ML20010J309
| ML20010J309 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 09/23/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8109300293 | |
| Download: ML20010J309 (2) | |
Text
_
400 Chestnut Street Tower II September 23, 1981 BLRD-50-438/81-07 BLRD-50-439/81-07 g
iact' Mr. James P. O'Reilly, Director SEP2 9 to; g % %u,%c's
- Office of Inspection and Enforcement
~j U.S. Nuclear Regulatory Coinnission C
N'85
}/
Region II - Suite 3100 U
101 Marietta Street Atlanta, Georgia 30303 (g
e vi
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - CORROSION OF CARBON STEEL PIPING - BLRD-50-438/81-07, -439/81 THIRD INTERIM REPORT The subject nonconformance was initially reported to NRC-0IE Inspector F. S. Cantrell on December 30, 1980 in accordance with 10 CFR 50.55(e) as NCR BLN NEB 8010. This was followed by our interim reports dated January 29 and May 22, 1981. Enclosed is our third interim report. This nonconformance has also been reported for Sequoyah and Watts Bar Nuclear Plants. We expect to submit our next report by November 18, 1981.
If you have any question, please call Dave Lambert at FTS 857-2561.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Enclosure cc:
Mr. Victor Stello, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555
((6 I /
$Ko$$$ofyg
^
ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 CORROSION OF CARBON STEEL PIPING BLRD-50-438/81-07, -439/81-07 10 CFR 50.55(e)
THIRD INTERIM REPORT Description of Condition It has been found that the original criteria for the use of carbon steel piping in raw water systems at TVA nuclear plants may not be adequate.
Corrosion has been found to cause greater than predicted pressure drops when pipes are sized according to standard industry practice.
In addition, the corrosion can cause a thinning of the pipe wall which may be in excess of the minimum wall thickness considered in the design of the systems.
This condition could affect all raw water systems with carbon steel piping, such as the ERCW System, High Precsure Fire Protection System, and the pump room and oil coolers for the centrifugal charging pumps, the safety injection pumps, and the containment spray pumps. Also, most electrical board and room air conditioning units use carbon steel piping.
The problem of corrosion has been the subject of considerable study at TVA.
A brief history of TVA's investigation of this matter was included in our first interim report.
Interim Progress Following Phase I of TVA's corrosion study, the Bellefonte ERCW System was reanalyzed using the interim criteria adopted at that time. Most of the resulting changes have been made.
In addition, TVA is approximately 90 percent complete with an additional ERCW System analysis using the final corrosion criteria defined in Mechanical Design Guide DG-M3 5, Revision 1.
Additional changes are anticipated as a result of the analysis based on DG-M3 5, Rev. 1.
As part of TVA's investigation of corrosion of carbon steel piping i
detailed in the report entitled " Corrosion in Carbon Steel Raw Water-Piping" (attached to a letter from L. M. Mills to J. P. O'Reilly dated August 25, 1981, for Sequoyah Nuclear Plant, NCR SQN NEB 8035), the average wall reduction of all samples was measured and found to be less than 0.040 inch except for a very few samples where exterior corrosion predominated because of' inadequate maintenance.
The design of all raw water piping on Bellefonte is such that an average wall reduction of 0.040 inch is acceptable.
Therefore, the effects of corrosion on the average wall reduction has been accounted for in the design of the systems.
Localized corrosion of piping may result in leaks in the systems. However, the anticipated rate of leakage would be quite small-in comparison to the rated flow of the system, and TVA plans to inspect and/or hydrotest the piping in accordance with ASME Section XI recuirements and will identify and repair any such leaks on a periodic basis.
T
-n n,-
..~a.
-e-
-n-r---
-