ML092720023
| ML092720023 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 10/02/2009 |
| From: | Goodwin C Plant Licensing Branch III |
| To: | Pardee C Exelon Nuclear |
| Goodwin, Cameron S, NRR/DORL, 415-3719 | |
| References | |
| TAC ME0994, TAC ME0995 | |
| Download: ML092720023 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 2, 2009 Mr. Charles G. Pardee President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555
SUBJECT:
LASALLE COUNTY STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION RELATED TO REQUEST FOR A LICENSE AMENDMENT TO TECHNICAL SPECIFICATION 3.5.1, "EMERGENCY CORE COOLING SYSTEMS (ECCS) OPERATING" (TAC NOS. ME0994 AND ME0995)
Dear Mr. Pardee:
By letter to the Nuclear Regulatory Commission (NRC) dated March 26, 2009 (Agencywide Documents Access and Management System Accession No. ML090861004), Exelon Generation Company, LLC submitted a request to revise Technical Specification 3.5.1, "Emergency Core Cooling Systems (ECCS) Operating," to delete the existing allowance associated with the Automatic Depressurization System accumulator backup compressed gas system that currently allows a completion time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to restore bottle pressure to ~
500 psig, for the LaSalle County Station, Units 1 and 2.
The NRC staff is reviewing your submittal and has determined that additional information is required to complete the review. The specific information requested is addressed in the enclosure to this letter. During a discussion with your staff on September 24, 2009, it was agreed that you would provide a response 30 days from the date of this letter.
The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-3719.
Sincerely, Cameron S. Goodwin, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-373 and 50-374
Enclosure:
Request for Additional Information cc w/encl: Distribution via ListServ
REQUEST FOR ADDITIONAL INFORMATION LASALLE COUNTY STATION, UNITS 1 AND 2 DOCKET NOS. 50-373 AND 50-374 In reviewing the Exelon Generation Company's (Exelon's) submittal dated March 26, 2009 (Agencywide Documents Access and Management System Accession No. ML090861004),
related to revising Technical Specification (TS) 3.5.1, "Emergency Core Cooling Systems (ECCS) Operating," to delete the existing allowance associated with the Automatic Depressurization System (ADS) accumulator backup compressed gas system that currently allows a completion time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to restore bottle pressure to ~ 500 psig, for the LaSalle County Station (LSCS), Units 1 and 2, the Nuclear Regulatory Commission (NRC) staff has determined that the following information is needed in order to complete its review:
- 1. Please clarify how the existing deficiency in the LSCS TS was first identified, as it relates to TS 3.5.1, concerning the common pneumatic supply utilized to support the Low-Low Setpoint (LLS) function of the Safety Relief Valves (SRVs) and the ADS function of the SRVs. Is there any precedence of similar deficiency that existed in other plants?
- 2. Out of the seven SRVs that utilizes the ADS function, how many are credited in the analysis-of-record for LSCS for the limiting loss-of-coolant accident (LOCA) for Peak Central Temperature (PCT).
- 3. In page 8 of Attachment 1 of the submittal, it is stated, "This event involves a specific loss-of-coolant accident (LOCA) inside the primary containment with a concurrent loss of offsite power and a random failure that results in the inoperability of one of the two ADS bottle banks." Please clarify the following:
- a. Is the above mentioned event the limiting LOCA for PCT, and the most limiting single-failure being the random failure that results in the inoperability of one of the two ADS bottle banks? If it is not, then describe the limiting LOCA with the most limiting single-failure for LSCS. Is the limiting LOCA a small or a large-break LOCA?
- b. Were there any other postulated transients or accidents which were impacted by the existing deficiency in the TS? If there were, then describe the events.
- 4. It was stated in the submittal that with the backup compressed gas system bottle pressure of > 500 psig, or the reserve bottle pressure of> 1100 psig, there is sufficient nitrogen available for any postulated event involving LLS actuation and a subsequent need for ADS. Please explain how these numeric values of minimum required pressure (500 psig for backup, and 1100 psig for reserve bottles), were determined to be sufficient pressure in order to perform its intended safety function.
- 5. In page 4 of Attachment 1 of the submittal, it is stated, "The safety-related portion, referred to as the ADS accumulator backup compressed gas system, maintains the ADS ENCLOSURE
- 2 accumulators pressurized following a loss of the normal non-safety related pneumatic supply." This statement implies that the backup compressed gas system is considered safety-grade. Since the reserve compressed gas system installed at LSCS will also perform safety-related function, please clarify whether that system will be maintained as safety-grade system. If not, then explain why not.
- 6. In page 4 of Attachment 1 of the submittal, it is stated, "A control room alarm is also annunciated for low pressure in the ADS nitrogen bottle banks supply headers to indicate that the pressure in a bottle bank is approaching the bottle change-out pressure." Please clarify whether low pressure in the reserve bottles can also be detected through control room alarm. If not, then explain why it is not necessary.
ML092720023 NRR-088 OFFICE LPL3-2/PM LPL3-2/LA LPL3-2/BC NAME CGoodwin THarris SCampbell DATE 10/2/09 10/1/09 10/2/09