Attachment1.pdf

RES-07-047Official Use Only - Sensitive Internal Information

Official Use Only - Sensitive Internal Information

OFFICE OF NUCLEAR REGULATORY RESEARCH

STATEMENT OF WORK

RES-07-047

TITLE: Review and Analysis of Operational Events for Accident Sequence Precursors

I. BACKGROUND

The U.S. Nuclear Regulatory Commission (NRC) established the Accident Sequence Precursor (ASP) program in 1979. The primary objective of the ASP program was and continues to be the systematic evaluation of the risk-significance of U.S. commercial nuclear power reactor operational events.

The ASP program’s prime objective is met by the identification, documentation, and ranking of those reactor operating events that are most likely to lead to inadequate cooling of the fuel in the reactor core and severe fuel damage (precursors), if additional failures had occurred. To accomplish this objective the staff of the NRC’s Office of Nuclear Regulatory Research (RES), with contractor assistance, reviews event and condition reports received from various sources.

Based on these reviews, the RES staff selects those occurrences that are identified as potential precursors for further analysis. The NRC staff or the contractor will then complete a detailed analysis of the selected occurrences, including the calculation of a conditional core damage probability (CCDP). The detailed analysis includes mapping failures observed during the event or condition into risk model accident sequences. CCDP is calculated directly for an event or as a change in core damage probability (ΔCDP or importance) for a condition. An event or a condition with a CCDP greater than or equal to 1.0 x 10-6 is considered a precursor in the ASP program.

The ASP program also has secondary objectives of:

• Categorizing the precursors by their plant-specific and generic implications

• Providing a measure for trending nuclear plant core damage risk

• Providing a partial check on dominant core damage scenarios predicted by probabilistic risk assessments (PRAs).

The NRC also uses the results of the ASP Program to monitor performance against the safety goal established in the agency’s Strategic Plan. (See NUREG-1100, Vol. 21, dated February 2005.) Specifically, the program provides input to the following performance measures:

• Zero events per year identified as a significant precursor of a nuclear reactor accident (i.e., CCDP or ΔCDP greater than or equal to 1 x 10-3).

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• No more than one significant adverse trend in industry safety performance with no trend exceeding Abnormal Occurrence Criterion I.D.4.

A detailed description of the ASP program and process is provided in Attachment A.

II. OBJECTIVE

The primary objective of the efforts described in this statement of work (SOW) is to systematically evaluate U.S. nuclear plant operating experience to identify and document the operating events that were most likely to lead to inadequate core cooling and severe core damage (precursors), if additional failures had occurred. Using standardized plant-specific models provided by the NRC, the contractor shall perform detailed risk analyses of events or conditions that have occurred during all phases of reactor operations. Additionally, the contractor shall perform Large Early Release Frequency (LERF) analyses when requested for selected events, again using models provided by the NRC. The contractor shall also provide technical on-call support to NRC staff for in-house analysis of other operating events.

III. WORK SCOPE

The tasks of this SOW cover the systematic evaluation of potentially significant operational experience of U. S. commercial nuclear power plants. The evaluations are intended to identify, assess, and rank potentially serious operational occurrences or conditions. The ASP evaluations are probabilistic and produce a quantitative measure of significance. The significance measure is the conditional probability of the analyzed event or condition resulting in reactor fuel damage. The occurrences to be evaluated primarily span the calendar years from 2007 through 2011 and come from Licensee Event Reports (LERs) and NRC inspection reports.

A few "special" operational events (including events from prior years) as identified by the NRC’s Project Monitor(PM) for this contract may be evaluated each year.

The tasks specified below are designed to provide timely, systematic, and consistent evaluations of operational experience and documentation of precursor event analysis results.

Attachment B depicts a suggested time line for the various tasks. Since the analysis requires the use of specific models, familiarization training with the applicable models is provided.

III.1. TASK 1 - SCREENING AND ENGINEERING EVALUATION

The contractor shall obtain copies of the LERs in electronic format from the NRC’s Agencywide Document Access and Management System (ADAMS). The engineering evaluation (screening) of each LER shall be accomplished within two months of the LER being available in ADAMS, or sooner at the direction of the PM. The contractor shall initially evaluate all operational experience data obtained from ADAMS or provided by NRC Project Manager (PM). This engineering evaluation is a bounding review with the goal of eliminating those events that are clearly not important from a risk perspective and identifying those events that require further analysis as potential precursors.

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This engineering evaluation will assess the significance of the event or condition described in the documentation with respect to being a precursor to potential severe core damage. The review shall judge whether the event should be considered for further analysis (Task 2) based on the reviewer(s) knowledge of nuclear plant operations and specific plant configurations, and the event’s associated potential to lead to a loss of core cooling and subsequent severe fuel damage.

Any event that clearly meets the ASP program criteria for further analysis should be identified for analysis as a potential precursor as input to the process specified in Task 2. Any event that the reviewer cannot readily reject or classify as a potential precursor must be reviewed by at least one other reviewer before a decision is made on whether or not the event requires a more detailed analysis.

