Text

Summary of Teleconference with Calvert Cliffs Nuclear Power Plant, Units 1 and 2 to Discuss Proposed Risk-Informed Approach to the Resolution of Generic LTR 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Des
	ML13030A348
Person / Time
Site:	Calvert Cliffs
Issue date:	02/07/2013
From:	Nadiyah Morgan; Plant Licensing Branch 1
To:	;
	Morgan N NRR/DORL/LPL1-1 301-415-1016
References
	TAC MC4672, TAC MC4673
	Download: ML13030A348 (86)
	v • d • e

t.p.1'I REGUi UNITED STATES

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NUCLEAR REGULATORY COMMISSION t:!

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WASHINGTON, D.C. 20555-0001 0

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February 7, 2013

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~o LICENSEE:

Calvert Cliffs Nuclear Power Plant, LLC FACILITY:

Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2

SUBJECT:

SUMMARY

OF JANUARY 8, 2013, TELECONFERENCE WITH CALVERT CLIFFS NUCLEAR POWER PLANT, LLC, TO DISCUSS THE PROPOSED RISK-INFORMED APPROACH TO THE RESOLUTION OF GENERIC LETrER 2004-02, "POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED WATER REACTORS" (TAC NO. MC4672 AND MC4673)

On January 8,2013, a Category 1 public meeting was held via conference call between the U.S.

Nuclear Regulatory Commission (NRC) and representatives of Calvert Cliffs Nuclear Power Plant, LLC, the licensee, at NRC Headquarters, Rockville, Maryland. The purpose of the meeting was to discuss the licensee's proposed risk-informed approach to the resolution of Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors (PWRs)" for Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 (Calvert Cliffs). A list of meeting attendees is provided in Enclosure 1 to this meeting summary.

The licensee (1) presented an overview of Calvert Cliffs' risk-informed approach and forecasted schedule to the resolution of GL 2004-02; (2) discussed the licensee's risk-informed approach versus previous NRC accepted methodologies for deterministic calculations and compared its approach to how South Texas Project (STP) is proceeding forward; and (3) began discussing the Calvert Cliffs chemical effects head loss considerations.

Discussion of the Risk-Informed Approach:

The licensee's overall approach is to use a risk informed solution with deterministic evaluations.

If testing can show that they have no chemical effects, the licensee will proceed with a deterministic evaluation.

The licensee provided Enclosure 2, which shows how the evaluations will be made similarly to or different from the approved deterministic guidance and also compared to how STP is moving forward in each area. The NRC staff commented in the following areas:

1. The licensee is not considering pipes less than 2 inches in diameter, but is considering breaks less than 2 inches in larger piping. The NRC staff believes that for a risk informed approach should include the smaller piping. This item was left open for evaluation. It was stated that the STP method was to exclude piping smaller than 2 inches.

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2. The NRC staff stated that the Calvert Cliffs ZOI for Temp-Mat (170) was overly conservative.

3. Unsure of the STP method at the time, the NRC staff stated that the STP debris transport methods were not the same as those in currently approved guidance, and that STP had stated that debris would not be assumed to be uniformly distributed in the pool at the start of recirculation.

4. The NRC staff questioned the licensee as to how it was determined that assuming the latent debris as 100% particulate was conservative for all cases. Some of the range of break cases may have a small amount of fibrous debris such that latent would be a significant contributor.

5. The licensee clarified that the fines distribution following blowdown would be determined per approved guidance.

6. The licensee clarified that they are planning on doing module testing to validate head losses assumed in the evaluation. They will use vertical loop testing as a chemical detector and use module testing for head loss. Module tests will not include chemicals.

7. The NRC staff stated that they were not in agreement that tests from WCAP-17057 could be used to justify higher in-vessel debris loads without additional evaluation. The NRC staff stated that the limits set forth in the NRC staff's safety evaluation for WCAP-16793 were based on the full range of tests run during the WCAP development, issues with the test facilities had not been explained, and that not all tests are considered to result in limiting values for debris loading.

8. The licensee stated that most mineral wool is being removed from the plant during the next refueling outage for each unit.

Discussion of the Chemical Effects Head Loss Considerations:

The licensee provided Enclosure 3, which discusses the chemical effects head loss considerations for Calvert Cliffs. The NRC staff commented in the following areas:

1. The NRC staff noted the difficulty in providing feedback without understanding the licensee's entire methodology for evaluating chemical effects. As an example, the NRC staff stated that the conceptual test methodology described in Enclosure 3 seemed to be a more deterministic type approach than a risk informed approach. The licensee stated that their current approach is risk informed although they may ultimately pursue a deterministic evaluation depending on the outcome of testing. The NRC staff stated that any feedback provided is subject to change depending on the specific approach pursued by the licensee.

The NRC staff further noted that in many past cases the most meaningful feedback was provided by the NRC staff after the NRC staff understood how all pieces of a test program fit together and after the NRC staff had observed plant-specific testing.

- 3

2. The NRC staff asked if the chemical effects test program is considering both sump strainer and in-vessel chemical effects. The licensee stated that the program intends to evaluate chemical effects for both sump strainer and in-vessel applications.

3. The NRC staff stated that for a risk-based chemical effects evaluation, assessing the distribution of potential results becomes very important.

4. The NRC staff stated that the absence of visible precipitates during bench tests is not conclusive proof of the absence of precipitates. As an example, in a test with sodium tetra borate buffer (NUREG/CR-6913), Argonne National Laboratory experienced pressure drops that exceeded the capacity of the vertical test loop without visible signs of precipitate, even after the loop was cooled overnight.

5. The NRC staff and licensee discussed the importance of demonstrating that any debris bed designed to detect precipitates is indeed sensitive to chemical precipitates. The NRC staff stated that one way to demonstrate sensitivity is by incremental additions of small quantities of WCAP-16530 precipitate to determine how much precipitate was needed before a significant head loss increase was measured.

6. The NRC staff discussed their expectation that a complete set of plant materials be included in chemical tests since there may be materials interactions that impact the chemical source term that are not represented by the addition of a few dissolved species.

7. The NRC staff noted that the autoclave tests, intended to determine if the highest post LOCA temperatures create a significant fluid chemistry difference, need a defined criterion for significance and need to measure repeatability.

8. The licensee noted that Table 1, "CCNPP Parameters Affecting Chemical Effects" of should be considered draft and that further analysis is ongoing that will result in a change in some of these values.

9. In reference to Table 6 of Enclosure 3, the NRC staff noted that one of the key differences between the PWR Owners' Group (PWROG) bench tests (WCAP-16530-NP) evaluating dissolution of plant materials and confirmatory tests sponsored by NRC at Southwest Research Institute was the relative movement of fluid across the samples in the PWROG tests. The licensee stated that for bench tests they will consider some method to cause fluid motion over coupons or other debris types.

10. The NRC staff stated that the sample temperature profile for the final day of testing (Figure 17 of Enclosure 3) could provide an inaccurate indication of a precipitation temperature since kinetics could delay precipitation at a given temperature beyond the four hour temperature hold time.

Due to time limitations, the NRC staff was not able to provide feedback in some areas such as:

(1) concerning the application of head loss results from a vertical loop test to the sump strainer tests; and (2) resolution of phenomena identification and ranking table items. These discussions were deferred to a later date.

-4 A list of attendees is provided as Enclosure 1, but may not be all inclusive. The licensee's presentation is provided as Enclosure 2 and 3. Members of the public were in attendance.

Public Meeting Feedback forms were not received.

Please direct any inquiries to me at 301-415-1016, or Nadiyah.Morgan@nrc.gov.

adiyah S. Morgan, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318

Enclosure:

1. List of Attendees

2. Calvert Cliffs Risk-Informed GSI-191 Comparison Table

3. CCNPP-8157 -001, "Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant," Revision 0, November 16,2012 cc w/encl: Distribution via Listserv

LIST OF ATTENDEES JANUARY 8,2013, MEETING WITH CALVERT CLIFFS NUCLEAR POWER PLANT, LLC RISK-INFORMED APPROACH TO THE RESOLUTION OF GL 2004-02 CALVERT CLIFFS NUCLAR POWER PLANT, UNIT NOS. 1 AND 2

.. INAME----.~~*----~*

i Nadiyah Morgan I Paul Klein

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i Matt Yoder I Stephen Smith Services, Inc.

Cliffs lCalvert Cliffs Inc.

f-MPR Associates, Inc.

,-----------------------I Enercon Services, Inc.

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Cliffs

,Sargent &Lundy Ll(:~

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Quitoriano r"Diablo Canyon Power Plant r-*--~----------*

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Michael Griffin I Maryland Department of Environment

The following table compares the approach that is being implemented in the Calvert Cliffs risk-informed GSI-191 Resolution Project to the methodology that has been previously accepted by the NRC for deterministic calculations performed in accordance with NEl 04-07 as implemented by the associated SER (including acceptable refinements).

Topical Area NRC*Approved Deterministic Methods CCNPP Risk-Informed GSI*191 Resolution Project Comments Pipe Break Characterization Assume double-ended guillotine break Analyzed breaks from 11.2" to 31" consistent with NUREG-1829 including the double-ended guillotine break Consistent with NRC approved deterministic method, same as STP No difference, same as STP Break exclusion zones must be disregarded Break exclusion zones disregarded All piping locations in which breaks lead to recirculation should be considered.

All piping weld locations in which breaks lead to recirculation are considered.

Breaks at welds, same as STP No difference, same as STP NRC BTP MEB 3-1 is not appropriate for determining potential LOCA break locations MEB 3-1 not used for determining potential LOCA break locations Pipe breaks be postulated at locations that result in unique debris source terms and break locations that maximize debris transport.

All piping weld locations in which breaks lead to recirculation are considered.

No difference, same as STP Must postulate pipe breaks that affect locations containing high concentrations of problematic insulation All piping weld locations in which breaks lead to recirculation are considered.

No difference, same as STP No difference Piping less than 2 inches in diameter need not be considered Piping less than 2 inches in diameter not considered Page1of5

I Topical Area NRC-Approved Deterministic Comments Methods CCNPP Risk-Informed GSI*191 Resolution Project

-~~~~~

~~-~~

Use spherical or hemispherical ZOI No difference, same as STP Generation Debris Use spherical or hemispherical ZOI 17D ZOI also applied to Marinite, Marinite 17D ZOI for Nukon and Thermal-Wrap 17D ZOI for Nukon, Thermal-Wrap, and similar to STP

~~~~

11.7D ZOI for Temp-Mat with stainless CCNPP more conservative, STP has steel wire retainer 17D ZOI for Temp-Mat with stainless no Temp-Mat 4D ZOI for qualified coatings steel wire retainer 4D ZOI for qualified coatings No diffe~ence, same as STP Truncate ZOI at walls Truncate ZOI at walls No difference, same as STP 4-category size distribution for No difference, same as STP fiberglass debris including fines, small 4-category size distribution methodology (consistent with guidance pieces, large pieces, and intact blankets in SER appendices) 60% fines, 40% large pieces for Temp 60% fines, 40% large pieces for Temp-No difference. STP has no Temp-Mat debris Mat debris Mat 100% fines (10 11m) for qualified No difference, same as STP 100% fines (10 11m) for qualified coatings debris coatings debris 100% failure for all unqualified Partial failure of unqualified coatings Methodology consistent with STP coatings debris based on available data. Time-Pilot Project under NRC review.

dependent failure of unqualified coatings based on available data.

Unqualified coatings fail as 10 11m

-~~

Unqualified coatings fail in a size Similar methods previously particles if the strainer is fully covered distribution based on coating type and accepted by NRC for deterministic or as chips if a fiber bed would not be available data.

evaluations, same as STP formed.

Plant-specific walk downs required to CCNPP-specific walk downs used to No difference, same as STP determine latent debris quantity determine latent debris quantity

~~~~

Latent debris consists of BS% dirt/dust Latent debris consists of 100%

CCNPP more conservative and 15% fiber particulate Page 2 of 5

NRC-Approved Deterministic Topical Area CCNPP Risk-Informed GSI-191 Comments Methods Resolution Project Logic tree approach to analyzing Logic tree approach to analyzing Debris Transport No difference, same as STP transport phases: blowdown, transport phases: blowdown, washdown, pool fill, recirculation, and wash down, pool fill, recirculation, and erosion erosion All large pieces and a portion ofsmall Fines transport proportional to Similar methods previously pieces are captured when blowdown containment flow, grating and accepted by NRC for deterministic flow passes through grating.

evaluations, same as STP some small and large pieces.

