ML23250A273
| ML23250A273 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 09/07/2023 |
| From: | Shilpa Arora NRC/NRR/DORL/LPL3 |
| To: | Frank E DTE Electric Company |
| References | |
| L-2023-LLA-0069 | |
| Download: ML23250A273 (7) | |
Text
From: Surinder Arora Sent: Thursday, September 7, 2023 2:51 PM To: Eric Frank Cc: Roxanne Vonhabsburg; Jeff Whited
Subject:
Fermi 2 - Request for Additional Information for License Amendment Request to Revise TS 3.8.1, "AC Sources - Operating," Surveillance Requirement 3.8.1.12 (EPID: L-2023-LLA-0069)
Mr. Frank, By letter dated May 5, 2023 (Agencywide Documents Access Management System (ADAMS) Accession No. ML23128A017), DTE Electric Company (the licensee) submitted, for the NRC staff review and approval, a license amendment request to revise Fermi 2 Technical Specification (TS) 3.8.1, AC Sources -Operating, Surveillance Requirement 3.8.1.12.
The U.S. Nuclear Regulatory Commission (NRC) staff is reviewing the above request and has determined that response to the following request for additional information (RAI) is needed to complete its review. The draft RAI was emailed to you on September 5, 2023, for your review. Ms. Vonhabsburgs email, dated September 7, 2023, confirmed that DTE did not need a clarification for any of the questions in the draft RAI.
Therefore, this email provides you the final RAI without any changes. As stated in my previous email, your response to this RAI is expected within 30 days from September 5, 2023, unless a request is received to extend the response date. Please note that the extension in the response date could impact the final issuance schedule of the amendment.
Thank you, Docket No. 50-341 EPID: L-2023-LLA-0069 Surinder Arora, P. E.
Project Manager, Fermi 2 and Dresden 2 & 3 NRR/DORL/LPL3 surinder.arora@nrc.gov 301-415-1421 REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO REVISE SURVEILLANCE REQUIREMENT 3.8.1.12 FERMI 2 DTE ELECTRIC COMPANY DOCKET NO. 50-341
By letter dated May 5, 2023 (Agencywide Document Access Management System (ADAMS)
Accession No. ML23128A017), DTE Electric Company (DTE, the licensee) requested an amendment to the Renewed Facility Operating License No. NPF-43 for Fermi 2 Power Plant (Fermi 2). The proposed amendment would revise technical specification (TS) 3.8.1, AC Sources - Operating, surveillance requirement (SR) 3.8.1.12. Specifically, the proposed amendment would add a requirement to verify the crankcase overpressure automatic trip for each emergency diesel generator (EDG) is bypassed on an actual or simulated emergency start signal. The U.S. Nuclear Regulatory Commission (NRC) staff has determined that the following additional information is needed to complete its review of the license amendment request (LAR).
Regulatory Requirements (EEEB):
Appendix A to Title 10 of the Code of Federal Regulations (10 CFR) Part 50, General Design Criterion (GDC) 17, Electric power systems, requires, in part, that an onsite electric power system and an offsite electric power system shall be provided to permit functioning of structures, systems, and components important to safety. GDC 18, Inspection and testing of electric power systems, requires, in part, that electric power systems important to safety shall be designed to permit appropriate periodic inspection and testing. The systems shall be designed with a capability to test periodically the operability, functional performance of the components of the systems onsite power source and the operability of the systems as a whole, and the full operation sequence that brings the systems into operation.
Regulatory Guide (RG) 1.9, Revision 2, Selection, Design, and Qualification of Diesel-Generator Units Used as Standby (Onsite) Electric Power Systems at Nuclear Power Plants, endorses IEEE Standard (Std) 387-1977, IEEE Standard Criteria for Diesel-Generator Units Applied as Standby Power Supplies for Nuclear Power Generating Stations. RG 1.9, Regulatory Position C.7 states, in part, that a trip may be bypassed under accident conditions, provided the operator has sufficient time to react appropriately to an abnormal diesel-generator unit condition.
Request for Additional Information (EEEB)
EEEB RAI #1 Revision 2 of RG 1.9 states:
Section 5.6.2.2, Automatic Control, of IEEE Std. 387-1977 pertains to automatic startup requirements and their relationship to other operating modes. In conjunction with Section 5.6.2.2, engine-overspeed and generator-differential trips may be implemented by a single-channel trip. All other diesel-generator protective trips should be handled in one of two ways: Either, (1) a trip should be implemented with two or more independent measurements for each trip parameter with coincident logic provisions for trip actuation, or (2) a trip may be bypassed under accident conditions, provided the operator has sufficient time to react appropriately to an abnormal diesel-generator unit condition.
In its LAR, the licensee stated:
DTE is performing a modification for Fermi 2 that will change the high crankcase pressure trip from an essential trip to a non-essential trip for all four EDGs 11, 12,
13, and 14. This will ensure that during an emergency run (such as during a [loss of offsite power] LOOP and tornado event), the EDG will not trip on high crankcase pressure and all essential loads fed from the EDGs will remain powered.
The licensee further stated RG 1.9, Rev. 2 provides design guidance for handling of diesel generator protective trips. Fermi 2 has not committed to this regulatory guide, however, the plant does conform to it with exceptions, as described in the Fermi 2 Updated Final Safety Analysis Report (UFSAR) Appendix A.1.9.
The NRC staff notes that Revision 2 of RG 1.9 allows an EDG protective trip (except for engine-overspeed and generator-differential trips) to be bypassed to prevent an undesired EDG shutdown under accident conditions. However, the LAR proposed bypassing an EDG protective trip during an emergency run (such as during a LOOP and tornado event). The NRC staff requests the following:
- 1. A clarification of whether Fermi 2 defines a LOOP and tornado event as an accident condition.
- 2. If a LOOP and tornado event is not an accident condition, explain how bypassing an EDG protective trip during this condition would satisfy RG 1.9. Further, if bypassing an EDG trip under a non-accident condition results the EDG damage and rendering the EDG unavailable for an accident, explain how the proposed change meets the requirement of GDC 17.
EEEB RAI #2 In the second paragraph of Section 3.0 of the LAR, the licensee stated, in part (underline added):
The EDG manufacturer, Fairbanks Morse Engine, has identified five failure modes which could result in high crankcase pressure. Any one of these failure modes could occur from a random single failure mechanism. These failure modes are:
- 1. Broken piston rings;
- 2. Cracked pistons;
- 3. Blower seal failure;
- 4. Liner water seal failure; and,
- 5. Failed crankcase vacuum system.
Further, Section 3.0 of the LAR states, in part:
The fifth mode of failure, failed crankcase vacuum system, is the most common and does not lead to immediate engine degradation. Therefore, in the current configuration, the effect of a crankcase vacuum system failure would be an unnecessary EDG shutdown in Emergency mode, resulting in a failure of the EDG to perform its safety-related function.
The NRC staff notes that there are differences between, both in meaning and the impact of, the terms failed crankcase vacuum system and high crankcase pressure. The failure of the crankcase vacuum system is one of five failure modes that contribute to the EDG high crankcase pressure. High crankcase pressure, on other hand, contributes to crankcase explosion and catastrophic damage to the EDG engine. It appears that the LAR uses the two terms interchangeably.
The discussion of failed crankcase vacuum system without sufficient evaluation/justification of the other failure modes is not sufficient basis for removing high
crankcase pressure from the automatic trip bypass exceptions in SR 3.8.1.12. Explain how the proposed change demonstrates that allowing the crankcase overpressure trip to be bypassed, is acceptable for the purpose of protecting the EDG from further internal engine component failures caused by the other four failure modes.
EEEB RAI #3 The third paragraph of Section 3.0 of the LAR states, in part:
However, by the time any of these four failure modes would activate a high crankcase pressure trip, significant damage to the affected engine would have already occurred requiring a lengthy repair process. As such, the EDG out-of-service time is not significantly affected by blocking the high crankcase pressure trip for the first four failure modes.
The LAR does not include the evaluation and justification to support the above statements. Provide analysis available to support the claims that:
- 1. 1. By the time any of the four failure modes would activate a high crankcase pressure trip, significant damage to the affected engine would have already occurred.
- 2. 2. The EDG out-of-service time is not significantly affected by blocking the high crankcase pressure trip for the first four failure modes.
EEEB RAI #4 In Section 2.3 of the LAR, the licensee stated:
Within the current design, one of the essential trips of the EDGs is high crankcase pressure. During any mode of operation, the EDG will trip on high crankcase pressure to prevent crankcase explosion and catastrophic damage to the diesel engine.
