L-MT-05-075, Response to NRC Requests for Additional Information Regarding License Amendment Request Supporting 24-Month Fuel Cycles

Response to NRC Requests for Additional Information Regarding License Amendment Request Supporting 24-Month Fuel Cycles

ML051890051
Person / Time
Site:	Monticello
Issue date:	07/01/2005
From:	Thomas J. Palmisano Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-05-075, TAC MC3692
Download: ML051890051 (7)

Text

NMC e Committed to Nuclear~xel Monticello Nuclear Generatinq Plant Operated by Nuclear Management Company, LLC July 1, 2005 L-MT-05-075 10 CFR 50.90 US Nuclear Regulatory Commission Document Control Desk Washington DC, 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 License No. DPR-22 Response to NRC Requests for Additional Information Regarding License Amendment Reauest Su1portina 24-Month Fuel Cvcles (TAC No. MC3692)

Reference 1) Letter from NMC to NRC, uLicense Amendment Request to Support 24-Month Fuel Cycles," dated June 30, 2004 Reference 2) Letter from NRC to NMC, "Monticello Nuclear Generating Plant -

Request For Additional Information Related To Technical Specifications Change Request to Implement a 24-Month Fuel Cycle (TAC No. MC 3692)," dated January 26, 2005 Reference 3) Letter from NRC to NMC, "Monticello Nuclear Generating Plant -

Second Request for Additional Information Related To Technical Specifications Change Request to Implement a 24-Month Fuel Cycle (TAC No. MC 3692)," dated January 31, 2005 Reference 4) Letter from NMC to NRC, Response to NRC Requests for Additional Information Regarding License Amendment Request Supporting 24-Month Fuel Cycles (TAC No. MC3692)," dated March 3, 2005 Reference 5) Letter from NRC to NMC, "Monticello Nuclear Generating Plant - Third Request for Additional Information Related To Technical Specifications Change Request to Implement a 24-Month Fuel Cycle (TAC No. MC 3692)," dated June 10, 2005 Pursuant to and in accordance with the requirements of 10 CFR Part 50, Section 50.90, Nuclear Management Company, LLC (NMC) herein provides its response to the NRC's request for additional information regarding the License Amendment Request (LAR) supporting 24-month fuel cycles for Monticello Nuclear Generating Plant (MNGP).

2807 West County Road 75

• Monticello, Minnesota 55362-9637 Telephone: 763.295.5151

USNRC Page 2 Reference 1 proposed Technical Specifications changes to Appendix A of Operating License DPR-22, for the MNGP. The purpose of the LAR was to revise the MNGP Technical Specifications (TS) to support 24-month fuel cycles.

References 2 and 3 requested NMC to provide additional information in support of the LAR submitted by Reference 1.

Reference 4 provided NMC's response to the NRC's Requests for Additional Information (RAls), Reference 2 and 3.

Reference 5 provided NMC with the NRC's third RAI related to TS change request to implement a 24-month fuel cycle. provides the NMC response to the NRC's RAI (Reference 5) for the previously submitted LAR in support of 24-month fuel cycles at MNGP.

This letter makes the following new commitments:

• NMC commits to continue resetting Limiting Safety System Settings (LSSS) setpoints within the specified tolerances (as-left criteria) until the Technical Specification Task Force's TS change pertinent to instrument setpoints has been approved by the NRC and assessed for applicability to MNGP.

• NMC commits to assess applicability of the Technical Specification Task Force's TS change pertinent to instrument setpoints, when approved by the NRC, to determine whether changes to MNGP's licensing basis are necessary.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on July 1. 2005 Z aJ.Pal misano Site Vice President, Monticello Nuclear Generating Plant Nuclear Management Company, LLC Enclosure cc: Regional Administrator-l1l, NRC NRR Project Manager, NRC Sr. Resident Inspector, NRC Minnesota Department of Commerce

ENCLOSURE I LICENSE AMENDMENT REQUEST TO SUPPORT 24-MONTH FUEL CYCLES RESPONSE TO THIRD REQUEST FOR ADDITIONAL INFORMATION Pursuant to the requirements of 10 CFR Part 50, Section 50.90, Nuclear Management Company, LLC (NMC) submitted a License Amendment Request for the Monticello Nuclear Generating Plant (MNGP) by letter dated June 30, 2004. This License Amendment Request was submitted to request revisions to the MNGP Technical Specification (TS) in support of 24-Month Fuel Cycles.

The NRC provided NMC with a Request For Additional Information (RAI) dated June 3, 2005 (TAC No. MC3692), regarding the above License Amendment Request. Listed below are the NRC's requests for additional information followed by the NMC response.

