ML110130480
| ML110130480 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 01/12/2011 |
| From: | Becker J R Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| DCL-11-001 | |
| Download: ML110130480 (14) | |
Text
Pacific Gas and Electric Company January 12, 2011 PG&E Letter DCL-11-001 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 James R. Becker Site Vice President Diablo Canyon Power Plant Mail Code 104/5/601
- p. O. Box 56 Avila Beach, CA 93424 805.545.3462 Internal:
691.3462 Fax: 805.545.6445 Response to Telephone Conference Call Held on December 14, 2010, Between U.S. Nuclear Regulatory Commission and Pacific Gas & Electric Company Concerning Responses to Requests for Additional Information Related to the Diablo Canyon Nuclear Power Plant. Units 1 and 2, License Renewal Application Dear Commissioners and Staff: By letter dated November 23, 2009, Pacific Gas and Electric Company (PG&E) submitted an application to the U.S. Nuclear Regulatory Commission (NRC) for the renewal of Facility Operating Licenses DPR-80 and DPR-82, for Diablo Canyon Power Plant Units 1 and 2, respectively.
The application included the license renewal application (LRA) and Applicant's Environmental Report -Operating License Renewal Stage. On December 14, 2010, a telephone conference between the NRC and representatives of PG&E was held to obtain clarification on PG&E's response to requests for additional information (RAI) submitted to the NRC in letters dated October 12, October 15, and November 8, 2010, regarding scoping and screening.
PG&E's supplemental information to the RAI responses is provided in Enclosure
- 1. PG&E amends commitments in revised LRA Table A4-1, License Renewal Commitments, shown in Enclosure 2-. LRA Amendment 37 is included in Enclosure 2 showing the changed pages with line-in/line-out annotations.
If you have any questions regarding this response, please contact Mr. Terence L. Grebel, License Renewal Project Manager, at (805) 545-4160.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway.
Comanche Peak. Diablo 'Canyon. Palo Verde. San Onofre. South Texas Project
- Wolf Creek Document Control Desk January 12, 2011 Page 2 PG&E Letter DCL-11-001 I declare under penalty of perjury that the foregoing is true and correct. Executed on January 12, 2011. Site Vice President TLG/50367168 Enclosures cc: Diablo Distribution celene: Elmo E. Collins, NRC Region IV Regional Administrator Nathanial B. Ferrer, NRC Project Manager, License Renewal Kimberly J. Green, NRC Project Manager, License Renewal Michael S. Peck, NRC Senior Resident Inspector Alan B. Wang, NRC Licensing Project Manger A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway.
Comanche Peak. Diablo Canyon. Palo Verde. San Onofre. South Texas Project. Wolf Creek PG&E Letter DCL-11-001 Page 1 of 6 PG&E Supplements to Telephone Conference Call Held on December 14, 2010, Concerning Responses to Requests for Additional Information (RAI) Submitted to the NRC in Letters Dated October 12, October 15 and November 8, 2010, Regarding Scoping and Screening RAI 2.1-1 In a telephone conference call held on December 14, 2010, the NRC requested additional information in regards to the spatial interaction of non-safety related fluid-filled components and the control room pressurization system (CRPS) supply fans, controls and instrumentation. In addition, the NRC requested additional information on the capability of fluid entering HVAC supply and exhaust ducting for the vital 480V switchgear rooms.
PG&E agreed to supplement the response to RAI 2.1-1.
PG&E Letter DCL-10-132, dated October 12, 2010, provided additional information on nonsafety-related piping in the turbine build ing that could fail and interact with any safety-related structures, systems and co mponents (SSC) in a manner that would prevent the performance of the system safety function for which the safety-related SSC is required.
A confirmatory walk-down was performed fo r the control room pressurization system (CRPS) supply fans and instrumentation and controls (I&C) for potential spatial interaction with nonsafety-related fluid-filled components. Firewater piping was identified approximately 60 ft to the nor th and east of the Unit 2 CRPS I&C and approximately 50 ft to the east of the Unit 1 CRPS I&C. These are the only fluid-filled components in the area and line-of-sight of the CRPS I&C cabinet. Nonsafety-related firewater piping in the vicinity of the CR PS supply fans, I&C on both Units is added to the scope of license renewal under 10 CFR 54.4(a)(2). License Renewal Application (LRA) Tables 2.3.3-12 and 3.3.2-12 are amended to reflect this change in Enclosure 2.
