Text

OEDO-15-00641 DPO-2015-001 on the Significance Determination Process Evaluation for a Finding at Arkansas Nuclear One Involving the March 2013, Unit 1 Stator Drop Event, Redacted-Public
	ML16061A362
Person / Time
Site:	Arkansas Nuclear
Issue date:	03/01/2016
From:	; NRC/OE
To:	;
	AMT / M.Dapas
References
	DPO-2015-001
	Download: ML16061A362 (46)
	v • d • e

DPO Case File for DPO-2015-001 The following pdf represents a collection of documents associated with the submittal and disposition of a differing professional opinion (DPO) from an NRC employee involving concerns about the significance determination of a Yellow finding issued to Arkansas Nuclear One Unit 1 on June 23, 2014.

Management Directive (MD) 10.159, The NRC Differing Professional Opinions Program, describes the DPO Program. http://www.internal.nrc.gov/policy/directives/toc/md10.159.htm The DPO Program is a formal process that allows employees and NRC contractors to have their differing views on established, mission-related issues considered by the highest level managers in their organizations, i.e., Office Directors and Regional Administrators. The process also provides managers with an independent, multi-person review of the issue (one person chosen by the employee). After a decision is issued to an employee, he or she may appeal the decision to the Executive Director for Operations (EDO).

Because the disposition of a DPO represents a multi-step process, readers should view the records as a collection. In other words, reading a document in isolation will not provide the correct context for how this issue was considered by the NRC.

The records in this collection have been reviewed and approved for public dissemination.

Document 1: DPO Submittal Document 2: Memo Establishing DPO Panel Document 3: DPO Panel Report Document 4: Comments from Submitter for RA to Consider Document 5: DPO Decision ADAMS ML16061A362

Document 1: DPO Submittal

Document 2: Memo Establishing DPO Panel September 23, 2015 MEMORANDUM TO: Michael C. Cheok, Panel Chairperson Office of New Reactors Russell A. Gibbs, Panel Member Office of Nuclear Reactor Regulation George T. MacDonald, Panel Member Region II Laura L. Kozak, Panel Member Region III THRU: Patricia K. Holahan, Director /RA/

Office of Enforcement FROM: Renée M. Pedersen /RA/

Sr. Differing Professional Views Program Manager Office of Enforcement

SUBJECT:

AD HOC REVIEW PANEL - DIFFERING PROFESSIONAL OPINION ON SIGNIFICANCE OF YELLOW FINDING AT ANO-1 (DPO-2015-001)

In accordance with Management Directive (MD) 10.159, The NRC Differing Professional Opinion Program; and in my capacity as the Differing Professional Opinion (DPO) Program Manager; and in coordination with Patricia Holahan, Director, Office of Enforcement; Marc Dapas, Regional Administrator, Region IV; and the DPO submitter; you are being appointed as members of a DPO Ad Hoc Review Panel (DPO Panel) to review a DPO submitted by a U.S.

Nuclear Regulatory Commission (NRC) employee. We have exercised discretion in accordance with the guidance in the MD and appointed four members to this panel due to the complexity of the issues.

The DPO (Enclosure 1) raises concerns about the significance determination of a Yellow finding issued to Arkansas Nuclear One Unit 1 on June 23, 2014. Because of the subject of the DPO, it has been forwarded to Mr. Dapas for consideration and issuance of a DPO Decision.

CONTACTS: Renée Pedersen, OE (301) 415-2742 Marge Sewell, OE (301) 415-8045

M. Cheok, et al. 2 The DPO Panel has a critical role in the success of the DPO Program. Your responsibilities for conducting the independent review and documenting your conclusions in a report are addressed in the handbook for MD 10.159 in Section II.F and Section II.G, respectively. The DPO Web site also includes helpful information, including interactive flow charts, frequently asked questions, and closed DPO cases, including previous DPO Panel reports. We will also be sending you additional information that should help you implement the DPO process.

Because this process is not routine, we will be meeting and communicating with all parties during the process to ensure that everyone understands the process, goals, and responsibilities. Disposition of this DPO should be considered an important and time sensitive activity. The timeliness goal for issuing a DPO Decision is 120 calendar days from the day the DPO is accepted for review. The timeliness goal for issuing this DPO Decision is January 4, 2016.

Process Milestones and Timeliness Goals for this DPO are included as Enclosure 2. The timeframes for completing process milestones are identified strictly as goalsa way of working towards reaching the DPO timeliness goal of 120 calendar days. The timeliness goal identified for your DPO task is 75 calendar days.

Although timeliness is an important DPO Program objective, the DPO Program also sets out to ensure that issues receive a thorough and independent review. The overall timeliness goal should be based on the significance and complexity of the issues and the priority of other agency work. Therefore, if you determine that your activity will exceed your 75-day timeliness goal, please send an e-mail to Mr. Dapas with a copy to DPOPM.Resource@nrc.gov and include the reason for the extension request and a proposed completion date for your work.

Mr. Dapas can then determine if he needs to submit an extension request for a new DPO timeliness goal to the Executive Director for Operations for approval.

An important aspect of our organizational culture includes maintaining an environment that encourages, supports, and respects differing views. As such, you should exercise discretion and treat this matter appropriately. Documents should be distributed on an as-needed basis. In an effort to preserve privacy, minimize the effect on the work unit, and keep the focus on the issues; you should simply refer to the employee as the DPO submitter. Avoid conversations that could be perceived as hallway talk on the issue and refrain from behaviors that could be perceived as retaliatory or chilling to the DPO submitter or that could potentially create a chilled environment for others. It is appropriate for employees to discuss the details of the DPO with their co-workers as part of the evaluation; however, as with other predecisional processes, employees should not discuss details of the DPO outside the agency. If you have observed inappropriate behaviors or receive outside inquiries or requests for information, please notify me.

On an administrative note, please ensure that all DPO-related activities are charged to Activity Code ZG0007.

