 l 1 -

0l1 0l2 OF 0 l5 ren w m., . w.w. .msn.a.,we r = asuw nn REOUIREMENT FOR REPORT:

This report is required by 10CFR 50.73 (a)(2)(ii)(A)

PLANT CONDITIONS AT THE TIME OF THE EVENT (S):

On 02/03/84, at approximately 11:00 CST, Unit 2 was in cold shutdown fce the recirculation pipe replacement outage.

DETAILED DESCRIPTION OF THE EVENT (S):

On 02/03/84, during an inspection of Unit 2's torus interior, plant personnel detected a fracture in a 66 inch vent header in bay 5. The total size of the fracture was calculated to be approximately 26 square inches.

SUMMA'tY ASSESSMENT OF /.CTUAL AND POIENTIAL SAFETY CONSEQUENCES AND IMPLICATIONS:

An analysis by General Electric showed that if the size of the fr:cture (i.e., approximately 26 square inches) had remained the same, thsre would have been sufficient steam condensing capability had a Liss of Coolant Accident (LOCA) occurred. No analysis was performed to determine the consequences had the fracture size been greater.

STATUS OF REDUNDANT OR BACKUP SUBSYSTEMS AND/OR SYSTEMS:

Thsre is no backup system for the vent header.

JUSTIFICATION POR CONTINUED OPERATION:

The vent header will be repaired satisfactorily prior to unit startup.

IF REPETITIVE:

NUMBER OF PREVIOUS LER:

This is a non-repetitive event WHY CORRECTIVE ACTION DID NOT PREVENT RECURRENCE:

N/A HPACT TO OTHER SYSTEMS AND/OR UNIT:

This event did not affect other systems on Unit 2.

G;orgia Power Company management ordered Unit 1 to be placed in cold chutdown as a precautionary measure. The Unit 1 torus was inspected fce cracks and none were found. Unit 1 was then returned to normal cperation.

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CAUSE(S) OF THE NlVENTSLS):

The cause of this event is a brittle fracture of the vent header material. An examination of metal samples of the 66 inch vent header indicated that the fracture was caused by the vent header material bains subjected to a temperature below its nil ductility temperature (NDT). Since a nitrogen inerting system line is located directly cbove the vent header in the vicinity of the crack line, it was datermined that the inerting system was the cause of the low tcmperature to which the vent header was subjected.

Th3 plant has experienced set-point drift and maintenance problems with the nitrogen inerting system's lod temperature interlock switch (2T48-N075) for the nitrogen discharge isolation valve (2T48-F047). A cp;cific instance, which contributed to the low temperature problem, cccurred on August 9, 1983. On that date, the nitrogen inerting system's low temperature interlock switch (2T48-N075) for the nitrogen discharge isolation valve (2T48-F047) was detected as being inoperable dus to its wires being lifted. The date when the wires were lifted is unknown. However, on July 13, 1983, during a primary containment intetion, a decrease of 12 degrees Farenheit in the torus air tcperature was noted. With the wires lifted, the isolation valve would not have isolated the nitrogen supply at the O degree Fahrenheit sctpoint.

IMMEDIATE CORRECTIVE ACTION (S):

Tha vent header will be repaired prior to startup from the current l cutage.

SUPPLEMENTAL CORRECTIVE ACTION (S):

Pescedure changes have been made on Unit 1 to improve the procedural stsps involved with inerting the containment. The applicable Unit 2 procedures will be revised similarly prior to Unit 2 being inerted.

A Design Change Request has been initiated to re-route the existing nitrogen inerting system's piping, associated circuitry, and instrumentation. This piping is presently located directly above the v:nt header; this change will move the piping such that it will no lenger be above the vent header.

Also, due to poor maintenance history of the temperature switch , a Design Change Request was implemented providing a redundant isolation on low temperature.

SCHEDULED (FUTURE) CORRECTIVE ACTION (S'):

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ACTION (S) TO PREVENT RECURRENCE (IF DIFFERENT FROM CORRECTIVE ACTIONS):

Ths supplemental corrective actions should be sufficient to preclude escurrence of this event.

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. MASTER PARTS LIST NUMBER . INSTALLED BY . MODEL NUMBER .

. 2T23 . CHICAGO BRIDGE AND IRON . None .

. (Vent Header) . . .

l NIC FO*M 3864 09 434

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Coorgia Power Company a

• Post Offic) Bix 439 Baxiry. Georgb 31513 Telephone 912 367-7781 912 537-9444 GeorgiaPbwer Edwin 1. Hatch Nuclear Plant March 21, 1984 GM-84-250 r

PLANT E. I. HATCH Licensee Event Report Docket No. 50-366 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Attached is Licensee Event Report No. 50-366/1984-01, Rev. 1. This report is required by 10 CFR50.73 (a) (2) (ii) (A).

Af&-cM Nix / /

H. C.

General Manager

/

HCN/SBT/ ult xc: - R. J. Kelly R. E. Conway

'J. T. Beckham, Jr.

P. D.. Rice K. M. Gillespie S. B. Tipps R. D. Baker Control Room Document Control

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