United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 91-60: False Alarms of Alarm Ratemeters Because of Radiofrequency Interference

                                  UNITED STATES
                          NUCLEAR REGULATORY COMMISSION
                OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS
                             WASHINGTON, D.C. 20555 

                               September 24, 1991


NRC INFORMATION NOTICE 91-60:   FALSE ALARMS OF ALARM RATEMETERS
                                BECAUSE OF RADIOFREQUENCY INTERFERENCE 


Addressees 

All Nuclear Regulatory Commission (NRC) licensees authorized to use sealed 
sources for industrial radiography. 

Purpose

This information notice is being issued to alert licensees to recently 
reported false alarms of alarm ratemeters.  These false alarms reportedly 
occurred when the alarm ratemeters were exposed to radiofrequency 
interference (RFI) originating from different sources, including a variety 
of radar, welding machines, and hand-held radios.  Except for permanent 
radiography facilities where other appropriate alarming or warning devices 
are in routine use, radiography personnel are required, by 10 CFR 34.33, to 
wear an alarm ratemeter when performing radiographic operations.  It is 
expected that licensees will review this notice, distribute it to 
responsible staff, and consider actions, as appropriate, to avoid similar 
problems.  However, suggestions contained in this information notice do not 
constitute any new NRC requirements, and no written response is required. 

Description of Circumstances

An NRC licensee recently advised NRC of incidents in which alarm ratemeters 
alarmed because of apparent RFI, not because of ionizing radiation levels 
exceeding background.  In one instance, alarm ratemeters worn by radiography 
personnel began to continuously alarm as the individuals climbed onto an 
open deck of a ship on their way to a work site.   No radiographic 
operations were being conducted in the area.  The individuals immediately 
surveyed their radiography equipment with their radiation survey instruments 
and did not detect high radiation levels.

The individuals' self-reading dosimeters also showed no apparent radiation 
exposure.  Licensee investigation determined that the likely source was 
either shipboard radar or other RFI emitters.  The licensee also reported 
that there had been several other instances of false alarms that occurred 
when alarm ratemeters were located:  (1) within 20 feet of hand-held two-way 
radios operating at frequencies around 800 megahertz (MHz); (2) within 1 
foot of portable radios operating on frequencies ranging upward from about 
130 MHz; (3) near welding machines; (4) in the vicinity of various radar 
systems; and (5) near various pieces of electronic office equipment. 
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                                                       IN 91-60 
                                                       September 24, 1991 
                                                       Page 2 of 3 


One alarm ratemeter manufacturer indicated to NRC that other users have also 
reported RFI induced false alarms.  These reports all appear to involve the 
same ratemeter model.  This manufacturer also reported that several returned 
alarm ratemeters appeared to have been purposely damaged by users in an 
effort to defeat the devices.  

Several manufacturers are already aware of the effects of RFI on alarm 
ratemeters and are in the process of correcting the problem.  Licensees who 
have questions concerning their alarm ratemeter's susceptibility to RFI 
should contact the manufacturer directly. 

Discussion

Licensee personnel should be instructed to be aware of the possible presence
of RFI sources, such as two-way radios, that may interfere with radiation 
detection and measurement equipment, including alarm ratemeters.  Such RFI 
sources may be found at temporary job sites such as construction sites, 
shipyards, and aviation facilities.  

Licensees should also familiarize themselves and their radiography personnel 
with other operating aspects of their alarm ratemeters so that they may 
recognize false alarms that could result from depleted batteries, a device 
malfunction, or other conditions. 

Radiography personnel should be provided with guidance to be followed in 
case an alarm ratemeter alarms.  It is essential that radiography personnel 
avoid complacency about false alarms, regard all alarms as the result of 
elevated radiation exposure levels, and act accordingly until they are able 
to assure themselves, through radiation surveys and examination of 
self-reading dosimeters, that the alarm is not caused by ionizing radiation. 

The manufacturer's report of possible intentional damage to alarm ratemeters
is of concern to NRC.  Intentionally damaging and then using the damaged 
device when performing radiographic operations will be viewed as a willful 
violation of NRC regulations and considered for appropriate enforcement 
action, including civil penalties; license modification, suspension, or 
revocation; or orders to remove individuals from licensed operations. 

Licensees are reminded that the recent amendment to 10 CFR 34.33 (effective 
January 10, 1991) requires that radiography personnel use alarm ratemeters 
that alarm at a preset dose rate of 500 mR/hr.  This amendment also 
specifies that ratemeters must be checked before use, to ensure that the 
alarm properly functions (sounds). 

Although the use of alarm ratemeters will help to alert personnel to 
possible hazardous radiation levels, it is important that licensees 
emphasize to radiography personnel that alarm ratemeters are NOT intended to 
replace the use of survey meters or the performance of thorough radiation 
surveys during industrial radiography operations.  As was recently discussed 
in Information Notice No. 91-23, significant consequences, including 
serious bodily injuries or death, may result from the failure to perform 
adequate radiation surveys and properly handle industrial radiography 
equipment.  Licensees are also reminded 
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                                                       IN 91-60 
                                                       September 24, 1991 
                                                       Page 3 of 3 


that failure to have present, or to use, radiographic equipment, radiation 
survey instruments, and/or personnel monitoring devices, as required by 10 
CFR Part 34, will be cited as Severity Level III violations and may lead to 
civil penalties.  NRC's enforcement policy in this area is further discussed 
in NRC Information Notice 91-49, "Enforcement of Safety Requirements for 
Radiographers." 

No written response is required by this information notice.  If you have any 
questions about this matter, please contact the appropriate Regional Office 
or this Office. 




                                   Richard E. Cunningham, Director
                                   Division of Industrial and 
                                     Medical Nuclear Safety 
                                   Office of Nuclear Material Safety 
                                     and Safeguards 


Technical contacts: Torre Taylor, NMSS
                    301-492-0611

                    John M. Pelchat, Region II
                    404-331-5083


Attachments: 
1.  List of Recent NMSS Information Notices 
2.  List of Recent NRC Information Notices 

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