miscellaneous obstructions capture

~~~~~

100% washdown of fines, limited credit Includes some new methodology for hold-up of small pieces, and 0%

100% washdown of fines. Credit for hold-up ofsome small piece debris on consistent with STP Pilot Project washdown of large pieces through concrete floors and grating. 0%

under NRC review.

grating washdown oflarge pieces through grating.

Pool fill transport to inactive cavities Pool fill transport to inactive cavities is CCNPP more conservative must be limited to 15% unless neglected.

sufficient justification can be made CFD refinements are appropriate for Recirculation transport based on Methodology for CFD modeling recirculation transport, but a blanket conservative CFD simulations and recirculation transport assumption that all debris is uniformly developed for the deterministic STP analysis previously accepted by distributed is not appropriate.

debris transport calculation. All debris NRC for deterministic evaluations, was not assumed to be uniformly same as STP distributed.

90% erosion should be used for non-Values are relatively close to the transporting pieces of unjacketed Probability distribution with a range of less than 10% erosion based on Alion empirically determined 10%

fiberglass in the recirculation pool erosion value recently accepted by unless additional testing is performed testing.

the NRC., same as STP to justify a lower fraction.

1 % erosion of small or large pieces of 1 % erosion of small or large pieces of No difference, same as STP fiberglass held up in upper fiberglass held up in upper containment.

containment.

Page 3 of5

Topical Area NRC-Approved Deterministic CCNPP Risk-Informed GSI-191 Comments Methods Resolution Project Debris Transport Minimal previous analysis on time-Time-dependent transport evaluated Several aspects ofthe time (continued) dependent transport for pool fill, washdown, recirculation, dependent transport methodology and erosion.

consistent with STP Pilot Project under:NIlC 1 CVICW Chemical Effects Corrosion and dissolution of metals and insulation in containment is a function of temperature, pH, and water volume.

Accepted model is WCAP-16530-NP.

CCNPP planning comprehensive CCNPP integrated chemical effects 100% of material in solution will integrated chemical effects head loss head loss test program will precipitate.

test program.

undergo review by the NRC.

Precipitates can be simulated using the surrogate recipe provided in WCAP 16530-NP.

Strainer Head Perform plant-specific head loss testing Performed plant-specific head loss No difference. simpler than STP Loss of the bounding scenario(s) with a testing ofthe bounding scenario(s) prototype strainer module.

with a prototype strainer module.

Address chemical effects head loss CCNPP planning comprehensive CCNPP integrated chemical effects using WCAP-16530-NP surrogates in integrated chemical effects head loss head loss test program will prototype strainer testing.

test program. So far to justify the undergo review by the NRC, conservatism.

similar to STP Minimum fiber quantity equivalent to Minimum fiber quantity equivalent to No difference, same as STP 1/16 inch debris bed on the strainers is 1/16 inch debris bed on the strainers is required to form a thin bed.

required to form a thin bed.

Bounding strainer head loss compared Time-dependent strainer head loss Similar methodology previously to bounding NPSH margin and compared to time-dependent NPSH accepted by NRC for deterministic bounding structural margin to margin and bounding structural margin evaluations, same as STP determine whether the pumps or to determine whether the pumps or strainer would fail.

strainer would fail.

Page 4 of5

Topical Area NRC-Approved Deterministic Methods CCNPP Risk-Informed GSI-191 Resolution Project Comments No difference, same as STP Air Intrusion Release of air bubbles at the strainer calculated based on the water temperature, submergence, strainer head loss, and flow rate.

Release of air bubbles at the strainer calculated based on the water temperature, submergence, strainer head loss, and flow rate.

NPSH margin adjusted based on the void fraction at the pump inlet NPSH margin adjusted based on the void fraction at the pump inlet No difference, same as STP Void fraction at pumps compared to a steady-state void fraction of 2% to determine whether the pumps would fail.

Void fraction at pumps compared to a steady-state void fraction of 2% to determine whether the pumps would fail.

No difference, same as STP Debris Bypass and Penetration Perform plant-specific fiber bypass testing of the bounding scenario(s) with a prototype strainer module.

Planning to perform plant-specific fiber bypass testing of the bounding scenario(s) with a prototype strainer module.

No difference, similar to STP Ex-Vessel Downstream Effects 100% penetration of transportable particulate and chemical precipitates.

Evaluate ex-vessel wear and clogging based on the methodology in WCAP 16406-P 100% penetration of transportable particulate and chemical precipitates.

Evaluate ex-vessel wear and clogging based on the methodology in WCAp*

16406-P No difference, same as STP No difference, same as STP In-Vessel Downstream Effects Compare fiber quantity on core to bounding 15 g/FA limit based on WCAP-16793-NP.

Use RELAPS simulations to show that cold leg SBLOCAs and all hot leg LOCAs would not result in core damage with full blockage at the base ofthe core. Use WCAP-170S7-P tests with conditions closer to the CCNPP to justify an appropriate fiber limit on the core.

Methodology consistent with STP Pilot Project under NRC review.

Evaluate reduced heat transfer due to deposition on fuel rods using LOCADM software.

No difference, same as STP Boron Precipitation No currently accepted methodology.

Methodology TBD Methodology consistent with STP Pilot Pt:oject under NRC review.

Page 5 of 5

CHEMICAL EFFECTS HEAD LOSS CONSIDERATIONS for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001, Revision 0 November 16, 2012 Prepared by:

Reviewed by:

Craig D. Sellers Gilbert L. Zigler

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 REVISION HISTORY Log Revision Description o

Initial Issue for NRC Staff Review

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Contents 1.0 Introduction................................................................................................................................................................ 1 2.0 Background.................................................................................................................................................................. 2 3.0 CCNPP Parameters................................................................................................................................................... 4 3.1 Discussion of Certain Key Parameters........................................................................................................ 5 3.1.1 Strainer Flow Rate...................................................................................................................................... 5 3.1.2 Aluminum in Containment..................................................................................................................... 5 4.0 Expected Impact from Chemical Effects at CCNPP...................................................................................... 6 4.1 WCAP-16530 Model Predictions................................................................................................................... 6 4.2 Alion Bench-top Chemistry Testing.............................................................................................................. 8 4.2.1 Visual Observations................................................................................................................................. 10 4.2.2 ICP Results................................................................................................................................................... 10 4.2.3 Test 10 Wet Chemistry Results........................................................................................................... 14 4.2.4 Comparison to WCAP-16530 Aluminum Dissolution Rate..................................................... 15 4.2.5 Bench-top Testing Summary............................................................................................................... 16 4.3 ICET Test #5......................................................................................................................................................... 16 4.4 NRC Aluminum Dissolution Testing........................................................................................................... 21 4.5 Chemical Effects Head Loss Test Experiments for CCNPP................................................................ 21 4.6 Summary................................................................................................................................................................ 25 5.0 Conceptual Test Methodology........................................................................................................................... 26 5.1 Specific Testing Issues...................................................................................................................................... 26 5.1.1 Test Temperature Conditions - Strainer Head Loss.................................................................. 26 5.1.2 Test Temperature Conditions - In Reactor Vessel..................................................................... 29 5.1.3 Detector Debris Bed................................................................................................................................ 29 5.1.4 Chemical Effects Head Loss.................................................................................................................. 29 6.0 Method for Applying Test Results.................................................................................................................... 30 6.1 Large Temperature Dependent Chemical Effects Head Loss........................................................... 30 6.2 Small Temperature Dependent Chemical Effects................................................................................. 30 6.3 No Chemical Effects........................................................................................................................................... 31 7.0 Conclusions................................................................................................................................................................ 31 8.0 References.................................................................................................................................................................. 32 Appendix A Resolution of Outstanding Chemical Effects PIRT Issues......................................... 37 pages ii

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 List of Fi~ures Figure 1: Temperature Profiles for WCAP-16530 Precipitate Prediction....................................................... 7 Figure 2: ICP Results of Aluminum Concentration verses Time........................................................................ 11 Figure 3: ICP Results of Silicon Concentration verses Time................................................................................ 11 Figure 4: ICP Results of Calcium Concentration verses Time............................................................................. 12 Figure 5: Trace Elemental Concentrations from Test 10...................................................................................... 13 Figure 6: Remaining Elemental Concentrations from Test 10............................................................................ 13 Figure 7: Concentration of Major Elements from Test 10.................................................................................... 14 Figure 8: Aluminum Corrosion Test with and without NUKON......................................................................... 15 Figure 9: ICET #5 Aluminum Concentration.............................................................................................................. 19 Figure 10: ICET #5 Calcium Concentration................................................................................................................ 19 Figure 11: I CET # 5 Silicon Concentation..................................................................................................................... 20 Figure 12: ICET #5 Day 30 Fiberglass Sample (high magnification)............................................................... 20 Figure 13: Raw Differential Pressure Data NaTB buffered Borated water solution.................................. 22 Figure 14: Pressure and velocity history in test ICET-5-1-B2_042606.......................................................... 23 Figure 15: Vertical Loop tests - 10 ppm Aluminum with and without 60 ppm Silicon........................... 24 Figure 16: Test Temperature - First 30 Days............................................................................................................ 28 Figure 17: Test Temperature - Final Day of Test..................................................................................................... 28 List ofTables Table 1: CCNPP Parameters Affecting Chemical Effects.......................................................................................... 4 Table 2: WCAP-16530 Elemental Release Prediction.............................................................................................. 7 Table 3: WCAP-16530 Precipitate Predictions........................................................................................................... 7 Table 4: Test 10 Materials & Material to Coolant Ratios......................................................................................... 9 Table 5: Comparison of Material Quantities Between CCNPP and ICET #5.................................................. 17 Table 6: NRC AI Dissolution verses WCAP-16530 AI Dissolution..................................................................... 21 Table 7: Detector Debris Bed Composition................................................................................................................. 29 iii

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012

1.0 INTRODUCTION

Calvert Cliffs Nuclear Power Plant (CCNPP) prototype strainer head loss testing [1] resulted in very low head loss with non-chemical debris but high head loss when chemical precipitates were introduced. The chemical precipitate used in the tests was Sodium Aluminum Silicate (NAS) produced in accordance with WCAP-16530 [2,3,4,5,6,7,8] (WCAP).

CCNPP is considering specific plant design changes to reduce the aluminum content in containment and improve net positive suction head (NPSH) margin to the emergency core cooling and containment spray pumps. These changes include:

1. Removing the "Power Scope" telescoping platform on the polar crane,

2. Replacing much ofthe mineral wool insulation with stainless steel reflective metal insulation,

3. Enlarging the drains from the refueling cavity to increase post-LOCA containment pool water level by reducing water hold up volumes,

4. Installing emergency sump suction temperature instrumentation to provide operational information related to NPSH to the emergency core cooling and containment spray pumps and

5. Removing much of the unnecessary fibrous insulation.

These changes to the plants will improve post-accident operator response, improve pump emergency core cooling and containment spray NPSH, and eliminate the majority of aluminum and alumina in containment except the aluminum contained in the refueling machine, the equipment hatch hoist, air-operated valve components, and instrumentation.

The cost of these modifications in terms of financial resources and dose are significant. Also uncertainties with in-vessel downstream effects, strainer bypass testing, and existing strainer head loss testing may result in additional significant costs. The cost of resolving generic safety issue (GSI) 191 at CCNPP using the existing deterministic approach is estimated to be as high as $30 million per unit.

Before fully committing to these costs, CCNPP has decided to pursue a risk-informed (RI) approach to resolving GSI-191 including additional chemical effects testing. The purpose of this white paper is to present a thorough discussion of chemical effects and the potential impact on emergency core cooling system (ECCS) suction strainer debris head loss and in-vessel long-term cooling.

Page 1 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 This paper:

1) documents the results of a literature review of testing that has been performed in support of GSI-191 chemical effects applicable to CCNPP;

2) determines Significant parameters relevant to chemical effects head loss at CCNPP;

3) develops recommendations for plant-specific experiments to realistically assess the impact of chemical effects on debris bed head loss at CCNPP; and

4) summarizes and provides an assessment of each ofthe 42 chemical effects PIRT issues.

The main objective ofthis effort is to realistically assess the impact of chemical effects on debris bed head loss at CCNPP in place ofthe current bounding methodology.

2.0 BACKGROUND

The current method used to address the chemical-effects issue at CCNPP is to follow the approach recommended in WCAP-16530-NP as approved by the NRC [9,10,11,12,13,14]. CCNPP performed a series of prototype strainer head loss tests using fiber and particulate debris mixtures based on conservative debris generation and transport analyses. The debris bed head loss in these tests was very small (less than 0.5 ft-water) and posed no concerns with respect to ECCS pump NPSH or air intrusion.

After stable head loss was achieved in the tests with conventional fiber and particulate debris, surrogate chemical precipitates were introduced into the test chamber. The surrogate chemical precipitate used in the tests was Sodium Aluminum Silicate (NAS) produced in accordance with WCAP-16530. The debris bed head loss from the precipitate was an order of magnitude higher (greater than 23 ft-water). This increased head loss posed significant ECCS pump net positive suction head (NPSH), debris bed deaeration, and strainer structural concerns.

The alarming head loss test results led CCNPP into many actions including structural modifications to the strainers, additional small-scale chemical effects testing, and additional large scale prototype strainer head loss testing with reduced debris loads and metered introduction of the surrogate chemical precipitates.

CCNPP performed a series of vertical loop, flat-plate debris bed screen tests to investigate the head loss impact ofWCAP surrogate precipitates [15]. Vertical loop head loss tests conducted using NAS precipitate produced in accordance with the WCAP resulted in large chemical effects head loss Page 2 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 similar to the prototype strainer tests. CCNPP then conducted vertical loop testing with potential in-situ formation of WCAP precipitates at various temperatures and durations, which resulted in no significant head loss. This indicates that the WCAP method for preparing chemical surrogates is a Significant source of conservatism. Therefore, CCNPP is currently considering options for addressing chemical effects more realistically.

Page 3 of 34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 3.0 CCNPP PARAMETERS CCNPP parameters applicable to chemical effects are presented in Table 1 below.

Table 1: CCNPP Parameters Affecting Chemical Effects Reference Post-LOCA Sump Fluid Volume 3,888,935 Ibm, 62,878.91 ft3 27 Maximum Mass & Volume Minimum Mass & Volume 4,608,356 Ibm, 76,550.76 ft3 27 Containment Pool Buffer & pH Boron Concentration [H3B03) 1936 ppm to 3105.5 ppm 27 Lithium

<4.1 ppm 28 Hydrochloric Acid (HCI) 6.4 ppm (Long Term) 27 Nitric Acid [HN03) 8.4 ppm (Long Term) 27 Sodium Tetra Borate (NaTB) 13750 Ibm (minimum) 27 Injection Phase pH

! 4.5 31 Recirculation Phase Maximum pH 27

=+ 7.75 Recirculation Phase Minimum pH 7.0 27 Fibrous Debris1 Transco Thermal Wrap (LDFG) 2112.0 Ibm to 1200.0 Ibm 29&32 NUKON (LDFG) 612 Ibm to 1080 Ibm 29&32 Generic Fiberglass (LDFG) 29&32 Temp-Mat 0.0 Ibm to 1237.5 Ibm 70.9 Ibm to 590 Ibm 29&32 i Mineral Wool 29&32 0.0 Ibm to 1440 Ibm

Lead Blanket Jacket 300 Ibm 29 Metallic Insulation Debris Transco SS RMI 4061bm (0.811 ft3) 32 Particulate Insulation Debris 5 Ibm (0.104 ft3)

Marinite Board (Calcium Silicate) 33 Dirt & Dust 150 Ibm 34 Coatings Debris Inorganic Zinc 1,148 Ibm (3.83 ft3) 35 Epoxy 210 Ibm (1.45 ft3) 35 127.4 Ibm (1.3 ft3) i Alkyd Enamel 35 Reactive Metals i Metallic Aluminum

! 90 ft2 29 Metallic Zinc (Galvanized Steel) 95,583 ft2 30 Copper TBD [See App A PIRT Item 3.81 Lead TBD rSee App A PIRT Item 3.71 On~anic Materials TBD [See App A PIRT Item 6.11 Lube Oil Concrete 66,300 ft2 Exposed Concrete 31 1 The ranges in fibrous debris quantities represent the existing debris loads specified for head loss testing from [32] and the plant configuration after potential insulation replacement modifications [29]

