ML071980393
| ML071980393 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 07/06/2007 |
| From: | Jensen J Indiana Michigan Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| AEP:NRC-7331-02, TAC MD3161 | |
| Download: ML071980393 (7) | |
Text
z Indiana Michigan Power INDIANA Cook Nuclear Plant MICHIGAN One Cook Place Bridgman, MI 49106 POWER6 AEPcom A unit ofAmerican Electric Power July 6, 2007 AEP:NRC:7331-02 10 CFR 50.90 Docket No.: 50-316 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-Pl-17 Washington, DC 20555-0001 Donald C. Cook Nuclear Plant Unit 2 Technical Specification Change for Reactor Trip on Low Turbine Oil Pressure Request for Additional Information (TAC No. MD3161)
References:
- 1. Letter from J. N. Jensen, Indiana Michigan Power Company (I&M), to Nuclear Regulatory Commission (NRC) Document Control Desk, "Donald C. Cook Nuclear Plant Unit 2, Technical Specification Change for Reactor Trip on Low Turbine Oil Pressure," AEP:NRC:6331-02, dated September 15, 2006 (ML062690500).
- 2. Letter from P. S. Tam, NRC, to M. K. Nazar, I&M, "D. C. Cook Nuclear Plant Unit 2 (DCCNP-2) - Request for Additional Information Regarding Proposed Amendment Involving Turbine Control System Fluid Oil Pressure, (TAC No.
MD3161)," dated April 20, 2007 (ML071220081).
In Reference 1, Indiana Michigan Power Company (I&M) submitted a license amendment request to revise the Donald C. Cook Nuclear Plant Technical Specification 3.3.1, Table 3.3.1-1, Function 16.a Allowable Value for the reactor trip on low turbine oil pressure function to greater than or equal to
(-a) 750 pounds per square inch gauge (psig) from its current value of _57 psig because of a design change that replaces the present turbine control system with a control system that operates at a higher pressure. Reference 2 transmitted the Nuclear Regulatory Commission's requests for additional information (RAIs) regarding the license amendment request. The attachment to this letter provides I&M's response to the RAIs.
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U. S. Nuclear Regulatory Commission AEP:NRC:7331-02 Page 2 There are no new commitments made in this letter. Should you have any questions, please contact Ms. Susan D. Simpson, Regulatory Affairs Manager, at (269) 466-2428.
Sincerely, Site Vice President RV/rdw
Attachment:
Donald C. Cook Nuclear Plant Unit 2, License Amendment Request to Increase Reactor Trip on Low Turbine Control Oil Pressure Allowable Value, Request for Additional Information c: J. L. Caldwell, NRC Region III K. D. Curry, Ft. Wayne AEP, w/o attachment J. T. King, MPSC MDEQ - WHMD/RPMWS NRC Resident Inspector P. S. Tam, NRC Washington, DC
U. S. Nuclear Regulatory Commission AEP:NRC:7331-02 Page 3 AFFIRMATION I, Joseph N. Jensen, being duly sworn, state that I am Site Vice President of Indiana Michigan Power Company (I&M), that I am authorized to sign and file this document with the Nuclear Regulatory Commission on behalf of I&M, and that the statements made and the matters set forth herein pertaining to I&M are true and correct to the best of my knowledge, information, and belief.
Indiana Michigan Power Company Joseph N. Jensen Site Vice President SWORN TO AND SUBSCRIBED BEFORE ME THIS DAY OF - .AA , 2007 My Commission Expires UL\t1?-0:a
Attachment to AEP:NRC:7331-02 Donald C. Cook Nuclear Plant Unit 2 License Amendment Request to Increase Reactor Trip on Low Turbine Control Oil Pressure Allowable Value Request for Additional Information In Reference 1, Indiana Michigan Power Company (I&M) submitted a license amendment request to revise the Donald C. Cook Nuclear Plant Technical Specification (TS) 3.3.1, Table 3.3.1-1, Function 16.a Allowable Value for the reactor trip on low turbine oil pressure function to greater than or equal to (>) 750 pounds per square inch gauge (psig) from its current value of
> 57 psig because of a design change that replaces the present turbine control system with a control system that operates at a higher pressure.
The turbine control system is a non-safety-related system, and the reactor trip on low turbine oil pressure is not credited in any safety analyses. The reactor trip on low turbine oil pressure is an anticipatory trip that actuates shortly after a turbine trip to minimize the reactor pressure/temperature transient for a loss-of-load accident. The allowable value for the reactor trip on low turbine oil pressure has been chosen such that the actual trip setpoint, which is a nominal value, will be approximately one-half the control system's nominal operating pressure (the current Unit 2 allowable value is one-half the nominal operating pressure). The control system does not experience large pressure transients during normal operation, and the selection of an allowable value slightly less than one-half of the nominal operating pressure allows setting the trip setpoint at a value that prevents spurious trips that could result in challenges to safety systems.
