IE Circular 76-03 - Radiation Exposures in Reactor Cavities

 

CR76003 

                      NUCLEAR REGULATORY COMMISSION 
                   OFFICE OF INSPECTION AND ENFORCEMENT 
                          WASHINGTON, D.C. 20555 
                                     
                            September 10, 1976 

J. P. O'Reilly, Director, Region I 
N. C. Moseley, Director, Region II 
J. G. Keppler, Director, Region III 
E. M. Howard, Director, Region IV
R. H. Engelken, Director, Region V 

IE CIRCULAR 76-03 - RADIATION EXPOSURES IN REACTOR CAVITIES 

The subject document is transmitted for issuance by close of business 
September 13, 1976. The Circular should be issued to all holders of Reactor 
OL's for action and to applicants for, or holders of Reactor CP's for 
information. Also enclosed are draft copies of transmittal letters. 


                                        Dudley Thompson, Acting Director 
                                        Division of Field Operations 
                                        Office of Inspection and 
                                          Enforcement 

Enclosure: 
Circular 76-03 

Transmitted via Wylbur 
9/10/76 11:40 a.m. 
.

(Transmittal letter for Circular 76-03 to each holder of a NRC Operating 
License.) 

Addressee: 

The enclosed Circular 76-03 is forwarded to you for action. The same 
document is being transmitted to each applicant for, or holder of a 
Construction Permit for information. Therefore, if you have a nuclear power 
plant in the construction stage, you will also receive a copy of Circular 
76-03 which will not require a separate response. 


                                        Signature 
                                        (Regional Director) 

Enclosure: 
IE Circular 76-03 
.

(Transmittal letter for Circular 76-03 to each applicant for, or holder of a 
Construction Permit.) 

Addressee: 

The enclosed Circular, 76-03, is forwarded to you for information. No 
response is required. If you are also the holder of a NRC Operating License,
you will also receive a copy of Circular 76-03 which will require a 
response. 


                                        Signature 
                                        (Regional Director) 

Enclosure:
IE Circular 76-03 
.

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

                                                  IE Circular No. 76 - 03 
                                                  DATE: September 13, 1976 

RADIATION EXPOSURES IN REACTOR CAVITIES 

DESCRIPTION OF CIRCUMSTANCES: 

On March 18, 1976, an employee at the Zion station received a "whole body" 
radiation dose of 8 rems or more upon entering the cavity beneath the 
reactor vessel during a refueling outage.  On April 5, 1976, a similar 
reactor cavity entry at Indian Point resulted in a 10-rem whole body dose to 
a licensee employee.  A similar entry on October 5, 1972 caused a 5-rem dose 
to a Point Beach employee. 

These three overexposures appear to have been caused by failure to 
appropriately control entry into high radiation areas, failure to conduct 
adequate surveys and failure to compensate for exposure rate variations that
can occur in various areas in power reactors, e.g., the cavity beneath the 
reactor vessel. With the incore thimbles and detectors inserted into the 
core, radiation levels in the cavity appear to be low. With the thimbles or 
detectors withdrawn into the cavity, however, exposure rates of hundreds or 
possibly thousands of roentgens per hour can exist. Overexposures can occur 
in seconds. 

All three overexposure events involved entry into potentially high radiation
areas without surveys and/or special controls over equipment which could 
cause transients in the exposure rate. 
.

                                                 IE Circular No. 76 - 03 
                                                 Date:  September 13, 1976 

ACTION TO BE TAKEN BY LICENSEES: 

While the three exposures above occurred at pressurized water reactors, 
similar situations could develop at other types of reactors, e.g., pneumatic
irradiation equipment areas (research reactors) and traveling incore probe 
equipment areas (boiling water reactors). Accordingly, holders of power, 
test and research reactor operating licenses are to complete the following: 

1.   Perform a thorough review of plant areas and operations to identify 
     high radiation areas, both continuous and transient, as defined in 
     10 CFR 20.202(b). 

2.   Verify that entryways into high radiation areas are conspicuously 
     posted and locked or otherwise controlled in such a manner as to 
     explicitly identify the nature of the hazard, appropriately control 
     entry, and require adequate pre-entry surveys, 
     
3.   Ensure that radiation protection procedures and radiation protection 
     training and retraining programs specifically address the matter of 
     control of and access to such areas and initiate appropriate retraining
     of all plant personnel, 

4.   Ensure that the procedures governing personnel entry into all actual or
     potential high radiation areas permit such entry only after appropriate
     management review and approval so that conditions within the area are 
     known and not subject to change while the area is occupied, 

5.   Periodically audit whatever controls result from item 1-4, above, to 
     ensure their continued effectiveness, and 

6.   Confirm by written reply within 60 days that the actions for items 1-4 
     above, have been or are being taken. A record, detailing findings, 
     actions taken, and actions to be taken, should be retained for review 
     by NRC during the next radiological safety inspection. 

This request for information was approved by GAO under a blanket clearance 
number B-180225 (R0072); this clearance expires July 31, 1977.