View source for PNO-III-88-034, on 880406,up to 68 Workers Received Minor Exposures to Airborne Radioactivity,Principally I-131,during Steam Generator Tube Plugging Activities.Cause Under Investigation.Respirators Required to Enter Containment

{{Adams
| number = ML20151C818
| issue date = 04/07/1988
| title = PNO-III-88-034:on 880406,up to 68 Workers Received Minor Exposures to Airborne Radioactivity,Principally I-131,during Steam Generator Tube Plugging Activities.Cause Under Investigation.Respirators Required to Enter Containment
| author name = Greger R, Shafer W
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION III)
| addressee name = 
| addressee affiliation = 
| docket = 05000454
| license number = 
| contact person = 
| document report number = PNO-III-88-034, PNO-III-88-34, NUDOCS 8804130197
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 2
}}
{{#Wiki_filter:PRElstMIMARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-88-34 Date April 7,1968
               .]    ,
This ' preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III                   ,
staff on this date.
Facility: Comonwealth Edison Company               Licensee Emergency Classification:              ,
Byron Unit 1                                 Notification of an Unusual Event         -
Byron, IL 61010                              Alert Site Area Emergency Docket No. 50-454                            General Emergency X Not Applicable                     l

==Subject:==
UP TO 68 WORKERS RECEIVE POSSIBLE MINOR AIRBORNE EXPOSURES                       fs During steam generator tube plugging activities on April 6, 1988, as many as 68 workers received minor exposures to airborne radioactivity, principally iodine-131. The exposures were a small fraction of NRC limits.
fnitially workers were found to have small internal depositions of iodine-131 after they triggered contamination monitors as they left the Unit 1 containment at 10:30 a.m. Control room operators had also observed slowly increasing iodine levels in the Unit 1 containment, but the levels were attributed to the recently opened steam generator. Unit I was shut down l  on April 3,1988, to repair a steam generator tube leak.                                            ,
t The containment was then evacuated at 11:46 a.m. because of suspected airborne radioactivity.
The licensee determined the source of the airborne iodine to be a temporary ventilation system for the steam generator manway. The ventilation airflow passed through a HEPA filter, but was discharged to the containment before it passed through the system's charcoal filter. The licensee is still investigating the cause of the ventilation system problem.
According to the licensee, 68 individuals were potentially exposed to the airborne iodine.
Uhole body counts have been performed on 36 persons to determine the level of iodine uptake, i
and the remaining individuals will be tested. The highest internal deposition measured j indicates an iodine uptake level of approximately 14 MPC-hours or about 2% of the regulatory
] limit.
; The licensee is restricting access to radiological areas for those indiviouals with greater than 1 percent MPC. All personnel entering the containment are wearing respirators with l charcoal cartridges until decontamination efforts are completed.
a 1
DISTRIBUTION:
,    H. St.                NMBB             Phillips        E/W         WFN 1
 ' Chairman Zech           AEUU             NRR             DTA         NP3r Com. Roberts          ARM                              OI          SLITP
 . Com. Bernthal           EDO                                          Mail To:
Com. Carr             PA        Resident Inspector Offices         DCS (Original)
Comm. Rogers          OGC           Resident Inspector             DOT (Trans. Only) 4 SECY                                                                               ,             A' i OGC-H                   FAX T0:          Nicholson Lane              Regions 4 CA                       INPO A:          RE5                         Region I               dp.
j GPA                    NSAC 4:o                                     Region II               /
 ' ACRS                    Licensee 4: O')                              Region IV                 O(
PDR                   HOS, Operations Officer $0$                  Region V j            8804130197 880407                                                         Region III E-IsOO-034DCD

PREWMilfARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-88-34 Date April 7.1988 4                 .
A Region III (Chicago) radiation protection specialist will be sent to the site to review the circumstances of the incident.
The State of Illinois will be informed.
Region III received initial notification of the contamination problem at about 2:30 p.m.,
April 6,1988, from the resident inspector. (The contamination problem was not a reportable incident.) This information is current as of 10 a.m. , April 7,1988.
CONTACT:                            R.l. eg i,0   hW. Shafer   V FTS 388.5644  FTS 388-5656 1
l 1
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