ML16056A412

GSI-191 Resolution Plan: Follow-Up on Chemical Effects

ML16056A412
Person / Time
Site:	Vogtle
Issue date:	03/02/2016
From:	Southern Co, Southern Nuclear Company
To:	Office of Nuclear Reactor Regulation
Koenick S
References
GSI-191
Download: ML16056A412 (22)

Text

VOGTLE GSI-191 RESOLUTION PLAN: FOLLOW-UP ON CHEMICAL EFFECTS MARCH 2, 2016

PURPOSE OF MEETING

• Address topics on chemical effects from the November 5th, 2015 meeting

• Clarify pH Values used for Release and Solubility

• Discuss Calcium Release Rate vs. pH

• Detail Implementation of the Howe et al. (UNM) Aluminum Corrosion Equations

• Summarize Use of WCAP-17788 Testing with the ANL Equations to Support Short Term Aluminum Solubility 2

CONTAINMENT SPRAY AND POOL pH (NOVEMBER 5, 2015 MEETING, UPDATES/CHANGES IN RED)

Combining conditions in a non-physical way to bound release and precipitation

• Containment spray from the RWST will use a maximum pH (5.72) for acidic conditions associated with the minimum RWST boron concentration. (As noted in the 11/5/15 meeting, maximizing this value does not significantly increase predicted aluminum release)

• The design basis maximum containment pool pH (~8.1, may change with planned revision to the pH calculation) is used for the sprays during recirculation and the containment pool to calculate chemical release. (a high pH maximizes the calculated aluminum and calcium release, see new slide on effect of pH on calcium release from fiberglass)

• Lower pH values/profiles (7.0) are used for aluminum solubility to account for lower TSP concentrations, higher boric acid concentrations, and pH effects due to core release and radiolysis. (a low pH minimizes the calculated solubility of aluminum) 3

CHEMICAL EFFECTS (NOVEMBER 5, 2015 MEETING, UPDATES/CHANGES IN RED)

• Overview

• Chemical precipitate quantities are determined for each break

• Corrosion/Dissolution Model

• Dissolution from insulation and concrete is determined using the WCAP-16530 equations

• Corrosion, dissolution and passivation of aluminum metal is determined using the equations developed by Howe et al. (UNM)

• Solubility

• No credit will be taken for calcium solubility

• ANL solubility equation (ML091610696, Eq. 4) will be used to credit delayed aluminum precipitation

• Once temperature limit is reached, all aluminum is forced to precipitate

• By 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, Aluminum is eventually "forced" to precipitate for all breaks

• Precipitate Surrogates

• WCAP-16530 Calcium Phosphate 4

• WCAP-16530 Sodium Aluminum Silicate

CALCIUM RELEASE FROM VOGTLE SPECIFIC MATERIALS

• Calcium Release: Sump pH = 7.0

• Calcium Release Sump pH = 8.1

• WCAP-16530 shows a higher sump pH increases the quantity of calcium released from fiberglass. Calcium silicate is not present in Vogtles containments.

5

USE OF THE UNM EQUATION

, =

1000 ( )

6.2181 4.6454 +1.7716 ( )1.9550

= 10 1000 0.85586 4.9561x10 3 +7.1978x10 6 2

=

• Developed from testing performed at temperatures between 131°F and 185°F and pH values between 6.84 and 7.84

• Using the WCAP-17788 tests, the applicable ranges are extended to [104.8°F, 262.1°F]* and pH 8.1**

• *see slide discussing the temperature constraints for the passivation term, P

• **tTSP = 0 min (P = 1) for pH values below 6.84

• Note that the temperatures used in the equations, TK and TKP, are in Kelvin 6

USE OF THE UNM EQUATION

• Curve Fits of UNM Aluminum Experiments

• These figures, excerpted from Howe et al., show how the correlations were initially fit to the bench test data.

