Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS: 6835
IN 84-91
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, DC 20555
December 10, 1984
Information Notice No. 84-91: QUALITY CONTROL PROBLEMS OF
METEOROLOGICAL MEASUREMENTS PROGRAMS
Addressees:
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
required.
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
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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.
Discussion:
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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IN 84-91
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
office.
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contacts: James E. Fairobent, NRR
(301-492-9427
William L. Fisher, IE
(301-492-4671
Attachment: List of Recently Issued IE Information Notices
