ML17122A140
| ML17122A140 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 05/10/2017 |
| From: | Benjamin Beasley Plant Licensing Branch II |
| To: | Nazar M Florida Power & Light Co |
| Marshall M | |
| References | |
| CAC MF9459 | |
| Download: ML17122A140 (12) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Mano Nazar President and Chief Nuclear Officer Nuclear Division Florida Power & Light Company Mail Stop EX/JB 700 Universe Blvd.
Juno Beach, FL 33408 May 10, 2017
SUBJECT:
TURKEY POINT NUCLEAR GENERATING UNIT NO. 4-SAFETY EVALUATION FOR RELIEF REQUEST NO. 5 FOR FIFTH 10-YEAR INSERVICE INSPECTION INTERVAL (CAC NO. MF9459)
Dear Mr. Nazar:
By letter L-2017-050 dated March 22, 2017 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML17093A457), Florida Power & Light Company (the licensee) submitted Relief Request No. 5 for the fifth 10-year inservice inspection interval at Turkey Point Nuclear Generating Unit No. 4 (Turkey Point 4 ). Pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Paragraph 50.55a(z)(2), the licensee requested the U.S.
Nuclear Regulatory Commission (NRC) to authorize an alternative to the requirements of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 2007 Edition with Addenda through 2008, Subsubarticle IWC-3130, subparagraph IWC-3132.2 because compliance with the specified requirements would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety.
As documented in NRC memorandum from A. Klett to B. Beasley dated April 6, 2017 (ADAMS Accession No. ML17082A510), the NRC staff verbally authorized the use of the proposed alternative in Relief Request No. 5 for Turkey Point 4 for up to 90 days from March 22, 2017, which was the date of the staff's verbal authorization. The NRC staff determined that the proposed alternative was technically justified and provided reasonable assurance of the structural integrity of the affected piping. The enclosed safety evaluation documents the technical basis of the staff's verbal authorization, and the staff concludes that the licensee adequately addressed the regulatory requirements in 10 CFR 50.55a(z)(2).
All other requirements of 1 O CFR 50.55a and the ASME Code,Section XI for which relief was not specifically requested and approved in the subject request, remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.
If you have any questions regarding this issue, please contact the project manager, Mr. Michael Wentzel, at (301) 415-6459 or by e-mail at Michael.Wentzel@nrc.gov.
Docket No. 50-251
Enclosure:
Safety Evaluation cc w/encl.: Distribution via Listserv Sincerely, Benjamin G. Beasley, Chief Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST NO. 5 FIFTH 10-YEAR INSERVICE INSPECTION INTERVAL FLORIDA POWER & LIGHT COMPANY TURKEY POINT NUCLEAR GENERATING UNIT NO. 4 DOCKET NO. 50-251
1.0 INTRODUCTION
By letter L-2017-050 dated March 22, 2017, 1 Florida Power & Light Company (the licensee) submitted Relief Request No. 5 for the fifth 10-year inservice inspection interval at Turkey Point Nuclear Generating Unit No. 4 (Turkey Point 4 ). Pursuant to Title 10 of the Code of Federal Regulations (1 O CFR), Paragraph 50.55a(z)(2), the licensee requested the U.S. Nuclear Regulatory Commission (NRC) to authorize an alternative to the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (BPV) Code,Section XI, 2007 Edition with Addenda through 2008, Subsubarticle IWC-3130, subparagraph IWC-3132.2, because compliance with the specified requirements would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety. The licensee proposed to temporarily delay ASME Code repair/replacement activities for a flaw in the high head safety injection recirculation test line and use ASME Code Case N-513-3, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping,Section XI, Division 1," to demonstrate structural integrity and accept a flaw by analysis in a non-moderate energy system.
As documented in NRC memorandum from A. Klett to B. Beasley dated April 6, 2017,2 the staff verbally authorized the use of the proposed alternative in Relief Request No. 5 for Turkey Point 4 for up to 90 days from March 22, 2017, which was the date of the verbal authorization.
The NRC staff determined that the proposed alternative was technically justified and provided reasonable assurance of the structural integrity of the affected piping. This safety evaluation documents the technical basis of the staff's verbal authorization.
2.0 REGULATORY EVALUATION
Paragraph 50.55a(g)(4) of 10 CFR states, in part, that ASME Code Class 1, 2, and 3, components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI.