7

USE OF THE UNM EQUATION

• Comparison of UNM Rmax and 2xWCAP Al Release Rates

• The UNM release rate (w/o passivation) 8 increases faster, especially at pH > 7.5

USE OF THE UNM EQUATION

• UNM Al Passivation Term Passivation term is limited to a range of temperatures Passivation term results in an under-prediction of Al corrosion for high and low temperatures

• TKP = TK unless:

• below 328.15K, TKP = 328.15K (131°F, 55°C) 9

• above 358.15 K, TKP = 358.15 K (185°F, 85°C)

EXAMPLE CALCULATION 1 MAXIMUM CHEMICAL QUANTITY

• Maximum Chemical Product Generation Inputs

• Break Location with maximum fiberglass generated

• CS duration for chemical effects: 30 days

• Design basis temperature profile - Minimum Safeguards

• Maximum water volume

• Sump pH used for corrosion: 8.1

• Containment spray pH during Injection used for corrosion: 5.72

• pH used for solubility: 7.0

• Submerged Aluminum Area: 348.4 ft2

• Unsubmerged Aluminum Area: 926.6 ft2

• Submerged Concrete: 10,000 ft2

• Aluminum Metal Release equations - Howe et al. (UNM) w/Passivation

• Aluminum Solubility Equation - ANL Equation 4

• Aluminum Solubility: Timing Only 10

EXAMPLE CALCULATION 1 CHEMICAL PRECIPITATE QUANTITIES

• Chemical Precipitate Quantities 11

EXAMPLE CALCULATION 1 CHEMICAL RELEASE (30 DAYS)

• Aluminum Release/Corrosion

• Calcium Release

• The quantity of submerged EGlass and the exposure of unsubmerged aluminum metal to containment spray are linked to break size under the current approach for Vogtle.

12

EXAMPLE CALCULATION 1 ALUMINUM CONCENTRATION AND SOLUBILITY (FIRST 5 DAYS)

• Aluminum Concentration and Solubility 13

EXAMPLE CALCULATION 1 AL PRECIPITATION TEMPERATURE MARGIN (FIRST 5 DAYS)

• Aluminum Precipitation and Sump Temperature 14

EXAMPLE CALCULATION 1 UNM EQUATION AND WCAP-16530-NP-A (FIRST 24 HOURS)

• Comparison of UNM and WCAP Al Predictions

• Note that the 2X multiplier required by the Safety Evaluation for Al release from Al metal is used for the WCAP-16530-NP-A prediction.

• The WCAP-16530-NP-A (2X for 15 days) prediction reaches 5.84 ppm at 30 days

• Note that the UNM prediction uses WCAP-16530-NP-A for non-metal materials and the 15 Howe et al. equations w/passivation for aluminum metal

EXAMPLE CALCULATION 2 MAXIMUM CHEMICAL QUANTITY W/BEST ESTIMATE TEMPERATURE

• Illustrates sensitivity of chemical release and precipitation to temperature by using a best estimate temperature profile

• Chemical Product Generation Inputs

• Break Location with maximum fiberglass generated

• CS duration for chemical effects: 30 days

• Best estimate temperature profile - DEGB Primary Loop

• Design basis used after 10.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> (Limit of TAMU calculations).

• Maximum water volume

• Sump pH used for corrosion: 8.1

• Containment spray pH during Injection used for corrosion: 5.72

• pH used for solubility: 7.0

• Submerged Aluminum Area: 348.4 ft2

• Unsubmerged Aluminum Area: 926.6 ft2

• Submerged Concrete: 10,000 ft2

• Aluminum Metal Release equations - Howe et al. (UNM) w/Passivation

• Aluminum Solubility Equation - ANL Equation 4

• Aluminum Solubility: Timing Only 16

EXAMPLE CALCULATION 2 CHEMICAL RELEASE (30 DAYS) FOR A B.E. TEMPERATURE PROFILE

• Chemical Precipitate Quantities

• Compare with Slide 11 of Example Calculation 1

• Note: Solubility past 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (shown here) would not be credited.

• Calcium phosphate does not decrease significantly due to the 17 use of the design basis temperature profile after 10.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.

WCAP-17788 AND ANL SOLUBILITY

• Aluminum Solubility Map (next slide)

• Vogtle Results and ANL Solubility Equation are compared with the autoclave test results using a Solubility Map per WCAP-17788-NP, Vol. 1, Section 6.2, Option 2.

• The maximum calculated aluminum concentration at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is 2.818 ppm.

