NUREG/CR-3488, Forwards Vol 3 of NUREG/CR-3488, Comparison of Trajectories,Tracer Concentration Patterns & Mesodif Model Calculations, Provided Under FIN B-5690 Re Atmospheric Dispersion Experiments.Research Summary Also Encl.W/O Rept
| ML20207F379 | |
| Person / Time | |
|---|---|
| Issue date: | 03/20/1985 |
| From: | Kornasiewicz R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Congel F, Gammill W, Hulman L Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20207F378 | List: |
| References | |
| CON-FIN-B-5690, FOIA-86-849, RTR-NUREG-CR-3488 NUDOCS 8701060002 | |
| Download: ML20207F379 (4) | |
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g a j WASHINGTON, D. C. 20555 l 2 !
. MAR 2 01985 l
MEMORANDUM FOR: Those on Attached List FROM: Robert A. Kornasiewicz, Leader Hydrology Section Earth Sciences Branch Division of Radiation Programs &
Earth Sciences, RES
SUBJECT:
TRANSMITTAL OF NUREG/CR-3488, IDAHO FIELD EXPERIMENT, 1981 VOL. 3 : " COMPARISON OF TRAJECTORIES, TRACER CONCENTRATION PATTERNS AND MES0DIF MODEL CALCULATIONS" The enclosed subject report is provided under FIN B5690, Atmospheric Dispersion Experiments. A copy of the Research Sumary of this report is enclosed.
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Robert A. Kornasiewicz, Leader
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Hydrology Section
. Earth Sciences Branch Division of Radiation Programs &
Earth Sciences, RES
Enclosures:
- 1. NUREG/CR-3488 Vol. 3
- 2. Research Sumary 1
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Addressees--Memorandum (w/ encl) dated R 2 0 585 subject: Transmittal of NUREG/CR-3488, Vol. 3 F. Congel, NRR, P-712 W. Ganmill, NRR, P-730 L. Hulman, NRR, P-822 D. Matthews, IE, EWW-359 P. McKee, IE, EWS-346 K. Perkins, IE, 3302 A. Thadani, NRR, 216 I. Spickler, NRR, P-730 J. Martin, RES,1130-SS M. Solberg, IE, EWS-346 B. Zalcman, IE, 3302 I
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4 RESEARCH
SUMMARY
REPORT TITLE: Idaho Field Experiment, 1981 Volume 3: Comparison of Trajectories, Tracer Concentration Patterns and ME50DIF Model Calculations AUTHORS: G. E. Start, J. H. Cate, J. F. Sagendorf, G. R. Ackerman, C. R. Dickson, N. H. Nukari, and L. G. Thorngren PROJECT TITLE: Atmospheric Dispersion Experiments FIN: B5690 NRC PROJECT MANAGER: Robert A. Kornasiewicz CONTRACTOR: National Oceanic and Atmospheric Administration PRINCIPAL INVESTIGATOR: G. E. Start REGULATORY CONTEXT: Section 50.47 of 10 CFR Part 50 establishes standards that
- must be met by the onsite and offsite emergency response plans in order for the staff to make a positive finding that there is reasonable assurance that adequate protective measures can and will be taken in the event of a radiological emergency. Included in these standards is paragraph 50.47(b)(9) which specifies that " Adequate methods, systems and equipment for assessing and monitoring actual or potential offsite consequences of a radiological emergency condition are in use." Appendix E of 10 CFR Part 50 further cites in this context specific criteria in NUREG-0654; FEMA-REP-1 which include a dose projection capability, utilizing atmospheric dispersion models, for the plume exposure pathway within the EPZ.
RESEARCH OBJECTIVES: The objective of this study was to utilize data from a series of field tests in which tracer gas (sulfer hexafluoride SF ) was released into the atmosphere and the resulting concentrations measu, red, to evaluate the performance of the MESODIF atmospheric dispersion model under a variety of meteorological conditions. A comparison was also made of the trajectory of the tracer gas plume with measured air flow patterns to determine ,
the effects of air flows on tracer concentration configurations. '
i RESEARCH FINDINGS OR RESULTS: Quantitative comparisons, based on MES0DIF i modeled trajectories, show that about 40% of the area impacted by SF ggaseous tracer is calculated to be impacted by MESODIF modeled tracer behavicrs. For the small grid, 94% of the calculated areas correspond to observed impact areas. For the large grid this percentage is about 80%. The concentration )
impact comparisons closely parallel the findings for transport and trajectories. Calculated total impacts account for about 2/3 of the observed i l
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total impacts. Large and small grid impacts are 66 and 69% of the observed amounts when each type is pooled for all tects. 1 The difference in these average percentages is probably not statistically significant. For the large grid, 86% of the calculated impacts are coincident with observed impacts; for the small grid 94% are coincident.
