ML100670150
| ML100670150 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 03/05/2010 |
| From: | Costanzo C NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-08-001, NG-10-0144 | |
| Download: ML100670150 (2) | |
Text
March 5, 2010 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-001 Duane Arnold Energy Center Docket 50-331 License No. DPR-49 NEXTera M
ENERGY~
DUANE ARNOLD NG-I0-0144 10 CFR 50.54(1)
Subject:
Clarification of Information Previously Provided in Response to Generic Letter 2008-01
Reference:
Letter, R. Anderson (FPL Energy) to USNRC, "Nine-Month Response to NRC Generic Letter 2008-01, 'Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems'," NG-08-0777, dated October 13,2008.
During a recent internal assessment of the NextEra Energy Duane Arnold, LLC (hereafter NextEra Energy Duane Arnold) Generic Letter (GL) 2008-01 correspondence, we discovered that two (2) statements made in our nine month response to the GL (Reference) were incorrect.
While these errors do not have a significant implication for public health and safety or common-defense and security, we nonetheless strive to provide the Staff with complete and accurate information at all times. Consequently, we are revising the incorrect information at this time.
In the Enclosure to the referenced letter on page 6, we made the following statement regarding the relative elevations of the low pressure Emergency Core Cooling System (ECCS) pump discharge check valves relative to the water level in the Suppression Pool:
This is accomplished by having pump discharge check valves at an elevation below the Suppression Pool water level and the installation of a "keep fill" pump.
This information is completely accurate for both the "A" and "B" Core Spray pumps and the "C" and "D" Residual Heat Removal (RHR) System pumps. However, for the "A" and "B" RHR pumps, the elevation of these pump discharge check valves (centerline at 730 ft, 3 inches) is not below the nominal water level of the Suppression Pool (elevation 729 feet, 8.25 inches). Given that the nominal diameter of these check valves is 12 inches, the check valve and associated horizontal piping is above the elevation of the Suppression Pool water level.
NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, IA 52324
NG-10-0144 March 5,2010 Page 2 of2 The intent of the original statement in the Reference letter was to demonstrate that the combination of the physical design of this piping (i.e., elevation of the discharge piping relative to the normal water level in the Suppression Pool), coupled with the "keep fill" pump, maintains the discharge piping of the low pressure ECCS systems sufficiently full of water such that unacceptable gas voiding in this location is avoided. That conclusion remains true, even with this slightly higher elevation for these piping sections on the RHR pump discharge. The keep fill pump does assist in maintaining these sections of piping sufficiently filled with water. In addition, routine operation of the RHR system, such as during performance of Technical Specification (TS) Surveillance Requirement (SR) 3.5.1.4 and whenever RHR Suppression Pool Cooling mode is utilized, such as in support ofTS SR 3.5.1.5 and SR 3.5.3.3, serve to dynamically vent these piping sections. The subject piping sections are part of the flow path used in those operating configurations and the pump flow rate achieved during them is at least as large as that assumed in the accident analysis. This provides assurance that any potentially accumulated gas is dynamically vented to the Suppression Pool.
Also, during a review of the quality control paperwork documenting the ultrasonic testing (UT) examinations performed as part of the GL actions, we discovered that only 46 such examinations were actually performed in the field, not 47 as stated in the Reference letter on page 10 of the Enclosure. None ofthe originally planned examinations were missed; we merely miscounted the total and failed to detect that error prior to docketing the referenced response.
NextEra Energy Duane Arnold regrets these misstatements and fully acknowledges our regulatory requirement to provide complete and accurate information to the Staff. We sincerely apologize for any inconvenience this may cause the Staff.
This letter contains no new or revised commitments.
Please contact Steve Catron, Manager, Nuclear Licensing (319-851-7234) should you have any questions regarding this matter.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on March 5, 2010.
Christopher R. Costanzo Vice President, Duane Arnold Energy Center NextEra Energy Duane Arnold, LLC cc: Administrator, Region III, USNRC Project Manager, DAEC, USNRC Resident Inspector, DAEC, USNRC