1CAN100801, Supplemental Information for Sodium Hydroxide Tank Concentration License Amendment Request

Supplemental Information for Sodium Hydroxide Tank Concentration License Amendment Request

ML082770149
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/02/2008
From:	Mitchell T Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
1CAN100801
Download: ML082770149 (5)

Text

Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802 Tel 479-858-3110 Timothy G. Mitchell Vice President, Operations Arkansas Nuclear One 1CAN100801 October 2, 2008 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Subject:

Supplemental Information for Sodium Hydroxide Tank Concentration License Amendment Request Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51

Dear Sir or Madam:

By letter dated October 1, 2008 (0CNA100801), the NRC requested that supplemental information be provided for the sodium hydroxide (NaOH) tank concentration license amendment request for Arkansas Nuclear One, Unit 1 (ANO-1). The attachment to this submittal contains the requested information.

There are no new commitments contained in this submittal. If you have any questions or require additional information, please contact Dale James at 479-858-4619.

I declare under penalty of perjury that the foregoing is true and correct. Executed on October 2, 2008.

Sincerely, TGM/nbm Attachment - Supplemental Information - Sodium Hydroxide Tank Concentration License Amendment Request

1CAN100801 Page 2 cc: Mr. Elmo E. Collins Regional Administrator U. S. Nuclear Regulatory Commission Region IV 612 Lamar Blvd., Suite 400 Arlington, TX 76011-4125 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 U.S. Nuclear Regulatory Commission Attn: Mr. Alan B. Wang MS O-7 D1 Washington, DC 20555-0001 Mr. Bernard R. Bevill Director Division of Radiation Control and Emergency Management Arkansas Department of Health & Human Services P.O. Box 1437 Slot H-30 Little Rock, AR 72203-1437

Attachment to 1CAN100801 Supplemental Information Sodium Hydroxide Tank Concentration License Amendment Request

Attachment to 1CAN100801 Page 1 of 2 Supplemental Information Sodium Hydroxide Tank Concentration License Amendment Request

1. To enable the NRC staff to evaluate that reducing the maximum concentration will reduce the amounts of GSI-191 chemical precipitates, show that the reduction in maximum NaOH concentration will result in reduced chemical effects and provide the calculated quantity of chemical precipitates, by species, before and after the proposed change.

The ANO-1 chemical effects are associated with aluminum release and associated precipitates. A maximum sump pH of 10.5 was determined for the original NaOH concentration range. The revised NaOH concentration range supports a maximum sump pH of 9.0. The corrosion rate of aluminum materials increases with increased pH values in accordance with the results of the WCAP-16530-NP spreadsheet model. This model was used as the basis for determining chemical effects precipitates that need to be addressed for the post-loss-of-coolant accident (LOCA) environment.

The results from the WCAP-16530-NP spreadsheet model for the same inputs with sump recirculation maximum pH of 10.5 and 9.0 are shown below:

pH 10.5 pH 9.0 Aluminum Released (kg): 109.0 41.3 Sodium Aluminum Silicate precipitate (kg): 91.4 91.4 Aluminum Oxyhydroxide precipitate (kg): 221.1 70.9 As shown above, the mass of released aluminum at a pH of 9.0 is reduced by over 60%

compared to the aluminum mass released at a pH of 10.5 based on the modeled proportions of thick and thin aluminum for ANO-1.

2. To enable the NRC staff to evaluate that the sump pH will remain greater than 7.0 over the period of 30 days post-LOCA, the licensee is requested to provide the following information.

• Provide the maximum concentration of strong acid concentrations in the sump for a period of 30 days post-LOCA.

The maximum strong acids generated following a LOCA at ANO-1 are:

• Cable-generated hydrochloric acid (HCl) in sump water = 1.52 x 10-3 moles/liter

• Sump-generated nitric acid (HNO3) in sump water = 5.85 x 10-5 moles/liter These values are based on the 30-day integrated dose values from a LOCA with conservative volumes of cable insulation and sump water.

Attachment to 1CAN100801 Page 2 of 2

• Describe the analysis methodology used to determine the pH in the sump water during a period of 30 days post-LOCA. Include detailed calculations of the minimum pH values in the sump during a 30-day period post-LOCA to demonstrate that the pH remains greater than 7.0 throughout this time period.

Equilibrium sump pH was determined by considering a single point. The most important time for sump pH calculations is at the beginning of recirculation after all the borated water and NaOH that is to be added is present. Additional strong acids generated from cable insulation and sump fluids under accident radiation levels were added to the equation. The bounding values used were 1.52 x 10-3 moles/liter (54 ppm) for HCl and 5.85 x 10-5 moles/liter (3.6 ppm) for HNO3 based on a 30-day integrated dose for a LOCA. The minimum pH evaluation used the maximum borated water source volumes and concentrations with the minimum NaOH tank volume (4,000 gallons) to determine the concentration needed to ensure an equilibrium sump pH greater than 7.0. The analysis shows that maintaining a NaOH tank concentration of greater than 5.53 wt%

with other ANO-1 Technical Specification (TS) boron concentration limits results in a long-term sump pH of greater than 7.0. The proposed TS minimum NaOH concentration value of 6.0 wt% exceeds the analyzed value to ensure the equilibrium sump pH is greater than 7.0, including the addition of strong acids.

• If a computer program was used, describe the code and provide the input and output data of the program.

The computer program used was MULTEQ-REDOX Version 2.24 from the Electric Power Research Institute. A summary of the inputs for the borated water storage tank (BWST), core flood tanks (CFTs), and reactor coolant system (RCS) is as follows:

Source/ Volume Concentration Concentration Vol. x Conc.

Chemical (gal) (ppm) (moles/liter) (gal-moles/liter)

BWST/Boron 406,029 2670 0.247 100,379 CFTs/Boron 17,202 3500 0.324 5,575 RCS/Boron 62,122 2270 0.210 13,057 NaOH Tank 4,000 calculated calculated calculated Totals 489,353 n/a n/a 119,011 The above values result in a sump boron concentration of 15,040 ppm. Additional strong acids generated from cable insulation and sump fluids under accident radiation levels were added to the equation as discussed above. The derived NaOH value of 5.53 wt% (1.46871 moles/liter or 276 ppm) results in an equilibrium sump water pH of at least 7.0. Therefore, any concentration value of the NaOH tank above 5.53 wt%

ensures that the worst case combination of sump water fluids exceeds a pH value of 7.0.