L-MT-06-084, 2006 Report of Changes and Errors in ECCS Evaluation Models
| ML063630343 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 12/30/2006 |
| From: | Conway J Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-MT-06-084 | |
| Download: ML063630343 (4) | |
Text
Monticello Nuclear Generatina Plant Commitled to Nuclear Excellence Operated by Nuclear Management Company, LLC December 30,2006 L-MT-06-084 10 CFR 50.46(a)(3)
U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket 50-263 License No. DPR-22 2006 Report of Chanqes and Errors in ECCS Evaluation Models
References:
- 1) GE Report: NEDC-32514P, Revision 1, "Monticello SAFERIGESTR LOCA Loss of Coolant Accident Analysis," dated October 1997.
(Exhibit G to LAR, Revision I, Dated July 26, 1996, Supporting Monticello Nuclear Generating Plant Power Rerate Request Program.)
- 2) GE Report: GE-NE-J1103878-09-02P, "Monticello ECCS-LOCA Evaluation for GE14," GE Proprietary Information, dated August 2001.
- 3) NMC to NRC letter, "2005 Report of Changes and Errors in ECCS Evaluation Models," (L-MT-05-106), dated December 29, 2005.
- 4) GE 10 CFR 50.46 notification letter 2006-01, "Impact of Top Peaked Power Shape for Small Break LOCA Analysis," July 28, 2006.
Pursuant to 10 CFR 50.46(a)(3), Nuclear Management Company, LLC (NMC) is providing the annual report of changes or errors identified in the Emergency Core Cooling System (ECCS) evaluation models or application for the Monticello Nuclear Generating Plant (MNGP). This report is for the period between July 2005 and July 2006.
The MNGP Loss of Coolant Accident (LOCA) analyses of record (AOR) are contained in General Electric (GE) reports submitted for the MNGP rerate (Reference 1) and the LOCA analysis for the GE14 fuel type (Reference 2). Two GE fuel types are currently in use, the GEl I and GE14 fuel types.
During the period covered, one notification of a change or error resulting in a change to the calculated Peak Cladding Temperature (PCT) was received from GE. The change 2807 West County Road 75 Monticello, Minnesota 55362-9637 Telephone: 763.295.5151 Fax: 763.295.1454
USNRC Page 2 of 2 was to model small-break LOCA with a top-peaked power shape, rather than a mid-peaked power shape. When the change was made, the PCT for GE14 fuel increased by 30 O F, while the PCT for GEI 1 fuel was unaffected.
The current adjusted licensing basis PCTs for the fuel types in use at MNGP are:
Licensina Basis Fuel Tvpe PCT ( O F )
GEl I GE14 provides a summary table of the applicable changes and errors in the LOCA analyses from when the last analyses of record were performed.
This letter makes no new commitments or changes any existing commitments.
John T. ~onwav Site Vice president, Monticello Nuclear Generating Plant Nuclear Management Company, LLC Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Monticello Resident Inspector, Monticello Minnesota Department of Commerce
TABLE 1 -
SUMMARY
OF MONTICELLO LOCA CHANGES AND ERRORS INVOLVING CHANGES IN PEAK CLADDING TEMPERATURE (PCT)
Applicable Analysis or Error Description lmpact of SAFER Time Step Size on the PCT for Jet Pump Plant Analyses (Notification Letter 2000-04)
Monticello Loss of Coolant Accident (LOCA) Analyses of Record (AOR):
Ref.
NEDC-32514P, Rev 1, Monticello SAFERIGESTR-LOCA Loss of Coolant Accident Analysis GE-NE-J1103878-09-02P, Monticello ECCS-LOCA Evaluation for GE14 An inconsistent core exit steam flow was used in the SAFER pressure equation, resulting in premature termination of ECCS 1
Licensing Basis PCT (OF)
G E l l I GE14 The time step size used in the SAFER-LOCA code was determined inappropriate to achieve good numerical convergence for an accurate PCT.
lmpact of SAFER Pressure Rate Inconsistency Error on PCT (Notification Letter 2001 -02) condensation, and an increase in the second PCT.
SAFER Core Spray Injection Elevation Error (Notification 2
1 Letter 2002-01 )
I I
I 3
An error in the automation code that prepared input for SAFER resulted in the core spray sparger elevation being specified lower than actual.
lmpact of SAFER LevelNolume Table Error on PCT (Notification Letter 2003-01) 2087 Level and volume tables used by SAFER were not updated when a revised initial water level was implemented.
lmpact of Top Peaked Power Shape for Small Break LOCA Analysis (Notification Letter 2006-01) 4 9 6 0
-5 NIA NIA Small Break LOCA analyses had assumed a mid-peaked axial power shape consistent with the DBA break analysis. It was determined that a top-peaked axial power shape can result in Sum of absolute value of changes since last AOR.
7 90 1
45 I
I Algebraic sum of changes since last AOR.
30 0
50 1
+I5
+30 Sum of absolute value of changes during the current reporting period.
0
References
- 1.
GE Report: NEDC-32514P, Revision 1, "Monticello SAFERIGESTR-LOCA Loss-of-Coolant Accident Analysis," Dated October 1997. (This report is Exhibit G of Revision 1 to License Amendment Request Dated July 26, 1996, Supporting Monticello Nuclear Generating Plant Power Rerate Request Program.)
- 2.
GE Report: GE-NE-J1103878-09-02P, "Monticello ECCS-LOCA Evaluation for GE14," GE Proprietary Information, dated August 2001.
- 3.
10 CFR 50.46 Notification Letter 2000-04, "lmpact of SAFER Time Step Size on the Peak Clad Temperature (PCT) for Jet Pump Plant Analyses," dated November 8,2000.
- 4.
10 CFR 50.46 Notification Letter 2001-02, "lmpact of SAFER Pressure Rate Inconsistency Error on the Peak Clad Temperature (PCT)."
- 5.
10 CFR 50.46 Notification Letter 2002-01, "SAFER Core Spray Injection Elevation Error, GE Proprietary Information, dated June 13, 2002.
- 6.
10 CFR 50.46 Notification Letter 2003-01, "lmpact of SAFER LevelNolume Table Error on the Peak Clad Temperature (PCT), GE Proprietary Information, dated May 6,2003.
- 7.
10 CFR 50.46 Notification Letter 2006-01, "lmpact of Top Peaked Power Shape for Small Break LOCA Analysis," GE Proprietary Information, dated July 28, 2006.