Presentation on theme: "ALARA and Radioactive Effluents Regulatory History and Application for Next Generation Power Reactor Licensing June 27, 2006 2006 RETS/REMP Workshop Presented."— Presentation transcript:
ALARA and Radioactive Effluents Regulatory History and Application for Next Generation Power Reactor Licensing June 27, 2006 2006 RETS/REMP Workshop Presented by: J. Stewart Bland, CHP Chesapeake Nuclear Services, Inc. Annapolis, MD 410-266-9174 email@example.com@chesnuc.com www.chesnuc.comwww.chesnuc.com
Objectives/Agenda Provide the history on the development (rulemaking) for 10 CFR 50, Appendix I; Describe the current regulatory requirements for radioactive effluents (e.g., the public exposure limits in 10 CFR 20 and 10 CFR 50, App I, and Regulatory Guide 1.109); Examine the concept of design basis for radioactive processing systems (10 CFR 50.34a) with implementation requirements (10 CFR 50.36a). Briefly describe regulatory approach and status of new plant licensing. Examine effect of implementing updated regulatory approaches and dosimetric modeling (ICRP 30 and ICRP 60/72) on Appendix I rule and plant implementation. Provide an overview of the NRCDose computer code (as time permits).
ALARA Rulemaking ALARA concept originally promulgated December 3, 1970 Rulemaking over next 4½ years, involving industry participation, hearings, NRC staff proposed rules. Final rule issued May 5, 1975. Rule required each light-water-cooled nuclear power plant to submit information necessary for evaluating compliance with rule by June 4, 1976.
10 CFR 50.34a Requirements Provides for the design basis for the plant. Description of design and equipment to be installed and used for the control of radioactive effluents, i.e., maintaining releases ALARA, including anticipated operational occurrences. Estimate of quantities of radioactive materials to be released annually. This design basis and ALARA demonstration is part of FSAR/USAR – Licensing basis for the plant.
10 CFR 50, Appendix A General Design Criteria GDC 60, “Control of Releases of Radioactive Materials to the Environment” –“... design shall include means to control suitable the release of radioactive materials in gaseous and liquid effluents and to handle solid radioactive waste produced during normal reactor operation, including anticipated operational occurrences. Sufficient holdup capacity shall be provided...” GDC 64, Monitoring Radioactivity Releases –“Means shall be provided for monitoring the reactor containment atmosphere,..., effluent discharge paths, and the plant environs for radioactivity that may be released from normal operations, including anticipated operational occurrences, and from postulated accidents.” USAR design must address these design criteria.
10 CFR 20 Requirements Applicable to Effluents 10 CFR 20.1301 with reference to 40 CFR 190 –Dose limit of 1 mSv (100 mrem) in a year, excluding background, medical, disposal in sewerage. –Dose in any unrestricted area from external sources shall not exceed 0.02 mSv/h (2 mrem/h). –If licensee permits members of public access to Controlled Areas, the 1 mSv limit continues to apply. –Licensees subjected to provisions of EPA’s 40 CFR 190 environmental dose standard. HPPOS-008 provides implementation guidance stating: RETS/ODCM methods acceptable for demonstrating compliance Assessment and reporting requirements included in Admin Section of TS 10 CFR 20.1302 – Compliance Methods –Licensee shall make appropriate surveys of radiation levels and radioactive material in effluents. –Annual average concentration of radioactive material released in effluents at the boundary of the unrestricted area does not exceed the values in Appendix B, Table 2 (EC values) 0.5 mSv/y (50 mrem/y) from continuous exposure; stochastic values only) 10 CFR 20.1101 – Exempts NPP licensees from the CAA 10 mrem/y constraint. 10 CFR 20.2203 – 30 day reporting if levels of radiation levels or releases of radioactive materials exceed 40 CFR 190.
