Evaluation of Existing Facilities

DOE-STD-1020-2002

2.4.2 Evaluation of Existing Facilities

It is anticipated that these criteria would also be applied to evaluations of existing

facilities. General guidelines for the seismic evaluation of existing facilities are presented in

National Institute of Standards and Technology documents (Refs. 2-16 and 2-17). In addition,

guidelines for upgrading and strengthening equipment are presented in Ref. 2-20. Also,

guidance for evaluation of existing equipment by experience data is provided in References 2-5

and 2-13. These documents should be referred to for the overall procedure of evaluating seismic

adequacy of existing facilities, as well as for specific guidelines on upgrading and retrofitting.

Once the as-is condition of a facility has been verified and deficiencies or weak links

have been identified, detailed seismic evaluation and/or upgrading of the facility as necessary

can be undertaken. Obvious deficiencies that can be readily improved should be remedied as

soon as possible. Seismic evaluation for existing facilities would be similar to evaluations

performed for new designs except that a single as-is configuration is evaluated instead of several

configurations in an iterative manner (as is often required in the design process). Evaluations

should be conducted in order of priority. Highest priority should be given to those areas

identified as weak links by the preliminary investigation and to areas that are most important to

personnel safety and operations with hazardous materials. Input from safety personnel and/or

accident analyses should be used as an aid in determining safety priorities.

The evaluation of existing facilities for natural phenomena hazards can result in a number

of options based on the evaluation results. If the existing facility can be shown to meet the

design and evaluation criteria presented in Sections 2.3.1 or 2.3.2 and good seismic design

practice had been employed, then the facility would be judged to be adequate for potential

seismic hazards to which it might be subjected. If the facility does not meet the seismic

evaluation criteria of this chapter, a back-fit analysis should be conducted. Several alternatives

can be considered:

If an existing SSC is close to meeting the criteria, a slight increase in the

annual risk to natural phenomena hazards can be allowed within the

tolerance of meeting the target performance goals (See Section 1.3). Note

that reduced criteria for seismic evaluation of existing SSCs is supported

in Reference 2-16. As a result, some relief in the criteria can be allowed

by performing the evaluation using hazard exceedance probability of twice

the value recommended in Table 2-1 for the Performance Category of the

SSC being considered.

The SSC may be strengthened such that its seismic resistance capacity is

sufficiently increased to meet these seismic criteria. When upgrading is

required it should be designed for the current design criteria.

The usage of the facility may be changed such that it falls within a less

hazardous Performance Category and consequently less stringent seismic

requirements.

2-21