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Impact of the Revision of 10CFR835 with Regard to Neutron Field Surveys

Veinot, K G.*

doi: 10.1097/01.HP.0000318884.84365.81
Articles: Operational Topic
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The compliance requirements for Department of Energy facilities are codified in Title 10 Code of Federal Regulations Part 835. The regulation was recently revised to adopt the 1990 Recommendations of the International Commission on Radiological Protection (ICRP). Although the impacts of this change include areas other than neutron dosimetry, the intent of this text is to outline the new regulation’s effect on neutron instrument calibrations and field surveys. A significant change as a result of the adoption of the ICRP 60 recommendations is the change in the quality factor applied to operational quantities including the quantity used for area monitoring and instrument calibrations, notably the ambient dose equivalent, H*(d). Since the definitions of the operational quantities were not changed, the absorbed dose values for these quantities remain consistent with previous recommendations so the only adjustment necessary is to account for the revised quality factors. For this work, commonly encountered neutron spectra were folded with energy dependent conversion coefficients, h*(10)(E), determined using the old and new quality factors to compute conversion coefficients for the various sources. Additionally, the effect on a single point calibration for the widely used “Rem ball” is discussed. In general, the change in conversion coefficients under the newer guidelines results in a 5 to 15% increase in H*(10), which will require modifications to instrument calibrations.

* Y-12 National Security Complex, PO Box 2009, MS 8105, Oak Ridge, TN 37831-8105.

The general effects on neutron field surveys as a result of the adoption of the ICRP 60 recommendations in the recently revised 10CFR835 are discussed.

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