10 CFR 50.36a Requirements Requires Technical Specifications for ensuring releases are maintained ALARA Explicit Requirements –Releases shall comply with 10 CFR 20.1301 (formerly 20.106) –Procedures shall be established and followed for operating radwaste treatment systems –Radwaste systems shall be maintained and used –Annual release reports shall be prepared and submitted to NRC. Guidance Requirements –Releases, on average, should be small fraction of 10 CFR 20.1301 limit –Best effort shall be exerted to keep releases ALARA –Appendix I provides numerical guidance on limiting conditions for operation for effluents
Appendix I Requirements Four design objectives - numerical dose values –Liquid effluents (per unit) 3 mrem/yr, total body 10 mrem/yr, any organ –Gaseous effluents (per unit) 10 mrad/yr, gamma air 20 mrad/yr, beta air 5 mrem/yr, total body (any real person) 15 mrem/yr, skin (any real person) –Airborne iodines and particulates (> 8 day T½, per unit) 15 mrem/yr, critical organ (real pathway) Doses (effluents) shall be further reduced as much as practical up to the expenditure of $1,000 per person-rem saved
Appendix I Limiting Conditions for Operation If releases during any calendar quarter exceed half the annual design objectives, licensee shall evaluate, correct, and report to NRC in 30 days. Surveillance program shall be established to monitor releases, monitor the environment and identify changes in land use.
RM-50-2 Annex to Appendix I Provides an alternative to Appendix I cost-benefit evaluation, based on licensee’s (and NRC’s) previous demonstrations with previous, interim requirements. Saved time and efforts based on licensee’s and NRC staff’s previous reviews performed during the rulemaking process. Applicable only for plants docketed after January 2, 1971 and prior to June 4, 1976 For Pre-1971 Plants –NRC performed study (NUREG-0389) documenting cost-benefit evaluation for those plants not covered by RM 50-2 alternative.
NRC’s Implementation Guidance Regulatory Guide 1.109, “Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I,” (Rev.1) October 1977 Regulatory Guide 1.110, “Cost-Benefit Analysis for Radwaste Systems for Light-Water-Cooled Nuclear Power Reactors,” March 1976 Regulatory Guide 1.111, “Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from Light- Water-Cooled Reactors,” (Rev. 1) July 1977 Regulatory Guide 1.112, “Calculation of Releases of Radioactive Materials in Gaseous and Liquid Effluents from Light-Water-Cooled Power Reactors,” April 1976 Regulatory Guide 1.113, “Estimating Aquatic Dispersion of Effluents from Accidental and Routine Reactor Releases for the Purpose of Implementing Appendix I,” (Rev. 1) April 1977
Implementation Schedule and Issues 10 CFR 50.34a and 50.36a promulgated in December 1970. Appendix I rule finalized and issued May 5, 1975. Required Licensees to submit information for evaluating compliance by June 4, 1976. First version of RETS issued 1978. Atomic Industrial Forum established Task Force to industry interface and negotiation with NRC on implementation. (See AIF letter dated 12/24/81: NRC & Industry Interface tab). Revised RETS issued 1979, included NUREG-0133 (ODCM) approach. (See Charlie Willis and Frank Congel presentation: NRC & Industry Interface tab). TMI happens – major delays in implementation of RETS at operating plants. RETS finally issued at all operating plants around 1984.
Industry/NRC Interface for Implementation Atomic Industrial Forum Task Force established to negotiate with NRC initial implementation – RETS development. –Reliance on current design as acceptable basis for most monitors and controls. –Eliminated requirement for P-32 sampling and analysis for liquid effluents. –Annual average met versus real-time; relaxation of requirement to use short-term met for purges. –Accepted current basis for monitor calibrations –Use of pump curves in lieu of flow rate monitors –Relaxed approach to TB sump monitors, composite samplers, tank recirc. (Refer to NRC/Industry Implementation section)
NRC’s RETS and ODCM Guidance NRC’s Initial Standard Radiological Effluent Technical Specifications (NUREG - 0472 and - 0473) NUREG-0133, “Preparation of Radiological Effluent Technical Specifications for Nuclear Power Plants,” October 1978 –keep details out of TS –presented methods acceptable to NRC –can be changed without NRC licensing action –subjected to after-the-fact NRC review (and passive approval) –alarm setpoint methodology –simplified dose calculations –guidance for other issues (atmospheric steam relief valves, outside tanks, etc.)
NRC’s RETS and ODCM Guidance (con’t) NRC Radiological Assessment Branch Technical Position, “Radiological Environmental Monitoring,” (Rev. 1) November 1979 (see NRC/Industry Implementation tab) –Types and locations for environmental monitoring –QA program: interlaboratory sample splitting program –Land-Use Census –Reporting format NRC’s Technical Specification Improvement Effort –NRC Generic Letter 89-01 –Encouraged licensees to revise to new format. –Many advantages with most requirements relocated to ODCM. –Licensee able to revise without NRC approval. NUREG - 1301 and - 1302 –NRC’s guidance on revised RETS/ODCM format. –Addresses 10 CFR 20 revision. –Supports current STS approach.