NRC Request #1.a:

James A. Lyons (NRC) letter to Alex Marion (Nuclear Energy Institute) of March 31, 2005, (ADAMS Accession No. ML050870008) contains background information to determine the trip setpoints and allowable values of safety-related instrumentation. The letter contains a generic Revised Method 3 Request for Additional Information that also applies to the Method 2 setpoint determination process used at Monticello. Accordingly, please provide the following additional information.

Discuss how the methodology and controls you have in place ensure that the analytical limit (AL) associated with a limiting safety system setpoint (LSSS) will not be exceeded (the AL is a surrogate that ensures the safety limits will not be exceeded). Include in your discussion information on the controls you employ to ensure the trip setpoint established after completing periodic surveillances satisfies your methodology. If the controls are located in a document other than the technical specifications (TSs), discuss how those controls satisfy the requirements of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.36. Also, please propose a TS change for the LSSS being changed by the license amendment request to incorporate a footnote that states "The as-left instrument setting shall be returned to a setting within the tolerance band of the trip setpoint established to protect the safety limit."

NMC Response:

As previously stated in NMC's License Amendment Request dated June 30, 2004, (Reference 1) and in the response to the NRC's request for additional information dated March 3, 2005, (Reference 4), MNGP utilizes the General Electric Setpoint Methodology (NEDC-31336P-A). Therefore, neither the Method 3 nor the Method 2 setpoint determination process is used at MNGP.

Technical Specifications are required by 10 CFR 50.36 to contain limiting safety system setpoints (LSSS), which are defined by the regulation as "...settings for automatic protective devices...so chosen that automatic protective actions will correct the Page 1of 5

abnormal situation before a Safety Limit (SL) is exceeded." The Analytic Limit (AL) is the limit of the process variable at which a safety action is initiated, as established by the safety analysis, to ensure that a SL is not exceeded. Any automatic protection action that occurs on reaching the AL therefore ensures that the SL is not exceeded.

However, in practice, the actual settings for automatic protective devices must be chosen to be more conservative than the AL to account for instrument loop uncertainties related to the setting at which the automatic protective action would actually occur.

NMC utilizes the General Electric Setpoint Methodology (NEDC-31336P-A) for derivation of Allowable Values (AV) and nominal trip setpoints (NTSPs) for MNGP (References 1 and 4). The AVs are derived from the ALs. The difference between the AL and the AV allows for channel instrument accuracy, calibration accuracy, process measurement accuracy, and primary element accuracy. The margin between the AV and the NTSP allows for instrument drift that might occur during the established surveillance period. Two verifications are performed for the calculated NTSP. The first of these, the Spurious Trip Avoidance Test, evaluates the impact of the NTSP on plant availability. The second verification, the LER Avoidance Test, evaluates the probability of exceeding the Allowable Value due to instrument drift. These two verifications are statistical evaluations that provide additional assurance of the acceptability of the NTSP and may require changes to the NTSP. Use of these methods and verifications in establishing NTSPs and AVs provides the assurance that if the setpoint is found conservative with respect to the AV during surveillance testing, the instrumentation will provide the required trip function by the time the process reaches the AL for the applicable events.

During surveillance testing, finding the setpoint conservative relative to the AV ensures that the automatic protective action will correct the abnormal situation before a safety limit is exceeded. Resetting the setpoint within a specified tolerance around the trip setpoint also protects the safety limit: the ability to reset the setpoint represents continued confidence that the channel can perform its intended safety function. MNGP plant procedures require the trip setpoint to be left adjusted to a value within the trip setpoint tolerance band (as left criteria) established in accordance with the uncertainty assumptions stated in the setpoint methodology.

Calibration data that are outside of specified acceptance criteria must be dispositioned via the corrective action process in accordance with plant procedures. Engineering evaluation of data determined to be outside of the as-found or as-left tolerance bands is required consistent with plant commitments to the NRC in response to Inspection Report 50-263/90018.

The instrument set points and AVs in the MNGP TS are chosen such that automatic protective actions will correct the abnormal situation before a Safety Limit (SL) is exceeded, thereby satisfying the requirements of 10CFR50.36. Site surveillance and calibration procedures require instruments to be left within a specified setting tolerance after testing. Instruments found outside of the as-found tolerance or instruments that cannot be reset within the setting tolerance are reported and evaluated under the site corrective action process. This evaluation,.which includes prompt operability evaluation consistent with the guidance of Generic Letter 91-18, provides a vehicle to verify that the device will protect the applicable SL and function as required. In this way, Page 2 of 5

instrument health is monitored so that degraded performance may be identified and evaluated in a timely fashion.