1 Agencywide Documents Access and Management System (ADAMS) Accession No. ML17093A457.
2 ADAMS Accession No. ML17082A510.
Enclosure Paragraph 50.55a(z)(2) of 10 CFR states that alternatives to the requirements of 10 CFR 50.55a(g) may be used, when authorized by the NRC, if the licensee demonstrates that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Based on these regulations, and subject to the following technical evaluation, the staff finds that regulatory authority exists for the licensee to request and the NRC to authorize the licensee's proposed alternative. Accordingly, the NRC staff reviewed and evaluated the licensee's request pursuant to 10 CFR 50.55a(z)(2).
3.0 TECHNICAL EVALUATION
3.1 Licensee's Proposed Alternative 3.1.1 Affected Components and Code of Record The component affected by the proposed alternative is the ASME Class 2, 3/4-inch nominal pipe size, schedule 80S pipe segment, which is part of line Sl-1501R and located on the high head safety injection pump recirculation test line. This piping segment is located downstream of high head safety injection test line drain valve 4-943G, and upstream of the high head safety injection recirculation and test return line check valve 4-87 4C to refueling water storage tank.
The pipe is made of stainless steel A-312, Type 316 material.
The code of record for the fifth 10-year inservice inspection interval is the 2007 Edition through 2008 Addenda of the ASME BPV Code,Section XI, subject to the limitations and modifications in 10 CFR 50.55a(b).
3.1.2 Applicable Code Requirements The ASME Code,Section XI, subparagraph IWC-3132.2, "Acceptance by Corrective Measures or Repair Replacement Activity," states that a component containing relevant conditions is acceptable for continued service if the relevant conditions are corrected by repair or replacement activity or by corrective measures to the extent necessary to meet the acceptance standards of Table IWC-3410-1. The ASME Code,Section XI, Code Case N-513-3, as conditioned by NRC Regulatory Guide 1.147, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1," Revision 17, dated August 2014, 3 states that provisions of this case apply to Class 2 or 3 piping whose maximum operating temperature does not exceed 200 degrees Fahrenheit (°F) and whose maximum operating pressure does not exceed 275 pounds per square inch gauge (psig). The ASME Code,Section XI, Non-mandatory Appendix C for flaw evaluation as specified in ASME Code Case N-513-3, Section 3, is restricted to 1-inch and greater nominal pipe size in other ASME Code references (e.g.,
IWC-3641 ). Section 2(h) of ASME Code Case N-513-3 requires the repair or replacement to occur no later than when the predicted flaw size exceeds the acceptance criteria, or the next scheduled outage, whichever occurs first. Regulatory Guide 1.147, Revision 17 also states that as a condition for using ASME Code Case N-513-3, the repair or replacement activities temporarily deferred under the provisions of the code case shall be performed during the next scheduled outage.
3 ADAMS Accession No. ML13339A689.
3.1.3 Reason for the Proposed Alternative On March 17, 2017, the licensee identified a through-wall leak on the subject 3/4-inch pipe with a leak rate of about 3 drops per minute. The location of the leak in the subject pipe was in a vertical run downstream of the high head safety injection test line drain valve 4-943G, and upstream of the high head safety injection minimum recirculation check valve, 4-874C, which is upstream of the Turkey Point 4 refueling water storage tank. The licensee stated that the flaw causing the leak is planar in nature based on it being observed as a combination of aligned pitting and cracks. The licensee sized the flaw by surface examination as being 0. 75 inches long and circumferentially oriented. The licensee did not observe other indications on the pipe.
The licensee performed an extent-of-condition inspection on five additional pipes for which similar operating conditions exist. The licensee stated that any additional discrepancies will be addressed under its corrective action program.
This pipe segment is in a test line connected to the normal recirculation line that is normally open to the refueling water storage tank and can be used by either Turkey Point 3 or 4. The leak is located in the normally stagnant leg of the test line, and it is only pressurized for normal plant operations when the high head safety injection pumps are tested or used to fill or test the safety injection accumulator tanks. When the emergency core cooling system is recirculating water from the containment sump during a design-basis accident, the refueling water storage tank is isolated, and the line can be pressurized to the high head safety injection pump discharge pressure.
