ML13317B204
| ML13317B204 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/19/1990 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9010250242 | |
| Download: ML13317B204 (2) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 htober 19, 1990 R.M.ROSENBLUM TELEPHONE MANAGER OF (714) 587-5420 NUCLEAR REGULATORY AFFAIRS U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket No. 50-206 Verification of Pressurizer Integrity San Onofre Nuclear Generating Station Unit 1 In response to an NRC request, this letter forwards the results of a visual inspection of the internal clad surface of the San Onofre Unit 1 pressurizer.
This inspection was the result of the discovery of hairline cracks in the Haddam Neck pressurizer, which is of similar design to the San Onofre Unit 1 pressurizer.
On June 12, 1990, our NRC Project Manager discussed the Haddam Neck experience with members of our staff at San Onofre. Based on these discussions, we performed a visual inspection of the internal clad surface of the Unit 1 pressurizer while the unit was shut down for the reactor thermal shield support replacement. No evidence of clad cracking was found.
By a letter dated July 30, 1990, you emphasized the importance of pressurizer integrity to plant safety. In addition, you requested a description of the actions that we have taken to address your concern and our assessment of the current state of the Unit 1 pressurizer integrity. You requested this information prior to return to service from the current refueling outage.
The enclosed report entitled "Verification of Pressurizer Integrity" contains the information which you requested. It concludes that the integrity of the San Onofre Unit 1 pressurizer is satisfactory and no further action is required.
If you have any questions, please call me.
Very truly yours,
-Q F 'DC Enclosure cc: J. B. Martin, Regional Administrator, NRC Region V C. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3
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VERIFICATION OF PRESSURIZER INTEGRITY SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 1 Southern California Edison Company was notified by the NRC in early June of the results of internal visual inspection of the pressurizer at the Haddam Neck plant. In this inspection, the licensee, Connecticut Yankee Atomic Power Company, discovered a multitude of hairline cracks in the cladding in the vicinity of the lower head. Further examinations from the outside indicated that three of the cracks had penetrated through the cladding into the pressurizer base metal.
One of these three cracks required detailed analysis to satisfy ASME Code requirements for resolution.
Since the San Onofre Unit 1 pressurizer is very similar in design to the Haddam Neck pressurizer, a remote visual inspection of the internal clad surface of the Unit 1 pressurizer was performed during the current thermal shield repair outage. The areas examined were the lower head in the vicinity of the surge nozzle, numerous heater penetration welds, the upper and lower heater support plates, and the accessible regions of the vessel wall between the heater support plates. No evidence of clad cracking was noted during the inspection. A videotape record of the inspection was made during its performance. A copy of the videotape of the examination was furnished to the USNRC personnel during a visit to San Onofre on July 10, 1990. These results were appropriately documented and verified by the SCE NQC inspector.
(This inspection also satisfied the inservice inspection requirements of Table IWB-2500 of Section XI of the ASME Code (1974 edition).
Inspection Category B-I-2, "Interior Clad Surfaces of Vessels Other Than Reactor Vessels," in this table requires that at least one clad patch of 36 square inches be visually examined at each pressurizer inspection interval.)
Based on the inspection results, it is concluded that the integrity of the San Onofre Unit 1 pressurizer is satisfactory and no further action is required.