Reference 2 transmitted the Nuclear Regulatory Commission's (NRC's) request for additional information regarding the license amendment request. The requested information is provided below.
NRC Request1 As indicatedin the licensee's submittal, the replacementof the turbine control system will increase the normal control oilfluid operatingpressurefrom 114 psig to 1600 psig and will revise the allowable low fluid oilpressure value for turbine tripfrom greaterthan or equal to 57 psig to greater than or equal to 750 psig. Please provide the following information:
Request 1, Item 1 Discuss to what extent this change involves any associatedpiping design changes that are necessaryto accommodate the increasedpressure.
Attachment to AEP:NRC:7331-02 Page 2 I&M Response to Request 1, Item 1 The design will replace all associated hydraulic piping from a new supply skid to all required components with new piping. The design will use schedule 80 stainless steel piping, which is capable of withstanding the 1600 psig system pressure, for supply piping and high pressure hose connections to the hydraulic actuators.
Request 1, Item 2 Discuss whether or not pipe failures associated with this change need to be considereddue to the large increasein turbine oil operatingpressure.
I&M Response to Request 1, Item 2 The electro hydraulic (EHC) piping contains hydraulic fluid, and a postulated break of these lines has not been assumed. There is no safety-related equipment that would be adversely impacted by a postulated break in the EHC piping. A pipe break in the hydraulic system would result in a hydraulic fluid spill in the turbine building and would trip the main turbine. However, the break would have little impact on the remainder of the facility. The pumping rate of the supply pumps is less than 50 gallons per minute with an open ended pipe at zero psig. The system operating temperature, approximately 120 degrees Fahrenheit, precludes any impacts due to thermal expansion or fluid vaporization.
Request 1. Item 3
[Ifpipingfailures need to be considered] Discuss to what extent any safety-related equipment needs to be protectedfrom the effects of these postulatedpipefailures.
I&M Response to Request 1, Item 3 No postulated pipe failures are associated with the design change (See response to Request 1, Item 2).
NRC Request 2 There is insufficient information in the applicationregardingthe replacement of the existing mechanical-hydrauliccontrol system for the main turbine and the east and west main feed-pump turbines with a Triconex TS3000 triple modular redundant control system. Pleasedescribe:
Attachment to AEP:NRC:7331-02 Page 3 Request 2, Item 1 The system design and how it operates, and how oil pressure varies with time duringnormalplant operation andfollowing a turbine trip.
I&M Response to Request 2, Item 1 The Triconex TS3000 system controls the operation of the main feedpump turbines and the main turbine, both of which are located in the turbine building. The hydraulic system, which provides motive force for the main feedpump turbine and main turbine valve actuators and trip blocks, contains three pressure switches that provide inputs to the reactor protection system. The circuitry associated with the pressure switches and the reactor protection system is independent of the control system.
The EHC is pressurized by a pump to a nominal steady state pressure of 1600 psig.
There are no significant pressure transients associated with the EHC operation.
Following a turbine trip, EHC header drain valves open, and the non-compressible hydraulic oil is drained from the header, and the control oil pressure drops below the proposed allowable value in miliseconds.
Request 2, Item 2 The basisfor how the 750 psig trip set point was established to assurethat spurious trips will not occur and safety functions will not be challenged, including uncertaintyconsiderations.
I&M Response to Request 2, Item 2 The safety analyses do not credit the operation of this function for core protection.
Thus, there is no associated analytical limit for the Low Fluid Oil Pressure allowable value.
The proposed TS Allowable Value (> 750 psig) represents a nominal value (approximately one-half of the nominal operating pressure) that ensures the operation of this anticipatory reactor trip function. The chosen TS Allowable Value includes consideration of the minimum required EHC pressure, the expected calibration tolerance and calibration frequency of the pressure switches, and the expected time-based (drift) pressure switch setpoint changes.
Attachment to AEP:NRC:7331-02 Page 4
References:
- 1. Letter from J. N. Jensen, I&M, to NRC Document Control Desk, "Donald C.
Cook Nuclear Plant Unit 2, Technical Specification Change for Reactor Trip on Low Turbine Oil Pressure," AEP:NRC:6331-02, dated September 15, 2006 (ML062690500).
- 2. Letter from P. S. Tam, NRC, to M. K. Nazar, I&M, "D. C. Cook Nuclear Plant Unit 2 (DCCNP-2) - Request for Additional Information Regarding Proposed Amendment Involving Turbine Control System Fluid Oil Pressure, (TAC No.
MD3161)," dated April 20, 2007 (ML071220081).