ML16172A111
| ML16172A111 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, LaSalle  |
| Issue date: | 06/29/2016 |
| From: | Blake Purnell Plant Licensing Branch III |
| To: | Bryan Hanson Exelon Generation Co, Exelon Nuclear |
| Purnell B, NRR/DORL/LPLIII-2, 415-2020 | |
| References | |
| CAC MF7325, CAC MF7326, CAC MF7327, CAC MF7328, CAC MF7329, CAC MF7330 | |
| Download: ML16172A111 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555 June 29, 2016
SUBJECT:
DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3; LASALLE COUNTY STATION, UNITS 1AND2; AND QUAD CITIES NUCLEAR POWER STATION, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING LICENSE AMENDMENT REQUEST TO REVISE SECONDARY CONTAINMENT ACCESS OPENING REQUIREMENTS (CAC NOS. MF7325-MF7330)
Dear Mr. Hanson:
By application dated February 3, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16034A542), Exelon Generation Company, LLC (the licensee) submitted a request to revise Surveillance Requirement (SR) 3.6.4.1.2 for Dresden Nuclear Power Station, Units 2 and 3; LaSalle County Station, Units 1 and 2; and Quad Cities Nuclear Power Station, Units 1 and 2. The proposed change would revise SR 3.6.4.1.2 to provide an allowance for brief, inadvertent, simultaneous opening of redundant secondary containment access doors during normal entry and exit conditions.
The U.S. Nuclear Regulatory Commission has reviewed the application and determined that it needs additional information to complete its review. A response to the enclosed request for additional information is requested to be provided within 30 days from the date of this letter.
Should you have any questions, please contact me at 301-415-1380 or by email at blake.purnell@nrc.gov.
Sincerely, Blake Purnell, Project Manager Plant Licensing Branch 111-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos.
50-237, 50-249, 50-373, 50-374, 50-254, and 50-265
Enclosure:
Request for Additional Information cc w/encl: Distribution via Listserv
REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO REVISE REQUIREMENTS FOR SECONDARY CONTAINMENT ACCESS OPENINGS DRESDEN NUCLEAR POWER STATION. UNITS 2 AND 3 LASALLE COUNTY STATION. UNITS 1 AND 2 QUAD CITIES NUCLEAR POWER STATION. UNITS 1 AND 2 DOCKET NOS. 50-237. 50-249. 50-373. 50-374, 50-254, AND 50-265 By application dated February 3, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16034A542), Exelon Generation Company, LLC (the licensee) submitted a request to revise Surveillance Requirement (SR) 3.6.4.1.2 for Dresden Nuclear Power Station, Units 2 and 3 (Dresden); LaSalle County Station, Units 1 and 2 (LaSalle); and Quad Cities Nuclear Power Station, Units 1 and 2 (Quad Cities). The proposed change would revise SR 3.6.4.1.2 to provide an allowance for brief, inadvertent, simultaneous opening of redundant secondary containment access doors during normal entry and exit conditions.
The U.S. Nuclear Regulatory Commission (NRC) has reviewed the application and determined that the information below is needed to complete its review.
Background
The application provides a limited discussion of the engineered and administrative controls which will be used to ensure that simultaneous opening of the redundant secondary containment access doors will remain brief and infrequent. The application states that "interlocks may not be effective," but does not describe the use of interlocks at Dresden, LaSalle, and Quad Cities.
The applications states:
For inadvertent, simultaneous opening of the doors, the administrative controls involve the fact that both doors are under continuous control of the individuals accessing the doors, and that the doors are promptly closed following entry and exit, restoring the secondary containment boundary. The phrase "being used for entry and exit" in the proposed change ensures that the time both doors may be open simultaneously is limited to the time it takes to traverse through a door, which is insignificant.
The application further states:
If an accident should occur during the brief period that both doors could be open for entry and exit, and should that accident require secondary containment Enclosure
RAl-1 vacuum to be established by the SGT [standby gas treatment] system, it might not be possible for the SGT system to establish the required vacuum until the door is closed. However, the accident analyses assume only one SGT subsystem is in operation and the secondary containment is initially at atmospheric pressure. Therefore, the few seconds required to close at least one secondary containment door should not have any significant effect on the ability to establish secondary containment vacuum as assumed in the accident analysis.
Provide assurance that adequate engineered and administrative controls will be used at each facility to ensure that simultaneous opening of the redundant secondary containment access doors will remain brief and infrequent. Describe any internal reporting, documenting, monitoring and trending which will be performed to ensure the adequacy of these controls. Discuss any differences between the current controls and the planned controls following the proposed change.
RAl-2 Provide a quantitative comparison of the time with which both doors may be opened simultaneously to the margin in the secondary containment drawdown time assumed in the design-bases analysis for each facility. Explain how the functional capability of secondary containment and the SGT system will be maintained during brief, inadvertent, simultaneous opening of the inner and outer access doors.
- b FFICE LPL3-2/PM LPL3-2/LA SBPB/BC E
BPurnell SRohrer BDenni
- GEMiller 6/20/16 6/20/16 6/20/16 6/22/16