IEC 63121:2020

IEC 63121 ®
Edition 1.0 2020-01
INTERNATIONAL
STANDARD
colour
inside
Radiation protection instrumentation –
Vehicle-mounted mobile systems for the detection of illicit trafficking of
radioactive materials
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IEC 63121 ®
Edition 1.0 2020-01
INTERNATIONAL
STANDARD
colour
inside
Radiation protection instrumentation –

Vehicle-mounted mobile systems for the detection of illicit trafficking of

radioactive materials
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 13.280 ISBN 978-2-8322-7706-5

– 2 – IEC 63121:2020 © IEC 2020
CONTENTS
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions, abbreviated terms and symbols, quantities and units . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms and symbols . 10
3.3 Quantities and units . 11
4 General test procedure . 11
4.1 General . 11
4.2 Standard test conditions . 11
4.3 Uncertainties. 12
4.4 Statistical fluctuations . 12
4.5 Background radiation during testing . 12
4.6 Operating parameters and set up . 12
4.7 Setup and test parameters . 12
4.8 Dynamic testing . 13
4.9 Static testing . 13
4.10 Radiation sources . 14
4.11 Special nuclear material (SNM) and depleted uranium (DU) sources . 15
4.12 Functionality test and test acceptance range requirements . 16
4.12.1 General requirements . 16
4.12.2 Pre-test measurements . 17
4.12.3 Intermediate-test measurements . 18
4.12.4 Post-test measurements . 18
4.12.5 Acceptance criteria . 19
5 General requirements . 19
5.1 General characteristics . 19
5.2 Physical configuration . 20
5.3 Data storage and data files . 20
5.3.1 Requirements . 20
5.3.2 Method of test. 21
5.4 Communications protocol . 21
5.4.1 Requirements . 21
5.4.2 Method of test. 21
5.5 Indication and alarm features . 21
5.5.1 Requirements . 21
5.5.2 Method of test. 21
5.6 Markings . 22
5.6.1 Requirements . 22
5.6.2 Method of test. 22
5.7 Power supply . 22
5.7.1 Requirements . 22
5.7.2 Method of test. 22
5.8 User interface . 22
5.8.1 User accessible controls requirements . 22
5.8.2 Supervisory-user accessible indications and functions requirements. 22
5.8.3 User display and visual indicators requirements . 23

5.8.4 Warning indicators requirements. 23
5.8.5 Method of test. 23
6 Radiological tests . 24
6.1 False alarm test . 24
6.1.1 Requirements . 24
6.1.2 Method of test. 24
6.2 Gamma radiation alarm . 24
6.2.1 Requirements . 24
6.2.2 Method of test. 25
6.3 Neutron radiation alarm . 25
6.3.1 Requirements . 25
6.3.2 Method of test. 25
6.4 Over-range indication . 25
6.4.1 Requirements . 25
6.4.2 Method of test. 26
6.5 Neutron indication in the presence of photons . 26
6.5.1 Requirements . 26
6.5.2 Method of test. 26
6.6 Slowly approaching source—vehicle-mounted mobile system is stationary
during use . 27
6.6.1 Requirements . 27
6.6.2 Method of test. 27
6.7 Background effects—vehicle-mounted mobile system is mobile during use . 27
6.7.1 Requirements and background information . 27
6.7.2 Method of test. 28
6.8 Radionuclide identification—when provided . 30
6.8.1 Radionuclide categorisation . 30
6.8.2 Single radionuclide identification . 31
6.8.3 Simultaneous radionuclide identification . 32
6.8.4 Radionuclide not in library . 32
7 Climatic requirements . 33
7.1 General . 33
7.2 Ambient temperature. 34
7.2.1 Requirements . 34
7.2.2 Method of test. 34
7.3 Relative humidity . 34
7.3.1 Requirements . 34
7.3.2 Method of test. 34
7.4 Dust and moisture protection . 35
7.4.1 Requirements . 35
7.4.2 Method of test—dust . 35
7.4.3 Method of test—moisture . 35
8 Mechanical requirements . 35
8.1 Microphonics/impact . 35
8.1.1 Requirements . 35
8.1.2 Method of test. 36
8.2 Vibration . 36
8.2.1 Requirements . 36
8.2.2 Method of test. 36