III.1.1 Data Sources: The main sources of operational events furnished by the NRC to the contractor will be LERs and NRC inspection reports.

1. LERs. The primary source of events will be LERs identified as potential precursors by a screening process conducted by contractor. The contractor shall screen every new LER. If problems arise in obtaining copies of the LERs, the contractor shall notify the NRC PM, who will assist in resolving the problem.

2. NRC inspection reports. The secondary source of event information will be NRC inspection reports. The NRC PM will provide the contractor with electronic copies of the inspection reports which are pertinent to potential precursors (e.g., reports that contain findings that were evaluated to be greater than “green” via the Significant Determination Process (SDP). For further information on the color of the findings, refer to:

http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/index.html.

The contractor shall obtain copies of these reports in electronic format from ADAMS. If problems arise in obtaining copies of the inspection reports, the contractor shall notify the PM, who will assist in resolving the problem.

3. Other sources. In addition to the review of LERs and inspection reports for candidate precursors, it is anticipated that there will be a few special events which will require evaluation. The NRC PM will identify these events and provide the information necessary to conduct the equivalent ASP evaluation.

III.1.2 Reviewer Experience: This review task shall be performed by persons that have considerable knowledge and experience in the following areas:

- Nuclear power plant system design and operation

- Nuclear power plant response to various transient and accident initiators, including recovery measures which might be pursued to mitigate the impact of the specific initiator

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- Practical and demonstrated experience with the screening and review of operational experience data from a variety of sources such as LERs, Institute of Nuclear Power Operations’ Equipment Performance Information Exchange (EPIX) component failure records, NRC inspection reports, etc.

- NRC’s regulations and the industry’s reporting criteria such as 10 CFR 50.72 “Immediate Notification Requirements for Operating Nuclear Power Reactors,” 10 CFR 50.73 “Licensee Event report system,” and NUREG-1022 Rev. 1 “ Licensee Event report System.”

III.1.3 Engineering Evaluation Criteria: Identification of candidate precursors requires the review of operational events for instances in which plant functions that provide protection against fuel damage have been challenged or compromised. Previous experience with reactor plant operational events has shown that most operational events can be directly or indirectly associated with four initiators:

1. Reactor scrams (BWRs)/trips (PWRs) [which includes loss of main feedwater (LOFW) within their sequences],

2. Loss of offsite power (LOOP),

3. Loss of coolant accidents (LOCAs), and

4. Steam generator tube rupture (SGTR) [pressurized-water reactors (PWRs) only].

These four initiators are primarily associated with loss of core cooling. ASP program members, including NRC staff and contractors, examine LERs and other events documentation to determine the impact that operational events on potential core damage sequences associated with these initiators. Operating events are occasionally identified that impact other initiators, such as an in-plant fires, in-plant flooding, seismic events, and tornadoes. The NRC currently has external events PRA models for some plants. Unique models may have to be developed for other plants to address events not currently included in the NRC models.

III.1.4 Screened Events: Conditions and events are eliminated from further analysis consideration as potential precursors if they involved only one of the following:

1. A component failure with no loss of redundancy and no scram/trip,

2. A short-term loss of redundancy in only one system, except for support system failures of a single system identified in the Potential Precursor section below,

3. An event that occurred prior to initial criticality,

4. Design or qualification error that is small relative to what is predicted (e.g., an error of a few percent in an actuation set point), Official Use Only - Sensitive Internal Information

5. An event bounded by a scram/trip with LOFW,

6. An event with no appreciable impact on safety systems, or

7. An event involving only post-core-damage impacts.

In general, an ASP event will include any event in which systems were unavailable or very likely to be unavailable so as to cause transient response complications or a degraded level of safety for responding to an accident. More specifically:

The following three categories of events are necessarily screened as potential ASP events, irrespective of operational status:

1. Loss of Coolant Accident (leakage is beyond Technical Specification limits)

2. Steam Generator Tube Rupture (with measurable leakage)

3. Loss of Offsite Power (any one EDG demanded to reenergize safety bus) (reject if shutdown and fuel cooling is not affected)

For other events:

If no scram or transient occurs during the event:

Generally follow Safety System Failure (SSF) coding guidelines (see Precursor definitions and Threshold in Appendix A) for those systems associated with scram/transient response (not to include containment, H2 control, etc.)

For potential SSFs, user coder judgement to determine the relative likelihood of the failure occurring during anticipated transients (LOOP, LOFW, etc.)

If an LER lists multiple systems or trains that are in a reduced state of redundancy or operability (systems that prevent core damage), include as an ASP even if SSF criteria are not met

If a scram or transient occurs during the event:

Include any situation where one or more trains of safety systems associated with the transient response are not available or fail to function as required. Note that this is a more strict criteria than those above.

