Fission products gamma dose from

Consider the doses at 1 km downwind, and compare them with corresponding doses from a release of 10 Ci of iodine-131 from a thermal reactor as listed in Table XII. For example, item 1 in Table XII, 40 rads gamma dose from the cloud of gases and volatiles, would be replaced by an item 2(X) rads gamma dose from the cloud of mixed fission products. Item 3, the inhalation dose to the child thyroid from iodine-131 in the cloud, would... 

To estimate the activity of 131I from the gamma dose requires knowledge of the relative activities of the other fission products. It can be assumed that the other isotopes of iodine (Fig. 3.1) will be present,... 

Fig. 3.8. Gamma dose rate from deposited fission products, normalised to initial deposit of 1 Bq m-2 of 131I. A, Instantaneous fission products B, reactor fission products C, volatile reactor fission products D, 131I only E, as measured at Munich after Chernobyl accident.

On 19 May 1953, a bomb of 32 kT yield (code name Harry) was exploded at the Nevada Test Site. A gamma dose rate equivalent to 27 milliroentgen per hour (230//Gy h 1) at 1 d was measured at St George, Utah, 200 km from the test site. Assuming no chemical fractionation of fission products, the fallout of 131I at St George was 1.0 MBq m 2. This is almost identical to the fallout of 1311 in the zone of maximum deposition about 10 km from Windscale (Chamberlain, 1959). Relative... 

The gamma and neutron flux is significantly reduced when the reactor is shut down and shielded by the reactor internals, reactor vessel, containment primary and secondary interior shield systems. Containment is accessible, but access is controlled. The dose rates in containment result from the residttal fission products and activated wear and corrosion products (see below) in the reactor coolant system. 

Exposure of the reactor unit personnel was associated mainly. with maintenance and repair work performed in the primary equipment rooms during reactor outages. Gamma-radiation dose rates in these rooms amounted to O.OS-0.4 pSv/s being defined by induced radioactivity of the primary sodium (Na-22). The contribution of fission products from leaky fuel rods did not exceed 15%. 

Sources of radiation in fresh fuel are plutonium isotopes, products of decay of the plutonium isotopes, and impurities of products of fission in the regenerated plutonium. As a result, the gamma and neutron radiation dose on a surface of fresh fuel bundles generated by fuel from weapon plutonium exceeds by more than an order of magnitude the appropriate dose capacity for FB from uranium fuel. Moreover, capacity of dose on a surface of FB with regenerated plutonium exceeds on an order of magnitude the dose capacity for FB with weapons plutonium. 

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