Section 180-4-025 - CONTROL OF ACCESS TO VERY HIGH RADIATION AREAS-IRRADIATORSThe requirements for control of access to very high radiation areas at non-self-shielded irradiators are as follows.
025.01NON-SELF-SHIELDED IRRADIATORS. 180 NAC 4-025 applies to licensees or registrants with sources of radiation in non-self-shielded irradiators. 180 NAC 4-025 does not apply to sources of radiation that are used in teletherapy, in industrial radiography, or in completely self-shielded irradiators in which the source of radiation is both stored and operated within the same shielding radiation barrier and, in the designed configuration of the irradiator, is always physically inaccessible to any individual and cannot create high levels of radiation in an area that is accessible to any individual.025.02AREA CONTROLS. Each area in which there may exist radiation levels in excess of 5 Gy (500 rad) in 1 hour at 1 meter from a source of radiation that is used to irradiate materials must meet the following requirements. 025.02(A)ENTRANCE OR ACCESS POINT. Each entrance or access point must be equipped with entry control devices that: (i) Function automatically to prevent any individual from inadvertently entering a very high radiation area;(ii) Permit deliberate entry into the area only after a control device is actuated that causes the radiation level within the area, from the source of radiation, to be reduced below that at which it would be possible for an individual to receive a deep dose equivalent in excess of 1 mSv ( 0.1 rem) in 1 hour; and(iii) Prevent operation of the source of radiation if it would produce radiation levels in the area that could result in a deep dose equivalent to an individual in excess of 1 mSv ( 0.1 rem) in 1 hour.025.02(B)ADDITIONAL CONTROL DEVICES. Be provided with additional control devices upon failure of the entry control devices to function as required by 180 NAC 4-025.02(A): (i) The radiation level within the area, from the source of radiation, is reduced below that at which it would be possible for an individual to receive a deep dose equivalent in excess of 1 mSv ( 0.1 rem) in 1 hour; and(ii) Conspicuous visible and audible alarm signals are generated to make an individual attempting to enter the area aware of the hazard and at least one other authorized individual, who is physically present, familiar with the activity, and prepared to render or summon assistance, aware of the failure of the entry control devices.025.02(C)FAILURE OR REMOVAL OF PHYSICAL RADIATION BARRIERS. The licensee or registrant must provide control devices so that, upon failure or removal of physical radiation barriers: (i) The radiation level from the source of radiation is reduced below that at which it would be possible for an individual to receive a deep dose equivalent in excess of 1 mSv ( 0.1 rem) in 1 hour; and(ii) Conspicuous visible and audible alarm signals are generated to make potentially affected individuals aware of the hazard and the licensee or registrant or at least one other individual, who is familiar with the activity and prepared to render or summon assistance, aware of the failure or removal of the physical barrier.025.02(D)PERMANENT STRUCTURAL COMPONENTS. Physical radiation barriers that comprise permanent structural components or walls that have no credible probability of failure or removal in ordinary circumstances need not meet the requirements of 180 NAC 4-025.02(C).025.02(E)VISIBLE AND AUDIBLE ALARMS. Each area must be equipped with devices that will automatically generate conspicuous visible and audible alarm signals to alert personnel in the area before the source of radiation can be put into operation and in time for any individual in the area to operate a clearly identified control device, which must be installed in the area and which can prevent the source of radiation from being put into operation.025.02(F)AREA CONTROLS. Each area must be controlled by use of such administrative procedures and such devices as are necessary to ensure that the area is cleared of personnel prior to each use of the source of radiation.025.02(G) RADIATION MEASUREMENT. Each area must be checked by a radiation measurement to ensure that, prior to the first individual's entry into the area after any use of the source of radiation, the radiation level from the source of radiation in the area is below that at which it would be possible for an individual to receive a deep dose equivalent in excess of 1 mSv ( 0.1 rem) in 1 hour.025.02(H)ENTRY CONTROL DEVICE TESTING. The entry control devices required in 180 NAC 4-025.02(A), must have been tested for proper functioning: (i) Testing must be conducted prior to initial operation with the source of radiation on any day, unless operations were continued uninterrupted from the previous day;(ii) Testing must be conducted prior to resumption of operation of the source of radiation after any unintentional interruption; and(iii) The licensee or registrant must submit and adhere to a schedule for periodic tests of the entry control and warning systems.025.02(I)FUNCTIONING CONTROL DEVICES. The licensee or registrant must not conduct operations, other than those necessary to place the source of radiation in safe condition or to effect repairs on controls, unless control devices are functioning properly.025.02(J) ENTRY AND EXIT PORTALS. Entry and exit portals that are used in transporting materials to and from the irradiation area, and that are not intended for use by individuals, must be controlled by such devices and administrative procedures as are necessary to physically protect and warn against inadvertent entry by any individual through these portals.025.03ALTERNATIVE SAFETY MEASURES. Registrants or applicants for registrations for sources of radiation within the scope of 180 NAC 4-025.02 that will be used in a variety of positions or in locations that make it impracticable to comply with certain requirements of 180 NAC 4-025.02, may apply to the Department for approval of alternative safety measures. Alternative safety measures must provide personnel protection at least equivalent to those specified in 180 NAC 4-025.02. At least one of the alternative measures must include an entrypreventing interlock control based on a measurement of the radiation that ensures the absence of high radiation levels before an individual can gain access to the area where such sources of radiation are used.025.04ENTRY CONTROL DEVICES. The entry control devices required by 180 NAC 4025.02 and 4-025.03 must be established in such a way that no individual will be prevented from leaving the area.180 Neb. Admin. Code, ch. 4, § 025
Amended effective 6/7/2021