ML13190A255
| ML13190A255 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 07/16/2013 |
| From: | NRC/RGN-III |
| To: | |
| References | |
| Download: ML13190A255 (17) | |
Text
1 NRC Internet Event Briefing Palisades SIRWT Leak Repair and Inspections July 16, 2013
2 Welcome Jack Giessner Branch Chief NRC Region III
3 Introductions - NRC
- Jack Giessner, Chief, Branch 4 (Presenter)
- Mel Holmberg, Senior Reactor Inspector, Branch 1
- David Alley, Senior Materials Engineer, NRR
- Richard Conatser, Health Physicist, NRR
- Thomas Taylor, Senior Resident Inspector, Palisades
4 Meeting Agenda
- Meeting Purpose
- SIRWT leak, repairs and examinations
- NRC inspections
- Q&A Session
- Closing Remarks
Meeting Purpose
- Discuss the NRCs response to the recent leak from the safety injection refueling water tank at Palisades
- Answer questions from the public 5
Safety Injection Refueling Water Tank (SIRWT)
- Image for demonstration purposes only 6
M Nozzle F Nozzle leak
What happened with the SIRWT?
Palisades plant shutdown on May 5, 2013, due to observed SIRWT leakage of ~90 gallons per day (gpd)
Exceeded the 38 gpd limit to shut down established by NRC's confirmatory action letter (CAL EA 12-155; ML12199A409)
~80 gallons of low radioactivity water spread onto the roof, down roof drains, into drains that go to Lake Michigan Released radioactivity to Lake Michigan (0.000002 rem) is well below regulatory limits (.1 rem/year) and did not impact the safety of plant workers or the public The sand samples taken near the plant discharge indicated no impact to the public - independently verified by NRC 7
What happened with the SIRWT?
Licensee determined the root cause of the SIRWT leak to be a failure of a nozzle weld resulting from an inadequate fusion at the weld root, i.e., a poorly performed weld from 2012 8
NRC Inspections
- Around 12 inspectors were involved in NRC review of code repair, structural and non-destructive examinations of the SIRWT
- The NRC inspectors observed work activities inside the tank
- NRC reviewed the SIRWT root cause report and design change evaluation to ensure the tank performs its required safety function
- Resident inspectors are periodically inspecting the SIRWT roof for leakage 9
SIRWT Repair
- The NRC reviewed the following actions by the Licensee:
- Tank bottom replacement
- Replacement of all welds associated with the floor inside the tank
- Nozzle replacement
- Installed a layer of fiber board between the concrete slab and new aluminum plating 10
SIRWT Examinations
- The NRC reviewed the following actions by the Licensee :
- Welding workers got hands-on training on the aluminum welds
- Completed a range of tests on the new plate and welds 11
Main Control Room Leak
- On June 4, 2013, a few drops of water from the control room ceiling dripped onto one of the panels
- The leak originated from the M nozzle during tank repairs
- The licensee established a catch device to capture the leakage
- The leakage lasted for ~4 hours at 3 drops per minute
- The resident inspector walked down the control room and verified there was no impact to any equipment
- The licensee has to repair the concrete ceiling in accordance with the NRC Confirmatory Action Letter (CAL) 12
Ongoing Actions
- In accordance with the NRC CAL, the licensee is required to:
- Continue inspections of the concrete support structure above the control room, control room hallway, and the concrete support structure ceiling
- Repair the control room ceiling before the next refueling outage
- Ongoing inspections of the tank by the licensee and NRC show no leakage
- Follow-up NRC inspections will be conducted on site
- Report with NRC conclusions will be issued 13
Summary
- NRC reviewed licensees work related to repairs and examinations of the SIRW tank:
- root cause
- design change evaluation
- tank repairs
- Tank will be monitored for leakage
- The SIRWT is performing its safety function and the plant is safe 14
15 Questions
16 Meeting Closure Jack Giessner Branch Chief NRC Region III
Meeting Contacts For Follow-up Questions - Contact the NRC Region III Office of Public Affairs:
Viktoria Mitlyng / Prema Chandrathil Tel: (630) 829-9500 OPA3@nrc.gov 17