ML18065A434

Application for Amend to License DPR-20,revising TS Re Primary Coolant Pump Flywheel Insp.Rev 1 to Structural Integrity Assoc,Inc Rept SIR-94-080, Relaxation of Reactor Coolant Pump Flywheel Insp Requirements Encl

ML18065A434
Person / Time
Site:	Palisades
Issue date:	01/18/1996
From:	Smedley R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18065A435	List: ML18065A434 ML18065A436
References
NUDOCS 9601250074
Download: ML18065A434 (8)

Text

POWERiNii MICHlliAN"S PROGRESS Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 January 18, 1996 U S Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT TECHNICAL SPECIFICATIONS CHANGE REQUEST - PRIMARY COOLANT PUMP FLYWHEEL INSPECTIONS A change to the Palisades Technical Specifications is requested. This change is desired to allow the deletion of inservice inspections (ISi) of primary coolant pump flywheels. This Technical Specification Change Request (TSCR) is provided as Attachment 1.

Attachment 2 to this submittal contains the proposed Technical Specification and basis document pages and Attachment 3 contains the existing Technical Specification and basis document pages marked up to show the proposed changes.

Palisades is submitting this change in conjunction with the Combustion Engineeering Owners Group (CEOG) since this change has been determined to be generic to all CE pressurized water reactors with commitments for ISi of primary coolant pump flywheels. Attachment 4 is the CEOG report entitled "Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements", which has been prepared for seven Combustion Engineering nuclear units, including Palisades. This report provides the justification for eliminating the ISi of primary coolant pump flywheels at these units.

This tSCR is being submitted under the Cost Beneficial Licensing Action (CBLA) program described in NRC Administrative Letter 95-02 dated February 23, 1995. The

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PDR ADOCK 05000255 P PDR A~~COll/IPANY

• 2 justification for this request is contained in Attachment 5. Palisades requests the effective date for the Technical Specification Change to be no later than August 1, 1996 in order to achieve the maximum cost benefit by allowing deletion of the flywheel examinations during the 1996 refueling outage. This refueling outage is currently scheduled to begin on November 2, 1996.

SUMMARY

OF COMMITMENTS This letter contains no new commitments and no revisions to existing commitments.

Richard W Smedley Manager, Licensing CC Administrator, Region Ill, USNRC Project Manager, NRR, USNRC NRC Resident Inspector - Palisades 5 Attachments

CONSUMERS POWER COMPANY To the best of my knowledge, the contents of this document entitled "Technical Specification Change Request - Primary Coolant Pump Flywheel Inspections" are truthful and compl~te.

By Qw~Q ~

R-ic_h_a~rd~W~S_m_e_d-le-y~~~~~~~~~~ -

Manager, Licensing sworn and subscribed to before me this /?

4.

day of N 1996.

~r;.0~

Alora M Davis, Notary Public Berrien County, Michigan (Acting in Van Buren County, Michigan)

My commission expires August 26, 1999

[SEAL]

ATTACHMENT 1 CONSUMERS POWER COMPANY PALISADES PLANT DOCKET 50-255

• TECHNICAL SPECIFICATION CHANGE REQUEST - SECTION 4.3 LICENSE DPR-20 PRIMARY COOLANT PUMP FLYWHEEL INSPECTIONS

• 4 Pages

• • CONSUMERS POWER COMPANY Docket 50-255 Request for Change to the Technical Specifications License DPR-20 It is requested that the Technical Specifications contained in the Facility Operating License DPR-20, Docket 50-255, issued to Consumers Power Company on February 21, 1991, for the Palisades Plant be changed as described below:

I. DESCRIPTION OF PROPOSED CHANGES This TSCR proposes that Technical Specification (TS) Section 4.3 and Table 4.3.2, item 2 concerning periodic inservice inspection (ISi) of primary coolant pump (PCP) flywheels be revised. The proposed changes delete the requirement to conduct a volumetric examination of the upper PCP flywheels during each refueling outage.

The basis statement for TS 4.3 does not require modification since it does not presently cover the flywheel examination.

11. REASONS FOR CHANGE

• Background The flywheels on primary coolant pump motors provide rotational inertia to prolong pump coastdown in the event pump power is lost, thus ensuring a more gradual decay of primary coolant flow to the core.

General Design Criteria 4, "Environmental and Dynamic Effects Design Bases,"

of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50 requires nuclear power plant structures, systems, and components important to safety be protected against the effects of missiles that might result from equipment failures. PCP flywheels could degrade and produ.ce high energy missiles at both normal operating and overspeed conditions (e.g.,

during a loss of coolant accident). In RG 1.14, Rev. 1, entitled "Reactor Coolant Pump Flywheel Integrity," the NRC provides recommendations for material fabrication, design, and preservice and inservice inspection for PCP flywheels which, if followed, reduce the probability of flywheel failure sufficiently so that special protective features (e.g. missile shields) are not required. The ISi recommendations in RG 1.14 are identified in Section 5.4.1.1 of the Standard Review Plan as providing an acceptable inspection program. The TSs of many licensees include a requirement to provide ISi of PCP flywheels in accordance with the recommendations of RG 1.14 or other methods acceptable to the Staff.

