BERTHOLD TECHNOLOGIES LB 480, Руководство пользователя

Страница: 189 / 450

SENSseries LB 480 Level measurement
BERTHOLD TECHNOLOGIES GmbH & Co. KG
2 – 189
Volume 2 2 Installation
2
2.6
Shielding
Shielding, source type, isotope and activity for each measurement
configuration will be selected together with the customer to ensure
compliance with the local dose rate limits. Co-60 or Cs-137 point
sources are used which are tightly welded into a capsule made of
titan or stainless steel. Therefore, no radioactive material can
escape, provided the source is intact, and contaminations are ruled
out.
For point source shieldings, the capsule with the source is fixed on
a source holder and installed in the shielding. For rod source shield-
ings, a rod source is placed into the existing borehole of the shield-
ing. The shielding matches the length of the source.
The distance from the source shieldings to the vessel surface is
designed such that reaching into the beam channel with the hand is
prevented (reference value approx. 20 mm). For shieldings with a
rotary cylinder (vertically standing cylinder) make sure that the cyl-
inder can be rotated on the vessel surface without friction.
Apart from a few exceptions, all shieldings are filled with lead to
keep the dose rate on the surface with small construction sizes as
low as possible. Therefore, the shieldings are quite heavy. The
weights are listed in the technical drawings in
chapter 5 on page
2-241 .
For information on the design of source and shielding please refer
to the technical documentation and the type plate (
Fig. 2-15 ).
Fig. 2-15 Identity plate
1
2
3
4
5
6
7
8
9
1 Source number
2 Isotope
3 Source manufacture date
4 Shielding material
5 Type of shielding
6 Shielding manufacturer
7 Dose rate in 1m distance
8 Effective shielding thickness
9 Activity