RADIATION PROTECTION WITHIN A STANDARD HOUSING STRUCTURE By Rosert T. Graveson Health and Safety Laboratory New York Operations Office, U. 8. Atomic Energy Commission INTRODUCTION The gamma radiation ficld measured at a point above a contaminated area is the sum of fallout. 10 is believed that the roof bad been either partially, or completely, cleaned by the rain action. the individual radiation contributions from incremental surface areas located at various distances from the observer. A_ relatively small, clean area may be expected to reduce the total intensity by eliminating the close-in con- tribution. In practical application, a building which does not offer shielding by its walls will still reduce the total dose to an observer duc to the existence of this clean area, although the roof may carryactivity. Relatively uniform fallout contamination was present in the vicinity of a one-story build- ing. The gamma measurements made inside this building indicated that an appreciable reduction in radiation intensity may be expected within standard housing structures. All measurements were made with a scintillation detector, HASL Type TH-3-C. This unit uses a sodium iodide crystal which has a nonlinear energy response, Figure 2, and is not roentgen equivalent. PROCEDURES The building in Figure 1 is located on a level field. It is located 50 feet from an adjacent building, and its back faces a small earth mound situated 20 feat from the rear wall. The build- ing was constructed of corrugated aluminum siding, approximately %2-inch thick on a con- crete slab floor, Two sides are bordered by a porch. The gamma radiation field in the vicinity resulted from fallout, and the measurements were made 6 days after the shot. Ficure 1.—Location of Building. A lotal of 2 inches of rain had fallen in several hard showers subsequent to the cessation of active However, the readings were all made within a short time interval, climinating energy dependence on the changing gamme ray spectra of the fission products. DISCUSSION The radiation readings, at 3.6 feet from the surface, were plotted on a plan view of the building, Figure 3. Readings were takenin the open doorways and behind the adjacentwalls, and indicate that there was little effective wall absorption. The section through the building, Figure 4, shows that the outside activity ap- pears constant except in the vicinity of a rain ditch where a sharp increase is noted. 13 ~— The distribution of readings across the open porch