The ASME Code repair or replacement of the pipe requires removal of the 4A and 48 high head safety injection pumps from service because the pipe is a pressure boundary of the shared minimum recirculation line. This activity is allowed to be performed and completed within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as allotted by Technical Specification (TS) 3.5.2, ACTION d with the 3A and 38 high head safety injection pumps operable, and Unit 3 is in MODES 1, 2 or 3. On March 18, 2017, the licensee entered TS 3.5.2, ACTION d and was preparing to commence the Code repair or replacement activities; however, Turkey Point 3 experienced a reactor trip with a loss of the 3A 4-kilovolt electrical bus and, therefore, a loss of the 3A high head safety injection pump.
Subsequent to the Turkey Point 3 reactor trip, the licensee restored the Turkey Point 4 high head safety injection pumps to service and exited TS 3.5.2, ACTION d.
At the time of the licensee's submittal, Turkey Point 4 was in MODE 1, and Turkey Point 3 was in MODE 5, and the licensee was preparing to commence the Cycle 29 refueling outage activities on Turkey Point 3. Under that plant configuration, TS Limiting Condition for Operation (LCO) 3.5.2.a requires that four high head safety injection pumps be operable during MODES 1 through 3, and has a footnote clarifying that if the opposite unit is in MODES 4, 5, or 6, then two high head safety injection pumps associated with the operating unit are required to be operable.
In its submittal, the licensee stated that in the current plant configuration, performing an immediate ASME Code repair or replacement activity to correct the subject flaw would result in exceeding the time requirements of the required action for TS LCO 3.5.2.a, which would require entry into TS 3.0.3 and the commencement of a Turkey Point 4 shutdown within an hour. As such, an immediate ASME Code repair or replacement activity would create a hardship based on the potential risks associated with a shutdown, the thermal stress cycling of plant components, and emergent equipment issues incurred during shutdown and startup evolutions, with no compensating increase in the level of quality and safety gained by immediate repair of the flaw. Therefore, pursuant to 1 O CFR 50.55a(z)(2), the licensee proposed an alternative to the applicable ASME Code requirements - to delay the repair or replacement activity until after Turkey Point 3 has exited the Cycle 29 refueling outage, as soon as practicable, but no later than 90 days from the authorization of the proposed alternative.
3.1.4 Proposed Alternative, Justification, and Duration The licensee proposed to delay the repair or replacement of the pipe until after Turkey Point 3 has exited the Cycle 29 refueling outage, as soon as practicable, but no later than 90 days from NRC's authorization of the proposed alternative. In lieu of the ASME Code,Section XI, subparagraph IWC-3132.2, the licensee proposed to temporarily accept the as-found condition (i.e., the through-wall flaw) to allow Turkey Point 4 to continue operation in MODE 1 until such time as the two Turkey Point 3 high head safety injection pumps are operable, and Turkey Point 3 is in MODES 1, 2, or 3. The licensee stated that it will implement all other applicable requirements of the ASME Code and ASME Code Case N-513-3 for which an alternative was not proposed and authorized by the staff.
The licensee visually characterized the through-wall flaw as a 3/4-inch long planar flaw oriented circumferentially and perpendicular to the pipe axis. The orientation and length was also confirmed by the application of penetrant test developer. The evidence of outer diameter pitting and previous operational experience at Turkey Point of other outer diameter initiated flaws from the salt laden environment surrounding the station provides reasonable assurance that the flaw is outer diameter initiated. Characteristics of outer diameter initiated flaws have an aspect ratio that the length is longer at the initiation site (the outer diameter) than the inner diameter. The licensee stated that ultrasonic examination could not be performed because of the small 3/4-inch pipe diameter.
The design pressure and temperature are 1750 psi and 300 °F, respectively. The maximum operating pressure and temperature are 1525 psi (post loss-of-coolant accident recirculation) and 205 °F at the high head safety injection pump discharge, respectively. The normal operating pressure is less than 50 psi. The subject pipe is located downstream of a restricting orifice from the high head safety injection pump and is normally vented to the refueling water storage tank, only seeing head height of the refueling water storage tank. The normal operating temperature is ambient (less than 100 °F). The licensee performed a flaw evaluation as required by ASME Code Case N-513-3 for the maximum and normal operating conditions and found the subject pipe to be acceptable.
ASME Code Case N-513-3 is applicable to a piping system that operates at a maximum temperature of 200 °F. The maximum operating temperature of the subject piping system is 205 °F, which would occur at the discharge of the high head safety injection pumps during the design-basis loss-of-coolant accident recirculation phase of emergency core cooling system operation. Because the pipe is not insulated, the temperature at the flaw location will be considerably less assuring that steam flashing that could cause cyclic stresses will not occur.