We appreciate your willingness to serve and your dedication to completing an independent and objective review of this DPO. Successful resolution of the issues is important for NRC and its stakeholders. If you have any questions or concerns, please feel free to contact me or Marge.

M. Cheok, et al. 3 We look forward to receiving your independent review results and recommendations.

Enclosures:

1. DPO-2010-001

2. Process Milestones and Timeliness Goals cc: w/o

Enclosures:

M. Dapas, RIV K. Kennedy G. Replogle, RIV G. Holahan, NRO N. Sanfilippo, NRR A. Masters, RII A. Stone, RIII P. Holahan, OE M. Sewell, OE

M. Cheok, et al. 3 We look forward to receiving your independent review results and recommendations.

Enclosures:

1. DPO-2010-001

2. Process Milestones and Timeliness Goals cc: w/o Enclosures M. Dapas, RIV K. Kennedy G. Replogle, RIV G. Holahan, NRO N. Sanfilippo, NRR A. Masters, RII A. Stone, RIII P. Holahan, OE M. Sewell, OE ADAMS Package: ML15265A526 MEMO: ML15265A574 OE-011 OFFICE OE: DPO/PM OE: D NAME RPedersen PHolahan DATE 9/ 22/2015 9/23 /2015 OFFICIAL RECORD COPY

Document 3: DPO Panel Report January 22, 2016 MEMORANDUM TO: Marc L. Dapas, Regional Administrator Region IV FROM: Michael C. Cheok, Panel Chair /RA/

Russell A. Gibbs, Panel Member /RA/

George T. MacDonald, Panel Member /RA/

Laura L. Kozak, Panel Member /RA/

SUBJECT:

DIFFERING PROFESSIONAL OPINION PANEL REPORT ON THE SIGNIFICANCE DETERMINATION OF A YELLOW FINDING AT ANO UNIT 1 (DPO-2015-001)

In a memorandum dated September 23, 2015, we were appointed as members of a Differing Professional Opinion (DPO) Ad Hoc Review Panel (Panel) to review a DPO regarding the significance determination of a Yellow finding issued to Arkansas Nuclear One (ANO) Unit 1 on June 23, 2014. The Panel reviewed the DPO in accordance with Management Directive 10.159, NRC Differing Professional Opinion Program. The Panels report is enclosed for your consideration in issuing a DPO Decision.

The Panel concluded that the ANO Unit 1 event was a very complex event which required a detailed risk analysis to determine the best estimate results for the significance determination.

The Panel therefore concluded that the staffs process used to determine the Yellow finding issued to ANO Unit 1 on June 23, 2014 was the appropriate process to use. The Panel concluded that the Risk Assessment Standardization Project (RASP) Handbook is a risk assessment guidance (or methods) document for capturing best practices for performing risk evaluations, as such, the Panel considers that flexibility in the use of the RASP Handbook is essential as long as its application is not inconsistent with program requirements. Finally, the Panel concluded that the agencys proposed response to DPO-2014-002 (ADAMS Accession Number ML14344A291) for establishing a more rigorous process for review and approval for changes to the RASP Handbook to be adequate.

Although the Panel concluded that the correct processes were used for the ROP evaluation for the ANO Unit 1 stator drop event, the Panel identified several potential process improvements for your consideration. We appreciate that these recommendations involve areas that are outside of your responsibility. Therefore we are providing a copy of this memorandum to Bill Dean, the Director of the Office of Nuclear Reactor Regulation, who has responsibility for these activities.

The Panel recommends that a comprehensive review of the RASP Handbook be performed to ensure its guidance is not inconsistent with program requirements.

The DPO Panel recommends that the purpose and use of the RASP Handbook be clarified to ensure it remains a living methods document which takes into account the

use of available best practices which may or may not be specified in higher tier program documents.

The Panel recommends that the comprehensive review of the RASP handbook include additional guidance on a safe, stable, end state and appropriate consideration of the need to increase the mission time of modeled components.

The panel recommends that Inspection Manual Chapters 0609 and 0308 be revised to clarify the expected need for flexibility in performing Significance Determination Process (SDP) evaluations. While the panel determined the documents already allow flexibility, additional clarity would be helpful in order to ensure appropriate technical assumptions are developed consistent with the unique aspects of individual findings.

The Panel recommends that the initiative to further develop the RASP handbook quality assurance process beyond that recommended by the response provided by DPO-2014-002 be carefully considered taking into account agency resources and long term value added.

Please do not hesitate to contact us if you have any questions regarding the enclosed report.

Enclosure:

DPO Panel Report cc: G. Replogle, RIV P. Holahan, Director, OE R. Pedersen, DPOPM W. Dean, Director, NRR

use of available best practices which may or may not be specified in higher tier program documents.

The Panel recommends that the comprehensive review of the RASP handbook include additional guidance on a safe, stable, end state and appropriate consideration of the need to increase the mission time of modeled components.

The panel recommends that Inspection Manual Chapters 0609 and 0308 be revised to clarify the expected need for flexibility in performing Significance Determination Process (SDP) evaluations. While the panel determined the documents already allow flexibility, additional clarity would be helpful in order to ensure appropriate technical assumptions are developed consistent with the unique aspects of individual findings.

The Panel recommends that the initiative to further develop the RASP handbook quality assurance process beyond that recommended by the response provided by DPO-2014-002 be carefully considered taking into account agency resources and long term value added.

Please do not hesitate to contact us if you have any questions regarding the enclosed report.

