ABSTRACT:

The geotechnical investigations carried out at two different NPP sites are part of the detailed site investigation program. It includes studies such as, assess- ment of rock mass conditions encountered at the two NPP sites and determination of geotechnical parameters by field investigations, determination of physical and mechanical properties of the basic rock types by laboratory tests, evaluation of the stability of foundations and pit slopes under design loading conditions by engineering analyses. Based on these studies the most favorable layouts for various NPP units are suggested.

1 QUALITY ASSURANCE PROGRAM

Before the initiation of the geotechnical investigations, a constituent QA Program was developed as requested both by International Atomic Energy Agency (IAEA) and Nuclear Power Plant Division of the Turkish Electricity Authorities (TEK-NSD). The purpose of the QA program was to establish a basis for control and verification of all activities in accordance with defined and documented procedures and work instructions.

The QA program for the specified activities presented in "METU-ROCK Manual", consists of two parts. The first part (QAPD-SI)includes the following program documents:

  • QA program description,

  • program procedures, and

  • quality Plans.

The second part of the manual (QAP-WPI-S2) includes documents on work procedures and instructions for (i) field investigations, (ii) laboratory testing, and (iii) engineering analyses.

2 FIELD INVESTIGATION

The purpose of the field investigations carried out at both NPP Sites, was to Provide sufficient geotechnical information on various engineering problems studied so that there was a reasonable assurance that subsurface conditions are sufficiently well understood to permit adequate engi- neering solutions of the actual or potenti- al problems at the site. During the investigations, rock mass conditions and geotechnical parameters were evaluated to permit rational decisions to be made with respect to site suitability and engineering solutions to be suggested for unusual and difficult site conditions.

In general, the following activities were carried out during the field investigation program:

  1. Establishment of a borehole drilling program

  2. Assessment of rock mass condition

  3. Determination of geotechnical parameters

2.1 Borehole drilling program

The geotechnical investigations were carried out at two different sites located on Mediterranean cost (Site-A) and Black Sea Cost (Site-B). The study areas and location of the boreholes utilized during the investigations are presented in Figures 1 and 2 respectively for Site A and Site B.

The drilling program for Site-A has been carried out in three stages. In the first stage a total of 21 boreholes were drilled sperated at 120m intervals. In this way the site area is thoroughly covered in order to have a preliminary assessment of the subsurface geological conditions.

Based on the results of the first drilli.ncr compaign the second stage of core drilling program was initiated. In this stage borehole spacing is reduced to 60 m.

(Figure in full paper)

boreholes were mostly concentrated within the Db-8 member of "BF" and "AF" formations. The boreholes assigned to "BF" formation have locally penetrated sore subsurface cavities, therefore, earlier planned plant layouts is shifted slightly to the SW.

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