Several passive devices, including alpha track detectors, charcoal canisters, charcoal liquid scintillation detectors, and electret ion chambers
, are all effective testing options.
A vibrating reed ion chamber instrument normally used as a laboratory device (3) was fitted with a gasoline powered generator and taken to the site for measurements.
Three of those badges were kept at locations away from the site and used as reference monitors; the background used by the supplier to obtain net results for the set was based on the response of an ion chamber at the supplier's distribution center, in California, The data from the program was only selectively preserved; the recorded data on file show only one set from 1966 and one from 1969, with full years of information for 1967 and 1968, although full term monitoring for all the years is implied in internal publications (2).
Shonka generously provided a prototype of his tissue equivalent ion chamber and electronics (5) to test as an environmental monitor at the new NBS site.
A commercial version (4) of the instrument, with a true spherical shape for the ion chamber and more stable and easily controlled electronics, was procured and placed in service.
In 1990, a high-pressure ion chamber (6) (HPIC) was taken to each of the surveyors' markers and a measurement of at least 24 h was made.
Among the current tests and investigations, the electret ion chamber radiation detector (14) and a geiger tube (G-M) monitor with a variable count accumulation time (15) have shown much promise.
set 1973 Jan Feb Mar 1 Apr 1 May 1 Jun 1 Jul 1 Aug Sep 1 Oct 1 Nov Dec Table 6 High pressure ion chamber data Meas, period Location Air kerma rate and 1 s.