Validation of capture reactions cross sections in Cf(s.f.) neutron field.

We have investigated following capture reactions: Au(n,g)Au, Cu(n,g)Cu, Sc(n,g)Sc, Ta(n,g)Ta, Ce(n,g)Ce, La(n,g)La, Yb(n,g)Yb, Mn(n,g)Mn, and Pr(n,g)Pr in a standard Cf(s.f.) neutron field.

Measurement of spectral averaged cross sections of capture reactions in the LR-0 reference neutron field.

Nuclear data evaluations are periodically updated to render state of the art of knowledge, and the independent validation experiments are still of interest of the community. Current work describes validation of selected capture reactions used for monitoring of thermal neutrons in mixed fields, as well as reactions responsible for activation of components exposed to neutron flux. The validation was performed also for reaction Cr (n,γ), which is very important reaction directly affecting criticality safety, because chromium is essential component of stainless steel used as structural component of the core baffle closely adjoining to nuclear fuel.

The spectrum-averaged cross section investigation of Sn(n,n')Sn and Zn(n,p)Cu reactions.

The spectrum averaged cross sections (SACS) in standard neutron field, e.g. Cf(s.

Experimental validation of Na( γ, n)Na cross section.

Photonuclear reactions are gaining importance due to their influence on the shielding and activation of components of widely spread accelerators. Therefore, there is a need for accurate data describing photonuclear reactions. The MT25 microtron operated at NPI was used for validation of cross section in the bremsstrahlung.

Characterization of the secondary neutron field inside a cyclotron for production of radiopharmaceuticals.

During production of radiopharmaceuticals, the radiation situation in cyclotron pit is an important parameter, which is being monitored to ensure fulfilment of the limits and conditions of safe operation. The neutron flux in the structural components of the accelerator is also an important parameter, because the secondary neutrons are responsible for activation of cyclotron structural components and may even affect structural changes in it. This paper aims to characterize the neutron field in inner positions of medical accelerator IBA 18/9 by activation detectors and by means of scintillation spectrometry.

MEASUREMENT OF PROMPT GAMMAS OF INELASTIC SCATTERING IN D2O SPHERE USING AMBE SOURCE.

The inelastic neutron scattering is often followed by the emission of gamma photon. As the prompt gammas have a discrete level character they can be used for the identification of nuclides. Because of this fact, a good knowledge of photon production from inelastic scattering is important.

Spectrum averaged cross section measurements of lutetium using standard Cf neutron source.

The spectrum averaged cross section (SACS) in a standard neutron field is a preferable tool for cross section validation. The presented work uses only neutron standard, i.e.

Testing of various neutron filters in reference neutron field in LR-0 reactor for nuclear data validation and verification.

Neutron activation analysis is the reference method used for offline determination of the neutron flux density in defined positions. It can be used in the nuclear energy industry-as well as in medical- or space applications. For accurate neutron flux evaluation, well-known and reliable cross sections are needed.

Measurement of very high threshold reactions using Cf source.

Only neutron spectrum standard is Cf spontaneous fission neutron spectrum. However, the high energy tail of this spectrum is loaded with high uncertainty. To reduce this uncertainty, it is crucial to use validated cross sections with low uncertainty.

Constraining high energy tail of U(n,f) prompt fission neutron spectrum.

There is a lack of reliable experiments aiming at the prompt fission neutron spectrum of U for energies higher than 10 MeV. The presented experiment performed at the LVR-15 light water reactor aimed at the measurement of very high threshold reactions spectral averaged cross sections such as Mn (n,2n)Mn, Au (n,2n)Au, Au (n,3n)Au, Bi(n,3n)Bi, Bi(n,4n)Bi. Bi(n,3n)Bi and Bi(n,4n)Bi reactions were measured for the first time.

INVESTIGATION OF NUCLEAR EMULSIONS IN TERMS OF NEUTRON DOSIMETRY.

Neutron detection using nuclear emulsions can offer an alternative in personal dosimetry. The production of emulsions and their quality have to be well controlled with respect to their application in dosimetry. Nuclear emulsions consist mainly of gelatin and silver halide.

Validation of IRDFF-II library by means of Cf spectral averaged cross sections.

Spectrum-averaged cross sections (SACS) is an important quantity usable in validation of nuclear cross sections. Especially in case of dosimetrical reactions there is a request on precise validation. This paper presents SACS measured in the reference Cf(sf) neutron field for neutron dosimetry reactions to validate recently updated IRDFF-II library intended mainly for neutron metrology applications.

Measurement of the selected spectral averaged cross sections in a radial channel of the VR-1 reactor.

The spectral averaged cross section is an important quantity used in a validation of nuclear cross section. When the cross sections are averaged over the neutron standard field (Cf(s,f) or U(n,f) neutron spectrum), they can be used for tuning of evaluations. This kind of quantities is very useful because the data in integral measurements can be determined with a significantly smaller uncertainties than the standard differential data.

Application of Cf neutron source for precise nuclear data experiments.

Purpose of this paper is to provide extensive information helpful for anyone performing any experiment involving Cf neutron source and aiming for high precision experiments. The paper summarizes basic characteristics and fields of study using Cf neutron source. We show the basic characteristics of our source, precise geometry in MCNP6, isotopic content, distribution of the source in the encapsulation and possible use of encapsulation for Al(n,2n)Al reaction estimation and the way of handling of the Cf neutron source in our laboratory.

Validation of selected (n,2n) dosimetry reactions in IRDFF-1.05 library.

Spectrum-averaged cross sections (SACS) have been measured in the reference Cf(sf) neutron field for the following high-threshold (n,2n) neutron dosimetry reactions since they are especially important due to the high threshold which allows validation of upper parts of prompt fission neutron spectrum. This work includes 59Co(n,2n)58Co, 197Au(n,2n)196Au, Tm(n,2n)Tm, Mn(n,2n)Mn, Nb(n,2n)Nb and Y(n,2n)Y and for the Co(n,p)Fe threshold reactions. SACS were inferred from experimentally determined reaction rates by gamma spectrometry using a semiconductor high-purity germanium detector to measure irradiated samples.

Measurements of neutron transport of well defined silicon filtered beam in lead.

The correct description of neutron transport in lead is an essential task for correct description of tritium production in the DEMO (DEMOnstration Power Station) breeding blanket because some concepts deal with lead as a major component: namely the WCLL (water cooled lithium lead blanket), HCLL (helium cooled lithium lead blanket), and DCLL (dual cooled lithium lead blanket). Concerning the improvement of the knowledge about the transport of fast neutrons in lead, a set of experiments and calculations was carried out to study this problem with a well-defined neutron beam. The neutron flux behind various lead arrangements positioned along the beam axis was measured using a stilbene scintillation crystal (10 mm × 10 mm) with neutron and gamma pulse shape discrimination.

The influence of core power distribution on neutron flux density behind a pressure vessel of a VVER-1000 Mock Up in LR-0 reactor.

The neutron flux distribution behind a reactor pressure vessel (RPV) is an important parameter that is monitored to determine neutron fluence in the RPV. Together with mechanical testing of surveillance specimens, these are the most important parts of in-service inspection programs that are essential for a realistic and reliable assessment of the RPV residual lifetime. The fast neutron fluence values are determined by a calculation.

Validation of nickel isotopes neutron cross sections using nickel spherical benchmark.

The fast leakage neutron spectra have been measured on spherical nickel benchmark assembly of diameter 50 cm. The Cf neutron source with approximate emission of 5.0·10 n/s was placed into the centre of the sphere.

On similarity of various reactor spectra and U prompt fission neutron spectrum.

A well-defined neutron spectrum is an essential tool not only for calibration and testing of neutron detectors used in dosimetry and spectroscopy but also for validation and verification of evaluated cross sections. A new evaluation of thermal-neutron induced U PFNS was performed by the International Atomic Energy Agency (IAEA) in the CIELO (Collaborative International Evaluated Library Organisation Project) project; new measurements of Spectral Averaged Cross sections averaged in the evaluated spectrum are to be obtained. In general, a neutron spectrum in the core is not identical to the pure fission one because fission neutrons undergo many scattering reactions, but it can be shown that PFNS and reactor spectra become undistinguishable from a certain energy boundary.

Disentangling the O cross section using light water and heavy water benchmark assemblies.

Fast neutron leakage spectra from the light and heavy water sphere of 30cm in diameter with neutron source in its centre were measured by a stilbene scintillation detector in the region of 1-10MeV in the distance of 85cm from the spheres surface. We use the light and heavy water to eliminate the effect of hydrogen. Cf with the approximate emission rate of 5.

Validation of differential cross sections by means of Cf spectral averaged cross sections.

The results of systematic evaluations of the spectrum-averaged cross section measurements performed in the spontaneous fission Cf neutron field are presented. The Following threshold reactions were investigated: Na(n,2n)Na, Fe(n,p)Mn, Fe(n,α) Cr, Al(n,p)Mg, Al(n,α)Na, F(n,2n)F, Zr(n,2n)Zr and Y(n,2n)Y. The spectrum-averaged cross sections for Na(n,2n)Na, Fe(n,α)Cr and Y(n,2n)Y reactions were measured for the first time.

Validation of zirconium isotopes (n,g) and (n,2n) cross sections in a comprehensive LR-0 reactor operative parameters set.

Zirconium is an important material used in most of reactor concepts for fuel cladding. Thus the knowledge of its cross section is important for reliable prediction of fuel operation. Also Zr(n,2n) reaction, is included in IRDFF files as dosimetry cross section standard.

On Fe neutron cross section importance in iron.

The presented paper aims to evaluate the importance of Fe XS in iron by means of measuring the reaction rates of the selected reactions on Fe and measuring a fast neutron leakage spectra from the iron sphere of 100cm in diameter by a stilbene scintillation detector with subsequent XS sensitivity analysis. The reactions involved in the study were Fe(n,p) and Fe(n,α). Measured neutron induced reaction rates in Fe are compared with calculated ones in different nuclear data libraries.

Measurement of neutron spectra in a silicon filtered neutron beam using stilbene detectors at the LVR-15 research reactor.

A well-defined neutron spectrum is an essential tool for calibration and tests of spectrometry and dosimetry detectors, and evaluation methods for spectra processing. Many of the nowadays used neutron standards are calibrated against a fission spectrum which has a rather smooth energy dependence. In recent time, at the LVR-15 research reactor in Rez, an alternative approach was tested for the needs of fast neutron spectrometry detector calibration.

Measurement and calculation of fast neutron and gamma spectra in well defined cores in LR-0 reactor.

A well-defined neutron spectrum is essential for many types of experimental topics and is also important for both calibration and testing of spectrometric and dosimetric detectors. Provided it is well described, such a spectrum can also be employed as a reference neutron field that is suitable for validating selected cross sections. The present paper aims to compare calculations and measurements of such a well-defined spectra in geometrically similar cores of the LR-0 reactor with fuel containing slightly different enrichments (2%, 3.