PLA-6191, Proposed License Amendment Nos. 285 and 253, Extended Power Uprate Application Piping and Nondestructive Examination Technical Review Request for Additional Information Responses

Proposed License Amendment Nos. 285 and 253, Extended Power Uprate Application Piping and Nondestructive Examination Technical Review Request for Additional Information Responses

ML071360041
Person / Time
Site:	Susquehanna
Issue date:	05/03/2007
From:	Mckinney B Susquehanna
To:	Document Control Desk, NRC/NRR/ADRO
References
PLA-6191, TAC MD3309, TAC MD3310
Download: ML071360041 (10)

Text

Britt T. McKinney PPL Susquehanna, LLC " ~ig /

Sr. Vice President & Chief Nuclear Officer 769 Salem Boulevard * ~ lie ~

Berwick, PA 18603 4 Tel. 570.542.3149 Fax 570.542.1504 --

btmckinney@pplweb.com MAY 0 3 2007 P3p P .

U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop OP 1-17 Washington, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION PROPOSED LICENSE AMENDMENT NO. 285 FOR UNIT 1 OPERATING LICENSE NO. NPF-14 AND PROPOSED LICENSE AMENDMENT NO. 253 FOR UNIT 2 OPERATING LICENSE NO. NPF-22 EXTENDED POWER UPRATE APPLICATION RE:

PIPING AND NONDESTRUCTIVE EXAMINATION TECHNICAL REVIEW REQUEST FOR ADDITIONAL INFORMATION RESPONSES Docket Nos. 50-387 PLA-6191 and 50-388 References. 1) PPL Letter PLA-6076, B. T McKinney (PPL)to USNRC, "ProposedLicense Amendment Numbers 285for Unit I Operating License No. NPF-14 and 253 for Unit 2 OperatingLicense No. NPF-22 Constant PressurePower Uprate,"dated October 11, 2006.

2) Letter, R. V Guzman (NRC) to B. T McKinney (PPL),

"Requestfor Additional Information (RAI) -

SusquehannaSteam Electric Station, Units I and 2 (SSES 1 and 2) -

Extended Power UprateApplication Re.- Pipingand Nondestructive Examination Technical Review (TAC Nos. MD3309 and MD3310), "dated April 10, 2007.

Pursuant to 10 CFR 50.90, PPL Susquehanna LLC (PPL) requested in Reference 1 approval of amendments to the Susquehanna Steam Electric Station (SSES) Unit 1 and Unit 2 Operating Licenses (OLs) and Technical Specifications (TSs) to increase the maximum power level authorized from 3489 Megawatts Thermal (MWt) to 3952 MWt, an approximate 13% increase in thermal power. The proposed Constant Pressure Power Uprate (CPPU) represents an increase of approximately 20% above the Original Licensed Thermal Power (OLTP).

The purpose of this letter is to provide responses to the Request for Additional Information transmitted to PPL in Reference 2.

The Enclosure contains the PPL responses.

,4cof

Document Control Desk PLA-6191 There are no new regulatory commitments associated with this submittal.

PPL has reviewed the "No Significant Hazards Consideration" and the "Environmental Consideration" submitted with Reference 1 relative to the Enclosure. We have determined that there are no changes required to either of these documents.

If you have any questions or require additional information, please contact Mr. Michael H. Crowthers at (610) 774-7766.

I declare under perjury that the foregoing is true and correct.

Executed on: \.> 0 B. T. McKinney

Enclosure:

Request for Additional Information Responses Copy: NRC Region I Mr. A. J. Blamey, NRC Sr. Resident Inspector Mr. R. V. Guzman, NRC Sr. Project Manager Mr. R. R. Janati, DEP/BRP

ENCLOSURE TO PLA-6191 PPL EPU Request for Additional Information Responses

Enclosure to PLA-6191 Page 1 of 7 NRC Question 1:

Identify the materials of construction for the reactor coolant pressure boundary (RCPB) piping and safe-ends. Discuss and explain the effect of the requested power uprate on the RCPB piping and safe-end materials and its impact on the potential degradation mechanisms.