RETS Not Directly Required by Appendix I Safety Related Requirements –Control of explosive gas mixtures –Curie content of waste gas decay tanks –Activity in BWR main condenser off-gas –Curie limit for outside liquid storage tanks NRC Staff’s Interpretation and Application of ALARA –Radioactive material concentration in liquid effluents shall not exceed 10X EC (or MPC) at discharge point –Gaseous effluents shall not exceed dose rate of 500 mrem/yr, total body, 3000 mrem/yr, skin or 1500 mrem/yr, any organ –Radwaste systems shall be maintained and used to process effluents prior to release when projected doses exceed fraction of design objectives
Changes to Address 10 CFR 20 Revision Acceptable to continue to use old MPC values for controlling liquid release rate in lieu of new EC values (reference to old 10 CFR 20, Appendix B, Table II as opposed to current reference to current 10 CFR 20, Appendix B, Table 2). 10 times EC values allowed, which represents the same dose rate basis as MPCs - 500 mrem/yr. –Non-stochastic (organ) doses have not been considered, because these effects are not considered to occur at the member of the public dose limits. –For certain radionuclides, where the organ dose is much greater than the resultant EDE (e.g., I-131), 10 x EC will allow increases in maximum release rates. –For inhalation, ingestion, EC values were calculated by adjusting the occupational values, taking into consideration increased exposure and different dose criteria (50 mrem vs 5000 mrem). Also factor of 2 included to account for different age groups (other than adult worker).
Liquid and Gaseous Effluent – Design, Processing and Controls Primarily a licensing basis issue. NRC guidance: Standard Review Plan, NUREG-0800, Section 11. USAR design basis source term and processing controls basis for controls. June 4, 1976 Appendix I submittals Other licensing commitments. Provided releases maintained ALARA, predominantly a design basis issue. Operability: maintain and operate i/a/w design. Periodic verification of operability –Important if releases increase –Ability to handle off-normal conditions
NRC Bulletin 80-10 Title: “Contamination of Nonradioactive System and Resulting Potential for Unmonitored, Uncontrolled Release of Radioactivity to Environment” Issued in response to events at NPP where system use and operation inconsistent with design basis leading to inadequate controls over system contamination and releases. Required all NPP licensees: –To review system design/operation and institute a sampling and analysis program for potential unmonitored release points. –Establish controls and limits on non-radioactive systems if become contaminated. –Invoked 10CFR50.59 process to radioactive effluent controls.
Conducting Releases – Evaluations and Records Must be conducted i/a/w TS and ODCM (Advantages of Generic Letter 89-01 format) Must not be in conflict with UFSAR (50.59 process) Normal evaluated and control pathways (per design basis) Potential for releases from non-radioactive systems/pathways (NRC Bulletin 80-10) Records –ODCM dose calculations –Activities, volumes, time period Litigation Protection
Current Approaches to Pathway and Dose Modeling Reg Guide 1.109 and NUREG-0133 based on ICRP-2 dosimetric modeling (1950's data and critical organ approach). Age dependent dose factors developed for selected radionuclides. Revised 10 CFR 20 (1991) based on ICRP-26/30 dosimetric modeling and effective dose equivalent approach. Other Applicable Dose Standards –40 CFR 190, Environmental Dose Standard for Uranium Fuel Cycle (includes direct dose component): based on critical organ concept. –40 CFR 141, Drinking Water Standard [default concentration limits – mixed-bag ICRP-2 and ICRP-72 (FGR #13) considerations in a Dec. 7, 2000 final rule] –Clean Air Act: NRC licensees exempt –Decommissioning: ICRP-30 based, probabilistic modeling (DandD and RESRAD). Use of Updated Dosimetry - ICRP-60/72 (FGR #12 external): NRC has allowed use for certain decommissioning projects. Not codified.
Issues Surrounding New Plant Licensing and ALARA for Radioactive Effluents
Adapted from NEI March 2006 “Insight” Newsletter.
