ML18242A447

August 21, 2018 Public Meeting Licensing Modernization Project Guidance - Slide Package (Enclosure 3)

ML18242A447
Person / Time
Issue date:	08/21/2018
From:	Reckley W D NRC/NRO/DSRA/ARPB
To:
Reckley W D, NRO/DSRA, 415-7490
Shared Package
ML18242A378	List: ML18242A396 ML18242A447
References
Download: ML18242A447 (28)

Text

Presentations for August 21, 2018 Public Meeting Licensing Modernizatoin Project Guidance Document In order of discussion, the meeting included the following topics and presentations 1)NRC Slides 2)Licensing Modernization Project Slides 3)Draft Glossary Advanced Reactor Guidance DocumentsAugust 21, 2018 1Bridge Number Pass Code (888) 793-9929 31715 2LMP, Rev M

-ADAMS ML18150A344 DG-1353 working draft

-ADAMS ML18226A212Discussion

Definition of Risk Significant and Safety Significant SSCsDefinitions of Licensing Basis Events

Guidance for a Technology-Inclusive, Risk-Informed, and Performance-Based Approach to Inform the Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors.

Combined License Applications for Nuclear Power PlantsApplications for Nuclear Power Plants

Guidelines for Preparing and Reviewing Applications for the Licensing of Non-Power Reactors

Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition

LMP Term Acronym Definition Source Terms associated with Functions Fundamental Safety Function FSF Safety functions common to all reactor technologies and designs. Includes control heat generation, control heat removal and confinement of radioactive material IAEA-TECDOC-1570 PRA Safety Function PSF Reactor design specific SSC functions modeled in a PRA that serve to prevent and/or mitigate a release of radioactive material or to protect one or more barriers to release. In ASME/ANS

-Ra-S-1.4-2013 these are referred to as "safety functions

." The modifier PRA is used in the LMP GD to avoid confusion with safety functions performed by Safety Related SSCs

. LMP, ASME/ANS-Ra-S-1.4-2013 Prevention Function

- An SSC function that, if fulfilled, will preclude the occurrence of an adverse state. The reliability of the SSC in the performance of such functions serves to reduce the probability of the adverse state.

LMP Mitigation Function

- An SSC function that, if fulfilled, will eliminate or reduce the consequences of an event in which the SSC function is challenged. The capability of the SSC in the performance of such functions serves to eliminate or reduce any adverse consequences that would occur if the function were not fulfilled.

LMP Required Safety Function RSF A PRA safety function that is required to be fulfilled to maintain the consequence of one or more DBEs or the frequency of one or more high consequence BDBEs inside the F-C Target LMP Required Functional Design Criteria RFDC Reactor design

-specific functional criteria that are necessary and sufficient to meet the Required Safety Functions LMP Safety Related Design Criteri SRDC Design criteria for SR SSCs that are necessary and sufficient to fulfill the RFDCs for those SSCs selected to perform the RSFs LMP LMP Term Acronym Definition Source Terms Associated with Licensing Basis Events Anticipated Operational Occurrence AOO Anticipated event sequences expected to occur one or more times during the life of a nuclear power plant, which may include one or more reactor modules.

Event sequences with mean frequencies of 1x10

-2/plant-year and greater are classified as AOOs.

AOOs take into account the expected response of all SSCs within the plant, regardless of safety classification.

LMP Design Basis Event DBE Infrequent event sequences that are not expected to occur in the life of a nuclear power plant, which may include one or more reactor modules

, but are less likely than AOO

s. Event sequences with mean frequencies of 1x10

-4/plant-year to 1x10

-2/plant-year are classified as DBEs.

DBEs take into account the expected response of all SSCs within the plant regardless of safety classification.

The objective and scope of DBEs form the safety design basis of the plant.

LMP Beyond Design Basis Event BDBE Rare event sequences that are not expected to occur in the life of a nuclear power plant, which may include one or more reactor modules, but are less likely than a DBE.

Event sequences with frequencies of 5x10

-7/plant-year to 1x10

-4/plant -year are classified as BDBEs. BDBEs take into account the expected response of all SSCs within the plant regardless of safety classification.

LMP Design Basis Accident DBA Postulated accidents that are used to set design criteria and performance objectives for the design of Safety Related SSCs.

DBAs are derived from DBEs based on the capabilities and reliabilities of Safety-Related SSCs needed to mitigate and prevent accidents, respectively.

DBAs are derived from the DBEs by prescriptively assuming that only Safety Related SSCs classified are available to mitigate postulated accident consequences to within the 10 CFR 50.34 dose limits.

