ML090150014

County 1 and LaSalle County 2 -Follow-up RAIs Regarding LPRM LAR (MD9414 and MD9415)

ML090150014
Person / Time
Site:	LaSalle
Issue date:	01/15/2009
From:	Sands S Plant Licensing Branch III
To:	Mackellar A, Nicely K Exelon Corp
SAnds, SP, NRR/DLPM/LPD III-2, 415-3154
References
TAC MD9414, TAC MD9415
Download: ML090150014 (1)

Text

From: Stephen Sands Sent: Thursday, January 15, 2009 6:53 AM To: 'ken.nicely@exeloncorp.com'; 'Alison.MacKellar@exeloncorp.com'

Subject:

Follow-up questions regarding LRPM - LAR Importance: High Ken/Alison:

This e-mail is to inform Exelon Generation Company (Exelon) that the questions below are being placed in the Agencywide Document Access and Management System (ADAMS) as an official record transmitting additional information the NRC staff is requesting. In order for the NRC staff to continue with the review, it is requested that your responses be sent within 30 days from this e-mail transmitting the questions. The questions below were supplied by the NRC technical review staff after reviewing the initial submittal, dated July 25, 2008, and your responses to the RAI dated 10/31/2008.

1. The Exelon response to RAI 1.3 states that the uncertainty analysis was done for a fixed decay factor of -0,092 for both units." By choosing a fixed sensitivity, one expects to maximize the uncertainty in the predicted response.

Provide the results of the uncertainty analysis using the values of the decay constants specific to the LPRM detectors at the LSCS and demonstrate that the uncertainties based on the fixed decay factor bound that based on the LSCC specific decay factors.

The information should include the uncertainties (relative standard deviations) for Units 1 and 2 for exposure values of 1000 MWd/MTU, 2500 MWd/MTU, and 2675 MWd/MTU in a format consistent with Tables 6 and 7.

2. The RAI 1.4 response states that the accumulated exposure values were obtained from the core monitor system (i.e., POWERPLEX-II and POWERPLX-III. The RAI 1.3 response indicates that the actual value currently in use for core monitoring is -

0.1189. The sensitivity analytical results included in Table 6 and 7 show that for the cases using the decay factor -0.1189 are 0.92 percent and 1.03 percent for the nominal exposure values of 2500 MWd/MTU, and 2675 MWd/MTU, respectively. As indicated in the RAI 1.3 and 1.4 responses, both values of the uncertainty, 0.92 percent and 1.03 percent, are greater than the allowable uncertainty of 0.9 percent used in the MCPR safety limit analysis. Based on the results of the uncertainty analysis discussed above, justify that the proposed extension of the LRPM calibration interval from 1000 EFPH to 200 EFPH is acceptable.

3. Since the accumulated exposure values were obtained from the core monitor system with the decay factor of -.0.1189 used in the POWERPLX software, provide a discussion and analysis to justify the adequacy of use of the accumulated exposure values in the uncertainty analysis for the cases with the decay values of the LSCS specific detectors, and fixed decay values of -0.80, -0.92, -0.10, and -0.1189 shown in Table 6 and 7.

Stephen Sands Division of Operating Reactors Clinton & LaSalle Project Manager Licensing Project Branch 3-2

Phone: 301-415-3154 E-mail: Stephen.Sands@nrc.gov E-mail Properties Mail Envelope Properties (B4ECC0E252653F48B3F57C3B833465E80DBCF76273)

Subject:

Follow-up questions regarding LRPM - LAR Sent Date: 1/15/2009 6:52:52 AM Received Date: 1/15/2009 6:52:00 AM From: Stephen Sands Created By: Stephen.Sands@nrc.gov Recipients:

ken.nicely@exeloncorp.com ('ken.nicely@exeloncorp.com')

Tracking Status: None Alison.MacKellar@exeloncorp.com ('Alison.MacKellar@exeloncorp.com')

Tracking Status: None Post Office:

HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 8436 1/15/2009 Options Expiration Date:

Priority: olImportanceHigh ReplyRequested: False Return Notification: False Sensitivity: olNormal Recipients received: