The What's New section keeps users informed of toxicity value changes, exposure parameter changes, chemical-specific parameter changes, and any equation format changes. Please check this site frequently to be advised of any recent changes.

October 2024

• A new BDCC output option was added, called peak BDCC, which calculates the activity of the parent radionuclide to be protective of the peak annual dose limit (DL) for the entire decay chain over time. For waste profiles that contain a refined radionuclide product with a relatively long half-life, the progeny may present more dose in the distant future than the parent in the present. By modeling the decay of the parent, with the ingrowth of all progeny, a protective peak BDCC can be calculated and used to compare against current monitoring or sample data for the protection of future receptors. Benefits of the peak BDCC are that future dates of peak dose are known. This knowledge helps make remedial decisions that are protective of future populations while reducing remediation costs, by not remediating a site where decay will reduce the dose naturally in a reasonable amount of time. Peak DCCs can also help design waste criteria and landfill caps protective of future dose. The peak BDCC output is discussed Section 2.2 "BDCC Output Options" of the User's Guide which discusses the other three BDCC output options. In the User's Guide there is a link to a technical report describing the development of this new BDCC output option.
• The new peak BDCC output option is now the preferred default BDCC option for use at Superfund sites.
• The Secular Equilibrium BDCC output option now presents the results on a mass basis in addition to activity.
• The dust BDCCs are now presented in disintegrations per minute (DPM) as well as pCi/cm². 1 pCi is equal to 2.22 DPM.
• The Radionuclide Decay Chain tool was added to the navigation box. This tool can predict the activity after a period of time (T) given a measurement of activity (A) for the chain parent.
• The hand to mouth exposure parameters and equations have been updated for the resident and indoor worker to reflect 2017 updates to Chapter 5 of the exposure factors handbook. A summary of the updated parameters are provided here.
• In site-specific mode for dust, a dropdown selection for site area was added that incorporates an Area Correction Factor (ACF_ext-gp). ACF values are derived in the Center for Radiation Protection Knowledge ACF report and presented in an appendix.
• Section 2.8 of the User's Guide has been added to describe some advanced uses of the calculator. Topics discussed are replicating old +D PRGs and postprocessing calculator results with a spreadsheet.
• The calculator will now allow selection of individual source depths when "3-D External Exposure" media is selected, rather than returning results for all five depths.
• A new FAQ was added explaining the application of Peak BDCCs with future maximum dose up to billions of years in the future.
• Instead of containing the calculator flow in a single browser tab, a new tab is opened for the site-specific page and the results page. This feature eliminates the need to reselect the radionuclides on the calculator main page and allows for site-specific parameters to be changed without losing data when using the back button. More details are presented in this FAQ.
• Deafult BDCC Generic Tables are now available.
• Numerous labels, references, and exposure route descriptions in the user's guide were enhanced for clarity.

November 2020

• A units conversion discrepancy was corrected for the submersion dose coefficients.

May 2018

• While running the user provided option in site-specific mode, the calculator was showing duplicate records for C, H, Hg, I, Ni, Ru, S, and Te elemental isotopes. These duplicate records have been removed.

July 2017

• When the secular equilibrium BDCC output option is selected, the BDCC Calculator now gives the option to show the individual progeny contributions for the BDCC (and dose) output.

May 2017

• The +D and +E isotopes have been removed from the selection list. Now, a user may select the 'Assume secular equilibrium' to see PRG output for the entire chain.

January 2017

• New inhalation Risk and Dose Coefficients are avilable for Rn-222, Rn-220, Bi-212, Bi-214, Pb-212, Pb-214, and Po-218.

September 2015

• New dose coefficients (DCFs) have been derived following FGR 12 and 13 and using the updated isotope list from ICRP 107. DCFs used are provided by the Center for Radiation Protection Knowledge. The main report is Calculations of Slope Factors and Dose Coefficients, and the tables of DCFs are in a separate appendix.
• A forward dose assessment option was added to the calculator page. By selecting this option, the user is asked for media concentrations, and the dose is returned using BDCC equation inputs.
• The radionuclide decay chains, provided in the calculator output, have been updated to reflect new decay information from ICRP 107. In addition to tabular results, a visual diagram depicts the branching fractions.
• Updated F_SURF values were added that account for multiple source depths (ground plane, 1cm, 5cm, 15cm, and infinite depth) and multiple building materials (wood, glass, concrete, drywall, and adobe mud brick were analyzed as well as 2 composite scenarios). Composite 1 is a drywall room with a glass window, wooden doors, and drywall walls. The floors for composite 1 are concrete, and the ceiling is drywall. Composite 2 is a concrete room with wooden doors, a drywall ceiling, and a concrete floor. Both composite cases used a homogeneous mix of material for the walls to represent the window and door mixed in with the wall. Finklea 2015 presents the analysis. See Section 4.3.10 of the User Guide for more details.

September 2014

• This calculator follows OSWER Directive recommendations for use of exposure parameters from the 2011 Exposure Factors Handbook.

March 2011

New generic tables are now available that address the issues listed in the previous entry.

August 2010

Many updates were performed to establish consistency with other calculators. These updates are mainly in appearance and in functionality. Area Correction Factor defaults have changed slightly, and new generic tables will be available soon.