Page 4 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP*8157*001 Revision 0, November 16, 2012 3.1 Discussion ofCertain Key Parameters 3.1.1 Strainer Flow Rate CCNPP has a design ECCS recirculation flow rate of 5,000 gpm [16], an ECCS suction strainer with a total 6,060 ft2 of filtration surface area which when completely enveloped by the fibrous and particulate debris bed is reduced to a circumscribed surface area of 1,085 ft2 [17]. These result in a debris bed approach velocity of 0.0103 ft/s with the strainer completely enveloped with debris.

The large fiber bed on the CCNPP strainer produced by the limiting break and this low approach velocity combined to result in a thick debris bed with very low compaction, high porosity, and very low bed head loss. Subsequently when the WCAP surrogate precipitate provides complete coverage of the debris bed surface, the debris bed compresses dramatically and the head loss increases by approximately one order of magnitude.

3.1.2 Aluminum in Containment CCNPP uses Sodium Tetraborate (NaTB) as the containment pool buffer. Because CCNPP has no significant source of phosphate in containment it is expected that aluminum corrosion products and potential precipitates will be the most significant contributors to chemical effects at CCNPP.

3.1.2.1 Mineral Wool Insulation CCNPP has mineral wool insulation on portions of the safety injection lines, the shutdown cooling lines, and the regenerative heat exchanger. This mineral wool insulation is the largest contributor of aluminum per unit of mass ofany insulation in the CCNPP containment. Mineral wool has poor thermal performance issues and is a candidate for replacement should chemical effects testing and analyses indicate its removal is necessary.

3.1.2.2 Telescoping Platform CCNPP had an aluminum "Power Scope" telescoping platform installed on the top of the containment polar crane. This platform was the largest source ofmetallic aluminum in containment. The platform was rarely used and was removed during the CCNPP Unit 1 2012 refueling outage and is scheduled to be removed in the CCNPP Unit 22013 refueling outage.

3.1.2.3 Remaining Aluminum The aluminum remaining in containment at CCNPP consists of less than 90 ftz of metallic aluminum on the refueling machine, equipment hatch hoist, AOV components, and instrumentation. This small surface area ofaluminum cannot be mitigated in a practical manner.

Page 5 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 4.0 EXPECTED IMPACT FROM CHEMICAL EFFECTS AT CCNPP CCNPP used the WCAP-16530 methodology to determine the aluminum dissolution concentration and chemical precipitate debris source term. The WCAP-16530 methodology was used with a conservatively high pH. No refinements to this methodology, such as corrosion inhibition, were used. Empirical data are available that demonstrate that the WCAP-16530 methodology conservatively over-predicts aluminum dissolution and precipitation ofaluminum compounds.

CCNPP has a low concentration of dissolved aluminum in the containment pool as predicted by the WCAP-16530 methodology. The two most significant contributors to dissolved aluminum in CCNPP containment are the mineral wool insulation and the aluminum telescoping platform previously discussed. With these contributors, the predicted dissolved aluminum concentration is less than 10 ppm. With these contributors removed the predicted aluminum concentration is less than 2 ppm.

Additional chemistry testing has been performed in the industry that provides insight on the impact from chemical effects that can be expected at CCNPP. The WCAP-16530 model predictions and the additional chemistry testing are discussed below.

4.1 WCAP-16530 Model Predictions Alion Science and Technology (Alion) performed chemical precipitate prediction calculations [31]

for CCNPP using the WCAP-16530 model and methodology. No refinements were used in these calculations. A number of load cases were investigated. The load cases based on the bounds of parameters in Table 1 are discussed in this section.

The containment atmosphere and sump water temperature profiles used for the WCAP-16530 model predictions are shown in Figure 1 [31]. These are the temperature profiles developed for the CCNPP containment analysis which is intended to maximize temperatures. Less conservative temperature profiles were also used which resulted in reduced predictions of precipitate production. The sump pH was assumed to remain at the initial pH of 4.5 until the beginning of recirculation at 30 minutes into the accident at which time the pH was assumed to increase to the maximum pH of7.75.

The elemental releases predicted by the WCAP-16530 model are presented in Table 2 and the precipitate quantities predicted are presented in Table 3. The elemental concentrations and precipitate quantities are presented as ranges from minimum to maximum sump pool volume. As predicted by the model, the silicon concentration in the sump fluid is sufficiently high to favor the production of sodium aluminum silicate over aluminum oxy-hydroxides. Also, no calcium phosphate is predicted to be produced.

Page 60f34

300 280 Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 260 240 220

c. 200 E

(11 180 160 140 120 100 10000 100000 1000000 10000000 Time (s)

Sump Temperature, HLB

-Atmosphere Temperature, HlB Figure 1: Temperature Profiles for WCAP-16530 Precipitate Prediction Table 2: WCAP-16530 Elemental Release Prediction Temperature Transient After Temperature Transient Prior to RAS-low pH

'(...

RAS

High pH 10 100 1000 Element Existing Plant Insulation, etc. Replaced Calcium 38.4 to 32.9 ppm 31.1 to 26.9 ppm Silicon 72.5 to 56.6 ppm 60.6 to 49.4 ppm Aluminum 7.41 to 5.38 ppm 1.43 to 0.75 ppm Table 3: WCAP-16530 Precipitate Predictions Precipitate Existing Plant Insulation, etc. Replaced NaAIShOa 241 to 280 Ibm 33.8 to 54.1 Ibm AIOOH 0.0 Ibm 0.0 Ibm Ca3(P04)2 0.0 Ibm 0.0 Ibm Page 7 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 4.2 Alion Bench-Top Chemistry Testing Alion performed chemical effects bench testing [20,21,22] to determine the dissolution of aluminum, calcium, silicon, zinc and the formation of precipitates, as a function of time, in the presence of sodium tetraborate (NaTB) buffer solution. The purpose of these tests was to provide insight into the dissolution and corrosion of these materials in a combined, integrated post-LOCA environment as opposed to the single effects tests documented in WCAP-16530-NP. These tests were not performed for CCNPP.

The bench tests were performed in 350 mL boric acid solutions with Boron concentrations ranging between 1362 ppm and 2400 ppm and 0.7 ppm of Lithium (as LiOH); this mixture targeted a solution pH ranging from 7.5 - 9.0, with NaTB either present in the initial solution or incrementally added over the initial 30 minutes. The solution temperature was initially set at 200 OF +/-5 OF for the first 6 or 7 hours8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months followed by a decrease in temperature to 140 OF +/- 5 OF up through 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months or 30 days depending on the specific test.

The following tests were performed:

Test 1 AI, NaTB 24-hour test with all NaTB in the initial solution [20]

Test 2 AI, NaTB 30-day test with NaTB added incrementally over the first 30 minutes [20]

Test 3 Zn, NaTB 24-hour test with NaTB added incrementally over the first 30 minutes [20]

Test 4 NUKON, NaTB 30-day test with NaTB added incrementally over the first 30 minutes [20]

Test 5 Cal-Sil, NaTB 24-hour test with all NaTB in the initial solution [20]

Test 6 Cal-Sil, NaTB 30-day test with NaTB added incrementally over the first 30 minutes [20]

Test 7 Concrete, NaTB 24-hour test with NaTB added incrementally over the first 30 minutes

[20]

Test 8 AI, Zn, NUKON, Cal-Sil, Concrete, NaTB 30-day test with NaTB added incrementally over the first 30 minutes [20]

Test 9 AI, Zn, Cal-Sit Concrete, NaTB 30-day test with NaTB added incrementally over the first 30 minutes [20]

Test 10 Aluminum, Zinc, Temp Mat, Cal-Sil, NUKON, and Concrete Corrosion and Dissolution in NaTB, 30 day test with NaTB added incrementally over the first 30 minutes [21]

Test 11 Aluminum Dissolution and Corrosion in NaTB at High Temperatures [21]

Test 12 Cal-Sil Dissolution and Corrosion in NaTB at High Temperatures [21]

Test 13 Aluminum, Zinc, Temp-Mat, Cal-Sil, Alkyd Paint, Dirt/Dust, and Concrete Corrosion and Dissolution in NaTB and at High Temperatures [22]

Test 14 Aluminum, Zinc, Temp-Mat, Alkyd Paint, Dirt/Dust, and Concrete Corrosion and Dissolution in NaTB and at High Temperatures [22]

Page 8 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Material types and scaling of materials to fluid are important considerations when designing a chemical effects test and when comparing chemistry tests to plant-specific conditions. Scaling of materials such as insulation debris that is immersed in the sump fluid is performed on a volume basis such that the ratio of material volume to fluid volume is maintained. Scaling of material exposed to the sump fluid such as concrete and metal surfaces exposed to the sump fluid is performed in a surface area to volume basis such that ratio of the exposed surface area to volume of fluid is maintained.

Test 10 has the most materials common to CCNPP. The material to coolant ratios for CCNPP and Test 10 are compared in Table 4. The CCNPP ratios were calculated using the minimum sump pool volume in order to maximize the ratios. Also, the NUKON, Thermal Wrap, and Generic Fiberglass insulation at CCNPP were grouped as liE-Glass" as these are low-density fiberglass materials.

Table 4: Test 10 Materials & Material to Coolant Ratios Material to Coolant Ratio (per H20 ft3)

Material Test 10 CCNPP Aluminum [ft2) 0.36 0.0044 Zinc (ft2) 0.53 1.52 NUKON [ft3) rE-Glassl 0.027 0.0185 Temp Mat(ft3) 0.003 0.0006 Cal Sil (ft3) 0.0015 0.00001 Concrete (ft2) 0.047 1.06 Dirt/Dust (ft3) 0.00015 Alkyd Coatings rft3) 0.00002 Epoxy Coatings (ft3) 0.00002 Zinc Coatings (ft3) 0.00007 The material to coolant ratios for E-Glass and Temp Mat compare well and are conservatively higher in Test 10. Test 10 contained no Dirt/Dust, Alkyd, Epoxy, or Zinc coatings but the material to coolant ratios for these materials at CCNPP are very low and these materials are not expected to have a significant impact on chemical effects.

The ratio for zinc is 65% lower in Test 10 than at CCNPP. Test 3 investigated and compared the corrosion ofzinc in NaTB and Tri-Sodium Phosphate (TSP). The conclusion of this test was that the overall release rate for zinc ions was low but continued to increase in NaTB while it decreased in TSP and that the corrosion of zinc should be taken into account in a NaTB buffered pool. However, Integrated Chemical Effects Test (ICET) #5 [23] included galvanized steel in a NaTB buffered solution and concluded that zinc concentrations were present only in trace amounts, less than Page 9 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 1 ppm. Therefore, the contribution of zinc from galvanized steel is not expected to be a significant contributor to chemical effects at CCNPP.

The ratio for concrete is much lower in Test 10 than that at CCNPP. Test 7 investigated and compared the corrosion of concrete in NaTB and Tri-Sodium Phosphate (TSP). The results of this test show that concrete produced approximately 10 ppm of silicon, 8 ppm of calcium, 3 ppm of potassium, and insignificant concentrations of magnesium, aluminum, and zinc. The report further concludes that calcium leaching from concrete appears to be a direct source of available calcium potentially leading to the formation oftri-calcium phosphate. However, ICET #5 included concrete coupons in a NaTB buffered solution and no such precipitates were observed. Therefore, the contribution of calcium from concrete is not expected to be a significant contributor to chemical effects at CCNPP.

Bench-top test 10 was monitored for visual observations and test solutions, materials, and reaction products were examined by inductively coupled plasma atomic emission spectroscopy (ICP). The results of this bench-top test are discussed in the following sections.

4.2.1 Visual Observations The solutions for Test 10 remained relatively clear for the entire duration of the bench-top test. In addition, after each sample was taken it was observed that the solution remained clear as the solution cooled which suggests further that no precipitation formed during the course of the experiment. The metal test materials after removal from the test solution showed some dark discoloration on the coupon surfaces which is most likely from the oxidation due to water condensation and the lack of buffer availability at the metallic air/liquid interface.

4.2.2 ICP Results The ICP results for aluminum in solution from Test 10 are shown in Figure 2 along with the aluminum concentration predicted by the WCAP-16530 model for the same conditions. The aluminum concentration from Test 10 initially peaks at less than 4 ppm and then reduces to less than 2 ppm for the remainder ofthe test. The WCAP model predicts a steady increase to a concentration greater than 10 ppm.

Page 10 of34

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Figure 2: ICP Results ofAluminum Concentration verses Time The rcp results for silicon in solution from Test 10 are shown in Figure 3 along with the silicon concentration predicted by the WCAP-16530 model for the same conditions. The silicon concentration from Test 10 remains relatively constant at around 20 ppm. The WCAP model predicts a steady increase to a concentration greater than 100 ppm where it levels off.

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Figure 3: ICP Results of Silicon Concentration verses Time Page 11 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157 -001 Revision 0, November 16,2012 The ICP results for calcium in solution from Test 10 are shown in Figure 3 along with the calcium concentration predicted by the WCAp*16530 model for the same conditions. The calcium concentration from Test 10 increases at a relatively constant rate to around 75 ppm. The WCAP model predicts a much more rapid increase to a concentration greater than 120 ppm where it then remains constant.

o o

120 240 Test 10

-WCAP 360 480 600 720 Time (hr)

Figure 4: ICP Results of Calcium Concentration verses Time As can be seen in Figure 2, Figure 3, and Figure 4 the actual concentration of precipitants predicted by the WCAP-16530 model are significantly greater than the concentrations from Test 10. Test 10 also performed ICP for additional elements. Figure 5 shows the concentrations of cadmium, chromium, copper, iron, manganese, nickel, phosphorous, lead, and zinc which are present in only trace amounts.

Page 12 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 0.25

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 4.2.3 Test 10 Wet Chemistry Results The concentrations of the elements dissolved from materials in Test 10 are shown in Figure 7. The aluminum concentration levels are considered relatively low and coupled with the fact that no visual observations of precipitate formation were noted in the bench-top test, may lead to the conclusion that the amount ofany aluminum-bearing chemical precipitates being generated is probably small. The WCAP analysis of the bench-top conditions indicates that Sodium Aluminum Silicate would precipitate due to the stoichiometric excess of silicon over Al (>3 molar ratio). The additional amount of silicon released does not appear to be significant and is insufficient to be an aluminum corrosion inhibitor since a minimum of 50 ppm silicon is needed according to the refined WCAP model [24].

The potasium and magnesium concentrations are also considered low and these elements are not considered significant contributors to chemical effects. The ICP data, WCAP aluminum release rates and the lack of visual observation ofprecipitates suggests precipitate formation in solution is unlikely. However, the activity ofboth species may be high enough that some localized reaction may have occurred at material surfaces as would be implied in the case of silicate inhibition on Aluminum corrosion and hence manifested as deposits (i.e., the accumulation ofprecipitates on the insulation fibers and metallic coupons). In other words, the concentration of silicon may be lower in solution because it has formed a protective layer on the aluminum substrate or aluminum may not be abundant in solution because a portion ofit is being consumed to form precipitate on the fiber surface.

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Figure 7: Concentration ofMajor Elements from Test 10 Page 14 of 34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 4.2.4 Comparison to WCAP-16530 Aluminum Dissolution Rate Alion Tests 2 and 8 were bench-top dissolution tests of aluminum in a borated water solution buffered to a pH of 8.3 with NaTB, with and without NUKON (fiberglass insulation). The aluminum concentration results from Tests 2 and 8 are shown below and compared to WCAP prediction of aluminum release rate under the same conditions.

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1 Figure 8: Aluminum Corrosion Test with and without NUKON Alion Measured Aluminum Corrosion vs. WCAP-16530 Predicted Aluminum Corrosion The WCAP-16530 aluminum dissolution rate is shown to be consistently and significantly greater than the aluminum dissolution rate observed in these tests.

The WCAP-16530 prediction of aluminum released amount shown in Figure 8 was calculated using the WCAP spreadsheet and the bench-top test conditions. These conditions include 53.4 cm2 of aluminum in 350ml of a NaTB buffered solution at a pH of8.3 maintained at 200 of for 7 hours8.101852e-5 days 0.00194 hours 1.157407e-5 weeks 2.6635e-6 months followed by 140 OF for the remainder of the 30 day test. These test conditions do not simulate CCNPP sump conditions but they are reasonably similar.

Page 15 of 34

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 4.2.5 Bench-Top Testing Summary The Alion bench-top test program evaluated aluminum, zinc, Temp-Mat, Cal-SiI, NUKON, and concrete corrosion and dissolution in a NaTB environment with a pH of7.5-7.8. These material and chemistry conditions are very similar to those expected at CCNPP. From this testing the following conclusions have been drawn:

1) No visible precipitation was noted during testing.

2) Aluminum dissolution is minimal near neutral pH conditions.

3) Silicon and aluminum concentrations are low which may be related to silicate inhibition of aluminum corrosion due to silicon deposition on the aluminum substrate.

4) Aluminum concentrations are reducing over time which may also indicate that the aluminum in solution is being consumed to form precipitate on the fibers.

5) Aluminum concentrations are significantly less than those predicted by WCAP-16530.

From these results, it is concluded that one potentially important source ofchemical effects that may result from the presence of aluminum, zinc, Temp Mat, Cal-Sil, NUKON, and concrete in the specified NaTB environment may be related to the aluminum precipitation within the fiber bed and the impact of this change in bed morphology on debris head loss. It should be noted that these bench-top test results include insights gained from the ICP measurements of samples taken during testing. The measurements were performed by commercial laboratories and are therefore not considered safety-related output. As such, conclusions from these measurements provide insight into chemical phenomenology but the measurements themselves are not used for design purposes.

4.3 feET Test #5 In 2005, the USNRC and the Industry (through EPRI) developed a joint 30-day Integrated Chemical Effects Test (lCET) program. The ICET project simulated and monitored the chemical environment inside the containment sump containing the major structural and debris materials expected after a LOCA for 30 days.

As discussed earlier, material types and scaling of materials to fluid are important considerations when designing a chemical effects test and when comparing chemistry tests to plant-specific conditions. Scaling of materials such as insulation debris that is immersed in the sump fluid is performed on a volume basis such that the ratio of material volume to fluid volume is maintained.

Scaling of material exposed to the sump fluid such as concrete and metal surfaces exposed to the sump fluid is performed in a surface area to volume basis such that ratio of the exposed surface area to volume of fluid is maintained.

Page 16 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 The material to coolant ratios for CCNPP and ICET Test #5 are compared in Table 5. The CCNPP ratios were calculated using the minimum sump pool volume in order to maximize the ratios. Also, the NUKON, Thermal Wrap, and Generic Fiberglass insulation at CCNPP was grouped as "Fiberglass" as these are low-density fiberglass materials.

