ML13086A551

Calvert Cliffs, Units 1 and 2, MC4672 & MC4673 - CCNPP-CHLE-003, Rev 0c Chemical Effects Pirt Considerations Excerpts with Respect to GL2004-02, GSI-191

ML13086A551
Person / Time
Site:	Calvert Cliffs
Issue date:	01/24/2013
From:	Sellers C D - No Known Affiliation
To:	Office of Nuclear Reactor Regulation
References
TAC MC4672, TAC MC4673, GL-04-002, GSI-191
Download: ML13086A551 (1)

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Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Oc, January 30, 2013CCNPP Resolution Plan_Coating dissolution and leaching will be addressed bh including scaled surface areas of coupons -.- Deletd: Existing literature will be reviewed to...assess the rates of leaching from coated surfaces.coated with CCNPP-specific qualified and unqualified coatings in the test chamber. If necessary, information from literature can besupplemented with data from bench-scale testing.If the literature or bench-scale testing indicates7.0 CHEMICAL EFFECTS ON DOWNSTREAM SYSTEM PERFORMANCE: PUMPS, HEAT that leaching from coatings can affect the overallpool chemistry, appropriate materials will beEXCHANGERS, AND REACTOR CORE included in the chemical effects tests7.1 Emergency Core Cooling System Pump: Seal Abrasion and Erosion or CorrosionNRC IndustryPosition X PositionAbrasive wearing of pump seals (e.g., magnetite-high volume or concentration of mild abrasive)creates additional materials that contribute to containment pool chemistry. In addition, chemicalbyproducts cause erosion or corrosion of pump internals, especially close-clearance components (e.g.,bearings, wear rings, impellers). The possible implications of these phenomena are (1) additionalparticles could contribute to reactor core clogging, (2) particles could add additional sump screenloading, (3) particles could affect chemical species formation, and (4) pump performance degrades,possibly to the point of being inoperable.The following root issue is contained in this item:1. Particulate debris generated by abrasive wearing of pump seals may cause additionaldownstream problems.As discussed in the March 2011 report, the quantity of particulate material generated by wearing ofthe pump seals is insignificant compared to other particulate sources. Also, the pump materials arenot unique, and the surface area of similar metals and materials in containment are large enoughthat the impact of the pump internals on chemical effects is considered to be negligible. Therefore,this issue is insignificant.CCNPP Resolution PlanNo action required.Page 33 of 37 CHEMICAL EFFECTS PIRT CONSIDERATIONS forCalvert Cliffs Nuclear Power PlantCCNPP-CHLE-003, Revision ObJanuary 24, 2013Prepared by:Craig D. SellersReviewed by:Stephen KinseyReviewed by:Timothy D. Sande Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013REVISION HISTORY LogRevision DescriptionOb Issue for NRC Review-ii Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013Contents1.0 Underlying Containm ent Pool Chem istry ................................................................................................ 41.1 RCS coolant chem istry conditions at break ....................................................................................... 41 .2 p H V a ria b ility ......................................................................................................................................................... 51.3 Hydrogen Sources w ithin Containm ent ................................................................................................ 61.4 Containm ent spray CO2 scavenging and C02/02 air exchange ..................................................... 71.5 Em ergency Core Cooling System Injection of Boron ...................................................................... 72.0 Radiological Considerations ................................................................................................................................. 82.1 Radiolytic Environm ent ......................................................... ................. ............. .................................. 82.2 Radiological Effects: Corrosion Rate Changes ..................................................................................... 92 .3 H y d ro ly s is ............................................................................................................................................................. 1 02.4 Conversion of N2 to HN03 ............................................................................................................................... 102.5 Additional Debris Bed Chem ical Reactions ....................................................................................... 113.0 Physical, Chem ical, and biological debris source term s ................................................................... 123 .1 C ru d R e le a se ......................................................................................................................................................... 1 23 .2 Jet Im p in g e m e n t ................................................................................................................................................. 1 33.3 Debris M ix Particulate/Fiber Ratio ............................................................................................................. 143.4 Effects of Dissolved Silica from RCS and RW T ................................................................................. 153.5 Containm ent Spray Transport ...................................................................................................................... 163.6 Initial Debris Dissolution ................................................................................................................................ 173.7 Subm erged Source Term s: Lead Shielding ....................................................................................... 173.8 Subm erged Source Term s: Copper ............................................................................................................. 183.9 Concrete M aterial Aging .................................................................................................................................. 193 .1 0 A llo y in g E ffe cts .................................................................................................................................................... 2 03.11 Advanced M etallic Corrosion Understanding .................................................................................. 213.12 Subm erged Source Term s: Biological Growth in Debris Beds .................................................. 213.13 Reactor Core: Fuel Deposition Spall ..................................................................................................... 224,0 Solid Species precipitation .................................................................................................................................. 234 .1 P o ly m e riza tio n .................................................................................................................................................... 2 34.2 Heat Exchanger: Solid Species Form ation .......................................................................................... 244.3 Reactor Core: Precipitation ............................................................................................................................ 254.4 Particulate Nucleation Sites ........................................................................................................................... 264 .5 C o p re c ip ita tio n .................................................................................................................................................... 2 75,0 Agglom eration and Settling: Chem ical Effects .................................................................................... 275.1 Inorganic Agglom eration ................................................................................................................................ 275.2 Deposition and Settling .................................................................................................................................... 285.3 Quiescent Settling of Precipitate .................................................................................................................. 29ii Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20135.4 Transport Phenomena: Precipitation and Coprecipitation ....................................................... 296 .0 O rg a n ics a n d C o a tin g s ........................................................................................................................................... 3 06.1 Break Proximity to Organic Sources .................................................................................................. 306 .2 O rgan ic A gglom eration ................................................................................................................................... 3 16 .3 O rgan ic C o m p lexatio n ...................................................................................................................................... 3 16.4 Coating D issolution and Leaching ............................................................................................................... 