Life Extension Techniques

DOESTD107393

There is a potential overlap between the feasibility studies conducted in this detailed MCA phase and

the activities of the ongoing phase of the MCA program. If DOE has specified a desired lifetime for the

facility that is significantly longer than the remaining lifetime, it is necessary to develop life extension

techniques. When the need for life extension techniques is clear, they should be developed during this

phase, at least to the extent that there is a basis for recommendation for life extension techniques for

the ongoing MCA phase, and the costs of development and implementation of those techniques should

be estimated and included In the feasibility study (to the extent that the costs of those techniques can

be estimated).

Similarly, the feasibility study should include recommendations for periodic MCA monitoring of

equipment, based on the measurements of the baseline material conditions used in the aging

degradation evaluations, and for trending the results to predict the end of life for life-limiting

components.

4.3 LIFE EXTENSION TECHNIQUES

Life extension techniques make it possible to operate a component beyond Its normal lifetime. Life

extension techniques include actions that reduce stresses, such as operational changes and

hardware/facility modifications, and those that reduce the effects of stresses. Generally, life extension

techniques are applied only to components that have been determined to be life-limiting for the facility.

The development and application of such techniques have associated costs, as estimated during the

feasibility study. These costs should not be incurred unless DOE has specifically directed such

expenditures or has specified a desired lifetime that is greater than the remaining lifetime of the facility.

Environmental stressors, such as temperature and radiation, which are known to induce aging

degradation, particularly in non-metallic materials, can be characterized and their impact reduced to

extend component life. Collection and evaluation of environmental data can provide the basis for

adjustments to environmental conditions, such as by additional thermal insulation, venting of electrical

enclosures, HVAC upgrades, the addition of radiation shielding, and periodic decontamination of piping

near the equipment.

Adjustments in operational practices can extend component life. Such adjustments may include

reducing the period of operation, decreasing the number and rate of startups/shutdowns, and

optimizing or improving testing practices that contribute to equipment degradation.

Upgrading the design can also extend the lifetime. Equipment manufacturers and the commercial

nuclear industry develop life-extending design enhancements based on operating experience and the

availability of new technology/materials. These include changing to materials more resistant to aging

stressors or reconfiguring for improved reliability. For example, during research conducted on electrical

inverters, an evaluation of several design configurations demonstrated that the use of an automatic

transfer switch improves the reliability of the power supplied to controls and equipment. Other

recommended design improvements include the use of higher ratings for voltage- and temperature--

sensitive components in the inverter circuitry, and the addition of forced-air cooling to reduce

overheating problems.

4.4 ONGOING MCA PHASE

With the completion of the detailed or main MCA phase, the development of the MCA program is

essentially complete. The ongoing MCA phase involves simply adapting previously developed MCA

actions for incorporation into the ongoing CM program. For example, a one-time measurement method

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