Information Notice No. 96-19: Failure of Tone Alert Radios to Activate When Receiving a Shortened Activation Signal

WASHINGTON, D.C.  20555-0001

April 2, 1996

                               RECEIVING A SHORTENED ACTIVATION SIGNAL


All holders of operating licenses or construction permits for nuclear power


The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees to the possibility that tone alert radios may not
reliably activate when receiving a shortened activation signal.  It is
expected that recipients will review the information for applicability to
their facilities and consider actions, as appropriate, to avoid similar
problems.  However, suggestions contained in this information notice are not
NRC requirements; therefore, no specific action or written response is

Description of Circumstances

In a report made pursuant to Section 50.72(b)(1)(v) of Title 10 of the Code of
Federal Regulations (10 CFR 50.72(b)(1)(v)), Event Number 29907, dated 
January 30, 1996, the licensee for the Callaway site reported a problem with
tone alert radios.  During a test of the Emergency Alert System (EAS), a radio
station engineer observed that a tone alert radio receiver did not activate. 
An investigation by the licensee found that the length of the broadcast
activation signal was insufficient to reliably activate the tone alert radio
receiver model in use at the radio station.  The broadcast duration of the
activation signal had been reduced from 20 seconds to 8 seconds as permitted
by current Federal Communications Commission (FCC) regulations.  The radio
station restored the duration of the activation signal broadcast to the
original 20-second length and observed that the tone alert radio receiver
activated as expected.  


Section 50.47(b)(5) of 10 CFR requires emergency response plans for nuclear
power reactors to include a means of providing early notification and clear
instruction to the populace within the plume exposure pathway emergency
planning zone (EPZ) in the event of an emergency.  Many nuclear power reactor
sites have integrated tone alert radios into alert and notification systems
used to notify and provide instructions to members of the general public near
the site during emergency situations.  

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These radios may serve as supplements to a siren system by filling in voids in
siren coverage, or they can be the principal means of notifying the EPZ
population.  Tone alert radio receivers are used in conjunction with the EAS.

On December 28, 1994, the FCC issued a Report and Order (59 FR 67090)
concerning the Emergency Broadcast System (EBS).  This Report and Order
replaced the EBS with what is now known as the EAS.  This change allowed for
the creation of a new generation of alerting equipment embracing digital
technology.  The change also modified some of the old EBS requirements.  One
of the changes permits the use of a shorter duration tone activation signal to
activate tone alert radio receivers.  This change may have decreased the
reliability of some tone alert radios currently in use to activate when

Before July 1, 1995, the broadcast duration of the signal that activates tone
alert radios was required to be between 20 and 25 seconds.  After July 1,
1995, the broadcast duration of the signal that activates tone alert radios
was permitted to be between 8 and 25 seconds.  The FCC encourages the use of
the longer (up to 25 seconds) tone during emergencies.

Tone alert radio receivers are, and have been, available from various
manufacturers for several years.  Depending on the specifications provided by
the purchaser, the threshold for activation has been built into receivers. 
The signal duration needed for some tone alert radio receiver models may be
longer than the currently approved 8-second minimum signal duration now
allowed by FCC regulations.

The FCC regulations permit individual radio stations to select the duration of
the activation signal they broadcast, provided it is within the limits of 8 to
25 seconds.  To reliably activate a tone alert radio receiver the duration of
the activation signal broadcast by the radio station must be long enough to
meet the activation threshold built into tone alert radio receivers in service
in a particular reception area.  If the duration of the activation signal
broadcast is not compatible with the threshold set in a receiver, the
reliability of the receiver response is questionable.  Either the duration of
the activation signal broadcast or the threshold for activation built into
receivers may need to be modified to ensure compatibility.
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This information notice requires no specific action or written response.  If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.

                                          signed by

                                        Dennis M. Crutchfield, Director
                                        Division of Reactor Project Management
                                        Office of Nuclear Reactor Regulation

Technical contacts:  D. M. Barss, NRR 
                     (301) 415-2922
                     J. L. Birmingham, NRR
                     (301) 415-2829

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