ML19345G153
| ML19345G153 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 06/30/1975 |
| From: | Hartley F CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| CYH-3009, IEB-74-03, IEB-74-3, NUDOCS 8103060846 | |
| Download: ML19345G153 (3) | |
Text
'%-w-9 CONNECTICUT YANKEE ATO MIC POWER COMPANY
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HADDAM NECK PLANT M
RR # 1, BOX 127E, EAST AMPTON, CONN. 06424 Mn June 30, 1975 e f 1
CYH-3009 ir Jam s P. O'Reilly, Director
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C Division of Inspection and Enforcement
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U. S. Nuclear Regulatory Commission y%w
/[7 631 Park Avenue King of Prussia, Pennsylvania 19406
Dear Mr. O'Reilly:
The following report is submitted in accordance with Connecticut Yankee Atomic Power Company's Technical Specifications, Section "5.7.2 b",
Unusual Events.
Directorate of Regulatory Operations Bulletin (74-3,) " Failure of Structural or Seismic Support Bolts on Class I Components" was sent to Mr. D. C. Switzer on March 26, 1974. The bulletin requested that, "during your next scheduled outage, you selectively examine a representative portion of the vessel support members and structures, including the bolting material for two Seismic Category I vessels (as defined in Regulatory Guide 1.29) whose structural integrity is relied upon to withstand design and seismic displacements. This examination should include sufficient coverage of each support structure to provide confidence of serviceability."
The above examination was performed during the 1975 June refueling outage.
The pressurizer was one of the Seismic Class I vessels in the containcent selected for examination.
The lateral movement near the top of the pressurizer is restrained by four seismic restraints bolted to steel plates embedded into the charging floor. The design required 8 bolts (1 1/2" dia x 51/2" long) and two dowels to be installed. The examination revealed that only one of the four guides was installed properly (see drawing attached).
The other three guides did not line up properly with the embedded plates consequently only six of the eight bolts and only one of the two dowel pins were installed. The design called for lateral movement l
near the bottom of the pressurizer to be restrained by a ring girder bolted to the pressurizer and secured to the crane support wall. The examination revealed that 16 of the 24 bolts on the ring girder were never tightened enough to compress the lock washers.
The seismic restraints were reanalyzed to determine if the pressurizer seismic restraints would have failed if an earthquake actually occurred. lne reanalysis showed that a failure of the 7288 l
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Jun2 -30,1975
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.e-pressurizer seismic restraints would have occurred, however further analysis of the connecting piping would not be definitive in determining if any of the critical piping would have ruptured, therefore this was not pursued.
The pressurizer seismic restraints and their function are described in Section 2.5 of CY FDSA.
The analysis also showed that the seismic restraint capacity would be adequately restored with the addition of the missing dowels and the tightening of the lower support bolting the missing upper bolting was found not to be required.
Special Maintenance Procedure 10.5-42, Pressurizer Seismic Restraint Repair, was utilized to accomplish the installation of the missing dowels (3 dowels, one on ecch of 3 supports). The loose bolts on the ring grider were tightened as called for on the original drawing 10899-FS-35A and 35B.
Very truly yours, c.
7 F. W. Hartley Plant Superintendent RPT/jwa Attachment cc: Mr. A. Giambusso Deputy' Director for Reactor Projects Directorate of Licensing U. S. Nuclear Regulatory Commission Division of Inspection and Enforcement Washington, D.
C..
20545
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