327.0 Chemical Effects on Downstream System Performance: Pumps, Heat Exchangers, andR e a c to r C o re ............................................................................................................................................................................ 3 37.1 Emergency Core Cooling System Pump: Seal Abrasion and Erosion or Corrosion ........... 337.2 Heat Exchanger: Deposition and Clogging ........................................................................................ 347.3 Reactor Core: Fuel Deposition and Precipitation ............................................................................ 347.4 Reactor Core: Diminished Heat Transfer .......................................................................................... 357.5 Reactor Core: Blocking of Flow Passages .......................................................................................... 367.6 R eactor Core: Particulate Settling ............................................................................................................... 37List of TablesTable 1: Summary of NRC and Calvert Cliffs Positions on Chemical Effects PIRT Items ..................... 2iii Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013Resolution of Outstanding Chemical Effects PIRT IssuesIn March 2011, the Office of Nuclear Reactor Regulation issued a document titled "Evaluation ofChemical Effects Phenomena Identification and Ranking Table Results". This documentsummarized 42 potentially significant issues that required further evaluation based on an originallist of over 100 chemical effects phenomena identified in NUREG-1918, "Phenomena Identificationand Ranking Table Evaluation of Chemical Effects Associated with Generic Safety Issue 191". TheNRC provided an evaluation of the remaining 42 issues in the March 2011 report, and dispositionedeach item as either having a negligible impact on the results or having been adequately addressedin the current plant-specific analyses. In several cases, issues that were not directly addressed bythe industry were considered acceptable based on conservatisms in the methodology used for theplant-specific analyses.In an effort to understand the true impact that chemical effects could have on long-term corecooling in a plant-specific post-LOCA environment, several plants are considering the option ofperforming chemical effects testing that is more realistic than previous tests. Since the testing willattempt to reduce or eliminate overly-conservative methods that were used previously, it is alsonecessary 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 PIRTissues. The purpose of this assessment is to provide discussion points for the industry and the NRCto reach agreement on the conditions that must be explicitly modeled in realistic chemical effectstests.During the NEI Chemical Effects Summit on January 26th and 27th, 2012, the initial revision of thisdocument was presented and the resolution for each PIRT issue was discussed with the NRC andindustry. Table 1 provides a list of each issue with the current NRC and industry positions based onthe 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 mustbe incorporated or can be excluded from realistic testing. Future discussions should focus onpotential areas of disagreement, and the objective of these discussions should be two-fold:0 Ensure that significant phenomena are properly addressed0 Avoid using limited resources to test insignificant phenomenaPage 1 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013Table 1: Summary of NRC and Calvert Cliffs Positions on Chemical Effects PIRT Items'%F indicates a significant issue that must be addressed in realistic chemical effects testingX indicates an insignificant issue that can be neglected for chemical effects testingItemPhenomenonNRC IndustryPosition Position1.0 Underlying Containment Pool Chemistry1.1 RCS coolant chemistry conditions at break u M1.2 pH variability M O1.3 Hydrogen sources within containment x x1.4 Containment spray CO2 scavenging and C02/02 air exchange1.5 ECCS injection of boron Moo2.0 Radiological Considerations2.1 Radiolytic environment 'V2.2 Radiological effects: corrosion rate changes2.3 Hydrolysis x x2.4 Conversion of N2 to HNO32.5 Additional debris bed chemical reactions3.0 Physical, Chemical, and Biological Debris Source Terms3.1 Crud release3.2 Jet impingement x3.3 Debris mix particle/fiber ratio M -*3.4 Effects of dissolved silica from RCS and RWST Moo3.5 Containment spray transport3.6 Initial debris dissolution M3.7 Submerged source terms: lead (Pb) shielding Moor3.8 Submerged source terms: copper (Cu) M60 M3.9 Concrete material aging x x3.10 Alloying effects Moor3.11 Advanced metallic corrosion understanding Ir3.12 Submerged source terms: biological growth in debris beds3.13 Reactor core: fuel deposition spallingPage 2 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20131Z indicates a significant issue that must be addressed in realistic chemical effects testingX indicates an insignificant issue that can be neglected for chemical effects testingItem Phenomenon NRC IndustryPosition Position4.0 Solid Species Precipitation4.1 Polymerization X X4.2 Heat exchanger: solid species formation /4.3 Reactor core: precipitation4.4 Particulate nucleation sites4.5 Coprecipitation5.0 Agglomeration and Settling: Chemical Effects5.1 Inorganic agglomeration5.2 Deposition and settling5.3 Quiescent settling of precipitate IX5.4 Transport phenomena: precipitation/coprecipitation X6.0 Organics and Coatings6.1 Break proximity to organic sources X6.2 Organic agglomeration6.3 Organic complexation6.4 Coating dissolution and leaching7.0 Chemical Effects on Downstream System Performance7.1 ECCS pump: seal abrasion and erosion/corrosion X7.2 Heat exchanger: deposition and clogging7.3 Reactor core: fuel deposition and precipitation7.4 Reactor core: diminished heat transfer7.5 Reactor core: blocking of flow passages7.6 Reactor core: particulate settlingThe following discussion provides additional details of the specific issues and how they should beaddressed. The italicized text was copied directly from the NRC's March 2011 report describing the42 issues.Page 3 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20131.0 UNDERLYING CONTAINMENT POOL CHEMISTRY1.1 RCS coolant chemistry conditions at breakNRC Industry Position PositionThe reactor coolant system (RCS) coolant chemistry varies over the fuel cycle. Boron concentrationsvary from approximately 2,000 to 4,000 parts per million (ppm) at the beginning of the fuel cycle.Therefore, the initial reactor water chemistry spewing out of the break and forming the containmentpool will have variable boron concentration while the ratio of lithium to boron is approximatelyconstant. The two-phase jet emanating from the break is initially at 315 degrees Celsius (C) (599degrees Fahrenheit (F)) and then cools to 120 degrees C (248 degrees F). The main concern raised bythe peer reviewers relates to how variations in the initial RCS chemistry will affect the interaction withcontainment materials and whether these variations have been appropriately addressed. Variationsmay influence corrosion rates of metals, leaching of species from nonmetallic materials, formation ofchemical 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 differenteffects.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 of the 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 effectsissues associated with impact by the break jet are negligible. After the blowdown phase ends, thewater from the break would simply spill into the pool with minimal contact of containmentmaterials.Boron concentration is an important factor for chemical effects-partly due to potential chemicalreactions, and partly due to its effect on pH. Therefore, a realistic boron concentration should beused to determine a realistic pH level, and an appropriate concentration should be added at thestart of an integrated test. The RCS boron concentration at CCNPP ranges from approximately2,700 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 isgenerally low (ranging from negligible quantities to a few ppm). However, since it is relatively easyPage 4 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013to include, a representative concentration of lithium should be added at the start of an integratedtest.Temperature is an important factor since it has a direct effect on corrosion rates and solubilitylimits. Therefore, a realistic analysis should take into consideration temperature variations overthe duration of the event.CCNPP Resolution PlanLong-term (30-day) tests will be run representing the bounding LOCA scenario that produces thelargest quantity of debris. The quantities of materials in the test will be determined from thequantities of materials determined to be in the CCNPP containment for the bounding break, asdetermined by break modeling. The boron and lithium concentrations for each test will be selectedby determining the concentrations in the RCS, RWST, and accumulators at CCNPP and calculatingthe concentration based on the contribution from each source for the LOCA scenario. The boronand lithium contributions from the RCS will be based on time-averaged concentrations. The impactof higher and lower concentrations of boron and lithium on the pH of the system will be evaluatedusing chemical equilibrium modeling. If the modeling indicates that changes in solution chemistrycause deviations in pH that significantly affect corrosion or precipitation rates, bench-scale testsmay be performed to investigate the rate of corrosion and extent of precipitation