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The evaluated spectroscopic data are presented for known nuclides of mass 228 (Ac, At, Fr, Np, Pa, Pu, Ra, Rn, Th, and U). Excited states in {sup 228}At, {sup 228}Rn, {sup 228}Fr, {sup 228}Np, and {sup 228}Pu have not been identified as yet. Significant amounts of new data have been added since the last evaluation of A=228 nuclides. This work supersedes earlier full evaluations of A=228 published by 1997Ar08.
In this study effective radium content and radon exhalation rates in soil samples collected from Adapazarı district of Sakarya, Turkey have been measured using LR-115 type-II plastic track detectors by closed-can technique for the first time. The obtained effective radium contents are found to vary from 6.66 to 34.32 Bqkg{sup −1} with a mean value of 18.01 Bqkg{sup −1}. The radon exhalation rates measured in terms of mass and area of soil samples are found to vary from 50.35-259.41 mBqkg{sup −1}h{sup −1} with a mean value of 136.12 mBqkg{sup −1}h{sup −1} and 1035.18-5333.39 mBqm{sup −2}h{sup −1} with a mean value of mBqm{sup −2}h{sup −1}. All the measurements show that the values of radium content are under the safe limit recommended by Organization for Cooperation and Development.
One example special case for Final Status Surveys (FSSs) occurs at Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA) sites at which the radioactive materials are from the processing of uranium or thorium ores for their source material content. At these sites, EPA's Health and Environmental Protection Standards for Uranium and Thorium Mill Tailings, in 40 CFR 192, are applicable. Also, 40 CFR 192 may be invoked at non-UMTRCA sites through the CERCLA as an Applicable or Relevant and Appropriate Requirement (ARAR) due to the presence of radium (Ra)-226 or Ra-228, even though the source of residual radioactive material was not a uranium or thorium mill tailings facility. However, the regulatory requirements in these standards infringe on some of the recommendations in the Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM). Specifically, the soil cleanup standards for Ra-226 or Ra-228 are specified as averages over an area of 100 square meters (m{sup 2}). Note that in the 40 CFR 192 rulemaking, an averaging area of 100 m{sup 2} was used as a reasonable footprint for a home. One goal of the 40 CFR 192 standards was to protect future homes from indoor radon, and the specified averaging area was a component implemented for the protection of health. In addition, 40 CFR 192 is silent regarding elevated measurement criteria (EMC)-type requirements for smaller areas of elevated radioactive material within the 100-m{sup 2} footprint. At UMTRCA sites and CERCLA sites where UMTRCA is an ARAR, the following approach for FSSs is acceptable: - Survey units (SUs) may be classified, as appropriate, and survey activities may be adjusted accordingly for Class 1, Class 2, or Class 3 SUs. - Class 1 soil SUs should provide for evaluation of portions that are no greater than 100 m{sup 2} in size, consistent with the 40 CFR 192 standards. - Class 2 and 3 soil SUs are not expected to exceed the 40 CFR 192 soil cleanup standard, so they do not require evaluation of portions that are no greater than 100 m{sup 2} in size. - Compliance with 40 CFR 192 can be demonstrated through analysis of soil samples or composite soil samples from each SU, in conjunction with gamma radiation scanning or in situ gamma radiation measurements of each SU. When appropriate, these gamma radiation scans or in situ measurements correlated to soil sampling may be used in place of soil sampling. - By demonstrating that the average over 100 m{sup 2} meets the 40 CFR 192 soil cleanup standard, the EMC criteria for small elevated areas of activity are not required for the purposes of MARSSIM, but may be developed. These minor modifications to the standard MARSSIM radiological survey approach are acceptable for UMTRCA sites or CERCLA sites where UMTRCA is an ARAR. (authors)
The experimental nuclear spectroscopic data for ten experimentally known nuclides of mass number 224 (Bi, Po, At, Rn, Fr, Ra, Ac, Th, Pa, U) have been evaluated and presented together with the Adopted properties for levels and γ rays. For {sup 224}Bi, {sup 224}Po, {sup 224}At, {sup 224}Rn, {sup 224}Fr, {sup 224}Pa and {sup 224}U nuclei, only the ground–state information is known. Half–lives of ground states of 224Bi and 224Po have not yet been measured. The decay of {sup 224}Rn to {sup 224}Fr has been studied, but no decay scheme has been proposed. The decay of {sup 224}Ac to {sup 224}Ra is reported only in an abstract style conference proceedings. For a definite Jπ assignment for ground state of {sup 224}Ac, a detailed study of this decay may be helpful. In the decay of {sup 228}Pa to {sup 224}Ac, authors of 1994Ah03 state that the lowest state observed in their work may not be the ground state. Thus an extensive study of {sup 228}Pa α decay, and studies involving nuclear reactions are warranted since the level scheme of {sup 224}Ac presented in this evaluation is considered as incomplete due to the lack of confirmed information about multipolarities, mixing ratios and other spectroscopic details. Three new nuclides {sup 224}Bi, {sup 224}Po, and {sup 224}At are added in this revision, together with new in–beam γ–ray and Coulomb excitation data for {sup 224}Ra. Although, not much new experimental data have appeared since the previous evaluation (1997Ar05), extensive modifications have been made in almost all the datasets. This work supersedes the information presented in the previous NDS evaluations of A = 224: 1997Ar05, 1986Ma45 and 1976El05.
Fluxes and exchange coefficients are derived for the transport of Sr-90, Pb-210, Bi-210, and Po-210 between the free troposphere and the marine boundary layer and between the boundary layer and the sea surface. Radionuclide concentrations previously measured near Hawaii are used in the derivations. Values obtained for the free troposphere/boundary layer exchange coefficient (expressed as a piston velocity) were 185, 228 and 203 m/d for Pb-210, Bi-210, and Sr-90, respectively. The magnitude of the local sea-surface source of Po-210 is also determined.