ASME Code Case N-513-3 is applicable to a piping system that operates at a maximum pressure of 275 psig. The subject piping is normally under the pressure of the refueling water storage tank head and occasionally slightly above that pressure for testing of the high head safety injection pumps and accumulator fills. In those cases, the pressure is well within the code case scope. When the system is in the recirculation mode during accident conditions, the maximum operating pressure of the subject pipe is 1525 psig. The methodology used to determine the structural integrity of the subject pipe is based on its physical characteristics and flaw characterization. The higher pressure is accounted for in the flaw analysis and results in lower allowable flaw size as expected. Furthermore, the flaw analysis that includes loading from an operating basis earthquake and safe shutdown earthquake shows significant margin between calculated and allowable stresses. Because the leakage rate calculated at the design pressure is very low (75.6 cubic centimeter per hour), lateral thrust forces resulting from the leak are negligible in comparison to the design pressure and seismic forces.
The ASME Code,Section XI, Non-mandatory Appendix C for flaw evaluation, as specified in ASME Code Case N-513-3, Section 3, is applicable, but it is restricted to 1-inch and greater nominal pipe size in other Code references (e.g., the ASME Code,Section XI, Section IWC-3641 ). Although the 3/4-inch pipe under evaluation is smaller than this limit, the equations in the analytical procedure in Appendix C for this particular flaw evaluation are relevant and are directly applicable to the smaller pipe size without modifications. The licensee stated in its submittal that for this situation, use of Appendix C procedure for 3/4-inch piping is justified.
The licensee stated that although the scope limitations of ASME Code Case N-513-3 are not met for the maximum operating conditions for the pipe, the normal operating temperatures and pressures are within the limitations of the code case. However, the guidance of the code case is followed because it provides criteria for analytical evaluation, and rules for temporary acceptance of flaws in piping. The licensee applied the provisions of ASME Code Case N-513-3, Section 2 as follows.
(a) The flaw size characterization is by visual examination and direct measurement (i.e., 3/4 inches in length and oriented circumferentially).
(b) The flaw is characterized as a through-wall planar flaw.
(c) The flaw was evaluated as a single flaw.
(d) The flaw evaluation was performed per the ASME Code,Section XI, Non-mandatory Appendix C.
(e) The licensee stated in its submittal that it will perform a monthly direct visual examination and the application of penetrant test developer to the area with the identified through-wall flaw to validate that the flaw has not grown and is still supported by the flaw evaluation.
(f) The licensee stated in its submittal that it will perform a daily visual walkdown of the leak location to confirm that the analysis conditions from the visual examinations remain valid (i.e., that there is no new significant leakage).
(g) The licensee calculated the maximum allowable through-wall flaw length of approximately 1.4 inches. This represents a factor of safety of 1.87 between the detected flaw length and the maximum allowable flaw size. The licensee did not perform a crack growth analysis. Instead, the licensee stated in its submittal that it will evaluate the leak daily and perform a penetrant test monthly. The licensee stated that negligible flaw growth is expected for the outer diameter stress corrosion cracking mechanism because the pipe's normal operating conditions of ambient temperature and low refueling water storage tank water head pressure are not significant drivers for stress corrosion cracking. The licensee noted that during the short duration of the proposed alternative, the flaw is not expected to grow significantly. The licensee stated that if the monthly measurement increases from the present by 1 /16 inches in either direction, allowing 1/16 inches for measurement uncertainty, then the growth rate will be re-examined to verify the structural analysis conclusions and predicted growth rate.
(h) The licensee stated in its submittal that it will repair or replace the degraded pipe segment after the 3A 4 kilovolt electrical bus has returned to service in Turkey Point 3 and the safety injection system TS completion times can be met without causing a shutdown with the Turkey Point 4 high head safety injection pumps 4A and 48 out of service but no later than 90 days after the alternative is authorized. The licensee evaluated the potential impact to offsite dose for the leakage rate that could be present during the design-basis accident. In accordance with the Updated Final Safety Analysis Report, Chapter 14, "Safety Analysis," and related documents, leakage identified in the emergency core cooling system must be tracked and managed such that the cumulative rate of all leaks does not exceed 2325 cubic centimeters per hour (cc/hr). The licensee estimated a potential leak rate of 75.6 cc/hr from the subject flaw for maximum pressure conditions at 1525 psig. This would result in a cumulative leakage rate from the emergency core cooling system of less than 1525.3 cc/hr for Turkey Point 3 and 1518.9 cc/hr for Turkey Point 4. As such, the leakage rate is within the allowable limit.