– 4 – IEC 63121:2020 © IEC 2020
9 Electrical and electromagnetic requirements . 36
9.1 Electrostatic discharge (ESD) . 36
9.1.1 Requirements . 36
9.1.2 Method of test. 36
9.2 Radio frequency (RF) . 37
9.2.1 Requirements . 37
9.2.2 Method of test. 37
9.3 Radiated emissions . 37
9.3.1 Requirements . 37
9.3.2 Method of test. 37
9.4 Battery lifetime . 37
9.4.1 Requirements . 37
9.4.2 Method of test. 37
10 Documentation . 38
10.1 Report. 38
10.2 Operation and maintenance manual . 38
Annex A (informative) Uranium/plutonium detection and identification guidance . 39
Bibliography . 40

Figure 1 – Reference point diagram for a two-sided vehicle-mounted mobile system
(top down view) . 14
Figure 2 – Increasing background with source . 29
Figure 3 – Decreasing background with source . 29

Table 1 – . 11
Standard test conditions
Table 2 – Setup and test parameters . 13
a
Table 3 – Test radionuclides and materials used for Clause 6 of this document . 15
Table 4 – SNM fluence rates . 16
Table 5 – Test results analysis . 19
Table 6 – Radionuclide library . 30
Table 7 – Radionuclide decay products and impurities . 30

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RADIATION PROTECTION INSTRUMENTATION –
VEHICLE-MOUNTED MOBILE SYSTEMS FOR THE DETECTION
OF ILLICIT TRAFFICKING OF RADIOACTIVE MATERIALS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 63121 has been prepared by subcommittee 45B: Radiation
protection instrumentation, of IEC technical committee 45: Nuclear instrumentation.
The text of this standard is based on the following documents:
FDIS Report on voting
45B/946/FDIS 45B/955/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 6 – IEC 63121:2020 © IEC 2020
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
INTRODUCTION
Illicit and inadvertent movement of radioactive materials in the form of radiation sources and
contaminated metallurgical scrap has become a problem of increasing importance.
Radioactive sources out of regulatory control, so-called “orphan sources”, have frequently
caused serious radiation exposures and widespread contamination. Although illicit trafficking
of nuclear and other radioactive materials is not a new problem, concern about a nuclear
“black market” has increased, particularly in view of its terrorist potential.
In response to the technical policy of the International Atomic Energy Agency (IAEA), the
World Customs Organization (WCO), and the International Criminal Police Organization
(Interpol) related to the detection and identification of special nuclear materials and security
trends, radiation instrumentation companies have developed and manufactured instruments to
assist in the detection of illicit movement of radioactive and special nuclear materials. This
type of instrumentation is widely used for security purposes at nuclear facilities, border control
checkpoints, and international seaports and airports.
To ensure that measurement results made at different locations are consistent, it is imperative
that radiation instrumentation be designed to rigorous specifications based upon agreed
performance requirements stated in this document. IEC standards have also been developed
to address personal radiation detectors, radiation portal monitors, highly sensitive gamma and
neutron detection systems, spectrometric personal radiation detectors, and backpack-based
radiation detection and identification systems. Those standards are listed below.
Type of IEC
Title of the standard
instrumentation number
Radiation protection instrumentation – Alarming Personal Radiation Devices
(PRDs) for the detection of illicit trafficking of radioactive material
Radiation protection instrumentation – Spectroscopy-Based Alarming Personal
Body-worn 62618 Radiation Devices (SPRD) for the detection of illicit trafficking of radioactive
material
Radiation protection instrumentation – Backpack-type radiation detector (BRD) for
the detection of illicit trafficking of radioactive material
Radiation protection instrumentation – Hand-held instruments for the detection and
62327 identification of radionuclides and for the estimation of ambient dose equivalent
rate from photon radiation
Portable or
Radiation protection instrumentation – Highly sensitive hand-held instruments for
hand-held
photon detection of radioactive material
Radiation protection instrumentation – Highly sensitive hand-held instruments for
neutron detection of radioactive material
Radiation protection instrumentation – Installed radiation portal monitors (RPMs)
for the detection of illicit trafficking of radioactive and nuclear materials
Portal
Radiation protection instrumentation – Spectroscopy-based portal monitors used
for the detection and identification of illicit trafficking of radioactive material
Radiation protection instrumentation – Vehicle-mounted mobile systems for the
Mobile system 63121
detection of illicit trafficking of radioactive materials
Radiation protection instrumentation – Data format for radiation instruments used
Data format 62755
in the detection of illicit trafficking of radioactive materials

