ML043650388
| ML043650388 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/21/2004 |
| From: | William Holston Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NMP1L 1903 | |
| Download: ML043650388 (2) | |
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@ Constellation Energy P.O. Box 63 Nine Mile Point Nuclear Station Lycoming, New York 13093 December 21, 2004 NMP1L 1903 U.S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C. 20555
SUBJECT:
-Nine-Mile Point Unit Nos. -1 and 2 Docket Nos. 50-220 and 50-4 10 Facility Operating License Nos. DPR-63 and NPF-69 Report of Changes or Errors Discovered in the Current Acceptable Emergency Core Cooling System Evaluation Model Gentlemen:
Pursuant to 10CFR50.46(a)(3)(ii), this letter provides this year's annual report concerning changes to, or errors discovered in, the emergency core cooling system (ECCS) evaluation model used for Nine Mile Point Units 1 and 2 (NMP1 and NMP2). Last year's annual report was submitted on December 22, 2003. Since then, General Electric has reported one new change in the latest approved ECCS analysis, which affects the peak clad temperature (PCT) calculations.
Licensee Event Report 04-002, "Changes and Errors in the Methodology Used by General Electric and Global Nuclear Fuel to Demonstrate Compliance with Emergency Core Cooling System Performance Requirements," submitted by a letter dated July 12, 2004, specifically addressed this change for NMP 1.
The change consists of a postulated new heat source during the Loss of Coolant Accident (LOCA) event.This-heat-source-involves-the-recombination of hydrogen-and oxygef within the fuel bundle during the core heatup. The additional heat would raise the temperature of the steam heat sink in the bundle, resulting in a potential increase in the peak cladding temperature and local oxidation. This recombination is spontaneous at temperatures above approximately 900TF.
The hydrogen is generated by the steam-zirconium reaction during heatup. The oxygen enters the vessel either as a dissolved gas in the ECCS water or through the break when the vessel fully depressurizes and draws the containment noncondensible gases back into the vessel. The current LOCA evaluation models do not include this new heat source. An evaluation was performed which determined that the impact on PCT due to this change is 00F for NMP2 and 25TF for NMP1.
Page 2 NMP1L 1903 Based on the above, for NMP 1, the maximum increase in PCT due to changes or errors in the latest analysis is 40'F. For NMP2, the maximum increase in PCT is 00F. The sum of the absolute values of the effect on PCT of all changes or errors in the latest approved ECCS analysis is 40'F for NMPI and 50F for NMP2.
The maximum anticipated PCT during a LOCA remains less than 22000F for NMP 1 and NMP2.
The cumulative effect on PCT of changes and errors identified since the latest approved ECCS analysis remains less than 50'F for NMP1 and NMP2, and is, therefore, not significant according to the criterion stated in 10CFR50.46(a)(3)(i).
Sincerely William C. Holston Manager Engineering Services WCH/RF/jm cc:
Mr. S. J. Collins, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector Mr. P. S. Tam, Senior Project Manager, NRR (2 copies)