ML19171A357
| ML19171A357 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/27/2019 |
| From: | Lisa Regner Plant Licensing Branch III |
| To: | Fessler P DTE Electric Company |
| Goetz S, NRR/DORL/LPLIII, 415-8004 | |
| References | |
| EPID L-2019-LLR-0039, EPID L-2019-LLR-0040 | |
| Download: ML19171A357 (11) | |
Text
June 27, 2019 Mr. Paul Fessler, Senior Vice President and Chief Nuclear Officer DTE Energy Company Fermi 2 -260 TAC 6400 North Dixie Highway Newport, MI 48166
SUBJECT:
FERMI 2- NUCLEAR POWER PLANT - RELIEF FROM THE REQUIREMENTS OF THE ASME CODE (EPID L-2019-LLR-0039 AND EPID L-2019-LLR-0040)
Dear Mr. Fessler:
By letter dated March 27, 2019, Agencywide Documents Access and Management System (ADAMS) Accession No. ML19086A284, DTE Electric Company (DTE, the licensee), requested the use of an alternative to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) requirements at Fermi 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.55a(z)(1), the licensee requested to use proposed alternatives PRR-002 and PRR-003 on the basis that the alternatives provide an acceptable level of quality and safety. PRR-002 is related to alternative vibration acceptance criteria for smooth running pumps and PRR 003 is for service water pump suction pressure accuracy. For both relief requests (RRs), the licensee requested alternative test plans in lieu of certain inservice testing (IST) requirements of the 2012 Edition of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) at Fermi 2.
The U.S. Nuclear Regulatory Commission (NRC) staff finds that the proposed alternatives described in RRs PRR-002 and PRR-003 provide an acceptable level of quality and safety for components listed in Tables 1 and 2 of the enclosed safety evaluation. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1).
All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable.
Therefore, the NRC staff authorizes the proposed alternatives in PRR-002 and PRR-003 for the fourth 10-year IST interval at Fermi 2 which is currently scheduled to start on February 17, 2020.
P. Fessler If you have any questions, please contact the Sujata Goetz, at 301-415-8004 or via e-mail at Sujata.Goetz@nrc.gov.
Sincerely,
/RA/ Joel S. Wiebe for Lisa M. Regner, Acting Branch Chief Plant Licensing Branch 3 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341
Enclosure:
Safety Evaluation cc: ListServ
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE RELIEF REQUESTS PRR-002 AND PRR-003 RELATED TO THE INSERVICE TESTING PROGRAM FOURTH 10-YEAR INTERVAL DTE ELECTRIC COMPANY FERMI 2 DOCKET NO. 50-341
1.0 INTRODUCTION
By letter dated March 27, 2019, Agencywide Documents Access and Management System (ADAMS) Accession No. ML19086A284, DTE Electric Company (DTE, the licensee), requested the use of alternatives to certain American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) requirements at Fermi 2 for relief requests (RRs) PRR-002 and PRR-003. RR PRR-002 is related to alternative vibration acceptance criteria for smooth running pumps and RR PRR 003 is related to service water pump suction pressure accuracy. For both RRs, the licensee requested alternative test plans in lieu of certain inservice testing (IST) requirements of the 2012 Edition of the American Society of Mechanical Engineers (ASME)
Code for Operation and Maintenance of Nuclear Power Plants (OM Code) at Fermi 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.55a(z)(1), the licensee requested to use proposed alternatives for PRR-002 and PRR-003 on the basis that the alternatives provide an acceptable level of quality and safety.
2.0 REGULATORY EVALUATION
Regulation 10 CFR, Section 50.55a(f), Inservice Testing Requirements, requires, in part, that IST of certain ASME Code Class 1, 2, and 3 components must meet the requirements of the ASME OM Code and applicable addenda, except where alternatives have been authorized pursuant to paragraphs 10 CFR 50.55a(z)(1) or 10 CFR 50.55a(z)(2).
In proposing alternatives, a licensee must demonstrate that the proposed alternatives provide an acceptable level of quality and safety (10 CFR 50.55a(z)(1)) or compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety (10 CFR 50.55a(z)(2)).
Enclosure
3.0 TECHNICAL EVALUATION
3.0.1 Applicable ASME OM Code Both PRR-002 and PRR-003 are requests for alternative test plans in lieu of certain IST requirements of the 2012 Edition of the ASME OM Code for the IST program at Fermi 2 for the fourth interval which is currently scheduled to start on February 17, 2020.
