ML060400198
| ML060400198 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 02/10/2006 |
| From: | Mahesh Chawla Plant Licensing Branch III-2 |
| To: | Nuclear Management Co |
| chawla M, NRR/DORL, 415-8371 | |
| References | |
| TAC MC9001, TAC MC9002 | |
| Download: ML060400198 (5) | |
Text
February 10, 2006 LICENSEE:
NUCLEAR MANAGEMENT COMPANY, LLC FACILITY:
Prairie Island Nuclear Generating Plant, Units 1 and 2
SUBJECT:
SUMMARY
OF FEBRUARY 1, 2006, MEETING WITH NUCLEAR MANAGEMENT COMPANY, LLC, ON EMERGENCY DIESEL GENERATORS (TAC NOS. MC9001 AND MC9002)
On February 1, 2006, a Category 1 public meeting was held between the Nuclear Regulatory Commission (NRC) and representatives of Nuclear Management Company, LLC at NRC Headquarters, One White Flint North, 11555 Rockville Pike, Rockville, Maryland. The purpose of the meeting was to discuss Extension of Completion Time Extension License Amendment Request (LAR) for Emergency Diesel Generators (EDGs) of Prairie Island Nuclear Generating Plant, Units 1 and 2. A list of attendees is provided as Enclosure 1.
The licensee presented information on the LAR via slides which can be found in Agencywide Documents Access and Management System (ADAMS) Accession No. ML060330170. The presentation was on a LAR submitted by the licensee on November 21, 2006, to extend the completion time for EDGs at Prairie Island Nuclear Generating Plant, Units 1 and 2, from 7 to 14 days. The existing technical specifications (TS) for the EDGs and the proposed changes were discussed in detail. The licensee described the design strengths of Prairie Island Electrical Distribution System, and also addressed the capabilities of EDGs during a station blackout event. The later half of the presentation consisted of probalistic risk assessment (PRA) and PRA Model description. PRA Model Updates, Completion Time Extension Analysis and the results of the analysis were discussed in further details.
The NRC staff presented/discussed/queried the licensee about the following:
Although the licensee provided clarification to some of the staff questions, a formal request for additional information is scheduled to be sent to the licensee by April 15, 2006.
- 1. The licensee was asked to provide the excess capacity of each EDG (that will be used as an alternate power source) beyond its normally available safe shutdown capability for the loss of offsite power (LOOP) condition. The excess capacity of the alternate power source should be sufficient to power LOOP loads of the inoperable EDG bus.
- 2. The licensee was also asked to add provision in the TS to include condition when the alternate AC source becomes inoperable during the extended allowed outage time (AOT).
- 3. The NRC staff stated that additional compensatory measures may be required for the proposed AOT.
- 4. The NRC staff asked for further clarification of their bus transfer schemes.
The licensee stated that fast bus transfer from auxiliary transformer to "start-up" transformer (not their designation) is for non-safety loads only (e.g., reactor coolant pumps feedwater pumps, and non-safety service water). The safety buses are normally tied to the grid from one of two sources connected to offsite power. If one of these experiences degraded voltage (and if the other one does not), the sequencer will do a "slow, dead bus transfer" to the alternate source. If neither has sufficient voltage, the diesel generators will start and load. There are some normally running pumps powered by the safety bus - charging, component cooling water (CCW) and safety-related service water. Some (e.g., CCW) will auto start by the sequencer after the bus transfer; others (e.g., charging) must be manually started.
- 5. The licensee stated that one of their open Facts and Observations from peer review involved their uncertainty analysis. When questioned, their PRA engineer stated the values provided in the LAR are point estimates.
- 6. The NRC staff asked the licensee whether their PRA models initiating events for both "site" and "unit" LOOP events. The licensee stated that their model only had the site LOOP initiating event. When NRC staff asked how they analyzed the LOOP data; the licensee stated that they culled out events that would only apply to a single unit at a multi-unit site.
- 7. When questioned, the licensee PRA engineer stated that the bus cross-tie human error probability was about 3E-3.
Members of the public were not in attendance. Public Meeting Feedback forms were not received.
Please direct any inquiries to me at 301-415-8371, or mlc@nrc.gov.
/RA/
Mahesh L. Chawla, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306
Enclosure:
List of Attendees cc w/encls: See next page The licensee stated that fast bus transfer from auxiliary transformer to "start-up" transformer (not their designation) is for non-safety loads only (e.g., reactor coolant pumps feedwater pumps, and non-safety service water). The safety buses are normally tied to the grid from one of two sources connected to offsite power. If one of these experiences degraded voltage (and if the other one does not), the sequencer will do a "slow, dead bus transfer" to the alternate source. If neither has sufficient voltage, the diesel generators will start and load. There are some normally running pumps powered by the safety bus - charging, component cooling water (CCW) and safety-related service water. Some (e.g., CCW) will auto start by the sequencer after the bus transfer; others (e.g., charging) must be manually started.