rates with higheror lower concentrations of boron and lithium. The temperature will be varied over the 30-dayduration to match the temperature profile of the break scenario, with the exception that the effectof corrosion at temperatures higher than 190 'F will be addressed by autoclave testing as discussedin Section Error! Reference source not found. of the main body of the paper.1.2 pH VariabilityNRC O 1 IndustryPosition PositionThe normal operating pH of the RCS is typically in the range of 6.9-74. The pH adjusted to 25 degreesC (77 degrees F) changes during the course of the fuel cycle from acidic at the beginning of the cycle tocloser to neutral by the end of a fuel cycle. There are implications similar to those discussed in Section1.1 of this report with respect to how pH variations may affect the interactions between containmentmaterials and the post-LOCA environment. These variations may influence corrosion rates of metals,leaching of species from nonmetallic materials, formation of chemical precipitates, and ultimatelyplant-specific chemical effects.Page 5 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013The 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 theresulting impact on the overall pH in the pool.CCNPP Resolution PlanThe normal operating pH of the RCS at CCNPP is 7.1. The issue of pH variability over the fuel cycleis addressed by the selection of boron and lithium concentrations in Item 1.1.1.3 Hydrogen Sources within ContainmentNRC IindustryPosition Position lDissolved hydrogen may play a significant role in the containment pool water chemistry. Hydrogensources within the containment include the RCS inventory; the corrosion of metallic materials,including the reactor fuel cladding; and the Schikorr reaction. Containment pool reduction-oxidation(redox) potential is afunction of the dissolved hydrogen resulting from these sources. Higher H2concentrations may decrease the redox potential. However, containment conditions are expected tofoster H2 evaporation, which could raise the redox potential. This issue could be important if H2concentrations 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 higherredox potential (i.e., more oxidizing) promotes metallic corrosion. As the concentration of dissolvedconstituents increases, so does the potential for solid species precipitation that could affect ECCSperformance. The NRC or industry testing has not attempted to accurately simulate post-LOCA H2concentrations. However, the Schikorr reaction, by itself, may be beneficial by converting compoundsthat 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 containmentpool.As discussed in the March 2011 review, H2 is considered insignificant since there will be limitedamounts of H2in solution, and higher concentrations could actually reduce potential corrosion.Page 6 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013CCNPP Resolution PlanNo action required.1.4 Containment spray CO2 scavenging and C02/02 air exchangeNRC Industry Position PositionAir entrainment within the containment pool beginning soon after the LOCA will cause carbon dioxide(CO2) absorption within the containment pool. This entrainment increases the amount of C02, whichcould produce higher carbonate precipitate concentrations than would otherwise be present. Theseprecipitates could also enhance nucleation and precipitation of other chemical species. Consequently,the air/liquid interactions within containment may increase the amount of chemical precipitates anddegrade ECCS performance more than if these interactions were not considered.The following root issue is contained in this item:1. Dissolved carbon dioxide may result in carbonate precipitates such as CaCO3.This is more of an issue for plants that do not use TSP as a buffer since dissolved calcium can reactwith the TSP to form calcium phosphate precipitates. As discussed in the March 2011 review, teststhat are open to the atmosphere would generally have a higher concentration of dissolved CO2 thanan air-tight containment. Therefore, although this is a potentially significant issue that should beconsidered for air-tight tests, no additional analysis is required for tests that are not air-tight.CCNPP Resolution PlanThe CCNPP chemical effects testing will be performed in a facility that is not air tight to ensure thatpotential formation of CaCO3 will be appropriately represented in the test conditions.1.5 Emergency Core Cooling System Injection of BoronNRC 1 IndustryPosition W Position WAfter a pipe break, RWST inventory with a boron concentration of approximately 2,800 ppm is injectedinto the RCS to cool the reactor core. This provides for a large boron source, which may affectchemical reaction products in the containment pool. Specifically, the boron source will serve as a pHPage 7 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision 0b, January 24, 2013buffer. This may influence corrosion rates of metals, leaching of species from nonmetallics, andultimately formation of chemical 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 chemicalreactions, and partly due to its effect on pH. Therefore, a realistic boron concentration should beused to determine a realistic pH level, and an appropriate concentration should be added at thestart of an integrated test. After a pipe break at CCNPP, RWST inventory with a boronconcentration between 2,300 and 2,700 ppm is injected into the RCS to cool the reactor core.CCNPP Resolution PlanThe concentration of boron to be used in the testing is addressed in Item 1.1.2.0 RADIOLOGICAL CONSIDERATIONS2.1 Radiolytic EnvironmentNRC Industry -Position PositionRadiolysis is the dissociation of molecular chemical bonds by a high energy radiation flux. The largestsource of this radiation flux is the gamma radioactive decay of the reactor fuel. When the ECCS fluidpasses through the reactor core, it is subjected to this radiation flux. Radiolysis reactions may changethe pH of the ECCS containment pool, the fluid's redox potential, or both. Hence, chemical specieswhich differ from those evaluated may form or the fluid may be more corrosive than that evaluated inall previous chemical effects testing.The following root issues are contained in this item:1. Radiolysis can affect pool pH through the creation of H202 and OH radicals.2. Radiolysis can break down electrical cable insulation or dissolved nitrogen to form strongacids.As discussed in the March 2011 report, the formation of H202 and OH radicals is not considered tobe a significant issue based on previous analyses. The formation of strong acids due to thebreakdown of cable insulation or dissolved nitrogen may have a non-negligible impact on the long-Page 8 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013term pH, and therefore should be considered. As discussed in the March 2011 report, one licenseedetermined that acid formation would reduce the pH by 0.2.CCNPP Resolution PlanA design calculation exists [Error! Reference source not found.] that computes the amount of acidthat could be formed long-term at CCNPP. The quantity of acid determined in this calculation willbe included in the chemical effects tests.2.2 Radiological Effects: Corrosion Rate ChangesNRC IndustryPosition PositionRadiolysis of water bearing the chloride ion (Cl) can elevate the post-LOCA corrosion rate throughformation of hypochlorite (CIO-) or hypochlorous acid (HOG). The presence of these acids couldincrease the corrosion rate of metallic and nonmetallic species in containment, which in turn couldalter the chemical byproducts formed. Hence, the chemical precipitates that form could differ fromthose previously evaluated. These different precipitates could subsequently affect ECCS performancein a manner that has not been considered previously.The following root issue is contained in this item:1. Radiolysis of water with chloride ions can create strong acids.Chloride ions may be in solution primarily due to the breakdown of electrical cable insulation, butalso due to potential leaching from coatings. As discussed for Item 2.1, the formation of strongacids may have a non-negligible impact on long-term pH, and therefore will be considered.CCNPP Resolution PlanThe addition of acid to the tests to simulate radiolysis is addressed in Item 2.1.Page 9 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20132.3 HydrolysisNRC IndustryPosition Position I XNickel oxide (NiO), as well as other oxides, resulting from the corrosion of stainless steel and Alloy 600metals can become a catalyst for producing H2 from radiolysis of water. This process occurs morereadily at higher water temperatures (i.e., hydrothermal environments). The hydrothermal hydrolysisof various organic/inorganic coating and insulation materials could partially depolymerize polymericmaterials, producing materials ranging from small molecules to colloids. The colloids couldsubsequently aggregate into larger particles and gels. If this were to occur, the aggregateddepolymerized materials may be more likely to transport to the sump strainer and affect pumpperformance or create chemical precipitates with different characteristics than those evaluated.