The third paragraph of Section 3.0 of the LAR states, in part:
Furthermore, it has been determined that allowing an EDG to operate in a high crankcase pressure condition would not increase the possibility of failure of any of the three unaffected EDGs.
The LAR does not provide an analysis that supports the claim that theres no increase in possibility of failure for any of the three unaffected EDGs. Provide any analysis available to support the claim that the unaffected EDGs would not have increased failure possibility. Also, with respect to missile protection (i.e., crankcase explosion due to high pressure), explain how the three unaffected EDGs would not be impacted, provide their locations, and provide the distance from each of these EDGs to the affected EDG.
EEEB RAI #5 Revision 2 of RG 1.9 states, in part:
a trip may be bypassed under accident conditions, provided the operator has sufficient time to react appropriately to an abnormal diesel-generator unit condition.
In Section 3.0 of the LAR, the licensee stated, in part:
In the event of an engine malfunction in which the EDG crankcase pressure reaches the alarm setpoint, operators would be alerted of the condition by
annunciation in the Main Control Room and at the local control panel. Local indication is available to monitor the high crankcase pressure condition. Plant operating procedures instruct the operators to monitor certain EDG parameters when an emergency start signal is present. A precaution will be added for monitoring high crankcase pressure conditions as part of the modification process. This will ensure the operator has sufficient time to react appropriately to this condition.
The LAR does not contain an evaluation to support the claim that the added precaution will ensure that an operator will have sufficient time to react to the stated condition.
Provide an analysis that demonstrates there is adequate operator response time to the EDG crankcase high pressure alarm to support this claim.
Regulatory Requirements (EMIB):
10 CFR 50.36, Technical Specifications, establishes regulatory requirements related to the contents of the TS. Specifically, 10 CFR 50.36(c)(2) states, in part, Limiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility. In addition, 10 CFR 50.36(c)(3) states, Surveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions of operation will be met.
10 CFR Part 50, Appendix A, General Design Criterion 18, Inspection and Testing of Electrical Power Systems, states the following:
Electrical power systems important to safety shall be designed to permit appropriate periodic inspection and testing of important areas and features such as wiring, insulation, connections, and switchboards, to assess the continuity of the systems and the condition of their components. The system shall be designed with a capability to test periodically (1) the operability and functional performance of the components of the systems, such as onsite power sources, relays, switches, and buses, and (2) the operability of the systems sequence that brings the systems into operation, including operation of applicable portions of the protection system, and the transfer of power among the nuclear power unit, the offsite power system, and the onsite power system.
Request for Additional Information (EMIB)
EMIB RAI #1 The LAR proposes to revise the TS to specify that the crankcase overpressure automatic trip will be bypassed for an actual or simulated emergency start signal for each EDG. If the EDG start signal is generated by a simulated emergency, why will the crankcase overpressure automatic trip be bypassed if there is no emergency?
EMIB RAI #2 The justification for the LAR focuses on an inadvertent trip of the EDG on crankcase overpressure during a tornado with a loss of offsite power (LOOP) because of the atmospheric pressure drop caused by the tornado. Based on this justification, why is the request applicable to all actual or simulated emergency signals for the EDGs?
EMIB RAI #3 The LAR Section 3.0 includes a brief discussion of operator activities when an EDG is started. Please provide more specificity regarding the operator actions to monitor crankcase pressure during operation of the EDGs to provide assurance that timely operator action can be taken to avoid damage to each EDG from crankcase overpressure conditions.
Hearing Identifier: NRR_DRMA Email Number: 2228 Mail Envelope Properties (BY3PR09MB822593F3799F1F68196665EF94EEA)
Subject:
Fermi 2 - Request for Additional Information for License Amendment Request to Revise TS 3.8.1, AC Sources - Operating, Surveillance Requirement 3.8.1.12 (EPID L-2023-LLA-0069)
Sent Date: 9/7/2023 2:50:45 PM Received Date: 9/7/2023 2:50:00 PM From: Surinder Arora Created By: Surinder.Arora@nrc.gov Recipients:
"Roxanne Vonhabsburg" <roxanne.vonhabsburg@dteenergy.com>
Tracking Status: None "Jeff Whited" <Jeffrey.Whited@nrc.gov>
Tracking Status: None "Eric Frank" <eric.frank@dteenergy.com>
Tracking Status: None Post Office: BY3PR09MB8225.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 14088 9/7/2023 2:50:00 PM Options Priority: Normal Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: