2011 EMC Directory & Design Guide - Interference Technology

K e e bl e r, Berge r
and identify new needs to replace older analog I&C equipment.
For various reasons, some plants plan and request
limited-scope surveys at the point-of-installation (POI).
Surveys are carried out to gain additional knowledge regarding
the EME prior to the upgrade and how the installation
of the new equipment affected the EME. Of the surveys that
EPRI has carried out between 2001 and 2010, unexpected
knowledge regarding the EME was always learned after the
survey. Utility customers reported after their review with
the NRC regarding their digital upgrade projects that the
initiative taken to do the survey and the information gained
from doing it were positive steps in helping the plant, the
NRC, and the NPP industry to understand more about
EMC concerns and help achieve enhanced EMC for digital
upgrade projects.
Secondly, utility engineers engaged in the design of
advanced NPPs have expressed the importance of having
POI surveys carried out prior to actually constructing new
advanced plants. One might ask, “How can this be done?” As
part of the design process, a pre-operational demonstration
is built for the digital I&C equipment planned for use in new
plants. Survey activities can be carried out in these areas
for each utility planning an advanced plant. Measurements
to characterize the low-frequency radiated magnetic fields
and low- and high-frequency radiated electric fields can
be made. Conducted emissions measurements of low- and
high-frequency can also be made. In fact, there is technical
benefit to making these measurements in these areas away
from the cluttered EMEs of advanced plants after they are
built. Data from such measurements will be useful in the
development of an emissions analysis database and can be
used to compare to the emissions captured during EMC
certification of digital I&C equipment, emissions from analog
I&C equipment, from historical surveys in existing plants,
recent surveys in existing plants and emissions captured
when advanced plants are completed as well as emissions
captured during an EMI investigation.
radiated emissions
If requested as a part of the survey, conducted emissions
could have been measured along power and data cables on
the existing analog control system. This in situ study on a
DCS is the first of its kind. Only the electric field emissions
from 10 kHz to 6 GHz are reported in this paper.
Once the DCS was set up for testing and training in the
TTF facility, a second visit was made to the site. The same
groups of measurements were made but with the DCS
mounted only in wooden racks without any metallic system
cabinets in place. (These measurements are not provided
here.) After the DCS was installed and operational, the next
visit was made to the site where emissions measurements
(discussed in this paper) were again made in the control
room at the same antenna positions. Measurements were
also taken with selected system cabinet doors open for
comparison but are also not included in this paper. A new
automated emissions measurement system, developed by
EPRI was used to capture the emissions data and is further
described in Section III. B.
MEASUREMENT METHODS FOR COLLECTING
RADIATED EMISSIONS DATA
The NRC NUREG 1.180 (Rev. 1) 2003 and the
EPRI TR-102323 (Rev. 3) 2004 Documents
The document, “Guidelines for Evaluating Electromagnetic
ABOUT THE ORIGINAL SURVEY PROJECT FOR
DCS UPGRADE
As a part of the digital control system (DCS) upgrade program
for Units 1 and 2, a major US nuclear power plant
requested that a survey for radiated magnetic and electric
fields be conducted in three areas: 1) Control Room – near
the system cabinets in the control room where the existing
analog control system is to be retrofitted with the new
digital control system for Units 1 and 2, 2) the Operator
Assist Computer (OAC) Computer Room area for Units 1
and 2, and 3) the Testing and Training Facility (TTF) Facility
where the DCS was set up for testing. A survey plan
was designed to investigate the radiated EME in each areas.
The investigation was carried out by conducting a partial
EMC survey measuring the radiated emissions for Unit 1
and 2 for electric fields from 10 kHz to 6 GHz and for magnetic
fields from 20 Hz to 100 kHz with the analog control
system in place and operational. A full EMC survey would
entail measuring both radiated and conducted emissions.
interferencetechnology.com interference technology 93