• Discussion of Change The Combustion Engineering Owners Group (CEOG) contracted with Structural Integrity Associates, Inc. to develop the report (Attachment 4) which provides 2

justification that flywheel integrity can be assured without the requirement to conduct ISi. Consumers Power Company, Entergy Operations, Florida Power

& Light, and Northeast Utilities Service Company .participated in this project.

The report reviews previous ISi results, evaluates potential degradation mechanisms, and provides stress analyses and fracture mechanics evaluations of flywheels.

The report justifies the elimination of the periodic inspection for PCP flywheels, as described in Regulatory Guide 1.14, Rev 1, on a generic basis for the plants studied, including Palisades. The results which are specific to Palisades are summarized as follows:

1. _The material specification for the Palisades flywheel was determined to be A 108 material based on correspondence from the NRC on May 15, 1981 (DMCrutchfield to DPHoffman on Pump Flywheel Integrity) .

. Further verification of this material specification could not be located .

• • 2. No service induced flaws have ever been identified in any of the Palisades PCP flywheels (or any other plant studied). Fatigue was found to be the only potentially significant degradation mechanism for the low alloy steel PCP flywheels in pressurized water reactors.

3. The allowable flaw size is determined by considering the maximum centrifugal stress at accident speed and shrink-fit stresses at zero speed. The smaller allowable flaw size for these two stresses is the allowable flaw size for the flywheel. For Palisades, the maximum allowable flaw size for the flywheels is > 2.00 inches, corresponding fo an accident speed of 150% of normal operating speed.

4. Since fatigue is the only degradation mechanism which will result in propagation of existing cracks in the flywheel, a fatigue crack growth evaluation was done to determine the growth of pre-existing cracks. An initial flaw size of 0.25 inches is assumed based upon a conservative detection threshold for ultrasonic examination (UT). The design number of startup/shutdown cycles for a PCP motor is no more than 500 for plant life. However, for this evaluation, 4000 cycles were considered to determine crack growth. Using minimum material properties, accident speed stresses, and a conservative number of cycles, a preexisting 0.25

• inch crack would grow to 0.2515 inches in a Palisades flywheel. This value is well below the allowable flaw size of> 2.00 inches calculated

• for Palisades at 150% of normal operating speed.

Based upon the calculations contained in the report, it can be determined that a preservice flaw of 0.25 inches would not grow to the allowable flaw size in a 3

plant's licensed life, or even during life extension. Therefore, inservice inspections of PCP flywheels have a marginal contribution to safety and can be eliminated,' thus allowing resources to be used for items of greater safety significance and permitting a reduction in personnel radiation exposure.

Ill. DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION Consumers Power Company finds the activities associated with this proposed Technical Specifications change involve no signifcant hazards. Therefore a no significant hazards determination per 10 CFR Part 50.92(c) is justified.

The following evaluation supports the finding that operation of the facility in accordance with the proposed change to the Technical Specifications would not:

1. Involve a significant increase in the probability or consequences of an

• accident previously evaluated .

The proposed change to the Technical Specifications would delete the requirement to perform non-destructive examination of the upper flywheel on the PCPs. The fracture mechanics analyses conducted to support the change show that a preexisting crack sized just below detection level will not grow to the flaw size necessary to result in flywheel failure within the life of the plant. This analysis conservatively assumes minimum material properties, maximum flywheel accident speed, location of the flaw in the highest stress area and a number of startup/ shutdown cycles eight times greater than expected. Since an existing flaw in the flywheel will not grow to the allowable flaw size under normal operating conditions or to the critical flaw size under LOCA conditions over-the life of the plant, elimination of inservice inspection for such cracks during the plant's life will not involve a significant increase in the probability of an accident previously considered.

The proposed changes do not increase the amount of radioactive material available for release or modify any systems used for mitigation of such releases during accident conditions. Therefore, operation of the facility in accordance with the proposed change to the Technical

• Specifications would not involve a significant increase in the probability or consequences of an accident previously evaluated.

• 2. Create the possibility of a new or different kind of accident from any previously evaluated.

The proposed change to the Technical Specifications would not change 4

the design, configuration, or method of operation of the plant and therefore, operation of the facility in accordance with the proposed

. change to the Technical Specifications would not create the possibility of a new or different kind of accident from any previously evaluated:

3. Involve a significant reduction in a margin of safety.

The proposed change to the Technical Specifications would not result in a significant reduction in the margin of safety. Significant conservatisms have been. used for calculating the allowable flaw size, critical flaw size and crack growth rate in the PCP flywheels.' These include minimum material properties, maximum flywheel accident speed, location of the postulated flaw in highest stress area and a number of startup/shutdown cycles eight times greater than expected. Since an existing flaw in the flywheel will not grow to the maximum allowable flaw size under normal operating conditions or to the critical flaw size under LOCA conditions over the life of the plant, elimination of inservice inspections for such cracks during the plant's life will not involve a significant reduction in the margin of safety.

IV. Conclusion Based upon the reasoning presented above and the previous discussion of the amendment request, Palisades has determined that the requested change does not involve a significant hazards consideration. The Palisades Plant Review Committee has reviewed this Technical Specifications Change Request and has determined that proposing this change does not involve an unreviewed safety question. Further, the change has been reviewed by the Nuclear Performance Assessment Department.