ML16242A178

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Presentation Slides from Public Meeting Regarding Calvert Cliffs GSI-191 Resolution Update
ML16242A178
Person / Time
Site: Calvert Cliffs  Constellation icon.png
Issue date: 09/01/2016
From: Kimberly Green
Exelon Nuclear Generation Corp
To: Richard Guzman
Plant Licensing Branch 1
Guzman R
References
Download: ML16242A178 (26)
v • d • e


Text

Calvert Cliffs GSI-191 Program Analysis of Longitudinal Welds, Debris Generation Centroid Approach, and Response to NRC Questions September 1, 2016

Agenda

  • Introductions
  • Objectives for Meeting
  • Analysis of Longitudinal Welds
  • Debris Generation Centroid Approach
  • Response to Requests for Information
  • Staff Questions & Concerns
  • Schedule for Future Periodic Meetings Calvert Cliffs Option 2b Refined Closure Plan 1

CCNPP Attendees

  • John Haydin - M&CU Engineering Manager
  • Andre Drake - Lead Responsible Engineer GSI-191
  • Ken Greene - Licensing Engineer
  • Craig Sellers - Project Manager GSI-191
  • Eric Federline - Project Support Calvert Cliffs Option 2b Refined Closure Plan 2

Analysis of Longitudinal Welds

  • Location of Longitudinal Welds in Containment
  • Locating and Orienting ZOIs on Longitudinal Welds
  • Analyzing ZOIs
  • Example Results - Longitudinal Break adjacent to a DEGB
  • Example Results - Max debris from main loop DEGBs and Longitudinal Welds Calvert Cliffs Option 2b Refined Closure Plan 3

Location of Longitudinal Welds

  • Primary Coolant Piping Calvert Cliffs Option 2b Refined Closure Plan 4

Locating ZOIs

  • Longitudinal Weld ZOI locations :

- Only model main loop longitudinal breaks in the SG Compartments

  • Ignoring the reactor cavity

- Ignore longitudinal welds shorter than the pipe ID

- If the longitudinal weld (measured along the axis of the pipe) is longer than the pipe ID, divide into equal segments, where the number of segments equals (length of the weld/pipe ID) rounded up to the nearest whole number (example below)

- Pipe ID = 42

- Length = 105

- #Segments = (105/42) = 2.5

- Round up to 3 segments

  • 2 ZOIs every 35 Calvert Cliffs Option 2b Refined Closure Plan 5

ZOIs on Longitudinal Welds (near side)

ZOIs on Longitudinal Welds (opposite side)

Analyzing ZOIs at Longitudinal Welds Full-size longitudinal ZOIs sized with a radius of (ZOI size) x (pipe ID) x 2 Partial break ZOIs sized normally: radius = (ZOI size) x (break size)

Longitudinal break ZOIs only allowed in the direction of the welds (see images)

Example Results Calvert Cliffs Option 2b Refined Closure Plan 6

ZOI on Longitudinal Weld (30-RC-5LU-A)

ZOI on Butt Weld (30-RC-12A-05)

Example Results - ZOIs Sized for Thermal Wrap Calvert Cliffs Option 2b Refined Closure Plan 7

Spherical ZOI on Butt Weld (30-RC-12A-05)

Hemispherical ZOI on Longitudinal Weld (30-RC-5LU-A)

Example Results Calvert Cliffs Option 2b Refined Closure Plan 8

Debris Generation Centroid Methodology

  • Insulation debris size distribution centroid methodology

- Generic ENERCON calculation (GSI191-CALC-001) provides methodology for calculating debris size distribution as a function of the average distance of insulation in the ZOI from the break (i.e., the centroid distance) based on the methodology recommended in NEI 04-07 Volume 2

- This methodology was discussed with NRC staff on Vogtle project August 11, 2016 Calvert Cliffs Option 2b Refined Closure Plan 9

RAI from December 1, 2016 Meeting

  • Provide head loss plots from strainer head loss tests

- Slides 11 through 17

- Slide 18

  • Provide justification that chemical precipitates will not form until after one CS pump is secured

- Slide 19

  • Welds with degradation mechanisms additional to design and construction flaws

- Slide 20

  • Discussion of non-piping LOCA initiators

- Slide 21

  • Justify basis for fiber fines as fibrous debris performance criterion for strainer

- Slide 22

  • Provide representative sequences leading to core damage in GSI-191 risk assessment

- Slide 23

  • Confirm materials of construction in RCS piping

- Slide 20 Calvert Cliffs Option 2b Refined Closure Plan 10

Head Loss Plot - Test 1, Full Debris Load with small pieces Calvert Cliffs Option 2b Refined Closure Plan 11 0

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0

1 2

3 4

5 6

0 10 20 30 40 50 Head Loss (ft-water)

Head Loss (in-water)

Test time (hours)

Chemical Head Loss Test 1 Non-Chemical Head Loss Chemical Effects Head Loss

Head Loss Plot - Test 2, Thin-Bed Test Calvert Cliffs Option 2b Refined Closure Plan 12 0

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0

1 2

3 4

5 6

0 5

10 15 20 25 30 Head Loss (ft-water)

Head Loss (in-water)

Test time (hours)

Chemical Head Loss Test 2 - Thin Bed Test Non-Chemical Head Loss Chemical Effects Head Loss

Head Loss Plot - Test 3, Fines Only Calvert Cliffs Option 2b Refined Closure Plan 13 0

