NL-15-0433, Unit 2, Supplemental Response to Request for Additional Information from Mechanical and Civil Branch Regarding High Density Polyethylene (Hdpe) Piping Replacement RAI-13
| ML15069A640 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 03/05/2015 |
| From: | Pierce C Southern Co, Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-15-0433 | |
| Download: ML15069A640 (5) | |
Text
Charles R. Pierce Regulatory Affairs Director March 5, 2015 Docket Nos.: 50-366 Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 Fax 205.992.7601 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Unit 2 SOUTHERN A COMPANY NL-15-0433 Supplemental Response to Request for Additional Information from Mechanical and Civil Branch Regarding High Density Polyethylene (HOPE)
Piping Replacement RAI-13 Ladies and Gentlemen:
By letter dated February 19, 2015, Southern Nuclear Operating Company (SNC) responded to a Request for Additional Information (RAI) from the Nuclear Regulatory Commission (NRC) Mechanical and Civil Branch regarding proposed alternative HNP-ISI-AL T-HDPE-01, Version 2.0. This alternative requests authorization to replace buried steel Plant Service Water (PSW) piping with high density polyethylene (HOPE) piping. Based on subsequent discussion with the NRC staff, supplemental information is needed for SNC's response to RAI-13. to this letter provides the requested supplemental information.
This letter contains no NRC commitments. If you have any questions, please contact Ken McElroy at (205) 992-7369.
Respectfully ~tte.d, t.!{ ~
C. R. Pierce Regulatory Affairs Director CRP/RMJ
Enclosure:
U. S. Nuclear Regulatory Commission NL-15-0433 Page2 cc:
Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bost, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President-Hatch Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. D. R. Madison, Vice President-Fleet Operations Mr. B. J. Adams, Vice President-Engineering Mr. G. L. Johnson, Regulatory Affairs Manager - Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager - Hatch Mr. D. H. Hardage, Senior Resident Inspector-Hatch
Edwin I. Hatch Nuclear Plant - Unit 2 Supplemental Response to Request for Additional Information from Mechanical and Civil Branch Regarding High Density Polyethylene (HOPE)
Piping Replacement RAI-13 SNC Supplemental Response to NRC RAI to NL-15-0433 SNC Supplemental Response to NRC RAI By letter dated February 19, 2015, Southern Nuclear Operating Company (SNC) responded to a Request for Additional Information (RAI) from the Nuclear Regulatory Commission (NRC) Mechanical and Civil Branch regarding proposed alternative HNP-ISI-ALT-HDPE-01, Version 2.0. This alternative requests authorization to replace buried steel Plant Service Water (PSW) piping with high density polyethylene (HOPE) piping. Based on subsequent discussion with the NRC staff, additional clarification was needed regarding how safe shutdown capability is maintained if the Unit 2 Division II PSW valve pit flooded. Below is the additional clarification:
From Hatch Calculation SMNH-12-0020, "The PSW System consists of the ultimate heat sink (the Altamaha River) and two independent and redundant subsystems. Each of the two PSW subsystems is made up of a header, two 8500 gpm pumps, a suction source, valves, piping and associated instrumentation. For normal or emergency safe reactor shutdown either of the two subsystems is capable of providing the required cooling capacity to support the required systems with one pump operating. The two subsystems are separated from each other so failure of one subsystem will not affect the operability of the other system."
If the Unit 2 Division II existing PSW valve pit was to flood and cause all the equipment within the pit to be inoperable, safe shutdown could still be achieved through safe shutdown path 1 because there is no safe shutdown path 1 equipment within the Unit 2 Division II existing PSW valve pit.
If there was a loss of inventory from the Unit 2 Division II piping being replaced with HOPE, adequate cooling flow is capable of being provided by the redundant PSW subsystem (safe shutdown path 1) to achieve safe shutdown. The loss of inventory from the Unit 2 Division II piping does not impact the ability for the redundant PSW subsystem to provide adequate cooling flow.
There are existing conduit runs between the Unit 2 Division II and Division I PSW valve pits. The Unit 2 Division I PSW valve pit contains safe shutdown path 1 equipment. This design change will ensure these conduit runs are adequately sealed such that water from the Unit 2 Division II valve pit cannot reach the Unit 2 Division I valve pit to impact safe shutdown path 1 equipment.
Both Unit 2 PSW valve pits currently have 6-inch curbs around their perimeters that are designed to prevent the entrance of liquid combustibles from a large spill of fuel oil truck (Reference Hatch Fire Hazard Analysis, Fire Areas 2601 and 2602). If the Unit 2 Division II PSW valve pit was to flood and overflow into the yard area, the existing 6-inch curb will prevent the water from entering the Unit 2 Division I PSW valve pit.
In conclusion, if the new Unit 2 Division II PSW pit was to flood, safe shutdown could still be achieved through safe shutdown path 1 because E1-1 to NL-15-0433 SNC Supplemental Response to NRC RAI there will be no safe shutdown path 1 equipment in the new Unit 2 Division II PSW pit, the loss of inventory of the Division II piping will not impact safe shutdown path 1 inventory, and there will be no pathways for flood water in the new Unit 2 Division II PSW pit to reach safe shutdown path 1 equipment where it could potentially impact safe shutdown.
E1-2