ML18046B259

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Forwards Final Evaluation of SEP Topic III-10.B Re Pump Flywheel Integrity
ML18046B259
Person / Time
Site: Palisades Entergy icon.png
Issue date: 02/02/1982
From: Wambach T
Office of Nuclear Reactor Regulation
To: Hoffman D
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
References
TASK-03-10.B, TASK-3-10.B, TASK-RR LSO5-82-02-014, LSO5-82-2-14, NUDOCS 8202090278
Download: ML18046B259 (6)
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{{#Wiki_filter:r-, - Docket No. 50-255 LS05-82-02-0l 4 Mr. David P. Hoffman Nuclear Licensing Administrator Consumers Power Company 1945 W. Parna 11 Road Jackson, Michigan 49201

Dear Mr. Hoffman:

February 2, 1982

SUBJECT:

COMPLETION OF TOPIC III-10.B - PUMP FLYWHEEL INTEGRITY -- PALISADES Enclosed is a copM of our final evaluation of Systematic Evaluation Pripgram Topic III-10.B. This report has been revised to reflect the comments con-tained in your letter of July 2, 1981. With this revised evaluation our review of SEP Topic III-10.B is complete and will be a basic input to the integrated assessment of your facility. The subject assessment compares your facility design with the criteria cur-rently used by the staff in licensing new facilities. This assessment may need to be re-examined if you modify your facility or i.f the criteria are changed before we complete our integrated assessment.

Enclosure:

As stated cc w/enclosure: See next page 8202090278 820202 PDR ADOCK 05000255 P PDR. Sincerely, Thomas V. Wambach, Project Manager Operating Reactors Branch No. 5 S,fo'f Division of Licensing ~/ ,, /' b!; '4. IJ b ( OC/) Aov: ~~ s/. *.!1 T. tl/\\:Ju~~ OFFICE *** $.E:.P.B.~.. SURNAME *** P.X~Q... D.:.l?.1..... ... S~P.~... ~L..... ~?.~.... $.:........ 0.. 6.il.~.............QR...... ~1\\;JlL...... RH~r:~~-~.n........ ~R~~--. .T.~.~m~.~£D....... P.~r..... s.... J.~J.~.. ~. ~-~.n~.?......... ************************ DATE **** J./(}.~J.e.?........./.l..~.~l~g........./.. l.fl.1.1.§.~........ 2.1.A.I.?.?......... 11.J... 1.§6.......... ~.!..+./.?.?............................... NRC FORM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY USGPO: 1981-335-960

---~--* *-. *-----*--**--___ '1 'i .. '-i-----*-*.- 9, Mr. David P. Hoffman cc. M. I. Miller, Esquire Isham, Lincoln & Beale Suite 4200 One First National Plaza Chi ca go; I 11 i noi s 60670 Mr. Paul A. Perry, Secretary Consumers Power Company 212 West Michigan Avenue

  • Jackson, Michigan 49201 Judd L. Bacon, Esquire Consumers Power Company 212 West Michigan Avenue Jackson~ Michigan 49201 Myron M. Cherry, Esquire Suite 4501 One lBM Plaza
  • Chicago, IllinoiS 60611 Ms. Mary P. Sinclair Great Lakes Energy Alliance 5711 Summerset Drive

. Midland, Michigan 48640 Kalamazoo Public Library 315 South Rose Street Kalamazoo, Michigan 49006 Township Supervisor Covert Township Route 1, Box 10 Van Buren County, Michigan Office of the Governor (2) Room 1 - Capitol Building Lansing, Michigan.48913 William J. Scanlon, Esquire 2034 Pauline Boulevard* Ann Arbor, Michigan_ 48103 Palisades Plant ATTN: Mr. Robert Montross Plant Manager Covert, Michigan 49043 49043 PALISADES Docket No. 50-255 U. S. Environmental Protection Agency Federal Activities Branch Region V Offic*. ATTN: EIS COORDINATOR 230 South Dearborn Street Chicago, Illinois 60604 Charles Bechhoefer, Esq., Chairman Atomic Safety and Licensing Board Panel

u. S. Nuclear Regulatory Commission.-

Washington, D~ C~ 20555

  • Dr. George C. Anderson Department of Oceanography University of Washington Seattle, Washington 98195 Dr. M~ Stanley Liv.ingston*

1005-Calle Largo Santa Fe, New Mexico 87501 R*es.i dent. Inspector*** c/o u~. s~ NRC Palisades Plant Route 2~ P. o. Box 155 Covert, Michigan 49043

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I CONSUMERS POWER COMPANY PALISADES, OOCKET NO. 5():2~5 SYSTEMATIC EVALUATION PROGRAM BRANCH COMPONENT INTEGRITY SECTION '

  • SAFETY EVALUATION REPORT SEP TOPIC III-10~B - PUMP FLYWHEEL INTEGRITY I.