The tabulation in Attachment C provides a summary listing of the types of events currently being rejected from further analysis. Changes in the rejection criteria shall be identified to eliminate from further analysis consideration as potential precursors and shall be approved by the NRC PM prior to implementation.

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III.1.5 Potential Precursors: Events identified for further analysis as potential precursors typically include the following:

1. Core damage initiators (e.g., LOOP, SGTR, and small-break LOCA),

2. All events in which a scram/trip was demanded and a safety-related component failed,

3. All support systems failure, including failures in cooling water systems, instrument air, instrumentation and control, and electric power systems.

4. Any event in which two or more failures in mitigation systems occurred,

5. Any event or operating condition that was not predicted or that proceeded differently from the plant design basis,

6. Any event that, based on the reviewers’s experience, could have resulted in or significantly affected a chain of events leading to potential severe core damage, and

7. Any inspection finding with a greater than “green” color for the final significance determination.

III.1.6 Other Event Categories In addition to rejected events and candidate precursors, the engineering evaluation may result in an event being identified as one of three “Other Event Categories.” The “Other Event Categories” are:

S Containment-Related (Other) Events - These are events that involve the loss or potential loss of containment functions [i.e., containment cooling, containment spray, containment isolation (direct paths to the environment only), or hydrogen control]. Containment Related (CR) events are not currently considered precursors as defined by the ASP program: however, the potential for an increased in LERF metric warrants their identification. It is estimated the two events per year that warrant LERF quantification.

S Potentially Significant (Other) Events Considered Impractical to Analyze - These events are capable of impacting core damage sequences, but they involve component degradations in which the extent of the degradation could not be determined, or the impact of the degradation on plant response could not be ascertained. Potentially Significant (PS) events are not considered precursors as defined by the ASP program, however, their potential core damage impact warrants their identification.

S Interesting (Other) Events - These events usually do not meet the criteria for a precursor, but they provide insight into unusual failure modes with the potential to compromise continued core cooling. Interesting (I) events are not considered precursors as defined by the ASP program: however, their potential to affect core cooling warrants their identification.

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Events identified in these other categories are not considered precursors as defined by the ASP program.

III.1.7 Reporting Requirements: The results of the screening evaluation (Task 1) shall be provided to NRC PM within a week after each screening and evaluation. The results of Task 1 also shall be documented in the Monthly Letter Status Report (MLSR). More specific reporting requirements areas follows:

III.1.7.1 Event Status Table - An Event Status Table (Attachment C) shall be included in the MLSR. This table documents and tracks the results of the screening efforts, including the disposition of each event processed in Tasks 1 through 3. The information to be included in the table shall comply with the information requested and codes shown in the form and table of Attachment C. The codes shown in Attachment C have been established for use in this tabulation to describe the evaluation result reasons. This helps to facilitate documentation of the screening efforts. Those events requiring a second reviewer during the evaluation process shall be annotated in the Event Status Table. When an event requires no further processing (i.e. rejected/other) subsequent table columns shall be shaded dark. Rejected events shall only be identified in one issue of the table and subsequently be removed to reduce the length of the table while maintaining an accurate representation of all events currently within the process.

The bottom of the Event Status Table should reflect the following fiscal year (FY) totals (by event date) for Task 1:

1. FY number of events screened out

2. FY number of event evaluations completed and rejected

3. FY number of other event evaluations completed

4. FY number of event evaluations completed and continued (differentiate NRC/Task 2 continuance), and

5. FY number of events received and the evaluations are not completed, i.e.“in process.”

III.1.7.2 Other Event Documentation - Containment-Related, Potentially Significant but Impractical to Analyze, and Interesting Events shall be identified in the Event Status Table and documented in the MLSR with the following information:

1. Other event summary and description

2. Basis for categorization

3. Factors of Interest

4. References

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III.1.7.3 Monthly Evaluation Cost Tracking Table or Graph - Included in the MLSR shall be a table laying out detailed analysis and quantification for Task 2 analysis per event and the quantity of events analyzed. The table shall identify the most recent 12 months and shall include LER number, plant name, a short description of each event, charges occurred during each reporting period, and cumulative charges for each event. Or, included in the MLSR shall be a combined line/bar graph depicting the monthly average cost for Task 2 analysis per event and the quantity of events analyzed. The x-axis shall identify the most recent 12 months. The left y-axis shall identify dollars/event analyzed. A height of a single vertical bar for each month shall depict that month’s average analysis cost per event. A horizontal dashed line shall depict the cost per event analyzed that the contractor’s proposal was based upon. A text note on the graph shall depict a running cost/event average for all months of that contact year depicted on the graph thus far, (i.e. average of all vertical bars). The right y-axis shall identify the number of events evaluated. Monthly points shall be plotted and connected by a line depicting the quantity of events analyzed each month.

III.1.8 Schedule: The engineering evaluation of an event shall be completed within two work weeks of identifying the documentation of the event from either in the ADAMS by contractor or

NRC PM.

