Fire Scenarios

DOE-HDBK-1129-99

conducted to make sure the system or component was fabricated and installed as specified in the

design documents. Documentation must be maintained current throughout the life of the item.

Evaluation of existing systems or components must be conducted based on the "Actual" condition

of the item. This may be different than the design or "As-Built" condition due to field modifications

or deterioration of the item during its service. An examination of the item, its installation, and

current condition should be made during a walkdown by seismic engineers as defined in the SEP.

Existing systems and components may also be evaluated by use of experience data. This is an

alternative approach that can be used if the systems or components are installed in an acceptable

manner and meet the rules specified in the SEP to ensure that the item is similar to items in the

experience database. DOE has developed resources for the evaluation of existing systems and

components, has conducted training on their application, and has been implementing the

development of seismic evaluation guidelines for systems and components at DOE facilities.

5.8 Fire Scenarios

There have been recent investigations that point to the conclusion that fire scenarios are the

dominant risk at most tritium facilities. These fire scenarios are not restricted to seismic-induced

fires, but include fires from all sources. These recent analyses show that the slower burning fires

are limiting, and that in almost all cases, these fires result in oxidation rates that are high (in

excess of 90%). Additionally, compliance with National Fire Protection Association (NFPA)

requirements, while limiting the potential for fire spread, does not ensure that a full-facility fire

scenario need not be analyzed. Reference [26] describes the latest findings in this area.

It is possible that fires of sufficient magnitude and frequency exist at some tritium facilities so as to

warrant safety system classifications of both the fire suppression and fire detection systems. It has

long been the position of EH-3 that tritium fire suppression and detection systems should be

classified as safety systems (at a minimum as safety-significant, and in some cases as safety-

class (e.g., where other safety-class equipment operation is contingent upon fire system operation

or where fire scenarios result in unacceptable public dose)), unless documented analyses such as

the FHA or the SAR justify non-classification. This importance that EH-3 places on fire protection

at tritium facilities was highlighted as early as September 1991 during a review of the then-under-

construction RTF. The exemption request from some requirements of DOE Orders 5480.7 and

6430.1A for RTF were not approved by EH/NS until physical modifications were made to the tritium

facility. [27]. The definition of tritium that was Material at Risk in selected fire (and seismic)

scenarios was also developed prior to startup at RTF, which eventually led to decisions on

upgraded selected storage containers and inventory limits. [28]

5.9 Instrumentation

This section provides information on several instruments used to detect and monitor tritium. The

references are provided for information only. DOE does not certify that a particular product is

superior to any other product from another vendor. References in this Handbook do not imply

endorsement by DOE.

5.9.1 Tritium Monitoring Systems

Several different types of instruments may be used to detect and measure tritium in the operation

of a facility. Examples and a discussion of such instrumentation follow: