ML14087A210

Summary of 3/25/14 Verbal Relief Telephone Conference, Relief Request I3R-16, Temporary Non-Code Repair of the Train a Component Cooling Water Heat Exchanger to Control ESW Leakage, Third 10-Year Inservice Inspection Interval

ML14087A210
Person / Time
Site:	Callaway
Issue date:	04/08/2014
From:	Lyon C Plant Licensing Branch IV
To:	Union Electric Co
Lyon C
References
TAC MF3650
Download: ML14087A210 (3)

Text

LICENSEE: Union Electric Company FACILITY: Callaway Plant, Unit 1

SUMMARY

OF TELEPHONE CONFERENCE ON MARCH 25, 2014, TO GRANT VERBAL RELIEF FOR 13R-16 (TAC NO. MF3650)

This memorandum summarizes the telephone discussion on March 25, 2014, between the U.S. Nuclear Regulatory Commission (NRC) staff and Ameren Missouri (dba Union Electric Company, the licensee) staff regarding the licensee's request for relief 13R-16 for Callaway Plant. Participants in the discussion included T. Elwood, J. Kovar, and M. Hoehn (licensee),

and C. Fairbanks, M. Markley, P. Purtscher, and F. Lyon (NRC).

By letter dated March 19, 2014 (ADAMS Accession No. ML14079A529), the licensee requested NRC approval to implement an alternative to the requirements in IWA-4000 of the 1998 Edition with the 2000 Addenda of Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) regarding repair of the heat exchanger. The alternative was requested under the provisions of paragraph 50.55a(a)(3)(ii) of Title 10 of the Code of Federal Regulations (10 CFR). The NRC staff evaluated the licensee's request for relief 13R-16, and clarifying information provided in a conference call with the licensee on March 24, 2014 (ADAMS Accession No. ML14084A136), as summarized below.

On October 14, 2013, during routine plant operation, the licensee discovered a leak from the essential service water (ESW) side of Train "A" Component Cooling Water (CCW) heat exchanger, EEG01A. The licensee attributed the leak to pitting corrosion at a localized area of coating damage on the inside of the heat exchanger. Implementing an ASME Code-required repair before the next refueling outage would require draining ESW from the heat exchanger, making one train of CCW and one train of ESW inoperable.

The bounding size of the flaw was conservatively determined by ultrasonic testing (UT) by the licensee to be a pit with a % inch diameter. The licensee proposed to use ASME Code Case N-705 to characterize and evaluate the structural integrity of the system. Applying Code Case N-705, the licensee has demonstrated that it can continue to operate until the next refueling outage in October 2014. Given the postulated ESW leakage, a margin still exists between this worst-case bounding condition and the requirements for ESW system operability.

During the coming summer months, the temperature of the ESW system will increase and, without a repair, the margin for operability would be reduced. The licensee proposes to install a temporary mechanical clamping device, which would reduce assumed leakage and would be able to be credited as a pressure boundary in the area of the leak, in order to increase the margin of operability. The design of the clamping device follows the requirements of IWA-4133.

The licensee has used conservative assumptions regarding the flaw size, stress state, and potential for flaw growth until the next refueling outage, and determined that the postulated flaw

would meet the structural margins required by the Code Case N-705 under all normal, upset, emergency, and faulted conditions. Furthermore, the licensee has committed to daily visual inspection for leakage and additional UT inspections every 3 months to demonstrate that the alternative still meets the Code Case N-705 requirements for monitoring and examination of the flaw. The licensee requested verbal relief in order to install the temporary clamping device during the scheduled ESW Train "A" maintenance outage the week of March 24, 2014.

The NRC staff has completed its review of the information provided by the licensee and the requirements for use of Code Case N-705. The staff concludes that requiring the licensee to make a permanent Code-required repair to the leaking CCW heat exchanger EEG01A before the next refueling outage would create a hardship without a compensating increase in level of quality and safety, based on the potential risks associated with unit cycling and any emergent equipment issues incurred during shutdown and startup evolutions.

Therefore, in accordance with 10 CFR 50.55a(a)(3)(ii), based on the hardship without a compensating increase in the level of quality and safety, the NRC staff, with the concurrence of M. Markley, NRR/DORU/LPL4-1/BC, and C. Fairbanks, NRR/DE/EVIB/BC(A), grants request for relief 13R-16 for Callaway Plant, for the period not to exceed startup from the fall 2014 refueling outage. The staff's final safety evaluation will be provided as a matter of routine by separate correspondence.

If you have any questions, please contact me at (301) 415-2296 or by e-mail at fred.lyon@nrc.gov.

Carl F. Lyon, Project Manager Plant Licensing Branch IV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-483 cc: Distribution via Listserv

ML14087A210 OFFICE NRR/DORULPL4-1/PM NRR/DORLILPL4-1/LA NRR/DORLILPL4-1/BC NRR/DORL/LPL4-1/PM NAME Flyon JBurkhardt MMarkley Flyon DATE 4/7/14 4/7/14 4/8/14 4/8/14