ML14254A131

NRR E-mail Capture - Peach Bottom & Quad Cities---RAI Questions for Relief Request I4R-55 TAC MF3799, Mf 3800, MF3801 and MF3802

ML14254A131
Person / Time
Site:	Peach Bottom, Quad Cities
Issue date:	09/08/2014
From:	Joel Wiebe Plant Licensing Branch III
To:	Tom Loomis Exelon Generation Co
References
MF3799, MF3800, MF3801, MF3802
Download: ML14254A131 (3)

Text

NRR-PMDAPEm Resource From: Wiebe, Joel Sent: Monday, September 08, 2014 1:59 PM To: Tom Loomis

Subject:

Peach bottom & Quad Cities---RAI questions for Relief Request I4R-55 TAC MF3799, MF 3800, MF3801 and MF3802

Tom, By letter dated March 28, 2014 (Agencywide Documents and Access Management System (ADAMS)

Accession No. ML14090A140), Exelon Generation Company, LLC (the licensee) requested relief from certain requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, at the Peach Bottom Atomic Power Station, Units 2 and 3, and Quad Cities Nuclear Power Station, Units 1 and 2. As documented in Relief Requests I4R-55 and I5R-12, the licensee proposed to use modified ASME Code Case N-513-3 for the repair of high pressure service water (HPSW) system piping at Peach Bottom and residual heat removal service water (RHRSW) system piping at Quad Cities. To complete its review, the Nuclear Regulatory Commission (NRC) requests the following additional information:

1. In the relief request, the licensee referenced several precedents. It does not appear to the NRC staff that the precedents provided address relief for a generic (addressing a future leak) long term (up to 18-24 months),

higher pressure (greater than 275 psi), and raw water application. Please discuss the applicability of the precedents to Relief Request I4R-55.

2. The concepts of what constitute moderate energy piping and the limitation of ASME Code Case N-513 to moderate energy systems is well established. The NRC staff believes that authorizing the proposed alternative may create confusion regarding these issues. It is not clear to the NRC that the justification provided for the proposed alternative is sufficient given the potential confusion which may be created. Please provide comments regarding this issue.

3. The NRC staff believes that authorization of the proposed alternative may establish precedent for the use of Code Case N-513 at pressures above the current limits for moderate energy piping at plants other than Peach Bottom and Quad Cities. The NRC staff believes that establishing such a precedent may have far reaching consequences, some of which may be adverse. Any information which is known by the licensee regarding the extent to which other plants and/or licensees may have piping systems which are similar to those for which relief is requested would be useful in the NRCs decision making process. The NRC is aware that the licensee may have no knowledge of such systems and is not asking the licensee to acquire such information. To the extent which information regarding similar piping systems at other locations is available, please provide a discussion of the extent to which similar piping systems exist within the industry.

4. The licensee submitted both relief requests under Title 10, Code of Federal Regulations, Part 50 (10 CFR),

55a(a)(3)(i) which specifies that the proposed alternative provides an acceptable level of quality and safety.

This means that the proposed alterative would provide an equivalent level of quality and safety as that of an ASME Code repair. The NRC staff believes that the use of the proposed alternative, i.e., continued operation with through wall leakage provides a lower level of quality and safety when compared with an ASME Code compliant repair. The NRC staff believes that requesting the use of the proposed alternative under 10 CFR 50.55a(a)(3)(ii) may be more appropriate. Please justify it is appropriate to make this request under 10 CFR 50.55a(a)(3)(i) rather than 10 CFR 50.55a(a)(3)(ii).

5. The relief request states that the operating pressure is less than or equal to 375 psi for the HPSW and RHRSW system piping at Peach Bottom and Quad Cities, respectively. (a) Discuss the design pressure, design temperature and the maximum operating temperature of the HPSW and RHRSW systems. (b) Discuss any segment of the HPSW and RHRSW piping that is inaccessibility for visual and ultrasonic examinations (e.g., buried underground, covered with insulation, and interferences). In this discussion include how periodic 1

monitoring of the leakage of any inaccessible segment(s) can be conducted as required by Code Case N-513-

3. (c) Provide all pipe diameters and wall thickness of the HPSW and RHRSW to which the proposed alternative will be applicable.

6. The relief requests stated that both HPSW and RHRSW systems are used only during testing and plant shutdown. It appears that both systems will not be used during plant operation. The NRC staff understands that when both systems are needed to be functional during plant shutdown, performing an ASME Code repair would be a hardship. (a) However, if a leak occurs during the normal plant operation while the HPSW and RHRSW systems are not being used, discuss why the proposed alternative is needed and why an ASME Code repair cannot be performed. (b) Discuss whether these two piping systems are needed to be operable during an emergency condition. If yes, justify why the proposed alternative is permitted to be used during the emergency condition.

7. The Summary section of the relief requests states that the allowable leakage of the HPSW or RHRSW piping is 100 gallons per minute (gpm). This is a significant leak rate. The NRC staff notes that NRC Branch Technical Position 3-3, Revision 3, Protection Against Postulated Piping Failures in Fluid Systems Outside Containment, and Branch Technical Position 3-4, Revision 2, Postulated Rupture Locations in Fluid System Piping Inside and Outside Containment, of Standard Review Plan, NUREG-0800, provide guidance on flooding analysis. (a) Discuss whether a 100 gpm leak rate is within the design basis flooding analysis associated with the rooms, buildings, and compartments that HPSW and RHRSW piping are located in light of a significant allowable leak rate of 100 gpm. (b) Discuss whether the pumps of these two systems have the capacity to make up the mass flow to compensate for a 100 gpm leak rate to maintain the intended function of both HPSW and RHRSW systems. (c) If the leak rate exceeds 100 gpm, discuss corrective actions. (d) The NRC staff believes that an allowable leak rate of 100 gpm is too high of a limit. Provide either a justification for such a high allowable leak rate or lower the allowable leak rate.

8. Page 6 of Attachment 2 discussed the average cover thickness calculated for 275 psi and 375 psi pressure. The average cover thickness and average diameter equations as specified in Code Case N-513-3 are to demonstrate acceptability under the branch reinforcement requirements. Demonstrate that a leaking pipe with a leak rate of 100 gpm at a pressure of 375 psi will satisfy the branch reinforcement requirements of Code Case N-513-3.

9. Page 6 of Attachment 2 discusses the result of jet thrust force calculations between a pressure of 275 psi and 375 psi. Demonstrate that the jet thrust force calculated at a pressure of 375 psi will not be detrimental to the adjacent safety-related systems, structures and components.

10. Page 7 of Attachment 2 states that a pipe opening (hole) with a diameter of 0.5 inches will result in a leak rate of 90 gpm. Provide the detailed calculation to show how 90 gpm is derived from a 0.5-inch diameter hole.

2

Hearing Identifier: NRR_PMDA Email Number: 1563 Mail Envelope Properties (1A97AE0578A58B46BC77AA0B5DBD72020124996494A2)

Subject:

Peach bottom & Quad Cities---RAI questions for Relief Request I4R-55 TAC MF3799, MF 3800, MF3801 and MF3802 Sent Date: 9/8/2014 1:59:04 PM Received Date: 9/8/2014 1:59:00 PM From: Wiebe, Joel Created By: Joel.Wiebe@nrc.gov Recipients:

"Tom Loomis" <thomas.loomis@exeloncorp.com>

Tracking Status: None Post Office: HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 7194 9/8/2014 1:59:00 PM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received: