**4.3. Development of emergency operational procedures**

100 Nuclear Power – Practical Aspects

Hz."

together to arrive at the CAV.

and plant shutdown is required.

**4.2. Seismic instrumentation** 

main components.

2003b).

reactor protection system.

The seismic instrumentation has two important roles:


1. The corresponding design response spectral acceleration (OBE spectrum if used in the design, otherwise 1/3 of the safe shutdown earthquake ground motion (SSE) spectrum)

2. The corresponding design response spectral velocity (OBE spectrum if used in the design, otherwise 1/3 of the SSE spectrum) or a spectral velocity of 6 inches per second (15.24 centimeters per second), whichever is greater, for frequencies between 1 and 2

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where a(t) is a component of the ground acceleration, T is the duration of the strong motion.

There are certain rules for the numerical calculation of the CAV: (1) the absolute acceleration (g units) time-history is divided into 1-second intervals, (2) each 1-second interval that has at least 1 exceedance of 0.025g is integrated over time, (3) all the integrated values are summed

If the response spectrum check and the CAV check were exceeded, the OBE was exceeded

The CAV check is exceeded if any CAV calculation is greater than 0.16 g-seconds.


The instrumentation providing response records for the evaluation post-event condition of the plant should be installed at most important/significant location of the structures and

The instrumentation for the judgement on the OBE exceedance has to be designed and fitted to the concept of limitation of the operation in case of earthquake. The instrumentation and voting logic for automatic scram should have the same structure, redundancy etc. as the

For example the Soviet designed SIAZ (System of Industrial Antisesmic Protection) system initiating automatic reactor scram consists of nine tri-axial accelerometers in three independent systems with independent electric power supply and two sets of them. Contrary to this the tri-axial accelerometers for evaluation of OBE exceedance via CAV and

Regarding design and installation of seismic instrumentation see (NRC, 1997c) and (IAEA,

response spectrum criteria should be installed at protected free-field locations.

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or 0.2g, whichever is greater, for frequencies between 2 to 10 Hz, or

The CAV is defined for each component of the free-field ground motion as

Activities that have to be executed during earthquake should be defined and adequate emergency operational procedures for accident prevention should be developed for the case of earthquake. The documents (NRC, 1997a, 1997b and 2000; EPRI, 1988; 1989, ANS 2002) and the (IAEA, 2011) provide guidelines for the development of the procedure.

The development of earthquake related severe accident management guidelines can be performed on the basis of severe accident oriented studies (Section 3.4) and IAEA documents (IAEA, 2009b).
