Risk Metrics - Revision history

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2025-01-24T18:23:33Z

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Admin: /* Advanced Reactor Risk Metrics */

2025-01-23T22:56:01Z

Advanced Reactor Risk Metrics

← Older revision		Revision as of 22:56, 23 January 2025
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	==Advanced Reactor Risk Metrics==		==Advanced Reactor Risk Metrics==
	Decades of operation of water reactor technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies not cooled by water, the water reactor metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References\|[7]]] has been developed to help fill some of the gaps identified between water reactor risk metrics and advanced reactor risk metrics.		Decades of operation of water reactor technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies not cooled by water, the water reactor metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References\|[7]]] has been developed to help fill some of the gaps identified between water reactor risk metrics and advanced reactor risk metrics.
	In November 2024, EPRI released a new report EPRI [https://www.epri.com/research/programs/061177/results/3002029252 3002029252] [[References\|[60]]] that addresses ~~the research actions in determining the proper~~ risk metrics for ~~advanced reactors. The report identifies Quantitative Health Objective (QHOs) as the basis for the development of all risk metrics including~~ advanced reactors.		In November 2024, EPRI released a new report EPRI [https://www.epri.com/research/programs/061177/results/3002029252 3002029252] [[References\|[60]]] that addresses a process to determine risk metrics for advanced reactors.
	The primary questions that EPRI 3002029252 aims to answer are the following:		The primary questions that EPRI 3002029252 aims to answer are the following:
	*What are the strengths and weaknesses of existing risk metrics for application to advanced reactors?		*What are the strengths and weaknesses of existing risk metrics for application to advanced reactors?
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	*For advanced reactor designs that are not conducive to the use of existing risk metrics, what metrics can be developed and used?		*For advanced reactor designs that are not conducive to the use of existing risk metrics, what metrics can be developed and used?

	The Key Findings in EPRI 3002029252 recommend a primary technology-neutral risk metric, offsite dose emergency action frequency (ODEAF), defined as a 50 mSv (5 rem) projected mean dose at the facility boundary for a period of four days following the start of a release. This approach is consistent with existing regulatory objectives and guidance (for example, NEI 18-04 [[References\|[8]]], the United States Quantitative Health Objectives, and various International Atomic Energy Agency guidance documents) as well as existing regulatory targets from several national regulatory authorities.		The Key Findings in EPRI 3002029252 recommend a primary technology-neutral risk metric, offsite dose emergency action frequency (ODEAF), defined as a 50 mSv (5 rem) projected mean dose at the facility boundary for a period of four days following the start of a release. This approach is consistent with existing regulatory objectives and guidance (for example, NEI 18-04 [[References\|[8]]], the United States Quantitative Health Objectives, and various International Atomic Energy Agency guidance documents) as well as existing regulatory targets from several national regulatory authorities. EPRI 3002029252 also provides supporting guidance on the creation of preventive risk metrics and demonstration of consistency with high-level safety objectives.

	~~Key~~ topics related to risk metrics for advanced reactor technologies that ~~are to~~ be further ~~investigated~~ include:		Additional topics related to risk metrics for advanced reactor technologies that may be worthy of further investigation by the industry include:
	*Importance measures to correspond to different risk metrics for ARs, including changes to use absolute measures rather than relative measures (as supported by the Non-LWR PRA Standard [6])		*Importance measures to correspond to different risk metrics for ARs, including changes to use absolute measures rather than relative measures (as supported by the Non-LWR PRA Standard [6])
	*Guidance for the utilization of different risk metrics for ARs related to the need to support requirements to identify significant contributors for the application of requirements in the PRA standards		*Guidance for the utilization of different risk metrics for ARs related to the need to support requirements to identify significant contributors for the application of requirements in the PRA standards

Admin: /* Purpose */

2025-01-17T21:15:59Z

Purpose

← Older revision		Revision as of 21:15, 17 January 2025
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	==Purpose==		==Purpose==
	Develop quantitative and qualitative metrics that can be used in risk modeling for advanced reactors to make risk-informed decisions on plant design in a similar fashion to how core damage frequency (CDF) and large early release frequency (LERF) are currently used for ~~LWRs~~.		Develop quantitative and qualitative metrics that can be used in risk modeling for advanced reactors to make risk-informed decisions on plant design in a similar fashion to how core damage frequency (CDF) and large early release frequency (LERF) are currently used for water reactors.

