ML082530306

Vermont Yankee July 2008 Evidentiary Hearing - Applicant Exhibit E4-13-UY, INPO Report OE-17412 (Clinton)

ML082530306
Person / Time
Site:	Vermont Yankee, Clinton  File:NorthStar Vermont Yankee icon.png
Issue date:	08/12/2008
From:	- No Known Affiliation
To:	NRC/SECY/RAS
SECY RAS
References
06-849-03-LR, 50-271-LR, Entergy-Applicant-E4-13-VY, RAS M-328 OE17412
Download: ML082530306 (3)

Text

Subject:

0E17412 - (Preliminary) Pipe Damage Found to Cause High Condenser Air In-leakage Abstract:

While at 49% reactor power, during field investigation for the source of high Main Condenser air in-leakage (Off Gas flow rate), it was discovered that the continuous vent lines for both #2 feedwater heaters were leaking substantially due to pipe wall damage.

Reason for Message:

Communicate preliminary information for a large source of condenser air in-leakage.

Event Date: ............. 10/31/03 Unit Name: .............. Clinton NSSS/A-E: ............... General Electric / Sargent & Lundy Turbine Manufacturer: ... General Electric Maintenance Rule Applicability: No

==

Description:==

While at 49% reactor power, during field investigation for the source of high Main Condenser air in-leakage (Off Gas (OG) flow rate), it was discovered that the continuous vent lines for both #2 feedwater heaters were~leaking substantially due to pipe wall damage. The leaking point was located on pipes lDV07AA6 (heater #2A vent) and IDV07AB6 (heater #2B vent) at or near the condenser wall nozzle penetration. Because of the potential to exacerbate the problem the pipe insulation was not removed and therefore, the exact location is approximate. Temporary repairs to the pipe were performed over the insulation to seal the air in-leakage. Upon completion of the repairs the air in-leakage reduced from approximately 170 standard cubic feet per minute (scfm) to approximately 26 scfm, with the largest contribution from the #2B vent line (approximately 75% of the overall leakage). It is postulated that the damage or "hole" on these two pipes is due to flow erosion. A precise determination of the location and cause of damage should be done when permanent-repairs are performed and the pipes are examined in the next plant outage (February 2004). This discovery of in-leakage location occurred after a long campaign that began soon after the adverse trend in OG flow rate was noticed in late July 2003. Over that period the OG flow rate step-changed several times from 51 scfm on 07/23/03 to 165 scfm at the beginning of the down-power on 10/28/03.

DOCKETED Causes: USNRC A cause of damage will be performed during the next plant refueling outage (February 2004). August 12, 2008 (11:00am)

OFFICE OF SECRETARY Corrective Actions: RULEMAKINGS AND

1. The two pipes were temporarily repaired to continue plant ADJUDICATIONS STAFF operations.

2. Once damaged piping section has been examined and repaired /

replaced, a cause evaluation will be performed on this issue to determine causes, extent of condition, and required actidns going forward.

U.S. NUCLEAR REGULATORY COMIMISSON inthe Matter of NWJ49 VeM 3

?d .as (-

Docket No. I O-2-'7 Exhibit No. E(-I*,-'j official OFFERED bjtcaý Li Intervenor NRC Staff Other IDENTIFIED on027_L5,zWitness/Panel Action Taken: ,(ADM'rE REJECTED WITHDRAWN Reporter/Clerk"' C"-"

.4

Subject:

0E17412 - (Preliminary) Pipe Damage Found to Cause High Condenser Air In-leakage Please note that access to Nuclear Network is restricted to organizations authorized by INPO. The information exchanged via this network is confidential and for the sole use of the authorized organization. Confidentiality is important to ensure the open and frank exchange of information among authorized organizations.

Messages and other information on this web site should not be published, disclosed, abstracted, or otherwise transferred in any form to any third party, and their contents should not be made public without the prior written consent of INPO.

Information

Contact:

Roger Weber, Balance of Plant Manager 217-937-3835

_*RT TR ýTEDýD CO ýT