ML040300239
| ML040300239 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  (NPF-041, NPF-051, NPF-074) |
| Issue date: | 01/22/2004 |
| From: | Mauldin D Arizona Public Service Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 102-05039-CDM/SAB/GAM, BL-03-001 | |
| Download: ML040300239 (2) | |
Text
id A F gNRC Bulletin 2003-01 David Mauldin Vice President Mail Station 7605 Palo Verde Nuclear Nuclear Engineering TEL (623) 393-5553 P.O. Box 52034 Generating Station and Support FAX (623) 393-6077 Phoenix, AZ 85072-2034 102-05039-CDM/SAB/GAM U. S. Nuclear Regulatory Commission January 22, 2004 ATTN: Document Control Desk Washington, DC 20555-0001
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529, and 50-530 Supplement to Response to NRC Bulletin 2003-01, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized Water Reactors" In a letter dated August 8, 2003 (letter no. 102-04983), Arizona Public Service Company (APS) submitted to the NRC the response to NRC Bulletin 2003-01, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized Water Reactors," for the Palo Verde Nuclear Generating Station (PVNGS), Units 1, 2, and 3. Since it is understood that Bulletin 2003-01 responses are still under review by the NRC, APS is submitting this letter to provide supplemental information related to APS'Bulletin 2003-01 response due to results of recent PVNGS containment sump inspections.
In the August 8, 2003 Bulletin 2003-01 response letter, APS stated that detailed inspections had been conducted in all three PVNGS units in response to NRC Information Notice 89-77, Supplement 1, and industry operating experiences, and that these inspections verified that no gaps existed between structural members and the fine screen that would permit passage of debris larger than the screen mesh size. The response also states that all penetrations into the sump were adequately equipped with collar devices or other barriers to ensure that no gaps existed that would permit larger debris to pass into the sump.
On December 2, 2003, after the Bulletin 2003-01 response was submitted, APS performed routine outage inspections of the containment sump screens in Unit 2.
During these inspections, a one-inch diameter hole was discovered in the top cover plate in each of the two containment sump screen structures. The one-inch holes (one in each sump cover pate) were larger than the screen mesh size of 0.09". The holes were plugged and subsequent sump inspections were conducted in Units 1 and 3.
No holes were found in the sump cover plates in Units 1 and 3, and the current containment sump configuration in all three units corresponds to their design.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance 0
Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Supplement to Response to NRC Bulletin 2003-01, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized Water Reactors" Page 2 Although the 1" holes in the Unit 2 containment sump cover plates were larger than the sump screen mesh size of 0.09", an engineering assessment has concluded that, due to the location of the holes in the top sump screen structure cover plates, transport of debris through the holes and into the ECCS and CS systems in event of a loss of coolant accident (LOCA) would have been unlikely. It has been determined that the holes resulted from the relocation of a sump fluid temperature detector conduit by a design change package implemented during initial Unit 2 plant construction in 1985.
The holes were apparently missed during previous containment sump inspections since these inspections concentrated on sump screen configuration and the annular gaps for existing conduits and piping.
This condition has been entered into the PVNGS corrective action program, and it has been concluded that this condition was not reportable under any reportability requirements. This condition was also discussed at the NRC Resident Inspector exit meeting at PVNGS on January 7, 2004, where the NRC Inspector discussed this condition as a proposed green non-cited violation for failure to maintain design control.
This proposed violation is expected it to be included in PVNGS Inspection Report 50-528/03-05; 50-529/03-05; 50-530/03-05.
No commitments are being made to the NRC by this letter. Should you have any questions, please contact Thomas N. Weber at (623) 393-5764.
Sincerely, CDM/SAB/GAM cc:
B. S. Mallett NRC Region IV Regional Administrator M. B. Fields NRC NRR Project Manager N. L. Salgado NRC Senior Resident Inspector for PVNGS