United States Nuclear Regulatory Commission - Protecting People and the Environment

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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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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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, November 12, 2013