Current MNGP processes meet the intent of this request by the NRC staff for a proposed TS change. NMC will continue resetting LSSS setpoints within the specified tolerances (as-left criteria) until the Technical Specification Task Force's TS change pertinent to instrument setpoints has been finalized and assessed for applicability for MNGP. Therefore, NMC is not proposing any TS changes to address reset criteria for

[SSS instrumentation at this time. However, NMC commits to assess applicability of the Technical Specification Task Force's TS change pertinent to instrument setpoints, when finalized, to determine whether changes to MNGP's licensing basis are necessary.

NRC Request #1.b:

Discuss how the TS surveillances ensure the operability of the instrument channel. This should include a discussion on how the surveillance test results relate to the TS AL and describe how these are used to determine the operability of the instrument channel. if the requirements for determining operability of the LSSS instrument being tested are in a document other than the TS (e.g., plant test procedure), discuss how this meets the requirements of 10 CFR 50.36. Also, please provide an explicit regulatory commitment to assess the operability of tested instrumentation based on the previous as-left instrument setting and accounting for the uncertainties associated with the test or calibration.

NMC Response:

MNGP TS contain values related to the operability of equipment required for.safe operation of the facility. Operable is defined in TS as "...being capable of performing its specified function(s)." For automatic protective devices, the required safety function is to ensure that a Safety Limit is not exceeded and therefore the LSSS as defined by 10 CFR 50.36 is the same as the operability limit for these devices. The Allowable Valuable (AV) serves as the LSSS such that a channel is operable if the trip setpoint is found not to exceed the AV.

The AV designates the point beyond which an instrument may not be able to perform its required safety function due, for example, to greater than expected drift. This value is specified in order to define operability. The instrument is considered to be operable if it does not exceed the calculated AV.

An automatic protective device with an "as found" setting different from the NTSP due to drift may still be operable since some drift is expected. This expected drift is accounted for in establishing the NTSP, AV and As-Found (AF) tolerance for the device; thus, the protective action would still ensure the SL was not exceeded with the "as found" condition of the instrument if it did not exceed the AV or calculated AF tolerance.

Surveillance calibrations ensure instrument operability by determining the actual setting of the device relative to a specified tolerance value, which is no less conservative than the AV. If the actual setting of the device were found to have exceeded the AV the Page 3 of 5

device would be considered inoperable from a TS perspective. This requires corrective action including those actions required by 10 CFR 50.36 when automatic protective devices do not function as required.

In accordance with MNGP procedures, instruments found outside of the as-found tolerance or instruments that cannot be reset within the setting tolerance are reported and evaluated under the site corrective action process. In this way, instrument health is monitored so that degraded performance may be identified and evaluated in a timely fashion.

Additionally, the current corrective action process requires a Senior Reactor Operator (SRO) review of a condition when it affects plant operation or plant equipment. The SRO review includes a prompt operability determination. Corrective action items identifying instruments outside of specified tolerances affect plant equipment and are, therefore, subject to this SRO review. This practice assures that the operability status of plant equipment is assessed in a timely fashion.

NRC staff has stated that periodic surveillance testing or calibration of automatic protective system instrumentation must demonstrate that the performance of the device is within the expected range, accounting for uncertainties associated with the test or calibration. This may be achieved by assessing the operability of tested instrumentation based on the previous as-left instrument setting and accounting for the uncertainties associated with the test or calibration. Additional methods for evaluating whether instrumentation is performing in the expected range have been proposed and are currently being discussed within the industry and NRC. The NMC belives that it would not be prudent, at this time, to commit to a prescribed approach for operability assessment of LSSS instrumentation based on previous as left settings. However, NMC commits to assess applicability of the Technical Specification Task Force's TS change pertinent to instrument setpoints, when approved by the NRC, to determine whether changes to MNGP's licensing basis are necessary.

NRC Request #2:

Please provide an explicit regulatory commitment to assess applicability of the Technical Specification Task Force's TS change to determine whether changes to Monticello's licensing basis are necessary to come into conformance with the existing understanding of the requirements of 10 CFR 50.36.

NMC Response:

The NMC has reviewed recent NRC and industry meeting summaries (NEI Summary of NRC/NEI Meeting, June 2, 2005 - Instrument Setpoints) and correspondence (Alex Marion, NEI to Mr. James E. Lyons, NRC, "

SUBJECT:

Instrumentation, Systems, and Automation Society S67.04 Methods for Determining Trip Setpoints and Allowable Values for Safety-Related Instrumentation, dated May 18, 2005) on this topic. It is apparent that further discussions are necessary before a conclusion of industry non-compliance with the requirements of 10 CFR 50.36 can be reached and resolution of the associated technical issues achieved. Therefore, NMC has concluded that it would Page 4 of 5

be premature to commit to a course of action that is still under review by the industry and the NRC.

However, NMC commits to assess applicability of the Technical Specification Task Force's TS change pertinent to instrument setpoints, when approved by the NRC, to determine whether changes to MNGP's licensing basis are necessary.

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