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 watermolecules to split into hydrogen and hydroxide ions. Hydrolysis is more significant at highertemperatures (generally above boiling). Since the containment pool temperature would only beabove 200'F for a few hours, and the formation of H2 due to hydrolysis is a gradual process, this isan insignificant issue.CCNPP Resolution PlanNo action required.2.4 Conversion of N2 to HNO3NRC industryPosition U Position IwOne panelist was concerned about the effects of nitric acid (HNO3) formed in the containment pool dueto radiolysis of dissolved nitrogen (N2). This panelist was mostly concerned that the HN03concentration may overwhelm the buffering capacity and cause the containment pool pH to dropprecipitously to a range within 1-3. If the containment pool pH were this acidic, the redox potentialbecomes strongly oxidizing and corrosive and would lead to significant metallic corrosion andleaching of inorganic ions from other materials (e.g., concrete). Most previous NRC and industry-Page 10 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013sponsored research has evaluated the chemical effects and their implications associated within theneutral-to-alkaline pH range (i.e., 7-10) that is expected within the buffered post-LOCA containmentpool. Therefore, if the containment pool pH were highly acidic (i.e., 1-3), the chemical effects thatwould occur may differ significantly from those previously evaluated. The implications of these effectson ECCS performance would also be largely unknown.The following root issues are contained in this item:1. Radiolysis of dissolved N2 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 tobe relatively low due to the low solubility of N2 in water. The assumption that the pool couldbecome strongly acidic did not take into account the presence of the buffers. Therefore, the pool isnot expected to become strongly acidic. However, similar to the other issues regarding theformation of strong acids, the effects on long-term pH due to the formation of nitric acid should beconsidered.CCNPP Resolution PlanThe addition of acid to the tests to simulate radiolysis is addressed in Item 2.1.2.5 Additional Debris Bed Chemical ReactionsNRC I Industry IPosition PositionThe concentration of radionuclides, postulated to be hundreds of Curies, available within the sumpstrainer fiber bed acts as a "resin bed" or chemical reactor potentially altering the local chemicalconditions, such as pH. A number of possible radiolytic reactions could occur which may directly alterthe chemical byproducts formed. This effect may lead to the formation of different, or a largerquantity of, chemical products than those evaluated, which could have a different impact on head lossthan that considered.The following root issues are contained in this item:1. Radionuclides trapped in the debris bed may change the local chemistry and causeprecipitation.2. Radionuclides trapped in the debris bed may cause the bed to break down.Page 11 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013As discussed in the March 2011 report, local changes in the chemistry (i.e. the formation of H202due to radiolysis) will not have a significant effect since the constant flow through the debris bedwill effectively flush it out. Also, the concern that the fiber bed may break down due to theradionuclides is not considered to be significant since materials similar to fiberglass insulation areroutinely used as a filtration media for high activity particulate.During the chemical effects summit, the NRC questioned whether other types of insulation orcoatings 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 theECCS is successful, the concentration of radionuclides in the sump will be small. However, ifkey accident sequences in the PRA lead to core damage, the potential effects of large quantitiesof radionuclides in the sump may need to be considered.CCNPP Resolution PlanThe 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 highradiation. Radiation would not have any effect on the stainless steel RMI or the mineral wooldebris. The marinite debris quantity at CCNPP is minor compared to the quantity of fiberglassdebris. Therefore, even if radiolysis did have an effect on marinite particulate, it would notsignificantly change the structure of the overall debris bed at CCNPP. Unqualified coatings maypossibly 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 thatresult in core damage. If the percentage of these events is significant, the chemical effects ofradiation degradation of unqualified coatings will be investigated. If the percentage of these eventsis insignificant, no additional evaluation is required as the radiation levels during non-core damageevents is not expected to be high.3.0 PHYSICAL, CHEMICAL, AND BIOLOGICAL DEBRIS SOURCE TERMS3.1 Crud ReleaseNRC Industry vPosition PositionA PIRT panelist postulated that iron and nickel corrosion oxides up to 125 microns thick may exist onthe interior of the RCS piping, fuel, and components. These oxides could be released by the hydraulicPage 12 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013shock of the LOCA event. After release, the reduced Fe and Ni ions can be dissolved in the RCS (aidedby radiolysis) and, when combined with air, can form oxides of hematite, maghemite, and magnetite.The crud release can create a localized radiolytic environment on materials caught on the sumpscreens, which could affect subsequent chemical reactions. The crud particles would also add to thedebris 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 of crud could be released as another source of particulate debris.As discussed in the March 2011 report, the radiolytic effects of crud are insignificant compared toother sources. The March 2011 report estimated that the total quantity of crud in the RCS could beon the order of 400 kg. This is a potentially significant source of particulate debris, but it is notlikely that 100% of the crud would be released by the thermal and hydraulic shock of a LOCA. TheMarch 2011 report concluded based on transport considerations that this is not a significant issue.At the chemical effects summit, the NRC questioned whether the RCS crud could transport and havea significant impact on head loss.STP performed an evaluation of crud release due to the thermal and hydraulic shock of a LOCA anddetermined the quantity of crud released would be on the order of 25 lbs which is less than theassumed latent debris particulate load.CCNPP Resolution PlanThis item will not be addressed in the chemical effects tests. The crud is a source term forparticulate debris and is not expected to affect the chemical environment.3.2 Jet ImpingementNRC IndustryPosition X IPosition XThe two-phase jet, and fine debris within the jet, will impact surfaces and could chip coatings, causemetallic erosion, or ablate materials like concrete. This phenomenon will govern the contributions ofthese 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 of normallypassivated materials like stainless steel. Most of the discussion from the peer review panel describesPage 13 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013the jet interaction with materials as the primary source for post-LOCA debris. Jet impingement couldresult 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 lossand chemical effects is an important issue that should be considered.As discussed in the March 2011 report, jet impingement during blowdown has a very shortduration, and any pitting that occurs would be localized and have a minimal effect on the overallquantity of corrosion products. Also, CCNPP-specific evaluations account for jet interactions withcoatings and other containment materials, such as thermal insulation and fire barriers. The amountof material released from metallic erosion, concrete ablation, or metallic pitting induced by jetimpingement will be insignificant compared to the CCNPP design basis debris load used for strainerqualification.CCNPP Resolution PlanThe issue of jet impingement need not be addressed in the CCNPP chemical effects testing andanalysis.3.3 Debris Mix Particulate/Fiber RatioNRC -S40 Iindustry -Position PositionI UBreaks in different locations will create different debris characteristics with respect to the total massof debris, debris constituents, and the ratio of particulates to fiber. Depending on the specific breaklocation, significantly different types and quantities of debris (e.g., Cal-Sil and fiberglass insulations)can alter the type and quantity of chemical effects. Ultimately, the debris bed characteristicsdetermine the chemical product capture efficiency and the total pressure drop across the sump screenstrainer.