ML19323F114

Forwards LER 80-010/03L-0

ML19323F114
Person / Time
Site:	Cooper
Issue date:	05/08/1980
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19323F116	List: ML19323F114 ML19323F119
References
NUDOCS 8005280550
Download: ML19323F114 (2)

Text

f N COOPER NUCLEAR STATION e - , Nebraska Public Power District " * * "A*E" ORM;L*"O" "'"

- Ed1 CNSS899299 May 8, 1980 Mr. K. V. Seyfrit U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.4 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was discovered on April 8, 1980. A licensee event report form is also enclosed.

Report No.: 50-298-80-10 Report Date: May 8, 1980 Occurrence Date: April 8, 1980 Facility: Cooper Nuclear Station Brownville, Nebraska 68321 Identification of Occurrence:

Condition leading to operation in a degraded mode permitted by a limiting condition for operation as delineated in Section 3.6.G of .

the Technical Specifications.

Conditions Prior to Occurrence:

Reactor shutdown for scheduled refueling. ,

Description of Occurrence:

To comply with the required augmented inservice inspection program, a volumetric examination was performed on the Core Spray piping. A subsurface planar flaw approximately .2" by .45" was identified in weld CSB-BF-12 on the Core Spray Loop "B" piping.

Designation of Apparent Cause of Occurrence:

The apparent cause of the subsurface planar flaw in weld CSB-BF-12 has been attributed to an original construction defect. The defect was not visible by radiography. The probable cause for this defect not being detected during baseline inspection is that technique improvements during subsequent years,because of the need to detect Intergranular Stress Corrosion Cracking, has made the procedures used today much more sensitive.

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Mr. K. V. Seyfrit Ma* 8, 1980 Page 2.

Analysis of Occurrence:

The subject veld flaw is not related to Intergranular Stress Cor-rosion Cracking as evidenced by its mid wall location. Propagation is not anticipated in this type of flaw. However, had the flaw propagated to a through wall indication, drywell leakage measure-ment would have detected the failure. Due to the fact that stain-less piping exhibi:s large leakage before breaking, sufficient time would have existed to allow the reactor to be put in a safe con-dition. The weld is located inside of containment on the vessel side of the manual isolation valve and at an elevation above the core so that complete failure would not have uncovered the core.

This occurrence presented no adverse consequences from the stand-point of public health and safety.

Corrective Action:

In accordance with approved station procedures, the subsurface planar flaw of Core Spray weld CSB-BF-12 was removed, repaired, and surface and volumetric examinations performed as required by ASME Code. A pressure test will be performed in accordance with ASME,Section XI prior to startup.

Sincerely, L. C. Lessor .

l Str ion Superintendent Cotjer Nuclear Station LCL:cg ,

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