	==Scope==		==Scope==

Admin: /* Advanced Reactor Risk Metrics */

2025-01-17T21:14:04Z

Advanced Reactor Risk Metrics

← Older revision		Revision as of 21:14, 17 January 2025
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	==Advanced Reactor Risk Metrics==		==Advanced Reactor Risk Metrics==
	Decades of operation of ~~LWR~~ technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies, the ~~LWR~~ metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References\|[7]]] has been developed to help fill some of the gaps identified between ~~LWR~~ risk metrics and advanced reactor risk metrics.		Decades of operation of water reactor technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies not cooled by water, the water reactor metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References\|[7]]] has been developed to help fill some of the gaps identified between water reactor risk metrics and advanced reactor risk metrics.
	In November 2024, EPRI released a new report EPRI [https://www.epri.com/research/programs/061177/results/3002029252 3002029252] [[References\|[60]]] that addresses the research actions in determining the proper risk metrics for advanced reactors. The report identifies Quantitative Health Objective (QHOs) as the basis for the development of all risk metrics including advanced reactors.		In November 2024, EPRI released a new report EPRI [https://www.epri.com/research/programs/061177/results/3002029252 3002029252] [[References\|[60]]] that addresses the research actions in determining the proper risk metrics for advanced reactors. The report identifies Quantitative Health Objective (QHOs) as the basis for the development of all risk metrics including advanced reactors.
	The primary questions that EPRI 3002029252 aims to answer are the following:		The primary questions that EPRI 3002029252 aims to answer are the following:
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	*Application of risk metrics for ARs throughout the life cycle as the plant and associated PRA evolve during design, construction, and operation		*Application of risk metrics for ARs throughout the life cycle as the plant and associated PRA evolve during design, construction, and operation
	*Application of risk metrics to non-core sources of radioactivity (for example, spent fuel)		*Application of risk metrics to non-core sources of radioactivity (for example, spent fuel)
	*Applicability of risk metrics to research and test reactors, which do not traditionally utilize PRA risk metrics like ~~LWRs~~		*Applicability of risk metrics to research and test reactors, which do not traditionally utilize PRA risk metrics like water reactors

Admin: /* Advanced Reactor Risk Metrics */

2025-01-17T21:05:39Z

Advanced Reactor Risk Metrics

← Older revision		Revision as of 21:05, 17 January 2025
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	==Advanced Reactor Risk Metrics==		==Advanced Reactor Risk Metrics==
	Decades of operation of LWR technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies, the LWR metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References\|[7]]] has been developed to help fill some of the gaps identified between LWR risk metrics and advanced reactor risk metrics		Decades of operation of LWR technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies, the LWR metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References\|[7]]] has been developed to help fill some of the gaps identified between LWR risk metrics and advanced reactor risk metrics.
	~~As of~~ 2024, EPRI ~~has~~ released a new report EPRI [https://www.epri.com/research/programs/061177/results/3002029252 3002029252] [[References\|[60]]] that addresses the research actions in determining the proper risk metrics for advanced reactors. The report identifies Quantitative Health Objective (QHOs) as the basis for the development of all risk metrics including advanced reactors.		In November 2024, EPRI released a new report EPRI [https://www.epri.com/research/programs/061177/results/3002029252 3002029252] [[References\|[60]]] that addresses the research actions in determining the proper risk metrics for advanced reactors. The report identifies Quantitative Health Objective (QHOs) as the basis for the development of all risk metrics including advanced reactors.
	The primary questions that EPRI 3002029252 aims to answer are the following:		The primary questions that EPRI 3002029252 aims to answer are the following:
	*What are the strengths and weaknesses of existing risk metrics for application to advanced reactors?		*What are the strengths and weaknesses of existing risk metrics for application to advanced reactors?

