ML080250405

Licensee Handout for Meeting with Union Electric Company on the Callaway Plant Relief Request I3R-10 to Use Plastic Pipe in the Safety-Related Essential Service Water (ESW) System

ML080250405
Person / Time
Site:	Callaway
Issue date:	01/23/2008
From:	AmerenUE, Union Electric Co
To:	Donohew J NRC/NRR/ADRO/DORL/LPLIV
References
TAC MD6792
Download: ML080250405 (20)

Text

Buried ESW Piping Replacem ent At Callaway Plant Ameren UE"- Callaway Plant January 23, 2008 1 of 20

Agenda

° Introductions

• Overview of Essential Service Water (ESW) piping replacement at Callaway

- Background / Problem Summary

- Plan for Replacement

- Selection of HDPE

" Callaway's Relief Request (ULNRC05434)

• Scope of Work & Schedule

• One-Time Callaway ESW Completion Time Extension (ULNRC05445)-

• Comments, Questions & Discussion 2 of 20

Current Undergro..und ESW Piping Withheld 3 of 20

Background / Problem Summary

• The existing ESW system buried piping is made of carbon steel.

• Numerous corrective action documents have been written concerning the pinhole leaks, pitting and other localized degradation of the ESW system piping due to erosion, corrosion and microbiologically induced corrosion (MIC).

• The buried pipe degradation is internal versus external corrosion based upon visual inspection results, Close Interval Survey (IR drop) and Direct Current Voltage Gradient (DCVG) tests performed in early 2007.

• Inspections during RF1 5 have indicated that the "A" train 30" above ground pipe in the 1974' of the Control Building was significantly degraded, such that RF15 outage was extended, and it was replaced with carbon steel. The "B" train piping had numerous weld overlays performed for repairs. There were 4 pin hole leaks in the underground piping that were repaired during RF15. It was concluded the underground portions of the piping are in the same condition as those in the Control Building. Although none of the pinhole leaks or identified pits have been a structural issue, it is concluded the buried pipe needs to be replaced.

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Background / Problem Summary (cont'd)

• Callaway currently has an Operability Determination that is applicable to the ESW Piping with corrective action to replace the buried piping by RF16.

• Callaway has identified the ESW buried piping health as the 2 nd most important of the station health risks (behind the ESW small bore piping health risk).

• Resolving this health risk in a timely manner has been an issue with the NRC associated with Problem Identification & Resolution (Ref.

NCV 05000483/2007002-03 from 1st Quarter 2007). In addition it has been an item with INPO for-not resolving long standing equipment / station health issues which this risk has been. The replacement of this pipe is the proper solution and will close this long standing station health issue.

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Existing Buried Piping Pictures from Spring 2007 Outage 6 of 20

Overview of Replacement Plan

• The buried ESW system supply, return and strainer backwash piping, and sections of the above-ground ESW system piping in the ESW Pumphouse, the Control Building and the UHS Cooling Tower, that interface with the buried piping, will be replaced.

• Buried piping will be replaced with High Density Polyethylene (HDPE) piping using the guidance of ASME Code Case N-755.

• Above-ground -piping at the-interfaces will be replaced with type 316L. stainless steel, which is more resistant to MIC than carbon steel. This is consistent with previous above ground ESW piping replacements.

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Routing of Replacement Piping Overview Withheld 8 of 20

Basis for Sele'ction of HDPE

• The benefits and advantages of the use of the HDPE piping are given in the Plastics Pipe Institute (PPI)

Handbook as follows:

• Leak Free, Fully Restrained Joints

- HDPE heat fusion joining form'sleak-free joints as strong as, or stronger than the pipe itself.

• Corrosion & Chemical Resistance

- HDPE pipe will not rust, rot, pit, corrode, tuberculate or support biological growth.

Seismic Resistance

- HDPE pipe can safely accommodate i'epetitive pressure surges above the static pressure rating of the, pipe and is well suited for seismic loading due to its natural flexibility and fully restrained butt fusion joints.

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Basis for Selection of HDPE (cont'd)

" Construction Advantages

- HDPE pipe's combination of light weight, flexibility and leak-free, fully restrained joints permits unique and cost-effective installation methods that are not practical with alternate materials.

