TY - JOUR
T1 - Calculating conditional core damage probabilities for nuclear power plant operations
AU - Smith, Curtis L.
N1 - Funding Information:
This work was partially supported by the US Nuclear Regulatory Commission under DOE Idaho Field Office Contract DE-AC07-94-ID13223. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for any third party's use, or the results of such use, of any information, apparatus, product or process disclosed in this report, or represents that its use by such third party would not infringe privately owned rights. The views expressed in this report are not necessarily those of the U.S. Nuclear Regulatory Commission. The author would like to thank several colleagues in the Nuclear Risk Management Technologies branch of the Idaho National Engineering and Environmental Laboratory for their assistance leading to the development of this paper. Specifically, I would like to thank Dana Kelly, John Schroeder, Mike Calley, Tami Thatcher, and Jim Knudsen for the investigative and inquisitive help that ultimately made its way into this paper. Also, I would like to thank Jacquie Janibagian, also of the Idaho National Engineering and Environmental Laboratory, for her editorial assistance.
PY - 1998/3
Y1 - 1998/3
N2 - A part of managing nuclear power plant operations is the control of plant risk over time as components are taken out of service or plant upsets are caused by initiating events. Unfortunately, measuring risk over time proves to be challenging, even with modern probabilistic risk analyses (PRAs) and PRA tools. In general, the process of measuring the operational risk would satisfy three desires: (1) the measurement would provide the risk magnitude for a particular event or over a period of time; (2) the risk results could be summed for a period of time to obtain a cumulative risk profile; and (3) the measurement process would be tractable while still using the current modeling techniques and tools. This paper demonstrates the calculation of the conditional core damage probability (CCDP) for the two cases of component outages and initiating events. In addition, two potential complications were identified that must be addressed when performing a CCDP calculation. The first complication, determining the appropriate nonrecovery probabilities to be applied to an inoperable component or initiating event, addresses the possibility of the plant operators preventing damage to the plant from their actions. The second complication, adjusting common-cause probabilities specific to the plant configuration, accounts for the fact that the PRA common-cause probabilities built into the model are applicable only during nominal conditions. The examples presented in the paper illustrate the potential under-estimation in CCDP when modifications to common-cause probabilities are ignored. These underestimation errors ranged from a factor of two to over a factor of six underestimation in CCDP.
AB - A part of managing nuclear power plant operations is the control of plant risk over time as components are taken out of service or plant upsets are caused by initiating events. Unfortunately, measuring risk over time proves to be challenging, even with modern probabilistic risk analyses (PRAs) and PRA tools. In general, the process of measuring the operational risk would satisfy three desires: (1) the measurement would provide the risk magnitude for a particular event or over a period of time; (2) the risk results could be summed for a period of time to obtain a cumulative risk profile; and (3) the measurement process would be tractable while still using the current modeling techniques and tools. This paper demonstrates the calculation of the conditional core damage probability (CCDP) for the two cases of component outages and initiating events. In addition, two potential complications were identified that must be addressed when performing a CCDP calculation. The first complication, determining the appropriate nonrecovery probabilities to be applied to an inoperable component or initiating event, addresses the possibility of the plant operators preventing damage to the plant from their actions. The second complication, adjusting common-cause probabilities specific to the plant configuration, accounts for the fact that the PRA common-cause probabilities built into the model are applicable only during nominal conditions. The examples presented in the paper illustrate the potential under-estimation in CCDP when modifications to common-cause probabilities are ignored. These underestimation errors ranged from a factor of two to over a factor of six underestimation in CCDP.
UR - https://www.scopus.com/pages/publications/0032010571
U2 - 10.1016/S0951-8320(97)00152-X
DO - 10.1016/S0951-8320(97)00152-X
M3 - Article
AN - SCOPUS:0032010571
SN - 0951-8320
VL - 59
SP - 299
EP - 307
JO - Reliability Engineering and System Safety
JF - Reliability Engineering and System Safety
IS - 3
ER -