The licensee reviewed the potential for flooding from the leakage. As noted above, the maximum leakage rate has been determined to be 75.6 cc/hr. There is no equipment in the area that would be affected by the leak because the spray would be limited and captured within the penetration. The cumulative volume would be small and drain to the sumps in basement of the Auxiliary Building, where it would be contained and pumped to the Radwaste System.
3.2 Staff's Evaluation of Proposed Alternative The NRC staff evaluated the acceptability of the proposed alternative in terms of the flaw characterization, flaw evaluation, monitoring, flooding analysis, and extent of condition inspection in accordance with ASME Code Case N-513-3. The NRC staff also reviewed the validity of the licensee's hardship justification.
3.2.1 Flaw Characterization Per the licensee's evaluation, the leaking planar flaw is circumferentially oriented with a length of 314 inches long. The licensee measured the flaw length based on visual examinations and the penetrant test developer. The staff recognizes that the licensee was not able to size the flaw using ultrasonic examination because of the small pipe size. The staff finds that the degradation mechanism of the subject piping is most likely the outside diameter stress corrosion cracking because the stagnant operating conditions and chloride-rich environment in the coastal area where the plant is located are similar to the conditions described in NRC Information Notice 2011-04, "Contaminants and Stagnant Conditions Affecting Stress Corrosion Cracking in Stainless Steel Piping in Pressurized Water Reactors," dated February 23, 2011.4 The staff finds that the licensee satisfies the flaw characterization requirements of paragraphs (a) and (b) in ASME Code Case N-513-3.
4 ADAMS Accession No. ML103410363.
3.2.2 Flaw Evaluation Paragraph 3.1 (b) of ASME Code Case N-513-3 states, "For planar flaws in austenitic piping, the evaluation procedure in Appendix C shall be used.... " The subject pipe is made of stainless steel, and the defect is a planar flaw. Therefore, the licensee used the ASME Code,Section XI, Appendix C to perform the flaw evaluation as discussed above. However, the 2007 edition of the ASME Code,Section XI, Paragraph IWC-3641 limits the use of Appendix C methodology to 4-inch and greater nominal pipe size piping. The licensee used the limit load analysis in Appendix C-5300 to determine the allowable bending and membrane stresses for the pipe. The method in Appendix C-5300 references Appendix C-6330 for the Z factor value, which is based on the R/t ratio (R is the pipe radius, and tis the pipe wall thickness). The R/t ratio for the subject pipe is not within the range of permissible R/t values in Appendix C-6330. The subject pipe is 3/4-inch nominal pipe size and is less than the 4-inch nominal pipe size required in Paragraph IWC-3641. The staff recognizes that the flaw evaluation, in general, is an estimation and one of two methods to demonstrate the structural integrity of a pipe in service. The other method for demonstrating pipe structural integrity is to perform periodic inspections to verify the validity of the flaw evaluation. Because the licensee stated that it will verify the flaw evaluation results by periodically monitoring the subject pipe, the staff finds that the licensee's use of Appendix C-5300 to evaluate the subject flaw, even though the Appendix C method is not applicable to the subject piping, is acceptable.
The design pressure and temperature of the affected piping are 1750 psi and 300 °F, respectively. The maximum operating pressure and temperature are 1525 psi during post loss-of-coolant accident recirculation and 205 °F at the high head safety injection pump discharge, respectively. The subject pipe is located downstream of a restricting orifice from the high head safety injection pump, is normally vented to the refueling water storage tank, and is at the head height of the refueling water storage tank. The normal operating pressure is less than 50 psi. The normal operating temperature is ambient (i.e., less than 100 °F).
The licensee included various temperatures and pressures in the flaw evaluation. The licensee also included appropriate loading combinations, including loadings from an operating basis earthquake and a safe shutdown earthquake, in its analysis.