– 8 – IEC 63121:2020 © IEC 2020
RADIATION PROTECTION INSTRUMENTATION –
VEHICLE-MOUNTED MOBILE SYSTEMS FOR THE DETECTION
OF ILLICIT TRAFFICKING OF RADIOACTIVE MATERIALS

1 Scope
This document applies to vehicle-mounted mobile systems (also known as mobile systems or
mobile monitors) that are used for the detection of illicit trafficking of radioactive materials;
these instruments may also be used for protection of major public events and for rapid
screening of large areas. These vehicle-mounted mobile systems consist of one or more
radiation detectors mounted in a vehicle, e.g., car or van, which travels predominantly on
public roads. This document does not apply to detection systems mounted in other types of
vehicles, e.g., planes, helicopters, trains, or boats. Vehicle-mounted detection systems
covered by this document are designed to detect radioactive sources while the vehicle is in
motion. They may also be used as stationary monitors that scan stationary or moving objects.
Vehicle-mounted mobile systems detect gamma radiation and may include neutron detection
and/or identification of gamma-ray emitting radionuclides.
The purpose of this document is to set minimum requirements for vehicle-mounted mobile
systems for the detection of radioactive material. This document establishes general,
radiological, climatic, mechanical, electric and electromagnetic, and documentation
requirements, and the associated test methods.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050-395:2014, International Electrotechnical Vocabulary (IEV): Part 395: Nuclear
instrumentation: physical phenomena, basic concepts, instruments, systems, equipment and
detectors
IEC 61187, Electrical and electronic measuring equipment – Documentation
IEC 62706, Radiation protection instrumentation – Environmental, electromagnetic and
mechanical performance requirements
IEC 62755, Radiation protection instrumentation – Data format for radiation instruments used
in the detection of illicit trafficking of radioactive materials
3 Terms and definitions, abbreviated terms and symbols, quantities and units
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-395, as well
as the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
acceptance test
contractual test to prove to the customer that a device meets certain conditions of its
specification
3.1.2
alarm response
audible signal or visual signal, initiated when the reading of an instrument exceeds a pre-set
value or falls outside a pre-set range
3.1.3
ambient dose equivalent
dose equivalent at a point in a radiation field, produced by the corresponding aligned and
expanded field, in the ICRU sphere at a depth d, on the radius opposing the direction of the
aligned field
Note 1 to entry: This definition does not include the notes that are part of the definition
IEC 60050-395:2014,395-05-43.
3.1.4
background
radiation field in which there are no external sources present other than those in the natural
radiation field at the location of the measurements
3.1.5
categorisation
ability of an instrument to determine the type of radioactive material based on its emitted
radiation, e.g., naturally occurring radioactive material, nuclear material, medical
radionuclides, and industrial sources
3.1.6
coefficient of variation
ratio of the standard deviation to the mean of a value
3.1.7
coverage factor
k
numerical factor, k, used as a multiplier of the combined standard uncertainty in order to
obtain an expanded uncertainty
3.1.8
detection zone
location from which radiation emitted by an object being monitored may be detected by the
detection assembly
3.1.9
error of indication
difference between the indicated value ν of a quantity and the conventionally true value ν of
c
that quantity at the point of measurement