Qualitative investigations suggest that transport into the six characteristic zones of tracer impact are correctly identified about 75% of the time by using either MES0DIF calculated trajectories or tetroon marked trajectories. If both trajectory types are pooled together, the percentage of correctly identified zones increases to 83%.
The timing (the WHEN consideration) for impact occurrences has not been investigated. The basic questions of where impacts occurred and how much impact occurred have been addressed. In both instances the calculated area coverages and the total impacts are biased toward being too small compared to observations.
REGULATORY IMPLICATIONS: Based on information from this particular series of field tests, the following recomendations are made concerning the MES0DIF model:
The MES0DIF model should be reviewed for possible modification following these comparisons. While MES0DIF had success in describing plume transport and diffusion, there seems to be systematic bias toward under calculation of both area of coverage and sums of concentrations. Model calculation sensitivities to inclusion of vertical shear of wind direction and alternate plume mass distributions should be investigated.
The information developed by this study can be used in support of NRC staff reviews of licensee / applicant emergency response accident assessment capabilities, as well as in the selection or use of models that may be installed at the NRC Operations Center.
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EARTH SCIENCES BRANCH ..
METEOROLOGY / HYDROLOGY PROGRAM REGULATORY IIEEDS TO BE ADDRESSED .
FLOOD PROBABILITY DEVELOPMENT OF A METHODOLOGY FOR MAKING REASONABLE AND BELIEVABLE FLOOD PROBABILITY ESTIMATES TO DEVELOP FLOOD HAZARD CURVES USEABLE IN PRA'S. NEEDED BY NRR STAFF TO REPLACE AN INTERIM PROCEDURE USING DEFAULT VALUES THAT CURRENTLY MUST BE UTILIZED.
RADIONUCLIDE DISPERSION ANALYSES o EVALUATION OF DISPERSION MODELS TO DETERMINE WHICH ARE MOST AP-PLICABLE FOR USE IN CHARACTERIZING THE AIRBORNE PLUME WITHIN THE EPZ, ITCLUDING UNCERTAINTIES AND DATA FEQUIREMENTS. INFORMATION IS NEEDED BY NRR S IE STAFFS IN LICENSING DECISIONS CONCERNING THE ADEQUACY OF MODELS FOR EMERGENCY RESPONSE APPLICATIONS AND BY RES AS BASIS FOR DEVELOPING REGULATORY GUIDANCE ON REAL-TIME DISPERSION MODELS.
o EVALUATION OF METHODOLOGIES USED TO ASSESS PLUME RISE TO DETER-MINE WHICH ARE APPLICABLE TO NUCLEAR FACILITIES, INCLUDING SEVERE ACCIDENT AND FIRE SITUATIONS. NEEDED TO DECREASE RISK UNCERTAIN-TY RANGES IN NRR STAFF ACCIDENT ANALYSES STATEMENTS.
o DETERMINATION OF WASHOUT COEFFICIENTS FOR RELEASED, WATER-SOLUABLE AND PARTICULATE FISSION PRODUCTS DURING RAINFALL, WHICH ARE CURR-ENTLY CONTROVERSIAL. NEEDED TO DECREASE RISK UNCERTAINTY RANGES IN NRR STAFF ACCIDENT ANALYSES STATEMENTS.
TORNADO RISK ASSESSMENT INVESTIGATION OF THE LEVELS OF UNCERTAINTY IN CURRENT. TORNADO WIND SPEED ESTIMATES, AND CALIBRATIONS OF STRUCTURAL DAMAGE TO INTERRED WIND SPEEDS. NEEDED BY NRR STAFF TO REDUCE UNCERTAINTIES IN PRA'S -
CONCERNING PLANT DAMAGE DUE TO HIGH WINDS, INCLUDING THOSE FOR OP-ERATING REACTORS.
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HYDROLOGY & METEOROLOGY RESEARCH PROGRAMS Meteorology Validation of dispersion and plume rise models Confirmation of washout coef-ficients for dry plumes impacted by rainfall Quantification of error bands on tornado hazard curves Realistic dispersion models for non-neutrally bouyant gases and aerosols Hydrology Relationships between flood probability and determinis-tic data Ground water monitoring tech-niques fo'r tank releases and pool seepage at NPPs l
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