Neutron Radiography Handbook Nuclear Science and Technology

Radiography with neutrons can yield important information not obtainable by more traditional methods. In contrast to X-rays as the major tool of visual non-destructive testing, neutrons can be attenuated by light materials like water, hydrocarbons, boron, penetrate through heavy materials like steel, lead, uranium, distinguish between different isotopes of certain elements, supply high quality radiographs of highly radioactive components. These advantages have led to multiple applications of neutron radiography since 1955, both for non-nuclear and nuclear problems of quality assurance. The required neutron beams originate from radioisotopic sources, accelerator targets, or research reactors. Energy "tailoring" which strongly influences the interaction with certain materials adds to the versatility of the method. Since about 1970 norms and standards have been introduced and reviewed both in Europe (Birmingham, September 1973) and the United States (Gaithersburg, February 1975). The first world conference on neutron radiography will take place in December 1981, in San Diego, U.S.A. . In Europe the interested laboratories inside the European Community have entered into systematic collaboration through the Neutron Radiography Working Group (NRWGl. since May 1979. This Handbook has been compiled as one of the common tasks undertaken by the Group. Its principal authors are J.C. Domanus (Ris0 National Laboratory). and R.S. Matfield (Joint Research Centre, Ispra) Major contributions have been received from R. Liesenborgs (SCK/CEN Mol) R. Barbalat (CEN Saclayl.

1. Principles and Practice of Neutron Radiography.- 1.1 Introduction to Neutron Radiography.- 1.1.1 Historical.- 1.1.2 Basic Concepts.- 1.1.3 Neutron Sources.- 1.1.3.1 Accelerators.- 1.1.3.2 Radioisotopes.- 1.1.3.3 Thermal Nuclear Reactors.- 1.1.3.4 Sub-critical Assemblies.- 1.1.3.5 A Comparison of Neutron Sources.- 1.1.4 Neutron Beam.- 1.1.4.1 Nuclear Cross Sections.- 1.1.4.2 Moderation.- 1.1.4.3 Collimation.- 1.1.5 Neutrons Applied to Radiography.- 1.1.6 Neutron Image Detectors.- 1.1.6.1 Direct Technique.- 1.1.6.2 Transfer Technique.- 1.1.6.3 Dynamic Imaging Methods.- 1.1.7 Image Recorders.- 1.1.7.1 Photographic Film and its Characteristics.- 1.1.7.2 Track-Etch Recorders.- 1.1.8 Film and Foil Relationships.- 1.1.8.1 Film and Foil Speed.- 1.1.8.2 Film and Foil Resolution.- 1.1.8.3 Some Observations on Resolution Sensitivity.- 1.1.9 Neutron Beam Filters.- 1.1.10 Tomography.- 1.2 The Design of Neutron Radiography Equipment.- 1.2.1 The Choice of Neutron Source.- 1.2.2 Collimator.- 1.2.2.1 Collimator Design.- 1.2.2.2 Characteristics of Lining Materials.- 1.2.2.3 Defining of the Inlet Aperture.- 1.2.2.4 Divergence-Angle.- 1.2.2.5 Geometric Enlargement and Diminution.- 1.2.3 Converter Foils.- 1.2.3.1 Characteristics of Foil Materials.- 1.2.3.2 Foil Thickness and Speed.- 1.2.3.3 Film and Foil Resolution.- 1.2.3.4 The Mounting of Foils.- 1.2.3.5 Enrichment of Converter Foils.- 1.3 Applications of Neutron Radiography.- 1.3.1 Nuclear Applications.- 1.3.2 Industrial Applications.- 1.3.3 Biomedical Applications.- 1.3.4 Other Applications.- 1.4 List of Symbols Used.- 1.5 References.- Appendices.- Appendix 1.1 Neutron Radiographic Terminology.