PPL Response:

The materials of construction for the RCPB piping and safe-ends are:

SSES Units 1 and 2 RCPB Piping and Safe End Materials

~=§i~; Description j .Safe End ' wPipinlg~ "

SA336 Cl Recirculation Outlet (NI) F8 SA358 TP304 SA182 Recirculation Inlet (N2) F316L SA358 TP304 Steam Outlet (N3) SA508 Cl I SA106 GrB Feedwater (N4) SA508 C1 I SA333 Gr6 Core Spray (N5) see note 1 SB166 SA358 TP304 Head Spray (N6B) None SA312 TP304 Spare (N6A) None Blind Flange, SA508 Cl I Head Vent (N7) None SA106 GrB SA336 Cl Jet Pump Instrument (N8) F8 SA312 TP304L Control Rod Drive Hydraulic Return (N9) None Pipe Cap, SB 166 SA336 Cl Core Delta-P and SLC (N10) F8 SA312 TP304L Water Level (N 11) None SA106 GrB Water Level (N 12) None SA 106 GrB Seal Leak Detection (N 13) None SA106 GrB Bottom Head Drain/RWCU Suction (N15) None SA106 GrB Water Level (N 16) None SA 106 GrB Control Rod Drive Penetrations None SA312 TP304 In-Core Housing Penetrations None SA213 TP304 Notes:

1. The Core Spray (N5) nozzles safe-end extensions are SA336 Cl F8.

2. NUREG 0313 applies only to components 4" inches and larger. Of the above, the N 10 through N 16 and the In-core Housing Penetrations are less than 4".

Enclosure to PLA-6191 Page 2 of 7 Implementation of EPU will result in an increase in neutron fluence, flow rates, and operating temperature changes. The primary material effects are potential fatigue usage increases, Irradiation Assisted Stress Corrosion Cracking (IASCC), Flow-Accelerated Corrosion (FAC), and Flow Induced Vibration (FIV). The CPPU impact on these degradation mechanisms are as follows:

" The increase in fatigue usage is addressed in Attachment 4 of Reference 1 Section 3.2 for the RPV and Safe Ends and in Section 3.5.1 for RCPB piping. The increases are not significant and within allowable.

" The increase in fluence and the potential IASCC effect on the RCPB Safe Ends and Piping is negligible since the fluence at these locations are not significant as addressed in the Attachment 4 of Reference 1 Section 10.7.

" The increase in flow rates does not have a significant effect on the FAC monitoring program as addressed in Attachment 4 of Reference 1 Section 10.7.

" The increase in flow rates does have potential significant effects on FIV.

Reference 1 Attachment 4, Section 3.4.1 and Reference 1 Attachment 9 present the plan to predict, monitor, and correct FIV effects.

NRC Ouestion 2:

Identify the RCPB piping and safe-end components that are susceptible to intergranular stress corrosion cracking (IGSCC). Discuss any augmented inspection programs that have been implemented and the adequacy of the augmented inspection programs in light of the EPU.

PPL Response:

SSES was designed, fabricated, and constructed in accordance with the guidance in NUREG-0313, Rev. 1. The SSES IGSCC augmented inspection program is based on NUREG-0313, Rev. 2, Boiling Water Reactor Vessel and Internals Project (BWRVIP) report BWRVIP-75-A, and ASME Section XI.

Most of the RCPB piping and safe-end component welds are either Category A [not susceptible to IGSCC due to their metallurgical properties] or B [protected from IGSCC since these join similar materials with Inductive Heat Stress Improvement (IHSI) applied].

Enclosure to PLA-6191 Page 3 of 7 Category C components, that mostly involve steels welded to nickel-based alloys, had Mechanical Stress Improvement Process applied but are considered susceptible to IGSCC since there may be latent flaws that existed prior to MSIP. There are 28 Category C weld locations in Unit 1 and 29 in Unit 2.

The tables that follow identify the SSES Units 1 and 2 Category C welds as well as Category E [repaired welds]. Categories A and B are not listed since they are protected from IGSCC. SSES has no Category D [non-resistant material with no IHSI or MSIP applied] or Category F welds [a known flaw left in place].