Table 5: Comparison ofMaterial Quantities Between CCNPP and ICET #5 Material to Coolant Ratio per H20 ft31 ICETTest #5 CCNPP Ratio ICET5/CCNPP

Material Zinc in Galvanized Steel rft2) 1.52 8.0 5.3 Metallic Aluminum (ft2) 0.0044 795 3.5 Copper (ft2) 6.0 Fiberglass Insulation (ft3) 0.0185 0.137 7.4 Temp-Mat Insulation (ft3) 0.0006 0.0 0.0 Marinite Fire Barrier (Cal-Sil) (ft3 0.00001 0.0 0.0 Concrete fft2) 1.06 0.045 0.04 Dirt/Dust (ft3) 0.00015 0.0 0.0 Alkyd Coatings (ft3) 0.00002 0.0 0.0 Epoxy Coatings (ft3) 0.00002 0.0 0.0 Zinc Coatings (ft3) 0.00007 65714 4.6 The material to coolant ratios for fiberglass and metallic zinc compare moderately well and are conservatively higher in fCET Test #5. The ratios for metallic aluminum and zinc coatings are excessively greater in Test #5 than at CCNPP.

Test #5 contained no Temp-Mat insulation, Marinite (Cal-Sil), Dirt/Dust, Alkyd, or Epoxy coatings but the material to coolant ratios for these materials at CCNPP are very low and these materials are not expected to have a significant impact on chemical effects.

The ratio for concrete is very much lower in Test #5 than at CCNPP. However, fCET #5 included concrete coupons in a NaTB buffered solution and no calcium or phosphate precipitates were observed. Therefore, the contribution of calcium and potassium from concrete is not expected to be a significant contributor to chemical effects at CCNPP.

From bench-top results presented in the previous section ofthis paper, the primary chemical interactions expected within the aluminum, zinc, Temp Mat, Cal-Sil, NUKON, and concrete in a NaTB buffered environment at a pH ranging from 7.5-7.8 are the relatively low dissolution of the silicon

<<25 ppm) and relatively low dissolution of the metals <<10ppm). The ratio of materials to fluid volume for the bench-top program (Test 10) compared favorably with CCNPP. The purpose of the Page 17 of34 I

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-81S7-001 Revision 0, November 16, 2012 following sections is to compare the results of the WCAP and bench-top tests to the industry data developed during ICET. The results ofICET Test #5 are summarized in Section 3 ofLA-UR-OS-9177

[23]. The test was conducted successfully for the entire 30-day period. The fluid kinematic viscosity and pH was steady for the entire test.

lCET Test #5 consisted of fiberglass in a NaTB buffered environment with a pH range of approximately 8.2 to 8.4. The comparison here is to investigate and possibly correlate the effects of pH on the materials. The amount of fiber that was present in the ICET test was also significantly greater than CCNPP and the maximum pH for CCNPP is lower than that of ICET Test #5. The chemical elements present were aluminum, calcium, silica, and zinc. Key observations from ICET#S were:

The submerged aluminum coupons lost approximately 3% of their weight, but there were very little weight changes on the other coupons.

The aluminum concentration in the test solution rose to SO ppm and then fluctuated between 33 ppm and 55 ppm for the remainder ofthe test.

The concentrations of zinc, copper, and magnesium remained below 1 ppm for the duration of the test. The iron concentration was essentially 0 ppm for the test duration.

The solution remained Newtonian throughout the test.

There was very little sediment on the tank bottom at the end of the test.

Examinations of fiberglass taken from the test apparatus revealed chemical byproducts and web-like deposits that spanned individual fibers. See Figure 12.

Flocculent deposits were also observed.

The amounts of these deposits did not appear to increase significantly over the duration of the test, and the web-like deposits were absent in the Day-30 samples.

Light, wispy precipitates were visible after the test solution sat at room temperature for several days.

The aluminum concentration in ICET Test #5 ( SO ppm) is significantly greater than that in the bench-top test <<4 ppm) and greater than that predicted by the WCAP-16S30 model (10.2 ppm). Comparing the ICET results with the WCAP results or bench top test results previously discussed is complicated by the fact that ICET Test #5 was conducted at higher pH (pH 8.2-8.4).

This may have a pronounced effect on the corrosion ofaluminum. It should also be noted that the ICET Test #5 experiment contained about 79Sx the amount of aluminum as CCNPP.

Page 18 of 34

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Figure 10: ICET #5 Calcium Concentration Page 19 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012

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Figure 11: ICET #5 Silicon Concentation Figure 12: ICET #5 Day 30 Fiberglass Sample (high magnification)

Page 20 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 4.4 NRC Aluminum Dissolution Testing The NRC performed dissolution tests of insulation materials to confirm the Westinghouse dissolution tests that formed the basis for the WCAP-16530 dissolution release rate model [25).

One conclusion ofthis testing was the NRC leachate concentrations were lower than the Westinghouse leachate concentrations for the same insulation product. The NRC results for aluminum dissolution from fibrous insulation materials were significantly lower that the Westinghouse results as shown in Table 6 below.

Table 6: NRC Al Dissolution verses WCAP-16530 Al Dissolution Source Material Test Temp Initial pH Final pH Al Conc.

NRC Fiberglass 265 0 F 12 12.0 4.3 ppm Westinghouse Fiberglass 265 0 F 12 12.0 8.6 ppm NRC Fiberglass 265 0 F 4.1 5.4 Not Detectible Westinghouse Fiberglass 265 0 F 4.1 6.2 1.7 ppm Westinghouse Nukon 265 0 F 4.1 5.9 1.0 ppm NRC Durablanket 265 0 F 12 12.0 15.6 ppm Westinghouse Durablanket 265 0 F 12 12.0 38.2 ppm As shown in Table 6, the aluminum dissolution concentrations used to form the basis for the WCAP 16530 methodology are more than twice NRC aluminum concentrations from confirmatory NRC testing. This indicates that the WCAP-16530 methodology may Significantly over predict aluminum dissolution from fibrous insulation materials.

4.5 Chemical Effects Head Loss Test Experiments for CCNPP Vertical loop chemical effect testing performed using a NaTB buffered boric acid solution with 10 ppm dissolved aluminum and 60 ppm dissolved silicon indicated that there is no significant increase in head loss due to chemical effect precipitation at temperatures down to 60 OF as shown in Figure 13 [15]. This indicates that aluminum precipitate formation at CCNPP, ifit occurs at all, may not detectably increase strainer head loss at temperatures above 60 OF, which is consistent with other testing performed with chemistry similar to CCNPP [26). During CCNPP vertical loop chemical effect testing, in addition to the lack of measured head loss impact, there was no visual indication ofaluminum oxy-hydroxide formation or precipitation.

Page 21 of34

08 Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision OJ November 16, 2012 o

NaTB: 0, 5, 10-ppm-AI

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4 120 100 80 60 40 T (F)

(I C 140 Figure 13: Raw Differential Pressure Data NaTB buffered Borated water solution

[60-ppm Si, 0, 5, & 10 ppm AI]

From analysis of the data shown above for the measured head loss as a function of test temperature, it can be determined that the temperature-dependent head loss variation can be attributed to the test loop fluid viscosity increase with decreasing temperature rather than chemical effects. Variations between results for the different aluminum concentration levels manifest uniformly at. all temperature levels and are merely indicative of minor variations in the test debris bed between tests.

The head loss test from NUREG/CR-6913 with chemistry most similar to CCNPP is test ICET-5-1-B2.

The results of this test are shown in Figure 14 below.

Page 22 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-S157-001 Revision 0, November 16, 2012 AI added Hel added at AlN03 added 50** (50 ppm) 1=8727 min (100 ppm total)

~ i~333m,"

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o 5000 10000 15000 Time (min)

Figure 14: Pressure and velocity history in test ICET-S-1-B2_042606 (Figure 66 from NUREGjCR-6913 [26])

The early aluminum concentration of 50 ppm is significantly greater than the maximum aluminum concentration for CCNPP and it produced no significant head loss increase during this test. As can be seen, the head loss did not increase significantly until the aluminum concentration reached 100 ppm. Recall that the maximum aluminum concentration at CCNPP is less than 10 ppm.

Alion also performed head loss test using NaTB buffered boric acid solution with 10 ppm dissolved aluminum with and without 60 ppm dissolved silicon. This testing involved the use ofsolid aluminum nitrate nonahydrate for the aluminum ion source and a laboratory-grade sodium silicate solution for the silicon which allows for in-situ formation ofAIOOH when silicon is absent and NAS with silicon present in sufficient concentration.

Results of head loss tests with 10 ppm aluminum with and without 60 ppm dissolved silicon are shown below.

Page 23 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 0.6 a... -

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Figure 15: Vertical Loop tests - 10 ppm Aluminum with and without 60 ppm Silicon These test results demonstrate the influence of silicon in reducing head loss. The reason for this head loss reduction is twofold:

1. At CCNPP there is an excess of silicon (Le., greater than a 3.12: 1 ratio) in all accident scenarios, which allows for the precipitation of NAS in lieu of AIOOH due to the reduced solubility and thermodynamic stability of NAS. Thermodynamic theory predicts the precipitation of NAS before that of AIOOH, which would prevent dissolved aluminum from forming AIOOH.

2. Argonne National Laboratory conducted bench-top tests that determined the particle sizes ofWCAP-16530 NAS and AIOOH surrogate precipitates based on the same concentration of aluminum [36]. The tests were not prototypic but instead comparative in nature, and used much higher concentrations of aluminum than are predicted for the CCNPP post-LOCA sump. The results of the bench-top testing indicate that for a given concentration of dissolved aluminum, the mean particle size of the AIOOH surrogate is approximately 25%

that of sodium aluminum silicate precipitate.

Applying these results to a pore-clogging model of head loss due to chemical effects, dissolved aluminum in the presence of excess silicon would have approximately 1j4th to 1j16th the effect on Page 24 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 head loss as dissolved aluminum without silicon. The exact relative magnitude of the effect on head loss is unclear but the significant difference in precipitate particle sizes alone suggests that AlOOH will have a significantly greater effect on head loss than NAS. Electrochemical interactions with the debris bed may increase the differentiation, but this is beyond the scope of the bench-top testing.

4.6 Summary CCNPP used the WCAP-16530 methodology to determine the aluminum dissolution concentration and chemical precipitate debris source term. The WCAP-16530 methodology was used with a conservatively high pH. No refinements to this methodology, such as corrosion inhibition, were used. Prototype strainer head loss testing resulted in very high head loss when the WCAP-16530 chemical precipitate surrogate was introduced.

Empirical data are available that demonstrate that the WCAP-16530 methodology conservatively over predicts aluminum dissolution and that the debris bed head loss from a more realistic consideration of chemical effects at CCNPP will be significantly less.

1. Alion bench-top chemistry testing at chemistry conditions and materials similar to those expected at CCNPP resulted in less aluminum dissolution and no visible precipitation.

2. ICET Test #5 was performed at chemistry conditions and materials similar to those expected at CCNPP. This test resulted in significant aluminum dissolution but the test was performed at a much higher pH and with 795x the amount of aluminum as CCNPP. This test produced little precipitation in the fluid but did result in chemical byproducts and web-like deposits that spanned individual fibers.

3. NRC aluminum dissolution testing concluded that the WCAP-16530 aluminum dissolution model may significantly over predict the dissolution of aluminum from fibrous materials.

4. Chemical effects head loss experiments performed for CCNPP resulted in no detectible debris bed head loss to temperatures down to 60 OF.

Page 25 of34

Chemical Effects Head Loss ConsiderationS' for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 5.0 CONCEPTUAL TEST METHODOLOGY The overall concept for the test is a long-term integrated chemical effects test with head loss measured throughout the test. A test duration of 30-days is considered long-term.

Materials used in the test will be representative of the materials submerged in the containment pool or exposed to containment spray. The material quantities will be scaled such that ratio of the test fluid volume to the volume of materials immersed in the pool fluid or the surface area of materials exposed to pool or spray fluid is consistent with the ratio of the volume of the post-LOCA pool to the submerged material volume or exposed material surface area at CCNPP. Initially, bounding quantities of materials will be used.

The test chemistry will begin with the initial post-LOCA pool chemistry expected at CCNPP. A scaled quantity ofNaTB buffer will be introduced to reflect the expected dissolution of buffer in the plant. Strong acids from the radiologic decomposition of electrical cables2 will be added periodically to the test at a rate similar to which these acids are expected to be produced at CCNPP.

No additional chemical or pH control will occur. The test chemistry will be allowed to evolve as it would in the post-LOCA environment at CCNPP. Water chemistry be periodically sampled and tested for chemical contents.

The test temperature conditions will replicate the CCNPP maximum post-LOCA temperature profile.

The last day of the test will be used to investigate low temperature chemical effects by reducing the temperature in stages until room temperature is achieved.

Head loss will be monitored throughout the test using a fiber and particulate debris bed formed on a flat perforated plate that has shown to be a good detector of head loss caused by chemical effects.

The debris bed will not be representative of the debris bed expected on the sump strainer at CCNPP but it will include similar fibrous material. The flow rate through the debris bed will yield a higher approach velocity than that expected at the CCNPP sump strainer. The flow rate used will be specified to increase the sensitivity of the debris bed to identifying head loss due to chemical effects.

5.1' Specific Testing Issues 5.1.1 Test Temperature Conditions - Strainer Head Loss The initial post-LOCA temperature of the containment pool at CCNPP is greater than 212 OF which requires testing in a pressure vessel to maintain liquid conditions. Visual observation of the debris 2 The radiologic decomposition of electrical cable insulation and resulting production of strong acids assumes significant core damage. The assumption of core damage is not consistent with successful ECCS performance.

Page 26 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 bed is critical when performing head loss testing across a debris bed. Also, introduction ofthe debris to form a debris bed in a pressurized vessel is difficult. The duration oftime the CCNPP sump temperature is above 190 OF is approximatelyB hours, or about 1 % ofthe 30 day test duration. A test will be performed for the duration when the CCNPP sump temperature is above 190 of using the actual CCNPP post-LOCA sump temperature profile. A second test using the same apparatus as the first one will be performed for the same duration as the first test except the temperature will be maintained at 190 of. The two tests are summarized as follows:

1. An autoclave containing the sump chemistry and scaled quantities of containment materials expected during the first 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months ofthe post-LOCA environment at CCNPP will be maintained at the CCNPP-specific sump temperature profile for 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . The test fluid will be examined for elemental concentrations, viscosity, turbidity, and the presence of any precipitates. The test materials will be examined for weight change, visual appearance, and the presence of any precipitates.

2. An autoclave containing the sump chemistry and scaled quantities of containment materials expected during the first 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months ofthe post-LOCA environment at CCNPP will be maintained at 190 OF for 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . Again, the test fluid will be examined for elemental concentrations, viscosity, turbidity, and the presence of any precipitates. The test materials will be examined for weight change, visual appearance, and the presence of any precipitates.

The results of these two autoclave tests will be compared and evaluated. Decisions on how to address any differences in the long-term test will be made after the results are evaluated. Options currently envisioned are:

1) If no significant differences are observed testing at the maximum temperature of 190 OF is acceptable

2) If significant differences are observed;

a.

Investigate whether a longer term test at 190 OF will replicate significant differences

b. Include the chemical differences in the initial phase of a test with a maximum temperature of 190 OF The test temperatures will then simulate the maximum sump temperature conditions within the limitations of the equipment; a maximum temperature of 190 OF is expected. To ensure that conservative reaction and precipitation kinetics are achieved and to meet the NRC staff guidance with regard to extrapolation of chemical effect test results, test temperatures will be maintained for equal or longer durations than those indicated by the plant maximum sump temperature profile.

Page 27 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157 -001 Revision 0, November 16,2012 The last day of the test will be used to investigate low temperature chemical effects by reducing the temperature in stages until room temperature is achieved.

Temperature Profile - First 30 Days 300

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200

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150 100 0,1 10 100 Tim.. (Hr)

- - Sump AOR Figure 16: Test Temperature - First 30 Days 150 140 130 1)0 Temperature Profile - Final Day 110

~

~ 100

~

90 80 10 60 50 no 1}2 124 726 118 730 732 734 736 738 TIm. (Hr)

--fl',t Figure 17: Test Temperature - Final Day ofTest Page 28 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16,2012 5.1.2 Test Temperature Conditions - In Reactor Vessel One of the PIRT issues is potential chemical effects caused by coolant passed through the reactor core where temperatures can be significantly higher than in the containment pool. This issue is discussed in Appendix A under Items 4.3 and 7.3.

5.1.3 Detector Debris Bed The debris bed formed on the flat plate screen is intended to provide a highly efficient filtering media capable of readily identifYing the head loss impact of potential precipitates on a qualitative basis. Since the head loss that is being monitored during the course of the test is meant to provide only a qualitative indication of chemical effects impact, the composition of the bed is designed more for filtering than serving as a prototypical debris bed for CCNPP. The goal in the debris bed formation is to establish a stable head loss prior to the addition of any chemical solutions.

Table 7: Detector Debris Bed Composition Substance Quantity (in grams)

NUKON 16 +/- 0.1 Silicon carbide 80 +/- 0.1 The debris loading for this particular configuration results in a particulate to fiber mass ratio of5:1.

5.1.4 Chemical Effects Head Loss A chemical effects head loss is defined as any change in head loss not attributable to expected non chemical effects reasons. Such reasons are changes in fluid viscosity and density with changes in fluid temperature.

Another reason is the gradual steady increase in debris bed head loss observed in most long term head loss tests. This is termed debris bed degradation. The cause of this gradual head loss increase is debris bed compaction and the subsequent decrease in porosity.

Multiple long term tests will be performed to address this issue. A Baseline test will be performed with the appropriate fluid chemistry but without the potentially reactive materials which will provide non-chemical effects long term head loss across the test temperature range. A subsequent test will be performed with the appropriate fluid chemistry and the potentially reactive materials which will provide total long term head loss across the test temperature range. Differences in these tests will be deemed chemical effects head loss.