III.1.9 Results: The results of the screening and engineering evaluation process for all event categories shall be provided to the NRC PM within a week. The NRC PM will then develop and provide a listing of those events that the contractor shall process further. The screened and the “Other Event Categories” events will require no further contractor consideration or processing.

III.2 TASK 2 - DETAILED ANALYSIS & QUANTIFICATION

The contractor shall perform a detailed analysis and quantification of each of the assigned potential precursors identified in Task 1 and those special events identified by the NRC PM.

The contractor shall quantify an event by using the appropriate Standardized Plant Analysis Risk (SPAR) model. Event quantification shall include determination of the conditional probability of severe core damage given the failures or conditions occurring during an event.

III.2.1 Experience Requirements: This task shall be performed by persons that have expert knowledge and experience in the following areas:

- Nuclear power plant system design and operational performance

- Nuclear power plant emergency operating procedures

- Probabilistic risk assessment (PRA), including familiarity with PRAs, models (Level 1:

internal events models, external events models, low power and shutdown models; Level 2: LERF models), individual plant examinations (IPEs), and individual plant external event examinations (IPEEEs)

- Application of PRA techniques to assess operational experience

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- Construction and review of system fault trees and event trees

- PRA computer codes [i.e., Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE).

- Human reliability analysis methods (e.g., SPAR-H Method)

III.2.2 Analysis Criteria: Each analysis considers the immediate impact of an initiating event, or the potential impact of the equipment failures or operator errors, on the readiness of systems in the plant to mitigate off-normal and accident conditions. In the review of each selected event, four general scenarios (involving both the actual event and postulated additional failures) are considered.

1. If the event or failure was immediately detectable and occurred while the plant was at power, then the event is analyzed according to the likelihood that it and the ensuing plant response could lead to severe core damage.

2. If the event or failure had no immediate effect on plant operation (i.e., if no initiating event occurred), then the review analyzes whether the plant would require the failed items for mitigation of potential severe core damage sequences, should a postulated initiating event occur during the failure period.

3. If the event or failure resulted in an automatic reactor trip and occurred while the plant was at power, then the event is evaluated according to the likelihood that it and the ensuring plant response could lead to core damage.

4. If the event or failure was identified while the plant was not at power, then the event is first assessed to determine whether it could have impacted at-power operation. If the event could have impacted at-power operation, its impact is assessed. If the event could only occur during shutdown, then its impact on decay heat removal during shutdown is assessed.

For each actual occurrence or postulated initiating event associated with an operational event, the sequence of operation of various mitigating systems required to prevent core damage shall be considered. Events are selected and documented as accident sequence precursors (i.e., precursors to potential severe core damage accidents) if the CCDP is at least 1.0 x 10-6.

For degraded conditions or significant operational occurrences for which the NRC PM determine there is an SDP or documented Incident Investigation Program (MD 8.3) quantitative risk evaluation, the ASP program will utilize the results of these evaluations, where applicable, without performing a separate ASP analysis. The contractor shall continue to perform analyses for those events for which there is no SDP or MD 8.3 evaluation. Examples of these types of events include most initiating events and plant conditions where there are no performance deficiencies. In addition, in cases where there are concurrent multiple degraded conditions, the ASP process shall perform an analysis to evaluate the risk of these conditions taken together.

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The analysis is not limited to the information in the LER or other documentation provided by the NRC PM. The analyst shall use Final or Updated Safety Analysis Reports (FSARs or USARs), IPEs, NRC inspection reports, and any other available documented information about the event or condition.

III.2.3 Method: Quantification of ASP significance involves determination of a conditional probability of subsequent severe core damage given the failures observed during an operational event. This probability is estimated by mapping failures observed during the event onto the ASP accident sequence models (SPAR models modified to reflect the event), which depict potential paths to severe core damage, and calculating a conditional probability of core damage.

The effect of a precursor is assessed by reviewing the operational event specifics against system design information. This information is used to modify the SPAR model. Quantification results in a revised conditional probability of core damage given the operational event. The conditional probability estimated for each candidate precursor is useful in ranking because it provides an estimate of the measure of protection against core damage that remains once the observed failures have occurred. The CCDP during the time period in which the failures were observed is used to rank the initiating event assessments. The importance measure, the difference between the CCDP and the nominal CDP for the same period of time, is used to rank the unavailability assessments.

For most events that meet the ASP program selection criteria, the observed failures significantly impact the core damage model. In these cases, there is little numeric difference between the CCDP and the importance measure that was previously used (CCDP - CDP). For some events, however, the nominal plant response during the time period dominates the results. In these cases, the CCDP can be considerably higher than the importance measure (the impact of such a condition on plant response is relatively minor). By only looking at the CCDP for such a event, its significance may be overestimated. Therefore, for condition assessments, the CCDP, the CDP, and the difference between these values (i.e., the importance) are determined. The frequencies and failure probabilities used in the calculations are derived in part from data obtained across the population of light water reactors (LWRs).

