05000263/LER-1984-011, Revised LER 84-011-01:on 840218,crack Indications Discovered in Listed Locations,Including RHR Sys & Recirculation Sys Pump Suction & Discharge Valves.Caused by Igscc.Stainless Steel 304 to Be Replaced

Revised LER 84-011-01:on 840218,crack Indications Discovered in Listed Locations,Including RHR Sys & Recirculation Sys Pump Suction & Discharge Valves.Caused by Igscc.Stainless Steel 304 to Be Replaced

ML20084R323
Person / Time
Site:	Monticello
Issue date:	05/15/1984
From:	Keller M, Musolf D NORTHERN STATES POWER CO.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
LER-84-011, LER-84-11, NUDOCS 8405220295
Download: ML20084R323 (3)

LER-2084-011, Revised LER 84-011-01:on 840218,crack Indications Discovered in Listed Locations,Including RHR Sys & Recirculation Sys Pump Suction & Discharge Valves.Caused by Igscc.Stainless Steel 304 to Be Replaced

Event date:
Report date:
2632084011R00 - NRC Website

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Crack indications have been found in the following locations:

1 Recirculation System Sensing Line Penetration Piping (previously reported in LER 84-011-00).

2. Residual Heat Removal System (previously reported in LER 84-011-00).

3. Recirculation System Pump Suction and Discharge Valves.

4. Recirculation System Discharge Riser "D" Safe End.

The degraded piping will be replaced with IGSCC resistant material. The valve material with indications will be machined so as to remove all affected material.

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0l1 01 2 0F 0 12 a a.e w me.w nn On February 18, 1984 and February 23, 1984 crack indications were detected on the B Loop Jet Pump (P) Instrument Seal (SEAL) and on both A&B Loops of the Residual Heat Removal (RHR) Low Pressure Coolant Injection (LPCI) lines. On April 13 and 14, 1984, crack indications were detected on the A Loop Recirculation Pump Discharge Valve (V) and the B Loop Recirculation Pnmp Section and Discharge Valves. On May 5, 1984 crack indications were detected on the B Loop Recirculation System Discharge Riser D Safe End-(PSF). All crack indications have been detected during normal Non-Destructive Examination activities for replacement of Recirculation System Piping (PSP). All cracks described above were detected while in cold shutdown.

All crack indications were located within the heat affected zone of welds to 304 Stainless Steel. B Loop Jet Pump Instrument Seal crack indications were located within the heat affected zone of a weld between two 304 Stainless Steel eccentric reducers. Indications appear to have been on the inside surface oriented parallel to the pipe axis. Crack indications on the A&B Loops of the RHR LPCI lines were located on the reactor side of the stainless steel LPCI testable check valves A0 10-46 A/B in the heat affected zone of welds joining a stainless steel pup piece to the valve and carbon steel piping. Indications on the Recirc Valves were located within the heat affected zone of welds to 304 Stainless Steel pipe.

Indications on the Riser D Safe End were located within the heat affected zone of the 304 Stainless Steel Safe End to Vessel Nozzle Weld.

All' detected crack indications are attributed to Intergranular Stress Corrosion Cracking (ICSCC). All susceptible 304 Stainless Steel is to be replaced with IGSCC resistant material. Welds to the valves and safe ends will be post weld heat treated using Induction Heating Stress Improvement techniques.

There have been two previous similar occurrences:

M-R0-82-13 Recire System ICSCC Problems A0-75-03 Recire Pump Bypass Line IGSCC Problems With the exception of one Thru-Wall crack on the Discharge Riser D Safe End, all indications have been found to be surface defects. There were no radioactive materials released and no personnel exposures or injuries took place. There was no effect upon public health or safety, l

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Northem States Power Company 414 Nicollet Mall Minneapoks. Minnesota 55401 Telephone (612) 330-5500 May 15, 1984 U S Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Revised Licensee Event Report Related to Crack Indications on Primary System Pressure Boundary A revised Licensee Event Report for this occurrence is attached.

These events were reported via the Emergency Notification System per 10 CFR Part 72 on February 18, February 23, April 13, April 14, and May 7, 1984.

DJ David Musolf w.b Manager - Nuclear Support Services cc: Regional Administrator - III, NRC NRR Project Manager, NRC Resident Inspector, h1C MPCA Attn: J W Ferman Attachment ff

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