0.5 1

1.5 2

2.5 3

3.5 4

0 4

8 12 16 20 24 28 32 36 40 44 48 8

12 16 20 24 28 32 Head Loss (ft-water)

Head Loss (in-water)

Test Time (hours)

Chemical Head Loss Test #3 Non-Chemical Head Loss Chemical Effects Head Loss

Head Loss Plot - Test 4, Fines Only Calvert Cliffs Option 2b Refined Closure Plan 14 0

0.125 0.25 0.375 0.5 0.625 0.75 0

1 2

3 4

5 6

7 8

9 0

10 20 30 40 50 60 70 Head Loss (ft-water)

Head Loss (in-water)

Test Time (hours)

Chemical Head Loss Test #4 Non-Chemical Head Loss Chemical Effects Head Loss

Head Loss Plot - Test 5, Fines Only Calvert Cliffs Option 2b Refined Closure Plan 15 0.00 0.25 0.50 0.75 1.00 1.25 1.50 0

2 4

6 8

10 12 14 16 18 0

10 20 30 40 50 60 Head Loss (ft-water)

Head Loss (in-water)

Test Time (hours)

Chemical Head Loss Test #5 Non-Chemical Head Loss Chemical Effects Head Loss

Head Loss Plot - Test 6, Rejected due to Improper Agitation Calvert Cliffs Option 2b Refined Closure Plan 16 0

0.5 1

1.5 2

2.5 3

3.5 4

0 4

8 12 16 20 24 28 32 36 40 44 48 5

10 15 20 25 30 35 40 45 Head Loss (ft-water)

Head Loss (in-water)

Test Time (hours)

Chemical Head Loss Test #6 Non-Chemical Head Loss Chemical Effects Head Loss

Head Loss Plot - Test 7 Calvert Cliffs Option 2b Refined Closure Plan 17 0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 2

4 6

8 10 12 5

10 15 20 25 30 35 40 Head Loss (ft-water)

Head Loss (in-water)

Test Time (hours)

Chemical Head Loss Test #7 Non-Chemical Head Loss Chemical Effects Head Loss

Aluminum Concentration

  • Largest Debris Load - Exceeds Strainer performance criteria

- Weld ISI 42-RC-11-W5 - DEGB at Hot Leg nozzle to SG11

  • 626 ft3 Thermal Wrap
  • 437 ft3 NUKON
  • 137 ft3 Generic Fiberglass
  • 31 ft3 Temp-Mat
  • 6.5 ft3 Mineral Wool
  • 0.2 ft3 Marinite
  • Critical Break Debris Load - Smallest debris load that exceeds strainer performance criteria

- Weld ISI 30-RC-12A DEGB at lower elbow RCP suction from SG12

  • 311 ft3 Thermal Wrap
  • 210 ft3 NUKON
  • 30 ft3 Generic Fiberglass
  • 11.5 ft3 Temp-Mat
  • 8.7 ft3 Mineral Wool
  • 0.15 ft3 Marinite
  • WCAP-15650 Al 1.66 ppm Calvert Cliffs Option 2b Refined Closure Plan 18

Chemical Precipitates & CS Pump Trip

  • Chemical Precipitants remain soluble until sump fluid cools to 140°F.
  • EOP-5 (LOCA) secures one CS pump when containment pressure is less than 2.8 psig.
  • GOTHIC analysis of maximum containment cooldown conditions in process.

Calvert Cliffs Option 2b Refined Closure Plan 19

RCS Materials and Weld with Degradation Mechanisms

  • Preliminary analysis shows critical break size is 30 cold leg break
  • RCS piping ASTM A-516 Grade 70 base metal with ASTM A-240 Type 304L mill cladding

- Butt and Longitudinal

  • Only welds with degradation mechanisms in addition to design & construction flaws are the Dissimilar Metal welds at RCPs subject which are also subject to PWSCC Calvert Cliffs Option 2b Refined Closure Plan 20

Non-Piping LOCA Initiators

  • Preliminary analysis shows critical break size is 30 cold leg break
  • Next largest potential opening in RCS is <21.25 SG manways

- Single-sided break too small to generate sufficient debris to threaten strainer performance

  • Valves, CEAs, and instrument lines even smaller.

Calvert Cliffs Option 2b Refined Closure Plan 21

Exclusion of Small Pieces of Debris

  • Test #1 included fines and small pieces of fibrous debris
  • Debris bed head loss was very low - 1.8 inches of water

- After addition if chemical precipitates

  • Remaining tests used only fine fibers. Small pieces were omitted.
  • All tests omitted RMI debris to avoid mixed bed with increased porosity.

Calvert Cliffs Option 2b Refined Closure Plan 22

Top Sequences Leading to GSI-191 Related Core Damage

  • Preliminary analysis shows only Very Large LOCA leads to GSI-191 related core damage.
  • Large Break LOCA Event Tree is shown below.
  • GSI-191 related failures result in loss of High-Pressure Recirculation (HPR)
  • Single sequence related to GSI-191 failures Calvert Cliffs Option 2b Refined Closure Plan 23

Questions/Concerns

  • Jointly Review Issues, Questions, and Concerns for Future Communication Calvert Cliffs Option 2b Refined Closure Plan 24

Next Steps

  • Finalize Update of Calculations
  • Present Formal Risk-Informed GSI-191 Analysis and Results
  • Desire Next Meeting - 4Q 2016 Calvert Cliffs Option 2b Refined Closure Plan 25
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