Draft Response to BWRVIP-62 Rev. 1 RAI #15 · 2016-06-14 · Cycle 27 0.029 0.048 Cycle 28 0.100...

© 2016 Electric Power Research Institute, Inc. All rights reserved.

Joe GiannelliFinetech, Inc.

Raj PathaniaEPRI

BWRVIP Mitigation Committee MeetingSan Antonio, TX – June 15-16, 2016

Draft Response to BWRVIP-62 Rev. 1

RAI #15

2© 2016 Electric Power Research Institute, Inc. All rights reserved.

RAI #15 (Public Request #2)

The Paul Scherrer Institute (PSI) published plant OLNC data on March 27, 2014 at the Nuclear Energy and Safety Research Department Info Event 2014. The data showed that all the deposited platinum erodes within 35 weeks. Furthermore, the --- “released Platinum does not re-deposit on steel surfaces, but possibly becomes trapped on crud, fuel or in water clean-up system and is thus lost for protection--.” On what basis does the BWRVIP believe that an annual OLNC application is adequate?


RAI #15 (Public Request #2) - continued

1) The BWRVIP is requested to provide information on the durability of OLNC. The data suggests that platinum durability diminishes within one year, and, therefore, the staff requests BWRVIP provide an explanation on how can annual applications of platinum can effectively mitigate intergranular stress corrosion cracking.

2) The staff requests BWRVIP to confirm whether the ECP readings after 35 weeks of implementation of OLNC indicated any inadequate platinum in BWR units.

3) The staff requests that BWRVIP provide information on potential safety issues involving platinum deposits on fuel.


The BWRVIP is requested to provide information on the durability of OLNC. The data suggests that platinum durability diminishes within one year, and, therefore, the staff requests BWRVIP provide an explanation on how can annual applications of platinum can effectively mitigate intergranular stress corrosion cracking.

RAI #15, Part 1


Response: RAI #15, Part 1

Chart cited were preliminary unverified data presented at an internal event at PSI to show the capabilities of PSI's NobleChem™ research facilities. Chart indicates 300 g – 384 g of Pt injected. This is only 43%

to 55% of 700 g injected annually by this plant.Linear extrapolation is not correct; exponential decay

observed (NMCA).BWRVIP evaluation makes use of all of the available verified

Pt deposition monitoring results provided by PSI.PSI verified MMS and BDMS results from the same plant for

which data were cited are presented (Plant A, BWR-6, annual cycles, no prior NMCA) .


Response: RAI #15, Part 1 (Plant A)


Response: RAI #15, Part 1 (Plant A)

Exposure Period

As Received MMS Coupon

Loading (µg/cm2)

Pre-oxidized MMS Coupon

Loading (µg/cm2)

Cycle 27 0.029 0.048

Cycle 28 0.100 0.154

Sum Cycle 27+Cycle 28 0.129 0.202

Measured Cumulative Coupon Cycle 27+Cycle 28 0.174 0.220

• Cumulative results: Higher net mass Pt on coupons exposed for two consecutive cycles than the sum of Pt on coupons exposed for the same individual cycles.

• Pre-oxidized coupon loadings are higher than as-received.• Results indicate that Pt has a higher tendency to deposit and be retained on

stainless steel surfaces exposed to reactor coolant and ongoing OLNC applications for multiple cycles.



Cofrentes MMS coupon results presented previously are not included. – Discussed at the December 2015 Mitigation Meeting.– Uncertainties regarding deposit removal: Differences in results using

Laser Ablation + ICP-MS versus Acid Stripping + ICP-MS.– As of 6/6/2016, Cofrentes has not had additional coupons analyzed.


The staff requests BWRVIP to confirm whether the ECP readings after 35 weeks of implementation of OLNC indicated any inadequate platinum in BWR units.

RAI #15, Part 2



• Most plants monitor ECP in the MMS. No MMS ECP readings after 35 weeks of implementation of OLNC

have indicated inadequate Pt. MMS ECP after OLNC is maintained <-230 mV(SHE) at all plants. MMS ECP <-230 mV(SHE) indicates deposition in the MMS supply

line or ECP manifold and that the hydrogen:oxidant molar ratio in the reactor coolant is ≥2.

• In-process ECP measurements with OLNC are available from plants where ECP reference electrodes were installed in the RRS, BHDL or LPRM (lower plenum).


Response: RAI #15, Part 2: Plant A, RRS ECP

• BWR-6, annual fuel cycles, no prior NMCA (NWC).• Single OLNC application first cycle (Cycle 25), multiple applications in

subsequent cycles.• ECP decreased to -500 mV(SHE) immediately during the first OLNC,

gradually increasing to ~ -350 - 300 mV(SHE) by the end of the cycle. • ECP remained <-230 mV(SHE) from the initial OLNC that started on

11/24/2008 until the end of cycle, 8/8/2009: 269 days (38.2 weeks). • Results do not indicate inadequate platinum in 35 weeks after an OLNC

application.• ECP increased to approximately -180 mV(SHE) after RFO until next

OLNC application; one-time occurrence.• Throughout all subsequent operating periods, ECP has been <-230

mV(SHE) when HWC is available.


