ML20209B719
| ML20209B719 | |
| Person / Time | |
|---|---|
| Issue date: | 07/09/1985 |
| From: | Goller K NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Taylor J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| Shared Package | |
| ML20209B402 | List: |
| References | |
| NUDOCS 8609080297 | |
| Download: ML20209B719 (2) | |
Text
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UNITED STATES g
NUCLEAR REGULATORY COMMISSION g
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- E WASHINGTON, D. C. 20555 a
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JULO S 1985 MEMORANDUM FOR:
James M. Taylor, Director Office of Inspection & Enforcement i
FROM:
Karl R. Goller, Director Division of Radiation Programs and Earth Sciences, RES
SUBJECT:
FAILURE OF SEISMIC STRONG GROUND MOTION ACCELER0 GRAPHS AT NUCLEAR POWER PLANTS Appendix A, " Seismic and Geologic Siting Criteria for Nuclear Power Plants," to 10 CFR Part 100, " Reactor Site Criteria," Paragraph VI(a)(3) provides the regulatory basis for the installation and operation of seismic strong ground motion accelerographs at nuclear power plants. This regulation states, in part, that, " Suitable instrumentation shall be provided so that the seismic response of nuclear power plant features important to safety can be determined promptly to permit comparison of such response with that used as the design basis. Such a comparison is needed to decide whether the plant can continue to be operated safely..."
Although this instrumentation is primarily intended to enable determining whether the ground motions of an earthquake felt by a nuclear power plant exceeded the design basis ground motions for that plant, an important secondary objective is to provide the NRC with ongoing information and bases for its current licensing requirements and practices. These are currently based primarily on theory and extrapolation from the behavior of non-nuclear facilities. The RES interests in this problem are incorporated in this secondary objective. We would like to obtain data from this instrumentation to validate seismic design codes, seismic margin assessments and to improve present models of strong ground motion propagation. Also, any data from this instrumentation could be a valuable addition to our regional earthquake monitoring networks in the eastern and central U.S. which are intended to provide information on the origins, probabilities and characteristics of earthquakes.in this region of the U.S.
Since Appendix A went into effect, a number of earthquakes have occurred which probably should have triggered the accelerographs in the NPP's, but they did The Lancaster, Pennsylvania, earthquake of 1984 is a good case in point.
not.
In that earthquake, the ground motion recorders at the Peach Bottom Plant did not trigger.
Inspection and testing of this instrumentation the day following the earthquake indicated that the system was inoperative. This occurred in i
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spite of the fact that the system had.just been inspected and tested 2 days before the earthquake.
It is our understanding that in many cases, routine inspection and testing of such instrumentation at NPP's is showing that it would not have performed properly if an earthquake had occurred. This situation is depriving us of valpable seismic data. Much more importantly, however, it means that there is a high probability that the intended information concerning the magnitude and nature of the ground motions to which a NPP is actually subjected during a seismic event will not be available. This could put the NRC in a difficult and awkward position concerning the restart of such a NPP.
These incidents of seismic instrumentation failure are likely related to the testing and maintenance procedures; or, more generally, the quality assurance program applied to them.
I recommend that this situation be reviewed to better establish the source of these failures so that appropriate measures may be undertaken to correct them.
In the interim, I suggest that you consider having resident inspectors increase their level of attention to the seismic instrumentation at NPP's.
Karl R. Goller, Director Division of Radiation Programs and Earth Sciences, RES cc:
J. Knight, NRR G. Arlotto, RES B. Grimes, IE E. Jordan, IE H. Thompson, NRR T. Speis, NRR
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