NOC-AE-12002928, Supplement to Relief Request RR-ENG-3-09 for the Essential Cooling Water System

Supplement to Relief Request RR-ENG-3-09 for the Essential Cooling Water System

ML12341A229
Person / Time
Site:	South Texas
Issue date:	11/14/2012
From:	Rencurrel D South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-12002928, TAC ME9806, G25
Download: ML12341A229 (8)

Text

Nuclear Operating Company South Texas ProjectEectIc Genermtg Stat'on C.OBox289 *dodvorth, Tes 77483 -

November 14, 2012 NOC-AE-12002928 File No.: G25 10 CFR 50.55a U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Unit 2 Docket No. STN 50-499 Supplement to Relief Request RR-ENG-3-09 for the Essential Cooling Water System (TAC No. ME9806)

Reference:

1. Letter, D. W. Rencurrel to NRC Document Control Desk, "Request for Relief from ASME Boiler and Pressure Vessel Code, Section Xl Requirements for the Essential Cooling Water System (Relief Request RR-ENG-3-09)," dated October 16, 2012 (NOC-AE-1 2002898) (ML12299A287).

2. Meeting Summary Memoranda from Carl F. Lyon, NRC, South Texas Project Unit 2 - Summary of Telephone Conference on November 8, 2012, to discuss the Licensee's Request for Relief RR-ENG-3-09 (TAC No. ME9806).

As a supplement to Reference 1 and in response to Reference 2, the STP Nuclear Operating Company (STPNOC) submits the information provided in Attachment 1 to this letter in support of the review of request for relief RR-ENG-3-09. Attachment 2 to this letter revises and supersedes the list of commitments previously submitted in Reference 1, in order to clarify the location of the area to be visually inspected under the proposed augmented monitoring plan.

A list of commitments is provided in Attachment 2 to this letter. There are no other regulatory commitments in this letter.

If there are any questions, please contact Coley Chappell at 361-972-4745, or me at 361-972-7867.

D. W. Rencurrel Senior Vice President ccc I0 q7 Attachments: 1. Supplement to RR-ENG-3-09 for STP Unit 2 Essential Cooling Water System 10( (4-

2. List of Commitments FE1UARTE f5 oivflL STI: 33623458

NOC-AE-12002928 Page 2 of 2 cc: (paper copy) (electronic copy)

Regional Administrator, Region IV A. H. Gutterman, Esquire U. S. Nuclear Regulatory Commission Morgan, Lewis & Bockius LLP 1600 East Lamar Boulevard Arlington, TX 76011-4511 Balwant K. Singal Carl F. Lyon U. S. Nuclear Regulatory Commission Balwant K. Singal John Ragan Senior Project Manager Chris O'Hara U.S. Nuclear Regulatory Commission Jim von Suskil One White Flint North (MS 8 B1) NRG South Texas LP 11555 Rockville Pike Rockville, MD 20852 NRC Resident Inspector Kevin Polio U. S. Nuclear Regulatory Commission Richard Pena P.O. Box 289, Mail Code: MN116 City Public Service Wadsworth, TX 77483 C. M. Canady Peter Nemeth City of Austin Crain Caton & James, P.C.

Electric Utility Department 721 Barton Springs Road C. Mele Austin, TX 78704 City of Austin Carl F. Lyon Richard A. Ratliff Project Manager Texas Department of State Health Services U.S. Nuclear Regulatory Commission One White Flint North (MS 8 B1A) Alice Rogers 11555 Rockville Pike Texas Department of State Health Services Rockville, MD 20852

Attachment 1 NOC-AE-12002928 Page 1 of 5 Supplement to RR-ENG-3-09 for STP Unit 2 Essential Cooling Water System On November 8, 2012, members of the NRC staff held a telephone conference with representatives from STPNOC to discuss request for relief RR-ENG-3-09 (TAC No. ME9806) dated October 16, 2012, for South Texas Project Unit 2.

STPNOC provided clarifying information regarding (1) the location of the through-wall indication on the weld neck flange at valve 2-EW-0274 (Essential Chillers 21 B/22B to Essential Chillers 21A/22A ECW Cross-Tie Valve) and (2) the purpose of the cross-tie piping.

Based on the discussion, STPNOC agreed to supplement its letter dated October 16, 2012 (ML12299A287) and provide the following information:

1. A detailed description of the location of the through-wall indication with regard to the flange, cross-tie piping, and associated valves.

The inactive seepage (discoloration) was identified on the heat affected zone of the weld neck flange base metal, close to the pipe weld, on the segment of Essential Cooling Water (ECW) system line 10"EW2283WT3 in the cross connect line, or cross-tie piping, between Trains 2A and 2B near valve 2-EW-0274, Essential Chillers 21 B/22B to Essential Chillers 21A/22A ECW Cross-Tie Valve. The location of the flaw on the cross connect piping is between locked closed isolation valves 2-EW-0274 and 2-EW-0265, as shown below on Figures S-1 and S-2. An updated photo of the indication taken on October 30, 2012, which identifies the region of the flaw, is provided in Figure S-3.

2. A discussion of the purpose of the cross-tie during normal operations and accident conditions and the configuration during the normal and accident conditions of the cross-tie valves.

During normal operations and accident conditions, cross connect line 10"EW2283WT3 between ECW trains 2A and 2B is isolated by locked closed cross-tie valves and serves no purpose that is within the design basis assumptions of the ECW system. The cross-tie valves shall not be opened except for the purpose of filling an idle ECW train, as noted in Updated Final Safety Analysis Report (UFSAR) Figure 9.2.1-3.

3. A discussion of any references to the cross-tie in plant operating procedures, abnormal operating procedures, emergency operating procedures, design basis, and risk assessments.

Cross connect line 1 0"EW2283WT3 between ECW trains 2A and 2B is isolated from the ECW trains by cross tie valves that are locked closed in accordance with the normal system valve lineup. The cross-tie valves are referenced in system operating procedure OPOP02-EW-0001, Essential Cooling Water Operations, by a note/precaution that states the cross connect line cross-tie valves shall be locked closed and are not to be opened except to fill an idle ECW train. The procedure steps direct filling the loop using the ECW pump in the same train and do not direct use of the cross connect line. The cross-tie valves are referenced in the online isolation and restoration procedure OPOP1 1-EW-0002, ECW Product Lubricated Pump Online Isolation and Restoration, in valve lineup steps that

Attachment 1 NOC-AE-1 2002928 Page 2 of 5 ensure these valves remain locked closed as a condition for online removal from and return to service of the Product Lubricated Bearing Design ECW Pumps 2A and 2B.

General operating procedures, off-normal operating procedures, emergency operating procedures, and annunciator response procedures do not direct use of the cross connect line and cross-tie valves. The cross connect line may only be used for accident prevention or mitigation during events that are outside the ECW system design basis assumptions.

The cross-tie does not support any safety function or design basis function for the ECW system, as discussed below in response to Item 4, and is not credited in the Probabilistic Risk Assessment (PRA).

4. A discussion of the safety significance of the cross-tie piping and valves.

The cross connect line 100"EW2283WT3 between ECW trains 2A and 2B, including the cross-tie piping and valves, has no safety function and does not support any design basis function for the ECW system. The cross connect line is not required to support ECW

-system operation during and after a design basis accident (DBA). UFSAR section 9.2.1.2.2.3 states that all three ECW loops are designed to operate initially to provide cooling for equipment required to mitigate the consequences of a DBA and that a minimum of two ECW trains is required to operate following a DBA, considering.a single failure in the ECW system. The cross connect line, including cross-tie piping and associated valves, does not impact the ECW system capability to meet the ECW system design basis assuming either a single active or passive failure (reference UFSAR section 9.2.1.2 and Table 9.2.1-2).

The ECW system will satisfy all cooling requirements since the flaw is physically located in a section of piping isolated during normal plant operation. That isolation includes both locked closed valves and procedural requirements for their closure. Since the process (cooling) portion of the system is unaffected by this flaw, the cooling functional requirements of the system are also unaffected. The locked closed cross-tie valves that provide isolation between ECW trains 2A and 2B are not affected by the flaw in the cross connect piping. Since the location of the flaw is normally isolated from the process flow by locked closed isolation valves and is not an active leak, flooding of the Mechanical Auxiliary Building through this flaw is not possible. With no active leakage and the flaw located between two locked closed isolation valves, spray from the flaw location is not possible.

The slow progression of the dealloying process combined with the proposed augmented inspection of the affected area results in reasonable assurance of a noticeable change in any flaw parameter well before operability of the ECW system would be challenged. Since the cross-tie piping is normally isolated from the ECW system trains by locked closed cross-tie valves that are not affected by the piping flaw, a failure will not affect the ECW system function to supply cooling to the safety-related components, or result in damage to surrounding components. Therefore, immediate replacement of the affected cross-tie piping in accordance with Section Xl of the ASME Boiler and Pressure Vessel Code will not result in a significant increase in safety or quality when compared to the proposed alternative in the relief request.

Attachment 1 NOC-AE-1 2002928 Page 3 of 5 I FIGURE S-1: LOCATION OF ECW SYSTEM PIPING FLAW, PIPING DIAGRAM LC EW0265 LC I.

TRAIN A EW021 ECW PUMP SUPPLY HEADER Location of Flaw LC1027 IWT3 EW0274 LC TRAIN B I EW0267 ECW PUMP SUPPLY HEADER LC EW0275 LC LC EW0275.

11"-41 EW0276 TRAIN C I-ECW PUMP SUPPLY HEADER NOTE: Refer to ECW Piping and Instrumentation Diagram, drawing 5R289F05038#2, Sheets 1-3.

Attachment 1 NOC-AE-1 2002928 Page 4 of 5 FIGURE S-2: LOCATION OF ECW SYSTEM PIPING FLAW, ISOMETRIC VIEW Location of Flaw NOTE: Refer to isometric piping drawing 3M362PEW0229 Sheet 15, Essential Cooling Water System "EW"

Attachment 1 NOC-AE-12002928 Page 5 of 5 FIGURE S-3: DEALLOYED AREA AS OF OCTOBER 30, 2012

Attachment 2 NOC-AE-1 2002928 Page 1 of 1 LIST OF COMMITMENTS The following table identifies the actions to which the STP Nuclear Operating Company has committed and supersedes the commitment previously submitted in Attachment 2 to STPNOC letter NOC-AE-12002898 dated October 16, 2012 (ML12299A287). Changes are identified with the additional text underlined and the deleted text in strike-out.

Statements in this submittal with the exception of those in the table below are provided for information purposes and are not considered commitments.

Commitment Expected CR Action Completion No.

Date Perform monthly visual inspection of the affected reqion of line 10"EW2283WT3 aPd in the vicinity of 2-EW-0274 to detect changes in size of the discolored area or 06/01/2013 12-22876-5 leakage until a code repair is performed.

Re-evaluate structural integrity and the monitoring frequency if significant changes in the condition of the dealloyed area are found.