ML023530645

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Meeting Slides Used by First Energy Nuclear Operating Co Re Davis-Besse Reactor Vessel Incore Monitoring Instrumentation Nozzles, Inspection & Potential for Leakage
ML023530645
Person / Time
Site: Davis Besse Cleveland Electric icon.png
Issue date: 11/26/2002
From: Hopkins J
NRC/NRR/DLPM/LPD3
To:
Hopkins J, NRR/DLPM, 301-415-3027
References
Download: ML023530645 (32)
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1 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Davis-Besse Nuclear Power Station Reactor Vessel Incore Nozzles

2 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Opening Remarks..............Gary Leidich Reactor Vessel Incore Nozzles. Bob Schrauder

  • Incore Nozzle Configuration
  • Recent Inspection and Evaluation at Davis-Besse
  • Actions Prior to Returning the Plant to Service
  • Contingency Repair Concept
  • FLÜS Online Leak Monitoring System Closing Comments.. Gary Leidich

3 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Gary Leidich Executive Vice President - FENOC

4 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Brief the NRC Staff on the status of the Davis-Besse Reactor Vessel Incore Monitoring Instrumentation Nozzles and future plans
  • Obtain NRC comments on Davis-Besse approach

5 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 CEO of FirstEnergy has set the standard of returning Davis-Besse back to service in a safe and reliable manner.

We must do the job right the first time and regain the confidence of our customers, regulators, and investors in our nuclear program.

We are committed to meeting this challenge.

6 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Reactor Head Reactor Head Resolution Plan Resolution Plan Bob Schrauder Bob Schrauder Program Compliance Program Compliance Plan Plan Jim Powers Jim Powers Containment Health Containment Health Assurance Plan Assurance Plan Randy Fast Randy Fast Restart Test Plan Restart Test Plan Randy Fast Randy Fast Management and Management and Human Performance Human Performance Excellence Plan Excellence Plan Lew Myers Lew Myers System Health System Health Assurance Plan Assurance Plan Jim Powers Jim Powers Restart Action Plan Restart Action Plan Lew Lew Myers Myers Restart Overview Panel Restart Overview Panel Return to Service Plan Return to Service Plan

7 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Inspection of the Incore Nozzles is part of the Containment Health Assurance Building Block in the Davis-Besse Return to Service Plan

8 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Bob Schrauder Director - Support Services

9 Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Babcock & Wilcox reactor vessel has 52 Incore Nozzles
  • Incore nozzles are ~ 1 inch in diameter
  • Original incore nozzles fabricated from Alloy 600 material
  • Welds - Alloy 182 (stress relieved)
  • Incore nozzles modified following Oconee 1 1972 Hot Functional Testing Failure Configuration Incore Nozzles at Bottom of Reactor Vessel (Post-cleaning)

1 0

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Repair in Process Completed Repair

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Visual inspections of the incore nozzles have not been routinely conducted in United States plants
  • Inspections/testing of incore nozzles at 13 French plants have not discovered cracking or leaking Incore Nozzles

1 2

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 B&W Current Nozzle Configuration EDF Nozzle Configuration Original Configuration

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Visual Inspections performed as part of the Extent of Condition Program Inspection of Bottom of Reactor Vessel

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Inspection results:

- Boron and rust deposit trails were observed on the sides and bottom of the reactor vessel

- Similar deposits observed on several incore nozzles

- Tape remnants and residue observed on incore nozzles

- No build-up of boric acid or corrosion products on top of insulation

- No evidence of wastage on bottom of reactor vessel Bottom of Reactor Vessel

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Incore Nozzle #42 Incore Nozzle #45

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 AREAS:

  • Reactor vessel flow trail and incore nozzle deposits OBJECTIVE:
  • Determine through chemical analysis whether flow trails and incore nozzle deposits had common source SAMPLE POPULATION:
  • 2 from flow trails observed on under reactor vessel sides
  • 12 from incore nozzles
  • Analysis by Framatome-ANP Incore Nozzle #45 Bottom of Reactor Vessel

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Sample locations ( ) chosen were nozzles 1

7 3

13 14 18 23 27 35 45 48 46

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Boron and Lithium were higher at several incore nozzle locations than in flow trails and more comparable with previously analyzed upper head deposit samples (shown next slide)

However, the lack of activity associated with these species did not support reactor coolant as the source

