ML052130174

Request for Additional Information Related to EPU and Steam Dryers

ML052130174
Person / Time
Site:	Dresden
Issue date:	12/29/2004
From:	Banerjee M NRC/NRR/DLPM/LPD2
To:	Nicely K, Roddey T Exelon Corp
References
Download: ML052130174 (3)

Text

[ Marshanda White-Pyle - Dresden Units 2and 3 - Reque r Additional Information Related to EPU and Steam Dryers Page 1 From:

Maitri Banerjee To:

Ken.nicelyaexeloncorp.com; Thomas.roddeyeexeloncorp.com Date:

12/29/04 4:44PM

Subject:

Dresden Units 2 and 3 - Request for Additional Information Related to EPU and Steam Dryers The NRC staff review of Exelon Generation company, LLC (EGC)'s December 10, 2004 letter resulted in some questions. I am sending you these questions to make sure they are addressed before or during the February 2005 meeting between EGC and the NRC. Some of these questions relate to the strain gauges.

We can discuss them during the proposed phone call for next week. If you have any questions or need clarifications, please let me know. I will try to schedule a phone call with the NRC technical reviewer early next week, if needed.

Questions:

Please provide answers to the following questions regarding plant performance following restart of Dresden Units 2 and 3 and return to EPU operation subsequent to the recently completed outages:

1. It is our understanding that three of the eight strain gauge sensors recently installed on the main steam lines at Dresden Unit 3 have failed. Please provide the cause of the failure.

2. Please discuss the impact of the loss of data from the three failed strain gauges at Dresden Unit 3, and how the development of a reliable and accurate prediction of steam dryer loads by the acoustic circuit model will be affected by the absence of data from those sensors. Please include a discussion of the reliability of the steam dryer load prediction if data from sensors in Dresden Unit 2 are applied in the Dresden Unit 3 steam dryer analysis.

3. Recently, when eight of 30 accelerometers installed in Quad Cities Unit 1 were providing suspect data, EGC returned the unit to a hot shutdown condition to repair/replace the suspect accelerometers. Please explain why a similar approach was not followed to repair/replace the inoperable main steam line strain gauge sensors in Dresden Unit 3.

4. Commitment No. 10 in EGC's letter dated December 10, 2004, specifies that a general visual inspection of the reactor vessel internals, and the steam and feedwater systems (including the most susceptible components) will be performed at Dresden Unit 2 during the fall 2005 refueling outage based on the EPU vulnerability evaluation. Commitment No. 9 of EGC's May 12, 2004 letter to the NRC made a similar commitment for all units of Dresden and Quad Cities. The December 10 letter states that the EPU vulnerability evaluation of plant equipment was implemented at Dresden Unit 3 during the fall 2004 refueling outage. Was the general visual inspection indicated in Commitment No. 10 fully completed at Dresden Unit 3 during the fall 2004 refueling outage?

5. Please discuss the information regarding plant performance related to EPU operation that has been obtained from plant walkdowns, and from data collected regarding equipment vibration and other loadings, during power ascension and EPU operation at Dresden Units 2 and 3 since the recently completed outages. Please include a discussion of any equipment performance problems attributable to EPU operation that occurred during the power ascension and EPU operation at the Dresden units.

6. To the extent apparent at this time, please discuss whether the data collected from the main steam line strain gauges have been consistent with expectations of lower steam dryer loads at Dresden compared to Quad Cities.

Please also let me know if you do not consider the requested information to be necessary for regulatory decision-making.

Maitri Banerjee, PE Sr. Project Manager, PDI11-2

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MarhadaWhi~te -Pyle - Dresden Units 2 and 3 - Request for Additional Information Related to EPU and Steam Dryer~s Page~ 2 Division of Licensing Project Management Office of Nuclear Reactor Regulation CC:

David Terao; Gene Suh; Mark Ring; Thomas Scarbrough

Mail Envelope Properties (41D32538.F77: 8: 21450)

Subject:

Dresden Units 2 and 3 - Request for Additional Information Related to EPU and Steam Dryers Creation Date:

12/29/04 4:44PM From:

Maitri Banerjee Created By:

MXB(nrc.gov Recipients exeloncorp.com ken.nicely (Ken.nicely~exeloncorp.com)

Thomas.Roddey (Thomas.roddey~exeloncorp.c nrc.gov chpo.CHDO MAR CC (Mark Ring) nrc.gov owf2_po.OWFNDO DXT CC (David Terao)

TGS CC (Thomas Scarbrough) nrc.gov owf4_o.OWFNDO GYS CC (Gene Suh)

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