Steps in the Licensing Process Radwaste processing system design Evaluation of radioactive effluent source term Evaluation of compliance with Appendix I individual dose design objectives Cost-Benefit evaluation of radwaste system design -- $1000 per person-rem reduction NEPA evaluation Licensing hearings Development of Technical Specifications, ODCM, Radiation Monitoring Manual, Radiological Environmental Monitoring Manual
Overview of Regulatory Process Certified Designs: NRC can certify reactor design for 15 years through the rulemaking process. Certification process addresses safety issues of an essentially complete nuclear power plant design, independent of a specific site. –AP1000 - AP1000 Reactor by Westinghouse Electric CompanyAP1000 –ESBWR - Economic Simplified Boiling Water Reactor by General ElectricESBWR
Early Site Permit Application Reviews Clinton ESP Site - Exelon Generation Company, LLC ESP - Application submitted 9/25/03Clinton ESP Site Grand Gulf ESP Site - System Energy Resources Inc. ESP - Application submitted 10/21/03. NRC issued final EIS on 4/5/06, concluding no impacts that would prevent issuance of EISGrand Gulf ESP Site North Anna ESP Site - Dominion Nuclear North Anna, LLC ESP - Application submitted 9/25/03North Anna ESP Site
Combined Construction and Operating License (COL) Applications Several planned but no submittals to date. Radwaste system design and specifics for the radiation monitoring system likely will not be finalized in the COL submittals. This type information needed for NRC’s NEPA review and issuance of Environmental Impact Statement.
NRC Rule Changes Affecting ALARA for Effluents 10 CFR 20 –1991 revision Incorporated updated dosimetry – ICRP-30 100 mrem/y dose to public limit (effluent concentration limits based on 50 mrem/y liquid and 50 mrem/y atmospheric) –1997 revision for license termination (decommissioning) rule 10 CFR 20.1406, “Minimization of Contamination” (indirectly has potential impact because of plant design considerations)
10 CFR 20.1406 “Applicants for licenses, other than renewals, after August 20, 1997, shall describe in the application how facility design and procedures for operation will minimize, to the extent practicable, contamination of the facility and the environment, facilitate eventual decommissioning, and minimize, to the extent practicable, the generation of radioactive waste.”
NRC Rule Changes Affecting ALARA for Effluents (con’t) 10 CFR 50, §50.34a, §50.36a, and Appendix I –Essentially no fundamental changes in approach. –NRC proposed revisions to clarify (March 13, 2006, Federal Register Notice) applicability to design certification applications, combined construction and operating license applications and manufacturing license as covered in 10 CFR 52. Standard designs include radwaste system design information and calculations of radioactive effluents. Radioactive Source Term –NUREG-0016 (BWR-GALE code) and -0017 (PWR-GALE code) –Source term based on 1% or 0.1% failed fuel – needs clarification. Operating license applicants responsible for performing the site- specific dose analysis and final compliance with the Appendix I ALARA dose criteria.
New Plant Licensing Design Basis Considerations Standard designs include: –Design basis radwaste system 10 CFR 50.34a Reg Guide 1.143 design criteria Standard source term based on existing guidance GALE code [NUREG-0016 (BWR) and -0017 (PWR)] –10 CFR 50, GDC 60 -- Radioactive effluent monitors, but without specifics. Combined Construction/Operating License (COL) Application to include: –Radiation monitor setpoint methodology –Site-specific Appendix I compliance Site-specific pathway modeling and dose assessment –Cost-benefit analysis of radwaste system design ($1000 per person-rem population dose for additional radwaste processing capability) Plant specific ODCM, REMP, Radiation Monitoring Manual, and Radioactive Waste Process Control Program (PCP) to be submitted before fuel loading (Regulatory approach/position being developed)
Liquid Effluent Source Term Used for Evaluating Doses Based on ICRP-30/72 and RG 1.109 Dose Factors Nuclide Typical BWRTypical PWR (Ci/yr) 3H3H26280 24 Na1.60E-031.10E-03 54 Mn1.20E-033.90E-03 55 Fe2.90E-037.30E-03 59 Fe6.00E-052.20E-03 58 Co4.40E-038.30E-03 60 Co9.90E-031.40E-02 65 Zn5.40E-044.00E-05 89 Sr2.00E-041.00E-04 90 Sr2.00E-051.00E-05 131 I8.10E-024.60E-02 134 Cs1.30E-022.20E-02 137 Cs2.40E-023.00E-02 Based on generic release data from NUREG-0016 for BWR and NUREG-0017 for PWR.