– 10 – IEC 63121:2020 © IEC 2020
3.1.10
nuclear material
plutonium except that with isotopic concentration exceeding 80 % in plutonium-238 ( Pu);
233 235 233
uranium-233 ( U); uranium enriched in the isotope 235 or 233 ( U or U); uranium
containing the mixture of isotopes as occurring in nature other than in the form of ore or ore-
residue; any material containing one or more of the foregoing
[SOURCE: IAEA-TECDOC-1311, September 2002]
3.1.11
reference point
location marked on the instrument or described in the manual used to establish radiation
source to instrument distances and orientation for test or calibration purposes
3.1.12
relative intrinsic error
relative error of indication of a piece of equipment or an assembly with respect to a quantity
when subjected to a specified reference quantity under specified reference conditions,
expressed as:
e = (v – v )/v ,
i c c
where
v is the indicated value of a quantity, and
v is the conventionally true value of this quantity at the point of measurement.
c
Note 1 to entry: Simple definition: error of a measuring instrument when used under reference conditions.
3.1.13
type test
conformity test made on one or more items representative of the production
3.1.14
uncertainty
parameter, associated with the result of a measurement, that characterises the dispersion of
the values that could reasonably be attributed to the measurand
3.2 Abbreviated terms and symbols
AAI additional acceptable identification
CISPR Comité International Spécial des Perturbations Radioélectriques (Special
International Committee on Radio Interference)
COV coefficient of variation
DU depleted uranium
ESD electrostatic discharge
HDPE high-density polyethylene
HEU highly-enriched uranium
ICRU International commission on radiation units and measurements
NORM naturally occurring radioactive material
PMMA polymethyl methacrylate
RF radio frequency
RGPu reactor grade plutonium
RI required identification
SNM special nuclear material
WGPu weapons-grade plutonium
3.3 Quantities and units
In the present document, units of the International System (SI) are used . The definitions of
radiation quantities are given in IEC 60050-395.
The following units may also be used:
-19
– for energy: electron-volt (symbol: eV), 1 eV = 1,602 × 10 J;
– for time: years (symbol: y), days (symbol: d), hours (symbol: h), minutes (symbol: min);
– for temperature: degrees Celsius (symbol: ºC), 0 ºC = 273,15 K.
Multiples and submultiples of SI units are used, when practicable, according to the SI system.
4 General test procedure
4.1 General
Unless otherwise specified in an individual step, tests enumerated in this document may be
used as part of a type test or an acceptance test.
4.2 Standard test conditions
Except where otherwise specified, the tests described in this document should be performed
under the standard test conditions given in Table 1, understanding that vehicle-mounted
mobile systems may be large, and that testing may need to be performed in an uncontrolled
environment. The ambient temperature, relative humidity, and atmospheric pressure shall be
recorded during testing.
Table 1 –
Standard test conditions
Influence quantity Standard test conditions
Ambient temperature 18 °C to 25 °C
Relative humidity ≤ 75 %
Atmospheric pressure 70 kPa to 106,6 kPa
-1
Gamma radiation background Ambient dose equivalent rate less than or equal to 0,15 μSv•h
-1 -2
Neutron background Neutron fluence rate less than 200 s •m

NOTE Vehicle-mounted mobile systems are typically used in non-radiological areas, e.g., shipping ports and
border locations. Man-made radiological materials such as radiation sources are not expected to be present in
these areas. Non-radiological areas are expected to be used when testing vehicle-mounted mobile systems.
_____________
th
International Bureau of Weights and Measures: The International System of Units, 8 edition, 2006.

