ML20135D841
| ML20135D841 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 12/03/1996 |
| From: | Muench R WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20135D844 | List: |
| References | |
| ET-96-0097, ET-96-97, NUDOCS 9612100195 | |
| Download: ML20135D841 (13) | |
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i W$LF CREEK NUCLEAR OPERATING CORPORATION Richard A. Muench Vice President Engineering j
t December 3, 1996 ET 96-0097 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-137 Washington, D.
C.
20555
Subject:
Docket No. 50-482:
Revision to Technical Specification 6.8.5b, Reactor Coolant Pump Flywheel Inspection Program Gentlemen:
The following is an application for amendment to Facility Operating License No.
NPF-42 for Wolf Creek Generating Station.
This request proposes to revise Technical Specification 6.8.5b, Reactor Coolant Pump Flywheel Inspection Program to provide an exception to the examination requirements in Regulatory Guide 1.14, Revision 1,
" Reactor Coolant Pump Flywheel Integrity."
The proposed exception to the recommendations of Regulatory Position C.4.b would allow for an acceptable inspection method of either an ultrasonic volumetric or surface examination.
The acceptable inspection method would be conducted at approximately 10 year intervals.
Wolf Creek Nuclear Operating Corporation's (WCNOC) request is based on the results of previous examinations and the NRC Safety Evaluation Report on WCAP-14535, " Topical Report on Reactor Coolant Pump Flywheel Inspection Elimination."
Additionally, this license amendment request corrects a typographical error in Technical Specification 6.8.5c, Containment Tendon Surveillance Program.
This specification incorrectly references draft Revision 3 of Regulatory Guide.l.35, dated April, 1989.
Draft Revision 3 of Regulatory Guide 1.35 was issued in April, 1979.
A Safety Evaluation is provided in Attachment I, and Attachment II provides a No Significant Hazards Consideration Determination.
Attachment III is the Environmental Impact Determination, and the marked-up technical specification
\\k page for this request is provided in Attachment IV.
A00) 9612100195 961203 PDR ADOCK 05000482 p
PD P.O Box 411/ Burhngton, KS 66839 / Phone: (316) 364-8831 An Equal Opportunny Employer M F'HCVET
ET 96-0097 Page 2 of 2 In accordance with 10 CFR 50.91, a copy of this revision to our original application, with attachments, is being provided to the designated Kansas State official.
This proposed revision to the WCGS Technical Specifications will be fully implemented within 30 days of formal NRC approval.
If you have any questions concerning this matter,. please contact me at (316) 364-8831, extension 4034, or Mr. Terry S. Morrill, at extension 8707.
Very truly yours, h44 Richard A. Muench RAM /jad Attachments I
- Safety Evaluation II - No Significant Hazards Consideration Determination III - Environmental Impact Determination IV - Proposed Technical Specification Ch,ange cc:
V.
L.
Cooper (KDHE), w/a L.
J.
Callan (NRC), w/a W.
D. Johnson (NRC), w/a J.
F. Ringwald (NRC), w/a J.
C. Stone (NRC), w/a
t, STATE OF KANSAS
)
P
)
SS j
COUNTY OF COFFEY
)
l Richard'A. Muench, of lawful age,.being first duly sworn upon. cath says'that I
he is Vice President Engineering of Wolf Creek Nuclear Operating Corporation;
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that he has read the foregoing document ~and knows the content thereof; -that J
he has executed that same foreand on behalf of said Corporation with full
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. power and authority to do so;.and that the facts therein stated are true and i
correct to the best of his knowledge, information and' belief.
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l 1
\\
r By
//fAAA Richard A. Muench J
Vice President Engineering 1
SUBSCRIBED and sworn to before me this 3
day of b.r_c.
i 1996.
nal Ld:% rerf ANGELA E.WESSEL Notary Pubgic
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Ig Notary Publie State of Kansas A Appt. Expires 0 7/03/99 J
l Expiration Date No 1 a_ 6 /997
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Atte. chm nt I to ET 96-0097 Pr.g3 'l of 5 t
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4 ATTACIDutNT I J
SAFETY EVALUATION 4
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. Atta,chmsnt I to ET 96-0097
- Page'2 of 5 Safety Evaluation Proposed t% nga This license amendment request proposes to revise the Wolf Creek Generating Station (WCGS) Technical Specification 6.8.5b, Reactor Coolant Pump Flywheel Inspection Program to provide an exception to the examination requirements in Regulatory Guide 1.14, Revision 1,
" Reactor Coolant Pump Flywheel Integrity."
The proposed exception to the recommendations of Regulatory Position C.4.b would allow for an acceptable inspection method of either an ultrasonic
. volumetric or surface examination.
The acceptable inspection method would be conducted at approximately 10-year intervals.
