Methods of measurement for discharges/em -Reply

[Charles Willis <CAW@nrc.gov>]

This is in response to the questions from Anna Maria Blixt concerning effluent measurements.

I assume that Vattenfall AB is interested in effluents from nuclear power plants; US controls
for non-power reactors and other facilities are different.  This response addresses the
regulatory requirements which are met in different ways at the different plants.  These
requirements are reasonably well defined in the regulations (10 CFR 50.36a and 10 CFR 50
Appendix I), and the technical reports NUREG 1301 and NUREG-1302.   The following
comments are responses to your specific questions:

1.  The release limits are on dose to the most highly exposed member of the public; the
principal limits are 50 micro-Sv from airborne effluents and 30 micro-Sv from water-borne
effluents annualy.

1a.  For radioiodines and particulates, the requirments specify nuclides with half lives of 8
days or more.  There is no such limit for noble gases.

2.  Noble gases are measured on line.

2a.  The requirements permit the measurements to be gross beta/gamma but such
measurements must be supported with sampling and analysis to determone the isotopic mix.

2b.  The time for acquisition of a spectrum is sample and instrument specific.

2c.  Generally, airborne effluent sampling is continuous but grab samples are called-for in
certain situations such as for discharging the contents of waste gas decay tanks and for
purging containment.

2d.  The detection limits must be low enough to demonstrate compliance with the dose
criteria.

3.  Measured activity is supposed to be reported, even if it is below the technical detection
limit but activity that is not detected need not be reported.

4.  Measurement of carbon-14 is not required.