- 5. The licensee stated that one of their open Facts and Observations from peer review involved their uncertainty analysis. When questioned, their PRA engineer stated the values provided in the LAR are point estimates.
- 6. The NRC staff asked the licensee whether their PRA models initiating events for both "site" and "unit" LOOP events. The licensee stated that their model only had the site LOOP initiating event. When NRC staff asked how they analyzed the LOOP data; the licensee stated that they culled out events that would only apply to a single unit at a multi-unit site.
- 7. When questioned, the licensee PRA engineer stated that the bus cross-tie human error probability was about 3E-3.
Members of the public were not in attendance. Public Meeting Feedback forms were not received.
Please direct any inquiries to me at 301-415-8371, or mlc@nrc.gov.
/RA/
Mahesh L. Chawla, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-282 and 50-306
Enclosure:
List of Attendees cc w/encls: See next page DISTRIBUTION:
PUBLIC RidsNrrDorl (CHaney/CHolden/EHackett)
LPLIII-1 R/F RidsNrrPMMChawla RidsNrrDorlLple (TKobetz)
RidsNrrLATHarris RidsNrrPMMPadovan RidsAcrsAcnwMailCenter RidsOgcMailCenter LMrowca (NRR/ADRA/DRA/APL)
TMensha (NRR/PMAS)
OHopkins (NRR/ADRA/DRA/APL)
SLaur (NRR/ADRA/DRA/APL)
RClark (NRR/ADRO/DIRS/ITSB)
AHowe (NRR/ADRA/DRA/APL)
RidsRgn3MailCenter (GGrant)
OChopra (NRR/ADES/DE/EEEB)
PHabighorst, RIII DWeaver RJasinski JStrasma, RIII ADAMS Accession Number: ML060400198 OFFICE NRR/LPL3-1/PM NRR/LPL3-1/LA NRR/LPL3-1/BC (A)
NAME MChawla THarris TKobetz DATE 2/10/06 2/10/06 2/10/06 OFFICIAL RECORD COPY
Prairie Island Nuclear Generating Plant, Units 1 and 2 cc:
Jonathan Rogoff, Esquire Vice President, Counsel & Secretary Nuclear Management Company, LLC 700 First Street Hudson, WI 54016 Manager, Regulatory Affairs Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC 1717 Wakonade Drive East Welch, MN 55089 Manager - Environmental Protection Division Minnesota Attorney Generals Office 445 Minnesota St., Suite 900 St. Paul, MN 55101-2127 U.S. Nuclear Regulatory Commission Resident Inspector's Office 1719 Wakonade Drive East Welch, MN 55089-9642 Regional Administrator, Region III U.S. Nuclear Regulatory Commission Suite 210 2443 Warrenville Road Lisle, IL 60532-4351 Administrator Goodhue County Courthouse Box 408 Red Wing, MN 55066-0408 Commissioner Minnesota Department of Commerce 85 7th Place East, Suite 500 St. Paul, MN 55101-2198 Tribal Council Prairie Island Indian Community ATTN: Environmental Department 5636 Sturgeon Lake Road Welch, MN 55089 Nuclear Asset Manager Xcel Energy, Inc.
414 Nicollet Mall, R.S. 8 Minneapolis, MN 55401 Michael B. Sellman President and Chief Executive Officer Nuclear Management Company, LLC 700 First Street Hudson, MI 54016 Craig G. Anderson Senior Vice President, Group Operations Nuclear Management Company, LLC 700 First Street Hudson, WI 54016 Mr. Thomas J. Palmisano Site Vice President Prairie Island Nuclear Generating Plant Nuclear Management Company, LLC 1717 Wakonade Drive East Welch, MN 55089 November 2005
ENCLOSURE List of Attendees Nuclear Regulatory Commission Mahesh Chawla - Project Manager - NRR/DORL Tim Kobetz - Branch Chief - NRR/DORL Technical Reviewers:
Steven Laur - NRR/DRA Ogbonna Hopkins - NRR/DRA Robert Clark - NRR/DIPM Om Chopra - NRR/DE/EEEB Andrew Howe - NRR/DRA Nuclear Management Company Gabe Salamon - Fleet Licensing Manager Dale Vincent - Licensing Engineer Mike Johnson - Electrical Design Engineer Tom Asmus - Principal PRA Engineer Chris Mund - Design Engineering Manager