NRC-14-0056, Comment (3) of Zackary W. Rad on Behalf of NEI on Draft Branch Technical Position (BTP) 8-9, Open Phase Conditions in Electric Power System, Docket Id NRC-2014-0131
| ML14205A007 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 07/21/2014 |
| From: | Rad Z DTE Energy |
| To: | Cindy Bladey Acquisition Management Division |
| References | |
| 79FR36580 00003, NRC-14-0056, NRC-2014-0131 | |
| Download: ML14205A007 (5) | |
Text
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DTE Energy Company 2014' ji 22 AM 10: 12 6400 North Dixie Highway Newport, MI 48166
, DTE Energy.
Docket ID:
NRC-2014-0131 July 21, 2014 NRC-14-0056 Cindy Bladey Office of Administration Mail Stop: 3WFN 03-44M U.S. Nuclear Regulatory Commission Washington D C 20555-0001
References:
- 1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43
- 2) NRC Draft Branch Technical Position, (BTP) 8-9, "Open Phase Conditions in Electric Power System," Docket ID NRC-2014-0131
Subject:
Comments on Draft Branch Technical Position (BTP) 8-9, "Open Phase Conditions in Electric Power System," Docket ID NRC-2014-0131 On June 5, 2014, the U.S. Nuclear Regulatory Commission (NRC) issued Draft Branch Technical Position, (BTP) 8-9, "Open Phase Conditions in Electric Power System," (Reference 2) for public comment via Federal Register Volume 79, Number 108 (79FR32580). DTE Electric Company (DTE) hereby submits the enclosed comments regarding the draft BTP.
Should you have any questions or require additional information, please contact me at (734) 586-5076.
Sincerely, q2ackary W. Rad Manager - Nuclear Licensing
Enclosure:
DTE Comments Regarding Draft BTP 8-9 SUNSI Review Complete Template = ADM - 013 E-RIDS= ADM-03 A dd = g-ý
USNRC NRC- 14-0056 Page 2 cc: NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Nuclear Energy Institute, Gordon Clefton
Enclosure to NRC-14-0056 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 DTE Comments Regarding Draft BTP 8-9 Docket ID NRC-2014-0131
Enclosure to NRC-14-0056 Page 1 DTE Comments Regarding Draft BTP 8-9 Comment 1 BTP Section A, para 6, sentence 2 states: "At Byron, both offsite and onsite electric power systems were not able to perform their intended safety functions due to the [OPC] design vulnerability."
BTP Section B. 1.V, "Protective Actions," states: "For an open phase condition, the staff finds the following method for meeting the design requirements acceptable:..."
Comment: The draft BTP is predicated on the assumption that all plants are similarly vulnerable to an Open Phase Condition (OPC), with resulting failures of both offsite power systems and onsite emergency generation systems; specifically, that an OPC on one of the two offsite power systems could result in the loss of capability of the alternate offsite power circuit and the onsite power system to restore power to safety related loads. This is not the case; e.g. see the Fermi 2 response to Bulletin 2012-01 (ML I2299A246). Fermi 2 has two independent, separate offsite Extra High Voltage (EHV) sources directly powering divisional Engineered Safety Features (ESF) buses (the Station Auxiliary Transformers are always loaded), Emergency Diesel Generators (EDGs) start on Design Basis Accident (DBA) signal, and transfer of loads between the offsite and onsite sources is direct and not dependent on intermediate Unit Auxiliary Transformer (UAT) and System Service Transformer (SST) bus transfer. An OPC on one offsite power source will not impact the availability of the other offsite power source or onsite emergency power.
ProposedResolution: The staff should not assume automatic OPC protection is required for GDC 17 compliance. The BTP should identify that other design configurations (i.e. other than the BTP specified designs for automated detection and actuation circuits) are acceptable, based on GDC 17 requirements.
Basis: GDC 17 offsite power requirements ("... power from the transmission network to the onsite electric distribution system shall be supplied by two physically independent ... to minimize to the extent practical the likelihood of their simultaneous failure..."), considering an OPC, are met by the configuration described above. This configuration also encompasses GDC 17 requirements that; "Provisions shall be included to minimize the probability of losing electric power from any of the remaining supplies as a result of, or coincident with, the loss of power generated by the nuclear power unit, the loss of power from the transmission network, or the loss of power from the onsite electric power supplies."
Comment 2 BTP Section B. 1.III "Circuit Classification," states, "Class IE detection and actuation circuits at the ESF bus level meet the applicable requirements of GDC 17..."
Comment: Class 1E detection and actuation circuits are not appropriate considering; 1) an OPC solution should be implemented on the high side of the transformer, and 2) the definition of Class 1E equipment infers requirements for separation from non-Class IE circuits.
Ehclosure to NRC- 14-0056 Page 2 DTE Comments Regarding Draft BTP 8-9 ProposedSolution: Eliminate discussion of Class IE solution.
Basis: Reliable detection of open phase requires the desired protection element to be measured on the high side of the transformer. This is supported by industry experts; e.g. Ferrer, H.J.A &
Schweitzer 1II, E.O., "Modem Solutions for Protection, Control, and Monitoring of Electric Power Systems," 1st Edition, 2010, section 4.12.2 states, "The relays on the line with the open phase can determine that the phase is open... However, the relays at other locations typically do not have information about the open-phase condition."
The draft BTP classification of 1E detection and actuation circuits would require measurement at ESF buses on the low side of the System Auxiliary Transformer (SAT) where typically there is no indication of the open-phase condition. The measured value (of unbalance voltage) on low side of the SAT is known to be influenced by many other factors and may bear no direct correlation with an open phase on the high side. The vendor solutions currently available are all high side non-Class 1E solutions. The proposed requirement for Class IE detection and actuation, if coupled with the requirement to separate Class 1E and non-Class 1E circuits, would prevent the adoption of the best practice in protective relaying whereby the most direct path and fastest time should be utilized to isolate the fault (e.g. OPC fault) and complete the consequential actions.
Comment 3 BTP Section B. 1. V(2)b states: "... The analyses should include all design and licensing basis assumptions including single failure criterion."
Comment: Single failure criterion is not applicable to the OPC analysis.
ProposedSolution: Eliminate "including single failure criterion."
Basis: GDC 17 requires onsite power analyses assuming single failure, but does not require offsite power analysis assuming single failure, as provided below from GDC 17 (emphasis added):
" "The onsite electric power supplies, including the batteries, and the onsite electric distribution system, shall have sufficient independence, redundancy, and testability to perform their safety functions assuming a single failure."
" "Electric power from the transmission network to the onsite electric distribution system shall be supplied by two physically independent circuits (not necessarily on separate rights of way) designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions."