L-2019-206, Environmental Protection Plan, Minor Permit Revision Request for Chlorine Dioxide

From kanterella
Jump to navigation Jump to search
Environmental Protection Plan, Minor Permit Revision Request for Chlorine Dioxide
ML19330D242
Person / Time
Site: Saint Lucie  NextEra Energy icon.png
Issue date: 11/25/2019
From: Godes W
Florida Power & Light Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
EPP 3.2.4, FL0002208, L-2019-206
Download: ML19330D242 (18)
v • d • e


Text

. **1 ;- ~' ****.* .-.*.--_-.*.-.'

NOV 2 *5 201S L-2019-206 10 CFR 50.4 EPP 3.2.4 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 Environmental Protection Plan IWW Permit No. FL0002208 Minor Permit Revision Request for Chlorine Dioxide Pursuant to Section 3.2.4 of the St. Luc* * - rotection Plan, Florida Power & Light Company (FPL) is hereb closed letter proposing a minor revision to the Industrial Wastewr:. )ermit (Permit Number FL0002208).

Please contact Seth Duston (772) 467-7144 should you have any questions on this matter.

Sincerely, W7#lt/~

  • vvyatt ~s-Licensing Manager St. Lucie Plant WG/rcs Enclosure Florida Power & Ught Company 650i S. Ocean Driv~. Jensen Beach, FL 34957

NOV 2 5 2019 SDPSL-2019-063 Marc Harris, P.E.

Florida Department of Environmental Protection 2600 Blair Stone Road Tallahassee, Florida 32399-2400 Re: Florida Power & Light Company Plant St. Lucie Wastewater Permit No. FL0002208 Minor Permit Revision Request for Chlorine Dioxide

Dear Mr. Harris:

FPL St. Lucie Plant requests a Minor Permit Revision to Industrial Wastewater Permit No. FL0002208 Section l.C.9 to include Chlorine Dioxide as a permanently approved biocide. As part of the Chlorine Optimization Study required by Section Vl.5 of FL0002208, the plant conducted a pilot trial using the Nalco Purate System to examine the benefit of using Chlorine Dioxide to prevent biofouling in lieu of using Sodium Hypochlorite. Both ATP (Adenosine Triphosphate) and residual chlorine analyses during the study showed improved biocide effectiveness on a microbiological level.

Condenser inspections performed during the Unit 1 fall refueling outage in October confirmed that enhanced disinfection and macro biological fouling prevention was achieved with this alternative biocide.

FPL St. Lucie Plant also requests to maintain sodium hypochlorite on the approved chemicals list in conjunction with chlorine dioxide in section l.C.9. Post permanent implementation of this new biocide, the sodium hypochlorite system will be maintained as a backup to guarantee site capability to treat Intake Cooling Water (service water),

which affects the health of nuclear safety related heat exchangers.

Use of the Nalco Purate System would involve bulk storage of the following chemicals:

Name Purpose CERCLARQ Purate (40%

Sodium Chlorite, Biocide Precursor N/A 7% Hydrogen Peroxide)

Biocide Production 78% Sulfuric Acid 1000 lbs Reagent Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957

SDPSL-2019-063 Page 2 The following information is provided in Attachment 1 in support of this request:

1. Nalco Pu rate process illustration (Figure 1)
2. Projected Dosage
3. Estimated Effluent Residual
4. Applicable byproduct toxicity data
5. Applicable residual chlorine dioxide toxicity data
6. Safety Data Sheets for Nalco Purate (proprietary)
7. Safety Data Sheets for Nalco 78% Sulfuric Acid This information, along with the effluent toxicity test results submitted during the trial period, adequately demonstrate that use of this new chemical will pose no concerns with toxicity. If you should have any questions or require additional information regarding this request, please feel free to contact Chrissi-Lee Ramsey at (772) 467-7228 or via email at Chrissi-Lee.Ramsey@fpl.com.

Sincerely, Daniel DeBoer Site Director St. Lucie Power Plant Attachments:

1. Supporting Information
2. Minor Permit Revision Application cc: FPL - William Nurnberger FPL - Seth Duston FPL - Peter Polfleit FPL- Ron Hix FDEP - Southeast District Office FDEP - Siting Coordination Office

SDPSL-2019-063 Page 3 - Supporting Information Figure 1: Purate Process Illustration

SDPSL-2019-063 Page 4 Estimated Dosage Assuming pH = 7.6 and Tintake = 77°F (Average intake conditions in the winter)

  • Based on Pilot Trial Sample Results Condenser Cooling Water Intake Cooling Water Biocide NaClO ClO2 NaClO ClO2 Dosage 3.6 ppm 1.12 ppm 3.8 ppm 0.8 ppm 30 mins per well, per 30 mins per well, per Frequency Continuous Continuous day (120 mins total) day (120 mins total)

Assuming pH = 7.6 and Tintake = 86°F (Average intake conditions in the summer)

  • Based on Pilot Trial Sample Results Condenser Cooling Water Intake Cooling Water Biocide NaClO ClO2 NaClO ClO2 Dosage 3.6 ppm 1.00 ppm 3.8 ppm 0.6 ppm 30 mins per well, per 30 mins per well, per Frequency Continuous Continuous day (120 mins total) day (120 mins total)

Estimated Effluent Residual Pilot trial total residual chlorine data has proven that St. Lucie plant effluent will be below the enforceable limit of 0.1 ppm at EFF-2 during injection.

SDPSL-2019-063 Page 5 Byproduct Toxicity Organism Test ClO2- (Chlorite) ClO3- (Chlorate)

Mysid Shrimp LC50 (96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) 0.576 ppm >1000 ppm Sheepshead Minnow LC50 (96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) 75 ppm >1000 ppm

  • EPA-HQ-OPP-2006-0328-0020: Environmental Fate and Ecological Risk Assessment for the Reregistration of Sodium Chlorate as an Active Ingredient in Terrestrial Food/Feed and Non-food/Non-feed uses*

Residual Chlorine Dioxide Toxicity Organism Test ClO2 Sheepshead Minnow LC50 (96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) 0.02 - 0.17 ppm Bluegill Sunfish LC50 (96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) 0.15 ppm

  • Sourced from Nalco Water Global Regulatory Affairs Department*

SDPSL-2019-063 Page 6 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max Section: 1. PRODUCT AND COMPANY IDENTIFICATION Product name  : Chlorine Dioxide Dissolved in water 4000 ppm max Other means of identification : Not applicable.

Restrictions on use  : Refer to available product literature or ask your local Sales Representative for restrictions on use and dose limits.

Company  : Nalco Company 1601 W. Diehl Road Naperville, Illinois 60563-1198 USA TEL: (630)305-1000 Emergency telephone  : (800) 424-9300 (24 Hours) CHEMTREC number Issuing date  : 03/16/2016 Section: 2. HAZARDS IDENTIFICATION GHS Classification Not a hazardous substance or mixture.

GHS Label element Precautionary Statements  : Prevention:

Wash hands thoroughly after handling.

Response

Specific measures: consult SDS Section 4.

Storage:

Store in accordance with local regulations.

Other hazards  : None known.

Section: 3. COMPOSITION/INFORMATION ON INGREDIENTS Pure substance/mixture  : Mixture Chemical Name CAS-No. Concentration: (%)

Chlorine Dioxide 10049-04-4 <= 0.4 Section: 4. FIRST AID MEASURES In case of eye contact  : Rinse with plenty of water. Get medical attention if symptoms occur.

In case of skin contact  : Wash off with soap and plenty of water. Get medical attention if symptoms occur.

If swallowed  : Rinse mouth. Get medical attention if symptoms occur.

If inhaled  : Get medical attention if symptoms occur.

1/9

SDPSL-2019-063 Page 7 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max Protection of first-aiders  : In event of emergency assess the danger before taking action. Do not put yourself at risk of injury. If in doubt, contact emergency responders. Use personal protective equipment as required.

Notes to physician  : Treat symptomatically.

Most important symptoms  : See Section 11 for more detailed information on health effects and symptoms.

and effects, both acute and delayed Section: 5. FIREFIGHTING MEASURES Suitable extinguishing media : Use extinguishing measures that are appropriate to local circumstances and the surrounding environment.

Unsuitable extinguishing  : None known.

media Specific hazards during  : Not flammable or combustible.

firefighting Hazardous combustion  : Carbon oxides products Special protective equipment : Use personal protective equipment.

for firefighters Specific extinguishing  : Fire residues and contaminated fire extinguishing water must be disposed of in methods accordance with local regulations.

Section: 6. ACCIDENTAL RELEASE MEASURES Personal precautions,  : Refer to protective measures listed in sections 7 and 8.

protective equipment and emergency procedures Environmental precautions  : No special environmental precautions required.

Methods and materials for  : Stop leak if safe to do so. Contain spillage, and then collect with non-containment and cleaning up combustible absorbent material, (e.g. sand, earth, diatomaceous earth, vermiculite) and place in container for disposal according to local / national regulations (see section 13). Flush away traces with water. For large spills, dike spilled material or otherwise contain material to ensure runoff does not reach a waterway.

Section: 7. HANDLING AND STORAGE Advice on safe handling  : For personal protection see section 8. Wash hands after handling.

Conditions for safe storage  : Keep away from strong bases. Keep out of reach of children. Keep container tightly closed. Store in suitable labeled containers.

2/9

SDPSL-2019-063 Page 8 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max Suitable material  : The following compatibility data is suggested based on similar product data and/or industry experience: Compatibility with Plastic Materials can vary; we therefore recommend that compatibility is tested prior to use.

Unsuitable material  : not determined Section: 8. EXPOSURE CONTROLS/PERSONAL PROTECTION Components with workplace control parameters Exposure guidelines have not been established for this product. Available exposure limits for the substance(s) are shown below.

Components CAS-No. Form of exposure Permissible Basis concentration Chlorine Dioxide 10049-04-4 TWA 0.1 ppm ACGIH STEL 0.3 ppm ACGIH STEL 0.3 ppm NIOSH REL 0.9 mg/m3 TWA 0.1 ppm NIOSH REL 0.3 mg/m3 TWA 0.1 ppm OSHA Z1 0.3 mg/m3 Engineering measures  : Good general ventilation should be sufficient to control worker exposure to airborne contaminants.

Personal protective equipment Eye protection  : Safety glasses Hand protection  : Wear protective gloves.

Gloves should be discarded and replaced if there is any indication of degradation or chemical breakthrough.

Skin protection  : Wear suitable protective clothing.

Respiratory protection  : No personal respiratory protective equipment normally required.

Hygiene measures  : Wash hands before breaks and immediately after handling the product.

Section: 9. PHYSICAL AND CHEMICAL PROPERTIES Appearance  : Liquid Colour  : Light yellow Odour  : Chlorine Flash point  : does not flash 3/9

SDPSL-2019-063 Page 9 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max pH  : no data available Odour Threshold  : no data available Melting point/freezing point  : no data available Initial boiling point and boiling : no data available range Evaporation rate  : no data available Flammability (solid, gas)  : no data available Upper explosion limit  : no data available Lower explosion limit  : no data available Vapour pressure  : 5.0 mm Hg, (25.0 °C),

Relative vapour density  : no data available Relative density  : no data available Density  : no data available Water solubility  : completely soluble Solubility in other solvents  : no data available Partition coefficient: n-  : no data available octanol/water Auto-ignition temperature  : no data available Thermal decomposition  : no data available temperature Viscosity, dynamic  : no data available Viscosity, kinematic  : no data available Molecular weight  : no data available VOC  : 0 %, Calculation method Section: 10. STABILITY AND REACTIVITY Chemical stability  : Stable under normal conditions.

Possibility of hazardous  : No dangerous reaction known under conditions of normal use.

reactions Conditions to avoid  : None known.

Incompatible materials  : Do not bring in contact with organic materials and reducing agents.

Hazardous decomposition  : Chlorine, Chlorine dioxide products Carbon oxides Section: 11. TOXICOLOGICAL INFORMATION Information on likely routes of  : Inhalation, Eye contact, Skin contact exposure 4/9

SDPSL-2019-063 Page 10 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max Potential Health Effects Eyes  : Health injuries are not known or expected under normal use.

Skin  : Health injuries are not known or expected under normal use.

Ingestion  : Health injuries are not known or expected under normal use.

Inhalation  : Health injuries are not known or expected under normal use.

Chronic Exposure  : Health injuries are not known or expected under normal use.

Experience with human exposure Eye contact  : No symptoms known or expected.

Skin contact  : No symptoms known or expected.

Ingestion  : No symptoms known or expected.

Inhalation  : No symptoms known or expected.

Toxicity Product Acute oral toxicity  : Acute toxicity estimate : > 5,000 mg/kg Acute inhalation toxicity  : Acute toxicity estimate : > 40 mg/l Exposure time: 4 h Acute toxicity estimate : > 40 mg/l Exposure time: 4 h Acute dermal toxicity  : no data available Skin corrosion/irritation  : no data available Serious eye damage/eye  : no data available irritation Respiratory or skin  : no data available sensitization Carcinogenicity  : no data available Reproductive effects  : no data available Germ cell mutagenicity  : no data available Teratogenicity  : no data available 5/9

SDPSL-2019-063 Page 11 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max STOT - single exposure  : Based on available data, the classification criteria are not met.

STOT - repeated exposure  : no data available Aspiration toxicity  : no data available Section: 12. ECOLOGICAL INFORMATION Ecotoxicity Environmental Effects  : This product has no known ecotoxicological effects.

Product Toxicity to fish  : LC50 Rainbow Trout: 2.2 mg/l Exposure time: 96 hrs Test substance: Active Substance LC50 Bluegill Sunfish: > 100 mg/l Exposure time: 96 hrs Test substance: Active Substance LC50 Inland Silverside: > 0.4 mg/l Exposure time: 96 hrs Test substance: Active Substance Toxicity to daphnia and other  : EC50 Daphnia pulex: 1.8 mg/l aquatic invertebrates Exposure time: 48 hrs Test substance: Active Substance Toxicity to fish (Chronic  : NOEC: 0.15 mg/l toxicity) Exposure time: 20 d Species: Rainbow Trout Test substance: Active Substance Persistence and degradability Greater than 95% of this product consists of inorganic substances for which a biodegradation value is not applicable.

Mobility The environmental fate was estimated using a level III fugacity model embedded in the EPI (estimation program interface) Suite TM, provided by the US EPA. The model assumes a steady state condition between the total input and output. The level III model does not require equilibrium between the defined media. The information provided is intended to give the user a general estimate of the environmental fate of this product under the defined conditions of the models.

If released into the environment this material is expected to distribute to the air, water and soil/sediment in the approximate respective percentages; Air  : <5%

Water  : 30 - 50%

Soil  : 50 - 70%

The portion in water is expected to be soluble or dispersible.

6/9

SDPSL-2019-063 Page 12 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max Bioaccumulative potential This preparation or material is not expected to bioaccumulate.

Other information no data available Section: 13. DISPOSAL CONSIDERATIONS If this product becomes a waste, it is not a hazardous waste as defined by the Resource Conservation and Recovery Act (RCRA) 40 CFR 261, since it does not have the characteristics of Subpart C, nor is it listed under Subpart D.

Disposal methods  : Where possible recycling is preferred to disposal or incineration. If recycling is not practicable, dispose of in compliance with local regulations. Dispose of wastes in an approved waste disposal facility.

Disposal considerations  : Dispose of as unused product. Empty containers should be taken to an approved waste handling site for recycling or disposal. Do not re-use empty containers.

Section: 14. TRANSPORT INFORMATION The shipper/consignor/sender is responsible to ensure that the packaging, labeling, and markings are in compliance with the selected mode of transport.

Land transport (DOT)

Proper shipping name  : PRODUCT IS NOT REGULATED DURING TRANSPORTATION Air transport (IATA)

Proper shipping name  : PRODUCT IS NOT REGULATED DURING TRANSPORTATION Sea transport (IMDG/IMO)

Proper shipping name  : PRODUCT IS NOT REGULATED DURING TRANSPORTATION Section: 15. REGULATORY INFORMATION EPCRA - Emergency Planning and Community Right-to-Know Act CERCLA Reportable Quantity This material does not contain any components with a CERCLA RQ.

SARA 304 Extremely Hazardous Substances Reportable Quantity This material does not contain any components with a section 304 EHS RQ.

SARA 311/312 Hazards  : Acute Health Hazard 7/9

SDPSL-2019-063 Page 13 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max SARA 302  : No chemicals in this material are subject to the reporting requirements of SARA Title III, Section 302.

SARA 313  : This material does not contain any chemical components with known CAS numbers that exceed the threshold (De Minimis) reporting levels established by SARA Title III, Section 313.

California Prop 65 This product does not contain any chemicals known to State of California to cause cancer, birth defects, or any other reproductive harm.

INTERNATIONAL CHEMICAL CONTROL LAWS :

AUSTRALIA All substances in this product comply with the National Industrial Chemicals Notification & Assessment Scheme (NICNAS).

CHINA All substances in this product comply with the Provisions on the Environmental Administration of New Chemical Substances and are listed on or exempt from the Inventory of Existing Chemical Substances China (IECSC).

JAPAN All substances in this product comply with the Law Regulating the Manufacture and Importation Of Chemical Substances and are listed on the Existing and New Chemical Substances list (ENCS).

KOREA All substances in this product comply with the Toxic Chemical Control Law (TCCL) and are listed on the Existing Chemicals List (ECL)

NEW ZEALAND All substances in this product comply with the Hazardous Substances and New Organisms (HSNO) Act 1996,and are listed on or are exempt from the New Zealand Inventory of Chemicals.

PHILIPPINES This product contains substance(s) which are not in compliance with the Republic Act 6969 (RA 6969) and may require additional review.

Section: 16. OTHER INFORMATION 8/9

SDPSL-2019-063 Page 14 SAFETY DATA SHEET Chlorine Dioxide Dissolved in water 4000 ppm max NFPA: HMIS III:

Flammability HEALTH 1 0

Health Instability 0 0 FLAMMABILITY 0 PHYSICAL HAZARD 0 0 = not significant, 1 =Slight, 2 = Moderate, 3 = High Special hazard. 4 = Extreme, * = Chronic Revision Date  : 03/16/2016 Version Number  : 0.0 Prepared By  : Regulatory Affairs REVISED INFORMATION: Significant changes to regulatory or health information for this revision is indicated by a bar in the left-hand margin of the SDS.

The information provided in this Safety Data Sheet is correct to the best of our knowledge, information and belief at the date of its publication. The information given is designed only as a guidance for safe handling, use, processing, storage, transportation, disposal and release and is not to be considered a warranty or quality specification. The information relates only to the specific material designated and may not be valid for such material used in combination with any other materials or in any process, unless specified in the text.

For additional copies of an SDS visit www.nalco.com and request access.

9/9

SDPSL-2019-063 Page 15 - Minor Permit Revision Application (2 Pages)

APPLICATION FOR A MINOR REVISION TO A WASTEWATERFACILITYORACTIVITY PERMIT

1. Instructions
a. In accordance with Rule 62-620.325, F.A.C., this form must be submitted to the appropriate Department district office or approved local program when requests for minor revisions to a permit or minor modifications to a facility are made by a permittee, except for transfer of a permit to a new permittee and addition of a major user of reclaimed water to a Part III reuse system. Application for transfer of a permit to a new permittee shall be made on DEP Form 62-620.910(11). Application for addition of a major user ofreclaimed water shall be made on DEP Form 62-610.300(4)(a)l.
b. Each applicable item must be completed in full in order to avoid delay in processing of this form. Where attached sheets or other technical documentation are provided, indicate appropriate cross-references.
c. Three (3) copies of this application with supporting documentation shall be submitted with this form.
d. All information is to be typed or printed in ink. Dates are to be entered in MM/DD/YR format.
e. This application and attachments shall be signed in accordance with Rule 62-620.305, F.A.C. Also, as applicable, this application and all attachments shall be signed and sealed by a professional engineer registered in Florida in accordance with Rule 62-620.310, F.A.C.
2. Facility Information
a. Permit Nmnber: FL0002208 ~~~~~~~~-
b. Facility Identification Number:
c. Project/Facility Name: Florida Power & Light St. Lucie Plant
d. Contact Name: Daniel DeBoer Nmnber and Street: 6501 South Ocean Drive City/State/Zip Code: Jensen Beach, FL 34957 Telephone 772-465-3550
3. Type of Revision D Correct Typographical Errors1 - Submit one copy of each page of the permit showing revisions being requested.

D Change Improvement Schedule1 - Provide a description of the improvement, a list of the dates to be revised, and a reason for the proposed change in each date.

D Change Expiration Date of Permit1 - Provide the current and proposed expiration dates for the permit and the reasons for the proposed change.

D Change Staffing Requirements2 - Describe the proposed change and submit justification for the change in accordance with Chapter 62-699, F.A.C.

1 A processing fee is not required. DEP Form 62-620.910(9) 2A processing fee is required with the application Effective October 23, 2000 in accordance with Rule 62-4.050, F.A.C.

D Change Monitoring and Reporting Requirements2 - Describe the proposed change and submit justification for the change in accordance with Chapter 62-601, F.A.C.

D Modify Approved Pretreatment Program1 - Describe the proposed modification and provide the information required by Rule 62-625.540, F.A.C.

D Delete Point Source Outfall1 - Identify the outfall and explain why the outfall is being eliminated.

D Modify or Expand Approved Residuals Land Application Sites2 - Attach a new or updated Agricultural Use or Dedicated Site Plan as required by Chapter 62-640, F.A.C.

~ Minor Modification to the Facility2 - Provide a description of the proposed modification. If applicable, attach any reports, plans, and specifications which have been developed to implement this modification.

D Other2 - Provide appropriate documentation. Describe.

4. Certifications
a. Applicant or Authorized Representative I certify under penalty of law that I have personally examined and am familiar with the information submitted in this application and all attachments and that, based on my inquiry of persons immediately responsible for obtaining the information contained in the application, I believe that the information is true, accurate and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment.

/)~()~~- ~_,_,_H~k~sJi~1q°"--~~~-

(Signature of Applicant or Authorized Representative3) (Date)

Name (please type) _D_a_ni_el_D_e_B_o_e_r_ _ _ _ _ _ _ Company Name Florida Power & Light Title Site Director Company Address: 6501 South Ocean Drive Phone: 772-465-3550 City/State/Zip Code: _34_9_5_7_ _ _ _ _ _ _ _ _ _ __

Email (optional): Daniel.DeBoer@fpl.com

b. Professional Engineer Registered in Florida I certify that the engineering features of this project have been (designed) (examined) by me and found to conform to engineering principles applicable to such projects. In my professional judgement, this facility, when properly constructed, operated, and maintained, will comply with all applicable statutes of the State of Florida and rules of the Department.

Name (please type): Diane H. Nguyen

=--'-----------

Florida Registration Number: _7~0~7~1~4_ _ _ _ _ __

Company Name: Florida Power & Light Company Address: 700 Universe Blvd City/State/Zip Code: Juno Beach. FL 33408 PhoneNumber: 561-694-3185 Email (optional): diane.nguyen@fpl.com 3If signed by the authorized representative, 2 DEP Form 62-620.910(9) attach a letter of authorization in accordance Effective October 23, 2000 Rule 62-620.305, F.A.C.

Retrieved from "https://kanterella.com/w/index.php?title=L-2019-206,_Environmental_Protection_Plan,_Minor_Permit_Revision_Request_for_Chlorine_Dioxide&oldid=2357497"