Packaging Certification program Methodology for Determining Dose Rates for Small Gram Quantities in Shipping Packagings

Conference · Wed May 09 00:00:00 EDT 2012

OSTI ID:1039987

Nathan, Steven J. ^[1]; Loftin, Bradely M. ^[2]; Abramczyk, Glenn A. ^[2]; Bellamy, John S. ^[2]

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1. Savannah River Nuclear Solutions (SRNS), Aiken, SC (United States)
2. Savannah River National Laboratory (SRNL), Aiken, SC (United States)

The Small Gram Quantity (SGQ) concept is based on the understanding that small amounts of hazardous materials, in this case radioactive materials (RAM), are significantly less hazardous than large amounts of the same materials. This paper describes a methodology designed to estimate an SGQ for several neutron and gamma emitting isotopes that can be shipped in a package compliant with 10 CFR Part 71 external radiation level limits regulations. These regulations require packaging for the shipment of radioactive materials, under both normal and accident conditions, to perform the essential functions of material containment, subcriticality, and maintain external radiation levels within the specified limits. By placing the contents in a helium leak-tight containment vessel, and limiting the mass to ensure subcriticality, the first two essential functions are readily met. Some isotopes emit sufficiently strong photon radiation that small amounts of material can yield a large dose rate outside the package. Quantifying the dose rate for a proposed content is a challenging issue for the SGQ approach. It is essential to quantify external radiation levels from several common gamma and neutron sources that can be safely placed in a specific packaging, to ensure compliance with federal regulations. The Packaging Certification Program (PCP) Methodology for Determining Dose Rate for Small Gram Quantities in Shipping Packagings provides bounding shielding calculations that define mass limits compliant with 10 CFR 71.47 for a set of proposed SGQ isotopes. The approach is based on energy superposition with dose response calculated for a set of spectral groups for a baseline physical packaging configuration. The methodology includes using the MCNP radiation transport code to evaluate a family of neutron and photon spectral groups using the 9977 shipping package and its associated shielded containers as the base case. This results in a set of multipliers for 'dose per particle' for each spectral group. For a given isotope, the source spectrum is folded with the response for each group. The summed contribution from all isotopes determines the total dose from the RAM in the container.

• Research Organization: Savannah River Site (SRS), Aiken, SC (United States); Savannah River National Laboratory (SRNL), Aiken, SC (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC09-08SR22470
• OSTI ID: 1039987
• Report Number(s): SRNS-STI-2012-00285; TRN: US1202290
• Resource Relation: Conference: 53. INMM Annual Meeting, Orlando, FL (United States), 15-19 Jul 2012
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
42 ENGINEERING
ACCIDENTS
COMPLIANCE
CONFIGURATION
CONTAINERS
CONTAINMENT
CRITICALITY
DOSE RATES
HAZARDOUS MATERIALS
HELIUM
NEUTRON SOURCES
NEUTRONS
PACKAGING
PHOTONS
RADIATION TRANSPORT
RADIATIONS
RADIOACTIVE MATERIALS
REGULATIONS
SHIELDING
Nuclear Criticality Safety Program (NCSP)
Small Gram Quantity (SGQ)
Radioactive Materials (RAM)
Packaging Certification Program (PCP)
MCNP