Enclosure:

DPO Panel Report cc: G. Replogle, RIV P. Holahan, Director, OE R. Pedersen, DPOPM W. Dean, Director, NRR Non-public ADAMS Package Accession No.: ML16021A233 ADAMS Memo Accession No.: ML16021A185 OE-011 OFFICE DPO/PC DPO/PM DPO/PM DPO/PM NAME MCheok RGibbs GMacDonald LKozak DATE 1/ 19 /2016 1/ 19 /2016 1/ 13 /2016 1/ 14 /2016 OFFICIAL RECORD COPY

Differing Professional Opinion (DPO) on the Significance Determination of a Yellow Finding at ANO Unit 1 (DPO-2015-001)

DPO Panel Report

/RA/

Michael C. Cheok, Panel Chair

/RA/

Russell A. Gibbs, Panel Member

/RA/

George T. MacDonald, Panel Member

/RA/

Laura L. Kozak, Panel Member Date: January 22, 2016 ENCLOSURE

Introduction Differing Professional Opinion (DPO-2015-001) was received on September 2, 2015. The concerns in the DPO involved the NRCs Significance Determination Process (SDP) evaluation of the March 2013 stator drop event at Arkansas Nuclear One Unit 1 (ANO Unit1).

The NRC determined the finding for ANO Unit 1 to be Yellow, a finding of substantial safety significance. The final significance determination letter was issued on June 23, 2014.

The memorandum from the Senior Differing Professional Views Program Manager, Office of Enforcement, establishing the Differing Professional Opinion Panel (DPO Panel or Panel) was issued on September 23, 2015. The memorandum tasked the Panel with conducting an independent review of the issues in accordance with Management Directive (MD) 10.159, NRC Differing Professional Opinion Program.

The Panel met with the submitter on October 6, 2015, and established a concise statement of the submitters concerns (see below). The submitter approved the statement of concerns on October 15, 2015. During the course of the Panels review, the Panel interviewed the DPO submitter on several occasions, conducted numerous NRC document reviews, and interviewed managers and members of the staff from the Office of Nuclear Reactor Regulation (NRR), Region IV, and the other regional offices.

Statement of Concerns Based on a review of the DPO submittal and associated references, and an interview with the submitter, the following concerns were identified by the Panel:

1. The staff is not following certain procedures associated with determining the significance of inspection findings. Inspection Manual Chapters (IMCs) 0308 and IMC 0609 are the governing documents for Significance Determination Project (SDP) risk determinations and the Risk Assessment Standardization Project (RASP) Handbook is a sub-tier document. Program requirements in IMCs 0308 and 0609 must be followed when there is a conflict between these documents and the RASP Handbook. The Phase 2 process documented in IMC 0609 Appendix G should have been used for the ANO Unit 1 stator drop SDP evaluation. Instead, guidance from the RASP Handbook was used. The RASP Handbook is not consistent with the program requirements specified in IMCs 0308 and 0609 or with the ASME PRA Standards document. (The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months vs. 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months diesel generator mission time (6 day total mission time) was the example used to highlight this issue.)

2. If the process identified in IMC 0609 Appendix G had been used, the SDP finding for the ANO Unit 1 stator drop should be Green. Instead, because of the above two issues, the SDP finding was finalized as Yellow. (If the finding is Green, the resulting NRC inspections at ANO Unit 1 should be based on Inspection Procedure (IP) 95002 instead of IP 95003.)

3. (a) The RASP Handbook contains several pieces of inaccurate information and the review and approval process for the handbook is not rigorous. (b) The current RASP Handbook change process is inadequate.

Evaluation of Concerns Concern 1 Concern 1, as articulated in the Statement of Concerns, is as follows:

The staff is not following certain procedures associated with determining the significance of inspection findings. IMC 0308 and IMC 0609 are the governing documents for SDP risk determinations and the RASP Handbook is a sub-tier document. Program requirements in IMCs 0308 and 0609 must be followed when there is a conflict between these documents and the RASP Handbook.

The Phase 2 process documented in IMC 0609 Appendix G should have been used for the ANO Unit 1 stator drop SDP evaluation. Instead, guidance from the RASP handbook was used.

The RASP Handbook is not consistent with the program requirements specified in IMCs 0308 and 0609 or with the ASME PRA standards document. (The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months vs.

72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months diesel mission time (6 day total mission time) was the example used to highlight this issue.

Background - Summary of ANO Unit 1 stator drop SDP evaluation During a refueling outage on March 31, 2013, a temporary overhead crane being used to move the generator stator from Unit 1 collapsed. Unit 1 lost electrical power from offsite sources due to damage caused by the dropped stator. Offsite power was not restored for 6 days.

On April 1, 2013, a risk evaluation of the event was performed in accordance with MD8.3, NRC Incident Investigation Program to evaluate the level of NRC response for the event. At the time, Unit 1 was in the refueling mode with the reactor cavity flooded. A Region IV SRA used IMC 0609 Appendix G, Attachment 2, Phase 2 Significance Determination Process Template for PWR during shutdown, along with other risk evaluation tools and analyst judgment to estimate the conditional core damage probability (CCDP) of the event. The evaluation was reviewed by a risk analyst in NRR/DRA who specializes in shutdown risk assessment. The estimated CCDP for Unit 1 was 1.6E-4, which along with the assessment of the deterministic criteria in MD8.3, met the threshold for performing a reactive inspection with an Augmented Inspection Team (AIT). The MD8.3 evaluation documented several unknown aspects of the event that could affect (increase) the risk estimate.

The AIT report was issued on June 7, 2013. The report discussed 10 unresolved items that were under NRC review. From July 15, 2013 through February 2, 2014, RIV conducted an AIT follow-up inspection to review the unresolved items and develop any inspection findings.

During this period a potential finding and violation for Unit 1 was identified. The finding was evaluated using phase 1 of IMC 0609 Appendix G, Shutdown Operations SDP. Specifically, the inspectors used IMC 0609 Appendix G Attachment 1 Checklist 4 and determined that the finding required a phase 2 or 3 analysis because it was a finding that degraded the licensees ability to add reactor coolant system inventory when needed since a loss of offsite power occurred.

A phase 2 significance determination evaluation was not performed. A detailed risk evaluation, also known as a phase 3 evaluation, was performed by NRR/DRA. One of the assumptions in the detailed risk evaluation was a mission time of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months for the emergency diesel generators and a mission time of 6 days for offsite power recovery. The inspection report stated the assumption as follows:

PRA mission time is normally assumed to be 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . However, after the event was initiated it took approximately six days to recover offsite power. If the emergency diesel generators failed after running successfully for three days the time to core uncovery was over three days after the loss of DHR (Decay Heat Removal). Thus the emergency diesel generator mission time was modified to 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months .