  • Cobalt (Co60) and Iron (Fe59) were higher in the flow trails than at the incore nozzle locations
  • Inconsistent concentration gradients along possible flow trail paths

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 NW Rust Trail SE Boric Acid Trail Nozzle #1 Nozzle #3 Nozzle #7 Nozzle #13 Nozzle #14 Nozzle #18 Nozzle #23 Nozzle #27 Nozzle #35 Nozzle #45 Nozzle #46 Nozzle #48 0

5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 ppm Comparison of Normalized Boron and Lithium Concentrations (Flow trails at bottom of reactor head and incore nozzle deposits)

Li B

2 0

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Conclusion From the results of the analysis, it is inconclusive whether the flow trails at the bottom of the reactor head and nozzle deposits had a common source

2 1

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • FENOC and Framatome-ANP developed inspection plan
  • Bottom of reactor vessel thoroughly cleaned 9/2002
  • Planned visual inspections prior to startup:

- Raise Reactor Coolant System to normal operating pressure and temperature (hold for 3-7 days)

- Potential use of hot optics (visual inspection aid)

- Lower temperature and pressure

- Perform bare metal reactor vessel visual inspection

- Perform bare metal reactor vessel visual inspection during the next scheduled outage

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 0.001 0.010 0.100 1.000 10.000 100.000 1000.000 1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 Leakage Rate (gpm)

Boric Acid Deposits (in3) 35 Day 28 Day 21 Day 14 Day 10 Day 7 Day 3 Day 1 Day FLUES OPTION 1 FLUES OPTION 2

?

Boron Deposit Rate For 2000 ppm Boron Reactor Coolant Leakage (Unchoked Flow) 100% Deposition Rate For a Given Number of Days

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Inspections will be sufficient to detect leakage
  • Absence of boric acid will confirm that the deposits found in in 2002 were not from incore nozzle leaks

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Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Program Objectives

- Measure leak rate as a function of simulated and/or actual flaw geometry

  • Benchmark analytical models for bounding leak rate calculations
  • Identify residue deposit chemistry and any volatile chemicals that exit the crevice
  • Investigate effect of annulus on leakage rates

- Verify methods for detecting very small leaks

  • Visible evidence of boron residue
  • In-situ monitoring techniques

2 5

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Framatome-ANP Hot Leak Test Facility will be used to provide primary fluid:

- Tc = 558º F; p = 2200 psig

- Primary chemistry (boron &

lithium concentration)

Mockup assembly will be connected to existing high temperature/ high pressure supply system Leak rates measured from 10-6 to 0.25 gpm

2 6

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Mockup is being designed and built to measure leak rates through simulated (SCC) flaws
  • Leak rate bounding tests will be conducted for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> each
  • Final test with a selected leak rate will be run for 5 days

2 7

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Insert mechanical plug and cut existing incore nozzle
  • Deposit 1/2 - 5/8 weld pad
  • Bore out incore nozzle remnant into reactor vessel to 1 maximum depth
  • Fit-up replacement nozzle and complete new weld
  • Remove mechanical plug 1/16" - 1/8" prior to welding PT New Alloy 690 Nozzle New SST Safe End

2 8

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • If repairs are necessary, a meeting to discuss final design will be held with the NRC
  • 10CFR50.55a alternative code (ASME Code Section XI) requests will be necessary to permit implementation of repairs
  • Alternative code request will be similar to those submitted to NRC for the repair of Control Rod Drive Mechanism nozzles at other plants

2 9

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Davis-Besse plans to install FLÜS Online Leak Monitoring System
  • Ability to detect and locate leakage with significantly higher sensitivity than other available systems
  • Leak detection system measures the moisture penetrating a sensor tube
  • Installed or being installed in 12 units in a variety of European countries and Canada
  • Operational history of 10 years

3 0

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Sensor Element Non-Sensitive Tubing

3 1

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002

  • Install sensor tube between the reactor vessel insulation and reactor vessel
  • Simple installation
  • Expected sensitivity of approximately 4E-3 to 2E-2 gpm
  • System sensitivity is dependent on the air tightness of reactor vessel insulation FLÜS SENSORS RV Insulation

3 2

Davis Davis--Besse Besse Nuclear Power Station Nuclear Power Station November 26, 2002 November 26, 2002 Gary Leidich Executive Vice President - FENOC

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