III.2.4 Event Rejection criteria : Conditions and events are rejected as potential precursors are:

S A component failure with no loss of redundancy and no scram/trip, S A short-term loss of redundancy in only one system, except for support system failures of a single system identified in the Potential Precursor section, S An event that ΔCDP or CCDP is less than a scram/trip with LOFW, S The ΔCDP or CCDP less than 1E-06.

S Loss of redundancy in only one system, except for support system, that can be detected between two surveillance tests.

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III.2.5 Additional Information: If additional information is required to perform the analysis, especially that obtainable from licensees, the contractor shall notify the NRC PM (via telephone call, with a follow up by e-mail) delineating the specific information and the reason this information is needed. The NRC PM will coordinate the necessary activities to obtain this information, nominally within two work weeks (i.e., 10 work days).

III.2.6 Reporting Requirements: The results of Task 2 shall be documented in the MLSR as follows:

III.2.6.1 Rejected Events Documentation - Brief individual reports shall be contained in the MLSR that explain the reason(s) for the rejection of each analyzed event under this task.

Frequently utilized reasons shall also be depicted on the Event Status Table as a rejection code. For brevity involving unique event rejection reasons, the Event Status Table may simply refer to the individual report for the rejection reason.

III.2.6.2 Monthly Analysis Cost Tracking Table - Included in the MLSR shall be a table laying out detailed analysis and quantification for Task 2 analysis per event and the quantity of events analyzed. The table shall identify the most recent 12 months and shall include LER number, plant name, a short description of each event, charges occurred during each reporting period, and cumulative charges for each event. Or, included in the MLSR shall be a combined line/bar graph depicting the monthly average cost for Task 2 analysis per event and the quantity of events analyzed. The x-axis shall identify the most recent 12 months. The left y-axis shall identify dollars/event analyzed. A height of a single vertical bar for each month shall depict that month’s average analysis cost per event. A horizontal dashed line shall depict the cost per event analyzed that the contractor’s proposal was based upon. A text note on the graph shall depict a running cost/event average for all months of that contact year depicted on the graph thus far, (i.e. average of all vertical bars). The right y-axis shall identify the number of events evaluated. Monthly points shall be plotted and connected by a line depicting the quantity of events analyzed each month.

III.2.7 Schedule: Each event analysis shall be completed within seven work weeks of receiving the event from the NRC. However, if additional information regarding the event is required from the licensee before the analysis can be completed, an additional four work weeks will be allowed for the licensee to provide a response to the request. In the event that this time is insufficient, the contractor shall notify the NRC PM so that a revised schedule for completion of the analysis may be generated. It is anticipated that the NRC’s time between Task 1 and Task 2 will be one work week to notify the contractor as to which events continued from Task 1 will be analyzed by the contractor in Task 2. The seven work week schedule for this task includes the time for Task 1 evaluation, NRC authorization for Task 2 analysis, and the Task 2 analysis .

III.2.8 Results: The results of the preliminary precursor analysis process for non-rejected events shall be noted in the MLSR and documented in reports as specified in Task 3.

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III.3 TASK 3 - ANALYSIS AND QUANTIFICATION DOCUMENTATION

The results of the analysis and quantification efforts shall be documented in letter reports. Two letter report versions shall be prepared for each preliminary analysis from Task 2 that was either

(1) not rejected or (2) rejected as an ASP precursor but had an inspection finding that was not Green. The first version is known as the preliminary report and the second version is known as the final report.

The goal of each report is to document the analysis, quantification, and the reasons for the classification of the associated event. Each report must be sufficient to allow a knowledgeable reader to understand the key elements of the analysis, (i.e., sequence of events, equipment malfunctions, human errors, the bases for probability evaluations, key assumptions, and areas of uncertainty.)

III.3.1 Preliminary Precursor Analysis Reports

Detailed analysis and quantification documentation of each event shall begin with an initial draft preliminary analysis report. This report shall be submitted to the PM for RES sponsor comment.

The format for this report shall follow the example contained in Attachment D.

The NRC PM will provide the contractor with copies of the RES sponsor comments as they are received. The contractor shall develop proposed resolutions to the comments and discuss them with the NRC PM prior to making significant changes to either the analysis or the draft report.

The second draft shall incorporate changes as agreed upon by the NRC PM that reflect the resolution of all the comments on the initial draft. Additionally, each comment and its associated resolution shall be summarized in an attachment to the second draft. The NRC anticipates ten working days will be required to develop comments on each initial draft document.

III.3.1.1 Schedule: The preliminary precursor report documentation for an event shall be completed within nine work weeks of the NRC assign of event to the contractor. This nine work-week period includes preparation of both the initial and second draft reports, engineering evaluation (Task 1), the detailed analysis and quantification (Task 2), and a two work week period for the NRC sponsor to review comment on the initial draft.

III.3.1.2 Results: Develop and produce first and second preliminary precursor analysis reports for each precursor identified by Task 2. The second draft shall incorporate NRC approved modifications to the first draft as required to incorporate responses to RES sponsor comments.