Admin: /* Advanced Reactor Risk Metrics */

2025-01-17T21:03:50Z

Advanced Reactor Risk Metrics

← Older revision		Revision as of 21:03, 17 January 2025
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	The Key Findings in EPRI 3002029252 recommend a primary technology-neutral risk metric, offsite dose emergency action frequency (ODEAF), defined as a 50 mSv (5 rem) projected mean dose at the facility boundary for a period of four days following the start of a release. This approach is consistent with existing regulatory objectives and guidance (for example, NEI 18-04 [[References\|[8]]], the United States Quantitative Health Objectives, and various International Atomic Energy Agency guidance documents) as well as existing regulatory targets from several national regulatory authorities.		The Key Findings in EPRI 3002029252 recommend a primary technology-neutral risk metric, offsite dose emergency action frequency (ODEAF), defined as a 50 mSv (5 rem) projected mean dose at the facility boundary for a period of four days following the start of a release. This approach is consistent with existing regulatory objectives and guidance (for example, NEI 18-04 [[References\|[8]]], the United States Quantitative Health Objectives, and various International Atomic Energy Agency guidance documents) as well as existing regulatory targets from several national regulatory authorities.

	~~Current Research Roadmap (EPRI [https://www.epri.com/research/products/000000003002026495 3002026495]) Actions Supported include:~~
	*Developing a Technical Input to Siting Criteria: In the envisioned advanced reactor licensing framework (as described in [https://www.nrc.gov/docs/ML1924/ML19241A472.pdf NEI 18-04] [[References\|[8]]]), assessment of plant risk (via characterization by F-C curves) provides a primary set of criteria in the licensing process. This R&D task will develop applicable risk metrics that can provide technical basis for site-specific licensing decisions.
	*Demonstrating a Risk-Informed and Performance Based Approach: Because the capability to effectively assess and monitor risk is a fundamental element for both plant owner / operator responsibilities and regulatory review / oversight in a risk-informed performance-based framework, this R&D activity can generally support demonstrating this risk-informed and performance-based framework.

	Key topics related to risk metrics for advanced reactor technologies that are to be further investigated include:		Key topics related to risk metrics for advanced reactor technologies that are to be further investigated include:

Admin: /* Advanced Reactor Risk Metrics */

2025-01-15T23:28:28Z

Advanced Reactor Risk Metrics

← Older revision		Revision as of 23:28, 15 January 2025
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	The Key Findings in EPRI 3002029252 recommend a primary technology-neutral risk metric, offsite dose emergency action frequency (ODEAF), defined as a 50 mSv (5 rem) projected mean dose at the facility boundary for a period of four days following the start of a release. This approach is consistent with existing regulatory objectives and guidance (for example, NEI 18-04 [[References\|[8]]], the United States Quantitative Health Objectives, and various International Atomic Energy Agency guidance documents) as well as existing regulatory targets from several national regulatory authorities.		The Key Findings in EPRI 3002029252 recommend a primary technology-neutral risk metric, offsite dose emergency action frequency (ODEAF), defined as a 50 mSv (5 rem) projected mean dose at the facility boundary for a period of four days following the start of a release. This approach is consistent with existing regulatory objectives and guidance (for example, NEI 18-04 [[References\|[8]]], the United States Quantitative Health Objectives, and various International Atomic Energy Agency guidance documents) as well as existing regulatory targets from several national regulatory authorities.