Introduction The safety objective of this review is to assure that the integrity of the. primary reactor coolant pump flywheel is maintained thus preventing failures at normal operating speeds and speeds th~t might be. reached under accident conditions thereby precluding the generation of missiles. I I. Review Criteria The basis for the review is outlined in St~ndaid Review Plan (SRP)* S~ction 5.4.l.l and the Regulatory Guide 1.14, which describes and recorrmends a method acceptable to the NRC staff of implementing General Design Criterion 4, "Environmental arid Missile Design Bases 11 of Appendix A of 10 CFR 50; with regard to minimizing the. potential for failures of the flywheels of* the reactor coolant pumps. II I. Related Safety Topi cs and Interfaces* Internally generated missiles protection i_s evaluated under* SEP TopiclII-4.C

  • IV.

Review Guidelines There are two parts. to the reco1T1Tiendations of Regulatory Guide 1.14. The first part is related to the evaluation of materials of construction, design, fabrication, proof testing and pre-service inspection of the pump flywheels. The second part is concerned with the evaluation of the; procedures used for the inservice inspection of pump flywheels. V. Evaluation A. Material and Fabrication The flywheels for each pump are.divided into* three sections, two above .the rotor spider, and one below. **The two upper flywheels are bolted.. together and the upper flywheel (72" diameter) is keyed*-tothe lower (52" diameter) one by means.of an offset. At operating,~peed (900 rpm at Palisades) the bore stress d.ue to rotation. is /_73_0~ psi and 4100 psi. is due to. shrink fit. The operating temperature of the Palisades flywheels, which are enclosed by motor stator coils, will be above 1 oo°F. ~ ~ '.)

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.,_;,.... ___..... -:.;....;..-*.. ~-**=*-****-~t.... :-:.~:.-*~=~;:;.._,:__*.tf!'...:*.:..:*-.-*:-* ~. .. The disc material is SAE 1017. type 1020. which is equivalent to ASTM A 108 (1017), low carbon steel with a minium yfeld strength of 2~000

  • psi and tensile strength.of 50,000 psi. The pump flywheels are

. machined from cross rolled blanks. Regulatory* Guide* requires that the nil-ductility transition temperature (NOT) for the flywheel material be no higher than 10°F, that the Charpy

  • V-notch (CVN) upper shelf energy should be at least SO ft-lb., and that at normal operating temperature the material should have a dynamic stress intensity factor of at least 100 ksi,/lri.

This later require**:* ment can be satisfied by demonstrating that the material has a CVN

  • energy 1 evel of SO ft-1 b. at normal operating temperature..

Based on our* review we have determined that the NOT of the flywheel material at Palisades is no more than 40°F and an average CVN energy of 100 ft-lb. at 70°F. Based on these data we conclud~ that the NOT. requirement of Regulatory Guide 1.14 has not been met while the CVN and fracture toughness requirement have been met. Based on this infor-mation we conclude that the flywheels have adequate fracture toughness. Our conclusion is based on the following: Although the NOT is 40°F rather than l0°F, the operating* temperature of lQOOF is still GOOF above NOT. This margin. above NOT' coupled with a CVN energy at 70°F that far exceeds the 50 ft-los. required by the Regulatory Guide ensures that brittle fracture is unlikely and that a large tolerance to flaw-induced fracture exists. This flaw tolerance and operation in a tempera-ture* region where the potential for brittle frac.ture is reduced meets

  • the intent of Regulatory Guide 1 *. 14 although one specific requirement of the guide, has not been met.