Boundary drawings LR-DCPP-18-106718-07 and LR-DCPP-18-106718-09 have been revised to include the additional in-scope SSCs.
A confirmatory walk-down was performed on t he heating, ventilation and air conditioning (HVAC) openings on the turbine deck, which s upply the 4160V switchgear rooms. On both Units 1 and 2, there is nons afety-related firewater piping in the vicinity of these openings. Nonsafety-related firewater piping in the vicinity of the 4160V ventilation exhaust openings on the turbine deck on both Units is added to the scope of license
renewal under 10 CFR 54.4(a)(2). LRA T ables 2.3.3-12 and 3.3.
2-12 are amended to reflect this change. Boundary drawi ng LR-DCPP-18-106718-09 has been revised to include the additional in-scope SSCs. Additi onally, there is a low pressure domestic PG&E Letter DCL-11-001 Page 2 of 6 water line supplying the temporary instrument repair shop on the Unit 1 side. Domestic water piping in the vicinity of the 4160V ventilation exhaust openings on the turbine deck on Unit 1 is added to the scope of license r enewal under 10 CFR 54.4(a)(2). The LRA is unaffected by this addition. B oundary drawing LR-DCPP-16-106718-21 has been revised to include the additional in scope SSCs.
A confirmatory walk-down was performed on the HVAC supply and exhaust ducting
which feeds the vital 480V switchgear room.
Rainwater cannot enter the HVAC supply ducting on either unit. The supply ducts hav e louvers tilted downwards on the entrance precluding rain from entering. Similarly, rain cannot enter the Unit 1 exhaust ducting since the exit is oriented downwards. T he Unit 2 exhaust ducting exit is oriented upwards. The Unit 2 exhaust ductwork has prov isions to allow water to drain from the duct. DCPP will enhance these provisions to ensure that water cannot enter the 480V switchgear room upstream of the ducts when the fan is turned off. There are no other openings in the supply or exhaust duct through which fluids could enter. LRA Table
A4-1 is amended to include this commitment.
PG&E Letter DCL-11-001 Page 3 of 6 RAI 2.3-1 In a telephone conference call held on December 14, 2010, the NRC requested additional information in regards to safety-re lated tubing attached to non-safety related tubing through solenoid operated valves in the compressed air system. In particular, the NRC wants to know the methodology used for scoping these portions of the system.
PG&E agreed to supplement the response to RAI 2.3-1.
PG&E Letter DCL-10-137, dated October 15, 2010, clarified the methodology for indicating the boundary between safety-rela ted and nonsafety-related structures, systems and components (SSCs). This met hod was then applied to valves in the compressed air system.
The following clarifies the scoping methodology used for safety-related transitioning to nonsafety-related SSCs in the compress ed air system as well as the nitrogen and hydrogen system. DCPP has included all safe ty-related and nonsafety-related backup air system tubing in scope up to the first se ismic or equivalent anchor on the nonsafety-related side of the code break valve (e ither a solenoid or a check valve).
With respect to the nitrogen and hydrogen syst em, these nonsafety-related systems are not in scope of license renewal. All nons afety-related nitrogen piping and valves connected to safety-related instrument air back-up piping and fluid systems in the emergency core cooling system are in scope up to the first seismic anchor or equivalent anchor on the nonsafety-related side of the code break valve.
PG&E Letter DCL-11-001 Page 4 of 6 RAI 2.3-3 In a telephone conference call held on December 14, 2010, the NRC requested additional information in regards to the or ientation of safety-related and non safety-related components in electrical pull boxes.
PG&E agreed to supplement the response to RAI 2.3-3.
PG&E Supplemental Response to RAI 2.3-3
PG&E Letter DCL-10-128, dated October 12, 2010, discussed electrical pull box drain configuration. In particular, the drain piping components and sump for electrical pull boxes are oriented such that fluids cannot sp ray or leak onto safety-related cables or conduits. The following provides the additional information on the pull box configuration that demonstrates fluids cannot spray or leak onto safety-related cables or conduits.