Progress on the development of these reports shall be tracked in the Event Status Table.

III.3.2 Final Precursor Analysis Reports

Development of each final precursor analysis report begins with the release of the second draft preliminary precursor analysis report (Task III.3.1) for both internal and external peer review.

Two draft final precursor analysis reports are anticipated to be needed to properly reflect and

Official Use Only - Sensitive Internal Information incorporate changes resulting from the peer review comments. The second of these drafts will be issued as the final precursor analysis report for the associated event.

III.3.2.1 Method: The NRC PM will distribute the second draft preliminary precursor analysis documents for both internal and external peer review. The NRC PM will gather the comments and provide copies and discuss each comment with the contractor as they are received (licensee and public review comments will also be solicited for cases where the CCDP or ΔCDP is greater than1 x 10-4). The contractor shall review the comments and prepare proposed responses to the comments for review and approval by the NRC PM. With the assistance of the NRC PM, the contractor shall obtain any additional information needed to satisfactorily address the comments. Upon approval of the NRC PM, the contractor shall perform all analyses that are necessary to address the comments and revise the associated draft reports.

As part of the submittal of both final draft reports, the contractor shall include an attachment which details each comment and its resolution. Resolutions to comments shall be discussed with the agency prior to making significant changes to the analysis and/or preliminary report.

III.3.2.2 Schedule: Receipt of comments on each second draft preliminary precursor analysis report (Task III.3.1) is anticipated, on average, to take 30 work days after the draft has been distributed for comment. The first draft final precursor analysis report which incorporates the resolution of these comments shall be completed and submitted to the NRC PM within 15 work days after receipt of all comments. Anticipate ten work days for receipt of NRC comments on this draft. The second draft final precursor analysis report shall be completed and submitted as the final report to the NRC PM within two work weeks after receipt of these comments on the initial draft of the final report.

III.3.2.3 Results: Develop and produce two draft final precursor analysis reports for each precursor identified in Task 2. The reports shall include documentation of all comments and their ultimate resolutions received on these final precursor analysis reports. Progress on the development of these reports shall be tracked in the Event Status Table.

III.4 Task 4. INDEPENDENT REVIEW OF ASP ANALYSIS PERFORMED BY OTHERS

As part of the quality assurance for this program, the NRC PM shall periodically provide the contractor with copies of ASP analyses performed by others such as the NRC staff. The contractor shall perform a review of the analysis documentation to assure that all current rules and guidelines have been followed and the results are consistent with other analyses. Any discrepancies or problems shall be discussed with the NRC PM. All efforts and resolutions shall be summarized in the MLSR.

III.4.1 Schedule: Reviews shall be completed and results discussed with the NRC PM within three weeks after receipt of each analysis.

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III.4.2 Results: Provide comments on the accuracy and consistency of each ASP analysis review. Document the results in the MLSR.

III.5 TASK 5 TECHNICAL ASSISTANCE

During the course of this project, technical assistance to NRC staff may arise on specific problems associated with efforts covered by this entire scope of work. These efforts are normally high-priority, quick-turnaround items. Efforts requiring more than approximately 30 minutes may only be undertaken only after permission is received from the NRC PM.

Information on each request shall be tabulated in the MLSR. The tabulation shall include the requester’s name and affiliation, the request date, the subject area of the problem, the approximate time required to respond, the response date, and a brief summary of the results.

III.5.1 Schedule: Responses to technical assistance requests shall be completed as soon as possible after receipt. However, responses shall not delay the completion efforts associated with Task 1 through Task 4.

III.5.2 Results: Provide responses to technical assistance requests as they are received.

Document the responses in the MLSR.

III.6 TASK 6 - TECHNICAL MANUAL MAINTENANCE

The contractor shall update and maintain a reference technical manual (known as the Risk Assessment Standardization Project (RASP) handbook) for the ASP program. The contractor will be provided with the master copy of the original manual.

The master copy shall be informally updated continually as problem resolutions and program enhancements are identified (either by the contractor or other ASP analysts), approved by the NRC PM and implemented. Revisions may include, for example, corrections, additional examples, clarification of existing guidance, and development of new guidance and tutorials.

Copies of these changes shall be provided to the NRC PM as they are made. At least annually, the changes shall be reviewed and complied and formally distributed (either in printed form or electronically) to all of the registered copy holders. All changes and distributions shall be documented in the MLSR.

III.6.1 Schedule: Changes to the process resulting in updates to manual shall be documented and provided to NRC PM within two weeks after being identified. The NRC PM shall provide comments within two work weeks after receipt of the draft. The updated manual, incorporating the approved changes shall be distributed within six work weeks after the start of each fiscal year.

III.6.2 Results: provide and distribute an ASP program reference technical manual. Issue annual updates. Document the changes and distribution in the MLSR.

