Document: NRC Regulatory Guide
Document ID: 99fe445b-c440-4921-ba8f-841c8f236046
Document Type: regulatory_guide
Title: Nuclear Power Plant Instrumentation for Earthquakes + HISTORY - HISTORY 09/2016 – DG-1332 , Proposed Revision 3 04/2015 – Periodic Review on Revision 2 – Revise 02/1995 – DG-1033, Third Proposed Revision 2 11/1992 – DG-1016, Second Proposed Revision 2 07/1981 – Draft MS 140-5 , First Proposed Revision 2 (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1610/ML16104A220.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.12
CFR Part: 
CFR Title: 

Content:
G 1.12 dates to 1997 and significant technological advances in seismic instrumentation have since been made since then. In addition, lessons learned from the recent earthquakes that impacted the North Anna Power and Fukushima-Dai-ichi Nuclear Power Plants indicate a need to update seismic instrumentation guidance relative to instrument characteristics, locations, installation, and maintenance. Background When an earthquake occurs, it is important to take prompt action to assess the effects of the earthquake at the nuclear power plant. This assessment includes both an evaluation of the seismic instrumentation data and a plant walkdown. Acceleration sensors and solid-state digital time-history recorders installed at appropriate locations will provide time-history acceleration data on the seismic response in the free-field, containment structure, and other Seismic Category I structures. The acceleration sensors need to be located so that the response may be compared and evaluated with the design basis, which are typically ground motion or in-structure response spectra. The sensors are intended to be installed such that occupational radiation exposures associated with their location, installation, and maintenance are maintained as low as reasonably achievable (ALARA). Thorough documentation of instrument, components, and as-installed supporting systems is needed to enable operation, maintenance, and testing. These functions enable confident use of the data. Instrumentation is provided in the free-field, at the foundation level, and at elevations in Seismic Category I structures. Free-field instrumentation data is used to compare measured response to the engineering evaluations used to determine design input motion to the structures and to determine whether the OBE has been exceeded. RG 1.166 provides useful information for determination of OBE exceedence. The instruments located at the foundation level and at elevation in the structures measure responses that are the