Page 29 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 6.0 METHOD FOR APPLYING TEST RESULTS The method for applying the test results depends on the form of the results. Three possible forms of results are foreseen:

6.1 Large Temperature Dependent Chemical Effects Head Loss One form of result that is not expected but must be recognized as possible is a large chemical effects head loss on the detector debris bed at a specific temperature. Large chemical effects head loss is defined as a detector debris bed head loss increase of greater than 100% as compared to the head loss with no chemical effects. For example, if the head loss through the debris bed is initially 1 ft water but increases to 2 ft-water for a reason that cannot be explained by density and/or viscosity changes with temperature, this would be considered a large chemical effects head loss.

In this case, CCNPP will apply the WCAP-16530 chemical effects test head loss at all temperatures at or below the temperature at which the chemical effects head loss is observed to the CCNPP suction strainer. This WCAP-16530 head loss impact will be based on prototype strainer hydraulic testing using surrogate preCipitates generated in accordance with the WCAP-16530 model.

It is noted that the CCNPP prototypical strainer hydraulic testing produced strainer debris bed head loss values less than 10 mbar (-0.33 ft-water) prior to the introduction ofWCAP-16530 surrogate precipitates. The head loss increased to over 300 mbar (> 10 ft-water) which is an approximate 3000% increase. Therefore applying this total WCAP-16530 head loss when a >100% increase in detector debris bed head loss is conservative.

6.2 Small Temperature Dependent Chemical Effects One possible form of result that is more likely to be observed than the large impact is a small chemical effects head loss on the detector debris bed at a specific temperature. Small chemical effects head loss is defined as a detector debris bed head loss increase of less than or equal to 100%.

In this case, CCNPP will apply a ratio of the WCAP-16530 chemical effects test head loss at all temperatures at or below the temperature at which the chemical effects head loss is observed to the CCNPP suction strainer. The ratio will be the percentage increase in chemical effects head loss observed over the non-chemical effects head loss observed.

Chemical Effects Strainer Head Loss % head loss increase due to chemical effects observed in test x WCAP-16530 head loss.

Page 30 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157 -001 Revision 0, November 16,2012 For example, if the head loss through the debris bed in the test is initially 1 ft-water but increases to 1.5 ft-water for a reason that cannot be explained by density and/or viscosity changes with temperature, head loss increase due to chemical effects would be a 50% increase. Thus, if during the CCNPP prototypical strained hydraulic testing the stabilized strainer head loss prior to introduction ofWCAP-16530 precipitates was 2 ft-water and after introduction ofWCAP-16530 precipitates it stabilized at 6 ft-water, the strainer head loss attributable to chemical effects now becomes 2 ft-water + 0.5*(6 ft-water - 2 ft-water) =4 ft-water.

The CCNPP prototypical strainer hydraulic testing produced strainer debris bed head loss values less than 10 mbar (-0.33 ft-water) prior to the introduction ofWCAP-16530 surrogate precipitates.

The head loss increased to over 300 mbar (>10 ft-water) which is an approximate 3000% increase.

Therefore applying a percentage of this total WCAP-16530 head loss based on a >0% to 100%

increase in detector debris bed head loss is conservative. For example, a 20% increase in detector debris bed head loss translates into a 600% increase in debris bed head loss.

6.3 No Chemical Effects One form of test results is that no chemical effects head loss or in-vessel chemical reaction is observed. If this is the result, chemical effects can be ignored at CCNPP.

7.0 CONCLUSION

S This white paper summarizes the history of chemical effects impacts on suction strainer performance at CCNPP; identifies the parameters that are significant to chemical effects at CCNPP; describes chemical effects tests applicable to CCNPP, provided relevant CCNPP specific conditions; and describes a conceptual test program to more realistically assess the impact ofchemical effects at CCNPP.

Significant data are presented indicating that the WCAP-16530 model for chemical effects treatment is overly conservative for CCNPP. Implementation ofa comprehensive integrated chemical effects test program is expected to reduce the impact of chemical effects at CCNPP and avoid very costly plant modifications with little or no increase in safety margins.

Page 31 of 34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16,2012

8.0 REFERENCES

1. Design Calculation CA07051, Rev. 0000, Chemical Effect Head Loss Test Report

2. Westinghouse report WCAP-16530-NP, "Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids to Support GSI-191", February 2006, Revision O.

3. Westinghouse letter WOG-06-102, "Distribution of Errata to WCAp*16530-NP, 'Method for Evaluating Post-Accident Chemical Effects in Containment Sump Fluids' (PA-SEE-0275)", March 17,2006.

4. Westinghouse letter WOG-06-107, "PWR Owners Group Letter to NRC Regarding Error Corrections to WCAP-16530-NP (PA-SEE-0275)," March 21, 2006.

5. Westinghouse letter WOG-06-113, "Submittal ofWCAP-16530-NP, 'Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids to Support GSI-191' for Formal Review", March 27,2006.

6. Westinghouse letter OG-06-255, "Letter Releasing Revised Chemical Model Spreadsheet from WCAP-16530-NP," August 7,2006.

7. Westinghouse letter OG-06-273, "PWR Owners Group Method Description of Error Discovered August 16, 2006 in Revised Chemical Model Spreadsheet (PA-SEE-0275)," August 28,2006.

8. Westinghouse letter OG-06-378, "PWR Owners Group Letter Issuing Revised Chemical Model Spreadsheet (PA-SEE-0275)," November 15, 2006.

9. Office of Nuclear Reactor Regulation, "Request for Additional Information Re: Westinghouse Owners Group (WOG) Topical Report WCAP-16530-NP, 'Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids to Support GSI-191' (TAC No. MDll19)". October 4,2006.

10. Westinghouse letter OG-06-387, "Responses to the NRC Request for Additional Information (RAI) on WCAP-16530, 'Evaluation of Chemical Effects in Containment Sump FlUids to Support GSI-191"', November 21, 2006.

11. Office of Nuclear Regulatory Research, "Request for Additional Information Re: Pressurized Water Reactor Owners Group Topical Report (TR) WCAP-16530-NP, 'Evaluation of Post Accident Chemical Effects in Containment Sump Fluids to Support GSI -191' (TAC No.

MD1119)", March 23, 2007.

12. Westinghouse letter OG-07-129, "Responses to the NRC Second Set of Requests for Additional Information (RAJ's) on WCAP-16530, 'Evaluation ofChemical Effects in Containment Sump Fluids to Support GSI-191 111

, April 3, 2007.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012

13. Westinghouse letter OG-07 -408, "Responses to NC Requests for Clarification Regarding WCAP 16530, 'Evaluation of Chemical Effects in Containment Sump Fluids to Support GSI-191' (PA SEE-0275)", September 12, 2007.

14. Office of Nuclear Reactor Regulation, "Final Safety Evaluation by the Office of Nuclear Reactor Regulation Topical Report WCAP-16530-NP 'Evaluation of Post-Accident Chemical Effects in Containment Sump Fluids to Support GSI-191' Pressurized Water Reactor Owners Group Project No. 694", December 21, 2007.

15. Design Calculation CA07055, Rev. 0001 (ALION-REP-CCNPP-7311-001, CCNPP Chemical Effects Vertical Loop Head Loss Test Report, Revision 2).

16. CCNPP Design Specification SP-0908A, "Strainers for the Emergency Containment Sump Passive Type", Revision 3, April 24,2009.

17. CCI Calculation No.3 SA-096.080, Rev. 2

18. Office of Nuclear Reactor Regulation, "Evaluation of Chemical Effects Phenomena Identification and Ranking Table Results", March 2011.

19. NUREG-1918, "Phenomena Identification and Ranking Table Evaluation of Chemical Effects Associated with Generic Safety Issue 191", February 2009.

20. ALION-REP-LAB-2352-219, "Aluminum, Zinc, Insulation, and Concrete Corrosion and Dissolution in TSP and NaTB Test Report", Revision 1.

21. ALION-REP-LAB-2352-222, "Aluminum, Zinc, Temp Mat, Cal-Sil, Nukon, and Concrete Corrosion and Dissolution in NaTB Test Report", Revision O.

22. ALION-REP-LAB-2352-226, "Test Report of Aluminum, Zinc, Temp-Mat, Cal-Sil, Alkyd Paint, Dirt/Dust, and Concrete Corrosion and Dissolution in NaOH and NaTB and at High Temperatures", Revision O.

23. NUREG/CR-6914, Vol. 6, "Integrated Chemical Effects Test Project: Test #5 Data Report", LA UR-05-9177, Los Alamos National Laboratory, December 2006.

24. Westinghouse report WCAP-16785-NP, "Evaluation of Additional Inputs to the WCAP-16530 NP Chemical Mode!," Revision 0, May 2007.

25. U.S. NRC Center for Nuclear Waste Regulatory Analysis Technical Letter Report No. 1M 20.12130.01.001.320, "Supplementary Leaching Tests of Insulation and Concrete for GSI-191 Chemical Effects Program," November 2006.

26. NUREG/CR-6913, Chemical Effects Head-Loss Research in Support of Generic Safety Issue 191, Section 3.5.1 and Figure 66, December, 2006.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012

27. Design Calculation CA06963, "Mass of Sodium Tetraborate Decahydrate Buffer Required for Post LOCA Containment Building Sump pH Control," Revision 1.

28. CP-0204, "Specification and Surveillance Primary Systems," Revision 04502.

29. Letter from G. H. Gellrich (CCNPP) to Document Control Desk (NRC), dated December 30, 2010 "Supplemental Information Regarding Generic Letter 2004-02"

30. Design Calculation CA06774, "Containment Response to DBA's for CCNPP Unit 1 and 2,"

Revision 2.

31. ALION-CAL-CCNPP-7890-001, Revision 6, "Time-Dependent Chemical Precipitate Production Calculation for Calvert Cliffs Nuclear Power Plant."

32. Design Calculation CA06485, "Determination of Insulation Debris Loads on Emergency Sump Strainer," Revision 3, including change notices.

33. Design Calculation CA069405, "Computation of Aluminum and Marinite Board Debris Load Inputs for Containment Sump Strainer," Revision 1.

34. Design Calculation CA06886, "Containment Latent Debris Estimate for Sump Strainer Design Input," Revision O.

35. Design Calculation CA06938, "Determination Coating Debris Loads on Emergency Sump Strainer," Revision 1.

36. Argonne National Laboratory, Technical Letter Report on Evaluation of Chemical Effects; Studies on PreCipitates Used in Strainer Head Loss Testing," January 30, 2008.

Page 34 of34

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 APPENDIX A - RESOLUTION OF OUTSTANDING CHEMICAL EFFECTS PIRT ISSUES In March 2011, the Office of Nuclear Reactor Regulation issued a document titled "Evaluation of Chemical Effects Phenomena Identification and Ranking Table Results". This document summarized 42 potentially significant issues that required further evaluation based on an original list of over 100 chemical effects phenomena identified in NUREG-1918, "Phenomena Identification and Ranking Table Evaluation of Chemical Effects Associated with Generic Safety Issue 191". The NRC provided an evaluation of the remaining 42 issues in the March 2011 report, and dispositioned each item as either having a negligible impact on the results or having been adequately addressed in the current plant-specific analyses. In several cases, issues that were not directly addressed by the industry were considered acceptable based on conservatisms in the methodology used for the plant-specific analyses.

In an effort to understand the true impact that chemical effects could have on long-term core cooling in a plant-specific post-LOCA environment, several plants are conSidering the option of performing chemical effects testing that is more realistic than previous tests. Since the testing will attempt to reduce or eliminate overly-conservative methods that were used previously, it is also necessary to consider potentially significant issues that were not directly addressed previously.

This document summarizes and provides a brief assessment of each of the 42 chemical effects PIRT issues. The purpose of this assessment is to provide discussion points for the industry and the NRC to reach agreement on the conditions that must be explicitly modeled in realistic chemical effects tests.

During the NEI Chemical Effects Summit on January 26th and 27th, 2012, the initial revision ofthis document was presented and the resolution for each PIRT issue was discussed with the NRC and industry. Table 1 provides a list of each issue with the current NRC and industry positions based on the discussion during the chemical effects summit.

As shown in Table 1, the industry and NRC are in agreement on most of the PIRT issues that must be incorporated or can be excluded from realistic testing. Future discussions should focus on potential areas of disagreement, and the objective of these discussions should be two-fold:

Ensure that significant phenomena are properly addressed Avoid using limited resources to test insignificant phenomena Page A-l of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 P..

Table :

n ustl-y osltlOns on Ch

. I Eff\\ects PIRTl ssues 1 S ummaryofNRC andl d emlca

...,./' indicates a significant issue that must be addressed in realistic chemical effects testing X indicates an insignificant issue that can be neglected for chemical effects testing Item Phenomenon NRC Position

...,./'

Industry Position

-;7 RCS coolant chemistry conditions at break 1.2 pH variability J

../

1.3 Hydrogen sources within containment X

X 1.4 Containment spray C02 scavenging and C02/02 air exchange 1.5 ECCS injection of boron J

...,./'

2.1 Radiolytic environment J

J 2.2 Radiological effects: corrosion rate changes J

J 2.3 Hydrolysis X

X 2.4 Conversion of N2 to HN03 J

J 2.5 Additional debris bed chemical reactions J

X 3.1 Crud release J

X 3.2 Jet impingement J

J 3.3 Debris mix particle/fiber ratio J

J 3.4 Effects of dissolved silica from RCS and RWST J

J 3.5 Containment spray transport J

J

! 3.6 Initial debris dissolution J

J 3.7 Submerged source terms: lead (Pb) shielding J

...,./'

3.8 Submerged source terms: copper (Cu)

-J J 3.9 Concrete material aging X

X 3.10 Alloying effects J

J 3.11 Advanced metallic corrosion understanding

--:.7 J 3.12 Submerged source terms: biological growth in debris beds J

1\\

3.13 Reactor core: fuel deposition spalling J

...,./'

4.1 Polymerization X

X 4.2 Heat exchanger: solid species formation J

J.

4.3 Reactor core: precipitation J

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Page A-2 ofA-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012

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The following discussion provides additional details of the specific issues and how they should be addressed. The italicized text was copied directly from the NRC's March 2011 report describing the 42 issues.

Item 1.1: ReS coolant chemistry conditions at break The reactor coolant system (ReS) coolant chemistry varies over the fuel cycle. Boron concentrations vary from approximately 2,000 to 4,000 parts per million (ppm) at the beginning ofthe fuel cycle.

Therefore, the initial reactor water chemistry spewing out ofthe break and forming the containment pool will have variable boron concentration while the ratio oflithium to boron is approximately Page A-3 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157 -001 Revision 0, November 16, 2012 constant. The two-phase jet emanating from the break is initially at 315 degrees Celsius (C) (599 degrees Fahrenheit (F)) and then cools to 120 degrees C(248 degrees F). The main concern raised by the peer reviewers relates to how variations in the initial RC5 chemistry will affect the interaction with containment materials and whether these variations have been appropriately addressed. Variations may influence corrosion rates ofmetals, leaching ofspecies from nonmetallic materials, formation of chemical precipitates, and ultimately, plant-specific chemical effects.

The following root issues are contained in this item:

1. The break jet impacts different materials, and chemistry variations may have different effects.

2. Boron concentration in the RCS fluid varies over the fuel cycle.

3. Lithium concentration in the RCS fluid varies over the fuel cycle.

4. The temperature ofthe water exiting the break varies over the duration of the event.

The blowdown phase is brief (less than a minute for large break conditions), so chemical effects issues associated with impact by the break jet are negligible. After the blowdown phase ends, the water from the break would simply spill into the pool with minimal contact of containment materials.

Boron concentration is an important factor for chemical effects-partly due to potential chemical reactions, and partly due to its effect on pH. Therefore, a realistic boron concentration should be used to determine a realistic pH level, and an appropriate concentration should be added at the start of an integrated test. The RCS boron concentration at CCNPP ranges from approximately 2,700 ppm at the beginning of the fuel cycle to approximately 10 ppm at the end of the fuel cycle.

Lithium is not likely to be a major contributor to chemical effects since the concentration is generally low (ranging from negligible quantities to a few ppm). However, since it is relatively easy to include, a representative concentration of lithium should be added at the start of an integrated test.

Temperature is an important factor since it has a direct effect on corrosion rates and solubility limits. Therefore, a realistic analysis should take into consideration temperature variations over the duration of the event.

CCNPP Resolution Plan Long-term (30-day) tests will be run representing the bounding LOCA scenario that produces the largest quantity of debris. The quantities of materials in the test will be determined from the quantities of materials determined to be in the CCNPP containment for the bounding break, as Page A*4 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 determined by break modeling. The boron and lithium concentrations for each test will be selected by determining the concentrations in the RCS, RWST, and accumulators at CCNPP and calculating the concentration based on the contribution from each source for the LOCA scenario. The boron and lithium contributions from the RCS will be based on time-averaged concentrations. The impact ofhigher and lower concentrations of boron and lithium on the pH of the system will be evaluated using chemical equilibrium modeling. Ifthe modeling indicates that changes in solution chemistry cause deviations in pH that significantly affect corrosion or precipitation rates, bench-scale tests may be performed to investigate the rate of corrosion and extent of precipitation rates with higher or lower concentrations of boron and lithium. The temperature will be varied over the 30-day duration to match the temperature profile ofthe break scenario, with the exception that the effect of corrosion at temperatures higher than 190 OF will be addressed by autoclave testing as discussed in Section 5.1.1 ofthe main body ofthe paper.

Item 1.2: pH Variability The normal operating pH ofthe RCS is typically in the range of6.9-7.4. The pH adjusted to 25 degrees C(77 degrees F) changes during the course ofthe fuel cycle from acidic at the beginning ofthe cycle to closer to neutral by the end ofafuel cycle. There are implications similar to those discussed in Section 1.1 ofthis report with respect to how pH variations may affect the interactions between containment materials and the post-LOCA environment These variations may influence corrosion rates ofmetals, leaching ofspecies from nonmetallic materialsJormation ofchemical precipitates, and ultimately plant-specific chemical effects.

The following root issue is contained in this item:

1. pH level in the RCS fluid varies over the fuel cycle.

pH is an important factor since it has a direct effect on corrosion rates and solubility limits.

Therefore, a realistic analysis should take into consideration pH variations in the RCS fluid and the resulting impact on the overall pH in the pool.

CCNPP Resolution Plan The normal operating pH of the RCS at CCNPP is 7.1. The issue of pH variability over the fuel cycle is addressed by the selection of boron and lithium concentrations in Item 1.1.

Item 1.3: Hydrogen Sources within Containment Page A-5 ofA-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-815 7 -001 Revision 0, November 16, 2012 Dissolved hydrogen may playa significant role in the containment pool water chemistry. Hydrogen sources within the containment include the RCS inventory; the corrosion ofmetallic materials, including the reactor fuel cladding; and the Schikorr reaction. Containment pool reduction-oxidation (redox) potential is a function ofthe dissolved hydrogen reSUlting from these sources. Higher H2 concentrations may decrease the redox potential. However, containment conditions are expected to foster H2 evaporation, which could raise the redox potential. This issue could be important ifH2 concentrations have a significant effect on the redox potential in the post-LOCA containment water.

