L-MT-14-101, Annual Report of Changes in Emergency Core Cooling System Evaluation Models Pursuant to 10 CFR 50.46

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Annual Report of Changes in Emergency Core Cooling System Evaluation Models Pursuant to 10 CFR 50.46
ML14365A128
Person / Time
Site: Monticello Xcel Energy icon.png
Issue date: 12/30/2014
From: Fili K
Northern States Power Co, Xcel Energy
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-14-101
Download: ML14365A128 (6)


Text

Xcel Energy Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362 December 30, 2014 L-MT-14-1 01 10 CFR 50.46(a)(3)(ii)

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License No. DPR-22 2014 Annual Report of Changes in Emergency Core Cooling System Evaluation Models Pursuant to 10 CFR 50.46

Reference:

1) NRC to NSPM, "Monticello Nuclear Generating Plant-Issuance of Amendment No. 176 to Renewed Facility Operating License Regarding Extended Power Uprate (TAC No. MD9990)," dated December 9, 2013.
2) NRC to NSPM, "Monticello Nuclear Generating Plant-Issuance of Amendment No. 180 to Renewed Facility Operating License Regarding Maximum Extended Load Line Limit Analysis Plus (TAC No. ME3145),"

dated March 28, 2014.

3) NSPM to NRC, "June 2014, Thirty-Day Report of Changes in Emergency Core Cooling System Evaluation Models Pursuant to 10 CFR 50.46,"

(L-MT-14-054) dated June 17, 2014.

4) NSPM to NRC, "Report of Changes in Emergency Core Cooling System Evaluation Models," (L-MT-14-004) dated January 10, 2014.

Pursuant to 10 CFR 50.46(a)(3)(ii), the Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, is providing this annual report concerning changes/errors identified in the Emergency Core Cooling System (ECCS) evaluation models for the Monticello Nuclear Generating Plant (MNGP). The MNGP Loss of Coolant Accident (LOCA) analyses of record (AOR) are contained in the General Electric Hitachi (GEH) reports submitted for the MNGP Extended Power Up rate and the Maximum Extended Load Line Limit Analysis Plus (MELLLA+) license amendments (Reference 1 and 2).

A 30-day report was completed in June 2014 due to the issuance of several GEH Nuclear Energy 10 CFR 50.46 Notification Letters (Reference 3). The changes/errors discussed within those notification letters resulted in a cumulative increase in Peak Cladding Temperature (PCT) that exceeds the 50°F reporting threshold of 10 CFR 50.46(a)(3)(i), and hence, were reported in accordance with the regulation. There are

Document Control Desk L-MT-14-101 Page 2 of 2 no new notifications of changes or errors from GEH since submittal of the 30-day report sent in June of 2014. The nature of these changes/errors and their effect on PCT is summarized in Table 1 of Enclosure 1. These changes result in an adjusted PCT increase from the previously reported 2150°F (Reference 4) to 2170°F.

As prescribed by the regulation a proposed reanalysis schedule or an evaluation is needed to demonstrate the facility remains in compliance with 10 CFR 50.46 requirements. In accordance with 10 CFR 50.46(a)(3)(ii) the following evaluation is provided. The adjusted PCT is 30°F below the 2200°F acceptance criterion of 10 CFR 50.46(b)(1 ). This provides sufficient margin to justify taking no further actions. No further reanalysis or other actions are planned. provided additional information on the nature of the changes and their effect on the MNGP LOCA analysis. This information is being submitted in accordance with the requirement of 10 CFR 50.46(a)(3)(ii) for the MNGP.

If you have any question regarding this request, please contact Mr. Stephen Sollom at (763) 295-1611.

Summary of Commitments This letter makes no new commitments or changes any existing commitments.

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Karen D. Fili Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure cc: Regional Administrator, Region Ill, USNRC Project Manager, Monticello Nuclear Generating Plant, USNRC Resident Inspector, Monticello Nuclear Generating Plant, USNRC

ENCLOSURE 1 MONTICELLO NUCLEAR GENERATING PLANT TABLE 1 -

SUMMARY

OF MONTICELLO LOCA CHANGES AND ERRORS INVOLVING CHANGES IN PEAK CLADDING TEMPERATURE Page 1 of 3 TABLE 1-

SUMMARY

OF MONTICELLO LOCA CHANGES AND ERRORS INVOLVING CHANGES IN PEAK CLADDING TEMPERATURE (PCT)

Licensing Basis Applicable Analysis or Error/Change Description Ref.

