ML072200252
| ML072200252 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 07/25/2007 |
| From: | Jensen J Indiana Michigan Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| AEP:NRC:7331-04, TAC MD3161 | |
| Download: ML072200252 (7) | |
Text
a Indiana Michigan Power INDIANA Cook Nuclear Plant MICHIGAN One Cook Place OWER Bridgman, Ml 49106 POWROAERcom A unit ofAmerican Electric Power July 25, 2007 AEP:NRC:7331-04 10 CFR 50.90 Docket No.: 50-316 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-P 1-17 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. Electronic Transmission from P. S. Tam, NRC, to M. K. Scarpello, R. G. Vasey, and S. D. Simpson, I&M, "D.C. Cook:
Additional Draft RAI re. Proposed Amendment (TAC MD3161)," dated January 11, 2007 (ML070110441).
- 3. 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, Request for Additional Information (TAC No. MD3161),"
AEP:NRC:7331, dated April 20, 2007 (ML071220081).
- 4. Letter from P. S. Tam, NRC, to M. K. Nazar, "D. C. Cook Nuclear Plant, Unit 2 (DCCNP-2) - Request for Additional Information Re:
Proposed Amendment Involving Reactor Trip on Low Turbine Oil Pressure (TAC No. MD3161)," dated June 28, 2007 (ML071720219).
In Reference 1, Indiana Michigan Power Company (I&M) submitted a license amendment request to revise the allowable value of 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.
Reference 2 transmitted the Nuclear Regulatory Commission's (NRC's)
U. S. Nuclear Regulatory Commission AEP:NRC:7331-04 Page 2 requests for additional information (RAIs) regarding the license amendment request. In Reference 3, I&M responded to the RAIs. In Reference 4, the NRC transmitted additional RAIs. The attachnment to this letter provides I&M's response to the additional RAIs.
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, 0
1h N. Jensenn Site Vice President RV/rdw Attachrnent:
Reactor Trip on Low Turbine Control Oil Pressure License Amendment Request, Request for Additional Information c: J. L. Caldwell, NRC Region III K. D. Curry, AEP Ft. Wayne, w/o attachment J. T. King, MPSC MDEQ - WHMD/RPMWS NRC Resident Inspector P. S. Tam, NRC Washington, DC
U. S. Nuclear Regulatory Commission Page 3 AEP:NRC:7331-04 AFFIRMATION 1, 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 request 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 aretrue 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 2ýDAY 0
2007 My Commission Expires (I t.o 12D15
i i
- Attachment to A-EP:NRC:7331-04 Reactor Trip on Low Turbine Control Oil Pressure License Amendment Request Request for Additional Information In Reference 1, Indiana Michigan Power Company (I&M) submitted a license amendment request to revise the allowable value of the reactor trip on low turbine oil pressure function to greater than or equal to (_Ž) 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 (NRC's) requests for additional information (RAIs) regarding the license amendment request. In Reference 3, I&M responded to the RAIs.
In Reference 4, the NRC transmitted additional RAIs.
The RAIs transmitted by Reference 4 are focused on details involved in the calibration of the pressure switches that would initiate a reactor trip on low turbine oil pressure. It should be noted. that 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. Thus, there is no safety analysis limit associated with the trip setpoint.
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.
I&M's response to the Reference 4 RAIs is provided below.
NRC Request 1 The I&M response to NRC Request 2 states that out-of-tolerance is defined as "exceeding the band established around a desired value... " However, I&M has not defined how this band is established. Provide information that describes the uncertainty elements that are included in the out-of-tolerance band, the basis for their inclusion, and how the tolerance band is calculated.
I&M Response The as-left tolerance band, or calibration tolerance for the reactor trip on low turbine control pressure (a pressure switch calibration), is typically set equal to the manufacturer's reference accuracy.
This is common industry practice and requires that the component is left
Attachment to AEP:NRC:7331-04 Page 2 consistent with the manufacturer's perfonnance expectation. At the Donald C. Cook Nuclear Plant (CNP), this use of the manufacturer's reference accuracy is controlled by an instrument setpoint uncertainty engineering guide. The as-found tolerance (AFT) band, or the limit at which the pressure switch is determined to be out-of-tolerance, accounts for the expected deviation from the as-left condition with time. The AFT is impacted by drift, maintenance and test equipment (MTE) accuracy, and calibration accuracy.