The redox potential determines which materials will corrode or dissolve within the pool. A higher redox potential (i.e., more oxidizing) promotes metallic corrosion. As the concentration ofdissolved constituents increases, so does the potential for solid species precipitation that could affect ECCS performance. The NRC or industry testing has not attempted to accurately simulate post-LOCA H2 concentrations. However, the Schikorr reaction, by itself, may be beneficial by converting compounds that could form gelatinous-type chemical species into the mineral magnetite.

The following root issue is contained in this item:

1. Dissolved hydrogen may increase corrosion or dissolution of materials in the containment pooL As discussed in the March 2011 review, Hz is considered inSignificant since there will be limited amounts of Hz in solution, and higher concentrations could actually reduce potential corrosion.

CCNPP Resolution Plan No action required.

Item 1.4: Containment spray C02 scavenging and C02/02 air exchange Air entrainment within the containment pool beginning soon after the LOCA will cause carbon dioxide (C02) absorption within the containment pool. This entrainment increases the amount ofC02" which could produce higher carbonate precipitate concentrations than would otherwise be present. These precipitates could also enhance nucleation and precipitation ofother chemical species. Consequently, Page A-6 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16,2012 the air j/iquid interactions within containment may increase the amount ofchemical precipitates and degrade ECCS performance more than ifthese interactions were not considered.

The following root issue is contained in this item:

1. Dissolved carbon dioxide may result in carbonate precipitates such as CaC03.

This is more ofan issue for plants that do not use TSP as a buffer since dissolved calcium can react with the TSP to form calcium phosphate precipitates. As discussed in the March 2011 review, tests that are open to the atmosphere would generally have a higher concentration of dissolved C02 than an air-tight containment. Therefore, although this is a potentially Significant issue that should be considered for air-tight tests, no additional analysis is required for tests that are not air-tight.

CCNPP Resolution Plan The CCNPP chemical effects testing will be performed in a facility that is not air tight to ensure that potential formation ofCaC03 will be appropriately represented in the test conditions.

Item 1.5: Emergency Core Cooling System Injection of Boron After a pipe break, RWST inventory with a boron concentration ofapproximately 2,800 ppm is injected into the RCS to cool the reactor core. This provides for a large boron source, which may affect chemical reaction products in the containment pool. Specifically, the boron source will serve as a pH buffer. This may influence corrosion rates ofmetals, leaching ofspecies from nonmetallics, and ultimately formation ofchemical precipitates.

The following root issue is contained in this item:

1. Boron concentration in the RWST will affect the pH in the pool.

Boron concentration is an important factor for chemical effects-partly due to potential chemical reactions, and partly due to its effect on pH. Therefore, a realistic boron concentration should be used to determine a realistic pH level, and an appropriate concentration should be added at the start of an integrated test. After a pipe break at CCNPP, RWST inventory with a boron concentration between 2,300 and 2,700 ppm is injected into the RCS to cool the reactor core.

Page A-7 ofA-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 CCNPP Resolution Plan The concentration of boron to be used in the testing is addressed in Item 1.1.

Item 2.1: RadioJytic Environment Radiolysis is the dissociation ofmolecular chemical bonds by a high energy radiation flux. The largest source ofthis radiation fluX is the gamma radioactive decay ofthe reactor fuel. When the ECCS fluid passes through the reactor core, it is subjected to this radiation flux. Radiolysis reactions may change the pH ofthe ECCS containment pool, the fluid's redox potential, or both. Hence, chemical species which differ from those evaluated mayform or the fluid may be more corrosive than that evaluated in all previous chemical effects testing.

The following root issues are contained in this item:

1. Radiolysis can affect pool pH through the creation of H20 2 and OH radicals.

2. Radiolysis can break down electrical cable insulation or dissolved nitrogen to form strong acids.

As discussed in the March 2011 report, the formation ofH20 2 and OH radicals is not considered to be a significant issue based on previous analyses. The formation of strong acids due to the breakdown of cable insulation or dissolved nitrogen may have a non-negligible impact on the long term pH, and therefore should be considered. As discussed in the March 2011 report, one licensee determined that acid formation would reduce the pH by 0.2.

CCNPP Resolution Plan A design calculation exists [27] that computes the amount of acid that could be formed long-term at CCNPP. The quantity of acid determined in this calculation will be included in the chemical effects tests.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157 -001 Revision 0, November 16. 2012 Item 2.2: Radiological Effects: Corrosion Rate Changes NRC

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Position Industry Position Radiolysis ofwater bearing the chloride ion {CI} can elevate the post-LOCA corrosion rate through formation ofhypochlorite {C/O} or hypochlorous acid (HOCI). The presence ofthese acids could increase the corrosion rate ofmetallic and nonmetallic species in containment, which in turn could alter the chemical byproducts formed. Hence, the chemical precipitates thatform could differ from those previously evaluated. These different precipitates could subsequently affect ECCS performance in a manner that has not been considered previously.

The following root issue is contained in this item:

1. Radiolysis ofwater with chloride ions can create strong acids.

Chloride ions may be in solution primarily due to the breakdown of electrical cable insulation, but also due to potential leaching from coatings. As discussed for Item 2.1, the formation ofstrong acids may have a non-negligible impact on long-term pH-and therefore will be considered.

CCNPP Resolution Plan The addition of acid to the tests to simulate radiolysis is addressed in Item 2.1.

Item 2.3: Hydrolysis Nickel oxide {NiOJ as well as other oxides, resulting from the corrosion ofstainless steel and Alloy 600 metals can become a catalyst for producing Hz from radiolysis ofwater. This process occurs more readily at higher water temperatures (i.e., hydrothermal environments). The hydrothermal hydrolysis ofva rio us organic/inorganic coating and insulation materials could partially depolymerize polymeric materials, producing materials ranging from small molecules to colloids. The colloids could subsequently aggregate into larger particles and gels. [fthis were to occur, the aggregated depolymerized materials may be more likely to transport to the sump strainer and affect pump performance or create chemical precipitates with different characteristics than those evaluated.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 The following root issue is contained in this item:

1. Hydrolysis may cause H2 formation.

As discussed in the March 2011 report, hydrolysis is a chemical reaction that causes water molecules to split into hydrogen and hydroxide ions. Hydrolysis is more significant at higher temperatures (generally above boiling). Since the containment pool temperature would only be above 200 Q F for a few hours, and the formation of H2 due to hydrolysis is a gradual process, this is an insignificant issue.

CCNPP Resolution Plan No action required.

Item 2.4: Conversion of Nz to HN03 One panelist was concerned about the effects ofnitric acid (HN03) formed in the containment pool due to radiolysis ofdissolved nitrogen (Nz). This panelist was mostly concerned that the HN03 concentration may overwhelm the buffering capacity and cause the containment pool pH to drop precipitously to a range within 1-3. Ifthe containment pool pH were this acidic, the redox potential becomes strongly oxidizing and corrosive and would lead to significant metallic corrosion and leaching ofinorganic ions from other materials (e.g., concrete). Most previous NRC and industry sponsored research has evaluated the chemical effects and their implications associated within the neutral-to-alkaline pH range (i.e., 7-10) that is expected within the buffered post-LOCA containment pool. Therefore, ifthe containment pool pH were highly acidic (i.e., 1-3), the chemical effects that would occur may differ Significantly from those previously evaluated. The implications ofthese effects on ECCS performance would also be largely unknown.

The following root issues are contained in this item:

1. Radiolysis of dissolved Nz may result in the formation of nitric acid.

2. Nitric acid may cause the pool pH to become strongly acidic.

As discussed in the March 2011 report, the formation of nitric acid due to radiolysis is expected to be relatively low due to the low solubility of N2 in water. The assumption that the pool could become strongly acidic did not take into account the presence ofthe buffers. Therefore, the pool is not expected to become strongly acidic. However, similar to the other issues regarding the Page A-I0 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16,2012 formation of strong acids, the effects on long-term pH due to the formation of nitric acid should be considered.

CCNPP Resolution Plan The addition of acid to the tests to simulate radiolysis is addressed in Item 2.1.

Item 2.5: Additional Debris Bed Chemical Reactions The concentration ofradionuclides, postulated to be hundreds ofCuries, available within the sump strainer fiber bed acts as a "resin bed" or chemical reactor potentially altering the local chemical conditions, such as pH. A number ofpossible radio/ytic reactions could occur which may directly alter the chemical byproducts formed. This effect may lead to the formation ofdifferent, or a larger quantity of, chemical products than those evaluated, which could have a different impact on head loss than that considered.

The following root issues are contained in this item:

1. Radionuclides trapped in the debris bed may change the local chemistry and cause precipitation.

2. Radionuclides trapped in the debris bed may cause the bed to break down.

As discussed in the March 2011 report, local changes in the chemistry (i.e. the formation ofHzOz due to radiolysis) will not have a significant effect since the constant flow through the debris bed will effectively flush it out. Also, the concern that the fiber bed may break down due to the radionuclides is not considered to be significant since materials similar to fiberglass insulation are routinely used as a filtration media for high activity particulate.

During the chemical effects summit, the NRC questioned whether other types of insulation or coatings debris besides fiberglass may break down in the debris bed due to the radionuclides.

The design of the ECCS is such that significant core damage is avoided. Therefore, provided the ECCS is successful, the concentration of radionuclides in the sump will be small. However, if key accident sequences in the PRA lead to core damage, the potential effects of large quantities of radionuclides in the sump may need to be considered.

Page A-l1 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 CCNPP Resolution Plan The non-fiberglass debris at CCNPP includes RMI, small quantities of mineral wool and marinite, and coatings debris. Coatings have been extensively tested in DBA conditions including high radiation. Radiation would not have any effect on the stainless steel RMI or the mineral wool debris. The marinite debris quantity at CCNPP is minor compared to the quantity of fiberglass debris. Therefore, even ifradiolysis did have an effect on marinite particulate, it would not significantly change the structure of the overall debris bed at CCNPP. Unqualified coatings may possibly break down due to the potential high radiation in a post-LOCA environment.

The CCNPP PRA model will be queried to determine the percentage of HELB initiating events that result in core damage. If the percentage of these events is significant, the chemical effects of radiation degradation of unqualified coatings will be investigated. If the percentage of these events is insignificant, no additional evaluation is required as the radiation levels during non-core damage events is not expected to be high.

Item 3.1: Crud Release A PIRT panelist postulated that iron and nickel corrosion oxides up to 125 microns thick may exist on the interior ofthe RCS piping,fuel, and components. These oxides could be released by the hydraulic shock ofthe LOCA event. After release, the reduced Fe and Ni ions can be dissolved in the RCS (aided by radiolysis) and, when combined with air, can form oxides ofhematite, maghemite, and magnetite.

The crud release can create a localized radiolytic environment on materials caught on the sump screens, which could affect subsequent chemical reactions. The crud particles would also add to the debris concentration within the containment pool.

The following root issues are contained in this item:

1. The crud may influence the localized radiolytic environment.

2. A significant quantity ofcrud could be released as another source of particulate debris.

As discussed in the March 2011 report, the radiolytic effects of crud are insignificant compared to other sources. The March 2011 report estimated that the total quantity of crud in the RCS could be on the order of 400 kg. This is a potentially significant source of particulate debris, but it is not likely that 100% of the crud would be released by the thermal and hydraulic shock ofa LOCA. The March 2011 report concluded based on transport considerations that this is not a significant issue.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 At the chemical effects summit, the NRC questioned whether the RCS crud could transport and have a significant impact on head loss.

STP performed an evaluation of crud release due to the thermal and hydraulic shock of a LOCA and determined the quantity of crud released would be on the order of 25 Ibs which is less than the assumed latent debris particulate load.

CCNPP Resolution Plan This item will not be addressed in the chemical effects tests. The crud is a source term for particulate debris and is not expected to affect the chemical environment.

Item 3.2: Jet Impingement The two-phase jet, and fine debris within the jet, will impact surfaces and could chip coatings, cause metallic erosion, or ablate materials like concrete. This phenomenon will govern the contributions of these materials in the early post-LOCA time period, before corrosion and leaching become important.

Jet impingement could also initiate pitting corrosion, which could accelerate the corrosion ofnormally passivated materials like stainless steel. Most ofthe discussion from the peer review panel describes the jet interaction with materials as the primary source for post-LOCA debris. Jet impingement could result in a potential chemical effects debris source term that is greater than currently anticipated.

The following root issues are contained in this item:

1. Debris can be generated by the jet blast.

2. Pitting due to jet impingement could accelerate corrosion.

The generation of debris and subsequent effects of that debris in terms of both debris bed head loss and chemical effects is an important issue that should be considered.

As discussed in the March 2011 report, jet impingement during blowdown has a very short duration, and any pitting that occurs would be localized and have a minimal effect on the overall quantity of corrosion products. Also, CCNPP-specific evaluations account for jet interactions with coatings and other containment materials, such as thermal insulation and fire barriers. The amount of material released from metallic erosion, concrete ablation, or metallic pitting induced by jet impingement will be inSignificant compared to the CCNPP design basis debris load used for strainer qualification.

Page A-13 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16,2012 CCNPP Resolution Plan The issue of jet impingement need not be addressed in the CCNPP chemical effects testing and analysis.

Item 3.3: Debris Mix Particulate/Fiber Ratio Breaks in different locations will create different debris characteristics with respect to the total mass ofdebris, debris constituents, and the ratio ofparticulates to fiber. Depending on the specific break location, significantly different types and quantities ofdebris (e.g., Cal-Sa and fiberglass insulations) can alter the type and quantity ofchemical effects. Ultimately, the debris bed characteristics determine the chemical product capture efficiency and the total pressure drop across the sump screen strainer.

The following root issues are contained in this item:

1. Different mixtures of debris can have a different impact on chemical effects.

2. Variations in the particulate/fiber ratio impact the chemical precipitate capture efficiency.

3. Variations in the particulate/fiber ratio impact the debris bed head loss.

In an integrated environment, the presence of some materials may inhibit the corrosion or dissolution of other materials. For example, silicon that is released into solution from the dissolution of fiberglass may inhibit the corrosion of aluminum. In some cases, therefore, scenarios with lower quantities of certain types of debris could potentially result in more severe chemical effects.

Fiber beds act as very effective filters and can capture small particles. As the particulate to fiber ratio increases, the debris bed is compacted and the filtration efficiency increases (along with the head loss). Therefore, the particulate to fiber ratio is a Significant parameter.

CCNPP Resolution Plan The mixture of debris to be used in the tests is addressed in Item 1.1. The long-term tests will use a special debris bed with a pre-defined ratio of particles to fibers that will be used as a head loss detection instrument to assess the relative impact of chemical effects under a standardized condition.

Page A-14 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-81S7-001 Revision 0, November 16,2012 Item 3.4: Effects of Dissolved Silica from Reactor Coolant System and Refueling Water Storage Tank Dissolved silica is present in the water storage systems and the RCS during normal operation. This silica can react with other chemical constituents (most prominently magnesium, calcium, and aluminum) thatform as a result ofmaterial dissolution or corrosion, or both, within the containment pool after the LOCA occurs. This reaction may result in a greater concentration ofthe chemical precipitates than would otherwise exist. The reaction may also alter the nature ofthe chemical precipitates by creating amorphous materials orgels or precipitates with retrograde solubility (i.e.,

they become more insoluble as temperature increases). The creation ofadditional chemical precipitates, amorphous materials, and retrograde soluble species could degrade ECCS performance by increasing head loss at the sump strainer or decreasing in the heat transfer rate from the reactor fuel ifsignificant quantities ofsilica-containing precipitates are formed.

The following root issue is contained in this item:

1. The dissolved silica initially in the water may precipitate with other materials later in the event.

Silicon is an important factor for chemical effects. In some cases, it may help inhibit corrosion of aluminum, and also can contribute to precipitate formation. Therefore, the initial concentration of dissolved silica in the RCS, RWST, and accumulators should be considered.

CCNPP Resolution Plan The quantity of silica present in the RCS, RWST, and accumulators at CCNPP will be evaluated along with the boron and lithium as described in Item 1.1, and the contribution of silica from each source during each test will be calculated and added at the beginning of the test as described for boron and lithium in Item 1.1 Page A-iS of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 3.5: Containment Spray Transport Following a LOCA, the containment spray will tend to wash latent debris, corrosion products, insulation materials, and coating debris into the containment pool. This changes the containment debris sources (types, amounts, compositions) and chemical species reaching the containment pool environment which could affect the sump strainer debris bed and the formation ofchemical precipitates.

