Intent of the QA Testing of Respirator HEPA Filters, as Discussed in NUREG-0041
See the letter from L. J. Cunningham to S. K. Herweyer (TSI Incorporated) dated February 27, 1990.
Aerosol penetration testing of filters or canisters should be performed with a testing protocol that is capable of detecting significant filter damage or deterioration. It is not necessary, nor is it required, to recertify the filter as HEPA prior to use.
The health physics position was written in the context of 10 CFR 20.103, but it also applies to "new" 10 CFR 20.1703 Confirmation was asked whether the intent of the Quality Assurance Testing of respirator high efficiency particulate (HEPA) filters discussed in NUREG-0041 was that they be tested to meet the NIOSH certification protocols. This is not the case. The NRC does not require the recertification of HEPA filters prior to use.
10 CFR 20.103 (c) requires that "when respirator protective equipment is used to limit the inhalation of airborne radioactive material ... the licensee shall use equipment that is certified or had certification extended by ... NIOSH / MSHA." [Note: 10 CFR 20.1703 (a) requires that "the licensee shall use only respiratory protection equipment that is tested and certified or had certification extended by ... NIOSH / MSHA."] This requirement is echoed in Appendix A, Footnote (b) to 10 CFR 20 [and Footnote d.2 (b) of Appendix A to 10 CFR Part 20 (§§20.1001-20.2401)] which indicates that the protection factors listed for air-purifying respirators are valid only when the "high efficiency particulate filters (above 99.97% removal efficiency by thermally generated 0.3 micro-m dioctyl phthalate [DOP] test or equivalent)" are used.
Use of non HEPA filters would be outside the NIOSH / MSHA certification. Respirator filter manufacturers have quality assurance (QA) and quality control (QC) programs approved by NIOSH to ensure that their HEPA filters or cartridges meet the certification criteria referred to in the Appendix A footnote. The QA program discussed in NUREG-0041 is provided to assure that this certification has not been voided by deterioration or damage. Aerosol penetration testing of filters prior to their reuse is necessary to detect damage, incurred by prior use, that may not be evident with a visual or pressure drop test.
In 1983, responding to a question regarding the acceptance criteria for filter QA testing by our licensees, the NRC Office of Research (RES) took the position that respirator filters had to be tested with a 0.3 micron, thermally generated DOP aerosol. This defaulting to the HEPA filter certification criteria was a conservative position taken due to a lack of data on other test methods.
Since that time, however, filter testing protocols with other aerosol media and/or generating techniques has been shown to provide adequate sensitivity to detect damage to a filter which would void its HEPA characteristics. Therefore, it is the current position that aerosol penetration testing of filters and canisters by licensees should be performed with a testing protocol capable of detecting significant filter damage or deterioration. It is not necessary, nor is it required, to recertify the filter as HEPA prior to use.
Regulatory references: 10 CFR 20.103, 10 CFR 20.1703, NUREG-0041
Subject codes: 8.10