RS-08-025, Response to Request for Additional Information Related to Relief Request I3R-11, Hydrogen Recombiner System Piping - 10 CFR 50.55a(a)(3)(i).

Response to Request for Additional Information Related to Relief Request I3R-11, Hydrogen Recombiner System Piping - 10 CFR 50.55a(a)(3)(i).

ML080670036
Person / Time
Site:	LaSalle
Issue date:	03/06/2008
From:	Simpson P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-08-025, TAC MD5469, TAC MD5470
Download: ML080670036 (4)

Text

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Nuclear Exelon Generation www.exeloncorp.com 4300 Winfield Road Warrenville, IL 60555 10 CFR 50.55a RS-08-025 March 6, 2008 U . S . Nuclear Regulatory Commission ATTN : Document Control Desk Washington, D. C. 20555 LaSalle County Station, Units 1 and 2 Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374

Subject:

Response to Request for Additional Information Related to Relief Request 13R-11, "Hydrogen Recombiner System Piping - 10 CFR 50 .55a(a)(3)(i)"

References:

1 . Letter from S . R . Landahl (Exelon Generation Company, LLC) to U .S. NRC, "Submittal of Relief Requests Associated with the Third Inservice Inspection (ISI) Interval and the Second Containment Inservice Inspection (CISI)

Interval," dated April 30, 2007

2. Letter from S. R. Landahl (Exelon Generation Company, LLC) to U.S. NRC, "Additional Information Supporting the Relief Request Associated with the Third Inservice Inspection (ISI) Interval and the Second Containment Inservice Inspection (CISI) Interval," dated July 20, 2007

3. Letter from U. S. NRC to C. G . Pardee, (Exelon Generation Company, LLC),

"LaSalle County Station, Units 1 and 2 - Request for Additional Information related to Request for Relief 13R-11 Associated with the Third 10-Year Inservice Inspection Interval, Inspections Program Plan Risk-Informed Inservice Inspection of Piping (TAC NOS. MD5469 AND MD5470)," dated February 21, 2008 As part of Reference 1, supplemented by Reference 2, Exelon Generation Company, LLC, (EGC), requested NRC approval of a relief request for the Third Inservice Inspection (ISI) interval for LaSalle County Station (LSCS), Units 1 and 2. Specifically, 13R-11 requests relief from performing the VT-2 visual examination requirements specified for the Hydrogen Recombiner System cross-tie piping .

U. S. Nuclear Regulatory Commission March 6, 2008 Page 2 In Reference 3, the NRC requested additional information concerning relief request 13R-11 . The response to Reference 3 is provided in the attachment to this letter .

There are no regulatory commitments contained within this letter . Should you have any questions concerning this letter, please contact Alison Mackellar at (630) 657-2817 .

Patrick R . Simpson Manager - Licensing Attachment : Response to Request for Additional Information Related to Relief Request 13R-11

ATTACHMENT Response to Request for Additional Information Related to Relief Request 13R-11 Request for Additional Information "In reviewing the Exelon Generation Company's (Exelon's) submittal dated June 18, 2007, related to a relief request (RR) associated with the third inservice inspection interval, for the LaSalle County Station, Units 1 and 2 . The submittal requests relief from the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), Section XI, requirements for the selection and examination of Class 1 and 2 piping and welds. The Nuclear Regulatory Commission staff has determined that the following information is needed in order to complete its review :

(A) Please provide the information regarding at what temperature and pressure that the following tests will be performed for the accessible and inaccessible (the unit cross-tie piping) piping in the hydrogen recombiner system:

(1) The ASME Code required system leakage test to be conducted once each inspection period .

(2) The licensee's proposed alternative system pressure test at peak accident pressure, once each inspection interval .

(3) The 10-year hydrostatic test .

(4) The functional test of the hydrogen recombiner system during every refueling outage.

(B) Please describe the service conditions (temperature, pressure, environment, time at various conditions) of the unit cross-tie piping ."

Response Question A Amendments 172 and 158 for LaSalle County Station (LSCS), Units 1 and 2, (TAC NOS.

MC4496 and MC4497) dated April 22, 2005, deleted the Technical Specification (TS) requirements to maintain hydrogen recombiners . The hydrogen recombiner system is no longer used for recombining purposes. Only the mixing function of the system is being utilized. At LSCS the hydrogen recombiner system components (e.g., recombiner skid and piping) are all located inside the reactor building and are not exposed to the outside elements.

For the accessible hydrogen recombiner system piping :

1 . LSCS is not requesting relief from the accessible portion of the hydrogen recombiner system piping . The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code, Section XI, 2001 Edition through the 2003 Addenda, requires that system leakage test be conducted at nominal system operating pressure and temperature (i.e.,

atmospheric pressure at ambient temperature) . All accessible hydrogen recombiner system piping is pressure tested periodically as required by ASME Section XI (i .e ., at least three times each interval).

ATTACHMENT Response to Request for Additional Information Related to Relief Request 13R- 1 1

2. LSCS is not requesting relief from ASME Section XI for the accessible portion of the hydrogen recombiner system piping ; therefore, there is no proposed alternative system pressure test.

3. ASME Section XI, 2001 Edition through 2003 Addenda, does not require a 10-year system hydrostatic test. A system leakage test will be performed each inspection period with the same test pressure and temperature as described in item 1 above.

4. The test pressure and temperature during a typical refueling outage functional test (i.e ., operational surveillance) are atmospheric pressure and ambient temperature .

For the inaccessible (i .e., unit cross-tie piping) piping of the hydrogen recombiner system :

1 . The ASME B&PV Code, Section XI, 2001 Edition through the 2003 Addenda, requires that system leakage be conducted at nominal system operating pressure and temperature (i.e.,

atmospheric pressure at ambient temperature) . For the inaccessible (i .e., unit cross-tie piping) portion of the hydrogen recombiner system, relief is requested from the periodic test at nominal system operating pressure .

2. A pressure test on the inaccessible piping of the hydrogen recombiner system will be performed at the LSCS maximum peak accident pressure (Pa = 39.9 psig) at ambient temperature once during each inspection interval in lieu of every inspection period and by applying a soap bubble solution to all pipe welds.

3 . ASME Section XI, 2001 Edition through 2003 Addenda, does not require a 10-year system hydrostatic test . A pressure test will be performed once during each inspection interval as described in item 2 above .

4. The test pressure and temperature during a typical refueling outage functional test (i .e ., operational surveillance) are atmospheric pressure and ambient temperature . The operation functional test will not be credited for the inaccessible piping test; however, the refueling outage functional test (i .e., operational surveillance) will further ensure system operability and structural integrity.

Note that during the second ISI interval, no through wall leakage was detected during any of the periodic pressure tests of the accessible hydrogen recombiner piping system or during the once per interval testing of the inaccessible (i .e., unit cross-tie piping) piping .

Response Question B The service conditions (e.g., temperature, pressure, environment, time) of the hydrogen recombiner unit cross-tie piping are the same as the service conditions of the rest of the hydrogen recombiner system. During a refueling outage, the system is at atmospheric pressure and ambient temperature. At power operations, the system is isolated from the primary containment by primary containment isolation valves and therefore, the rest of the hydrogen recombiner piping is at reactor building pressure and temperature.