Document: NUREG-0800
Document ID: 90555c0d-360d-4a21-9859-bfb3cf6f2aea
Document Type: srp
Title: SEISMIC INSTRUMENTATION
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1332/ML13324A570.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.7.4
CFR Part: 
CFR Title: 

Content:
d on other 3.7.4-4 Revision 3 - July 2014 Seismic Category I structure foundations located at elevations different from the containment elevation. Refer to the latest version of RG 1.12 for a complete list of locations. Triggering of the free-field or any foundation-level accelerograph should be annunciated in the control room. In addition, applicants should provide a rationale for the placement of instrumentation that is consistent with maintaining occupational radiation exposures ALARA for the location. Consistent with the guidance provided within RG 8.8 Positions C.2, for meeting the requirements of 10 CFR Part 20, appropriate station layout and design features should be provided to reduce the potential doses to personnel who must operate, service, or inspect station instrumentation and controls. Instrumentation must satisfy functional requirements, but the exposure of personnel can be reduced if the instruments are designed, selected, specified, and located with consideration for long service life, ease and low frequency of maintenance and calibration. The free-field instrumentation should be located on the ground surface at the location sufficiently distant from the structures to be essentially unaffected by the vibration of the structures. The subsurface structure under the free-field sensor should be similar to that under the nuclear island. In-structure instrumentation located at key locations in Seismic Category I structures provide data for direct comparison with the seismic design parameters. With regard to operability and installation, applicants should demonstrate that the seismic instrumentation will be operable during all modes of plant operation, including periods of plant shutdown. In addition, the applicant’s maintenance and repair procedures should provide for keeping the maximum number of instruments (i.e., the greatest number of instruments possible given the constraints of the system) in service during plant operation and shutdown.