05000530/LER-2004-001, Re RCS Pressure Boundary Leakage Caused by Degraded Alloy 600 Component

Re RCS Pressure Boundary Leakage Caused by Degraded Alloy 600 Component

ML041270485
Person / Time
Site:	Palo Verde
Issue date:	04/29/2004
From:	Danni Smith Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 04-001-00
Download: ML041270485 (7)

LER-2004-001, Re RCS Pressure Boundary Leakage Caused by Degraded Alloy 600 Component

Event date:
Report date:
5302004001R00 - NRC Website

text

LAFS A subsidiary of Pinnacle West Capital Corporation Palo Verde Nuclear 1 OCFR50.73 Generating Station David M. Smith Plant Manager Nuclear Production Tel.

623-393-6116 Mail Station 7602 Fax.

623-393-6077 RO. Box 52034 e-mail: DSMITH10@apsc.com Phoenix, AZ 85072-2034 192-01138-DMS/SAB/DJS April 29, 2004 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Dear Sirs:

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 3 Docket No. STN 50-530 License No. NPF-74 Licensee Event Report 2004-001-00 Attached please find Licensee Event Report (LER) 50-530/2004-001-00 that has been prepared and submitted pursuant to 10CFR50.73. This LER reports the discovery and corrective actions taken as a result of reactor coolant system pressure boundary leakage caused by a degraded alloy 600 pressurizer heater sleeve. The degraded pressurizer heater sleeve was discovered during a short notice outage to repair the unit's electric generator. The pressurizer heater sleeve was repaired prior to Unit 3 resuming power operation.

The corrective actions described in this LER are not necessary to maintain compliance with regulations. Arizona Public Service Company makes no commitments in this letter.

In accordance with 10 CFR 50.73(d), copies of this LER are being forwarded to the NRC Regional Office, NRC Region IV and the Senior Resident Inspector. If you have questions regarding this submittal, please contact Daniel G. Marks, Section Leader, Regulatory Affairs, at (623) 393-6492.

Sincerely, DMS/SAB/DJS/kg Attachment cc:

B. S. Mallett M. B. Fields N. L. Salgado NRC Region IV Regional Administrator NRC NRR Project Manager + (send electronic and paper)

NRC Senior Resident Inspector for PVNGS

APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004

Abstract

On February 29, 2004 with Unit 3 in Mode 3, Hot Standby, engineering personnel discovered boric acid on a pressurizer heater sleeve while conducting a required boric acid walkdown.

The Unit had been shutdown and was being maintained in Mode 3 while trouble shooting a turbine-generator excitation problem. The cause of the boric acid leakage was attributed to primary water stress corrosion cracking of alloy 600 materials in the pressurizer heater sleeve. The amount of boric acid found was small.

The pressurizer heater sleeve was repaired using a mechanical nozzle seal assembly (MNSA).

Similar previous conditions of pressure boundary leakage were reported in LER 50-530/2003-002-00, LER 50-530/2001-003-00, and. LER 50-528/2001-001-00.

NRC FORM 366 (7.)

(If more space Is required, use additional copies of (If more space is required, use additional copies of (if more space Is requited, use additional copies of (if more space Is required, use additional copies of (if more space Is required, use additional copies of NRC Form 366A)

8.

PREVIOUS SIMILAR EVENTS

Similar previous conditions were reported in LER 50-530/2003-002-00, LER 50-530/2001-003-00, and LER 50-528/2001-001-00 in which different hot leg instrument nozzles and/or heater sleeves were found to have evidence of leakage (boric acid residue). Similarly, these conditions have been attributed to PWSCC and the nozzles/sleeves were repaired using an NRC-approved mechanical nozzle seal assembly (MNSA), and/or a permanent repair design.

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