Enclosure to PLA-6191 Page 4 of 7 Reactor Pressure Vessel (RPV) Outlet NIA, Safe End to Nozzle C RPV Outlet N1B, Nozzle to Safe End WELD (1)

OVERLAY E RPV Inlet N2A, Safe End to Nozzle C RPV Inlet N2B, Safe End to Nozzle C RPV Inlet N2C, Safe End to Nozzle C RPV Inlet N2D, Safe End to Nozzle C RPV Inlet N2E, Safe End to Nozzle C RPV Inlet N2F, Safe End to Nozzle C RPV Inlet N2G, Safe End to Nozzle C RPV Inlet N2H, Safe End to Nozzle C RPV Inlet N2J, Safe End to Nozzle WELD OVERLAY E (1)

RPV Inlet N2K, Safe End to Nozzle C RPV CORE SPRAY N5A, Safe End to Nozzle C RPV CORE SPRAY N5A, Safe End Extension to Safe End C RPV CORE SPRAY N5B, Safe End to Nozzle C RPV CORE SPRAY N5B, Safe End Extension to Safe End C RPV Jet pump Inst. N8A,Nozzle to Safe End C RPV Jet pump Inst. N8B, Nozzle to Safe End C RPV Control Rod Drive N9, Nozzle to Cap C RHR Pump Suction, Elbow to Reducer C Residual Heat Removal (RHR) to RPV Head Spray, Elbow to Pipe C RHR to RPV Head Spray, Pipe to Valve C RHR to RPV Head Spray, Valve to Flued Head C RHR to RPV Head Spray, Flued Head to Elbow C RHR from Reactor Recirculation System (RRS), Valve to Elbow C RHR to RRS, Pipe to Elbow C RHR to RRS, Elbow to Pipe C RHR to RRS, Elbow to Pipe C RHR to RRS, Pipe to Valve C RHR to RRS, Pipe to Valve C Note:

1. Two locations had crack indications and weld overlays (Category E).

Enclosure to PLA-6191 Page 5 of 7 IGSCC CATEGORIES C I GSCC SSES Unit 2 - Weld~Descrilption< < CategoryN RPV Outlet NIA, Safe End to Nozzle C RPV Outlet NIB, Safe End to Nozzle C RPV Inlet N2A, Safe End to Nozzle C RPV Inlet N2B, Safe End to Nozzle C RPV Inlet N2C, Safe End to Nozzle C RPV Inlet N2D, Safe End to Nozzle C RPV Inlet N2E, Safe End to Nozzle C RPV Inlet N2F, Safe End to Nozzle C RPV Inlet N2G, Safe End to Nozzle C RPV Inlet N2H, Safe End to Nozzle C RPV Inlet N2J, Safe End to Nozzle C RPV Inlet N2K, Safe End to Nozzle C RPV CORE SPRAY N5A, Safe End to Nozzle C RPV CORE SPRAY N5A, Safe End Extension to Safe End C RPV CORE SPRAY N5B, Safe End to Nozzle C RPV CORE SPRAY N5B, Safe End Extension to Safe End C RPV Jet pump Inst. N8A,Nozzle to Safe End C RPV Jet pump Inst. N8B, Nozzle to Safe End C RPV CRD N9, Nozzle to Cap C RRS Loop A, Pipe to Pipe C RHR Pump Suction, Elbow to Reducer C RHR to RPV Head Spray, Valve to Flued Head C RHR to RPV Head Spray, Flued Head to Elbow C RHR from RRS, Valve to Elbow C RHR to RRS, Pipe to Elbow C RHR to RRS, Elbow to Pipe C RHR to RRS, Elbow to Pipe C RHR to RRS, Pipe to Valve C RHR to RRS, Pipe to Valve C The evaluation of the effects of the CPPU on the RCPB piping and safe-end materials are as explained in Section 3.6.1 of NEDC-32523P-A, "Licensing Topical Report Generic Evaluations of General Electric Boiling Water Reactor Extended Power Uprate,"

(ELTR2) (Ref 3 of Attachment 4 of PPL's CPPU License Amendment Request). PPL meets the generic qualification by the following:

• Replacing susceptible materials and elimination of creviced welds such as the recirculation piping safe ends to minimize material susceptibility to IGSCC.

Enclosure to PLA-6191 Page 6 of 7

• Eliminating the presence of residual stresses by the application of Mechanical Stress Improvement or Inductive Heat Stress Improvement.

These residual stresses contain harmful tensile stresses that assist IGSCC.

Since the system conditions are not changing significantly CPPU will have negligible effects on tensile stresses due to increased temperatures, pressures, and flows.

