update on bwr water chemistry and mitigation · © 2018 electric power research institute, inc. all...

© 2018 Electric Power Research Institute, Inc. All rights reserved.

Update on BWR Water Chemistry and Mitigation

Drew OdellBWRVIP Integration Chair

NRC-Industry Technical Exchange Meeting

Rockville, MD

2© 2018 Electric Power Research Institute, Inc. All rights reserved.

Topics today…

Knowledge Transfer (aka Training)BWR Water Chemistry Guidelines (BWRVIP-190 Rev. 1)

Status and Future PlansBWR Chemistry PerformanceBWRVIP-62 Revision


Knowledge Transfer – via BWRVIP Mitigation Committee Bi-Annual BWRVIA User’s Group Meetings

– Knowledge transfer provided on radiolysis and ECP modeling to optimize hydrogen injection levels

– Hands-on training provided for code useMitigation Committee Knowledge Transfer

– BWR Water Chemistry Guidelines Training: Program Owner Overview and BWRVIP-94 Mandatory, Needed and Good Practice Guidance Environmentally Assisted Cracking Chemistry Control for Radiation Fields Chemistry Control and Fuel Considerations Chemistry Sampling PracticesWater Chemistry Transients and Cleanup

Considerations


History of the EPRI BWR Water Chemistry Guidelines…

Nine full revisions of Guidelines to date (blue boxes) Interim Guidance issued in 2010, 2011 and 2016 (light blue boxes) Implementation required 6-9 months after each document was issued Interim Guidance is as binding as Guidelines Review performed 2 years after guidance issuance, and annually thereafter until full revision

No official requirements as to the timing of document revisions

NP‐3589

‐SR‐LD

NP‐4946

‐SR (NWC plan

ts)

NP‐4947

‐SR (HWC plan

ts)

TR‐103515

BWRV

IP‐29

BWRV

IP‐79

BWRV

IP‐130

BWRV

IP‐190

Interim

Guida

nce (2010‐255)

Interim

Guida

nce (2011‐097)

BWRV

IP‐190

Rev. 1

Interim

Guida

nce (2016‐123)

1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020


BWR Guidelines – 2016 Interim Guidance Interim Guidance issued 2 Nov 2016

(BWRVIP Letter 2016-123)– 67 page document, 3 chapters, 3 appendicesGuidance included the following:

– Reduction in Action Level 1 RxW chloride from ≥5 ppb to ≥3 ppb

– Revision to Mitigation Performance Indicators (MPI) for NMCA & OLNC plants Added Excess Dissolved RxW H2 of ≥20 ppb Molar Ratio revised to ≥4 (hydrogen:oxidant)

in RxW at upper downcomer region Additional guidance on use of ECP, MMS,

and hydrogen benchmark (ramp) tests Implementation schedule included


Overview of BWR Water Chemistry Guidelines ReviewDecember 2017 Water Chemistry Guidelines Review Meeting:

– Report: 2017 Review of the BWR Water Chemistry Guidelines: BWRVIP-190 Revision 1: Committee Meeting Minutes (3002012381)

– Issues collected prior to the meeting were reviewed.– An additional issues were collected from the Dec 2017 meeting.– Decision: Interim Guidance will be developed in 2018 focused on High

Priority, High Impact issues. – The next full revision of BWRVIP-190 will start later, most likely 2020.As of February 2018, all issues related to the Guidelines have

been reported, reviewed and categorized.


2018 Interim Guidance Schedule

March Webcast (materials posted on EPRI.com)May White Paper DraftsMay White Paper Comment/ResolutionJune Interim Guidance Meeting (Face-to-face)July Interim Guidance Drafted for EPRI reviewAugust BWRVIP Mitigation Committee Review

(Includes Chem/RM and Fuel groups) September BWRVIP Integration Committee ReviewOctober BWRVIP Executive Committee ReviewNovember Issue Interim Guidance+9 Months Interim Guidance Implementation


BWR Chemistry Performance Update


U.S. BWR Fleet Reactor Water Conductivity Trend

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

1980 1984 1988 1992 1996 2000 2004 2008 2012 2016

Con

duct

ivity

(µS/

cm)