III.7 TASK 7 - PROBLEM IDENTIFICATION

Any problems encountered using the SAPHIRE codes or the SPAR models shall be discussed with the NRC PM and documented in the MLSR. The documentation shall describe in detail the problem or difficulty encountered and the steps taken to resolve the problem, including coding manual guidance changes, code changes, and model updates.

III.7.1 Schedule: Problems or difficulties encountered when using the SAPHIRE codes or the SPAR models shall be brought to the attention of the NRC PM as they are identified. The notification can be by telephone or e-mail. Follow-up documentation shall be completed in the next scheduled MLSR.

III.7.2 Results: Problems encountered with the use of the SAPHIRE codes or the SPAR models shall be documented in the MLSR.

III.8 TASK 8 - ANALYSIS AND QUANTIFICATION OF SPECIFIED PLANT CONDITIONS

AND ISSUES

The contractor shall perform a probabilistic risk analysis and quantification for specified plant conditions or specified plant issues (e.g., generic issues) or provided by NRC PM. The parameters for the risk assessments shall be provided by the NRC PM. The contractor shall evaluate the risk significant of issues and conditions using SPAR models. It is estimated six specified plant conditions or issues per year.

III.8.1 Method: Evaluation of specified plant conditions and issues involve determination of a conditional probability of subsequent severe core damage or large early release of radioactivity given the specified conditions or issues. This probability is estimated by mapping the postulated failures and conditions onto the SPAR models (SPAR models modified to reflect the event), which depict potential paths to severe core damage, or early release. The risk significance is assessed by reviewing the plant condition or issue against nominal or desired system design. This information is used to modify the SPAR model. Quantification of the revised risk model will provide an estimate of the change in the risk from the occurrence of the plant condition or issue.

Detailed documentation of each specified condition shall begin with an initial draft preliminary analysis report. This report shall be submitted to the PM for review and comment. The format for this report shall be specified by the NRC PM. The NRC PM will provide the contractor with copies of the NRC comments as they are received. The contractor shall develop proposed resolutions to the comments and discuss them with the NRC PM prior to making significant changes to either the analysis or the draft report. The second draft shall incorporate changes as agreed upon by the NRC PM that reflect the resolution of all the comments on the initial draft.

Additionally, each comment and its associated resolution shall be summarized in an attachment

Official Use Only - Sensitive Internal Information to the second draft. The NRC anticipates ten working days will be required to develop comments on each initial draft document.

III.8.2 Schedule: The preliminary report documentation for a specified event shall be completed within nine work weeks of the NRC assignment of task to the contractor. This generally nine work-week period includes preparation of both the initial and second draft reports and a two work week period for the NRC to review on the initial draft

III.8.3 Results: Develop and produce first and second analysis reports for each specified condition identified by Task 8. The second draft shall incorporate NRC approved modifications to the first draft as required to incorporate responses to NRC comments. Progress on the development of these reports shall be tracked in the Event Status Table.

IV. REPORTING REQUIREMENTS

Monthly Letter Status Report: Work efforts, progress, problems/resolutions, and plans for the next period in each of the above task areas shall be documented an MLSR. This report shall also include a current financial status report as well as the additional information specified by the individual tasks contained in the SOW. This includes:

1. An Event Status Table (containing information from Task 1 thorough 3)

a. Events designated for task 1 review by NRC, including screened out and potentially significant events.

b. ASP events status table for Task 2, include Event LER or inspection report number, plant name, LER title or short description, event date, event received, duration, and status during each reporting period.

2. Summary of Containment-Related, Potentially Significant, not Significant Potentially Significant but impractical to Analyze and Interesting Events (Task 1)

3. Monthly Cost Tracking Tables (Tasks 1, 2 and 8)

a. Detailed cost incurred during each reporting period

b. Expenditures and invoice tables.

b.1 Expenditures table shall reflect planned and actual monthly expenditures b.2 Invoice table shall show the planned and actual amount invoiced for each month and shall include billing delays

4. Summary of Screened out Events (Tasks 1 and 2)

Official Use Only - Sensitive Internal Information

5. Summary of Results for Independent Review of ASP Analyses Performed by Others (Task 4)

6. Documentation of Responses to Technical Assistance Requests (Task 5)

7. Maintenance of a Technical Reference Manual (Task 6)

8. Problems encountered with the use of the SAPHIRE codes or the SPAR models

(Task 7)

V. DELIVERABLES AND DELIVERY SCHEDULE

The contractor shall prepare each deliverable as summarized below and provide copies to the NRC Project Manager and the NRC PM and other NRC staff as specified in an list of addressees that will be provided prior to the first MLSR. The deliverables should be transmitted in both hard copy and electronic copy form.

V.1 Monthly Letter Status Report Due at the NRC Headquarters by the 15th of every month.

V.2 Task 1 - Screening and Engineering Evaluation See Monthly Letter Status Report

The engineering evaluation (screening) of each LER shall be accomplished within two months of the LER being available in ADAMS or provided by NRC PM, or sooner at the direction of the PM. The results of these evaluations shall be documented in the MLSR. The results shall be provided to NRC PM after screening and engineering evaluation.

