ML18289B026
| ML18289B026 | |
| Person / Time | |
|---|---|
| Site: | 05200021 |
| Issue date: | 10/16/2018 |
| From: | NRC |
| To: | Mitsubishi Heavy Industries, Ltd |
| References | |
| Download: ML18289B026 (3) | |
Text
1 US-APWRRAIsPEm Resource From:
Wunder, George Sent:
Tuesday, October 16, 2018 2:56 PM To:
Tapia, Joseph; US-APWRRAIsPEm Resource
Subject:
REQUEST FOR ADDITIONAL INFORMATION Attachments:
RAI_9574 (002).docx Joe, Attached please find RAI Letter No. 1100. We request that you either respond to this letter within 30 days or request an extension.
Thanks, George
Hearing Identifier:
Mitsubishi_USAPWR_DCD_eRAI_Public Email Number:
171 Mail Envelope Properties (BN6PR09MB12499C7BDF0DDA02BEFCBB4AF9FE0)
Subject:
REQUEST FOR ADDITIONAL INFORMATION Sent Date:
10/16/2018 2:56:25 PM Received Date:
10/16/2018 2:56:35 PM From:
Wunder, George Created By:
George.Wunder@nrc.gov Recipients:
"Tapia, Joseph" <Joseph_Tapia@mnes-us.com>
Tracking Status: None "US-APWRRAIsPEm Resource" <US-APWRRAIsPEm.Resource@nrc.gov>
Tracking Status: None Post Office:
BN6PR09MB1249.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 196 10/16/2018 2:56:35 PM RAI_9574 (002).docx 27882 Options Priority:
Standard Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
Recipients Received:
Request for Additional Information 1100 Issue Date: 10/16/18 Application
Title:
US-APWR Design Certification - Docket Number 52-021 Operating Company: Mitsubishi Heavy Industries Docket No.52-021 Review Section: 08.02 - Offsite Power System Application Section:
QUESTIONS 08.02-19 10 CFR Part 50, Appendix A, General Design Criterion (GDC) 17, "Electric Power Systems," requires, in part, that an onsite electric power system and an offsite electric power system with adequate capacity and capability shall be provided to permit functioning of structures, systems, and components important to safety.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.
The staff has determined that the applicant, in response to Request for Additional Information (RAI) 1096-8266, Question 08.02-18, did not completely address detection and mitigation strategies as described in Branch Technical Position (BTP) 8-9, "Open Phase Conditions (OPC) in Electric Power System." Therefore, the staff requests that the applicant address the following in response to this RAI:
- a. Clarify whether the Combined License (COL) applicant will address the details of the specific design of OPC during the COL stage. If the applicant decides to address the conceptual design of OPC during the COL stage, please provide a COL Item in the Design Control Document (DCD), Tier 2, Table 1.8-2 and Section 8.2.4, "COL Information." If not, please provide the information stated below.
In response to RAI 1096-8266, the applicant stated the undervoltage detection system can detect all OPC on the secondary side of the unit auxilary transformer (UAT) and reserve auxilary transformer (RAT).
During an OPC, if the secondary side of the transformer is regenerating a lost phase, there will be no change in voltage magnitude that would actuate the undervoltage relays. However, there will be a change in the phase angle and the current on the secondary side of the transformer. Since the undervoltage relays will be incapable of detecting the loss of phase as a function of phase angle, clarify how the undervoltage detection system can detect all OPC on the secondary side of the UATs and RATs. Please discuss and/or provide simulations and analysis that demonstrates that the undervoltage detection system can perform this capability. Additionally, describe whether phase unbalance or negative-sequence relays will be used detect OPC. If so, provide description how it will be used to detect OPC.
- b. In response to RAI 1096-8266, the applicant stated that the non-safety related OPC system installed in the high side of the RAT was connected to the safety-related buses. Please clarify the isolation that exist between the non-safety related and safety-related system and indicate whether it will meet the guidance in RG 1.75 which endorses IEEE Std. 384-1992, and RG 1.32 which endorses IEEE Std. 308-2001.
The Class 1E equipment is protected from open phase conditions.
The staff is unclear on whether ITAAC Item 28 includes OPC detection, alarm, and monitoring in the control room since the design commitment, the Inspections, Tests, Analyses, or the Acceptance Criteria do not include language that includes these three OPC features. Please provide an explicit statement in ITAAC Item 28 that clarifies that OPC monitoring/detecting/alarming in the control room are verified by the ITAAC.