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.Page .14 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013In an integrated environment, the presence of some materials may inhibit the corrosion ordissolution of other materials. For example, silicon that is released into solution from thedissolution of fiberglass may inhibit the corrosion of aluminum. In some cases, therefore, scenarioswith lower quantities of certain types of debris could potentially result in more severe chemicaleffects.Fiber beds act as very effective filters and can capture small particles. As the particulate to fiberratio increases, the debris bed is compacted and the filtration efficiency increases (along with thehead loss). Therefore, the particulate to fiber ratio is a significant parameter.CCNPP Resolution PlanThe mixture of debris to be used in the tests is addressed in Item 1.1. The long-term tests willuse a special debris bed with a pre-defined ratio of particles to fibers that will be used as a headloss detection instrument to assess the relative impact of chemical effects under a standardizedcondition.3.4 Effects of Dissolved Silica from RCS and RWTNRC -" Industry -Position W PositionDissolved silica is present in the water storage systems and the RCS during normal operation. Thissilica can react with other chemical constituents (most prominently magnesium, calcium, andaluminum) that form as a result of material dissolution or corrosion, or both, within the containmentpool after the LOCA occurs. This reaction may result in a greater concentration of the chemicalprecipitates than would otherwise exist. The reaction may also alter the nature of the chemicalprecipitates by creating amorphous materials or gels or precipitates with retrograde solubility (i.e.,they become more insoluble as temperature increases). The creation of additional chemicalprecipitates, amorphous materials, and retrograde soluble species could degrade ECCS performanceby increasing head loss at the sump strainer or decreasing in the heat transfer rate from the reactorfuel if significant quantities of silica-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 theevent.Page 15 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013Silicon is an important factor for chemical effects. In some cases, it may help inhibit corrosion ofaluminum, and also can contribute to precipitate formation. Therefore, the initial concentration ofdissolved silica in the RCS, RWST, and accumulators should be considered.CCNPP Resolution PlanThe quantity of silica present in the RCS, RWST, and accumulators at CCNPP will be evaluatedalong with the boron and lithium as described in Item 1.1, and the contribution of silica fromeach source during each test will be calculated and added at the beginning of the test asdescribed for boron and lithium in Item 1.13.5 Containment Spray TransportNRC IndustryPosition W 16 Position w 16Following 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 containmentdebris sources (types, amounts, compositions) and chemical species reaching the containment poolenvironment which could affect the sump strainer debris bed and the formation of chemicalprecipitates.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 PlanCCNPP prepared conservative debris generation and transport calculations that specificallyaddressed latent debris, corrosion products, insulation materials, and coating debris. Theresults of the conservative debris generation and transport calculations will be addressed inthe CCNPP chemical effects testing and analysis. Also, the corrosion of materials exposed tocontainment spray above the pool will be accounted for in the chemical effects tests.Page 16 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20133.6 Initial Debris DissolutionNRC ndustry -Position PositionTypical debris generated by the LOCA (within the first 20 minutes) includes Cal-Sil insulation, cementdust, organic fiberglass binders, and protective coatings. Initial debris dissolution could indicatepotential important contributors to the chemical containment pool environment. It is possible that thedissolved, ionic species could react and precipitate to form new, solid phases that were not originallyin the containment pool.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 effectstests.CCNPP Resolution PlanThe relevant materials and debris determined to be present at CCNPP and contribute tochemical effects will be included in the test loop at the beginning of each test. Determination ofthe quantities of debris is addressed in Item 1.1.3.7 Submerged Source Terms: Lead ShieldingNRC -Industry -Position I PositionAcetates present in the containment pool will corrode any submerged lead existing in containment,which could lead to formation of lead carbonate particulate or dissolved lead within the containmentpool. Lead blanketing or lead wool is used to shield radiation hot spots during refueling outages andmay remain in the containment building during the fuel cycle. In addition, several plants may still usesmall quantities of lead wool for insulation.Lead carbonate contributions would provide additional particulate loading within the containmentpool that could contribute to head loss at the sump strainer screen. Dissolved lead could also lead tocracking of submerged stainless steel structural components within containment. Neither the testingconducted to date nor do the licensee evaluations of ECCS performance consider these contributions.Page 17 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013These omissions are potentially non-conservative if significant quantities of lead carbonate ordissolved 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, thedissolution of lead and subsequent precipitation is a potentially significant issue that should beconsidered.As discussed in the March 2011 report, relatively low lead concentrations will not induce crackingin stainless steel components within the 30-day mission time.CCNPP Resolution PlanAn evaluation of the sources of lead in containment at CCNPP will be performed to determinewhether there is a potential for significant lead quantities to be released into solution. If so, itmay be necessary to include lead in the chemical effects tests. Determination of the quantity oflead debris is addressed in Item 1.1.3.8 Submerged Source Terms: CopperNRC ] IndustryPosition Position I 1Copper present in containment can accelerate or inhibit corrosion of other metals. One way in whichCu can alter the corrosion rate of other materials is by forming a galvanic couple. Galvanic effects canaccelerate corrosion of less noble material while inhibiting corrosion of more noble materials.Dissolved copper can also enhance the rate of corrosion of other metals within an oxygenatedenvironment. Different corrosion rates can impact the amount of corrosion products formed andtherefore 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 galvaniccells.3. Copper can inhibit corrosion of other metals by depositing and creating a passivation layer.Page 18 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013As discussed in the March 2011 report, the potential effect of galvanic couples in containment isinsignificant. Local galvanic cells may enhance corrosion of aluminum, but this would only apply tothe submerged aluminum. Also, as discussed in the March 2011 report, copper deposits wereobserved on aluminum samples in some of the ICET tests, which may have helped inhibit aluminumcorrosion since the tests had negligible aluminum concentrations. Copper corrosion is expected tobe 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 chemicaleffects-potential enhancement of metal corrosion due to a local galvanic cell. The NRC also statedthat the corrosion of zinc (from galvanized steel or other sources), and subsequent formation ofzinc precipitates is a potentially significant issue that should be evaluated.CCNPP Resolution PlanAn evaluation of the sources of copper and zinc in containment at CCNPP will be performed todetermine whether there is a potential for significant quantities of these metals to be releasedinto solution. If so, it may be necessary to include copper and/or zinc in the chemical effectstests. Determination of the quantity of copper and zinc is addressed in Item 1.1.3.9 Concrete Material AgingNRC I IndustryPosition PositionThe PIRT panelists raised questions about the effect of aging on the leaching process for nonmetallicmaterials such as concrete. Neither the exposed concrete faces nor concrete dust in the containmentbuilding is likely to be fresh. After 30years of exposure to the atmosphere, a substantial fraction ofboth the exposed calcium silicate hydrate (C-S-H) gel and the portlandite (Ca(OH)2) constituents of theconcrete would have been carbonated. Carbonation or other aging processes of concrete could affectthe leaching rates and dissolved species as compared to relatively fresh concrete samples used in theICET experiments and other research programs.The following root issue is contained in this item:1. Aged concrete may release a larger quantity of calcium.Concrete surfaces in containment are generally coated, which would prevent carbonation due toaging. However, this may be a significant issue for plants with large uncoated concrete surfaces;Page 19 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013especially if the plant uses a TSP buffer. CCNPP has little uncoated concrete and does not use TSPas the buffer.During the chemical effects summit, the NRC stated that the difference in dissolution between agedand fresh concrete is not significant and it is not necessary to use aged samples for chemical effectstesting.CCNPP Resolution PlanNo action required.3.10 Alloying EffectsNRC IndustryPosition PositionAnother issue raised by the PIRT is the effect of different alloys on the quantity of corrosion products.Corrosion rate data exhibit wide variability depending on the specific corrosion conditions and thenature of the 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 thanpure metals. In realistic testing, it may be beneficial to use the actual alloys that exist incontainment. Regardless, it is important to appropriately justify all surrogate materials (includingmetal coupons) that are used in chemical effects tests.At the chemical effects summit, the NRC stated that there is not a large difference betweencorrosion rates for pure materials and alloys. However, it is appropriate to use materials that arerepresentative of what is in containment.CCNPP Resolution PlanAppropriate surrogate materials will need to be selected for the chemical effects tests.Page 20 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20133.11 Advanced Metallic Corrosion UnderstandingNRC Industry -'Position PositionThe PIRT panel raised several other issues related to the understanding of metallic corrosion in thepost-LOCA environment. These issues include enhanced Al corrosion caused by hypochlorite or othercatalytic 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 onECCS sump head loss.