3.1.1 Licensees Relief Request PRR-002 ASME OM Code Requirements:
ISTB-3300(a) Reference Values, states that Initial reference values shall be determined from the results of testing meeting the requirements of ISTB-3100, Preservice Testing, or from the results of the first inservice test.
Table ISTB-5121-1 Centrifugal Pump Test Acceptance Criteria Table ISTB-5221-1 Vertical Line Shaft Centrifugal Pump Test Acceptance Criteria Table ISTB-5321-1 Positive Displacement Pump (Except Reciprocating) Test Acceptance Criteria Alternative testing is requested for the pumps listed in Table 1 on page 3.
The licensee in its request, stated, in part:
Reason for Request
The listed pumps have at least one vibration reference value (Vr) that is currently less than or equal to 0.04 inches per second (ips). Small values for Vr result in very small acceptable ranges for pump operation. The acceptable ranges are defined in Tables ISTB-5121-1, ISTB-5221-1, and ISTB-5321-1, as less than or equal to 2.5Vr. Based on such a small acceptable range, a smooth-running pump could be subject to unnecessary corrective action.
Proposed Alternative To avoid unnecessary increased frequency testing or corrective actions on pumps which are performing satisfactorily and with very low baseline vibration, a minimum velocity measurement value (Vr) of 0.04 inches per second (ips) will be established for velocity reference values. This minimum value will be applied to individual vibration locations where the measured reference value is less than or equal to 0.04 ips and utilized in the calculation of acceptable ranges specified in Tables ISTB-5121-1, ISTB-5221-1, and ISTB-5321-1. Therefore, the acceptance range as specified in Tables ISTB-5121-1, ISTB-5221-1, and ISTB-5321-1, will be less than or equal to 0.100 ips, the alert range will be greater than 0.100 to 0.240 ips, and the required action range will be greater than 0.240 ips.
Table 1 Pump ID Function ASME OM Code Group Class E1151C001A Residual Heat Removal (RHR) Service Water Pump 3 A (SWP) A E1151C001B RHR SWP B 3 A E1151C001C RHR SWP C 3 A E1151C001D RHR SWP D 3 A P4400C001A Emergency Equipment Cooling Water (EECW) Division 3 B 1 Pump P4400C001B EECW Division 2 Pump 3 B P4400C002A EECW Makeup Division 1 Pump 3 B P4400C002B EECW Makeup Division 2 Pump 3 B P4500C002A Emergency Equipment Service Water (EESW) South 3 A Pump P4500C002B EESW North Pump 3 A R3000C001 Emergency Diesel Generator (EDG) 11 Diesel Fuel Oil 3 B Transfer Pump A R3000C002 EDG 12 Diesel Fuel Oil Transfer Pump A 3 B R3000C003 EDG 11 Diesel Fuel Oil Transfer Pump B 3 B R3000C004 EDG 12 Diesel Fuel Oil Transfer Pump B 3 B R3000C009 EDG 13 Diesel Fuel Oil Transfer Pump A 3 B R3000C0010 EDG 14 Diesel Fuel Oil Transfer Pump A 3 B R3000C011 EDG 13 Diesel Fuel Oil Transfer Pump B 3 B R3000C012 EDG 14 Diesel Fuel Oil Transfer Pump B 3 B R3001C005 EDG 11 Diesel Generator (DG) SWP 3 A R3001C006 EDG 12 DG SWP 3 A R3001C007 EDG 13 DG SWP 3 A R3001C008 EDG 14 DG SWP 3 A T4100C040 Control Center Heating Ventilating and Air Conditioning 3 A (CCHVAC) South Chilled Water Pump T4100C041 CCHVAC North Chilled Water Pump 3 A For very small reference values, hydraulic noise and instrumentation error can be a significant portion of the reading and therefore affect the repeatability of subsequent measurements. Also, experience gathered from the predictive maintenance program has shown that changes in vibration levels in the range of 0.04 ips are not typically indicative of degradation in pump or motor condition.