The detailed risk evaluation was peer reviewed by the RIV SRA who performed the initial MD8.3 risk evaluation and by another risk analyst in NRR/DRA. On January 30, 2014, a Significance and Enforcement Review Panel (SERP) was held to discuss the significance of the findings. The SERP agreed to issue a preliminary Red finding for Unit 1.

At a regulatory conference held on May 1, 2014 to discuss the significance of the findings, the licensee presented information to the NRC on potential recovery actions that could have been implemented to establish and maintain cooling if needed and requested that the NRC consider the recovery actions in the final SDP evaluation. NRC risk analysts considered the licensees proposed recovery actions and revised the detailed risk evaluation. Additional SERP meetings were held on May 27, 2014 and May 29, 2014, to discuss the revised evaluation and the significance of the findings. The SERP concluded the finding for Unit 1 should be finalized as Yellow, a finding of substantial safety significance. The final significance determination letter was issued on June 23, 2014. The licensee did not appeal the final significance determination.

Evaluation:

The panel noted that the staff did not use the IMC 0308 and IMC 0609 Appendix G guidance that would have screened the finding to green as stated in the DPO. However as discussed below, the panel found that the staff appropriately deviated from this specific guidance when they determined that the finding would not be adequately assessed for significance given the inherent assumption of a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time in Appendix G.

Appendix G provides guidance for phase 1 and 2 significance determinations for shutdown findings in various shutdown modes of operation. For the refueling mode of operation with the reactor cavity flooded, commonly referred to as plant operating state (POS) 3, the safety significance of findings would typically be very low (Green) because the amount of water above the reactor core allows for significant time to recover the decay heat removal function if it was not available. Specifically, for such scenarios, the time to core damage would be greater than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . Since the Appendix G guidance uses an inherent assumption of a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time for successful mitigation of core damage (which is widely used in probabilistic risk assessment (PRA)), the guidance will lead to a Green outcome.

During interviews, the staff involved with the detailed risk evaluation informed panel members they recognized that guidance in Appendix G would screen the finding to Green but determined that this was not appropriate based on event-specific information and on the previous staff risk evaluation in support of the MD8.3 decision. When the finding was

identified during the AIT follow-up inspection and it was determined to be related to the cause of the initiating event, the RIV SRA determined that, similar to the MD8.3 evaluation, a deviation from the existing Appendix G guidance that used the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time assumption would be necessary. The licensee performance deficiency directly led to the stator drop hence the phase 2 risk estimate completed for the MD8.3 evaluation, had it been done again for SDP purposes, would have been essentially unchanged. As a result, no phase 2 was performed and NRR was requested to perform a detailed risk evaluation. The detailed risk analysis simply stated that no phase 2 evaluation was performed but did not specifically document the reasons why Appendix G phase 2 could not adequately address this finding.

However, the detailed risk evaluation appropriately documented the assumptions that were used to evaluate the finding.

The need to deviate from IMC 0308 and IMC 0609 appendices to perform a detailed risk evaluation of a finding is recognized by the inspection manual. The panel noted the following relevant statements as a few examples that describe a general philosophy in the significance determination process that an analyst may deviate from phase 1 or phase 2 guidance, if necessary.

IMC 0308 Attachment 3, Significance Determination Process Basis Document, section C.3.5 stated:

Phase 2 for any risk-informed SDP should, as much as possible, provide a simplified risk-informed process that can be implemented by inspectors and be used as a risk communication tool. The public basis for an SDP results does not have to be more extensive or resource intensive than Phase 2 if this basis reflects the staffs basic understanding of the significance, which may be checked by professional risk-analysts using more detailed computer-based risk models. Even when the reactor safety SDP tool (phase 2) cannot be used for a particular reactor safety inspection finding because its pre-specified imbedded assumptions are not appropriate to the finding, the departure from the publically documented process (i.e., a phase 3 analysis) can often be understood in terms of appropriate adjustments that are made to the phase 2 model. Thus the published SDP model may continue to serve a valuable role as a communication tool, even for phase 3 analysis.

Phase 3 was defined to address the expected need to depart from the Phase 2 guidance when the Phase 2 modeling assumptions are known to be inaccurate or incomplete, and requires professional risk analysts to be involved in all such cases.

IMC 0308 Attachment 3, Appendix A, section 3.1, The Technical Basis for the At-Power Screening Questions also provides guidance that the staff can deviate from the existing guidance if necessary. The following excerpt expresses this point:

Therefore, as a conservative measure, if a finding screens to green in accordance with the applicable screening questions and the staff has reason to believe that there is still potential that the finding is risk significant, the staff reserves the opportunity to perform a more detailed risk evaluation.

IMC 0609 Appendix G guidance also recognizes that a quantitative evaluation can be a phase 2 or a phase 3, both are not required, and that certain complex findings need to go directly to a detailed risk evaluation performed by headquarters staff. Appendix G also states

that the SRA determines which findings require a detailed risk evaluation. Below are several relevant excerpts from the version of Appendix G in effect at the time this SDP was in progress on this point:

IMC 0609 Appendix G, section 3.2, Objective, stated:

When using this guidance to assess a finding, there are two possible outcomes:

(1) the finding requires quantitative assessment (Phase 2 or Phase 3 analysis) to determine its risk significance, or (2) the finding can be screened as having very low risk significance (Green).

Further it stated:

Caution: To determine if a shutdown finding needs quantitative assessment, the inspector should review Appendix G, Attachment 1 to ensure that the licensee is maintaining an adequate mitigation capability and (2) Table 1 if an event occurred that could be characterized as a loss of control. If these conditions occur, the finding needs to be quantitatively assessed.