V.3 Task 2 - Detailed Analysis and Quantification

1. Work plan for each assigned event 1 week after assigned of the event by NRC PM

2. Preliminary analysis results documentation See Monthly Letter Status Report

Preliminary analysis of each assigned event shall be completed within seven weeks of the notification that the contractor’s shall perform the detailed analysis and quantification. The results of each analysis shall be documented in the MLSR. Further detailed documentation of events not rejected as a result of this analysis is covered under the deliverable requirements detailed in Task 3, below.

V.4 Task 3 - Analysis and Quantification Documentation See Monthly Letter Status Report

Progress on the development of the documentation of precursor reports shall be included in the MLSR. Specific requirements for each of the report versions are as follows:

Official Use Only - Sensitive Internal Information

V.4.1 Preliminary Precursor Analysis Reports

1. 1st draft Preliminary Precursor Analysis Report of an event 8 weeks after receipt of the event

2. 2nd draft Preliminary Precursor Analysis Report of an event 10 weeks after receipt of the event.

V.4.2 Final Precursor Analysis Document

1. Draft Final Precursor Analysis Document of an event 3 weeks after contractor’s receipt of comments

2. Final Precursor Analysis Document issued 2 weeks after receipt of agency’s comments on draft Final Precursor Analysis Document

V.5 Task 4 - Independent Review of ASP See Monthly Analysis performed by Others Letter Status

Report

V.6 Task 5 - Technical Assistance See Monthly Letter Status Report

V.7 Task 6 - Technical Manual Maintenance See Monthly Letter Status Report

Annual Manual Update Six weeks after start of each Fiscal year

V.8 Task 7 - Problem Identification See Monthly Letter Status

Official Use Only - Sensitive Internal Information

Report

V.9 Task 8 - Analysis and Quantification of Specified Conditions

1. Work plan for each assigned event 1 week after assigned of the event by NRC PM

2. Preliminary analysis results documentation See Monthly Letter Status Report

3. Draft Final Analysis Document of an event 3 weeks after contractor’s receipt of comments

4. Final Analysis Document issued 2 weeks after receipt of agency’s comments on draft Final Analysis Document

Any problems identified in the model familiarization training or use shall be described in detail in the MLSR. The discussion shall include the steps taken to resolve the problem.

VI. FAMILIARIZATION TRAINING

VI.1 Initial Training

This subtask provides support for the contractor’s project staff to familiarize themselves with the appropriate SPAR models and training for using the SAPHIRE suite of computer codes and these models. The analysis efforts conducted under this work statement require the use of the NRC PRA (SPAR) models. Currently, the SPAR model library includes 72 Level 1 models for at power internal events. SPAR models for external events (e.g., in-plant fire, seismic, tornado), low power and shutdown operation, and Level 2 (LERF) are being developed. These models are designed for use with the NRC SAPHIRE suite of PRA computer codes.

The 5-day training will be a one time course sponsored by the NRC at the beginning of the contract. The course shall be conducted approximately six weeks following the award of the contract. The actual dates will be agreed upon by the NRC PM and the contractor. The actual dates will also be contingent on the availability of the appropriate NRC training facilities.

Additional 5-day training courses can be provided by the NRC but all expenses shall be borne by the contractor.

Detailed on-the-job training for new contractor analysts as they are assigned to the project shall be the responsibility of the contractor. However, the NRC will provide training assistance if requested and agreed to by the NRC PM.

VI.2 Annual Counterparts Meeting

Official Use Only - Sensitive Internal Information

This subtask provides annual refresher training to the contractor’s project staff on new analysis methods, SPAR model and SAPHIRE enhancements, and a review of new sections of the ASP Technical Manual. The meeting will provide a forum for NRC and Contractor analysts to exchange experiences and lessons learned during the past year.

The 2-day training will be sponsored by the NRC during the second, third and forth year of the contract. The course will be conducted at the NRC headquarters in Rockville, Maryland. The actual dates will be agreed upon by the NRC PM and the contractor. The actual dates will also be contingent on the availability of NRC sponsored guest speakers.

VII. MEETINGS AND TRAVEL

Beside the travel for initial training and annual counterpart meetings, the contractor shall plan for two trips by two staff members to NRC headquarters in Rockville, Maryland, each year of the contract. The meeting should be scheduled for two days, with the main purpose being to brief the NRC staff on the progress and status of the project. Additional travel may be authorized after consultation and agreement with the NRC PM.

VIII. Applicable Special Provisions

The staff working on this project shall have demonstrated, detailed knowledge of and experience with the analysis of operational events for accident sequence precursors.

The key project staff must also have extensive practical experience in the construction and review of system fault trees and event trees and be familiar with published probabilistic risk assessments (PRAs) and individual plant examinations (IPEs).