- Appendix 1.2 Thermal Neutron Cross Sections of the Elements and Some Materials.- Appendix 1.3 Irradiation and Transfer Times for the Indirect Method.- Appendix 1.4 Resolution of Voids.- Appendix 1.5 The Calculation of the Cross Section of a Compound.- 2. Recommended Practice for the Neutron Radiography of Nuclear Fuel.- 2.1 Applicable Documents.- 2.2 Ordering Information.- 2.3 Equipment.- 2.3.1 General.- 2.3.2 Geometry.- 2.3.3 Neutron Energy.- 2.3.4 Beam Quality.- 2.4 Radiographic Techniques.- 2.4.1 General.- 2.4.2 Set-Up, Marking and Identification.- 2.4.3 Image Converters.- 2.4.4 Image Recorders.- 2.4.5 Cassettes.- 2.4.6 Masking and Backscatter Protection.- 2.4.7 Geometry.- 2.4.8 Density of the Radiograph.- 2.4.9 Contrast.- 2.4.10 Image Quality Indicators.- 2.4.11 Exposure Chart/Techniques Log.- 2.4.12 Track-Etch Techniques.- 2.5 Measurement.- 2.5.1 Definition and Methods.- 2.5.2 The Principles of Radiographic Measurement.- 2.5.3 The Neutron Radiographic Technique.- 2.5.4 Making the Radiograph.- 2.5.5 Making the Measurements.- 2.5.6 Image Enhancement.- 2.6 Safety Precautions.- 2.7 Film Handling.- 2.7.1 Storage of Film.- 2.7.2 Safelight Test.- 2.7.3 Cleanliness and Film Handling.- 2.8 Film Processing.- 2.8.1 General.- 2.8.2 Automatic Processing.- 2.8.3 Manual Processing.- 2.9 Viewing Radiographs.- 2.10 Reference Radiographs.- 2.11 Storage of Radiographs.- 2.12 Records and Reports.- 2.12.1 Records.- 2.12.2 Reports.- 3. NRWG indicators for testing of Beam Purity, Sensitivity, and Accuracy of Dimensions of Neutron Radiographs.- 3.1 The Various Indicators.- 3.1.1 Beam Purity Indicator (BPI).- 3.1.2 Beam Purity Indicator-Fuel (BPI-F).- 3.1.3 Sensitivity Indicator (SI).- 3.1.4 Calibration Fuel Pin (CFP-E1).- 3.2 Assessment of Test Results for the Indicators.- 3.2.1 Assessment for the Beam Purity Indicator (BPI).- 3.2.2 Assessment for the Beam Purity Indicator-Fuel (BPI-F).- 3.2.3 Assessment for the Sensitivity Indicator (SI).- 3.2.4 Assessment for the Calibration Fuel Pin (CFP-E1).- 3.3 References.- 4. Atlas (Compact Version) of Defects Revealed by Neutron Radiography in Light Water Reactor Fuel.- 4.1 Introduction.- 4.2 Relevant Notes.- 4.2.1 Fuel Pins.- 4.2.2 Defect.- 4.2.3 Defect Location.- 4.2.4 Defect Nature and Origin.- 4.2.5 Defect Occurrence.- 4.2.6 Defect Intensity.- 4.2.7 Dimensions.- 4.2.8 Measuring of Dimensions.- 4.3 The Collection of the Atlas.- 4.3.1 Contents of the Collection.- 4.3.2 The Use of the Collection.- 4.3.3 The Selection of Characteristic Defects.- 4.4 References.- 5. Neutron Radiography Installations in the European Community. Tables and Figures.- Table 5.1 Neutron Radiography Installations in the European Community Technical Data and Main Utilization.- Table 5.2 Neutron Radiography Installations in the European Community Exposure Techniques.- Table 5.3 Neutron Radiography Installations in the European Community Qualitative Analysis, Quantitative Analysis.- Table 5.4 Neutron Radiography Installations in the European Community Future Needs and Requirements.- Figures : Cadarache, LDAC.- Casaccia, TRIGA-RC1.- Fontenay-aux-Roses, Triton.- Geesthacht, FRG 1, FRG 2, 1 kCi Sb-Be.- Grenoble, Melusine, Siloe.- Harwell, DID0 6H, DIDO 6HGR9.- Karlsruhe, FR 2.- Mol, BR 1, BR 2.- Petten (JRC), PSF, HB8.- Petten (ECN), LFR.- Ristø, DR 1.- Saclay, OSIRIS, ISIS (2 installations), Orphee.- Valduc, Mirene.