AFT = square root of (DR 2 + (MTE + CA) 2) where:
DR = drift that may include both time dependant and non-time dependent effects MTE = maintenance and test equipment accuracy CA = calibration accuracy (tolerance), which typically equals the manufacturer's reference accuracy NRC Request 2 The I&M response to NRC Request 2 (first paragraph) discusses actions for anl as-found condition that exceeds the calibration tolerance. However, I&M' has not defined how the calibration tolerance is determined. Provide the information about the uncertainties included in the calibration tolerance band, basis for their inclusion, and how the band is calculated.
I&M Response The calibration tolerance is typically set equal to the manufacturer's reference accuracy as described in the CNP instrument setpoint uncertainty engineering guide. The manufacturer's reference accuracy represents the manufacturer's expectation of component performance.
NRC Request 3 The I&M response to NRC Request 2 (oon page 3 [Reference 3], first fidl paragraph) provides an example of Unit 1 calibration tolerance, but did not state that the same value has been used for Unit 2 also, and how it was determined. Provide the calibration tolerance band for Unit 2.
I&M Response The calibration tolerance for the Unit 1 Turbine Low Fluid Oil Pressure switches is based on plus or minus (+/-) 0.5 percent (%) setpoint, which is the CNP generic pressure switch setpoint tolerance when no specific performance criteria are available from the vendor.
As the pressure switch manufacturer and model number are expected to be the same for Unit 2 and
Attachment to AEP:NRC:7331-04 Page 3 the pressure setpoint is also expected to be the same, the calibration tolerance is calculated to be 0.5% of 800 psig, or +/- 4 psig.
NRC Request 4 The I&M response to NRC Request 2 (on page 3 [Reference 3], first fill paragraph) states that the out-of-tolerance evaluation "may include changes to the acceptance criteria, changes to the switch design or calibration method (including the setpoint value), or the replacement of poorly petforming components. " but did not provide anv detail on how the evaluation results are determined, who makes that determination, and how soon this evaluation is to be completed. Provide the missing informnation.
I&M Response These pressure switches have been determined to monitor a "critical parameter" because the allowable value for the control oil pressure is specified in CNP's technical specifications (one of the criteria for being included in the "critical parameters" list). When a component on the "critical parameters" list is to be calibrated, CNP's control of "critical parameters" procedure requires the initiation of a condition report if the device is found damaged or out of tolerance (OOT), i.e., the AFT has been exceeded.
This condition report is evaluated in accordance with the control of critical parameters procedure and requires an engineering evaluation using a form provided in the procedure.
On the first and any subsequent occurrence of an OOT, the assigned engineer must address potential operability or Maintenance Rule concerns. On two consecutive OOT occurrences, procedural requirements state that the evaluation must also include any explicit disposition by stating one of the following:
The component needs to be repaired The component needs to be replaced Explicit justification why nothing is wrong with the component This evaluation is reviewed and documented in the close-out of the condition report. The time to close the condition report is controlled by CNP's corrective action process.
Attachment to AEP:NRC:7331-04 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. Electronic Transmission from P. S. Tam, NRC, to M. K. Scarpello, R. G. Vasey, and S. D. Simpson, I&M, "D.C. Cook: Additional Draft P-*I re. Proposed Amendment (TAC No. MD3161)," dated January 11, 2007 (ML070110441).
- 3. 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, Request for Additional Information (TAC No. MD3161)," AEP:NRC:7331, dated April 20, 2007 (ML071220081).
- 4. Letter from P. S. Tam, NRC, to M. K. Nazar, "D. C. Cook Nuclear Plant, Unit 2 (DCCNP-2) - Request for Additional Information Re: Proposed Amendment Involving Reactor Trip on Low Turbine Oil Pressure (TAC No. MD3161)," dated June 28, 2007 (ML071720219).