Further NRC IMC 0609 Appendix G, Section 3.5 stated:

If a finding needs quantitative assessment, then the finding should be forwarded to the SRA. The SRA will then decide if the finding should be forwarded to NRR for Phase 3 analysis or the finding will be evaluated using the Phase 2 PWR and BWR templates located in Attachments 2 and 3 respectively. The SRA should be sent the completed checklists associated with the finding and a complete description of the finding.

After interviewing staff involved in the analysis of the finding and reviewing documents, the panel concluded that this was a very complex event which should not have screened to green as the NRCs best estimate for the significance determination. This event was an extended loss of offsite power (LOOP) with many complications that occurred during a time when the electrical distribution systems were not in the normal alignment. This level of complexity would necessitate a detailed risk evaluation. The panel found that the Inspection Manual guidance recognizes that these complex issues can occur and allows the NRC to perform a detailed risk evaluation as necessary.

The panel also determined that the Appendix G guidance for phase 1 and 2 that would screen most findings using a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time assumption is generally applicable. However, in this specific case, the fact that offsite power was not recovered for six days caused this event and related finding to be outside the inherent assumptions of the IMC 0609 Appendix G PWR template for findings in POS 3.

Given the determination that the existing guidance was not applicable for this specific finding, the NRR risk analyst developed an alternate input regarding mission time. All inputs and assumptions and a list of generic references were documented in the SERP worksheet and in the inspection report. The analyst used a 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months mission time for the emergency diesel generators rather than the typically used 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time assumed in the IMC 0308 and IMC 0609 guidance. The panel discussed this particular assumption with the analyst and determined that it was appropriately developed based on the event that occurred.

The RASP manual provides methods and guidance to perform risk evaluations. It contains a section on mission time that provides guidance for risk analysts. It states that it is not within the scope of the manual to repeat program-specific requirements and if there is a conflict between RASP and the IMCs that the program specific requirements supersede the RASP manual guidance. The panel did not view the general use of a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time for phase 2 of Appendix G as a program requirement and instead considered the use of a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time as an assumption of the SDP that is generally appropriate but not required to be used in an SDP evaluation, if it is not appropriate to the finding. Therefore, the panel did not see a conflict between Appendix G and the RASP manual for the example provided.

The detailed risk evaluation, including the assumption to use a mission time greater than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , was peer reviewed by other risk analysts, reviewed by the SERP panel, and also provided to the licensee for their review. None of these reviews challenged the mission time assumption. The panel considered this fact as further evidence that deviating from Appendix G and using an increased mission time was reasonable for this inspection finding.

With respect to the RASP manual consistency with the ASME/ANS PRA Standard (PRA standard) document regarding mission time, the panel reviewed the manual and the standard.

The RASP manual is an NRC document and was written primarily for evaluating the safety significance of events and findings for the Reactor Oversight Process and the Accident Sequence Precursor Program. In these cases, event-specific input is important. The PRA standard is used to guide the development of baseline probabilistic risk assessments to estimate the overall risk from typical (or best estimate) plant operations. Since the documents are references for different uses, it would not be unexpected that there would be some differences in the way analysis input or assumptions are applied. The panel did not see any substantive differences with respect to mission time guidance. The DPO submitter questioned the meaning of some terms used, notably the term safe, stable, state. The panel agreed that this term, which is used in the PRA standard, could be further explained in the RASP manual to help risk analysts recognize situations where alternate assumptions regarding mission time or functional success criteria should be considered.

==

Conclusions:==

The panel noted that the staff did not use the IMC 0308 and IMC 0609 Appendix G guidance for the SDP evaluation for the ANO Unit 1 stator drop event. However, the Panel concluded that the staff appropriately deviated from this specific guidance when they determined that the finding would not be adequately assessed for significance given the inherent assumption of a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time in Appendix G.

The panel concluded that the ANO Unit 1 stator drop event was a very complex event which would require a detailed risk evaluation for the SDP determination. This event was an extended LOOP with many complications that occurred during a time when the electrical distribution systems were not in the normal alignment. The panel found that the Inspection Manual guidance recognizes that these complex issues can occur and allows the NRC to perform a detailed risk evaluation as necessary.

The panel also determined that the IMC 0609 Appendix G guidance for phase 1 and 2 that would screen most findings using a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time assumption is generally applicable. In this specific case, the fact that offsite power was not recovered for six days caused this event and related finding to be outside the inherent assumptions of the IMC 0609 Appendix G PWR template for findings in POS 3.

Recommendations:

The panel recommends that the comprehensive review of the RASP handbook include additional guidance on a safe, stable, end state and appropriate consideration of the need to increase the mission time or other analysis assumptions or functional success criteria of modeled components.

The panel recommends that the IMC 0609 and IMC 0308 documents be revised to clarify the expected need for flexibility in performing SDP evaluations. While the panel determined the documents already allow flexibility, in order to ensure appropriate technical assumptions are developed consistent with the unique aspects of individual findings, additional clarity would be helpful.

Concern 2: If the process identified in IMC 0609 Appendix G had been used, the SDP finding for the ANO Unit 1 stator drop should be Green.

The Panel reviewed the ANO Unit 1 stator drop event and determined that, if IMC 0609 Appendix G had been used, the SDP finding would be Green. However, as discussed in the write-up for Concern 1, the Panel is of the opinion that the ANO Unit 1 stator drop event was a complicated event with several unique circumstances. As such, the evaluation of safety significance for the event required input and assumptions that are more event-specific and thus warranted a more detailed risk analysis. The Panel finds that the more detailed risk analysis process used by NRC staff to arrive at a Yellow finding was the appropriate one to use. (Note that the Panels review focused on the processes used and on the inputs to these processes. The Panel did not focus on the details of the evaluations or their results.)

==

Conclusions:==

The evaluation of safety significance for the ANO Unit 1 stator drop event required a more detailed risk evaluation, and the staffs process used to arrive at a Yellow finding for the ANO Unit 1 stator drop event was the appropriate one to use.

Recommendations:

None.

Concern 3(a) -The RASP Handbook contains several pieces of inaccurate information.

