ML13190A255

NRC Internet Event Briefing - Palisades Safety Injection Refueling Water Tank (SIRWT) Leak Repair and Inspections

ML13190A255
Person / Time
Site:	Palisades
Issue date:	07/16/2013
From:	NRC/RGN-III
To:
References
Download: ML13190A255 (17)

Text

NRC Internet Event Briefing Palisades SIRWT Leak Repair and Inspections July 16, 2013 1

Welcome Jack Giessner Branch Chief NRC Region III 2

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 3

Meeting Agenda

• Meeting Purpose

• SIRWT leak, repairs and examinations

• NRC inspections

• Q&A Session

• Closing Remarks 4

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)

M Nozzle F Nozzle leak

• Image for demonstration purposes only 6

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

Questions 15

Meeting Closure Jack Giessner Branch Chief NRC Region III 16

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