NRCDose NRCDose is a user ‑ friendly 16-bit PC-based, software interface for the LADTAP II, GASPAR II, and XOQDOQ programs which operates under all Microsoft Windows TM platforms. LADTAP II, GASPAR II, and XOQDOQ are programs developed by NRC for implementing Regulatory Guides 1.109 and 1.111, which were originally created for mainframe computers and written using the FORTRAN programming language. These dose modeling codes are currently being used for license renewal evaluations. the NRC’s programs industry standards. While still utilizing the FORTRAN code, NRCDose incorporates a Windows TM based interface, which allows the user to enter and retrieve data through a series of windows. This graphical interface allows the user to create sets of data that can be named and retrieved at a later date for review or modification.
LADTAP LADTAP II implements the radiological exposure models described in Regulatory Guide 1.109, Rev. 1 for routine releases in liquid effluent. Calculates the radiation exposure to man from potable water, aquatic foods, shoreline deposits, swimming, boating, and irrigated foods, and also the dose to biota. Doses are calculated for both the maximum individual and for the population and are summarized for each pathway by age group and organ. Four different age groups are included in the dose assessments - infant, child, teen, and adult. LADTAP II also calculates doses to certain representative biota other than man in the aquatic environment such as fish, invertebrates, algae, muskrats, raccoons, herons, and ducks using models presented in WASH ‑ 1258. Reconcentration, if any, of each nuclide is determined from one of the three models (chosen by the user) available in the program, or the user may input the reconcentration factor if none of the models available in the program is appropriate. Available options include complete mixing, partial mixing, or the plug ‑ flow model. These models are described in US NRC Regulatory Guide 1.113.
ALARA Dose Analysis Drop-down menu offering choice of "Max Exposed Individual" and "Additional Usage Locations" data entry dialogs. The following describes data inputs relative to the presented menu items: –Max Exposed Individual... - presents the dialog for modification of the variables corresponding to Record Type 7 of the LADTAP input record. –To change the default usage and consumption data, click on the Yes option button in the Population Fractions frame and then click on the enabled Edit button. A dialog will be presented for editing.
Population Usage – Drinking Water, Shoreline, Swimming, and Boating Drop-down menu offering choice of "Drinking Water," "Shoreline," "Swimming," and "Boating." –Drinking Water... selection of the drinking water locations to be edited. Permits entry and modification of variables, which correspond to the Record Type 13 inputs. –Shoreline... - same as Drinking Water above, for Record Type 14 inputs. –Swimming... - same as Drinking Water above, for Record Type 15 inputs. –Boating... - same as Drinking Water above, for Record Type 16 inputs.
Irrigation Food Data Drop-down menu offering choice of "Pathway" and "Water Usage Locations" data entry dialogs. These inputs represent Records 17 and 18, which are treated as a data set –Pathway... selection of the food pathways to be edited. The data entry dialog permits entry modification of variables, which correspond to the Record Type 17 inputs. The bottom frame accommodates inputs for optional Record Types 17a. To change the default food consumption data, click on the Yes option button in the bottom frame and then click on the enabled Edit button. Click the Update button to accept the changes or the Cancel button to ignore any changes and return to the previous dialog. –Water Usage Locations... selection of the food pathways to be edited. Drop-down list box for selecting the food type. The data entry dialog presented permits entry modification of variables, which correspond to the Record Type 18 inputs.
Biota Exposures Dialog for selection of the biota locations to be edited. Doses calculated using simplistic modeling from BNWL-1754 –Data entry dialog permits entry modification of variables, corresponding to the Record Type 19 inputs. –Models biota uptake and simplistic dosimetry. –Doses to fish, invert., algae, muskrat, raccoon, heron, duck. –Better modeling available – DOE Guidance, RESRAD Biota.
GASPAR GASPAR implements the methodologies of Regulatory Guide 1.109, Rev. 1. Output from XOQDOQ is used as meteorological data input to GASPAR. The special locations are used for evaluating maximum-exposed individual doses and standard radial distances and segments are used for population doses. Seven exposure pathways are included within GASPAR - plume immersion, groundplane exposure, inhalation, vegetation, cow s milk, goat s milk, and meat. External exposure doses to the total body and skin are calculated for releases of noble gases using semi-infinite plume dose conversion factors coupled. Iodine and particulate releases are not included in direct exposure dose calculations. Similarly, groundplane, inhalation, and food pathways only consider radioiodine and particulate effluents. GASPAR is configured, with its input and output data and formats, mainly for performing plant design basis evaluations as needed for nuclear power plant licensing. However, it can be used for evaluating routine effluent releases with the input of source term and, as desired, meteorology specific to the time period of interest.