L MP Licensing Basis Event LBE The entire collection of event sequences considered in the design and licensing basis of the plant, which may include one or more reactor modules.

LBEs include normal operation, AOOs, DBEs, BDBEs, and DBAs.

LMP Frequency-Consequence Target F-C Target A target line on a frequency

-consequence chart that is used to evaluate the risk significance of LBEs and to evaluate risk margins that contribute to evidence of adequate defense-in-depth LMP Risk Significant LBE

- An LBE whose frequency and consequence meet a specified risk significance criterion. In the LMP framework, an AOO, DBE, or BDBE is regarded as risk significant if the combination of the upper bound (95%tile) estimates of the frequency and consequence of the LBE are within 1% of the F

-C target AND the upper bound 30

-day TEDE dose at the EAB exceeds 25mrem LMP LMP Term Acronym Definition Source Terms Associated with Plant Design and Structures, Systems, and Components (SSCs)

Design Basis External Hazard Level DBEHL A design specification of the level of severity or intensity of an external hazard for which the Safety Related SSCs are design ed to withstand with no adverse impact on their capability to perform their RSFs.

LMP Plant The collection of site, buildings, radionuclide sources, and SSCs seeking a license under the LMP framework. The plant may unclude a singe reactor unit or multiple reactor modules as well as non

-reactor radionuclide sources.

LMP Multi-module Plant

- A plant comprising multiple reactor modules that are designed and constructed using a modular design approach.

. Modular design means a nuclear power plant that consists of two or more essentially identical nuclear reactors (modules) and each module is a separate nuclear reactor capable of being operated independent of the state of completion or operating condition of any other module co

-located on the same site, even though the nuclear power plant may have some shared or common systems.

Multi-module plant adapted from ASME/ANS-Ra-S-1.4-2017, modular design from 10CFR52.1

LMP Term Acronym Definition Source Safety Related SSCs SR SSCs SSCs that are credited in the fulfillment of RSFs and are capable to perform their RSFs in response to any Design Basis External Hazard Level LMP Non-Safety Related with Special Treatment SSCs NSRST SSCs Non-safety related SSCs that perform risk significant functions or perform functions that are necessary for defense

-in-depth adequacy LMP Non-Safety Related with No Special Treatment SSCs NST SSCs All SSCs within a plant that are neither Safety Related SSCs nor N on-Safety Related SSCs with Special Treatment SSCs.

LMP Risk Significant SSC

- An SSC that meets defined risk significance criteria. In the LMP framework, an SSC is regarded as risk

-significant if its PRA safety function is: a) required to keep one or more LBEs inside the F

-C Target based on mean frequencies and consequences; or b) if the total frequency LBEs that involve failure of the SSC PRA safety function contributes at least 1% to any of the LMP cumulative risk targets.

The LMP cumulative risk targets include: (i) maintaining the frequency of exceeding 100mrem to less than 1/plant year; (ii) meeting the NRC Safety Goal QHO for individual risk of early fatalit y; and (iii) meeting the NRC Safety Goal QHO for individual risk fo latent cancer fatality . LMP Safety Significant SSC

- An SSC that performs a function whose performance is necessary to achieve adequate defense-in-depth or is classified as risk significant (see Risk Significant SSC).

LMP Safety design approach The strategies that are implemented in the design of a nuclear power plant that are intended to support safe operation of the plant and control the risks associated with accidental releases of radioactive material and protection of the public and plant workers. These strategies normally include the use of robust barriers, multiple layers of defense, redundancy, and diversity, and the use of inherent and passive design features to perform safety functions LMP Terms Associated with Risk

-Informed and Performance Based Regulation and Decision Making Defense-in-Depth DID An approach to designing and operating nuclear facilities that prevents and mitigates accidents that release radiation or hazardous materials. The key is creating multiple independent and redundant layers of defense to compensate for potential human and mechanical failures so that no single layer, no matter how robust, is exclusively relied upon. Defense

-in-depth includes the use of access controls, physical barriers, redundant and diverse key safety functions, and emergency response measures."

NRC Glossary Layers-of-defense - Layers of defense are those plant capabilities and programmatic elements that provide, collectively, independent means for the prevention and mitigation of adverse events. LMP LMP Term Acronym Definition Source The actual layers and number are dependent on the actual source and hazard posing the threat. See Defense

-in-Depth LMP Term Acronym Definition Source Performance

-based decision making PB An approach that focuses on desired objective,calculable or measurable, observable outcomes, rather than prescriptive processes, techniques, or procedures. Performance

-based decisions lead to defined results without specific direction regarding how those results are to be obtained. At the NRC, performance

-based regulatory actions focus on identifying performance measures that ensure an adequate safety margin and offer incentives and flexibility for licensees to improve safety without formal regulatory intervention by the agency.

