ML13122A219

RAI, License Amendment Request Regarding Atmospheric Relative Concentration Values for Use in Control Room Envelope Radiological Dose Analysis

ML13122A219
Person / Time
Site:	McGuire, Mcguire
Issue date:	05/06/2013
From:	Jacqueline Thompson, James Kim Plant Licensing Branch II
To:	Capps S Duke Energy Carolinas
Boska J NRR/DORL/LPL2-1
References
TAC ME9716, TAC ME9717
Download: ML13122A219 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 May 6,2013 Mr. Steven D. Capps Vice President McGuire Nuclear Station Duke Energy Carolinas, LLC 12700 Hagers Ferry Road Huntersville, NC 28078

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION - MCGUIRE NUCLEAR STATION, UNITS 1 AND 2, LICENSE AMENDMENT REQUEST REGARDING ATMOSPHERIC RELATIVE CONCENTRATION VALUES FOR USE IN CONTROL ROOM ENVELOPE RADIOLOGICAL DOSE ANALYSIS (TAC NOS. ME9716 AND ME9717)

Dear Mr. Capps:

By application dated September 25, 2012, Duke Energy submitted a License Amendment Request (LAR) for the McGuire Nuclear Station, Units 1 and 2 (McGuire). The proposed LAR provides selected atmospheric relative concentration values for use in control room radiological dose analysis that were withdrawn during McGuire's request for full scope implementation of the Alternate Source Term (AST). McGuire received U. S. Nuclear Regulatory Commission (NRC) approval for full scope implementation of the AST on March 31,2009.

The NRC staff has reviewed the licensee's submittal and determined that additional information is needed in order to complete our review. The enclosed document describes this request for additional information (RAI). A response to this RAI is requested to be provided by June 14, 2013.

Sincerely, James Kim, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370

Enclosure:

RAI cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING LICENSE AMENDMENT REQUEST RELATED TO ATMOSPHERIC RELATIVE CONCENTRATION VALUES FOR USE IN CONTROL ROOM ENVELOPE RADIOLOGICAL DOSE ANALYSIS MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 By application dated September 25, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML12272A343), Duke Energy submitted a license amendment request (LAR) for the McGuire Nuclear Station, Units 1 and 2 (McGuire). The proposed LAR provides selected atmospheric relative concentration (X/Q) values for use in control room radiological dose analysis. These proposed X/Q values would replace those that were withdrawn during McGuire's request for full scope implementation of the alternate source term. The following request for additional information concerns information provided in Attachments 1 and 2 of the September 25,2012, LAR.

1. Table 1 of Attachment 1 provides inputs for 12 sets of control room X/Q values generated using the ARCON96 computer code. Tables 2 and 3 selectively list three sets of X/Q values each. Text adjacent to each table notes that the reported X/Q values reflect the maximum values from either Unit 1 or Unit 2, but does not explicitly name the unit associated with each set of X/Q values. U. S. Nuclear Regulatory Commission (NRC) staff has experienced some difficulty in understanding several of the X/Q sets provided in Tables 2 and 3 using the inputs in Table 1. Therefore, please provide the following information:

a) For each set of X/Q values in Tables 2 and 3, please identify the unit from which the release is assumed to occur.

b) Verify that the input values provided in Table 1 are those used to generate each set of X/Q values in Tables 2 and 3.

c) In addition to Tables 2 and 3, the September 25,2012, LAR provided two graphs of additional X/Q values derived from sensitivity studies performed by Duke Energy.

Please confirm that the LAR is seeking approval of all six sets and only the six sets of X/Q values listed in Tables 2 and 3.

d} Identify the inputs in Table 1 that apply to the main steam line break (MSLB) outboard X/Q values provided in Table 2.

e) Based on the inputs provided in Table 1, initial NRC estimates suggest that the inboard Doghouse X/Q values are larger than the outboard Doghouse X/Q values. Provide the basis for providing the cross unit outboard Doghouse X/Q values in Table 3.

Enclosure

-2 f) Please confirm that the horizontal length of the louvers on the south walls of the Doghouses is at least 8.88 meters long, as implied by the initial Oy input of 1.48 meters provided in Table 1. Further, confirm that it is reasonable to assume that the release rate from the building interior is essentially equally dispersed over the entire length of the louver because release characteristics, mixing, transport, and the arrangement of internal components within the Doghouses facilitate such an assumption.

g) With regard to the louvers on the south walls of the Doghouses, Section 2.2 of Attachment 1 states that "the release is assumed to originate from a line projected perpendicular to the line of sight between the receptor and the building surface closest to the control room intake." Attachment 2 provides a simplified drawing showing plant structures and the control room intakes. Please highlight the assumed release locations on Attachment 2 and discuss if the direction, distance, and height inputs are based upon straight line or "taut string" estimates, as discussed in Regulatory Guide 1.194, Atmospheric Relative Concentrations for Control Room Radiological Habitability Assessments at Nuclear Power Plants.

2. Figure 2 of Attachment 1 is a graph of the Unit 1 inboard MSLB variable receptor to source angle sensitivity. Please confirm that the plotted values are distances from the closest release point along the main steam line and do not represent numeric distances of each point from the control room intake.

ML13122A219 OFFICE NRR/LPL2-lIPM NRR/LPL2-1/LA NRR/LPL2-1/BC NAME JKim SFigueroa RPascarelli DATE 05/06/13 05106/13 05/06/13