• The ANL Equation predicts precipitation of 2.818 ppm of Aluminum at ~140°F using a pH of 7.0 for solubility (note:

chemical release is calculated with a pH of 8.1).

• Autoclave test data from WCAP-17788-P, Volume 5 for tests using TSP (WEC proprietary, not shown) demonstrate that aluminum precipitation will not occur within a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration for:

• pH + p[Al] > ~11 (2.818 ppm Al; pH = 7.0) 18

• Temperatures > 70°F

WCAP-17788 AND ANL SOLUBILITY

• Aluminum Solubility Map No Precipitation Predicted Precipitation Predicted

• Note that 2.818 ppm is the maximum calculated concentration of aluminum at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> using a pH of 8.1 for chemical release, which maximizes aluminum corrosion.

19

HOWE AND ANL SOLUBILITY

• Solubility will be credited for a maximum of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />

• WCAP-17788 Autoclave tests were only performed for a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period

• All dissolved aluminum will be considered to form precipitate

• The Howe et al. manuscript proposed an equation for aluminum solubility that bounded the CHLE T3 and T4 excess aluminum test results.

• The Howe equation predicts aluminum precipitation at higher temperatures, lower Al concentrations, and higher pH conditions than ANL Equation 4.

• Aluminum precipitation in the CHLE T3 and T4 tests occurred gradually (several days) after an extended duration at high temperature and during a slow decrease in temperature

• Autoclave test data from WCAP-17788-P, Volume 5 for 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> tests using TSP where precipitation was not detected support ANL Eq. 4 as bounding.

• Therefore, ANL Eq. 4 is only credited by Vogtle to bound short-term aluminum solubility in TSP 20

HOWE AND ANL SOLUBILITY

• Aluminum Solubility Map No Precipitation Predicted Precipitation Predicted 21

CONCLUSIONS

• The design basis maximum pH will be used for chemical release and a less than design basis minimum of 7.0 will be used for solubility.

• Unlike calcium silicate, calcium release from fiberglass increases with pH

• The Vogtle chemical effects model for strainer head loss will use:

• Howe et al. (UNM) aluminum corrosion/passivation equations

• WCAP-16530-NP-A aluminum/calcium release equations for non-metallic sources

• ANL Equation 4 to credit delayed aluminum precipitation up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 22

VOGTLE GSI-191 RESOLUTION PLAN: FOLLOW-UP ON CHEMICAL EFFECTS MARCH 2, 2016

PURPOSE OF MEETING

• Address topics on chemical effects from the November 5th, 2015 meeting

• Clarify pH Values used for Release and Solubility

• Discuss Calcium Release Rate vs. pH

• Detail Implementation of the Howe et al. (UNM) Aluminum Corrosion Equations

• Summarize Use of WCAP-17788 Testing with the ANL Equations to Support Short Term Aluminum Solubility 2

CONTAINMENT SPRAY AND POOL pH (NOVEMBER 5, 2015 MEETING, UPDATES/CHANGES IN RED)

Combining conditions in a non-physical way to bound release and precipitation

• Containment spray from the RWST will use a maximum pH (5.72) for acidic conditions associated with the minimum RWST boron concentration. (As noted in the 11/5/15 meeting, maximizing this value does not significantly increase predicted aluminum release)

• The design basis maximum containment pool pH (~8.1, may change with planned revision to the pH calculation) is used for the sprays during recirculation and the containment pool to calculate chemical release. (a high pH maximizes the calculated aluminum and calcium release, see new slide on effect of pH on calcium release from fiberglass)

• Lower pH values/profiles (7.0) are used for aluminum solubility to account for lower TSP concentrations, higher boric acid concentrations, and pH effects due to core release and radiolysis. (a low pH minimizes the calculated solubility of aluminum) 3

CHEMICAL EFFECTS (NOVEMBER 5, 2015 MEETING, UPDATES/CHANGES IN RED)

• Overview

• Chemical precipitate quantities are determined for each break

• Corrosion/Dissolution Model

• Dissolution from insulation and concrete is determined using the WCAP-16530 equations

• Corrosion, dissolution and passivation of aluminum metal is determined using the equations developed by Howe et al. (UNM)

