ML18046B169
| ML18046B169 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 12/21/1981 |
| From: | Vincent R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-03.C, TASK-3-3.C, TASK-RR NUDOCS 8112280453 | |
| Download: ML18046B169 (5) | |
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~©JITTJiJ~rIDITllW General Offices: 212 West Michigan Avenue, Jackson, Ml 49201 * (517) 788-0550 December 21, 1981 Dennis M Crutchfield, Chief Nuclear Reactor Regulation Operating Reactors Branch No 5 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - SEP TOPIC III-3.C, INSERVICE INSPECTION OF WATER CONTROL STRUCTURES Enclosed is Consumers Power Company assessment of SEP Topic III-3.C for the Palisades Plant.
This topic assessment is based on the NRC topic assessment provided for San Onofre Unit 1 (NRC letter of July 27~ 1981).
In general, Palisades does not have dams, bulkheads, culverts, etc. to which this topic might apply.
The only portion of the plant which is affected concerns the intake structure and pipe.
The scope of the topic evaluation, therefore, has been limited to only the applicable structures.
Consumers Power Company's conclusion regarding the assessment is that, al though inspections of the water control stuctures made heretofore have resulted in proper maintenance of the structures and have resulted in a continuously available supply of service water, no formal program or record of inspections has been made.
The need to formalize an inspection program should be addressed in the Palisades Integrated Assessment.
Robert A Vincent Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector-Palisades ATTACHMENT
SYSTEMATIC EVALUATION PROGRAM TOPIC III-3.C ASSESSMENT INSERVICE INSPECTION OF WATER CONTROL STRUCTURES PALISADES NUCLEAR POWER STATION SUBJECT HEADINGS I.
INTRODUCTION II.
REFERENCES AND RELATED TOPICS III.
DESCRIPTION OF WATER CONTROL STRUCTURES IV.
AVAILABILITY OF DATA V.
INSPECTIONS VI.
TECHNICAL EVALUATION VII.
CONCLUSIONS VIII.
EVALUATION PROCEDURE I L
SYSTEMATIC EVALUATION PROGRAM TOPIC III-3.C ASSESSMENT
- INSERVICE INSPECTION OF WATER CONTROL STRUCTURES PALISADES NUCLEAR POWER STATION I.
Introduction The purpose of the review of this SEP Topic is to assess the adequacy of the programmed inspections of the submerged intake crib, buried steel pipeline and onshore reinforced concrete intake structure to assure conformance with the requirements and intent of Regulatory Guide 1.127, Inspection of Water Control Structures Associated with Nuclear Power Plants.
The intent of R.G. 1.127 is to assure that water control structures of a nuclear facility are adequately inspected to insure the capability and integrity of those systems, the failure of which could cause radiological consequences adversely affecting the public health and safety.
II.
References and Related Topics R.G. 1.127 SEP Topic IX-3 Station Service and Cooling Water Systems SEP Topic XVI Technical Specifications III.
Description of Water Control Structures The water control structures at the Palisades Plant which are included under Topic III-3.C are the intake crib, the pipeline and the intake structure.
The crib structure is located in about 30 feet of water, 3150 feet offshore.
It is constructed of heavy structural steel members which form a framework bolted to 22 heavy wall pipe columns each 24 inches in diameter which support the structure over the vertical pipe intake bell.
The structure is cross braced at all panels.
Piles, HP 12 X 53, are driven down through each pipe support column to a depth approximately 100 feet below the top of the crib and are then cut flush with the top deck plate and grouted within the pipe with tremie concrete.
The top deck grillage consists of six-inch steel beams spaced on 22-1/2 inch centers and covered with 3/8-inch plate.
The sides of the crib are closed with vertical racks with tubular bars spaced at approx-imately 11 inches.
The top deck is approximately 20 feet below mean low water level in Lake Michigan.
The intake pipe bell is located above a mounded structure of riprap and cement-filled sacks.
The intake pipe is 11 feet in diameter and constructed of heavy-wall, steel bell and spigot pipe sections.
This pipe drops below the bell inlet to an elbow beneath the floor of the lake and then is buried in a trench backfilled by selected stone material from the intake crib to the concrete intake structure on shore.
The 11-foot diameter pipe bifurcates to 100-foot long, 8-foot diameter pipes serving the two bays of the intake structure:
The total length of the pipeline is 3350 feet.
2 III.
Description of Water Control Structures (Can't)
The reinforced concrete intake structure controls the water approach to the three service water pumps.
This structure is furnished with traveling screens and stop logs.
Each bay can be isolated from the other for maintenance purposes.
The structures were originally designed to provide 390,000 gpm cooling water to the condenser on a once-through basis plus service water flow.
However, the installation of cooling towers at the site reduced the role of the water control structures to that of providing only 16,000 gpm service water and 60,000 gpm dilution water flow.
IV.
Availability of Data The drawings of the water control structures and construction photographs are available at the site.
Photographs taken dliring underwater inspections of the structures are also available for use during future inspections.
V.
Inspections The present intake crib structure, which replaced the original crib destroyed by ice, was inspected by divers the first year following its installation at which time no structural damage was found.
Subsequent to that inspection an inspection of the pipeline revealed a heaV:y deposition of sand which was later removed.
Inspection of the concrete intake structure for functionability is made by operators on a non-formal basis.
The intake structure screens have had one underwater inspection when they malfunctioned.
At that time sand deposits were noted in the concrete intake structure and were subsequently removed.
In 1981 a heavy deposit of sand was again noted in the intake structure and was again removed.
Also, the inspectors found up to three feet of sand in the bifurcate~ intake pipes.
This reduction of flow area in the structures does not affect the capability of the water control structures to furnish the small a.mount of water reg_uired by the service water pumps.
That is, the system was originally designed for 390,000 gpm circulating water flow.
After the cooling towers were added the normal flow in the system was reduced to approximately 76,000 gpm.
Consisting of:
Dilution Water Flow Service Water Flo~
Total
= 60,000 gpm
= 16,ooo gpm
= 76,000 gpm If an accident were to occur the flow would be reduced to the service water flow only.
Thus emergency flow is always assured due to normal flow being over three times greater than required under accident condi-tions.
None of the above inspections were made under a formal program of inspections.
l.*
3 VI.
Technical Evaluation There is no formalized program of inspection of the structures.
Never-theless, the inspections that are made and which are ordered based on observations by the operating personnel have resulted in proper maintenance of the water passages.
The structures are of massive construction and protected by submergence or burial from usual atmospheric events.
The possibility that frazil ice could cause a stoppage exists but such an event could not be anticipated as a result of an earlier inspection of the structure.
Damage to the crib structure due to heavy ice floes is a possibility although such damage is not expected to cause a stoppage of the service water flow.
The original crib was severely damaged by a combination of ice and wave action.
Consequently, the present crib structure was designed to withstand substantially greater forces., However, the possibility of progressive damage over the years can not be ruled out.
VII.
Conclusion A program of inspecting the intake crib structure would insure that the intent of R.G. 1.127 would be met at the Palisades Plant.
Experience gained through ten years of operation will permit the formulation of a practical schedule for inspection in the detail required to assure con-tinuity of operation of the facility through timely maintenance.
Consideration will be given to adding routine intake structure and pipe inspections on a formal basis to the plant Preventive Maintenance Program.