This license amendment request additionally correcL4, a typographical error in Technical Specification 6.8.5c, Containment Tendon Surveillance Program. This specification incorrectly references draft Revision 3 of Regulatory Guide l
1.35, dated April, 1989.
Draft Revision 3 of Regulatory Guide 1.35 was issued in April, 1979.
WCNOC submitted a license emendment request on May 24, 1994 (NA 94-0089) and a supplemental letter on April 6, 1995 (CO 95-0032) which proposed to incorporate improvements in scope and content endorsed by the NRC in its Final Policy Statement on Technical Specifications for Improvements for Nuclear Power Reactors. As a result of this request, specification 6.8.5c was proposed with an incorrect issuance date of the draft Regulatory Guide.
The Updated Safety Analysis Report, Appendix 3A, correctly references draft Revision 3 of Regulatory Guide 1.35, dated April 1979.
Background
Regulatory Guide 1.14, Revision 1, Regulatory Position C.4.b states " Inservice inspection should be performed for each flywheel as follows: (2) A surface examination of all exposed surfaces and complete ultrasonic volumetric examination at approximately 10-year intervals, during the plant shutdown j
coinciding with the inservice inspection schedule as required by Section XI of i
the ASME Code."
In February 1995, a change to the Updated Safetr W1ysis Report (USAR) was implemented to add an exception to the comm-.tmen % to Regulatory Guide 1.14, Revision 1,
to address the frequency of the. flyv neel inspection.
Because of a change to the 10-year reactor coolant pump (RCP) motor refurbishment schedule, examination of the flywheel in the RCP "D" motor was not performed prior to the completion of the 10-year in arvice inspection interval, including the extension allowed by ASME Section %I.
Subsequently, during an NRC inspection conducted during the period Octobel 1996 through October 25, 1996, the NRC indicated that the proposed exception should have been reviewed and approved by the NRC as a change to the Technical Specifications.
Evaluation An integral part of the reactor coolant system (RCS) fa pressurized water j
reactor plants is the
- RCP, a vertical, single stage, single-suction, j
centrifugal, shaft seal pump.
The RCP ensures an adequate cooling flow rate 4
by circulating large volumes of the primary coolant water at high temperature i
and pressure through the RCS.
Following an assumed loss of power to the RCP I
motor, the flywheel, in conjunction with the impeller and motor assembly, i
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Attachment I to ET 96-0097 4
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provide sufficient rotational inertia to assure adequate cooling flow during
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RCP coastdown.
This forced flow and the subsequent natural circulation effect of the RCS results in adequate core cSoling.
l During normal power operation, the RCP flywheel possesses sufficient kinetic energy - to produce high energy r 'ssiles in the event of fai3 ure.
Conditions l
which may result in overspeed of the RCP increases both the potential for i
failure and the kinetic energy of the flywheel.
This led to issuance of I
Regulatory Guide.1.14 which provided recommendations of actions to ensure flywheel integrity.
Integrity of the RCP flywheel is assured on the basis of the use of suitable
- material, adequate design and inspection.
The calculated stresses at operating speed are based on stresses due to centrifugal forces.
The stress resulting from the interference fit of the flywheel on the shaft is less than 2,000 psi at zero speed, but this stress becomes zero at approximately 600 rpm because of. radial expansion of the hub.
The RCPs run at approximately 1,190 rpm and may operate briefly at overspeeds of 109 percent during loss of load.
For conservatism, however, 125 percent of operating speed was selected as the design speed for the pumps. The flywheels were given a preoperational test of 125 percent of the maximum synchronous speed of the motor.
The flywheel consists of two thick plates bolted together.
The flywheel material is produced by a process that minimizes flaws in the material and improves its fracture toughness properties, such as vacuum degassing, vacuum melting, or electroslag remelting.
Each plate is f2bricated from SA-533, Grade B, Class 1 steel.
Previous Examination Results RCP flywheel examinations are performed in accordance with the WCGS Inservice Inspection Program during refueling outages or motor refurbishment.
The results of full volumetric examinations and complete surface examinations, including bore and keyway areas performed by WCNOC during the first inservice inspection interval (see Table 1) met the recommendations of the Regulatory Guide.
Additionally, the in-place volumetric examinations of the RCP flywheels at approximately 3-year intervals were performed with no recordable indications detected.
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WCNOC shares a spare RCP motor with Union Electric's Callaway Plant. This j
allows RCP motor refurbishment to be performed with each motor transported j
offsite.
WCNOC performs the required 10-year inservice inspections during l
this refurbiehment because accessibility for flywheel inspection is better and j
the work environment is improved, e.g.,
not restricted to examination within J
the bis ield or other locations within the containment structure.
RCP motor "D"
is not represented in Table 1 because the 10-year inservice inspection was not performed as a result of changes to the RCP refurbishment schedule. Although the 10-year examination had not been performed as required by Regulatory Guide 1.14, the 3-year examination was successfully completed as scheduled with no indications identified.