– 12 – IEC 63121:2020 © IEC 2020
4.3 Uncertainties
The radiation field or ambient dose equivalent rate uncertainty should not exceed ±20 %,
except for the radiation background measurements, for which the uncertainty may be larger
than the value stated here. Unless otherwise stated, the uncertainties are specified with a
coverage factor k = 1.
4.4 Statistical fluctuations
For tests involving the use of radioactive sources to verify susceptibility to a climatic,
electromagnetic, or mechanical condition (Clauses 7, 8, and 9), the radiation field produced
by the sources to verify the vehicle-mounted mobile system response shall be adjusted to
reduce the magnitude of the statistical fluctuations.
If the magnitude of the statistical fluctuations of the vehicle-mounted mobile system indication
arising from the random nature of radiation alone is a significant fraction of the variation of the
indication permitted in the test (i.e., fluctuations greater than 12 %), then the radiation field
should be increased to reduce the fluctuation of the readings (to ensure that the mean value
of such readings may be estimated with sufficient accuracy to demonstrate compliance with
the test in question). If the radiation field cannot be increased to meet the required coefficient
of variation (COV) then the number of readings should be increased as necessary. The COV
for the nominal mean reading shall be less than or equal to 12 %.
For measurements without sources (i.e., at the level of background radiation), the vehicle-
mounted mobile system is observed in order to verify that alarms and spurious indications are
not produced by an influence quantity (e.g., temperature, humidity, RF, impact, vibration), as
readings are expected to display large fluctuations. Therefore, testing without sources can be
performed even when the COV is larger than 12 %.
4.5 Background radiation during testing
Testing shall be performed in an area having a radiation background as defined in Table 1.
The background shall be measured prior to testing and monitored during testing. A
background spectrum shall also be acquired using a spectroscopic (e.g., high-purity
germanium [HPGe]) detector to ensure that only naturally-occurring radionuclides (e.g., K,
232 238
Th series, U series) are present in the testing area. The neutron background should be
measured unless it can be confirmed that no neutron sources are in the test area. The
elevation at the test location shall be recorded.
4.6 Operating parameters and set up
Vehicle-mounted mobile systems shall be set up based on the manufacturer’s specifications.
Operating parameters such as alarm settings should remain unchanged throughout the test.
For testing purposes, the reference point is the centre point of the detection assembly face or
the adjacent side of the vehicle to which the detection assembly is mounted; see Figure 1.
The testing distance is measured from the front face of the detection assembly; it is not
measured from the outside of the vehicle.
The vehicle-mounted mobile system shall be oriented as defined by the manufacturer. If the
vehicle-mounted mobile system requires a background measurement, it shall be allowed to
acquire the data in a manner specified by the manufacturer prior to the start of a test.
4.7 Setup and test parameters
Setup and test parameters are given in Table 2.

For testing purposes, the height of the detection zone is defined as ranging from 1 m to 3 m
above the ground or road surface. The detection assembly shall be placed at the height
specified by the manufacturer. Additional setup and test parameters are listed in Table 2 and
illustrated in Figure 1.
Table 2 – Setup and test parameters
Source to reference point distance Dynamic speed Measurement time for static
testing
-1
cm s
m•s
300 ± 1 2,2 ± 0,2 60
If the vehicle-mounted mobile system is two-sided, i.e., it utilises radiation detectors mounted
on each side of the vehicle, then each side of the system should be tested independently. If
the detector assemblies on both sides of the system are the same, it is not necessary to test
both detector assemblies.
4.8 Dynamic testing
Unless otherwise stated, each source shall be passed horizontally through the middle of the
bottom half and the middle of the top half of the detection zone (i.e., 1,5 m and 2,5 m from the
ground) at the speed and distance provided in Table 2. The source shall be configured such
that there is no shielding around the source other than that required for a specific test. The
vehicle-mounted mobile system’s alarm shall be reset between successive trials, if
appropriate and as needed. There shall be a 10 s minimum delay between each trial with the
source either shielded or positioned at a distance where it does not affect the background
surrounding the vehicle-mounted mobile system.
4.9 Static testing
With the vehicle-mounted mobile system set up for a static measurement, place each source
at the vertical centre of the detection zone (i.e., at 2 m from the ground), in the horizontal
centre of the detection assembly, with the source at a distance of 3 m from the reference
point, and initiate a measurement cycle for the static measurement time shown in Table 2.
The vehicle-mounted mobile system’s alarm shall be reset between each trial, if appropriate
and as needed.
– 14 – IEC 63121:2020 © IEC 2020

