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 "operational, conditional, or preliminary" clearance, pending the analysis and availability of Rockbridge data (Reference C.9.185, pp. 50 through 52).

Results of the assay of fission products and plutonium on Rockbridge were available on 25 October 1946 from the University of California. At the time of the collection of the samples, radsafe monitors reported the external hull readings were 0.009 to 0.010 R/24 hours (beta plus gamma). The total activity calculated to be present on Rockbridge was 376 millicuries of fission product activity and 2.020 milligrams of plutonium. This material was distributed inside 23.207 ft² (2.16 km²) of saltwater piping, inside 12.780 ft² (1.18 km²) of condenser and evaporator interiors, and the entire underwater hull The hull contamination when removed was contained in the 125 tons of sand used to sandblast the external hull. Although about two tolerance doses of plutonium were detected, these and the fission products were spread over an extremely large area and in locations that greatly reduced the potential exposure to personnel (Reference C.11.18; Reference C.9.185, p. 56).

In addition to continuing uncertainty about final clearance standards, the decontamination regulations promulgated up to that time had two gaps: (1) how to determine contamination of a ship's hull without time-consuming and expensive drydocking, and (2) how to remove contamination from condensers. At that point BuMed appointed a special medical board to advise the Navy's Surgeon General, who was Chief of BuMed, on radiological matters presented to it for study. It was chaired by the Medical officer dispatched to San Francisco in late August by CJTF 1 and included the Radsafe advisor to CJTF 1 and radiation experts from the University of California (Reference C.9.185, p. 54).

The medical board held its first general meeting on 4 November to consider results of analysis of Rockbridge samples. After much discussion, the members of the board suggested a set of final clearance standards, but these were not acceptable either to BuMed or BuShips. BuShips sent a representative to the west coast, and after consultation with the BuShips representative and additional study, the board proposed a new set of final radiological clearance standards as follows (Reference C.9.185, p. 56):


 * 1. Habitually closed saltwater systems were not to have exterior readings exceeding:


 * a. 0.001 R/24 hours (gamma) for 94 percent of the system


 * b. 0.005 R/24 hours (gamma) for 5 percent of the system


 * c. 0.01 R/24 hours (gamma) for 1 percent of the system.


 * 2. Open systems were not to exceed an average of 0.001 R/24 hours (gamma) and 0.005 R/24 hours (gamma plus beta)


 * 3. Underwater portions of the hull exposed by listing and trimming were not to exceed an average of 0.02 R/24 hours (gamma plus beta) wet or dry.

BuShips accepted these standards for final clearance. For operational or preliminary clearance, the bureau took the standards the board had originally set for active ships, namely (Reference C.9.185, pp. 54 and 55):

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