• Solubility

• No credit will be taken for calcium solubility

• ANL solubility equation (ML091610696, Eq. 4) will be used to credit delayed aluminum precipitation

• Once temperature limit is reached, all aluminum is forced to precipitate

• By 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, Aluminum is eventually "forced" to precipitate for all breaks

• Precipitate Surrogates

• WCAP-16530 Calcium Phosphate 4

• WCAP-16530 Sodium Aluminum Silicate

CALCIUM RELEASE FROM VOGTLE SPECIFIC MATERIALS

• Calcium Release: Sump pH = 7.0

• Calcium Release Sump pH = 8.1

• WCAP-16530 shows a higher sump pH increases the quantity of calcium released from fiberglass. Calcium silicate is not present in Vogtles containments.

5

USE OF THE UNM EQUATION

, =

1000 ( )

6.2181 4.6454 +1.7716 ( )1.9550

= 10 1000 0.85586 4.9561x10 3 +7.1978x10 6 2

=

• Developed from testing performed at temperatures between 131°F and 185°F and pH values between 6.84 and 7.84

• Using the WCAP-17788 tests, the applicable ranges are extended to [104.8°F, 262.1°F]* and pH 8.1**

• *see slide discussing the temperature constraints for the passivation term, P

• **tTSP = 0 min (P = 1) for pH values below 6.84

• Note that the temperatures used in the equations, TK and TKP, are in Kelvin 6

USE OF THE UNM EQUATION

• Curve Fits of UNM Aluminum Experiments

• These figures, excerpted from Howe et al., show how the correlations were initially fit to the bench test data.

7

USE OF THE UNM EQUATION

• Comparison of UNM Rmax and 2xWCAP Al Release Rates

• The UNM release rate (w/o passivation) 8 increases faster, especially at pH > 7.5

USE OF THE UNM EQUATION

• UNM Al Passivation Term Passivation term is limited to a range of temperatures Passivation term results in an under-prediction of Al corrosion for high and low temperatures

• TKP = TK unless:

• below 328.15K, TKP = 328.15K (131°F, 55°C) 9

• above 358.15 K, TKP = 358.15 K (185°F, 85°C)

EXAMPLE CALCULATION 1 MAXIMUM CHEMICAL QUANTITY

• Maximum Chemical Product Generation Inputs

• Break Location with maximum fiberglass generated

• CS duration for chemical effects: 30 days

• Design basis temperature profile - Minimum Safeguards

• Maximum water volume

• Sump pH used for corrosion: 8.1

• Containment spray pH during Injection used for corrosion: 5.72

• pH used for solubility: 7.0

• Submerged Aluminum Area: 348.4 ft2

• Unsubmerged Aluminum Area: 926.6 ft2

• Submerged Concrete: 10,000 ft2

• Aluminum Metal Release equations - Howe et al. (UNM) w/Passivation

• Aluminum Solubility Equation - ANL Equation 4

• Aluminum Solubility: Timing Only 10

EXAMPLE CALCULATION 1 CHEMICAL PRECIPITATE QUANTITIES

• Chemical Precipitate Quantities 11

EXAMPLE CALCULATION 1 CHEMICAL RELEASE (30 DAYS)

• Aluminum Release/Corrosion

• Calcium Release

• The quantity of submerged EGlass and the exposure of unsubmerged aluminum metal to containment spray are linked to break size under the current approach for Vogtle.

12

EXAMPLE CALCULATION 1 ALUMINUM CONCENTRATION AND SOLUBILITY (FIRST 5 DAYS)

• Aluminum Concentration and Solubility 13

EXAMPLE CALCULATION 1 AL PRECIPITATION TEMPERATURE MARGIN (FIRST 5 DAYS)

• Aluminum Precipitation and Sump Temperature 14

EXAMPLE CALCULATION 1 UNM EQUATION AND WCAP-16530-NP-A (FIRST 24 HOURS)

• Comparison of UNM and WCAP Al Predictions

• Note that the 2X multiplier required by the Safety Evaluation for Al release from Al metal is used for the WCAP-16530-NP-A prediction.

