Lessons Learned Database



Title:

Vital Safety System Filter Degradation

Identifier:

2004-RL-HNF-0041

Date:

2004-10-13

Lesson Learned Statement:

Contractors must institutionalize site-wide processes/programs that guide facility management in determining operability of safety class equipment such as HEPA filters.

Potential age-related degradation of two ventilation filters at PFP resulted in an Unreviewed Safety Question (USQ).

Discussion:

On April 22, 2004 the Plutonium Finishing Plant (PFP) Design Authority (DA) for ventilation systems determined that Safety Class filters F-A12 and F-D12 were operable up to only 6" Water Gauge (WG), due to their age. Those filters may be exposed to greater than 6" WG during some accident scenarios. The filters were isolated by closing their dampers pending replacement.

On July 7, 2004 the Potential Inadequacy Safety Analysis (PISA) concerning those filter boxes not meeting operability requirements was evaluated to be an Unreviewed Safety Question. By then the filters had been replaced.

Analysis:

In the facility safety basis filters F-A12 and F-D12 are credited with mitigating consequences of several identified accident conditions. A HEPA Filter Degradation evaluation in April 2004, based on recent studies and criteria in DOE-HDBK-1169-2003, Nuclear Air Cleaning Handbook, indicated that filters F-A12 & F-D12 (manufactured in 1966) would not withstand an 8" differential pressure assumed in the Facility Hazard Analysis and Facility Safety Analysis Report (FSAR) accident analysis. The previous analyses four years earlier had determined that the filters were adequate.

Recommended Actions:

- Establish a requirement in a recall database that assures an annual degradation assessment is performed on all credited PFP safety-class and safety-significant HEPA filters.

- Issue a site wide evaluation procedure for assessing filter degradation in safety-class and safety-significant HEPA Filter systems.

Originator:

Fluor Hanford, Inc. Submitted by Bill Richards (509) 373-2327

Validator:

John Bickford

Contact:

Project Hanford Lessons Learned Coordinator; (509) 373-7664

Name Of Authorized Derivative Classifier:

Not required

Name Of Reviewing Official:

John Bickford

Priority Descriptor:

Blue / Information

Keywords:

HEPA filter operability

References:

Occurrence Report RL--PHMC-PFP-2004-0008
DOE-HDBK-1169-2003, Nuclear Air Cleaning Handbook (Handbook)
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DOE Function / Work Categories:

Authorization Basis
Maintenance - HVAC
Maintenance - Safety Systems

ISM Category:

Feedback and Improvement

Hazard:

Radiological Release

End of Lesson!

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