The following root issues are contained in this item:

1. Corrosion products generated above the pool could be washed down into the pool.

2. Debris above the pool could be washed into the pool.

Both of these items are potentially significant and should be considered.

CCNPP Resolution Plan CCNPP prepared conservative debris generation and transport calculations that specifically addressed latent debris, corrosion products, insulation materials, and coating debris. The results of the conservative debris generation and transport calculations will be addressed in the CCNPP chemical effects testing and analysis. Also, the corrosion of materials exposed to containment spray above the pool will be accounted for in the chemical effects tests.

Item 3.6: Initial Debris Dissolution Typical debris generated by the LOCA (within the first 20 minutes) includes Cal-Sil insulation, cement dust, organic fiberglass binders, and protective coatings. Initial debris dissolution could indicate potential important contributors to the chemical containment pool environment. It is possible that the dissolved, ionic species could react and precipitate to form new, solid phases that were not originally in the containment pool.

Page A-16 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-81S7-001 Revision 0, November 16, 2012 The following root issue is contained in this item:

1. Dissolution of debris can form chemical precipitates.

This is the chemical effects issue and should be appropriately modeled in realistic chemical effects tests.

CCNPP Resolution Plan The relevant materials and debris determined to be present at CCNPP and contribute to chemical effects will be included in the test loop at the beginning of each test. Determination of the quantities of debris is addressed in Item 1.1.

Item 3.7: Submerged Source Terms: Lead Shielding Acetates present in the containment pool will corrode any submerged lead existing in containment, which could lead to formation oflead carbonate particulate or dissolved lead within the containment pool. Lead blanketing or lead wool is used to shield radiation hot spots during refueling outages and may remain in the containment building during the fuel cycle. In addition, several plants may still use small quantities oflead woolfor insulation.

Lead carbonate contributions would provide additional particulate loading within the containment pool that could contribute to head loss at the sump strainer screen. Dissolved lead could also lead to cracking ofsubmerged stainless steel structural components within containment. Neither the testing conducted to date nor do the licensee evaluations ofECCS performance consider these contributions.

These omissions are potentially non-conservative ifsignificant quantities oflead carbonate or dissolved lead are formed.

The following root issues are contained in this item:

1. Lead could dissolve and precipitate with other materials.

2. Dissolved lead may lead to cracking of submerged stainless steel components.

Generally, the quantity of lead exposed to the pool or sprays would be low. However, the dissolution of lead and subsequent precipitation is a potentially significant issue that should be considered.

Page A-17 ofA-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16,2012 As discussed in the March 2011 report, relatively low lead concentrations will not induce cracking in stainless steel components within the 30-day mission time.

CCNPP Resolution Plan An evaluation of the sources oflead in containment at CCNPP will be performed to determine whether there is a potential for significant lead quantities to be released into solution. If so, it may be necessary to include lead in the chemical effects tests. Determination of the quantity of lead debris is addressed in Item 1.1.

Item 3.8: Submerged Source Terms: Copper Copper present in containment can accelerate or inhibit corrosion ofother metals. One way in which Cu can alter the corrosion rate ofother materials is by forming a galvanic couple. Galvanic effects can accelerate corrosion ofless noble material while inhibiting corrosion ofmore noble materials.

Dissolved copper can also enhance the rate ofcorrosion ofother metals within an oxygenated environment. Different corrosion rates can impact the amount ofcorrosion products formed and therefore could have different effects on ECCS sump head loss.

The following root issues are contained in this item:

1. Galvanic couples can accelerate or inhibit corrosion of other metals.

2. Dissolved copper can enhance the corrosion rate of other metals by forming local galvaniC cells.

3. Copper can inhibit corrosion ofother metals by depositing and creating a passivation layer.

As discussed in the March 2011 report, the potential effect of galvanic couples in containment is insignificant Local galvanic cells may enhance corrosion ofaluminum, but this would only apply to the submerged aluminum. Also, as discussed in the March 2011 report, copper deposits were observed on aluminum samples in some of the ICET tests, which may have helped inhibit aluminum corrosion since the tests had negligible aluminum concentrations. Copper corrosion is expected to be relatively minor, but is a potentially significant issue that should be considered.

As discussed at the chemical effects summit, only the second root issue is important for chemical effects-potential enhancement of metal corrosion due to a local galvanic cell. The NRC also stated that the corrosion ofzinc (from galvanized steel or other sources), and subsequent formation of zinc precipitates is a potentially significant issue that should be evaluated.

Page A-18 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 CCNPP Resolution Plan An evaluation of the sources of copper and zinc in containment at CeN?? will be performed to determine whether there is a potential for significant quantities of these metals to be released into solution. If so, it may be necessary to include copper and/or zinc in the chemical effects tests. Determination of the quantity of copper and zinc is addressed in Item 1.1.

Item 3.9: Concrete Material Aging The PIRT panelists raised questions about the effect ofaging on the leaching process for nonmetallic materials such as concrete. Neither the exposed concrete faces nor concrete dust in the containment building is likely to be fresh. After 30years ofexposure to the atmosphere, a substantial fraction of both the exposed calcium silicate hydrate (C-S-HJ gel and the portlandite (Ca(OH)ZJ constituents ofthe concrete would have been carbonated. Carbonation or other aging processes ofconcrete could affect the leaching rates and dissolved species as compared to relatively fresh concrete samples used in the lCET experiments and other research programs.

The following root issue is contained in this item:

1. Aged concrete may release a larger quantity ofcalcium.

Concrete surfaces in containment are generally coated, which would prevent carbonation due to aging. However, this may be a significant issue for plants with large uncoated concrete surfaces; especially if the plant uses a TSP buffer. CCNPP has little uncoated concrete and does not use TSP as the buffer.

During the chemical effects summit, the NRC stated that the difference in dissolution between aged and fresh concrete is not significant and it is not necessary to use aged samples for chemical effects testing.

CCNPP Resolution Plan No action required.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-81S7-001 Revision 0, November 16,2012 Item 3.10: Alloying Effects NRC.

Position 'V Another issue raised by the PIRT is the effect ofdifferent alloys on the quantity ofcorrosion products.

Corrosion rate data exhibit wide variability depending on the specific corrosion conditions and the nature ofthe alloy being subject to corrosion. Alloying could affect dissolution and corrosion rates, thereby affecting the solid species precipitates that are formed.

The following root issue is contained in this item:

1. Differences in alloys may affect dissolution and corrosion rates.

As discussed in the March 2011 report, alloys would generally exhibit lower corrosion rates than pure metals. In realistic testing, it may be beneficial to use the actual alloys that exist in containment. Regardless, it is important to appropriately justify all surrogate materials (including metal coupons) that are used in chemical effects tests.

At the chemical effects summit, the NRC stated that there is not a large difference between corrosion rates for pure materials and alloys. However, it is appropriate to use materials that are representative of what is in containment.

CCNPP Resolution Plan Appropriate surrogate materials will need to be selected for the chemical effects tests.

Item 3.11: Advanced Metallic Corrosion Understanding The PJRT panel raised several other issues related to the understanding ofmetallic corrosion in the post-LOCA environment These issues include enhanced Al corrosion caused by hypochlorite or other catalytic effects (e.g., jet impingement), synergistic effects on corrosion, and corrosion inhibition.

These effects could substantially affect corrosion rates and therefore could have different effects on ECCS sump head loss.

Page A-20 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 The following root issues are contained in this item:

1. Enhanced corrosion due to acid formation.

2. Enhanced corrosion due to pitting from jet impingement.

3. Synergistic effects on corrosion.

4. Corrosion inhibition.

As discussed previously, the long-term effects on pH due to acid formation may be an important factor that should be considered. Also as discussed previously, pitting from jet impingement is considered to be an insignificant factor due to the localized impact ofthe jet. Generally, synergistic effects tend to inhibit corrosion, but both synergistic effects and corrosion inhibition are inherently considered in integrated testing.

CCNPP Resolution Plan Appropriate synergistic effects and corrosion inhibition are addressed due to the selection of materials in the proper proportions relative to the CCNPP containment, as described in Item 1.1. Acid formation is addressed in Item 2.1 Item 3.12: Submerged Source Terms: Biological Growth in Debris Beds The PIRT considered the propensity for bacteria or other biota to grow in preexisting debris beds located on the sump strainer screen or elsewhere within the EGGS system. Significant bacterial growth may be important ifit creates additional debris that contributes to sump screen clogging or detrimental performance ofdownstream components like pumps and valves.

The following root issue is contained in this item:

1. Biological growth in the post-LOCA environment may contribute to clogging issues.

As discussed in the March 2011 report, most microorganisms cannot survive under high temperature, low or no light, and high radiation conditions. Any microorganisms that do survive would be highly unlikely to experience significant growth under the harsh post-LOCA conditions.

Therefore, biological effects can be reasonably neglected for a realistic chemical-effects analysis.

CCNPP inspected the containment sumps and observed no biologic growth. One of the radiation protection individuals at CCNPP has inspected containment sumps at mUltiple plants and cleaned two of them. In none of these cases was biologic growth observed.

Page A-21 ofA-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-81S7-001 Revision 0, November 16, 2012 CCNPP Resolution Plan This item will not be addressed in chemical effects tests.

Item 3.13: Reactor Core: Fuel Deposition Spall Spall ofreactor fuel cladding oxides (Zr02) and deposited chemical products could be a potential source ofactivated materials that could affect chemical reactions in the post-LOCA containment pool.

Also, precipitates ofpost-LOCA chemical products (organics, AI, B, Ni, Fe, Zn, Ca, Mg, silicates (SiOr and Si044), and COr--based products) could deposit on the fuel clad and spall, contributing either to clogging within the reactor core, or head loss across the sump strainer.

The following root issues are contained in this item:

1. Spall of activated fuel cladding oxides could affect chemical reactions in the containment pool.

2. Precipitation and spall of chemical products on the fuel could contribute to fuel or strainer clogging.

As discussed previously, the effect of activated particles on chemical effects due to radiolysis is considered to be insignificant. However, this debris could contribute to the source term for particulate debris with an effect on the overall head loss across the strainer or fuel channels. This issue is addressed in Item 3.1.

Some precipitates, particularly certain calcium precipitates, exhibit retrograde solubility. As water flows through the reactor vessel, the high temperature in the vicinity of the fuel rods may cause some of these materials to precipitate. The precipitates may form on the fuel rods themselves, or in solution where they can be swept out of the reactor vessel and potentially contribute to strainer clogging. This is a potentially significant issue that needs to be addressed for materials that exhibit retrograde solubility.

CCNPP Resolution Plan The effects of chemical precipitation on the fuel rods have been previously addressed in a conservative manner for CCNPP using the LOCADM software. Precipitation of materials with retrograde solubility in the bulk solution within the reactor core will be addressed in bench-Page A-22 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 scale tests based on the concentration, core temperature, and solubility limit for potential precipitates.

Item 4.1: Polymerization The PIRT panelists expect polymerization to occur after molecular precipitation as a precursor to solid species agglomeration in post-LOCA environments. Molecular precipitation refers to the formation of bonds between metallic species and oxygen to form monomers. Polymerization is the ripening ofthese bonds to form covalent bonds and the growth ofthe monomers through one ofmany types of polymerization reactions. Chain polymerization, which is the most common, consists ofinitiation and propagation reactions and may include termination and chain transfer reactions. Step-growth and condensation polymerization are two additional mechanisms. Polymerization occurs until approximately nanometer-sized particles have formed. These particles can then continue to grow to larger sizes through agglomeration mechanisms.

The PIRT panelists expect polymerization is needed to form large enough particles to tangibly affect ECCS performance. The fact that chemical precipitates have formed during testing to simulate post LOCA conditions provides evidence that polymerization is likely occurring. The issue is important only ifthe differences in polymerization mechanisms in the simulated and actual post-LOCA environments are significant enough to alter head loss or downstream effects associated with the chemical precipitates.

The following root issue is contained in this item:

1. Polymerization processes may cause initial precipitate growth.

As discussed in the March 2011 report, polymerization is expected to be an important process in the formation of precipitates, but is appropriately represented in testing and does not need to be further evaluated.

CCNPP Resolution Plan No action required.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 4.2: Heat Exchanger: Solid Species Formation Chemical species having normal solubility profiles may be dissolved in the containment pool at higher temperatures. However, these chemical species may precipitate in the heat exchanger because ofa drop in temperature ofapproximately 30 degrees F. Some possible solid species that could form include AI(OHh FeOOH, and amorphous SiDz. The lower temperature at the heat exchanger outlet could also facilitate the development ofmacro scale coatings or suspended particulates, or both, that can continue to transport in the circulating fluid. Possible implications ofthis scenario include (1) species remain insoluble at higher reactor temperatures and affect the ability to cool the reactor core, (2) solid species formed may clog the reactor core and degrade heat transfer from the fuel, (3) species remain insoluble at higher containment pool temperatures and cause additional head loss upon recirculation, and (4) particulates act as nucleation sites for other compounds to precipitate.

The following root issue is contained in this item:

1. The temperature drop at the heat exchanger may reduce the solubility limit sufficiently to cause precipitate formation.

This is a potentially significant issue that should be evaluated in the chemical effects testing.

Timing is an important factor here. Early in the event while the pool temperatures are hot, the temperature drop across the heat exchangers may be significantly higher than 30°F. Since it takes time for containment materials to corrode and dissolve, precipitation may not be possible until much later in the event when the concentration in the pool starts to approach the solubility limit.

Timing may also be important with respect to the kinetics of precipitate formation since the duration that coolant flow is exposed to lower temperatures downstream of the heat exchangers is relatively brief.

CCNPP Resolution Plan The final portion of the tests will be used to investigate low temperature chemical effects by reducing the temperature in stages until room temperature is achieved.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 4.3: Reactor Core: Precipitation The increased temperature in the reactor vessel (i.e., 70 degrees C higher than the containment pool) and retrograde solubility ofsome species (e.g., Ca silicate, Ca carbonate, zeolite, sodium calcium aluminate) causes precipitation and additional chemical product formation. This could result in the following: (1) additional precipitate could be created and transported to the sump screen that would then contribute to head loss and (2) precipitate or spall (see Section 3.13 ofthis report) passing through the sump screen may degrade the performance ofECCS components downstream from the screen.

The following root issue is contained in this item:

1. High localized temperatures in the reactor vessel may cause precipitation of materials with retrograde solubility.

This is a potentially significant issue that should be evaluated in chemical effects testing. It should be noted, however, that the bulk flow temperature in the reactor vessel would generally not be 70°C (158°F) higher than the pool temperature. It is possible for local temperatures within the core (Le.

next to the fuel cladding) to be significantly hotter than the pool, which could result in localized precipitation. Also, under certain scenarios (such as a cold leg break during cold leg injection), it is possible for the water in the core to boil. Even under these conditions, however, the maximum bulk temperature in the core would be limited to the saturation temperature, which would never approach a level that is 158°F hotter than the pool. Therefore, the focus of this issue should be on localized high temperatures in the reactor vessel rather than overall high temperatures in the bulk flow.

CCNPP Resolution Plan An investigation of existing literature will be performed to evaluate the possible effects of retrograde solubility, and thermodynamic software may be used to identify possible species that may exhibit retrograde solubility. In addition, this item may be explored in bench-scale testing.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 4.4: Particulate Nucleation Sites Particles within containment create the nucleation sites required for chemical precipitation.

Examples ofparticles that could serve as nucleation sites include irradiated particles, dirt particles, coating debris, insulation debris, biological debris, and other materials within the post-LOCA containment pool. These particles then grow through polymerization (see Section 4.1 ofthis report) and agglomeration (see Sections 5.1 and 6.2 ofthis report) into solid species that are large enough to possibly degrade ECCS performance.

This issue identifies a fundamental aspect ofthe formation ofsolid species. Implications only arise if the nucleation sites in the post-LOCA environment are not appropriately simulated in testing. That is, the quantities and types ofnucleation sites used in testing should be representative ofthe post-LOCA environment to ensure that solid species formation is not suppressed.

The following root issue is contained in this item:

1. Heterogeneous nucleation sites are required for precipitation to occur.

As discussed in the March 2011 report, both containment and test conditions contain numerous nucleation sites. Therefore, this is not a significant issue.

CCNPP Resolution Plan No action required.

Item 4.5: Coprecipitation I

NRC I

