Updated neutron spectrum characterization of SNL baseline reactor environments. Volume 1, Characterization

Griffin, Patrick J.; Kelly, J.G.; Vehar, David W.

doi:10.2172/10145322

Cited by 26 publications

(16 citation statements)

References 7 publications

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“…The neutron energy spectrum in the central cavity is perturbed by the presence of test objects located in the cavity. All calculations described in this report assumed that the neutron energy spectrum external to the sphere was the ACF9 spectrum [4] and was thus unaffected by any perturbations caused by the test object.…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, an MCNP (Monte Carlo NParticle Transport Code) [2] and/or MCNPX (Monte Carlo N-Particle eXtended Transport Code) [3] model of the spheres was/were created and used for comparison to the experimental results. The model uses a 640-group representation of the ACF9 neutron energy spectrum [4]. The MCNP/MCNPX model is found in Appendix A.…”

Section: Acronyms and Abbreviationsmentioning

confidence: 99%

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Experiment summary for n/y attenuation through materials (Environments 1A).

DePriest¹

2006

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The Radiation Effects Sciences (RES) program is responsible for conducting Neutron Gamma Energy Transport (NuGET) code validation. In support of this task, a series of experiments were conducted in the annular core research reactor (ACRR) to investigate the modification of the incident neutron/gamma environment by aluminum (Al6061) and high-density polyethylene (HDPE) spheres with 4-in and 7-in-diameter. The experiment series described in this report addresses several NuGET validation concerns. The validation experiment series also addresses the design and execution of proper reactor testing to match the hostile radiation environments and to match the component stresses that arise from the hostile radiation environments. This report summarizes the RES Validation: n/γ Attenuation through Materials, Environments 1A, experiments conducted at the ACRR in

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Section: Discussionmentioning

confidence: 99%

Section: Acronyms and Abbreviationsmentioning

confidence: 99%

Experiment summary for n/y attenuation through materials (Environments 1A).

DePriest¹

2006

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“…The value of Q for an event is obtained by integrating the signal current (I n (t)), but the value of n requires additional passive dosimetry. Initially, the average neutron fluence was estimated using a detailed ACRR model in MCNP [2], based off of SAND report values for the LB36 environment [3,4]. The estimate of the neutron fluence was refined and/or corrected through the use of appropriate dosimetry monitor foils as shown in Fig.…”

Section: Evaluation Of Calibration Technique In Acrr Lb36 Environmentmentioning

confidence: 99%

Modeling, Calibration, and Verification of a Fission Chamber for ACRR Experimenters

Coburn

Luker

Parma

et al. 2016

EPJ Web of Conferences

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Abstract.When performing research at a reactor facility, experimenters often need to determine the neutron fluence achieved during an operation. Facilities typically provide guidance in the form of neutron fluence per megajoule (MJ) or through passive dosimetry results. After experiment completion, there is sometimes a delay of several days (or weeks) before the passive dosimetry results are available. In the interim, an experimenter does not have confirmation that the desired irradiation levels were reached. Active dosimetry may provide an estimate of neutron fluxes, but few active detectors are available that have been calibrated to measure neutron fluxes obtained inside the Annular Core Research Reactor (ACRR) central cavity environment. For past experiments at the ACRR, the neutron fluence was calculated by integrating the response of a fission chamber rate detection signal and then normalizing this integral to fluence determined from passive dosimetry. An alternative method of directly measuring neutron flux is desired; the new methodology described provides a complete neutron flux profile after a reactor pulse, utilizing fission chamber physics in combination with a compensating ion chamber to extract and convert a current signal to neutron flux as a function of time.

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“…The neutron spectrum found in the "empty" ACRR-Central Cavity has been determined by the SNL-Radiation Metrology Laboratory (SNLRML) using spectrum unfold techniques [Gr94]. The "empty" configuration is the central cavity with an aluminum experiment bucket with the SNLRML dosimetry fixture inside sitting on top of the 32" + 8" pedestals.…”

Section: Acrr-central Cavity Neutron Spectrummentioning

confidence: 99%

“…The neutron spectrum found in the Pb-B 4 C spectrum-modifying bucket was also determined by the SNLRML using spectrum unfold techniques [Gr94]. This configuration is the Pb-B 4 C spectrum-modifying bucket on the 32" + 8" pedestals with a SNLRML dosimetry fixture inside.…”

Section: Pb-b 4 C Spectrum-modifying Bucket Neutron Spectrummentioning

confidence: 99%

MCNP/MCNPX model of the annular core research reactor.

DePriest¹,

Cooper²,

Parma³

2006

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Many experimenters at the Annular Core Research Reactor (ACRR) have a need to predict the neutron/gamma environment prior to testing. In some cases, the neutron/gamma environment is needed to understand the test results after the completion of an experiment. In an effort to satisfy the needs of experimenters, a model of the ACRR was developed for use with the Monte Carlo N-Particle transport codes MCNP [Br03] and MCNPX [Wa02]. The model contains adjustable safety, transient, and control rods, several of the available spectrum-modifying cavity inserts, and placeholders for experiment packages. The ACRR model was constructed such that experiment package models can be easily placed in the reactor after being developed as stand-alone units. An addition to the "standard" model allows the FREC-II cavity to be included in the calculations. This report presents the MCNP/MCNPX model of the ACRR. Comparisons are made between the model and the reactor for various configurations. Reactivity worth curves for the various reactor configurations are presented. Examples of reactivity worth calculations for a few experiment packages are presented along with the measured reactivity worth from the reactor test of the experiment packages. Finally, calculated neutron/gamma spectra are presented.4

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Updated neutron spectrum characterization of SNL baseline reactor environments. Volume 1, Characterization

Cited by 26 publications

References 7 publications

Experiment summary for n/y attenuation through materials (Environments 1A).

Experiment summary for n/y attenuation through materials (Environments 1A).

Modeling, Calibration, and Verification of a Fission Chamber for ACRR Experimenters

MCNP/MCNPX model of the annular core research reactor.

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