When new reference values are established per ISTB-3310, ISTB-3320 or ISTB-6200(c),
the measured parameters will be evaluated for each location to determine if the provisions of this relief request remain applicable. If the measured Vr is greater than 0.04 ips, the requirements of ISTB-3300 will be applied. Conversely, if a measured Vr is less than or equal to 0.04 ips, a minimum value of 0.04 ips will be used for Vr for the pumps included in the list of pumps. In addition to the requirements of ISTB, the pumps in the ASME Inservice Testing Program are included in the Fermi 2 Vibration Monitoring Program scope. The Vibration Monitoring Program currently employs vibration monitoring and analysis beyond that required by ISTB when the pumps are tested quarterly.
All data is collected currently utilizing an accurate data acquisition system, downloaded into the Vibration Monitoring Program software and then analyzed for vibration magnitude and discrete frequencies. Components exhibiting abnormal vibration trends would be subjected to more advanced diagnostics.
If the measured parameters are outside the normal operating range or are determined by analysis to be trending toward an unacceptable degraded state, appropriate actions are taken that may include:
Increased monitoring to establish rate of change, Review of component specific information to identify cause, and Removal of the pump from service to perform maintenance.
Preventive Maintenance (PM) program coverage typically entails, depending on the specific pump, oil sampling, lubrication, phase to phase winding tests, insulation checks, exterior cleaning, motor testing, cleaning, and inspections. All the pumps in the IST program will remain in the PM and Vibration Monitoring program scope even if certain pumps have very low vibration readings and are considered to be smooth running pumps.
This proposed alternative will be utilized for the entire fourth 10-year interval. The fourth interval begins on February 17, 2020.
3.1.2 NRC Staff Evaluation The ASME OM Code requires that the vibration of all safety-related pumps be measured. For centrifugal pumps, paragraph ISTB-3540(a), notes that vibration measurements shall be taken in a plane approximately perpendicular to the rotating shaft in two approximately orthogonal directions on each accessible pump-bearing housing. Measurement shall also be taken in the axial direction on each accessible pump thrust bearing housing. For vertical line shaft pumps, paragraph ISTB-3540(b) requires vibration measurements be taken on the upper motor bearing housing in three orthogonal directions including the axial direction. For reciprocating pumps, paragraph ISTB-3540(c) requires the location of the vibration measurement shall be on the bearing housing of the crankshaft approximately perpendicular to both the crankshaft and the line of the plunger travel. These measurements are required to be compared with the ASME OM Code vibration acceptance criteria as specified in Table ISTB-5100-1, Table 5221-1, or Table ISTV-5321-1 to determine if the measured values are acceptable.
Tables ISTB-5100-1, ISTB-5221-1 and ISTB-5321-1 states, in part, that if during an IST a vibration measurement on a centrifugal pump exceeds 2.5 times the reference value (Vr),
previously established as required by ISTB-3300, the pump is considered to be in the alert range. The frequency of testing is then doubled in accordance with ISTB-6200(a) until the cause of the deviation is determined, the condition is corrected, and the vibration level returns below the alert range. Pumps, whose vibration is measured at greater than six times Vr are considered to be in the required action range and must be declared inoperable until the cause of the deviation has been determined and the condition is corrected. Per ISTB-3300, the vibration reference values shall be established only when the pump is known to be operating acceptably.
For pumps whose absolute magnitude of vibration is an order of magnitude below the absolute vibration limits in Tables ISTB-5100-1, ISTB-5221-1 and ISTB-5321-1, a relatively small increase in vibration magnitude may cause a pump to enter the alert or required action range even though the pump is operating acceptably. The pump may enter these ranges due to
variations in flow, instrument accuracies, or other noise sources that would not be associated with degradation of the pump. Pumps that operate with these low vibrations are typically referred to as smooth running. Since the acceptable range for a smooth running pump is so small, the pump could be subjected to unnecessary corrective action due to entry into the alert or action ranges.
The U.S. Nuclear Regulatory Commission (NRC) has previously authorized a minimum vibration level of 0.05 ips for smooth running pumps at several nuclear plants. However, only monitoring vibration of smooth running pumps has been shown to be insufficient for determining pump degradation. At one plant, the NRC authorized a minimum reference value of 0.1 ips. A pump bearing at this plant experienced a significant degradation even though the pump vibration levels were below the minimum reference value in the approved alternative. The bearing degradation was discovered during predictive maintenance program activities.