I Industry I Position "V Position "V Coprecipitation occurs when a normally soluble ion becomes either included or occluded into the crystalline structure ofa particle ofinsoluble material. Precipitation ofone species could lead to increased precipitation ofanother species (which iftaken separately, are each below their solubility limit). Thus, more solid species could form, which could lead to a greater concentration ofchemical precipitates at the sump strainers or downstream ofthe strainers. Additionally, the species thatform could differ in size from those observed in the ICET tests (i.e., 1 to 100 microns) such that they affect the head loss at the sump strainer more significantly.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 The following root issue is contained in this item:

1. Precipitation of one material may result in precipitation of another material that would not otherwise have precipitated.

Coprecipitation does not reduce the solubility limit of precipitates, and therefore would not cause precipitation of two materials that are both below their solubility limit as suggested above.

Although it is a potentially significant issue, in an integrated test environment, the various reactive materials are present together and coprecipitation can occur naturally. Therefore, this issue is inherently included in an integrated test.

CCNPP Resolution Plan The issue of coprecipitation is addressed by inclusion of all materials that participate in chemical reactions in the same proportions that they are present at CCNPP, as described in Item 1.1.

1tem 5.1: Inorganic Agglomeration Inorganic agglomeration is the formation oflarger clumps ofsmaller particulates. This phenomenon depends upon the pH ofthe point ofzero charge (PZC) ofthe species and the ionic strength (the higher the ionic strength, the smaller the distance for agglomeration) ofthe fluid. This phenomenon is sensitive to many factors, including particle shape factors, and maximum particle size. Inorganic agglomeration ofsmall particles into larger sized particulates could degrade strainer performance.

The following root issue is contained in this item:

1. Agglomeration of chemical precipitates, insulation particulate, and/or latent particulate may form larger particles that would be more easily captured in a debris bed.

In general, agglomeration of particles will make the debris less transportable. Also, as shown in NUREG/CR-6224, smaller particles have a larger impact on head loss due to the larger surface-to volume ratio. Therefore agglomeration of particulate debris with each other or chemical preCipitates is not a significant issue.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 CCNPP Resolution Plan No attempt to either stimulate or prevent agglomeration of particles will be incorporated into the chemical effects tests. In the chemical effects tests, particulate debris will be pre-deposited in the debris beds and will not be circulating in the solution in significant quantities. The solution chemistry in the chemical effects tests will be similar to the CCNPP system, so the formation and behavior of chemical precipitates will be similar, with particulate debris already present in the debris bed.

Item 5.2: Deposition and Settling Chemical products formed in the post-LOCA containment environment could either settle within the containment pool or be deposited on other surfaces. Chemical species which attach to or coat particulate debris may enhance settling. Examples are aluminum coating on NUKON fiber shifting the PZC or formation ofa hydrophobic organic coating. This could result in less particulate debris and chemical product transporting to the sump screen and either accumulating on or passing through it.

The possible implications ofthis issue are that the chemical precipitates added to the plant-specific chemical effects tests could result in increased settling during the tests compared to actual plant conditions.

The following root issue is contained in this item:

1. Chemical precipitates may settle or enhance settling of other particulate in the containment pool.

Given their small size, chemical precipitates can readily transport under relatively low flow conditions, and it is not expected that significant settling would occur. Therefore, this is not considered to be a significant issue.

CCNPP Resolution Plan No action required.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 5.3: Quiescent Settling of Precipitate Quiescent flow regions within the containment pool promote settling. The low flow rate within most of the containment pool also allows larger size, more stable particles and precipitates to form, which promotes settling. Settling ofnonchemical debris and precipitate could be beneficial with respect to the pressure drop across the sump strainer.

The following root issue is contained in this item:

1. Chemical precipitates may settle or enhance settling of other particulate in the containment pool.

As discussed above, this is not considered to be a significant issue.

CCNPP Resolution Plan No action required.

Item 5.4: Transport Phenomena: Precipitation and Coprecipitation Precipitation or coprecipitation and ripening ofsolid species within the containment pool would create solid species which are less likely to transport. Decreased transportability will result in less product migrating to or through the sump screen.

The following root issue is contained in this item:

1. Chemical precipitates may settle in the containment pool.

As discussed above, this is not considered to be a significant issue.

CCNPP Resolution Plan No action required.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 6.1: Break Proximity to Organic Sources The pipe break location plays an important role in debris generation. If the break occurs in close proximity to organic sources, it could introduce a significant amount oforganic materials into the containment pool. Organic sources could then affect the nature, properties, and quantities ofchemical byproducts that form in the post-LOGA containment environment. The scenario evaluated by the PIRT considered failure or leakage ofoil and other organics from either the RGP oil collection tanks or lube oil systems resulting from LOGA-induced damage. If the pipe break occurs in close proximity to the organic sources, up to approximately 250 gallons ofoil may be released to the containment pool. If this should occur, head loss and downstream effects may be altered, either beneficially or negatively, by these organic materials.

The following root issues are contained in this item:

1. Certain breaks may result in a significant quantity of oil being released into the containment pool.

2. Other organic materials may be present due to failure of coatings and the organic binders in insulation debris.

As discussed in the March 2011 report, one licensee added a large quantity of oil (representative of the quantity from one RCP motor) to an integrated chemical effects head loss test. The oil addition had no impact on the head loss, and is not considered to be a significant factor.

Similarly, the presence ofsmaller quantities of organic material from other sources is not expected to have a significant effect on the pool chemistry conditions.

CCNPP Resolution Plan The cases where a significant quantity of oil would be introduced to the containment pool would be limited to a few larger breaks in the vicinity of one of the RCP motors. Since the majority of break cases would not have significant quantities of oil, oil will not be included in the 30-day chemical effects tests. The issue of organic materials from coatings failure and organic binders in insulation debris is addressed in Item 6.4, below.

Page A-30 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16,2012 Item 6.2: Organic Agglomeration Organic agglomeration is the process ofsmall organic colloidal particles (1 to 100 nanometers in size) joining together, or coagulating, to form larger particles and precipitates. Coagulated particles can collect on sump strainers, decreasing ECCS flow; they could also collect on other wetted surfaces, such as walls or structural steel, and decrease the debris loading on the sump screen. Hence, head losses and downstream effects could differ from those evaluated during plant-specific testing.

The following root issue is contained in this item:

1. Organic agglomeration may form larger particles that would be more easily captured in a debris bed.

As discussed in the March 2011 report, this issue is similar to the issue of inorganic agglomeration, and is not considered to be a significant factor.

CCNPP Resolution Plan The resolution of this item is the same as Item 5.1.

Item 6.3: Organic Complexation OrganiC complexing agents act to inhibit agglomeration either by adsorption onto solid surfaces or by interaction in solution with metal ions. Organic surface complexation occurs iforganiC molecules (i.e.,

amines, acids, and heterocycles) adsorb on surfaces ofions or solids and inhibit the subsequent precipitation orgrowth ofthose species. The implications oforganic complexation are counter to those associated with organiC agglomeration. OrganiC complexation could reduce the effects associated with chemical precipitates and therefore may be beneficial to ECCS performance ifthis phenomenon is not credited or addressed during plant-specific testing.

The following root issue is contained in this item:

1. Organic complexation may inhibit agglomeration.

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Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Since both inorganic and organic agglomeration are not considered to be significant issues, organic complexation would be an insignificant factor also.

CCNPP Resolution Plan No action required.

Item 6.4: Coating Dissolution and Leaching Coatin9s existin9 within containment represent possible additional physical debris sources. Generally conservative 9uidance for considerin9 the effects ofphysical coatin9 debris is providedfor the evaluation ofECCS performance. However, dissolution and leachin9 ofcoatin9s can impact the chemical effects that occur within, or are transported to, the ECCS coolin9 water. Both inor9anic (e.9.,

zinc-based) and or9anic (e.9., epoxy-based) coatin9s exist within containment. One concern is that these coatin9s leach chemicals as a result ofbein9 submerged in the containment pool environment after the LOCA. Coatin9s may create additional chemical species (e.9., chlorides or or9anics) within the containment pool that could potentially increase sump screen head loss or promote more deleterious downstream effects.

The following root issue is contained in this item:

1. Materials may leach from coatings affecting the overall pool chemistry.

As discussed in the March 2011 report, the amount of material that dissolves or leaches from coatings is expected to be relatively low. However, this is a potentially significant issue and should be appropriately addressed in realistic testing.

CCNPP Resolution plan Existing literature will be reviewed to assess the rates of leaching from coated surfaces. If necessary, information from literature can be supplemented with data from bench-scale testing. Ifthe literature or bench-scale testing indicates that leaching from coatings can affect the overall pool chemistry, appropriate materials will be included in the chemical effects tests.

Page A-32 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 7.1: Emergency Core Cooling System Pump: Seal Abrasion and Erosion or Corrosion Abrasive wearing ofpump seals (e.g., magnetite-high volume or concentration ofmild abrasive) creates additional materials that contribute to containment pool chemistry. In addition, chemical byproducts cause erosion or corrosion ofpump internals, especially close-clearance components (e.g.,

bearings, wear rings, impellers). The possible implications ofthese phenomena are (1) additional particles could contribute to reactor core clogging, (2) particles could add additional sump screen loading, (3) particles could affect chemical species formation, and (4) pump performance degrades, possibly to the point ofbeing inoperable.

The following root issue is contained in this item:

1. Particulate debris generated by abrasive wearing of pump seals may cause additional downstream problems.

As discussed in the March 2011 report, the quantity of particulate material generated by wearing of the pump seals is insignificant compared to other particulate sources. Also, the pump materials are not unique, and the surface area of similar metals and materials in containment are large enough that the impact of the pump internals on chemical effects is considered to be negligible. Therefore, this issue is insignificant.

CCNPP Resolution Plan No action required.

Item 7.2: Heat Exchanger: Deposition and Clogging Solid species which form in the heat exchanger lead to surface deposition or clogging, or both, within close-packed heat exchanger tubes (SIB-inch in diameter). This could cause decreased flow through the heat exchanger core or diminished heat transfer between the ECCS and heat exchanger cooling water, or both. Diminished cooling ofthe ECCS water could ultimately decrease the capacity ofthe ECCS water to remove heatfrom the reactor core.

Page A-33 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 The following root issue is contained in this item:

1. Precipitation within the heat exchanger may affect the heat exchanger performance.

As discussed in the March 2011 report, chemical precipitates would not have enough shear strength to block flow through the heat exchanger tubes. It's possible that some precipitates could create a thin coat on the tube walls. However, since the precipitates would generally form later in the event when the heat exchangers have ample margin, any slight degradation in performance due to the precipitates is negligible.

CCNPP Resolution Plan The efficiency of heat exchange and performance of the heat exchangers will not be monitored during the chemical effects tests. However, if the heat exchanger used in the test can be disassembled, the heat exchanger tubes will be visually inspected for the presence of precipitates or scale formation, and if precipitates or scale is present, a sample of the precipitates will be scraped from the surfaces and analyzed using the techniques used for precipitate analysis.

Item 7.3: Reactor Core: Fuel Deposition and Precipitation The increased temperature (+ 70 degrees Cfrom containment pool) and retrograde solubility ofsome species (e.g., Ca silicate, Ca carbonate, zeolite, sodium calcium aluminate) causes scale buildup on the reactor core. Zn, Ca, Mg, and COrbased deposits, films, and precipitates may form at higher temperatures within the reactor core. This may lead to (1) a decrease in heat transfer from the reactor fuel, (2) localized boiling due to insufficient heat removal, and (3) spallation ofdeposits, creating additional debris sources which could clog the reactor core or contribute to sump screen head loss.

The following root issue is contained in this item:

1. High localized temperatures in the reactor vessel may cause precipitation of materials with retrograde solubility.

As discussed previously, precipitation of materials with retrograde solubility on the fuel surfaces or in solution within the core is a significant issue that needs to be addressed.

Page A-34 ofA-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 CCNPP Resolution Plan The resolution for this item is the same as the resolution for Item 3.13 and Item 4.3.

Item 7.4: Reactor Core: Diminished Heat Transfer Physical and chemical solid debris within the ECCS coolant water could diminish the fluid's heat transfer capacity and degrade the ability ofthe coolant to remove heatfrom the core.

The following root issue is contained in this item:

1. Concentrated materials in the reactor vessel may reduce the water's heat removal capacity.

The highest debris concentrations would occur under cold leg break conditions during cold leg injection since the water entering the core would boil off raising the concentration of boron, other dissolved materials, and suspended solids. As discussed in the March 2011 report, the relatively dilute concentration of dissolved solids would not significantly affect the rate of boiling and rate of heat removal. The effects of high boron concentration on heat removal are not fully understood, but a PWROG program investigating this issue is currently in progress and is expected to be completed by 2015. Although the outcome ofthe PWROG research may change the acceptable limit for boron concentration in the reactor vessel, it would not affect the physical processes that must be evaluated in realistic chemical effects testing. Therefore, the PWROG progress should be monitored for potential plant modifications that may be required (Le. timing for switchover from cold leg to hot leg injection), but is not a significant issue for realistic chemical effects testing.

At the chemical effects summit, the NRC announced that the boron precipitation issue must now be addressed as part ofthe overall resolution of GSI -191.

CCNPP Resolution Plan The resolution of the boron precipitation issue will not be addressed in the CCNPP chemical effects test program. This issue will be addressed as part of the overall resolution of GSI-191 at CCNPP.

Page A-35 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-8157-001 Revision 0, November 16, 2012 Item 7.5: Reactor Core: Blocking of Flow Passages Fuel deposition products and precipitated retrograde soluble chemical species spall and settle within the reactor vessel. Settling can be potentially deleterious ifflow passages to the fuel elements are either globally or locally impeded. Reduced flow within the RPV, ifsignificant, has the potential to diminish heat transfer from the fuel.

The following root issue is contained in this item:

1. Debris may spall and settle within the reactor vessel causing blockage.

As discussed previously, precipitates that form due to retrograde solubility within the reactor vessel must be properly addressed. This item raises an additional issue of the potential settling of precipitates or other debris spall under low flow conditions within the reactor vessel. During cold leg injection, the flow would move upward through the core and would tend to lift the debris and transport it out of the reactor vessel. If the settling velocity is high enough for the debris to settle, it would not be expected to create any significant head loss since the flow would simply have to overcome the "weight" of the debris to continue injecting into the core. During hot leg injection, the flow would move downward through the core in the same direction that settling debris would be moving. The debris could accumulate in various locations where it could form a bed and cause higher head losses. However, this issue would occur regardless of debris settling. Therefore, debris settling concerns are insignificant for realistic chemical effects testing.

CCNPP Resolution Plan No action required.

Item 7.6: Reactor Core: Particulate Settling Relatively low, upwards flow (for cold leg injection) within the reactor causes particulates to settle.

Compacted deposits form and may impede heat transfer and waterflow, especially for lower portions ofreactor fuel.

Page A-36 of A-37

Chemical Effects Head Loss Considerations for Calvert Cliffs Nuclear Power Plant CCNPP-81S7-001 Revision 0, November 16, 2012 The following root issue is contained in this item:

1. Particulate debris may settle during cold leg injection causing flow path blockage or inhibiting heat transfer.

As discussed previously, debris that settles during cold leg injection would not result in significant head loss. Also, as discussed in the March 2011 report, the higher flow through the core for a hot leg break, and the turbulence due to boiling for a cold leg break would be expected to keep the particulate debris from blocking heat transfer to the lower portions of the fuel. Therefore, debris settling concerns are insignificant for realistic chemical effects testing.

CCNPP Resolution Plan No action required.

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ML13030A348 OFFICE DORLILPLI-1/PM DORLILPLI-1/LA DE/ESGB/BC DSS/SSIB/BC DORLILPLI-1/BC NAME NMorgan KGoldstein GKulesa SBailey GWilson 02/04/13 02/01/13 02/06/13 02/05/13 02/07/13

v t e Letter Sequence Meeting
TAC:MC4672, (Open) TAC:MC4673, (Open)
Initiation Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request Acceptance... Supplement, Supplement Administration Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting Questions 31 May 2005 3 June 2005 9 February 2006 4 December 2008 12 April 2010 Answers 15 July 2005 10 November 2010 Results Approval... Other: ML060950051, ML061870222, ML062640547, ML063340702, ML071270372, ML081130739, ML082740497, ML102930650, ML13086A551
MONTHYEAR2010-06-07 [Table View]

ML13030A348

Text

SUBJECT:

SUMMARY

Enclosure:

1.0 INTRODUCTION

2.0 BACKGROUND

7.0 CONCLUSION

8.0 REFERENCES

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