ML070470267
| ML070470267 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 01/31/2007 |
| From: | Dacimo F Entergy Nuclear Northeast |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-06-002, NL-07-020 | |
| Download: ML070470267 (5) | |
Text
Entergy Nuclear Northeast Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Buchanan, NY 10511-0249 Tel 914 734 6700 Fred Daclmo Site Vice President Administration January 31, 2007 Re: Indian Point Units 2 & 3 Dockets 50-247 & 50-286 NL-07-020 Document Control Desk U.S. Nuclear Regulatory Commission Mail Stop O-Pl-17 Washington, DC 20555-0001
Subject:
Response to Request for Additional Information Regarding Resolution of Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power
References:
- 1. Request for Additional Information Regarding Resolution of Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power, dated December 5, 2006.
- 2. Revised Response Date for Request for Additional Information Regarding Resolution of Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power, dated December 13, 2006.
Dear Sir or Madam:
References 1 and 2 requested additional information regarding the resolution of Generic Letter 2006-02. Attachment 1 to this letter provides the responses to the requested information for Indian Point Units 2 and 3.
There are no new commitments identified in this letter. Should you or your staff have any questions regarding this submittal, please contact Mr. Patric W. Conroy, Manager, Licensing, at (914) 734-6668.
Very truly yours, Fred R. Dacimo Site Vice President Indian Point Energy Center
NL-07-020 Dockets 50-247 and 50-286 Page 2 of 2 : Response to Request for Additional Information Regarding Resolution of Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power cc:
Mr. Samuel J. Collins, Regional Administrator, Region 1 Mr. John Boska, NRR Senior Project Manager IPEC NRC Resident Inspector's Office, Indian Point Unit 2 IPEC NRC Resident Inspector's Office, Indian Point Unit 3 Mr. Paul Eddy, New York State Department of Public Service Mr. Peter R. Smith, President NYSERDA
Attachment I to NL-07-020 Response to Request for Additional Information Regarding Resolution of Generic Letter 2006-02, Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power ENTERGY NUCLEAR OPERATIONS, INC INDIAN POINT NUCLEAR GENERATING UNITS 2 and 3
NL-07-020 Dockets 50-247 and 50-286 Page 1 of 2 NRC Question:
- 3. Verification of RTCA Predicted Post-Trip Voltage Your response to question 2(g) indicates that you have not verified by procedure the voltages predicted by the online grid analysis tool (software program) with actual real plant trip voltage values. It is important that the programs used for predicting post-trip voltage be verified to be reasonably accurate and conservative. What is the range of accuracy for your GO's contingency analysis program? Why are you confident that the post-trip voltages calculated by the GO's contingency analysis program (that you are using to determine operability of the offsite power system) are reasonably accurate and conservative? What is your standard of acceptance?
Entergy Response:
The online grid analysis tool is not owned or operated by Entergy.
The Grid Operator (GO) Consolidated Edison, uses a state estimator and a contingency evaluation program to analyze real time and contingency voltage levels and thermal loading for the1 38kV system, which supplies IPEC's off-site sources.
The real-time contingency analysis program utilizes real-time transmission system information and nuclear generating unit specific shutdown loads and minimum voltage requirements. The program creates a model by combining real-time telemetry with the network model. The network model includes the nuclear power plant (NPP) facilities. The state estimator is then used to provide a consistent power flow that is used to run the contingencies. The contingency case assumes the simultaneous loss of the generator and the addition of load at the appropriate bus. An alarm is issued if the prescribed voltage limits are violated.
The GO uses the above real-time analysis tool, in conjunction with procedures, as the basis for determining when the 138kV system conditions warrant NPP notification.
The state estimator's on-line contingency analysis application utilized by the GO has been in service since 2005. Although there are no current industry standards that govern the accuracy of contingency analysis models, the GO uses the state estimator contingency analysis application at the 138 kV voltage level to support system operation.
North American Electric Reliability Corporation (NERC) has been established to ensure that the bulk electric system in North America is reliable, adequate and secure. Two of the responsibilities of NERC are:
" Set standards for the reliable operation and planning of the bulk electric system.
" Monitor, assess, and enforce compliance with reliability standards.
NERC has eight regional reliability councils whose members come from all segments of the electric industry and are responsible for overseeing and implementing the NERC criteria at the
NL-07-020 Dockets 50-247 and 50-286 Page 2 of 2 Regional Levels. Entergy's Indian Point Energy Center nuclear generators are located within the Northeast Power Coordinating Council's oversight area. Con Edison of NY Energy Control Center has overall responsibility for ensuring reliability of the 138kV transmission system supplying Indian Point Energy Center's off-site power source.
3a) What is the range of accuracy for your GO's contingency analysis program?
The accuracy of the state estimator and contingency analysis program is not specified.
There are two approved North American Electric Reliability Council Standards (IRO-002-1 "Reliability Coordination - Facilities" and TOP-006-1, "Monitoring System Condition"),
which establish the criteria the Reliability Coordinators and Transmission Operators shall follow to ensure an acceptable transmission system monitoring capability. Neither of these standards establishes an accuracy range for the system.
3b) Why are you confident that the post-trip voltages calculated by the GO's contingency analysis program (that you are using to determine operability of the offsite power system) are reasonably accurate and conservative?
The on-line contingency analysis system is one of the tools used by the GO to ensure the reliability of the bulk electric system by identifying system contingencies, which could result in unacceptable system conditions if the contingency were to occur.
In addition, prior to the present on-line contingency analysis system being placed into service in 2005, a number of typical post-contingency results were compared against the results of the power system simulator used for system planning by the GO. Based on the satisfactory results for this comparison process the on-line contingency analysis system was placed into service.
Our confidence in the accuracy of the on-line contingency analysis system is based on the inclusion of accurate nuclear plant specific accident shutdown loads provided by IPEC to the GO and the GO's operating experience in the use of the on-line contingency analysis system in identifying and responding to potential unacceptable bulk electric system conditions.
3c) What is your standard of acceptance?
As stated above, our confidence in the accuracy of the on-line contingency analysis system is based on the inclusion of accurate nuclear plant specific accident shutdown loads provided by IPEC to the GO and the GO's operating experience in the use of the on-line contingency analysis system in identifying and responding to potential unacceptable bulk electric system conditions.