Rx Conductivity EPRI Action Level 1 Theoretical Conductivity at 25 deg C


U.S. BWR Fleet - Reactor Water Chloride Trend

0.0

0.5

1.0

1.5

2.0

2.5

3.0

2000 2002 2004 2006 2008 2010 2012 2013 2014 2015 2016

Rea

ctor

Wat

er C

hlor

ide,

ppb

Range Average

Ranges in 2008 and 2014 impacted by condenser in-leakage at one unit


U.S. BWR Fleet - Reactor Water Sulfate Trend

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Aver

age

Rea

ctor

Wat

er S

ulfa

te (p

pb)

DB F+DB FD All BWRs

Water Treatment System Types:DB = deep bed demineralizer onlyF + DB = prefilters + deep bed demineralizersFD = filter demineralizer only


U.S. BWR Fleet - Feedwater Iron Trend

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

Aver

age

Tota

l Fee

dwat

er F

e (p

pb)

Deep Bed Filter + Deep Bed Filter Demineralizer All


U.S. BWR - HWC Availability Trends (All Regimes)

75

80

85

90

95

100

2000(12)

2001(12)

2002(14)

2003(15)

2004(12)

2005(16)

2006(17)

2007(20)

2008(18)

2009(20)

2010(18)

2011(18)

2012(18)

2013(18)

2014(15)

2015(14)

HW

C A

vaila

bilit

y (%

)

Year of Cycle Start (# of BWRs)Range Average

Average has been >90% since 2000, >95% since 2004 and >98% since 2013.


Core Shroud Crack Mitigation


BWR-4 Core Shroud Cracking 12 month fuel cycles. First plant to report shroud cracking (1990); tie-rods installed.

– First indications of circumferential cracks in the HAZ of H4 weld.

Implementation of chemistry programs to mitigate IGSCC– 2000: NMCA+HWC– 2005: Initial On-Line NobleChem™ (OLNC) application First two applications were partial (approx. 18% and 50% of full annual

amount) 2007 – 2013: Single annual applications, ~199 g Pt at injected at 0.8 g/h

– 2013: Optimization of OLNC strategy - 2 applications each cycle with Pt injection rate ~0.3 g/h 1) 80 - 90 days after start-up of reactor, 100 g of Pt injected over 330 h 2) ~4 – 5 months later, 80 g of Pt injected over about 260 h


Summary: BWR-4 Core Shroud Crack Mitigation Circumferential cracks in the HAZ of H4 weld detected for the first

time in 1990 grew at a constant rate until 2005. After NMCA was performed in 2000, UT inspections of the core

shroud ID indicated that the desired reduction in crack growth rate had not been achieved. – Extensive evaluations concluded that the most likely cause for the observed

behavior was non-catalytic crack flanking produced by a nine-week period with no hydrogen following NMCA.

After OLNC was started in 2005, the crack growth rate decreased.– No new cracks have been found since 2005.

Pt injection strategy was changed in 2010 to 2 applications each cycle, with the same total amount, 0.3 g/h based on PSI NORA results. There has been no crack growth in the H4 weld between 2009

and 2015.


BWR4-G UT Results of Cracking in the H4 Weld

Leber, H. J., et al., “Mitigation and Assessment of SCC at the Core Shroud of Muehleberg Nuclear Power Plant” International Light Water Reactors Materials Reliability Conference and Exhibition, Chicago, IL, August 1-4 2016.


Core Shroud Reinspection Plans

Core shroud re-inspections have continued. Compilation and evaluation of new crack growth data is in

progress– Focus on results from inspections after the 2004 – 2008 timeframe.– Many additional plants have implemented OLNC since that time.This evaluation is to be completed in 2019.


BWRVIP-62 Revision 2 The U.S. BWR fleet has implemented Online NobleChem™ (OLNC).

– All operating units projected to use OLNC by end of 2020. Requirements in BWRVIP-62-A can be met under OLNC.

– Some enhancements are being considered based on knowledge advancements.

Interim Guidance for Mitigation has added Needed chemistry requirements has added more margin to ensure water chemistry control with OLNC.

Results of industry monitoring efforts demonstrate the effectiveness of OLNC in mitigating IGSCC – Pt mass deposition measurements– Pt particle size and particle density measurements– In-situ electrochemical corrosion potential (measurements)– Lowering of crack growth rates

BWRVIP-62 Revision 1 is being revised to incorporate the new data and will be replaced by BWRVIP-62 Revision 2


Together…Shaping the Future of Electricity

update on bwr water chemistry and mitigation · © 2018 electric power research institute, inc. all...

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