ML12005A038

E-mail from M. Franke, Region II to G. Mccoy, Region II; AIT 9/2Update

ML12005A038
Person / Time
Site:	North Anna
Issue date:	09/02/2011
From:	Mark Franke NRC/RGN-II
To:	Gerald Mccoy NRC/RGN-II
References
FOIA/PA-2011-0357
Download: ML12005A038 (2)

Text

From: Franke. Mark To: McCoy. Gerald

Subject:

AIT 9/2 update Date: Friday, September 02, 2011 9:38:00 AM NAPS AIT update 9/2 Plant Status Both Units remain in Mode 5, cold shutdown.

Charter Item Comments (new items are highlighted)

1) Sequence of Events -in progress (50%); no new items

2) Data to determine seismic strength - Scratch plate data and preliminary process data still show that DBE was exceeded. The licensee now expects a final report by 9/9. Issues with seismic instrument installation, including wiring polarity andý possible orientation problems, are under review.

3) Rx trips - The U1 and U2 reactor trips appear to have been initiated by a reactor protection system neutron rate flux trips that occurred prior to LOOP. The licensee is conducting a root cause evaluation to determine the cause of flux trip signal -

some considerations include core barrel movement, NI movement in wells, and rod movement or rod control malfunctions.

4) EDG Performance -

2H EDG - An incorrectly installed gasket from 2009 appears to have contributed to the JW leak. Issues affecting 2H EDG recovery time during the event included: (1) the EDG was started for a maintenance run with some petcocks inadvertently left open, and (2) the EDG experienced an exhaust system gasket leak (small leak) during a PMT run from a new gasket installed during the repair.

1J EDG - While the EDG performed its function during the event, frequency oscillations exceeding TS limits were observed.

5) Electrical System Performance - AIT is conducting walkdowns, including over breaker 100 cabinets, and is sorting thru a number of miscellaneous issues and anomalies; no significant issues at this time

6) On-Shift HU Performance- reviewing records and conducting interviews with all operators that were on-shift when the event occurred - 70% complete; SBO EDG manual sync switch key location issues affected SBO EDG response time; no evidence of significant performance issues so far

7) Plant parameter review - licensee has completed interior walkdowns of all Unit 1 Class 1 structures (50% complete overall because exterior walkdowns are remaining) and continues with Unit 2 (30 % complete overall). AIT structural engineers completed U1 containment walkdown, including the PORV, and confirmed licensee observations. No significant issues were noted. U2 containment walkdown is today.

8) Operability - AIT completed review of PZR PORV OD and have no significant concerns with the licensee's evaluation. The AIT will walkdown the U2 PORV in containment today.

9) Plans for Restart - Licensee has provided the AIT with a very rough sketch of restart activities. Major activity areas are (1) Data Collection and Analysis; (2) Re-;

start Assessment and Licensing Review; (3) Plant Restart and Operation; and (4)

Required Follow-on Activities. This plan is still in development and no restart date.

is identified.

10) ISFSI - team walkdown complete; no immediate safety concerns noted; team noted evidence of possible movement of NUHOMS units; Licensee identified in yesterday's post seismic walkdown that two initial TN32.spacing measurements were either incorrect, or that some casks may have moved slightly again due to aftershocks. Both spacing measurement deltas were 0.5". AIT wi !mo nitorn licensee actions.

11) Collect Risk Data - continuing; no new issues

12) Potential Generic Issues - (1) Seismic panel power supply pedigree and EAL reliance, and (2) seismic monitors are located on the structures and not located on the free surface in the free field; therefore the recorded ground motion is not a good indicator for determining whether OBE and DBE was exceeded.

URLs (1) 2H EDG JW leak; (2) 1J EDG Frequency Oscillations; (3) Seismic Panel Power; (4)

Seismic Instrument Installation Recommendations AIT remains the appropriate level of agency response.

AIT scope remains appropriate and AIT is on-track to complete current scope by the original estimated date of 9/16.

AIT has not identified immediate safety concerns for ISFSI. Considering the strength of the seismic activity recorded at nearby plant structures, additional follow-up by NMSS may be warranted to further review the seismic design of the casks and any potential impact.