Information Notice No. 83-59: Dose Assignment for Workers in Non-Uniform Radiation Fields

                                                           SSINS No.:  6835 
                                                           IN 83-59        

                               UNITED STATES 
                           WASHINGTON, D.C. 20555 
                             September 15, 1983

Information Notice No. 83-59:   DOSE ASSIGNMENT FOR WORKERS IN 
                                   NON-UNIFORM RADIATION FIELDS 


All nuclear power reactor facilities holding an operating license (OL) or 
construction permit (CP), research and test reactors, fuel cycle facilities,
and all material licensees. 


This information notice provides guidance to licenses on proper dose 
assignment to workers in non-uniform radiation fields. Licensees are 
expected to review the information provided for applicability to their 
facilities. No specific action or response is required. 

Description of Circumstances: 

Several power reactor licensees recently asked the NRC for guidance 
regarding proper assignment of extremity and whole body doses to workers 
involved in a specific steam generator (SG) maintenance activity. In an 
effort to reduce SG corrosion rates, licensees are increasing the frequency 
of sludge lancing--the removal of tubesheet chemical sludge by high pressure 
water jets ("hydrolasing"). Although improved, remote, dose-saving, ALARA 
techniques are becoming more available, workers still are required to 
manually insert an arm (only one at a time) through an SG handhole to 
assemble/disassemble and position sludge lancing equipment. Once the 
equipment is positioned, the actual sludge lancing operations can be 
performed essentially remotely, without exposing the worker to the high SG 
radiation fields. With the arm inserted, the head and trunk of the body are 
in a 1/2-1 R/hr radiation field, the upper arm is in a 3 R/hr radiation 
field, and the forearm and hand are in a 20-40 R/hr radiation field. 

During the course of work the arms are alternated and only one arm at a time
is inserted into the SG. Licensees questioned whether each arm could receive
the allowed quarterly dose, or thinking more conservatively, should the 
doses to the individual arms be additive. Additional guidance requested 
included defining the whole body areas of the arm. A further question 
concerned the applicability of the "skin of the whole body" dose limit to 
the hand and forearm (extremity) areas. 


                                                         IN 83-59          
                                                         September 15, 1983 
                                                         Page 2 of 2       


Each arm can receive a dose up to the applicable regulatory limit. More 
generally, the dose received by each appendage may be separately determined 
and compared to the applicable regulatory limit when irradiation occurs in a 
non-uniform field; however, adequate surveys defining the radiation fields 
and a thorough dose evaluation must be performed to satisfy existing 10 CFR 
Part 20 requirements. Multiple dosimeters may be required to demonstrate 
compliance. Licensees are cautioned that increased personal monitoring 
vigilance for the remainder of the quarter may be required for affected 
workers. Records to satisfy the 20.401 requirements for surveys and 
monitoring results will necessarily become more complex. 

The NRC staff considers the "hand and forearm" to include the hand, the arm 
below the elbow, and the elbow. The whole body is defined in 20.101 to 
include gonads, active blood-forming organs, head and trunk, and lens of the
eye; the staff considers the arm above the elbow as part of the whole body. 
Thus, for the situation described, monitoring should be provided for the 
lower arm area (extremity), the upper arm (part of the whole body), and the 
head and trunk of the whole body. If multiple dosimeters are used to monitor
an area of interest (e.g., front and back of the trunk of the whole body), 
the dose for record keeping purposes is taken from the highest valid 
dosimeter reading. 

The limit to "skin of the whole body" (10 CFR Part 20) does not apply to the
skin of the hand and forearm. Dose to the "hands and forearms" including the
skin is limited to 18-3/4 rems in a quarter. 

Additional guidance on providing adequate personal monitoring is given in IE
Information Notice No. 81-26, Part 3: Placement of Personnel Monitoring 
Devices for External Radiation Exposure (August 28, 1981) and its July 19, 
1982 Supplement No. 1: Clarification of Placement of Personnel Monitoring 
Devices for External Radiation (see Attachments 1 and 2). If you have any 
questions regarding this matter, please contact the Regional Administrator 
of the appropriate NRC Regional Office, or this office. 

                                   Edward L. Jordan, Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response  
                                   Office of Inspection and Enforcement 

Technical Contact:  J. E. Wigginton, IE 
                    (301) 492-4967 

1.   Information Notice No. 81-26, Part 3 
2.   Information Notice No. 81-26, Part 3, Supplement 1 
3.   List of Recently Issued IE Information Notices 

Page Last Reviewed/Updated Friday, May 22, 2015