15A NCAC 11 .1617 ACCESS TO VERY HIGH RADIATION AREAS: IRRADIATORS
(a) Each area in which there may exist radiation levels in excess of 500 rads (5 grays) in one hour at one meter from a source of radiation that is used to irradiate materials shall meet the following requirements:
(1) Each entrance or access point shall be equipped with entry control devices which:
(A) function automatically to prevent any individual from inadvertently entering the area when very high radiation levels exist;
(B) 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 0.1 rem (1 mSv) in one hour; and
(C) prevent operation of the source of radiation if the source would produce radiation levels in the area that could result in a deep-dose equivalent to an individual in excess of 0.1 rem (1 mSv) in one hour.
(2) Additional control devices shall be provided so that, upon failure of the entry control devices to function as required by Subparagraph (a)(1) of this Rule:
(A) 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 0.1 rem (1 mSv) in one hour; and
(B) 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.
(3) The licensee or registrant shall provide control devices so that, upon failure or removal of physical radiation barriers other than the shielded storage container:
(A) 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 0.1 rem (1 mSv) in one hour; and
(B) 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.
(4) When the shield for the stored source of radiation is a liquid, the licensee or registrant shall provide means to monitor the integrity of the shield and to signal, automatically, loss of adequate shielding.
(5) Physical radiation barriers that comprise permanent structural components, such as walls, that have no credible probability of failure or removal in ordinary circumstances need not meet the requirements of Subparagraphs (a)(3) and (4) of this Rule.
(6) Each area shall be equipped with a clearly identified control device which can prevent the source of radiation from being put into operation.
(7) Each area shall 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 sufficient time for any individual in the area to operate the control device required by Subparagraph (a)(6) of this Rule.
(8) Each area shall 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.
(9) Each area shall 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 in the area is below that at which it would be possible for an individual to receive a deep-dose equivalent in excess of 0.1 rem (1 mSv) in one hour.
(10) The entry control devices required in Subparagraph (a)(1) of this Rule shall have been tested for proper functioning. Recordkeeping requirements relating to these tests are provided in Rule .1643 of this Section.
(A) Testing shall be conducted prior to initial operation of the source of radiation on any day, unless operations were continued uninterrupted from the previous day;
(B) Testing shall be conducted prior to resumption of operation of the source of radiation after any unintended interruption; and
(C) The licensee or registrant shall submit and adhere to a schedule for periodic tests of the entry control and warning systems.
(11) The licensee or registrant shall 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.
(12) 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, shall 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. Exit portals for processed materials shall be equipped to detect and signal the presence of any loose radiation sources that are carried toward such an exit and to automatically prevent loose radiation sources from being carried out of the area.
(b) Any licensee, registrant or applicant for a license or registration for sources of radiation that are subject to Paragraph (a) of this Rule and that will be used in a variety of positions or in locations, such as open fields or forests, that make it impracticable to comply with certain requirements of Paragraph (a) of this Rule, such as those for the automatic control of radiation levels, may apply to the agency for approval of the use of alternative safety measures. Any alternative safety measures shall provide a degree of personnel protection at least equivalent to those specified in Paragraph (a) of this Rule. At least one of the alternative measures shall include an entry-preventing 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 radiation sources are used.
(c) The entry control devices required by Paragraphs (a) and (b) of this Rule shall be established in such a way that no individual will be prevented from leaving the area.
(d) This Rule applies to radiation from non-self-shielded irradiators. This Rule does not apply to sources of radiation that are used in therapy, in 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. This Rule also does not apply to sources of radiation from which the radiation is incidental to some other use.
History Note: Authority G.S. 104E-7(a)(2);
Eff. January 1, 1994.