South Texas Emergency CRDM Admendment ???

 The UCS take on it.

D6 Control Rod Drive Mechanism (CRDM) housing without the drive rod

Resource

From: Regner, Lisa

Sent: Tuesday, December 08, 2015 8:02 PM

To: Brost, Wendy (webrost@STPEGS.COM); cralbury@stpegs.com

Cc: Sterling, Lance (lsterling@STPEGS.COM); Michael Murray; Richards, Drew

(amrichards@STPEGS.COM) Subject: DRAFT Request for Additional Information - Emergency Amendment
Importance: High

Wendy, Charlie,

Below are the draft questions that the staff needs answered for us to complete our review of your Emergency Amendment submitted on December 3. As discussed with you on December 8, your acceptable response is requested within 24 hours, for the staff to make its decision by December 11, as requested in your December 3 submittal.

If you have any questions, please feel free to contact me.

Thank you,

Lisa

1. Confirm that the most positive moderator density coefficient remains bounding for the moderator
feedback effects assumed in Chapter 15.1.5, ‘Spectrum of Steam System Piping Failures Inside and
Outside Containment

2. For the Departure from Nucleate Boiling analysis related to Steam Line Break, provide additional
information on why the Departure from Nucleate Boiling Ratio changed from 3.011 to 1.811.

3. Provide the impacts to the reactor protective system from the modifications to the Digital Rod Position Indication system associated with the removal of control rod D6.

4. Provide the impacts to operator actions or emergency operating procedures as a result of the removal of control rod D6.

5. In order for the staff to assess the potential of the proposed flow restrictor generating loose parts,
provide a description of any relevant design features of the flow restrictor, and justify how the thermal expansion of the flow restrictor and its component parts has been addressed.

6. In order for the staff to verify the structural adequacy of the D6 Control Rod Drive Mechanism (CRDM) housing without the drive rod, when subjected to Loss of Cooling Accident or seismic excitations, provide a description of relevant analyses that were performed to model the CRDM without the mass of  the drive rod.

Lisa M Regner, Sr. Project Manager, Branch LPLIV-1

Division of Operating Reactor Licensing

Office of Nuclear Reactor Regulation