Key
X
Source direction for dynamic test
Reference point position
Detector(s)
Detection assembly
Source
Figure 1 – Reference point diagram for a two-sided
vehicle-mounted mobile system (top down view)
4.10 Radiation sources
All radiation sources used for radiological testing (Clause 6) are listed in Table 3. The activity,
emission rate, and fluence rate values at the time of testing shall be within (-0 %, +20 %) of
the value shown in this table. Sources used for testing shall be traceable to the SI system of
units through a national metrology institute. Source activities listed in Table 3 are based on
photons emitted by stainless steel (0,25 mm thick) encapsulated sources; this does not apply
to special nuclear material (SNM) sources. The specified activities are determined by the
desired source emission rate. If the source is of a different construction, it is required to have
the same emission rate for the selected photon energy listed in Table 3.
252 244
Cf or Cm is the reference source for neutron alarm testing. The source shall have a
-1
neutron emission rate of 20 000 s (-0 %, +20 %) and, unless otherwise stated, be
surrounded by a spherical high-density polyethylene (HDPE) moderator with a wall thickness
of 4 cm. The inner cavity diameter of the moderator should be no larger than 3 cm.
NOTE Due to radioactive decay, the emission rate of the Cf source will be within the stated range of 20 000 –
-1 244
24 000 s for ~8 months; for Cm, the emission rate will be in the stated range for ~4,7 y.
Medical radionuclides shall be surrounded by (8 ± 0,4) cm of polymethyl methacrylate (PMMA)
to represent in-vivo configurations.

The test activities used for detection and identification purposes are not indicative of the
alarm set point(s) or overall detection capability of a vehicle-mounted mobile system.
a
Table 3 – Test radionuclides and materials used for Clause 6 of this document
Radionuclide Activity or neutron emission rate Selected gamma-ray line
keV
1,74 MBq 60
Am
370 kBq 276
Ba
370 kBq 1173
Co
590 kBq 662
Cs
252 244 4 -1
N/A
Cf or Cm 2 × 10 s
Ga 3,5 MBq
I 850 kBq
99m
Tc 4,7 MBq
Tl 8,3 MBq
590 kBq 295
Ra
232 b
700 kBq 239
Th
-1 -2
Source
Gamma fluence rate (s •cm ) at 1 m

DU 1,04 (See 4.11) 1001
HEU 1,44 (See 4.11) 186
WGPu 0,40 (See 4.11) 375
a
The activity, emission rate, and fluence rate values at the time of testing shall be within (-0 %, +20 %) of
the values shown in this table. The uncertainty in the actual activity value shall be less than or equal to
±5 % (1 σ, k = 1) for the gamma-ray sources. The uncertainty in the fluence rate shall be ±10 %
(1 σ, k = 1) for the HEU, WGPu, and DU sources. The uncertainty in the neutron emission rate shall be
252 244
±10 % (1 σ, k = 1) for the Cf or Cm source.
b 232
The Th source activity is based on thorium metal rods 3,5 mm thick.

4.11 Special nuclear material (SNM) and depleted uranium (DU) sources
For this document, highly-enriched uranium (HEU) has an enrichment that is ≥90 % U,
depleted uranium (DU) has a U abundance of 0,2 % to 0,4 %, and weapons-grade
240 239
plutonium (WGPu) has composition of ≤6,5 % Pu and >93 % Pu.
NOTE The fluence rate stated in Table 4 for HEU is based on the emission rate from an HEU sphere with a mass
of approximately 237 g. The fluence rate for WGPu is based on the emission rate from a WGPu sphere having a
mass of approximately 15 g and surrounded by 1 cm thick Fe. The DU fluence rate is based on the emission rate
from the side wall (along the equator) of a 10 kg right circular cylinder of DU with a diameter
...