Adapted from NRC Glossary definition of performance

-based regulation in order to apply to both design decisions and regulatory decision making Risk-informed decision making RI An approach to decision making, in which insights from probabilistic risk assessment are considered with other engineering insights.

Adapted from NRC Glossary definition of performance

-based regulation in order to apply to both design decisions and regulatory decision making Terms Associated with Probabilistic Risk Assessment Initiating Event IE A perturbation to the plant during a POS that challenges plant control and safety systems whose failure could potentially lead to an undesirable end state and/or radioactive material release. An initiating event could degrade the reliability of a normally operating system, cause a standby mitigating system to be challenged, or require that the plant operators respond in order to mitigate the event or to limit the extent of plant damage caused by the initiating event. These events include human

-caused perturbations and failure of equipment from either internal plant causes (such as hardware faults, floods, or fires) or external plant causes (such as earthquakes or high winds). An initiating event is defined in terms of the change in plant status that results in a condition requiring shutdown or a reactor trip (e.g., loss of main feedwater system, small RCPB breach) when the plant is at power, or the loss of a key safety function (e.g., DHR) for non

-power modes of operation. A specific type of initiating event may be identified as originating from a specific cause as defined in terms such as "flood

-induced transient" or "seismically induced RCPB breach."

ASME/ANS-Ra-S-1.4-2013 LMP Term Acronym Definition Source Event Sequence ES A representation of a scenario in terms of an initiating event defined for a set of initial plant conditions [characterized by a specified plant operating state (POS)] followed by a sequence of system, safety function, and operator failures or successes, with sequence termination with a specified end state (e.g., prevention of release of radioactive material or release in one of the reactor

-specific release categories

. An event sequence may contain many unique variations of events (minimal cut sets) that are similar in terms of how they impact the performance of safety functions along the event sequence.

ASME/ANS-Ra-S-1.4-2013 Event Sequence Family

- A grouping of event sequences with a common or similar POS, initiating event, hazard group, challenges to the plant safety functions, response of the plant in the performance of each safety function, response of each radionuclide transport barrier, and end state. An event sequence family may involve a single event sequence or several event sequences grouped together. Each release category may include one or more event sequence families. Event sequence families are not required to be explicitly modeled in a PRA. Each event sequence family involving a release is associated with one and only one release category.

ASME/ANS-Ra-S-1.4-2014 PRA Terms (Cont'd)

End State The set of conditions at the end of an Event Sequence that characterizes the impact of the sequence on the plant or the environment. In most PRAs, end states typically include success states (i.e., those states with negligible impact) and Release Categories

. ASME/ANS-Ra-S-1.4-2014 PRA Technical Adequacy - A set of attributes that define the technical suitability of a PRA capability to provide "fit for purpose" insights to risk

-informed decision making. It includes consideration of realism, completeness, transparency, PRA model

-to-plant as-designe d and as-built fidelity state, identification and evaluation of uncertainties relative to risk levels. Strategies to achieve technical adequacy include conformance to consensus PRA standards, performance of PRA peer reviews, and structured process for PRA model configuration control, maintenance and updates, and incorporation of new evidence that comprises the state of knowledge reflected in the PRA model development and its quantification.

LMP LMP Term Acronym Definition Source Plant Operating State POS A standard arrangement of the plant during which the plant conditions are relatively constant, are modeled as constant, and are distinct from other configurations in ways that impact risk. POS is a basic modeling device used for a phased

-mission risk assessment that discretizes the plant conditions for specific phases of an LPSD evolution. Examples of such plant conditions include, e.g., core decay heat level, primary coolant level, primary temperature, primary vent status, reactor building status, and DHR mechanisms. Examples of risk impacts that are dependent on POS definition include the selection of initiating events, initiating event frequencies, definition of accident sequences, success criteria, and accident sequence quantification.

ASME/ANS-Ra-S-1.4-2014 Mechanistic Source Terms MST A source term that is calculated using models and supporting scientific data that simulate the physical and chemical processes that describe the radionuclide inventories and the time

-dependent radionuclide transport mechanisms that are necessary and sufficient to predict the source term.

ASME/ANS-Ra-S-1.4-2016 Additional Terms Implementation Guidance  ???