Information Notice No. 84-60: Failure of Air-purifying Respirator Filter to Meet Efficiency Requirement
SSINS No.: 6835
IN 84-60
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
August 6, 1984
Information Notice No. 84-60: FAILURE OF AIR-PURIFYING RESPIRATOR
FILTER TO MEET EFFICIENCY REQUIREMENT
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP), research and test reactors, and fuel facilities.
This information notice provides notification of the failure of a small
percentage of Mine Safety Appliances (MSA) Company's Ultra Filters used in
negative-pressure respirators and filters used in positive-pressure
air-purifying respirators (PAPRs), part numbers 464807 and 463284,
respectively. This small percentage (overall less than 5%) failed to meet
the National Institute of Occupational Safety and Health/Mine Safety and
Health Administration (NIOSH/MSHA) certification requirement in 30 CFR 11
that high efficiency filters be at least 99.97% efficient against a
thermally generated, monodisperse 0.3 micron aerosol of dioctyl phthalate.
The MSA has taken steps that NIOSH considers adequate to resolve this
problem. It is expected that addressees will review the information provided
for applicability to their respiratory programs. Guidance and suggestions
contained in this notice do not constitute NRC requirements and, therefore,
no specific action or written response is required.
Description of Circumstances:
As part of initiation of a program to test filters before reuse in
accordance with the NRC's requirement in Appendix A to 10 CFR 20, footnote
d-2(b), in July 1983, Three Mile Island (TMI) personnel tested new, unused
MSA Company's Ultra and PAPR filters. After testing at 85 liters per minute
flowrate and rejecting filters in excess of 0.025% leakage, TMI saw an
overall failure rate of less than 5% averaged over several cases (36 filters
per case). Filter failures tended to come in clusters, i.e., no failures for
several cases followed by a case with half failing. Most failures were
marginal or only slightly in excess of the NIOSH leakage requirement.
Subsequent confirmatory testing, performed by Los Alamos National Laboratory
(LANL) and others, of TMI's filters and testing by NIOSH of filters supplied
to them from NRC's regions confirmed that an excessive rate of filters were
failing. (See Attachment 1, Table 1 for results of NIOSH testing.) At
NIOSH's request in October 1983, MSA switched to more restrictive quality
control criteria on an interim basis (rejection at greater than 0.02%
leakage versus rejection at greater than 0.03% leakage and performing
quality control
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IN 84-60
August 6, 1984
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testing at the generally more restrictive airflow rate of 85 versus 32
liters per minute). A comparison study undertaken among NIOSH, MSA Company,
and TMI on 144 new unused filters that had undergone quality control testing
under the interim, more restrictive quality control criteria revealed no
failures. (See Attachment 1, Table 2 for results of comparison testing.) To
ensure adequate resolution of this problem and to prevent recurrence, MSA
Company has committed to the following actions to correct the excessive
filter failure rate problem:
1. All production and quality control testing of both types of filters
will be done at 85 liters per minute and accepted at not more than
0.02% leakage.
2. All filters with leakage readings in excess of 0.02% leakage will be
discarded.
3. All filters will be individually marked with week and year of
manufacture to facilitate the timely identification and resolution of
any future problems.
4. Tightened inspection procedures will be implemented and the need for
any new or additional tests or test equipment will be evaluated.
5. Manufacturing processes have been examined resulting in more stringent
process controls.
Guidance:
Quality Assurance (QA) inspection and testing conducted before the use of
new respiratory equipment helps ensure respirators will provide workers
adequate protection. In NUREG-0041, "Manual of Respiratory Protection
Against Airborne Radioactive Material," Section 10, "Quality Assurance,"
definitive guidance is provided for establishing a QA program for respirator
equipment. Obviously, the degree of QA effort will vary depending on the
type of respirator. Complex equipment such as the self-contained breathing
apparatus (SCBA) should receive priority QA effort, since SCBA's are used to
protect workers in areas immediately hazardous to life and health (IDLH).
While the immediate worker safety consequences of respirator malfunction are
much less severe for a negative pressure device, reasonable QA efforts can
be justified to help ensure adequate worker protection against airborne
radioactive materials. Even with the simplest design many things can go
wrong. For instance, if a hair or other obstruction is lodged between a
negative-pressure respirators exhalation valve and valve seat, leakage rates
as high as 10 percent have been observed. Likewise, filter leakage can in
the extreme case, degrade protection for negative pressure devices (allowed
a protection factor up to 50) and in the case where filter leakage is not
great for PAPR devices (allowed a protection factor of 1000).
As part of their QA program, LANL has tested a very large number of new,
unused filters over a period of many years for their in-house respirator
program and has observed a failure rate of about 2%; i.e., about 2% of the
filters stamped by the manufacturer as having a leakage rate of less than
0.03% were found to
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IN 84-60
August 6, 1984
Page 3 of 3
be leaking more than that. Because LANL data showed the majority of these
filters that failed had a leakage rate only marginally greater than 0.03%
and because the protection factors (see Attachment 2) authorized by 10 CFR
20 are believed to be conservative, the NRC staff has considered this
situation to be generally acceptable. (Note that especially for
negative-pressure types of respirators, face-to-facepiece leakage is usually
the limiting factor --the sealing area around the wearer's face is typically
the greatest source of leakage.)
Concentrations of airborne particulate radioactive materials at nuclear
power plants and other licensed facilities are generally sufficiently low
and worker exposure times typically sufficiently brief so that the
protection factors necessary to achieve compliance with the 10 CFR 20
quarterly radioactive material intake limit are generally well below the
protection factors allotted for filter respirators. Thus, the NRC staff has
no reason to believe measurable increases in exposures of workers to
airborne radioactive material resulted from the MSA filter problem.
NIOSH and the NRC staff believe that MSA Company's product improvement
commitments will suffice to correct the problem. NIOSH is relying on their
routine field audit program and information supplied to them from users in
the field to corroborate this belief (see Attachment 3). Licensees that have
remnants of orders purchased before the date that the manufacturer
instituted the more restrictive quality control rejection criteria (October
15, 1983) may want to do representative sampling of cases of new, unused
filters as recommended in NUREG-0041 (page 10-3).
Recipients should review the information discussed in this notice for
possible applicability to the respiratory protection program at their
facility. No written response to this information notice is required. If you
desire additional information regarding this matter, contact the Regional
Administrator of the appropriate NRC regional office or this office.
Edward L. Jordan Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: L. Hendricks, IE
(301) 492-9728
J. Wigginton, IE
(301) 492-4967
Attachments:
1. Results of Filter Testing
2. Relating Protection Factors to Removal Efficiencies
3. NIOSH Guidelines for Reporting Respiratory Field Problem
4. List of Recently Issued IE Information IE Information Notices
Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021