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 importantfactor that should be considered. Also as discussed previously, pitting from jet impingement isconsidered to be an insignificant factor due to the localized impact of the jet. Generally, synergisticeffects tend to inhibit corrosion, but both synergistic effects and corrosion inhibition are inherentlyconsidered in integrated testing.CCNPP Resolution PlanAppropriate synergistic effects and corrosion inhibition are addressed due to the selection ofmaterials in the proper proportions relative to the CCNPP containment, as described in Item1.1. Acid formation is addressed in Item 2.13.12 Submerged Source Terms: Biological Growth in Debris BedsNRC Industry vPosition I PositionThe PIRT considered the propensity for bacteria or other biota to grow in preexisting debris bedslocated on the sump strainer screen or elsewhere within the ECCS system. Significant bacterial growthmay be important if it creates additional debris that contributes to sump screen clogging ordetrimental performance of downstream components like pumps and valves.Page 21 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013The 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 hightemperature, low or no light, and high radiation conditions. Any microorganisms that do survivewould 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 radiationprotection individuals at CCNPP has inspected containment sumps at multiple plants and cleanedtwo of them. In none of these cases was biologic growth observed.CCNPP Resolution PlanThis item will not be addressed in chemical effects tests.3.13 Reactor Core: Fuel Deposition SpallNRC Industry IPosition ] PositionSpall of reactor fuel cladding oxides (ZrO2) and deposited chemical products could be a potentialsource of activated materials that could affect chemical reactions in the post-LOCA containment pool.Also, precipitates of post-LOCA chemical products (organics, Al, B, Ni, Fe, Zn, Ca, Mg, silicates (SiO3-and Si044-), and C032-based products) could deposit on the fuel clad and spall, contributing either toclogging 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 containmentpool.2. Precipitation and spall of chemical products on the fuel could contribute to fuel or strainerclogging.As discussed previously, the effect of activated particles on chemical effects due to radiolysis isconsidered to be insignificant. However, this debris could contribute to the source term forparticulate debris with an effect on the overall head loss across the strainer or fuel channels. Thisissue is addressed in Item 3.1.Page 22 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013Some precipitates, particularly certain calcium precipitates, exhibit retrograde solubility. As waterflows through the reactor vessel, the high temperature in the vicinity of the fuel rods may causesome of these materials to precipitate. The precipitates may form on the fuel rods themselves, or insolution where they can be swept out of the reactor vessel and potentially contribute to strainerclogging. This is a potentially significant issue that needs to be addressed for materials that exhibitretrograde solubility.CCNPP Resolution PlanThe effects of chemical precipitation on the fuel rods have been previously addressed in aconservative manner for CCNPP using the LOCADM software. Precipitation of materials withretrograde solubility in the bulk solution within the reactor core will be addressed in bench-scale tests based on the concentration, core temperature, and solubility limit for potentialprecipitates.4.0 SOLID SPECIES PRECIPITATION4.1 PolymerizationNRC Industry vPosition PositionThe PIRT panelists expect polymerization to occur after molecular precipitation as a precursor to solidspecies agglomeration in post-LOCA environments. Molecular precipitation refers to the formation ofbonds between metallic species and oxygen to form monomers. Polymerization is the ripening of thesebonds to form covalent bonds and the growth of the monomers through one of many types ofpolymerization reactions. Chain polymerization, which is the most common, consists of initiation andpropagation reactions and may include termination and chain transfer reactions. Step-growth andcondensation polymerization are two additional mechanisms. Polymerization occurs untilapproximately nanometer-sized particles have formed. These particles can then continue to grow tolarger sizes through agglomeration mechanisms.The PIRT panelists expect polymerization is needed to form large enough particles to tangibly affectECCS 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 onlyif the differences in polymerization mechanisms in the simulated and actual post-LOCA environmentsare significant enough to alter head loss or downstream effects associated with the chemicalprecipitates.Page 23 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013The 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 inthe formation of precipitates, but is appropriately represented in testing and does not need to befurther evaluated.CCNPP Resolution PlanNo action required.4.2 Heat Exchanger: Solid Species FormationNRC I industryPosition U Position IChemical species having normal solubility profiles may be dissolved in the containment pool at highertemperatures. However, these chemical species may precipitate in the heat exchanger because of adrop in temperature of approximately 30 degrees F. Some possible solid species that could forminclude Al(OH)3, FeOOH, and amorphous SiO2.The lower temperature at the heat exchanger outletcould alsofacilitate the development of macroscale coatings or suspended particulates, or both, thatcan continue to transport in the circulating fluid. Possible implications of this 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) speciesremain insoluble at higher containment pool temperatures and cause additional head loss uponrecirculation, 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 tocause 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, thetemperature drop across the heat exchangers may be significantly higher than 30°F. Since it takestime for containment materials to corrode and dissolve, precipitation may not be possible untilmuch 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 thePage 24 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013duration that coolant flow is exposed to lower temperatures downstream of the heat exchangers isrelatively brief.CCNPP Resolution PlanThe final portion of the tests will be used to investigate low temperature chemical effects byreducing the temperature in stages until room temperature is achieved.4.3 Reactor Core: PrecipitationNRC -ý industryPosition Position WThe increased temperature in the reactor vessel (i.e., 70 degrees C higher than the containment pool)and retrograde solubility of some species (e.g., Ca silicate, Ca carbonate, zeolite, sodium calciumaluminate) causes precipitation and additional chemical product formation. This could result in thefollowing: (1) additional precipitate could be created and transported to the sump screen that wouldthen contribute to head loss and (2) precipitate or spall (see Section 3.13 of this report) passingthrough the sump screen may degrade the performance of ECCS components downstream from thescreen.The following root issue is contained in this item:1. High localized temperatures in the reactor vessel may cause precipitation of materials withretrograde solubility.This is a potentially significant issue that should be evaluated in chemical effects testing. It shouldbe 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 (i.e.next to the fuel cladding) to be significantly hotter than the pool, which could result in localizedprecipitation. Also, under certain scenarios (such as a cold leg break during cold leg injection), it ispossible for the water in the core to boil. Even under these conditions, however, the maximum bulktemperature in the core would be limited to the saturation temperature, which would neverapproach a level that is 158°F hotter than the pool. Therefore, the focus of this issue should be onlocalized high temperatures in the reactor vessel rather than overall high temperatures in the bulkflow.Page 25 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013CCNPP Resolution PlanAn investigation of existing literature will be performed to evaluate the possible effects ofretrograde solubility, and thermodynamic software may be used to identify possible speciesthat may exhibit retrograde solubility. In addition, this item may be explored in bench-scaletesting.4.4 Particulate Nucleation SitesNRC V Industry vPosition PositionParticles within containment create the nucleation sites required for chemical precipitation.Examples of particles that could serve as nucleation sites include irradiated particles, dirt particles,coating debris, insulation debris, biological debris, and other materials within the post-LOCAcontainment pool. These particles then grow through polymerization (see Section 4.1 of this report)and agglomeration (see Sections 5.1 and 6.2 of this