ML14016A169

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Presentation Regarding Use of High Density Polyethylene (Hdpe) Piping as Replacement for Underground Piping January 7, 2014 -Catawba Nuclear Station Hdpe Relief Request
ML14016A169
Person / Time
Site: Catawba  Duke Energy icon.png
Issue date: 01/07/2014
From: Lefler S
Duke Energy Corp
To:
Office of Nuclear Reactor Regulation
References
Download: ML14016A169 (23)
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Text

Catawba Nuclear Station HDPE Relief Request January 7, 2013 Steve Lefler - Principal Engineer Duke Energy

Catawba Nuclear Station HDPE Relief Request Summary of Catawba Relief Request

  • Relief request approved for third inspection interval.

Catawba Nuclear Station HDPE Relief Request

  • Catawba Relief 06-CN-003 for use of HDPE was authorized by NRC May 27, 2009 letter.

m Unit 2 HDPE piping placed in service 10/6/2010 m Unit 1 HDPE piping place in service 06/07/2011

Catawba Nuclear Station HDPE Relief Request BACKGROUND ON HDPE USE AT CATAWBA Operating Problems with Carbon Steel Piping

- Fouling and Occlusion ( During summer season, flow control valves fully open to the containment ventilation chillers with chiller condenser pressures near 150 psig trip set point

- Pin Hole leaks

- General Corrosion

- Selective Weld Attack

Catawba Nuclear Station HDPE Relief Request FOULING OF CARBON STEEL PIPE

Catawba Nuclear Station HDPE Relief Request FOULING OF CARBON STEEL PIPE

Catawba Nuclear Station HDPE Relief Request

  • Beginning around 1995, HDPE was used to replace 22,000 feet of non safety related cooling water piping.

- Excellent service experience

- HDPE 3408 Material used for non safety piping

- Less rigorous installation requirements

  • Noted performance improvements. After replacement with HDPE and two operating cycles, containment ventilation flow control valves 50 % open with chiller condenser pressure 25 psig under the trip set point.

Catawba Nuclear Station HDPE Relief Request Non Safety Related 32 inch HDPE piping

Catawba Nuclear Station HDPE Relief Request Timeline - Catawba HDPE Use

  • June 2005 - Meeting with NRC to discuss HDPE for ASME Class 3
  • October 2006 - Relief request submitted to the NRC
  • May 2009 - NRC issued Catawba safety evaluation

Catawba Nuclear Station HDPE Relief Request Supplemental Requirements to Code Case N-755

  • HDPE scratch depth allowance of 0.041 inches

° Reporting of ongoing industry HDPE test program results

  • Periodic tensile impact testing of field joints

" Provision for access to inside of pipe

" Remote visual inspection of fused joints from inside pipe

Catawba Nuclear Station HDPE Relief Request 90.041 inch allowable scratch depth based on testing for 4 inch, pipe (PE 3408) that qualified piping for resistance to slow crack growth with a gouge of 10% of the wall thickness.

  • For 12 inch SDR 11 pipe, 0.041 inches depth corresponds to 3.5% of the wall thickness.
  • Pipe with indications > 3.5% either cut out and replaced or indications removed by blending & verifying remaining wall thickness greater than design wall thickness.

Catawba Nuclear Station HDPE Relief Request Installation of 12 in NPS ASME Cl. 3 HDPE Piping

Catawba Nuclear Station HDPE Relief Request Ongoing Industry Testing Licensee will submit information obtained from industry HDPE testing program (such as tensile and fatigue tests, slow crack growth resistance tests on parent material and butt fusion joints, and SIF of various components)

If information supports operation of HDPE piping for the remainder of plant life, then this information will be submitted to the NRC staff for information only.

If results from testing program do not support use of HDPE piping for the remainder of plant life, information will be submitted to the NRC staff as part of a subsequent relief request for the next 10 year ISI Interval.

Catawba Nuclear Station HDPE Relief Request In Process Tensile Impact Testing

  • Impact tensile testing performed on fused joints.
  • Impact tensile test first fusion joint of each work shift for each fusing machine (daily joint).
  • oRequired to impact tensile test one random fusion joint chosen during a four work shift period.
  • Required to test at least 10 percent of field joints during production shift.
  • Fused joints involving fittings excluded from testing.

Catawba Nuclear Station HDPE Relief Request ASTM F 2634, Standard Test Method for Testing PE Butt Fusion Joints

Catawba Nuclear Station HDPE Relief Request Catawba NRC Safety Evaluation Requirements Periodic Tensile Impact Testing 1 107 66 16 189 43%

2 63 40 8 111 43%

1&2 170 106 24 300 43%

Catawba Nuclear Station HDPE Relief Request In Process Tensile Impact Testing

  • No failures of in process tensile impact tests provided high level of confidence in installed fused joints
  • At least 20% of the joints were tested each work shift compared to the minimum 10% requirement.
  • Random testing performed on 13% of the Unit 1 joints
  • Random testing performed on 11% of the Unit 2 joints

Catawba Nuclear Station HDPE Relief Request

  • Design shall provide access to inside of pipe

° Transitions from HDPE to steel were made in underground vaults

  • Remote visual examination was performed internally for fused joints during installation.

Catawba Nuclear Station HDPE Relief Request Access To Inside Piping Provided by Tee and Flange

Catawba Nuclear Station HDPE Relief Request Installation of 12 in NPS ASME Cl. 3 HDPE Piping

Catawba Nuclear Station HDPE Relief Request Installation of 12 in. NPS ASME Cl. 3 HDPE Piping

Catawba Nuclear Station HDPE Relief Reauest Hydrotesting of 12 in. NPS ASME Cl. 3 HDPE Piping

Catawba Nuclear Station HDPE Relief Request

  • Following HDPE installation, Unit 1 piping realized a 20-25% flow margin improvement for piping serving the diesel generators.
  • Following HDPE installation, Unit 2 improvement on the order of 15%. The Unit 2 improvement is less than Unit 1 improvement because of the smaller amount of piping on Unit 2.

mHDPE Piping used by Catawba has proven to be effective and cost efficient for solving fouling and corrosion problems.

Questions?

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