GASPAR -- Site Specifics Dialog for modifying the variables corresponding to Record Type 3 of the GASPAR input record. Change the presented default values as desired and press Update to accept the values or Cancel to ignore any changes, and return to the previous dialog. Average absolute humidity is for the growing season. If blank or zero, default of 8 g/m 3 is used. If an average temperature over growing season is input, humidity input should be the relative humidity.
GASPAR -- Population Data Dialog for modifying the variables corresponding to Record Types 4 and 4.1 of the GASPAR input record. –The "Title" is the only input for Record Type 4. –Variable IDAT is modified from this program. It is internally defaulted to "0," defining North as the starting compass center. –Click on the Data Entry... button to display either the dialog for entry of variables corresponding to Record Types 4.1.na and 4.1.nb, or that for entry of variables corresponding to Record Type 4.2. –The displayed dialog is dependent on the setting of variable KT in Record Type 4.1 (Input by distance and direction - if checked). –Data input values are the number of people in each sector or total 50-mile population.
Milk, Meat and Vegetable Data Milk Production Data... - similar to Population Data above, but relates to Record Type 5. Refer to the Population Data section for description. Meat Production Data... - similar to Population Data above, but relates to Record Type 6. Refer to the Population Data section for description. Vegetable Production Data... - similar to Population Data above, but relates to Record Type 7. Refer to the Population Data section for description. Data input values are in units of L/y (milk) and kg/y (meat and vegetables)
GASPAR -- Source Terms Multiple source terms can be specified for distinguishing between different release points (and different meteorology). Dialog for selection of the source term to be edited. Click on the desired source term to highlight it for modification of the variables corresponding to Record Types 8 and 8.1 of the GASPAR input record. The "Title" is the only input for Record Type 8. Click on the Edit button to display the dialog for modifying the source term values (Record Types 8.1.n). This dialog permits radionuclide information entry for up to 33 nuclides. Clicking on the NxPg or PrvPg command buttons will move to the next or previous page of nuclides.
Meteorological Data Meteorological Data - presents drop-down menu offering choice of "Undecayed, Undepleted," "Decayed, Undepleted," "Decayed, Depleted," or "Ground Deposition" data entry dialogs. Need entry for each Source Term. –Undecayed, Undepleted... - dialog for modifying the variables corresponding to Record Types 9 and 9.1 of the GASPAR input record. Click on the Data Entry... to display the dialog for entry of variables corresponding to Record Types 9.1.na and 9.1.nb. Data input units are sec per m 3. –Decayed, Undepleted... - similar to Undecayed, Undepleted above, but relates to Record Type 10. Units are sec per m 3. –Decayed, Depleted... - similar to Undecayed, Undepleted above, but relates to Record Type 11. Units are sec per m 3 –Ground Deposition... - similar to Undecayed, Undepleted above, but relates to Record Type 12. Units are m -2.
Meteorological Dispersion Parameters – Definitions and Use –Undecayed, Undepleted: Units are second per m 3. No decay during transit; no depletion of plume. –Decayed, Undepleted: Units are seconds per m 3. –Decayed, Depleted: Units are seconds per m 3 –Ground Deposition: Units are m -2.
XOQDOQ XOQDOQ designed for evaluating routine releases from nuclear power plants. Primarily designed to calculate annual average relative effluent concentrations (X/Q values) and annual average relative depositions (D/Q values) at user specified locations (for maximum exposed individual dose assessment) and at various standard radial distances and segments (for population dose assessment). Evaluation of meteorological dispersion for intermittent releases (e.g., containment purge or waste gas decay tank releases) may also be evaluated. Instead of the annual average, less frequent meteorological condition may be assumed. An interpolation is performed for correlating less frequent meteorological condition to the annual average conditions.
XOQDOQ (con’t) The meteorological modeling includes consideration of building wake effect, plume depletion due to dry deposition and radioactive decay. Up to three separate decay half-lives can be specified –Regulatory Guide 1.111 recommends the use of a 2.26 day half-life for short-lived noble gases and 8 day half-life for iodines. – Release height and plume rise can be modeled or the plume may be modeled as a ground level release. XOQDOQ can also utilize a so-called “mixed mode” release, where, under certain meteorological conditions, the release is treated as elevated and, under other conditions, as ground level. The combination of these two conditions produces the annual average conditions.
