ML17348A706
| ML17348A706 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 10/17/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17348A707 | List: |
| References | |
| NUDOCS 9011020100 | |
| Download: ML17348A706 (4) | |
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t UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 ENCLOSURE SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REVIEM OF RELIEF REQUEST REACTOR COOLANT PUMP EXAMINATION FLORIDA POWER 5 LIGHT COMPANY TURKEY POINT UNITS 3 AND 4 BACKGROUND Section XI of the ASME Code requires examination of one reactor coolant pump during each 10-year interval of plant operation.
By,letter (L-90-156) dated May 30, 1990, Florida Power 8 Light Company submitted a request for relief from the requirement for Turkey Point Units 3 and 4 and provided information in support of the request.
Pursuant to 10 CFR 50.55a(g)(6)(i), this information will be evaluated to determine if the requirement is impractical for the Turkey Point Units 3 and 4 facilities and relief from the requirement can be granted after the necessary findings are made.
RELIEF REQUEST Relief is requested from the Code volumetric and visual examinations of the reactor coolant pump casing welds and interior surfaces during the inspection interval.
Section XI Code Re uirements EXAM CATEGORY ITEM NO.
B-L-I B-L-2 B12.10 -
VOLUMETRIC EXAMINATION, to include 100K of the pressure retaining welds on one pump in each group of pumps performing similar functions in the system.
B12.20 -
VISUAL EXAMINATIONof the internal pressure boundary surfaces on one pump in each group of pumps performing similar functions in the system.
Bases for Relief Volumetric examination is not feasible due.to the coarse grain structure inherent in thick stainless steel
- castings, which precludes the use of conventi onal ultrasoni c examination techniques.
9011020100 901017 PDR ADOCK 05000250 F'DC
The pump casing is fabricated from cast stainless steel (ASTN A351, Grade CFSM) material.
Configuration of the pump design requires disassembly of the pump (including internal parts) to perform radiographic examination.
Visual examination is not practical since it requires total disassembly of the pump.
Radiographic examination is not possible without the complete disassembly of the pump.
To perform this examination, large expenditures of man-hours and man-rem are required with essentially no compensating increase in plant safety.
Based on actual data compiled from the radiographic examination of the Turkey Point Unit No.
3 reactor coolant pump casing welds and the visual examination of the internal boundary surface of one pump, in excess of 5900 man-hours and 46 man-rem exposure were expended in the disassembly, examinations and reassembly of the pump.
There is a very low probability, based upon industry experience, that there will be a need to disassemble the pump(s) solely for maintenance purposes.
There is no requirement by the pump manufacturer (Westinghouse) to disassemble the pump(s) as part of normal maintenance or inspection.
Accordingly, Florida Power 5 Light Company's procedures do not require disassembly of the pump(s) for maintenance or inspection purposes.
There are no reported failures in the pump casings with these model pump(s).
Adequate safety margins are inherent in the basic pump design.
The structural integrity afforded by the existing pump casing material will not significantly degrade over its lifetime.
The reactor coolant pump casing material, cast stainless steel (ASTM A351-CFBN), is widely used in the nuclear industry and has performed extremely well.
Satisfactory inspection results achieved in February 1982 coupled with the same inspections conducted by other utility companies and employing the same manufacturing model pumps, provide additional assurance as to the pumps'asing integrity.
Florida Power
& Light Company, through the Westinghouse Owners'roup, has submitted to the ASNE Code Committee, Code Case H-481, titled "Alternate Examination Requirements for Cast Austenitic Pump Casings."
This Code. Case was approved on March 5, 1990.
Alternative Examination Perform a VT-2 visual examination of the exterior of all pumps during the hydrostatic pressure tests required by Table IWB-2500-1, Category B-P.
Perform a VT-1 visual examination of the external surfaces of the weld of one, pump casing.
Perform a VT-3 visual examination of the internal surfaces whenever a
pump is disassembled for maintenance.
Im lementation Schedule for Unit 3 At or near the end of the inspection interval.
Inspection 'nterval 22 February 1984 to 21 February 1994 Inspection Period 22 February 1991 to 21 February 1994 Im lementation Schedule for Unit 4 At our near the end of the inspection interval.
Inspection Interval 15 April 1984 to 14 April 1994 Inspection Period 15 April 1991 to 14 Apt il 1994 EVALUATION The reactor coolant pumps at Turkey Point Units 3 and 4 are constructed of thick-wall cast stainless steel material.
Because of the high ultrasound attenuation characteristics of the material, a volumetric examination utilizing ultrasonics would produce meaningless results.
Because of the internal design of the pumps, removal of the motor and impeller would not provide access to the internal surface which is necessary for performing both radiographic and visual examinations.
Radiographic examinations have been performed on other pumps with similar designs and materials and with approximately the same age and accumulated operating time.
The data obtained from these examinations indicate no failures or reportable service-induced flaws in the pressure boundary material of the pumps.
In lieu of the required volumetric examination of the pump casing welds and visual examination of the internal surfaces, the licensee has proposed to perform 100K visual examination of the external surface and surface examination of a portion of the casing welds during the inspection interval.
CONCLUSION Based on the pumps'esign, materials of construction, and internal inaccessibility, the staff finds the examination requirements to be impractical to perform.
The licensee's proposed alternate examinations will provide a high degree of certainty of the pumps'tructural integrity.
The staff concludes that relief from the volumetric examination of the pump's casing welds and visual examination of the internal surfaces may be granted provided the proposed alternate examinations are substituted.
Pursuant to 10 CFR 50.55a(g)(6)(i),
the granting of this relief is author ized by law and will not endanger life or public property or the common defense and security and is otherwise in the public interest.
Dated:
Principal Contributor:
D. Se ers
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