United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 79-18: Audibility Problems Encountered on Evacuation of Personnel from High-Noise Areas

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                           WASHINGTON, D.C. 20555 

                              August 7, 1979  

                                                  IE Bulletin No. 79-18 

AUDIBILITY PROBLEMS ENCOUNTERED ON EVACUATION OF PERSONNEL FROM HIGH-NOISE 
AREAS 

Description of Circumstances: 

In January 1979, a number of licensee personnel were engaged in routine 
activities in the auxiliary building at the Florida Power Corporation, 
Crystal River Unit 3 nuclear plant. While these individuals were working in 
the auxiliary building, in a high-noise (fan) area, an unplanned release of 
radioactive noble gases was detected by building monitors within the 
auxiliary building at concentrations which caused the licensee to initiate 
the facility emergency plan auxiliary building evacuation procedure. The 
facility Emergency Officer (Shift Supervisor) assessed the monitor readings 
and initiated an auxiliary building evacuation. The evacuation announcement,
made over the licensee's PA system, was not heard by the personnel working 
in the high-noise area. Licensee personnel did evacuate the auxiliary 
building upon observing that other personnel had left, and after calling the
control room to inquire if an evacuation had been initiated. During these 
occurrences, licensee personnel were not exposed to quantities of 
radionuclides above regulatory guidance. However, the potential existed for 
inadvertent unnecessary exposure of individuals to radioactive materials. 

Subsequent to the NRC followup inspection of this occurrence, Florida Power 
Corporation initiated an assessment of this situation and performed an 
engineering evaluation and identified several plant areas where the 
annunciator system needed audibility improvement. The licensee has installed
a new auxiliary building evacuation tone signal and may add visual alarm 
indicators in areas of very high noise. 

Action to be Taken by the Licensees: 

For all power reactor facilities with an operating license: 

1.   Determine whether current alarm systems and evacuation announcement 
     systems are clearly audible or visible throughout all plant areas with 
     emphasis on high-noise areas. Determination in high-noise areas must be
     made with the maximum anticipated noise level. 

2.   Determine what corrective action is necessary to assure that areas 
     identified as inaudible areas in (1) above, will receive adequate 
     audible/ 
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IE Bulletin No. 79-18                                       August 7, 1979 
                                                            Page 2 of 2 

     visual evacuation signals. In areas where adequate audible/visual 
     evacuation signals cannot be assured by hardware changes, determine 
     what additional administrative measures are necessary to assure 
     personnel evacuation. 

3.   Submit within 45 days of the date of issuance of this Bulletin, a 
     written report of the findings on item (1), and delineate completed or 
     proposed corrective actions per item (2). For operating facilities in 
     a refueling or extended outage, the written report must be submitted 
     within 30 days after plant startup following the outage. 

4.   For accessible areas, all corrective actions determined per item (2) 
     must be completed within 120 days of the date of issuance of this 
     Bulletin.  For inaccessible areas, the written report must include a 
     time schedule for completion of corrective actions in this area. 

Reports should be submitted to the Director of the appropriate NRC Regional 
Office and a copy should be forwarded to the NRC Office of Inspection and 
Enforcement, Division of Reactor Operations Inspection, Washington, D.C. 
20555. 

For all power reactor facilities with a construction permit, this Bulletin 
is for information only and no written response is required. 

Approved by GAO, B180225 (R0072); clearance expires 7/31/80. Approval was 
given under a blanket clearance specifically for identified generic 
problems. 

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