The in-scope electrical pull boxes between t he intake structure and turbine building are designed with drain conduits that drain to pull boxes at the intake and turbine building.
The end pull boxes drain to a building sump or to an in-ground sump that has a level
alarm and an automatic sump pump. The pu ll box sump pump and alarm features are tested annually in accordance with the plant maintenance work orders. The remaining in-scope electrical pull boxes are located in side of in-scope structures that provide shelter and protection and are not subject to w eather related water intrusion. Some of the indoor pull boxes are also equipped with dr ain conduits that drain to a building sump. As discussed in PG&E Letter DCL-10-148, dated November 24, 2010, the pull box inspection program has been effective in preventing pull box flooding and cable submergence in all in-scope 480V and higher power cable pull boxes.
The in-scope pull boxes that drain to an aut omatic pump equipped sump are physically separated from the sump, pump and pump disc harge piping. The pull boxes drain to the sump via a 4-inch drain pipe. T he sump pump discharge line is routed underground to the turbine building and ultimately t he turbine building sump. The sump pump discharge line does not transit through any of the in-scope pull boxes, therefore it cannot leak or spray on any in-scope cables.
Since the in-scope pull boxes are physically separated from the sump, pump and pump discharge piping, no safety-related cables or conduits can be sprayed or leaked on.
PG&E Letter DCL-11-001 Page 5 of 6 RAI 2.3.3.7-3
In a telephone conference call held on December 14, 2010, the NRC requested additional information in regards to water traps in the compressed air system whose failure could affect safety-related equipment.
PG&E agreed to supplement the re sponse to RAI 2.3.3.7-3.
PG&E Supplement to RAI 2.3.3.7-3
PG&E Letter DCL-10-140, dated November 8, 2010, discussed the effect of water trap failure and loss of instrument air to safety-re lated air operated components. Further, the RAI response detailed how the compressed air system is a dry system.
As described in the DCPP License Renewal App lication (LRA), the only portions of the compressed air system that are within the scope of license renewal are the backup air systems. A confirmatory walk-down was performed to assess the surroundings of the water traps. The water traps are locat ed on LRA drawings LR-DCPP-25-106725-50 (location 503-E) and LR-DCPP-25-107725-42 (l ocation 423-D). These water traps could contain approximately 4 ounces of liquid.
In the event of failure, a minor amount of water could spray on nearby safety-relat ed equipment. Approximately 2 ft away from the wall is safety-related ductwork and approxim ately 2 ft to the west on the same wall are safety-related solenoid valves.
The water traps are located on instrument air lines to temperature control valves regulating supply air heating coils. This por tion of the system is no longer in use as described in PG&E Letter DCL-10-140. Since the compressed air system is dry and the instrument air lines which contain the wa ter traps are not used, PG&E will close the isolation valve upstream of the traps and t hen drain the traps. LRA Table A4-1 is amended to include this commitment.
PG&E Letter DCL-11-001 Page 6 of 6 RAI 2.3.3.14-1
In a telephone conference call held on December 14, 2010, the NRC requested additional information in regards to the in progress design changes on the diesel
generator starting air and turbocharger air compressor unloader line.
PG&E agreed to supplement the re sponse to RAI 2.3.3.14-1.
PG&E Supplemental Response to RAI 2.3.3.14-1
PG&E Letter DCL-10-137, dated October 15, 2010, credited the nonsafety-related tubing associated with the diesel generator starting air and turbocharger air compressor unloader line with the structural support in tended function. This was because the boundary of nonsafety-related tubing terminated at a valve integral to the compressor head which served as positive isolat ion of the pressure boundary.
An upgrade is being implemented on the diesel generator starting air compressors and the diesel generator turbocharger air compresso rs. This relocates the connection point of the unloader tubing line. Prior to the upgrade, the unloader tubing was connected to the air receiver at a dedicated connection wit h a normally open manual valve. The tank connection nozzle and valve were safety-related. The unloader tubing was nonsafety-
related.