The licensees alternative combines a minimum vibration value of 0.04 ips for smooth running pumps with additional monitoring via vibration monitoring program, which includes vibration analysis beyond that required by ASME OM Code. In addition, the Fermi 2 preventive maintenance program includes periodic oil sampling, lubrication, motor testing, cleaning, and inspections, as applicable. The licensee notes in their alternative request that if any of the measured parameters are outside of the normal operating range or are determined by analysis to be trending towards an unacceptable degraded state, appropriate actions will be taken.
These actions include increased monitoring to establish a rate of change, review of component specific information to identify the cause of the condition, and removal of the pump from service to perform maintenance. The proposed alternative is consistent with the objectives of the IST program, which is to monitor degradation in safety-related components.
Based on the minimum vibration reference value of 0.04 ips noted in this request and the proposed vibration monitoring and preventive maintenance programs, the NRC staff finds that the alert and required action limits specified in the request should address previously undetected pump problems and provide an adequate indication of pump performance. The licensees additional maintenance programs are designed to detect problems involving unacceptable mechanical conditions in advance of when a smooth-running pump may reach the overall vibration alert or action limits. Therefore, the NRC finds that the proposed alternative will provide an acceptable level of quality and safety.
3.2.1 Licensees Relief Request PRR-003 ASME OM Code Requirements:
ISTB-3510(a) Accuracy states that Instrument accuracy shall be within the limits of Table ISB-3510-1. If a parameter is determined by analytical methods instead of measurement, then the determination shall meet the parameter accuracy requirement of Table ISTB-3510-1 (e.g., flow rate determination shall be accurate to within +/-2 (%) of actual). For individual analog instruments, the required accuracy is a percent of full-scale. For digital instruments, the required accuracy is over the calibrated range. For a combination of instruments, the required accuracy is loop accuracy.
Table ISTB-3510-1 Required Instrument Accuracy.
Alternative testing is requested for the following pumps:
Table 2 Pump ID Function ASME OM Code Group Class E1151C001A Residual Heat Removal (RHR) Service Water Pump 3 A (SWP) A E1151C001B RHR SWP B 3 A E1151C001C RHR SWP C 3 A E1151C001D RHR SWP D 3 A P4500C002A Emergency Equipment Service Water (EESW) South 3 A Pump P4500C002B EESW North Pump 3 A R3001C005 EDG 11 Diesel Generator (DG) SWP 3 A R3001C006 EDG 12 DG SWP 3 A R3001C007 EDG 13 DG SWP 3 A R3001C008 EDG 14 DG SWP 3 A The licensee states, in part:
Reason for Request
Table ISTB-3510-1 specifies the pressure instrument accuracy to be +/-0.5% during a comprehensive pump test. Due to the design of these service water pumps (vertical line shaft), the suction pressure (INLPR) is determined using measurement of Residual Heal Removal (RHR) reservoir level and correlation to suction lift pressure. The ASME OM code does not specify accuracy requirements for level instrumentation when used as a method to obtain suction lift pressure.
Proposed Alternative Fermi 2 proposes to perform the quarterly testing of these pumps using the existing
+/-0.92% accurate level instrumentation for determining suction pressure.
The instrumentation for level measurement of the RHR reservoir is calibrated to +/-0.73% at full scale (+/-0.22 ft [feet] at 30 ft). The calibration cardinal point of 24 ft bounds readings obtained for pump surveillance testing which range between 4.8 pounds per square inch (psi) and 5.4 psi based on a review of pump testing data obtained in approximately the last 5 years. The corresponding reservoir level is 27.0 ft (5.4 psi) to 28.4 ft (4.8 psi). The accuracy at that cardinal point is +/-0.92% (+/-0.22 ft at 24 ft).
Differential pressure is determined by adding the suction lift pressure derived from RHR reservoir level to the pump discharge pressure. Suction lift pressure is determined using a table relating RHR reservoir level to suction lift in psi (a copy of this table is in each surveillance procedure).
The critical point accuracy of the existing level instrument is +/-0.92% (for the 24 ft cardinal point). For the nominal INLPR pressure reading of 5.4 psi this equates to a maximum
possible error of 5.4 x 0.0092 = 0.050 psi which is the conservative side of the INLPR pressure testing range with respect to accuracy. For the comprehensive test of these pumps, the Code required accuracy for pressure is 0.5%, or 0.027 psi at a measured INLPR of 5.4 psi. The difference between the permanently installed instrument accuracy and the Code required 0.5% accuracy amounts to 0.023 psi.