report) into solid species that are large enough topossibly degrade ECCS performance.This issue identifies a fundamental aspect of the formation of solid species. Implications only arise ifthe nucleation sites in the post-LOCA environment are not appropriately simulated in testing. That is,the quantities and types of nucleation sites used in testing should be representative of the post-LOCAenvironment 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 numerousnucleation sites. Therefore, this is not a significant issue.CCNPP Resolution PlanNo action required.Page 26 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20134.5 CoprecipitationNRC IndustryPosition PositionCoprecipitation occurs when a normally soluble ion becomes either included or occluded into thecrystalline structure of a particle of insoluble material. Precipitation of one species could lead toincreased precipitation of another species (which, if taken separately, are each below their solubilitylimit). Thus, more solid species could form, which could lead to a greater concentration of chemicalprecipitates at the sump strainers or downstream of the strainers. Additionally, the species that formcould differ in size from those observed in the ICET tests (i.e., 1 to 100 microns) such that they affectthe head loss at the sump strainer more significantly.The following root issue is contained in this item:1. Precipitation of one material may result in precipitation of another material that would nototherwise have precipitated.Coprecipitation does not reduce the solubility limit of precipitates, and therefore would not causeprecipitation 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 reactivematerials are present together and coprecipitation can occur naturally. Therefore, this issue isinherently included in an integrated test.CCNPP Resolution PlanThe issue of coprecipitation is addressed by inclusion of all materials that participate inchemical reactions in the same proportions that they are present at CCNPP, as described inItem 1.1.5.0 AGGLOMERATION AND SETTLING: CHEMICAL EFFECTS5.1 Inorganic AgglomerationNRC -~ IndustryPosition Position xInorganic agglomeration is the formation of larger clumps of smaller particulates. This phenomenondepends upon the pH of the point of zero charge (PZC) of the species and the ionic strength (the higherthe ionic strength, the smaller the distance for agglomeration) of the fluid. This phenomenon isPage 27 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013Given their small size, chemical precipitates can readily transport under relatively low flowconditions, and it is not expected that significant settling would occur. Therefore, this is notconsidered to be a significant issue.CCNPP Resolution PlanNo action required.5.3 Quiescent Settling of PrecipitateNRC IndustryPosition PositionQuiescent flow regions within the containment pool promote settling. The low flow rate within most ofthe containment pool also allows larger size, more stable particles and precipitates to form, whichpromotes settling. Settling of nonchemical debris and precipitate could be beneficial with respect tothe 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 containmentpool.As discussed above, this is not considered to be a significant issue.CCNPP Resolution PlanNo action required.5.4 Transport Phenomena: Precipitation and CoprecipitationNRC IndustryPosition PositionPrecipitation or coprecipitation and ripening of solid species within the containment pool wouldcreate solid species which are less likely to transport. Decreased transportability will result in lessproduct 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.Page 29 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013sensitive to many factors, including particle shape factors, and maximum particle size. Inorganicagglomeration of small 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 particulatemay 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 inNUREG/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 chemicalprecipitates is not a significant issue.CCNPP Resolution PlanNo attempt to either stimulate or prevent agglomeration of particles will be incorporated intothe chemical effects tests. In the chemical effects tests, particulate debris will be pre-depositedin the debris beds and will not be circulating in the solution in significant quantities. Thesolution chemistry in the chemical effects tests will be similar to the CCNPP system, so theformation and behavior of chemical precipitates will be similar, with particulate debris alreadypresent in the debris bed.5.2 Deposition and SettlingNRC I industryPosition PositionChemical products formed in the post-LOCA containment environment could either settle within thecontainment pool or be deposited on other surfaces. Chemical species which attach to or coatparticulate debris may enhance settling. Examples are aluminum coating on NUKON fiber shiftingthe PZC or formation of a hydrophobic organic coating. This could result in less particulate debris andchemical product transporting to the sump screen and either accumulating on or passing through it.The possible implications of this issue are that the chemical precipitates added to the plant-specificchemical effects tests could result in increased settling during the tests compared to actual plantconditions.The following root issue is contained in this item:1. Chemical precipitates may settle or enhance settling of other particulate in the containmentpool.Page 28 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013As discussed above, this is not considered to be a significant issue.CCNPP Resolution PlanNo action required.6.0 ORGANICS AND COATINGS6.1 Break Proximity to Organic SourcesNRC IndustryPosition X Position XThe pipe break location plays an important role in debris generation. If the break occurs in closeproximity to organic sources, it could introduce a significant amount of organic materials into thecontainment pool. Organic sources could then affect the nature, properties, and quantities of chemicalbyproducts that form in the post-LOCA containment environment. The scenario evaluated by the PIRTconsidered failure or leakage of oil and other organics from either the RCP oil collection tanks or lubeoil systems resulting from LOCA-induced damage. If the pipe break occurs in close proximity to theorganic sources, up to approximately 250 gallons of oil may be released to the containment pool. Ifthis 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 containmentpool.2. Other organic materials may be present due to failure of coatings and the organic binders ininsulation debris.As discussed in the March 2011 report, one licensee added a large quantity of oil (representative ofthe quantity from one RCP motor) to an integrated chemical effects head loss test. The oil additionhad no impact on the head loss, and is not considered to be a significant factor.Similarly, the presence of smaller quantities of organic material from other sources is not expectedto have a significant effect on the pool chemistry conditions.Page 30 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013CCNPP Resolution PlanThe cases where a significant quantity of oil would be introduced to the containment poolwould be limited to a few larger breaks in the vicinity of one of the RCP motors. Since themajority of break cases would not have significant quantities of oil, oil will not be included inthe 30-day chemical effects tests. The issue of organic materials from coatings failure andorganic binders in insulation debris is addressed in Item 6.4, below.6.2 Organic AgglomerationNRC -~ IndustryPosition PositionOrganic agglomeration is the process of small organic colloidal particles (1 to 100 nanometers in size)joining together, or coagulating, to form larger particles and precipitates. Coagulated particles cancollect on sump strainers, decreasing ECCS flow; they could also collect on other wetted surfaces, suchas walls or structural steel, and decrease the debris loading on the sump screen. Hence, head lossesand 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 adebris 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 PlanThe resolution of this item is the same as Item 5.1.6.3 Organic ComplexationNRC industryPosition X PositionOrganic complexing agents act to inhibit agglomeration either by adsorption onto solid surfaces or byinteraction in solution with metal ions. Organic surface complexation occurs if organic molecules (i.e.,amines, acids, and heterocycles) adsorb on surfaces of ions or solids and inhibit the subsequentPage 31 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013precipitation or growth of those species. The implications of organic complexation are counter tothose associated with organic agglomeration. Organic complexation could reduce the effectsassociated with chemical precipitates and therefore may be beneficial to ECCS performance if thisphenomenon is not credited or addressed during plant-specific testing.The following root issue is contained in this item:1. Organic complexation may inhibit agglomeration.Since both inorganic and organic agglomeration are not considered to be significant issues, organiccomplexation would be an insignificant factor also.CCNPP Resolution PlanNo action required.6.4 Coating Dissolution and LeachingNRC Iindustry -Position Position I _VCoatings existing within containment represent possible additional physical debris sources. Generallyconservative guidancefor considering