Response: RAI #15, Part 2 (Plant A, RRS ECP) Update


Response: RAI #15, Part 2: Plant C, RRS ECP

• BWR-2, 24-month fuel cycles, one NMCA (2000).• Initial OLNC in December 2006, approximately annual OLNC

reapplications.• Annual OLNC applications have maintained RRS ECP below -230

mV(SHE) over several operating cycles during operating periods with hydrogen injection.

• There were no indications of inadequate platinum between annual OLNC applications.


Response: RAI #15, Part 2 (Plant C, RRS ECP)

-600

-550

-500

-450

-400

-350

-300

-250

-200

-150

-100

10/10/06 2/22/08 7/6/09 11/18/10 4/1/12 8/14/13 12/27/14

ECP

(mV

SHE)

Avg Pt1 & Pt2 OLNC

Update


Response: RAI #15, Part 2: Plants D & E, Sister Units with BHDL ECP• BWR-4s, 24-month fuel cycles.• Plant D: NMCA in March 1999; NMCA reapplied in February 2006; initial

OLNC in July 2010 followed by annual reapplications.• Plant E: NMCA in March 2000; NMCA reapplied in February 2007; initial

OLNC in November 2011 followed by annual reapplications.• Annual OLNC applications have maintained RRS ECP below -230

mV(SHE) over several operating cycles during operating periods with hydrogen injection.

• There were no indications of inadequate platinum between annual OLNC applications.


Response: RAI #15, Part 2 (Plant D, BHDL ECP)

-600

-550

-500

-450

-400

-350

-300

-250

-200

1/3/03 1/2/05 1/2/07 1/1/09 1/1/11 12/31/12 12/31/14

ECP

mV(

SHE)

MMS ECP BHDL(Pt-3) NMCA OLNC

ECP values biased low by 30 mV(SHE) from NMCA to Apr-2013 due

BHDL Platinum Probe #3 used as primary mitigation monitoring parameter.

Forced Outages

Update


Response: RAI #15, Part 2 (Plant E, BHDL ECP)

-620-590-560-530-500-470-440-410-380-350-320-290-260-230

11/25/99 8/21/02 5/17/05 2/11/08 11/7/10 8/3/13

ECP

mV(

SHE)

BHDL(Pt1) ECP BHDL(Pt2) ECP New BHDL Probe NMCA OLNC

ECP values are 30 mV biased lower from Mar-2000 to Mar-2013 due to error in ECP calculation.

BHDL Platinum Probe #2 used as primary mitigation monitoring parameteruntil Feb-2015 RFO. A new Pt probe was installed and is now used as the primary mitigation monitoring parameter.

Pt1 and Pt2 ECP probes replaced

Update


Response: RAI #15, Part 2: Plant F, LPRM Lower Plenum ECP• BWR-4, 24-month fuel cycles, no prior NMCA.• Transition from HWC-M to OLNC 8/4/2014.• In response to the staff request to BWRVIP to confirm whether the ECP

readings after 35 weeks of implementation of OLNC indicated any inadequate platinum in BWR units:• Plant F ECP readings after 35 weeks (4/6/2015) was -374 mV(SHE),

most conservative reading. • On 7/23/2015, 357 days (51 weeks) after the first OLNC application,

the ECP reading was -379 mV(SHE).• Maximum ECP reading was -351 mV(SHE) during operation

following the first OLNC. • The second OLNC application started on 7/24/2015, and ECP was

lowered to approximately -490 mV(SHE) within the first day.• Results continue to be monitored to confirm the effectiveness of annual

OLNC applications.

Update


Response: RAI #15, Part 2 (Plant F, LPRM Lower Plenum ECP)Update


Response: RAI #15, Part 2 (Plant F, LPRM Lower Plenum ECP)Update

Mid

-Cyc

le O

utag

e

HWC-M

-550

-500

-450

-400

-350

-300

-250

5/1/2014 8/9/2014 11/17/2014 2/25/2015 6/5/2015 9/13/2015 12/22/2015

ECP

(mV(

SHE)

Pt-1 Pt-2 OLNC


Response: RAI #15, Part 2: Possible Additional ECP Results• Nine Mile Point 2 RRS ECP (BWR-5).• Brunswick 2 LPRM Lower Plenum ECP (BWR-4).


The staff requests that BWRVIP provide information on potential safety issues involving platinum deposits on fuel.

RAI #15, Part 3



Potential safety issues involving platinum deposits on fuel have been evaluated by the BWRVIP.– Noble metal deposits do not affect either the temperature threshold or rate at

which zirconium/water reaction occurs.– Licensing basis peak cladding temperature is not affected.– No impact on fuel rod thermal-mechanical performance or reactor safety.

There have been no safety issues involving platinum deposits on fuel since the initial NMCA at Duane Arnold in October 1996 (almost 20 years) and the initial OLNC at KKM in June 2005 (11 years). No fuel failures have occurred due to NMCA or OLNC. Surveillance programs have shown no evidence increased Zircaloy

hydride formation due to the presence of platinum or rhodium in fuel crud deposits. The amount of Pt injected is limited based on potential effects on fuel.

– Current OLNC guidance: No more than 10 µg/cm2 (based on fuel surface area) injected approximately annually.

– Continue to evaluate fuel surveillance results.


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Draft Response to BWRVIP-62 Rev. 1 RAI #15 · 2016-06-14 · Cycle 27 0.029 0.048 Cycle 28 0.100...

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