The Panel interviewed the DPO submitter and various agency staff and management to better understand the purpose and intent of the RASP Handbook. Consistent with the guidance in the handbook, its purpose and intent is to provide a means for risk analysts to use standard and consistent approaches and best practices in performing risk applications that are not inconsistent with implementing requirements. The RASP Handbook states the following:

Relationships to program requirements. This handbook is intended to provide guidance for implementing requirements contained in program-specific procedures, such as Inspection Manual Chapter (IMC) 0609, Significance Determination Process, MD 8.3, IMC 0308, Reactor Oversight Process (ROP) Basis Document, and IMC 0309, Reactive Inspection Decision Basis for Reactors. It is not the scope of this handbook to repeat program-specific requirements in the handbook, since these requirements may differ among applications and

may change as programs evolve. Program-specific requirements supersede guidance in this handbook.

The Panel notes that there may be possible misinterpretation on what the handbook represents in terms of guidance. Some are of the opinion that the handbook is meant as a procedure to be followed as written with the handbook to be fully consistent with program requirements. Others believe that the handbook (while remaining consistent with program requirements) should be considered a living document subject to change as experience is obtained in its use and that the handbook may offer guidance that is not necessarily contained in other documents. There is a general consensus among the staff and managers interviewed that when a particular approach is used, deviations may be allowed as long as these are approved and sufficiently justified and documented in the analysis.

All parties interviewed agreed that the RASP Handbook is a methods document that captures best practices for performing the various risk assessments and is expected to evolve with use. These best practices are oftentimes not specifically addressed in specific program requirements such as those mentioned above. As such, there may be situations where the analyst, using his or her experience and knowledge, uses the RASP Handbook to apply risk assessment approaches, with the possibility that the approach itself may not have been used before. However, in all circumstances the risk analyst is obligated to ensure that any given approach identified is not inconsistent with program requirements. The term inconsistent (versus consistent) is used because the program requirements may be silent on the appropriate risk evaluation method chosen for the assessment. The DPO Panel agrees that the RASP Handbook should retain its flexibility in this manner. The Panel agrees that it is not a requirements document. Rather, it is a collection of acceptable approaches to performing risk assessments.

In applying this flexibility, there may arise situations where approaches identified in the RASP Handbook do not clearly coincide with program requirements. In these situations, the analyst is obligated to consult with and to inform the technical and program experts, managers and other involved staff pertinent to the assessment outcome to ensure that the intent of program requirements are satisfied. It is also expected that these situations are identified for follow-up to provide the necessary clarity for subsequent assessments.

==

Conclusions:==

The DPO Panel did not identify that the RASP Handbook contained several pieces of inaccurate information. The panel, however, believes a more appropriate expression for concern would be on the consistency of handbook contents when compared with program requirements. The panel concluded that the handbook would benefit from a comprehensive review to ensure its guidance is not inconsistent with existing program requirements.

The DPO Panel does not consider the RASP Handbook as a requirements document.

Rather, it represents risk assessment guidance that is a methods document for capturing best practices for performing risk evaluations.

The DPO Panel considers that flexibility in the use of the RASP Handbook is essential as long as its application is not inconsistent with program requirements. This approach is considered by the DPO Panel in the best interest of furthering the application of risk technology.

Recommendations:

The DPO Panel recommends that a comprehensive review of the RASP Handbook be performed to ensure its guidance is not inconsistent with program requirements.

The DPO Panel recommends that the purpose and use of the RASP Handbook be clarified to ensure it remains a living methods document which takes into account the use of available best practices which may or may not be specified in higher tier program documents.

Concern 3(b) - The review and approval process for the handbook is not rigorous. The current RASP Handbook change process is inadequate.

The DPO Panel interviewed the DPO Submitter and staff and management in NRRs Division of Risk Assessment to gain a better understanding of the identified statement of issue. The panel also reviewed the Agency response to DPO-2014-002 (ML14344A291).

The DPO Panel independently assessed the agency actions relative to the review and approval process established as a result of DPO-2014-002 and concluded that the actions were adequate and represented a considerable improvement over the previous process.

However, the panel noted that the review and approval process had not been incorporated into the RASP Handbook at the time of the panels review due to other competing priorities as expressed by the responsible Branch Chief.

The panel noted that an even more rigorous review and approval process for the RASP Handbook was under development. The project consisted of two phases. The first phase is to establish reasonable quality assurance requirements for the RASP Handbook. The second phase involves identifying discrepancies between the RASP Handbook and the program requirements.

For the first phase of the project, the DPO panel reviewed draft material being developed for that process and considered the material to be of very high quality but questioned the need for such an intensive process - a process that appears to go well beyond agency established practices for document development and revision as described in IMC 0040, Preparing, Revising and Issuing Documents for the NRC Inspection Manual. The panel viewed the draft process as potentially very resource intensive. The added value of such a review may not be commensurate with the resources required, particularly because the use of the RASP manual guidance is typically reviewed by staff and management during SDP, accident sequence precursor (ASP), Notice of Enforcement Discretion (NOED), and MD8.3 event response evaluations.

For the second phase of the project, the DPO Panel, after discussions with relevant staff and management, agree that a comprehensive review of the RASP Handbook against implementing requirements is warranted. The DPO Panel discussed the suggestion to perform the comprehensive review with DRA management who agreed that the review was needed.

Conclusions:

The DPO Panel considers the agencys proposed response to DPO-2014-002 for establishing a more rigorous process for review and approval for changes to the RAS Handbook to be adequate.

The DPO Panel agrees that a comprehensive review of the RASP Handbook against implementing requirements is warranted.

Recommendation:

The DPO Panel recommends that the initiative to further develop the RASP handbook quality assurance process beyond that recommended by the response provided by DPO-2014-002 be carefully considered taking into account agency resources and long term value added.