the effects of physical coating debris is provided for theevaluation of ECCS performance. However, dissolution and leaching of coatings can impact thechemical effects that occur within, or are transported to, the ECCS cooling water. Both inorganic (e.g.,zinc-based) and organic (e.g., epoxy-based) coatings exist within containment. One concern is thatthese coatings leach chemicals as a result of being submerged in the containment pool environmentafter the LOCA. Coatings may create additional chemical species (e.g., chlorides or organics) withinthe containment pool that could potentially increase sump screen head loss or promote moredeleterious 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 fromcoatings is expected to be relatively low. However, this is a potentially significant issue and shouldbe appropriately addressed in realistic testing.Page 32 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013CCNPP Resolution PlanExisting literature will be reviewed to assess the rates of leaching from coated surfaces. Ifnecessary, information from literature can be supplemented with data from bench-scaletesting. If the literature or bench-scale testing indicates that leaching from coatings can affectthe overall pool chemistry, appropriate materials will be included in the chemical effects tests.7.0 CHEMICAL EFFECTS ON DOWNSTREAM SYSTEM PERFORMANCE: PUMPS, HEATEXCHANGERS, AND REACTOR CORE7.1 Emergency Core Cooling System Pump: Seal Abrasion and Erosion or CorrosionNRC IndustryPosition PositionAbrasive wearing of pump seals (e.g., magnetite-high volume or concentration of mild abrasive)creates additional materials that contribute to containment pool chemistry. In addition, chemicalbyproducts cause erosion or corrosion of pump internals, especially close-clearance components (e.g.,bearings, wear rings, impellers). The possible implications of these phenomena are (1) additionalparticles could contribute to reactor core clogging, (2) particles could add additional sump screenloading, (3) particles could affect chemical species formation, and (4) pump performance degrades,possibly to the point of being inoperable.The following root issue is contained in this item:1. Particulate debris generated by abrasive wearing of pump seals may cause additionaldownstream problems.As discussed in the March 2011 report, the quantity of particulate material generated by wearing ofthe pump seals is insignificant compared to other particulate sources. Also, the pump materials arenot unique, and the surface area of similar metals and materials in containment are large enoughthat the impact of the pump internals on chemical effects is considered to be negligible. Therefore,this issue is insignificant.CCNPP Resolution PlanNo action required.Page 33 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20137.2 Heat Exchanger: Deposition and CloggingNRC IndustryPosition PositionSolid species which form in the heat exchanger lead to surface deposition or clogging, or both, withinclose-packed heat exchanger tubes (5/8-inch in diameter). This could cause decreased flow throughthe heat exchanger core or diminished heat transfer between the ECCS and heat exchanger coolingwater, or both. Diminished cooling of the ECCS water could ultimately decrease the capacity of theECCS water to remove heat from the reactor core.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 shearstrength to block flow through the heat exchanger tubes. It's possible that some precipitates couldcreate a thin coat on the tube walls. However, since the precipitates would generally form later inthe event when the heat exchangers have ample margin, any slight degradation in performance dueto the precipitates is negligible.CCNPP Resolution PlanThe efficiency of heat exchange and performance of the heat exchangers will not be monitoredduring the chemical effects tests. However, if the heat exchanger used in the test can bedisassembled, the heat exchanger tubes will be visually inspected for the presence ofprecipitates or scale formation, and if precipitates or scale is present, a sample of theprecipitates will be scraped from the surfaces and analyzed using the techniques used forprecipitate analysis.7.3 Reactor Core: Fuel Deposition and PrecipitationNRC IndustryPosition We PositionI % IThe increased temperature (+70 degrees Cfrom containment pool) and retrograde solubility of somespecies (e.g., Ca silicate, Ca carbonate, zeolite, sodium calcium aluminate) causes scale buildup on thereactor core. Zn, Ca, Mg, and C02-based deposits, films, and precipitates mayform at highertemperatures within the reactor core. This may lead to (1) a decrease in heat transfer from thePage 34 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013reactor fuel, (2) localized boiling due to insufficient heat removal, and (3) spallation of deposits,creating additional debris sources which could clog the reactor core or contribute to sump screen headloss.The following root issue is contained in this item:1. High localized temperatures in the reactor vessel may cause precipitation of materials withretrograde solubility.As discussed previously, precipitation of materials with retrograde solubility on the fuel surfaces orin solution within the core is a significant issue that needs to be addressed.CCNPP Resolution PlanThe resolution for this item is the same as the resolution for Item 3.13 and Item 4.3.7.4 Reactor Core: Diminished Heat TransferNRC IndustryPosition IX IPosition XPhysical and chemical solid debris within the ECCS coolant water could diminish the fluid's heattransfer capacity and degrade the ability of the coolant to remove heat from 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 leginjection since the water entering the core would boil off raising the concentration of boron, otherdissolved materials, and suspended solids. As discussed in the March 2011 report, the relativelydilute concentration of dissolved solids would not significantly affect the rate of boiling and rate ofheat 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 becompleted by 2015. Although the outcome of the PWROG research may change the acceptable limitfor boron concentration in the reactor vessel, it would not affect the physical processes that mustbe evaluated in realistic chemical effects testing. Therefore, the PWROG progress should bemonitored for potential plant modifications that may be required (i.e. timing for switchover fromcold leg to hot leg injection), but is not a significant issue for realistic chemical effects testing.Page 35 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 2013At the chemical effects summit, the NRC announced that the boron precipitation issue must now beaddressed as part of the overall resolution of GSI-191.CCNPP Resolution PlanThe resolution of the boron precipitation issue will not be addressed in the CCNPP chemicaleffects test program. This issue will be addressed as part of the overall resolution of GSI-191 atCCNPP.7.5 Reactor Core: Blocking of Flow PassagesNRC Iindustryosition PositionI XFuel deposition products and precipitated retrograde soluble chemical species spall and settle withinthe reactor vessel. Settling can be potentially deleterious ifflow passages to the fuel elements areeither globally or locally impeded. Reduced flow within the RPV, if significant, has the potential todiminish 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 reactorvessel must be properly addressed. This item raises an additional issue of the potential settling ofprecipitates or other debris spall under low flow conditions within the reactor vessel. During coldleg injection, the flow would move upward through the core and would tend to lift the debris andtransport it out of the reactor vessel. If the settling velocity is high enough for the debris to settle, itwould not be expected to create any significant head loss since the flow would simply have toovercome the "weight" of the debris to continue injecting into the core. During hot leg injection, theflow would move downward through the core in the same direction that settling debris would bemoving. The debris could accumulate in various locations where it could form a bed and causehigher head losses. However, this issue would occur regardless of debris settling. Therefore, debrissettling concerns are insignificant for realistic chemical effects testing.CCNPP Resolution PlanNo action required.Page 36 of 37 Chemical Effects PIRT Considerationsfor Calvert Cliffs Nuclear Power PlantCCNPP-CHLE-003Revision Ob, January 24, 20137.6 Reactor Core: Particulate SettlingNRC I IndustryPosition PositionRelatively low, upwards flow (for cold leg injection) within the reactor causes particulates to settle.Compacted deposits form and may impede heat transfer and water flow, especially for lower portionsof reactor fuel.The following root issue is contained in this item:1. Particulate debris may settle during cold leg injection causing flow path blockage orinhibiting heat transfer.As discussed previously, debris that settles during cold leg injection would not result in significanthead loss. Also, as discussed in the March 2011 report, the higher flow through the core for a hotleg break, and the turbulence due to boiling for a cold leg break would be expected to keep theparticulate debris from blocking heat transfer to the lower portions of the fuel. Therefore, debrissettling concerns are insignificant for realistic chemical effects testing.CCNPP Resolution PlanNo action required.Page 37 of 37