PCT(°F)

GE14 NEDC-33322P, Revision 3, Safety Analysis Report for Monticello 1 &2 <2140 Constant Pressure Power Uprate PRIME Fuel Properties Implementation for Fuel Rod T/M Performance, replacing GESTR Fuel Properties (1 0 CFR 50.46 Notification Letter 2012-01, Revision 1)

This change is due to the application of an NRC-approved 3 +10 procedure to estimate the change in Peak Clad Temperature (PCT) due to the change in fuel properties from GESTR to PRIME primarily to address inaccuracies in fuel pellet thermal conductivity as a function of exposure.

SAFER04A E4-Maintenance Update Changes (1 0 CFR 50.46 Notification Letter 2014-01)

This change is for a new version (E4) of SAFER04A that 4 +0 resolves several accumulated observations that are code maintenance items. Sensitivity calculations show these items have an insignificant effect on calculated PCT.

SAFER04A E4-Mass Non-Conservatism (1 0 CFR 50.46 Notification Letter 2014-02)

This change is due to a logic error that occurs when upper plenum liquid mass and core spray flow rate are low. System 5 +15 mass is gradually lost due to core spray being discarded, resulting in marginally less ECCS flow credited as reaching the core.

SAFER04A E4-Minimum Core DP Model (1 0 CFR 50.46 Notification Letter 2014-03)

This change is due to the use of a minimum ~P that could be 6 +20 non-conservative offering inappropriate steam cooling benefit above the core two-phase level.

Page 2 of 3 TABLE 1-

SUMMARY

OF MONTICELLO LOCA CHANGES AND ERRORS INVOLVING CHANGES IN PEAK CLADDING TEMPERATURE (PCT)

Licensing Basis Applicable Analysis or Error/Change Description Ref.

PCT(°F)

GE14 SAFER04A E4-Bundle/Lower Plenum CCFL Head (1 0 CFR 50.46 Notification Letter 2014-04)

This change is due to the counter current flow limitation (CCFL) 7 -15 calculation representing the pressure head slightly different from that of the calculated water level in the bundle.

Sum of absolute value of changes for the current reporting period, which includes all changes since the 10 CFR 50.46 report in Reference 8. 60 Sum of absolute value of changes since last AOR (Reference 1). 60 Algebraic sum of changes for the current reporting period, which includes all changes since the 10 CFR 50.46 report in Reference 8. +30 Algebraic sum of changes since last AOR (Reference 1). +30 Current Adjusted Peak Cladding Temperature <2170 References

1. GE Report: NEDC-33322P, Revision 3, "Safety Analysis Report for Monticello Constant Pressure Power Uprate," dated October 2008 (Enclosure 5 of L-MT 052, dated November 5, 2008, ADAMS Accession No. ML083230111)
2. NSPM letter to NRC, "Monticello Extended Power Uprate and Maximum Extended Load Line Limit Analysis Plus License Amendment Requests: Supplement for Analytical Methods Used to Address Thermal Conductivity Degradation and Analytical Methods Limitations (TAC Nos. MD9990 and ME3145)," L-MT-13-053 dated July 8, 2013 (ADAMS Accession No. ML13191A568).
3. GEH 10 CFR 50.46 Notification Letter 2012-01, Revision 1, "PRIME Fuel Properties Implementation for Fuel Rod T/M Performance, replacing GESTR Fuel Properties," dated July 30, 2013.
4. GEH 10 CFR 50.46 Notification Letter 2014-01, "SAFER04A E4-Maintenance Update Changes," dated May 21, 2014.
5. GEH 10 CFR 50.46 Notification Letter 2014-02, "SAFER04A E4-Mass Non-Conservatism," dated May 21, 2014.
6. GEH 10 CFR 50.46 Notification Letter 2014-03, "SAFER04A E4-Minimum Core DP Model," dated May 21, 2014.

Page 3 of 3 TABLE 1 -

SUMMARY

OF MONTICELLO LOCA CHANGES AND ERRORS INVOLVING CHANGES IN PEAK CLADDING TEMPERATURE (PCT)

7. GEH 10 CFR 50.46 Notification Letter 2014-04, "SAFER04A E4-Bundle/ Lower Plenum CCFL Head," dated May 21, 2014.
8. L-MT-14-004, letter from K. Fili (NSPM) to NRC "Report of Changes in Emergency Core Cooling System Evaluation Models" dated January 10, 2014