ANP P R O J E C T PROGRESS R E P O R T
SBRET + 30+37-l(3A
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k
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x 0 0 cm, OR AS SHOWN
2
y CONTRIBUTION S U B T R A C T E D OUT I 0 0 cm, OR A S SHOWN
2
td7 360
348
336
324
342
8, Fig. 14.5. 8 Variable.
300
288
264
252
240
228
246
204
492
480
(deal
Fast-Neutron Dose Rates Near the Right Side, L e f t Side, and Bottom o f the Detector Tank;
be obtained from the differential experiments. For t h i s purpose, the reactor shield surface source can be replaced by a point source because the reactor shield dimensions are small compared with the separation distance. The strength of the equivalent point source per unit solid angle i n a given direction must then equal the integral over the reactor shield surface of the surface source strength per unit area per unit s o l i d angle i n the same direction. Definition of Dose Scattering Probability The probability of the dose from a line beam of fast neutrons scattering into the sides of a cylinder The radiation intensity i s defined i n Fig. 14.16. i n direction (a,#,) i s conveniently given by the dose rate on the surface of a unit sphere at coordinates (a,q5,). T h i s dose i s denoted by De(u,#l). Consider the radiation passing through the elemental area dQ about the point (a,#l) on the unit sphere. If a l l t h i s radiation uniformly intercepted the unit area at coordinate q52 on the side of the cylinder, the dose rate at coordinate # 2 would
208
276
HORIZONTAL ANGLE B E T W E E N p AND d A X E S
equal D e ( a , # l ) d f l . The dose scattering probability for a line beam i s defined as the ratio of the actual dose at # due to the emission from da t o the dose rate w h i c i would have been obtained i f a l l the radiation from dQ had arrived at the unit area about coordinate #2. The dose scattering probability for a line beam i s denoted as P ~ ( C L , # ~#2),
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Ey symmetry, the line-beam dose scattering probability i s a function of the difference in the azimuthal angles (4, #2). Assume that p�(a,#, #2) i s known. L e t the angular distribution of the dose rate on the surface of the unit sphere about the point source 5 be given by D i ( a , # l ) . Then the dose rate at coordinate # 2 on the side of the cylinder i s given by the integral shown in Fig. 14.16. This integral weights the differential dose contribution over the unit sphere by i t s proper scattering probability.
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In are and the
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general, primary reactor shield configurations symmetric about the axis joining the reactor crew compartment, and so the radiation from primary shield is also symmetric about this
s