Temporary digital instrumentation is used to measure the discharge pressure (DISPR) of these pumps. The accuracy of the DISPR measurements is 0.5% of reading or better.
The discharge pressure of the subject service water pumps has a range of between 35.8 and 59.6 psi based on recent data depending on the specific pump. To illustrate the discharge pressure accuracy, the high DISPR reading of 59.6 psi will be used. This discharge pressure has an error of 59.6 x 0.005 = 0.30 psi based on an accuracy requirement of +/-0.5%. This is conservative as most modern pressure gauges, such as a Crystal XP2i, are more accurate compared to the ASME OM Code requirement of +/-0.5%.
Also, the higher discharge pressure is more conservative in comparison to a lower discharge pressure in terms of full scale instrument accuracy. Combining the INLPR error of 0.050 psi and the DISPR error of 0.30 psi using square root sum of the squares gives an overall error of +/-0.30 psi for the P [differential pressure] value of 65 psid [per square inch differential]. This represents a +/-0.47% accuracy of the P measurement.
The differential pressure parameter is affected primarily by the accuracy of the discharge pressure of the pumps. The suction lift pressure derived from RHR reservoir level has lower impact on the overall calculation of pump differential pressure.
The RHR reservoir level transmitter is manufactured by Rosemount, with Model number 1151DP5E12. This instrument is a steel diaphragm style level instrument. The instrument loop calibration includes the transmitter, power supply and digital level indicator / recorder.
In conclusion, Fermi 2 proposes to perform the quarterly testing of these pumps using the existing +/-0.92% accurate level instrument for determining suction pressure. All other measurements and methods will meet the 0.5% accuracy requirements for determining pump differential pressure. Use of this instrumentation and accuracy during quarterly testing supports Comprehensive Pump Testing instrument requirements.
3.2.2 NRC Staff Evaluation Service water pumps listed in Table 2 of Section 3.2.1 of this safety evaluation (SE) are vertical line shaft centrifugal pumps and considered to be Group A as defined by the ASME OM Code, which states that Group A pumps are pumps that are operated continuously or routinely during normal operation, cold shutdown, or refueling operations. The ASME OM Code requires Group A vertical line shaft pumps to be tested quarterly by test procedure ISTB-5221 and tested biennially by the comprehensive test procedure ISTB-5223. Both tests require that the pump operate at a specific flow reference point or alternatively at a specific differential pressure point.
When performing the comprehensive pump test, the accuracy of the instrumentation for measuring the pump pressure must be within +/-0.5% per Table ISTB-3510-1.
The licensee has proposed to perform quarterly and comprehensive pump testing using the installed RHR reservoir level instrumentation which has a loop accuracy of +/-0.92% to measure the pump suction pressure. Temporary instrumentation with an accuracy of 0.5% of reading or better will be used to measure the pump discharge pressure. These pump pressure measurements will be applied to the quarterly testing of the pumps. This exceeds the ASME
OM Code accuracy requirement of +/-2% for the quarterly tests. For the comprehensive and preservice tests, the measured pressure accuracy requirement is 0.5%. As noted in the licensee discussion, the difference between the permanently installed instrument accuracy compared to the ASME OM Code requirement accuracy of 0.5% results in a value considered insignificant when monitoring for degradation. Therefore, the NRC staff concludes that the licensee's proposed alternative provides an acceptable level of quality and safety.
4.0 CONCLUSION
As set forth above, the NRC staff finds that the proposed alternatives described in requests PRR-002 and PRR-003 provides an acceptable level of quality and safety for components listed in Tables 1 and 2 of this SE. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(1) and is in compliance with the ASME Codes requirements. Therefore, the NRC staff authorizes the proposed alternatives in PRR-002 and PRR-003 for the fourth 10-year IST interval at Fermi 2 which is currently scheduled to start on February 17, 2020.
All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject requests for relief remain applicable.
Principle Contributor: M. Farnan, NRR Date of issuance: June 27, 2019
ML19171A357 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/EMIB/BC NRR/DORL/LPL3/BC NAME SGoetz SRohrer SBailey LRegner (JWiebe for)
DATE 06/27/19 06/26/19 06/05/19 06/27/19