ML13317B156

Forwards Request for Addl Info Re Degradation of Intake Structure & Insp of Accessible Areas of Structure

ML13317B156
Person / Time
Site:	San Onofre
Issue date:	08/13/1990
From:	Tatum J Office of Nuclear Reactor Regulation
To:	Ray H Southern California Edison Co
References
TAC-74168 NUDOCS 9008150113
Download: ML13317B156 (3)

Text

August 13, 1990 Docket No. 50-206 Mr. Harold B. Ray Senior Vice President Southern California Edison Company Irvine Operations Center 23 Parker Irvine, California 92718

SUBJECT:

INTAKE STRUCTURE DEGRADATION - SAN ONOFRE NUCLEAR GENERATING STATION, UNIT NO. 1 (TAC NO. 74168)

During the week of July 9, 1990, we met with members of your staff at the San Onofre site to discuss your assessment of the Unit 1 intake structure degradation and to inspect accessible areas of the intake structure. As a result of our discussions and our inspection, we have determined that the additional information identified in the enclosure to this letter is required to continue our review. Please provide your response to our request for additional information within 120 days of your receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under Pub. L.96-511.

Please contact us if you should have any questions regarding this request.

Sincerely, James E. Tatum, Project Manager Project Directorate V Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation

Enclosure:

Request for Additional Information cc w/enclosure:

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ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION RE:

INTAKE STRUCTURE DEGRADATION SAN ONOFRE NUCLEAR GENERATION STATION, UNIT 1 DOCKET NO. 50-206

1. Provide your assessment of the source of water appearing at the junction of South-West walls. Evaluate the consequences of sustained water leakage (ground-water) on the rebar and wall integrity.

2. A review of the construction drawings of the intake structure walls and slabs indicated that water-stops were not used at the wall-slab junctions. Evaluate the consequences of water passage (in-to-out or out-to-in) on the rebar and the long-term integrity of walls and slabs.

3. The procedures established for the ongoing inspection seem to be adequate. However, additional instruction should be provided for the inspection of underwater areas where the access is limited (underside of slabs, tunnels and joints between the pipe-tunnel and cast-in-place section), and for inspection of wall-slab junctions.

4. Provide information on ground-water chemistry (mainly chlorides, sulfates and ph-value) near the sea wall and near the pump support structure.

Also, provide your assessment of the effects of ground water seeping into the intake structure walls and slabs.

5. Provide information on the results of the chemical contaminant tests (chlorides, sulfates) of backfill soils. Also, provide your assessment of the effects of these contaminants leaching into the intake structure walls and slabs.

6. Identify those areas most likely to be susceptible to corrosion and degradation based on existing chloride levels and dissolved oxygen. More explanation (as discussed during the meeting) of the chloride penetration curves should be provided.

7. The 1986 inspection revealed some spot delamination of the top of the base slab. This indicates that chloride related corrosion may occur even in the constantly submerged structure. Evaluate this condition in the context of results from item 6 and discuss the vulnerability of other submerged areas.

8. The reinforcing plates are anchored to the concrete walls by means of Monel bolts.. They are likely to lose their preload due to relaxation and long-term surface degradation of the walls. Discuss the effectiveness of the bolts in assuring proper composite action when the preload is lost, or establish procedures which verify proper bolt preload during inspections.

9. Determine if NDE methods are currently available or will be available for evaluating the condition of concrete at depth, and your plans for implementing the use of such NDE methods.

Mr. Harold B. Ray San Onofre Nuclear Generating Southern California Edison Company Station, Unit No. 1 cc David R. Pigott Mr. F. B. Marsh, Project Manager Orrick, Herrington & Sutcliffe Bechtel Power Corporation 600 Montgomery Street P. 0. Box.60860 San Francisco, California 94111 Terminal Annex Los Angeles, California 90060 Mr. Robert G. Lacy Manager, Nuclear Mr. Phil Johnson San Diego Gas & Electric Company U.S. Nuclear Regulatory Commission P. 0. Box 1831 Region V San Diego, California 92112 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Resident Inspector/San Onofre NPS U.S. NRC P. 0. Box 4329 San Clemente, California 92672 Mayor City of San Clemente San Clemente, California 92672 Chairman Board of Supervisors County of San Diego 1600 Pacific Highway Room 335 San Diego, California 92101 Regional Administrator, Region V U.S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Mr. John Hickman Senior Health Physicist Environmental Radioactive Manaqement Unit Environmental Management Branch State Department of Health Services 714 P Street, Room 616 Sacramento, California 95814 Mr. Don Womeldorf Chief Environmental Management California Department of Health 714 P Street, Room 616 Sacramento, California 95814