" Durability

- Properly designed, installed and"operated polyethylene piping systems can achieve a service life of 50-100 years and require little on-going maintenance. HDPE pipe is resistant to most ordinary chemicals and is not susceptible to galvanic corrosion or electrolysis.

" Hydraulically Efficient

- For water applications, HDPE pipe's Hazen Williams C factor is 150. Without corrosion, tuberculation, or biological growth HDPE pipe maintains its smooth interior-wall and the C factor does not decline over time.

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Callaway Relief Request

• ULNRC-05434 dated. August 30, 2007

" Requested approval date - May 31, 2008

" Callaway and Duke experience with HDPE on non-safety related systems

• Replacement piping being designed, procured, and installed using ASME Code Case N-755 with exceptions noted 11 of 20

Callaway Relief Request (cont'd)

Material (Section 2000) exceptions include:

- Latest revision of material standards referenced in Section 2000 used

- HDPE Cell Classification, of 445574C to be used

- 450 and 22.50 fittings may be used

- Provision for repair of damaged piping

" Cutting out and replacing bUdried piping, or

" Removing scratches and blending material - any piping section with damage greater than 10% of nominal wall thickness shall be cut out and replaced 12 of 20

Callaway Relief Request (cont'd)

Design (Section 3000) -exceptions include:

- Current code case limits piping to operation 140'F and 150 psig

- Callaway design pressures of various lines will be:

• 165 psig at 95 0 F

• 160 psig at 95 0 F e 45 psig at 1800 F

• ASME is in the process-of.revising Code Case N-755 R

- The proposed revision will allow operation at 180°F for short durations

- The proposed revision will allow long-term operation at 140°F and 200 psig 13 of 20

Callaway Relief Request (cont'd)

Update of changes/information since relief request provided:

- PPI letter provided showing acceptability of Dow DGDA-2492 BK 100 material (Cell classification 445574C) at -580 psi at.,,80°C (1760F) for 2 years

- Use of 175 0 F versus 180°F based on additional analysis ......

- Miner's Rule is used to account for operation under normal and post-accident operating conditions over the service life of the piping 14 of 20

Scope of Work ESW System In Service Work

- Excavations, relocations, and structural modifications

- All of the HDPE piping installat ion, examination and testing will be performed while the existing system piping is in service.

- New stainless steel piping spools will be prefabricated to the greatest extent possible with ESW system in service.

ESW System Out of Service Work

- Tie-ins to existing ESW system piping will be performed one train at a time with the plant online and the applicable ESW train out of service. A request has been submitted to allow a one time Tech Spec Completion Time extension from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days per train (Ref. ULNRC05445) 15 of 20

Implementation Schedule

• Excavation / Pipe Installation

- March 2008 - August,2008 Tie In to ESW system.

- September 2008

- Refueling Outage 16 scheduled to start October 11, 2008 16 of 20

One-Time Callaway ESW Completion Time Extension

• ULNRC-05445 dated October 31, 2007

• Requested approval .date June 1, 2008

• Implementation by December 31, 2008 17 of 20

One-Time Callaway ESW Completion Time Extension e Tier 1 -3 discussions on pages 11-1 6 of LAR Attachment 1

• Risk Metric Values ICCDP: 3.87E-06 per 14-day CT Delta-CDF: 7.74E-06 per-year ICLERP: 1.01 E-07 per 14-day CT Delta-LERF: 2.02E-07 per year

• Risk metric values less than those approved for Catawba (LA 228/223 dated 11-17-05,7 SE page 20) 18 of 20

One-Time Callaway ESW Completion Time Extension

" Normal (non-safety) Service Water Out-of-Service (OOS) times listed in Tier 2 discussion (page 13 of Attachment 1) are estimates only, not commitments

• Actual time that no service water (normal or ESW) will be available in the train being worked may vary from the LAR estimated values up to the entire 14-day CT

" Reported risk values assume no service water flow in the train being worked for the entire 14 days 19 of 20

Questions/Comments/Discussion???

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