XOQDOQ (con’t) The release may be treated as always elevated, always ground level, or a mixed mode, which is primarily used in the analysis of vent release points at or above the height of adjacent structures. The effluent plume for elevated releases can undergo plume rise due to momentum and/or buoyancy. Ground-level releases can be affected by additional dispersion due to nearby building wakes. Wind speeds measured at one level may be extrapolated to other elevations for release point evaluation. Plume growth parameters (σy and σz) can be described by Pasquill-Gifford curves or desert curves by Markee. For elevated releases, topography can be inputted for use in calculation of the effective plume height. The plume may undergo radioactive decay for varied half-lives. The plume may be depleted via dry deposition.
XOQDOQ (con’t) X/Q and D/Q values may be modified by standard or inputted values to account for local air recirculation or air stagnation. X/Q and D/Q values can be evaluated for predetermined distance segments and for specified points of interest. The joint frequency data may be inputted as a percent frequency of occurrence or as a total frequency of occurrence. The wind direction is broken down into the standard sixteen (16) 22.5 sectors (e.g., N, NNE, NE, ENE, etc.). Up to fourteen (14) separate wind speed classes can be modeled and the atmospheric stability is grouped according to seven (7) categories from extremely unstable (A class) to extremely stable (G class). The output from XOQDOQ may be modified, which will allow its direct use as an input meteorological data set for the GASPAR code. An example XOQDOQ computer run output, appropriately modified, is presented in Attachment 1.
XOQDOQ Variables Variables menu option presents a drop-down menu offering "Options," "Parameters," and "Wind Data" selections. Options... - presents the dialog shown for modifying the variables corresponding to Record Type 1 of the XOQDOQ input record. KOPT(11), which calculated using 30 o sectors is not changeable from within this program. It is defaulted to "0." If first option is checked [KOPT(1) = 1], remember to add 1 to NVEL (number of velocity categories), first input in System Parameters dialog box. Third option [KOPT(3)], option to compute sector spread for comparison to centerline value in purge calculations is not currently operable.
XOQDOQ -- Parameters Parameters... -dialog for modifying the variables corresponding to Record Type 3 of the XOQDOQ input record.
XOQDOQ – Parameters (con’t) NDIS variable (number of distances with terrain data for each sector) if greater than "0" enables the associated Heights button. Clicking on this Heights button displays the dialog for entry/modification of variables corresponding to Record Types 10 and 11.
XOQDOQ – Parameters (con’t) NPTYPE variable (number of titles of receptor types) if greater than "0" enables the associated Define button. Clicking on this Define button displays dialog for entering or modifying variables corresponding to Record Types 13 and 12. Filling in a Title enables the adjacent text box for entry of the number of locations (NPOINT), which in turn if greater than "0" enables the associated Define button. Clicking on this Define button displays the dialog for entering or modifying variables corresponding to Record Type 14.
XOQDOQ – Parameters (con’t) NEXIT variable (number of release exit points) if greater than "0" enables the associated Define button. Clicking on this Define button displays dialog for editing release point information. Click on the desired release point ID and then click on Edit to display that permits entering and modifying variables which correspond to Record Types 15 and 16. Click on the More button to enter or modify variables which correspond to Record Types 17. NCOR variable (number of distances of site specific correction factors for recirculation) if greater than "0" enables the associated Corrections button. Clicking on this Corrections button displays a dialog for entry/modification of variables corresponding to Record Types 8 and 9.
XOQDOQ – Parameters (con’t) UCOR (wind speed class correction factor) is part of Record Type 7. Clicking on the adjacent Speed Limits button displays for entering or modifying the remaining variables corresponding to Record Type 7. –If KOPT(1) = 1 (option set), calms are a distinct wind velocity class and appropriate input is required. –If the wind speed classes are defined in units of miles per hour, the wind speed class correction factor (UCOR) must be a value greater than 100 (use 101) to convert inputs to meters per second.
XOQDOQ -- Wind Data Wind Data… presents another drop-down menu offering choice of "Misc Parameters," "Calms Data," and "Joint Freq Data" data entry dialogs. –Misc Parameters... - presents the dialog for modifying location of the variables corresponding to Record Type 4 of the XOQDOQ input record. –Calms Data... - presents the dialog for modifying the variables corresponding to Record Type 5 of the XOQDOQ input record. –Joint Freq Data... - presents the dialog for modifying the variables corresponding to Record Type 6 of the XOQDOQ input record.
Joint Freq Data Input Joint Freq Data... - presents the dialog for modifying the variables corresponding to Record Type 6 of the XOQDOQ input record.