Overall Conclusions Regarding DPO-2015-001 The Panel concludes that the ANO Unit 1 event was a very complex event which required a more detailed analysis to be used to determine the best estimate results for the significance determination. The panel found that the Inspection Manual guidance recognizes that these complex issues can occur and allows the NRC to perform a detailed risk evaluation as necessary.

The Panel determined that the IMC 0609 Appendix G guidance for phase 1 and 2 evaluations that would screen most findings using a 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months mission time assumption to be generally applicable. However, this guidance would not be appropriate for events where the mission time is appreciably greater or less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months (for example, in the ANO Unit 1 stator drop event, offsite power was not recovered for six days).

The Panel concludes that the process used to arrive at a Yellow SDP finding for the ANO Unit 1 stator drop event was the appropriate one to use.

The Panel concludes that the RASP Handbook represents risk assessment guidance that is meant to be a methods document for capturing best practices for performing risk evaluations. The Panel considers that flexibility in the use of the RASP Handbook is essential as long as its application is not inconsistent with program requirements. Although the Panel did not agree that the RASP Handbook necessarily contained several pieces of inaccurate information, the Panel concluded that the handbook would benefit from a comprehensive review to ensure its guidance was not inconsistent with existing program requirements.

The Panel concludes that the agencys proposed response to DPO-2014-002 for establishing a more rigorous process for review and approval for changes to the RASP Handbook to be adequate.

11 Overall Recommendations Regarding DPO-2015-001 Based on the Panels review, the following recommendations are provided for consideration by the Office of Nuclear Reactor Regulation:

The Panel recommends that a comprehensive review of the RASP Handbook be performed to ensure its guidance is not inconsistent with program requirements.

The DPO Panel recommends that the purpose and use of the RASP Handbook be clarified to ensure it remains a living methods document which takes into account the use of available best practices which may or may not be specified in higher tier program documents.

The Panel recommends that the comprehensive review of the RASP handbook include additional guidance on a safe, stable, end state and appropriate consideration of the need to increase the mission time of modeled components.

The panel recommends that IMC 0609 and IMC 0308 documents be revised to clarify the expected need for flexibility in performing SDP evaluations. While the panel determined the documents already allow flexibility, additional clarity would be helpful in order to ensure appropriate technical assumptions are developed consistent with the unique aspects of individual findings.

The Panel recommends that the initiative to further develop the RASP handbook quality assurance process beyond that recommended by the response provided by DPO-2014-002 be carefully considered taking into account agency resources and long term value added.

Document 4: Comments from Submitter for Regional Administrator to Consider

Document 5: DPO Decision Hi Marc, Thank you for forwarding the DPO Panel's report. I am very appreciative. I would like to provide just a few comments and then (because of my current situation) I'll be done. I don't believe that I'll be employed by the NRC much longer, so I'll have to forfeit my appeal rights.

One of the conclusions was that the NRC followed the required process. I could not disagree with this conclusion more. While the process does allow analysts to perform a Phase 3 at any time, it's also important to document the deviation from the process and justify the reason(s). This was not performed. It also does not permit unreasonable assumptions (like extending the accident mission time to six days just to obtain core damage).

The RASP Handbook is a methods book and does not represent program requirements. In fact, Volume 4, specifically states:

1.2 The scope of the handbook is provided below. ..

Relationships to Program Requirements. This handbook is intended to provide guidance for implementing requirements contained in program-specific procedures, such as Inspection Manual Chapter (IMC) 0609, Significance Determination Process, and IMC 0309, Reactive Inspection Decision Basis for Reactors. It is not the scope of this handbook to repeat program-specific requirements in the handbook, since these requirements may differ among applications and may change as programs evolve. Program-specific requirements supersede guidance in this handbook.

Again, thanks for the opportunity to review the report.

George

UNITED STATES NUCLEAR REGULATORY COMMISSION REGION IV 1600 E. LAMAR BLVD.

ARLINGTON, TX 76011-4511 February 2, 2016 MEMORANDUM TO: George D. Replogle, Senior Reactor Analyst Division of Reactor Safety, Region IV FROM: Marc L. Dapas, Regional Administrator, Region IV /RA/

SUBJECT:

DIFFERING PROFESSIONAL OPINION REGARDING THE SIGNIFICANCE DETERMINATION PROCESS EVALUATION FOR A FINDING AT ARKANSAS NUCLEAR ONE INVOLVING THE MARCH 2013, UNIT 1 STATOR DROP EVENT (DPO-2015-001)

On September 2, 2015, in accordance with Management Directive 10.159, The Differing Professional Opinions Program, you submitted a differing professional opinion (DPO) concerning the significance determination process (SDP) evaluation result of Yellow for a finding at Arkansas Nuclear One (ANO) involving a Unit 1 stator drop event that occurred in March 2013. Upon coordination with Patricia Holahan, Director, Office of Enforcement (OE),

myself (as the DPO decision authority), and you (as the DPO submitter), a DPO Ad Hoc Review Panel (the Panel) was established by memorandum from Renee Pedersen, Senior Differing Professional Views Program Manager, OE, dated September 23, 2015. The Panel was tasked with reviewing your DPO submittal and providing me with a report documenting the Panels conclusions and any associated recommendations. The Panel met with you on October 6, 2015, and based collectively on the results of that interview and review of the DPO submittal, developed a concise statement of your concerns. You approved the statement of concerns on October 15, 2015. Upon completing its deliberations, which included interviews with you on several occasions, completion of a number of document reviews, and interviews with staff and managers from the Office of Nuclear Reactor Regulation (NRR) and the regional offices, the Panel provided me with its report, dated January 22, 2016, for my consideration in issuing a decision regarding the subject DPO. A copy of the report was provided to you and you sent me an email response on January 28, 2016.

In order to make a decision with regard to your DPO, I reviewed your DPO submittal, the Panels report, and your January 28, 2016 email to me providing comments on the conclusions documented in the DPO Panels report, as well as the decision with respect to DPO-2014-002, Differing Professional Opinion Involving Use of Conditional Core Damage Probability to Evaluate Performance Deficiencies that Cause Initiating Events (ADAMS Accession Number ML14344A291), since that DPO decision was referenced in both the Panels report and your own submittal pertaining to this DPO (DPO-2015-001).