" Reducing the oxidizing environment by the application of hydrogen water chemistry (HWC). CPPU will tend to increase the oxidizing environment slightly. The response to question 4 describes the steps that will be taken to maintain the oxidizing mitigation required to prevent IGSCC.

Based on the above, it is concluded that the existing maintenance, inspection and procedures are not affected by operation at CPPU conditions. This is because the existing augmented inspection programs collectively provide early detection of crack detection.

The existing augmented inspection programs are adequate at CPPU conditions.

NRC Question 3:

Identify all flawed components including overlay repaired welds that have been accepted for continued service by analytical evaluation based on American Society of Mechanical Engineers (ASME),Section XI rules. Discuss the adequacy of such analysis considering the effect of the EPU on the flaws.

PPL Response:

There are no known flaws in the RRS piping that have not been repaired by weld overlays. Two weld flaws that were repaired by weld overlays are located in Unit 1 on the NIB (28" recirculation outlet) and the N2J (12" recirculation inlet) nozzles. Both flaws and repairs were analyzed and the repairs qualified to the ASME Section XI, Division 1 Code, 1989 Edition. The existing analyses are applicable also to CPPU conditions because CPPU makes no significant change to the operating temperature, pressure, and flow rate of the RRS piping. The RRS CLTP and CPPU temperatures, pressures, and flow rates are presented in Attachment 4 of PLA-6076, Section 3.5.1. The changes from CLTP to CPPU are a 1% decrease in temperature, 0.1% increase in pressure, and 2.2% increase in flow rate.

NRC Question 4:

Identify the mitigation processes being applied at SSES, Units 1 and 2 to reduce the RCPB component's susceptibility to IGSCC, and discuss the effect of the requested EPU on the effectiveness of these mitigation processes. For example, if hydrogen water chemistry (HWC) was applied at the plant, it would be necessary to perform the

Enclosure to PLA-6191 Page 7 of 7 electrochemical potential measurements at the most limiting locations to ensure that the applied hydrogen injection rate is adequate to maintain the effectiveness of HWC (since oxygen content in the coolant is expected to increase due to increased radiolysis of water resulting from extended power uprate).

PPL Response:

Inductive Heat Stress Improvement (IHSI) and Mechanical Stress Improvement Process (MSIP) have been applied at SSES to reduce the RCPB component's susceptibility to IGSCC. Most welds with IGSCC susceptible material, except the dissimilar metal welds, were stress improved using IHSI before operation or within 2 years after operation.

MSIP was performed after 10 years of operation on all the dissimilar metal welds and those remaining few welds that could not be stress improved with IHSI. CPPU will not change the effectiveness of these processes since CPPU does not change the IGSCC resistance of a material nor affect the removal of beneficial compressive stresses with the IHSI or MSIP processes.

In addition, the Recirculation Inlet Safe Ends were replaced with 316L material with a carbon content of <0.02% prior to operation in order to reduce susceptibility to IGSCC.

SSES also utilizes a Moderate Hydrogen Water Chemistry (HWC-M) program to mitigate IGSCC. SSES is a Category 1 plant in accordance with BWRVIP-130, EPRI BWR Water Chemistry Guidelines. Hydrogen injection rate will be increased at EPU conditions in order to maintain feedwater hydrogen concentration at a nominal 2.0 parts per million (ppm). Prior to and during the initial period of hydrogen injection, electrochemical potential (ECP) sensors were installed as an integral part of a special Local Power Range Monitor (LPRM) assembly, located at core grid 32-09 to monitor water from the lower plenum region of the core. This is considered a limiting location for the purposes of ECP measurement. SSES obtained benchmark ECP measurements as the primary parameter to monitor effectiveness of hydrogen water chemistry.. These probes have since burned out and will be replaced on the lead unit prior to operation at EPU conditions in accordance with BWRVIP-62 recommendations.

Secondary parameter data has also been collected, maintained and correlated during the operation of the ECP probes and after failure due to burnout to supplement the ECP probe data. The secondary parameters included feedwater hydrogen injection rate, reactor rater cleanup influent dissolved oxygen and main steam line radiation. These secondary parameters will continue to be used for mitigation monitoring. The EPRI Boiling Water Reactor Vessel and Internals Application Radiolysis Model is also used to evaluate the effectiveness of hydrogen injection.