Information Notice No. 84-91: Quality Control Problems of Meteorological Measurements Programs

                                                             SSINS:  6835  
                                                             IN 84-91      

                               UNITED STATES 
                            WASHINGTON, DC 20555 

                             December 10, 1984 

Information Notice No. 84-91:   QUALITY CONTROL PROBLEMS OF 
                                   METEOROLOGICAL MEASUREMENTS PROGRAMS 


All nuclear power reactor facilities holding an operating license (OL) or a 
construction permit (CP). 

Purpose and Summary: 

This information notice is provided to inform licensees of ongoing problems 
with the collection of important meteorological data at nuclear power 
reactors. It was found that some meteorological measurements programs have 
not been properly operated and maintained to ensure the availability of 
high-quality meteorological data for use in emergency response and in 
assessments of the radiological impacts of routine and "off-normal" releases
to the atmosphere. It is expected that recipients will review the 
information for applicability to their facilities and consider actions, if 
appropriate, to preclude a similar problem occurring at their facilities. 
However, suggestions contained in this information notice do not constitute 
NRC requirements; therefore, no specific action or written response is 

Description of Circumstances: 

Poor quality meteorological measurements resulting from inadequately 
operated and maintained meteorological programs have been encountered and 
identified through emergency preparedness appraisals, Licensee Event Reports 
(LERs), and reviews of meteorological data summaries submitted in semiannual 
effluent reports. 

There are two major concerns in this area. One concern is the availability 
of sufficient meteorological data; the second is the availability of valid 
meteorological data. 

For example, one licensee claimed achievement of about 90% availability for 
meteorological data; however, only about 50% of those data were within 
accuracy specifications. A number of licensees have experienced frequent and
often prolonged outages of the data collection systems, due to severe 
weather such as lightning, icing, and high winds, with loss of significant 
amounts of data.  Other licensees have experienced gradual degradation 
and/or frequent 


                                                      IN 84-91            
                                                      December 10,  1984  
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replacement of meteorological sensors due to local environmental conditions 
such as salt, dust (including coal dust), or the synergistic effects of 
pollutants such as sulfur oxides and nitrogen oxides with moisture. 
Misalignment of wind direction sensors and problems with measurement of 
vertical temperature difference (through failure of the aspirator or 
orientation of the shield) have also been reported by licensees. Inadequate 
maintenance and control of ground cover and tree growth that may obstruct 
air movement in the vicinity of the meteorological measurement system 
(resulting in erroneous wind speed, wind direction, and atmospheric 
stability determinations) have been observed during NRC inspections. 


During emergency response situations, availability of erroneous 
meteorological data could result in mis-characterization of important 
conditions such as wind speed (for determining plume arrival and transit 
times), wind direction (for determining plume position), and atmospheric 
stability (for determining the concentration of material within the plume 
and plume shape). The mis-characterization of meteorological conditions 
could adversely affect: recommendations for protective actions (e.g., 
evacuation vs. sheltering); designation of the area for which actions are 
warranted; assessments of plume arrival and transit times; and deployment of
environmental sampling teams. For assessments of "non-accident" releases, 
erroneous meteorological data may result in an improper calculation of dose,
thereby making the demonstration of continuing compliance with the numerical
dose guidelines of 10 CFR 50, Appendix I, suspect. For example, 
mis-characterization of atmospheric stability by one class can result in a 
difference of a factor of 10 in estimates of short-term concentrations. 

A number of data screening and checking programs are available for use with 
computerized data collection systems. Such programs used by the NRC staff 
are described in NUREG-0917, "Nuclear Regulatory Commission Staff Computer 
Programs for Use with Meteorological Data," published in July 1982. For 
non-computerized data collection systems, such as those recording directly 
on strip charts, data screening and checking requires special skills to 
identify subtle variations in data trends and ranges. Data screening and 
checking programs and procedures can supplement regular operability, 
maintenance, and calibration checks. 


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                                                      December 10, 1984   
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No specific action or written response is required by this information 
notice. If you have any questions about this matter, please contact the 
Regional Administrator of the appropriate NRC Regional Office or this 

                                   Edward L. Jordan, Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contacts: James E. Fairobent, NRR  

                    William L. Fisher, IE  

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