• The WCAP-16530-NP-A (2X for 15 days) prediction reaches 5.84 ppm at 30 days

• Note that the UNM prediction uses WCAP-16530-NP-A for non-metal materials and the 15 Howe et al. equations w/passivation for aluminum metal

EXAMPLE CALCULATION 2 MAXIMUM CHEMICAL QUANTITY W/BEST ESTIMATE TEMPERATURE

• Illustrates sensitivity of chemical release and precipitation to temperature by using a best estimate temperature profile

• Chemical Product Generation Inputs

• Break Location with maximum fiberglass generated

• CS duration for chemical effects: 30 days

• Best estimate temperature profile - DEGB Primary Loop

• Design basis used after 10.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> (Limit of TAMU calculations).

• Maximum water volume

• Sump pH used for corrosion: 8.1

• Containment spray pH during Injection used for corrosion: 5.72

• pH used for solubility: 7.0

• Submerged Aluminum Area: 348.4 ft2

• Unsubmerged Aluminum Area: 926.6 ft2

• Submerged Concrete: 10,000 ft2

• Aluminum Metal Release equations - Howe et al. (UNM) w/Passivation

• Aluminum Solubility Equation - ANL Equation 4

• Aluminum Solubility: Timing Only 16

EXAMPLE CALCULATION 2 CHEMICAL RELEASE (30 DAYS) FOR A B.E. TEMPERATURE PROFILE

• Chemical Precipitate Quantities

• Compare with Slide 11 of Example Calculation 1

• Note: Solubility past 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (shown here) would not be credited.

• Calcium phosphate does not decrease significantly due to the 17 use of the design basis temperature profile after 10.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.

WCAP-17788 AND ANL SOLUBILITY

• Aluminum Solubility Map (next slide)

• Vogtle Results and ANL Solubility Equation are compared with the autoclave test results using a Solubility Map per WCAP-17788-NP, Vol. 1, Section 6.2, Option 2.

• The maximum calculated aluminum concentration at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is 2.818 ppm.

• The ANL Equation predicts precipitation of 2.818 ppm of Aluminum at ~140°F using a pH of 7.0 for solubility (note:

chemical release is calculated with a pH of 8.1).

• Autoclave test data from WCAP-17788-P, Volume 5 for tests using TSP (WEC proprietary, not shown) demonstrate that aluminum precipitation will not occur within a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> duration for:

• pH + p[Al] > ~11 (2.818 ppm Al; pH = 7.0) 18

• Temperatures > 70°F

WCAP-17788 AND ANL SOLUBILITY

• Aluminum Solubility Map No Precipitation Predicted Precipitation Predicted

• Note that 2.818 ppm is the maximum calculated concentration of aluminum at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> using a pH of 8.1 for chemical release, which maximizes aluminum corrosion.

19

HOWE AND ANL SOLUBILITY

• Solubility will be credited for a maximum of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />

• WCAP-17788 Autoclave tests were only performed for a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period

• All dissolved aluminum will be considered to form precipitate

• The Howe et al. manuscript proposed an equation for aluminum solubility that bounded the CHLE T3 and T4 excess aluminum test results.

• The Howe equation predicts aluminum precipitation at higher temperatures, lower Al concentrations, and higher pH conditions than ANL Equation 4.

• Aluminum precipitation in the CHLE T3 and T4 tests occurred gradually (several days) after an extended duration at high temperature and during a slow decrease in temperature

• Autoclave test data from WCAP-17788-P, Volume 5 for 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> tests using TSP where precipitation was not detected support ANL Eq. 4 as bounding.

• Therefore, ANL Eq. 4 is only credited by Vogtle to bound short-term aluminum solubility in TSP 20

HOWE AND ANL SOLUBILITY

• Aluminum Solubility Map No Precipitation Predicted Precipitation Predicted 21

CONCLUSIONS

• The design basis maximum pH will be used for chemical release and a less than design basis minimum of 7.0 will be used for solubility.

• Unlike calcium silicate, calcium release from fiberglass increases with pH

• The Vogtle chemical effects model for strainer head loss will use:

• Howe et al. (UNM) aluminum corrosion/passivation equations

• WCAP-16530-NP-A aluminum/calcium release equations for non-metallic sources

• ANL Equation 4 to credit delayed aluminum precipitation up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 22