	~~<br>~~
	Current Research Roadmap (EPRI [https://www.epri.com/research/products/000000003002026495 3002026495]) Actions Supported include:		Current Research Roadmap (EPRI [https://www.epri.com/research/products/000000003002026495 3002026495]) Actions Supported include:
	*Developing a Technical Input to Siting Criteria: In the envisioned advanced reactor licensing framework (as described in [https://www.nrc.gov/docs/ML1924/ML19241A472.pdf NEI 18-04] [[References\|[8]]]), assessment of plant risk (via characterization by F-C curves) provides a primary set of criteria in the licensing process. This R&D task will develop applicable risk metrics that can provide technical basis for site-specific licensing decisions.		*Developing a Technical Input to Siting Criteria: In the envisioned advanced reactor licensing framework (as described in [https://www.nrc.gov/docs/ML1924/ML19241A472.pdf NEI 18-04] [[References\|[8]]]), assessment of plant risk (via characterization by F-C curves) provides a primary set of criteria in the licensing process. This R&D task will develop applicable risk metrics that can provide technical basis for site-specific licensing decisions.

Admin: /* Advanced Reactor Risk Metrics */

2025-01-15T23:28:07Z

Advanced Reactor Risk Metrics

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 ==Advanced Reactor Risk Metrics==
-Decades of operation of LWR technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies, the LWR metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A question that comes out of this conclusion is what changes to PRA methods and tools would be needed to support risk metrics that are more appropriate for advanced reactors (i.e., metrics other than CDF and LERF as specified in the ASME/ANS Non-LWR PRA Standard)? And are there metrics that can be implemented that would remain the same across designs similar to CDF and LERF? A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References|[7]]] has been developed to help answer these questions.
+Decades of operation of LWR technologies have developed a consensus on the risk metrics to be used for these technologies; in particular, the use of CDF and LERF as figures of merit. However, for non-LWR advanced reactor technologies, the LWR metrics may not be meaningful or useful for either regulatory or operational / management purposes because of the vastly different designs of advanced reactors. A trial Reg Guide [https://www.nrc.gov/docs/ML2123/ML21235A008.pdf 1.247] [[References|[7]]] has been developed to help fill some of the gaps identified between LWR risk metrics and advanced reactor risk metrics
 <br>
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 *Developing a Technical Input to Siting Criteria: In the envisioned advanced reactor licensing framework (as described in [https://www.nrc.gov/docs/ML1924/ML19241A472.pdf NEI 18-04] [[References|[8]]]), assessment of plant risk (via characterization by F-C curves) provides a primary set of criteria in the licensing process. This R&D task will develop applicable risk metrics that can provide technical basis for site-specific licensing decisions.
 *Demonstrating a Risk-Informed and Performance Based Approach: Because the capability to effectively assess and monitor risk is a fundamental element for both plant owner / operator responsibilities and regulatory review / oversight in a risk-informed performance-based framework, this R&D activity can generally support demonstrating this risk-informed and performance-based framework.

Admin: /* Scope */

2025-01-15T23:20:03Z

Scope

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	==Scope==		==Scope==
	Risk metrics should be expected to evolve over time as those used to investigate qualitative risk at an early stage of design for advanced reactors may be different from the ones used to investigate quantitative risk of a more mature design and licensing phase.		Risk metrics should be expected to evolve over time as those used to investigate qualitative risk at an early stage of design for advanced reactors may be different from the ones used to investigate quantitative risk of a more mature design and licensing phase. Different options for risk metrics are being explored that vary from a standardized form that can apply to various designs, like CDF and LERF, to site specific risk metrics that have different bases than CDF and LERF. Stakeholder feedback has suggested that whichever option is pursued should be technology neutral.

	==Advanced Reactor Risk Metrics==		==Advanced Reactor Risk Metrics==

Admin: /* Purpose */

2025-01-15T23:19:50Z

Purpose

← Older revision		Revision as of 23:19, 15 January 2025
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	==Purpose==		==Purpose==
	~~Identify~~ quantitative and qualitative metrics that can be used in risk modeling for advanced reactors to make risk-informed decisions on plant design in a similar fashion to how core damage frequency (CDF) and large early release frequency (LERF) are currently used for LWRs.		Develop quantitative and qualitative metrics that can be used in risk modeling for advanced reactors to make risk-informed decisions on plant design in a similar fashion to how core damage frequency (CDF) and large early release frequency (LERF) are currently used for LWRs.

	==Scope==		==Scope==