ML12109A278

E-Mail - Clarification Requested as a Result of Telecon on Friday, April 13, 2012 - Mur RAIs #12 and #13

ML12109A278
Person / Time
Site:	Braidwood
Issue date:	04/18/2012
From:	Mozafari B Plant Licensing Branch III
To:	Holden L, Byam T Exelon Corp
Mozafari B
References
Download: ML12109A278 (2)

Text

From: Mozafari, Brenda Sent: Wednesday, April 18, 2012 2:25 PM To: 'Leslie.Holden@exeloncorp.com'; timothy.byam@exeloncorp.com Cc: timothy.byam@exeloncorp.com

Subject:

Clarifications requested as a result of telecon on Friday April 13, 2012

Leslie, Below is a description of the clarification we are requesting for the MUR RAIs #12 and #13:

as discussed in our clarification call on April 13, 2012.

RAI-12: Unit 1 steam generator structural evaluation

1. Referring to Feb 20, 2012 letter, the 1st paragraph states that there are no changes to the calculated stress values because the MUR primary and secondary side temperature and pressure are enveloped by the original analysis. The 2nd paragraph states that a reconciliation analysis was performed due to difference in loads. These two statements are not consistent and the reason for the reconciliation analysis is not clear.

2. The summary tables provided in the response to RAI-12 represent values for the MUR conditions versus the values for the original power conditions instead of the current power level (it is expected that, from the review of LAR for 5% power uprate, the analysis of record was updated). It is difficult to discern the effects of MUR power uprate and identify those components that were affected (i.e., not bounded by the current analysis of record).

3. For some of the components in Table 12-1, the MUR stress intensity (SI) limits are larger than the original SI limits. As the code of record and methodology is unchanged, the reasons for these changes are not clear and no explanation is given in the response.

4. Aux. feedwater nozzle, which was a critical component for 5% stretch power uprate, is not listed in the summary tables included in the response to RAI-12. No explanation is given.

In summary, the response to RAI-12 should be clarified to reconcile MUR design input parameters against the current analysis of record, and for those components that are not bounded by the current analysis of record, it is expected that the maximum calculated stresses and cumulative fatigue usage factors are updated and included in the response to this RAI.

RAI-13

1. The response provides a maximum of 166.6 degrees SFP peak temperature.

Knowing that there is a possibility for concrete surface temperature to exceed 150 degrees (the response does not include the code of record and acceptance criteria),

166.6 degrees is an open item and may be inconsistent with the conclusions made in this response.

2. The response states that the existing calculations were reviewed (not revised) and concludes that the design basis code of record is satisfied. This implies that MUR

input parameters were bounded by the analysis of record and no revision to the existing design basis calculations was required. It is not clear how the MUR increase in SFP temperature has been reconciled.

In summary, the response to RAI-13 should provide further information to reconcile the MUR input parameters against the SFP design basis acceptance criteria specified in the design code of record. If the analyses of record for the SFP (including the SFP liner and spent fuel racks) are not bounding, then it is expected that a re-evaluation is performed and the analyses of record are updated.

I am aware that you are developing a response based on our call. The issues above are provided to assist in ensuring the response can be complete. Upon receipt, please call when you are able to support the final call on these RAIs so we can schedule the next call.

Brenda L. Mozafari Senior Project Manager Byron and Braidwood Plants 301-415-2020