Paragraph 2( e) of ASME Code Case N-513-3 permits periodic inspection of the flaw to determine flow growth in lieu of a crack growth analysis. The licensee did not perform a crack growth analysis; however, the licensee stated in its submittal that it will perform periodic inspections to monitor the flaw growth. The licensee calculated an allowable flaw length of 1.4 inches. The outside diameter of the 3/4-inch pipe is 1.05 inches, and its circumference is about 3.3 inches. The allowable flaw size of 1.4 inches is about 42 percent of the pipe circumference. The current flaw length of 0.75 inches is about 23 percent of the pipe circumference. A margin factor of approximately 2 exists between the existing flaw length and the allowable flaw length.
The licensee stated in its submittal that it will repair the subject pipe as soon as Turkey Point 3 exits its Cycle 29 refueling outage. The maximum duration for the flaw to grow from current flaw length to the allowable flaw length is 90 days from March 22, 2017, which was when the staff verbally authorized the proposed alternative. The staff finds that the flaw likely will not grow from 0.75 inches to 1.4 inches within 90 days based on the current operating conditions (i.e.,
low temperature and pressure). In addition, if the flaw grows more than 1/16 inches, the licensee will take corrective actions.
Notwithstanding the proposed deviations from the analysis requirements of the ASME Code,Section XI, Appendix C and Paragraph IWC-3641, the staff finds that the licensee's flaw evaluation is acceptable because the licensee will perform periodic monitoring to verify the crack growth to ensure that the flaw will not exceed the allowable length.
3.2.3 Monitoring The staff finds that the licensee use of ASME Code Case N-513-3 to perform (a) daily visual walkdowns of the leak location to confirm that the analysis conditions from the visual examinations remain valid (i.e., no new significant leakage), and (b) a surface examination every 30 days using a penetrant test developer, is acceptable.
3.2.4 Flooding Analysis The staff determined that the current leakage rate of 75.6 cc/hr is small. There is no equipment in the area that would be affected by the leak because the spray would be limited and captured within the floor penetration. The leakage can be drained to the sumps in the basement of the Auxiliary Building, where it would be contained and pumped to the Radwaste System. The staff finds that there is reasonable assurance that no safety-related components or equipment will be affected by the leakage for the duration of the proposed alternative. The staff finds that the licensee has performed an acceptable flooding analysis.
3.2.5 Extent of Condition Paragraph 5(a) of ASME Code Case N-513-3 requires, in part, that the most susceptible locations shall be identified, and that a sample size of at least five of the most susceptible and accessible locations or, if fewer than five, all susceptible and accessible locations shall be examined within 30 days of detecting the flaw. The licensee performed an extent of condition inspection on five additional pipes in locations where similar operating conditions exist. The licensee did not observe other indications on the pipes. The licensee stated in its submittal that any additional discrepancies will be addressed under the corrective action program. The staff finds that the licensee performed an adequate extent of condition inspection and satisfied paragraph 5(a) of ASME Code Case N-513-3.
3.2.6 Hardship Justification The staff finds that requiring the plant to shut down to repair the subject pipe in accordance with the ASME Code,Section XI is a hardship because performing the repair would place the plant into an unsafe system configuration, and an unscheduled shutdown prior to the scheduled refueling outage on Unit 3 would strain the systems and components in the plant. The staff finds that considering the corresponding adverse impact on the plant, performing the ASME Code repair or replacement would not increase the level of plant quality and safety.
In summary, the staff finds that based on the flaw evaluation, proposed monitoring, and low pressure and temperature of the normal operating condition of the subject pipe, the licensee has demonstrated reasonable assurance that the structural integrity of the subject pipe will be maintained for the short duration of the proposed alternative.
4.0 CONCLUSION
As set forth in this safety evaluation, the staff has determined that complying with the ASME Code requirements would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. Furthermore, the staff concludes that the proposed alternative in Relief Request No. 5 provides reasonable assurance of structural integrity of the subject piping. Accordingly, the staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the staff authorizes the use of Relief Request No. 5 at Turkey Point 4 for up to 90 days from March 22, 2017, which was the date of the staff's verbal authorization.
All other requirements of the ASME Code,Section XI for which relief or a proposed alternative was not specifically requested and authorized by the NRC remain applicable, including the third party review by the Authorized Nuclear In-service Inspector.
Principal Contributor: J. Tsao Date: May 10, 2017
SUBJECT TURKEY POINT NUCLEAR GENERATING UNIT NO. 4 - SAFETY EVALUATION FOR RELIEF REQUEST NO. 5 FOR FIFTH 10-YEAR INSERVICE INSPECTION INTERVAL (CAC NO. MF9459) DATED MAY 10, 2017 DISTRIBUTION:
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