ML13263A168

Request for Additional Information, Closure of Option 2 to Address In-Vessel Mitigative Measures for Potential In-Vessel Blockage; Related to Generic Safety Issue 191

ML13263A168
Person / Time
Site:	Callaway
Issue date:	09/23/2013
From:	Lyon C Plant Licensing Branch IV
To:	Heflin A Union Electric Co
Lyon C
References
TAC MC4671
Download: ML13263A168 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 23,2013 Mr. Adam C. Heflin Senior Vice President and Chief Nuclear Officer Union Electric Company P.O. Box 620 Fulton, MO 65251

SUBJECT:

CALLAWAY PLANT, UNIT 1 - REQUEST FOR ADDITIONAL INFORMATION RE: CLOSURE OF OPTION 2 TO ADDRESS IN-VESSEL MITIGATIVE MEASURES FOR POTENTIAL IN-VESSEL BLOCKAGE (TAC NO. MC4671)

Dear Mr. Heflin:

In its letter dated May 16, 2013 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13136A290), Union Electric Company (dba Ameren Missouri, the licensee), provided the U.S. Nuclear Regulatory Commission (NRC) with its intended path forward for the resolution of Generic Safety Issue (GSI)-191, "Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance," for Callaway Plant, Unit 1 (Callaway). The licensee stated that Callaway would be following the Option 2 risk-informed approach, partially due to high fiber levels in containment.

The DecelTIber 14, 2012, Staff Requirements Memorandum on SECY-12-0093, "Closure Options for [GSI-191]" (ADAMS Accession No. ML12349A378), describes three closure options that licensees can follow to resolve GSI-191. The NRC staff has determined that additional information, as requested in the enclosure, is needed from licensees to complete the review of Option 2 plants, including Callaway, which did not address mitigative measures for potential in-vessel blockage.

A. Heflin -2 Please provide a response to the enclosed request for additional information by October 31, 2013. If circumstances result in the need to revise the requested response date, please contact me at 301-415-2296 or via e-mail at Fred.Lyon@nrc.gov.

Sincerely, Carl F. Lyon, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-483

Enclosure:

As stated cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION CLOSURE OF OPTION 2 FOR GENERIC SAFETY ISSUE (GSI}-191 UNION ELECTRIC COMPANY CALLAWAY PLANT, UNIT 1 DOCKET NO. 50-483 The December 14,2012, Staff Requirements Memorandum on SECY-12-0093, "Closure Options for Generic Safety Issue (GSI)-191, "Assessment of Debris Accumulation on Pressurized-Water Reactor Sump Performance" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12349A378), describes three closure options that licensees can follow to resolve GSI-191. The U.S. Nuclear Regulatory Commission (NRC) staff has determined that additional information is needed to complete its review of Option 2 plants, including Callaway Plant, which did not address mitigative measures for potential in-vessel blockage.

In its letter dated May 16, 2013 (ADAMS Accession No. ML13136A290), Union Electric Company (dba Ameren Missouri, the licensee), provided the NRC with its intended path forward for the resolution of GSI-191. The licensee stated that Callaway Plant would be following the Option 2 risk-informed approach, partially due to high fiber levels in containment. The licensee also referenced a Nuclear Energy Institute (NEI) letter dated May 4, 2012 (ADAMS Accession No. ML12142A316), as one of the documents providing guidance on the contents of the licensee's submittal as a path forward. The NRC staff noted that the May 4, 2012, NElletter stated that licensees that do not meet very low in-vessel debris limits would provide, as part of the intended path forward, mitigative measures to reduce risk while taking actions to finalize the resolution of Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" (ADAMS Accession No. ML042360586). The May 16, 2013, letter did not identify that the licensee had implemented, or identified for future implementation, any mitigative measures to deal with the potential for in-vessel blockage.

The NRC staff has determined that the following request for additional information is needed to complete the review of Option 2 plants, including Callaway Plant, which did not address mitigative measures for potential in-vessel blockage:

Please provide the mitigative measures, in place or planned, to deal with potential in-vessel blockage at Callaway Plant. If all mitigative measures have not been implemented, please provide the schedule for implementing them.

Enclosure

ML13263A168 *email dated OFFICE NRRlDORLJLPL4IPM NRRlDORUlPl4/LA NRRlDPRlPGCB/BC(A) NRRlDORLJlPl4/BC NRRlDORLJlPl4IPM NAME Flyon JBurkhardt SSluchell* MMarkley Flyon DATE 9123/13 9/23113 9/19/13 9/23/13 9/23113