This 3-year examination has been determined to be an acceptable alternative to the 10-year examination requirements through issuance of a NRC Safety Evaluation Report (SER) (letter
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Attachment I to ET 96-0097
' Page 4 of 5 dated September 12, 1996) on WCAP-14 53 5,
- Topical Report on Reactor Coolant Pump Flywheel Inspection Elimination."
The focus of the WCAP was to eliminate examinations of the flywheels altogether; however, it was accepted by the NRC that the requirements could be reduced based on the evidence provided by the WCAP.
As will be further i
discussed, licensees may now perform an ultrasonic examination of higher stress regions, similar to what is performed by WCNOC on the approximate 3-year frequency, or a complete surface examination on an approximate 10-year frequency in lieu of the current examination schedule established by Regulatory Guide 1.14, Revision 1.
Based on the evaluation provided by the NRC SER, the 3-year examination on RCP motor "D"
performed in September 1994 provides an acceptable examination to satisfy the 10-year inservice inspection requirements.
Table 1 Full 10-Year Surface and Volumetric Examinations T
Year RCP ID Examination Results Complete MT (PT of bore / keyway) i 1991 B
and UT of high stress regions No indications and O' UT of full volume.
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Complete MT (PT of bore / keyway)
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1994 C
and UT of high stress regions No indications i
and O' UT of full volume.
j Complete MT (PT of bore / keyway)
Circular spacer wear 1995 A
and UT of high stress regions marks on bottom surface and 0* UT of full volume.
within area of seal ring.
- Topical Report on Reactor Coolant Pump Flywheel Inspection Elimination" WCAP-14535 documents the results of flywheel inspections from approximately 57 nuclear stations covering approximately 217 flywheels and 729 examinations.
The results show that there were no indications found that would affect the integrity of the flywheels.
A number of recordable indications found were in the form of nicks and gashes in the keyway area created as a result of the disassembly and subsequent reassembly required to perform the flywheel inspections.
1 The results of flywheel inspections presented in WCAP-14535 show that flywheel integrity and plant safety are increased by eliminating flywheel inspections.
Detailed stress and fracture analyses as well as risk analysis have been completed with the results indicating that there would be no change in the probability of failure for RCP flywheels if all inspections were eliminated.
The NRC documented in their SER (letter dated September 12, 1996) to Duquesne Light Company that it was acceptable to reference WCAP-14535 in license applications to the extent specified and under the limitation delineated in the report and the associated NR.C SER.
The SER concluded that inspections should not be completely eliminated and should be conducted during scheduled inservice inspections or RCP motor maintenance at approximately 10-year
Attachment I to ET 95-0097
- Page'5 of 5 intervals.
WCNOC has confirmed that the flywheels are made of SA-533 B i
material (as discussed above)and that the items specified for accepting this amendment request in the conclusions section of the SER are met.
The SER for WCAP-14535 defined the volume for the alternate ultrasonic examination.
The volume was defined from the inner bore of the flywheel to the circle of one-half the outer radius.
Information as to why this is the defined volume is not clear in the SER and was not included within the WCAP I
since the WCAP focused on complete elimination.
This was also the situation with implementation of the 3-year examination requirements of Regulatory Guide 1.14. This amendment defines the volume to coincide with the radial distance provided by the flywheel gage holes.
The gage holes provide access for inspection of the higher stress regions near the inner bore and keyways without completely removing the motor shroud.
The volume is being defined as such since these gage holes do not represent the same radial distance as one-half the outer bore but is sufficient to ultrasonically examine the higher stress regions of importance.
Based on the above discussions and the no significant hazards consideration
~ determination presented in Attachment II, the proposed changes do not increase the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated. in the safety analysis report; or create a possibility for an accident or malfunction j
of a different type than any previously evaluated in the safety analysis i
report; or reduce the margin of safety as defined in the basis for any technical specification.
Therefore, the proposed changes do not adversely affect or endanger the health or safety of the general public or involve a significant safety hazard.
Attachm:nt II to ET 95-0097
' Page 1 of 3 1
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i ATTACHMENT II NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION i
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. Attachment II to ET 96-0097
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No significant Hazards Consideration Determination 1
i This license amendment request proposes to revise the Wolf Creek Generating I
Station (WCGS) Technical Specification 6.8.5b, Reactor Coolant Pump Flywheel Inspection Program to provide an exception to the examination requirements in Regulatory Guide 1.14, Revision 1,
" Reactor Coolant Pump Flywheel Integrity."
l The proposed exception to the recommendations of Regulatory Position C.4.b l
would allow for an acceptable inspection method of either an ultrasonic l
)
volumetric or surface examination.
The acceptable inspection method would be l
conducted at approximately 10 year intervals.
Additionally, this license amendment request additionally corrects a
typographical error in Technical Specification 6.8.5c, containment Tendon j
Surveillance Program.
This specification incorrectly references draft i
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Revision 3 of Regulatory Guide 1.35, dated' April, 1989.
Draft Revision 3 of j
Regulatory Guide 1.35 was issued in April, 1979.
WCNOC submitted a license j
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amendment request on May 24, 1994(NA 94-0089) and a supplemental letter on April 6, 1995 (CO 95-0032) which proposed to incorporate improvements in scope
{
and content endorsed by the NRC in its Final Policy Statement on Technical i
Specifications for Improvements for Nuclear Power Reactors.
As a result of l
this request, specification 6.8.5c was proposed with an incorrect issuance date of the draft Regulatory Guide.
The Updated Safety Analysis Report, Appendix 3A, correctly references draft Revision 3 of Regulatory Guide 1.35, dated April 1979.
The NRC has provided standards for determining whether a significant hazards j
consideration exists (10 CFR 50. 92 (c) ).
A proposed amendment to an operating l
license for a facility involves no significant hazards consideration, if j
operation of the facility in accordance with the proposed amendments would not
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(1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or j
different kind of accident from any accident previously evaluated; or (3) i involve a significant reduction in a margin of safety.
Each standard is j
discussed below:
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Standard I - Involve a
Significant Increase in the Probability or i-Consequences of an Accident Previously Evaluated The safety function of the RCP flywheels is to provide a coastdown period during which the RCPs would continue to provide reactor coolant flow to the reactor after loss of power to the RCPs.
The maximum loading on the RCP flywheel results from overspeed following a LOCA.
The maximum obtainable speed in the event of a LOCA was predicted to be less than 1500 rpm.
Therefore, a peak LOCA speed of 1500 rpm is used in the evaluation of RCP flywheel integrity in WCAP-14$35.
This integrity evaluation shows a very high flaw tolerance for the flywheels.
The proposed change does not affect that evaluation.
Reduced coastdown times due to a single failed flywheel is bounded by the locked rotor analysis, therefore, it would not place the plant in an unanalyzed condition.
Therefore, these changes do not involve a significant increase in the probability or consequences of an accident l
previously evaluated.
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Attachment II to ET 96-0097 Paga 3 of 3 Standard II - Create the Possibility of a New or Different Kind of Accident from any Previously Evaluated The proposed amendment does not create the possibility of a new or different kind of accident from any previously evaluated since the proposed amendments will not change the physical plant or the modes of plant operation defined in the. facility operating license.
No new failure mode is introduced due to the proposed change, since the proposed change does not involve the addition or modification of equipment, nor do they alter the design or operation of affected plant systems, structures, or components.
Standard III - Involve a Significant Reduction in the Margin of Safety The operating limits and functional capabilities of the affected systems, structures, and components are basically unchanged by the proposed amendment.
The results of the flywheel inspections performed have identified no indications affecting flywheel integrity.
As identified in WCAP-14535, detailed stress analysis as well as risk analysis have been completed with the results indicating that there would be no change in the probability of failure for RCP flywheels if all inspections were eliminated.
Therefore these changes do not involve a significant reduction in the margin of safety.
Based on the above discussions, it has been determined that the requested technical ; specification revision does not involve a significant increase in the probability or consequences of an accident or other adverse condition over previous evaluations; or create the possibility of a new or different kind of accident or condition over previous evaluations; or involve a significant reduction in a margin of safety.
The requested license amendment does not i
involve a significant hazards consideration.
i Attachm:nt III to ET 96-0097 Paga'1 of 2 1
i ATTACHMENT III ENVIRONMENTAL IMPACT DETERMINATION 1
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Attachment III to ET 96-0097 i
page'2 of 2 Environmental Impact Determination 4
I 10 CFR 51. 22 (b) specifies the criteria for categorical exclusions from the i
requirement for a specific environmental assessment per 10 CFR 51.21.
This
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amendment request meets the criteria specified in 10 CFR
- 51. 22 (c) (9) as specified below:
J (i) the amendment involves no significant hazards consideration As demonstrated in Attachment II, the proposed changes do not involve any
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significant hazards consideration.
(ii) there is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite i
The proposed changes do nct involve a change to the facility or operating procedures that would cause an increase in the amounts of effluents or create new types of effluents.
(iii) there is no significant increase in individual or cumulative I
occupational radiation exposure The proposed changes do not create additional exposure to personnel nor affect levels of radiation present.
Also, the proposed change does not result in any I
increase in individual or cumulative occupational radiation exposure.
Based on the above it is concluded that there will be no impact on the j
environment resulting from this change and the change meets the criteria i
specified in 10 CFR 51.22 for a categorical exclusion from the requirements of I
10 CFR 51.21 relative to requiring a specific environmental assessment by the Commission.
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