The upgrade relocates the unloader tubing line to the compressor discharge piping at a
location between the compressor and the code break check valve in the air supply line
to the air receiver, such that it is upstream of the seismic anchor. The motive force for unloader operation with this new configurat ion is the air within the compressor discharge line rather than the air receiver itself. The existing check valve in the compressor discharge line (adjacent to the air receiver) remains the code break and
serves as the pressure boundary between the ai r receiver and all of the following: the compressor, compressor discharge piping, and the unloader tubing. The internal environment of the unloader tubi ng is dried air; therefore the tubing does not perform a leakage boundary (spatial interaction) intended function. Since the unloader tubing line connects at a point on the upstream side of the seismic anchor, the tubing is not required to provide the intended function of stru ctural integrity (attached). Therefore, the entire length of the unl oader tubing is not within t he scope of license renewal.
License Renewal Application Tables 2.3.3-14 and 3.3.2-14 are amended to reflect this change. The manual valve at the old tubing connection point is changed to normally
closed and capped. The connected tubing is removed and rerouted.
This upgrade has been implemented on all Unit 1 diesel generator starting air and turbocharger air compressors. Implementation completion for all Unit 2 diesel generator starting air and turbocharger air compressor upgrades is planned for April, 2011.
License Renewal Application Table A4-1 is amended to include this commitment.
PG&E Letter DCL-11-001 Page 1 of 6 LRA Amendment 37 LRA Section RAI Table 2.3.3-12 2.1-1 Table 2.3.3-14 2.3.3.14-1 Table 3.3.2-12 2.1-1 Table 3.3.2-14 2.3.3.14-1 Table A4-1 2.1-1, 2.3.3.7-3, 2.3.3.14-1
PG&E Letter DCL-11-001 Page 2 of 6 Section 2.3 SCOPING AND SCREENING RESULTS MECHANICAL SYSTEMS Table 2.3.3-12 Fire Protection System Component Type Intended Function Valve Leakage Boundary (spatial)
Pressure Boundary PG&E Letter DCL-11-001 Page 3 of 6 Section 2.3 SCOPING AND SCREENING RESULTS MECHANICAL SYSTEMS Table 2.3.3-14 Diesel Generator System Component Type Intended Function Tubing Pressure Boundary Structural Integrity (attached)
Structural Support
PG&E Letter DCL-10-001 Page 4 of 6 Section 3.3 AGING MANAGEMENT OF AUXILIARY SYSTEMS Table 3.3.2-12 Auxiliary Systems - Summary of Aging Management Evaluation - Fire Protection System Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Vol.
2 Item Table 1 Item Notes Valve LBS , PB Copper Alloy Plant Indoor Air (Ext) None None VIII.I-2 3.4.1.41 A Valve LBS , PB Copper Alloy Raw Water (Int)
Loss of material Fire Water System (B2.1.13) VII.G-12 3.3.1.70 B PG&E Letter DCL-10-001 Page 5 of 6 Section 3.3 AGING MANAGEMENT OF AUXILIARY SYSTEMS Table 3.3.2-14 Auxiliary Systems - Summary of Aging Management Evaluation - Diesel Generator System Component Type Intended Function Material Environment Aging Effect Requiring Management Aging Management Program NUREG-1801 Vol.
2 Item Table 1 Item Notes Tubing PB , SS Copper AlloyDry Gas (Int)
None None VII.J-3 3.3.1.98 A Tubing PB , SS Copper Alloy Plant Indoor Air (Ext) None None V.F-3 3.2.1.53 A Tubing PB , SIA, SS Stainless Steel Dry Gas (Int)
None None VII.J-18 3.3.1.98 A Tubing PB , SIA, S S Stainless Steel Plant Indoor Air (Ext) None None VII.J-15 3.3.1.94 A PG&E Letter DCL-11-001 Page 6 of 6 Appendix AFinal Safety Analysis Report Supplement Table A4-1 License Renewal Commitments Item # Commitment LRA Section Implementation Schedule 60 PG&E will enhance provisions in the HVAC ducting from the 480V switchgear room that allow water to drain from the exhaust ducti ng so water cannot enter the 480V switchgear room. Prior to the period of extended operation 61 PG&E will close the isolation valve upstream of the water traps and drain the traps in the compressed air system.
Prior to the period of extended operation 62 Implementation for all Unit 2 Diesel G enerator Starting Air and Turbocharger Air Compressor upgrades is planned for April, 2011.
Prior to the period of extended operation