Sixth Erda Workshop on Personnel Neutron Dosimetry

Abstract

Those presenting papers a t the Sixth Workshop prepared summary reports of t h e i r recent work for inclusion in t h i s document. The reports are reproduced here as submitted by the participants, with only minor editing.This y e a r ' s Workshop took a decidedly international flavor, with participants frcm seven countries in addition to the United States. The significance of t h i s group's contribgtions has raised the possibility that the next Neutron Dosimetry Workshop nay be held i n Europe.Of particular i n t e r e s t a t the !40rkshop was the keynote address by Dr. Harald Rossi. He commented t h a t there i s evidence t h a t 1 ) accepted values of RBE f o r low absorbed doses of neutrons may be low by an order of magnitu" or rore and 2 ) t h e risk o f 1 eukemia i s significant a t 0.5 rad t o the bone narrow. A reduction of the 1 imit f o r permissible r,eutron Pexposure, which could r e s u l t from consideration of t h i s information, would necessitate major improvements in our "middle ages" neutron 'r ' dosimetry.A number o f p a r t i c i p a n t s r e p o r t e d conversions t o thermoluminescent dos i m e t e r (TLD) systems. T h i s move has n o t been unanimous, however, as t h e r e were several r e p o r t s o f a p p a r e n t l y s a t i s f a c t o r y f i s s i o n fragment, a c t i v a t i o n' 0 f o i l , and NTA f i l m dosimeters. While t h e m e n t i o n o f NTA f i l m r e s u l t e d i n t h e usual d i s c u s s i o n o f energy c u t o f f and h u m i d i t y e f f e c t s , i t seems t h e use o f I NTA i n a c c e l e r a t o r environments s t i l l has some m e r i t . Discussion o f f i s s i o n fragment dosimeters centered around t r a c k e t c h i n g techniques, which have shown some improvement. Of p a r t i c u l a r i n t e r e s t was Tommasino's r e p o r t on t h e use o f polycarbonate c e n t r i f u g e tubes as t h e s e n s i t i v e element. Thermal l y s t i m u l a t e d exoelectron emission (TSEE) , never v e r y popular f o r personnel dosimetry, has l o s t a d d i t i o n a l ground w i t h t h e r e p o r t t h a t t h e neutron/gamma response r a t i o i s much l e s s than e a r l i e r work had i n d i c a t e d . I n i t i a l work w i t h an experimental Harshaw CaF:thulium TLD shows some promise. T h i s TLD e x h i b i t s a double-humped glow peak (150°C and 240°C), which may p e r m i t separation o f neutron and gamma components from a s i n g l e TLD c h i p .There was a p l e a f o r u n i f o r m i t y i n neutron-to-dose conversion f a c t o r s . A t y p i c a l example o f 120% d i f f e r e n c e s between commonly used f a c t o r s was c i t e d . Perhaps i t i s t i m e f o r a new l o o k a t t h e problem by an i n t e r n a t i o n a l s t a n d a r d s -s e t t i n g group.Measurement of neutron spectra around f a c i l i t i e s would be e a s i e r w i t h a good, p o r t a b l e multichannel analyzer. D r . Harry I n g may have one. I t has 64 channels i n a 6 -i n . x 8 -i n . x 2 1 / 2 -i n . package ( i n c l u d i n g ...