CONFINEMENT OF RADIOACTIVE MATERIALS Defense Nuclear Facilities Safety Board Technical Report

["Marco Caceci" <chemitech@chemitech.com>]

http://www.deprep.org/2004/fb04d07b.htm



Defense Nuclear Facilities Safety Board Technical Report



EXECUTIVE SUMMARY



            The design of defense nuclear facilities includes systems whose

reliable operation is vital to the protection of the public, workers, and

the environment.  Confinement ventilation systems are among the most

important of such systems for protecting the public, and are generally

relied upon as the final safety-class barrier to the release of hazardous

materials with potentially serious public consequences.  The Defense Nuclear

Facilities Safety Board (Board) has advised the Department of Energy (DOE)

in various ways during the past decade regarding the need to increase

attention to the design and operational reliability of these important

systems.



            The Board, however, has recently observed a fundamental change

in the approach to protection of the public at certain defense nuclear

facilities.  This change has resulted in downgrading of the functional

safety classification of confinement ventilation systems.  Specifically, DOE

contractors operating or designing defense nuclear facilities have, through

a strong reliance on analytical estimates of passive leakage, prepared

safety bases that have resulted in downgrading and sometimes elimination of

the safety-class function of confinement ventilation systems.  This approach

can potentially result in the unfiltered release of air containing

radioactive materials during an accident.



            This report describes this misuse of DOE requirements, which

provides only minimum levels of required protection to the public.  The

report also compares this approach with the traditional approach of using a

safety-class confinement ventilation system; hence, minimizing more

effectively any off-site radiological impact.



            In addition, this report demonstrates that analytical tools used

to predict passive leakage do not account for many of the uncertainties

involved (e.g., the dynamics of the event, diurnal effects, wind, emergency

evacuation or egress).  Passive leakage analyses often do not consider all

of the issues that must be addressed should an accident occur.  These

include monitoring of releases, limiting contamination, and supporting

accident recovery.  These uncertainties and additional considerations

further justify a preference for a safety-class confinement ventilation

system as the primary means of protecting the public against the potential

release of radioactive material.



            In light of these observations, DOE needs to provide additional

guidance and explicitly state its policy regarding adequate protection of

the public and workers by mandating a safety- related active confinement

ventilation system for those defense nuclear facilities that pose the

potential for significant radiological consequences.



-------------



Marco Caceci





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