B. Desi gri. We have evaluated the pump flywheels at Palisades* to compare* the ductile strength levels and.the fracture toughness at Palisades with the require-ments of Regulatory Guide 1.14~ "Reactor Coolant Pump Flywheel Integri*ty. u Regulatory Guide 1.14 requires that the ~argin against ductile rupture at normal operating speed and design overspeed be 3 and 1.5, respectively, compared to the minimum ~pectfied yield strength. For the.flywheels at. Palisades the margins against ductile rupture at normal operating speed is 3.07 and 2.0 at a design overspeed of 12S%,. Therefore the.margin *.* at non:nal :operating speed is 2% more than that r*equired by the Regulatory* Guide while the margin at design overspeed exceeds the required margin by 30%. Hence, the* margins against ductile fracture required by.Regulatory Guide 1.14 have been met. ~--*--*-... *--*-~-----* -----*-----*-*-----* --.~* I

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  • Inservice Inspection Program The Palisades plant has three flywheels that are made of SAE 1017, Type 1020~ low carbon steel with a minimum yield strength of 27,000 psi. Other flywheels we.have reviewed recently were made"'of higher quality materials, either A533B or A516, Gr65 with yield strength of 50,000 and 65,000 psi respectively.

Two of the flywheels have a dia-meter of about 52 inches and are located within the stator windings of the motor. The third, and_uppermo,st flywheel has a* diameter of 72 inches and is located within the motor housing but above the windings of the motor. Unlike previously reviewed designs,. the Palisades fly-wheels. are shrink fitted to the motor.shaft. The staff concluded in the presentat_ion of the safety aspects of the Palisades plant to the ACRS committee on November 18, 1969 that no additional protection against the effects of missiles from the small flywheels need be required because the pump speed being only 900-rpm and the. stator windings of the motor and the motor housing have the. capacity to absorb.t~e kinetic energy of the missile. \\ However, in view of the use of material of lower toughness than provided* in other designs, the ACRS recorrmended the following inspection program;

1.

100% UT baseline inspection of the upper 72-inch flywheels, including. the. disc~shaft interface.

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  • 100% UT inservice inspection of the tipper 72-inch flywheel including. *
  • the disc-shaft interface, at each refueling shutdown.

(about every 19 months.)

3. A visual inspection, to the* extent practical, using optical means to provide interior access where required. of all three flywheels in each motor each time UT tnspections of the upper flywheels are performed.

Regulatory Guide 1.14 as well 'as the ASME Code Section XI requires the following inservice inspection program for each flywheel: 1 *. An in place ultra*sonic volumetric examination of the-areas of higher'

  • stress concentration at the bore and keyw~y *at approximately three-year interva 1 s.
2.

A surface examination of all exposed surfaces and complete ultrasonic volumetric examination* at approximately JO year ;*ntervals,.

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' In 1 ieu of the requirements of Regulatory Guide l ~ 14, UT examination of the areas of higher stress concentration at three-year intervals and complete volumetric examination at ten-year intervals, the staff imposed the requirement of 100% volumetric inspection of the upper flywheel at . each refueling which occur.s approximately every 18 months. In accordance with the Palisades Plant Tech~icaf Specifications 4.3 and 4.12, inservice inspection no, 6 was conducted during the period September 8, 1979* to May 28, 1980. No deterioration has been found in . the upper pump flywheel. The analysis performed by Combustion Engineering shows that a 3~5" through crack will be required to cause failure at 125% overspeed at lower temperature and not extrapolated to operating temperature. The experience of motor flyWheel combinations similar in design to* Palisades units has been very favorable. No flywheel failure, er other associated flywheel problem, has* ever been experienced with this type design. We recommend that the Palisades plant continue performing 100% volumetric. inspection of the. upper flywheel at each refueling and in addition should include a visual inspection of other.two flywheels* whenever a pump motor overhauling is required.~ VI~ Conclusions. l . ~ I '.:i

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. ! l' We. have. reviewed the materials, fabrication,. design and inspection aspects of the pump flywheels at Palisades for compliance with Regulatory Guide 1.14. Based on our review we.. conclude that the requirements for fabrication and the margins against flaw induced fracture.and yielding required by Regulatory Guide* 1.14 have been satisfied. for the flywheels.* The present inservice inspection of the upper flywheel is more stringent than Regulatory Guide. 1.14. However, the other two flywheels (52") are not inspected at present, hence a visual inspection during a* pump motor overhaul will be reassuring. ... **~** - - - -*.*- -

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