G. Replogle Statement of Concerns (1) The staff is not following certain procedures associated with determining the significance of inspection findings. Inspection Manual Chapter (IMC) 0308, Reactor Oversight Process (ROP) Basis Document, and IMC 0609, Significance Determination Process, are the governing documents for significance determination process (SDP) risk evaluations and the Risk Assessment Standardization Project (RASP) Handbook is a sub-tier document. Program requirements in IMCs 0308 and 0609 must be followed when there is a conflict between these documents and the RASP Handbook. The Phase 2 process documented in IMC 0609, Appendix G, Shutdown Operations Significance Determination Process, should have been used for the ANO Unit 1 stator drop SDP evaluation. Instead, guidance from the RASP Handbook was used. The RASP Handbook is not consistent with the program requirements specified in IMCs 0308 and 0609 or with the American Society of Mechanical Engineers (ASME) Probabilistic Risk Assessment (PRA) Standards document. (The 24-hour vs. 72-hour diesel generator mission time (6-day total mission time) was the example used to highlight this issue.)

(2) If the process identified in IMC 0609 Appendix G had been used, the SDP finding for the ANO Unit 1 stator drop should be Green. Instead, because of the above two issues, the SDP finding was finalized as Yellow. (If the finding is Green, the resulting NRC inspections at ANO Unit 1 should be based on Inspection Procedure (IP) 95002, Supplemental Inspection for One Degraded Cornerstone or Any Three White Inputs in a Strategic Performance Area, instead of IP 95003, Supplemental Inspection for Repetitive Degraded Cornerstones, Multiple Degraded Cornerstones, Multiple Yellow Inputs, or One Red Input.)

(3) The RASP Handbook contains several pieces of inaccurate information and the review and approval process for the handbook is not rigorous. In addition, the RASP Handbook change process is inadequate.

DPO Panel Conclusions (1) The ANO Unit 1 stator drop event was a very complex event which required a detailed risk analysis to determine the best estimate results for the significance determination.

(2) The process used by the staff to determine the significance of the associated performance deficiency, which resulted in the issuance of a Yellow finding to Entergy (the licensee for ANO) on June 23, 2014, was the appropriate process to use.

(3) The RASP Handbook is a risk assessment guidance (or methods) document for capturing best practices for performing risk evaluations, and as such, the flexibility in the

G. Replogle use of the RASP Handbook is essential as long as its application is not inconsistent with program requirements.

(4) The agencys response to DPO-2014-002, proposing the establishment of a more rigorous process for review and approval of proposed changes to the RASP Handbook, is adequate.

DPO Panel Recommendations Based on its conclusions and several potential process improvements identified during its review, the Panel made the following recommendations:

(1) A comprehensive review of the RASP Handbook be performed to ensure its guidance is not inconsistent with program requirements.

(2) The purpose and use of the RASP Handbook be clarified to ensure it remains a living methods document which takes into account the use of available best practices which may or may not be specified in higher tier program documents.

(3) The comprehensive review of the RASP handbook include additional guidance on a safe, stable, end state and appropriate consideration of the need to increase the mission time of modeled components.

(4) IMCs 0308 and 0609 be revised to clarify the expected need for flexibility in performing SDP evaluations.1 (5) The initiative to further develop the RASP handbook quality assurance process beyond that recommended by the response provided to DPO-2014-002, be carefully considered taking into account agency resources and long term value added.

Decision and supporting rationale After considering all of the information, I agree with the Panels conclusions and endorse the recommendations provided by the Panel for NRRs consideration. The basis for my decision follows.

Your principal concern that the staff did not follow the governing procedures associated with determining the significance of inspection findings, and as a result, reached the wrong SDP outcome of Yellow instead of Green for the finding pertaining to the ANO Unit 1 stator drop event, derives from the staffs use of a 72-hour mission time for the emergency diesel generators (EDGs) versus a 24-hour mission time as specified in IMC 0609, Appendix G, and 1 While the panel determined the documents already allow flexibility, additional clarity would be helpful in order to ensure appropriate technical assumptions are developed consistent with the unique aspects of individual findings.

G. Replogle its associated attachments, and IMC 0308, Attachment 3, Appendix G, BWR [Boiling Water Reactor] and PWR [Pressurized Water Reactor] Phase 2 Significance Determination Process for Shutdown. As you stated in your DPO submittal, use of IMCs 0609 and 0308 would have resulted in the subject finding screening to Green.

As noted in the Panel report, for the refueling mode of operation with the reactor cavity flooded, commonly referred to as plant operating state (POS) 3, the safety significance of findings would typically be very low (Green) because the amount of water above the reactor core allows for significant time to recover the decay heat removal (DHR) function if it was not available. Specifically, for such scenarios, the time to core damage would be greater than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . In performing Phase 1 and Phase 2 SDP evaluations for findings involving shutdown modes of operation, application of the IMC 0609 and IMC 0308 Appendix G guidance, which assumes a 24-hour mission time for successful mitigation of core damage, results in a Green finding.

The staff involved with the detailed risk evaluation, i.e., Phase 3 SDP analysis, recognized that use of the Appendix G guidance would have resulted in the subject finding screening to Green, but determined that this was not appropriate based on event-specific information. The Unit 1 stator drop event was very complex. It involved an extended loss of offsite power (LOOP) with many complications that occurred during a time when the electrical distribution systems were not in the normal alignment. This level of complexity necessitated a detailed risk evaluation using the Phase 3, quantitative SDP analysis tool. As described in the Panels report, Inspection Manual Chapters 0609 and 0308 recognize that these complex events can occur, and consequently allow the NRC to perform a detailed risk evaluation, i.e., Phase 3 SDP analysis, as necessary. This includes the flexibility to modify various modeling assumptions when the pre-specified imbedded assumptions are not appropriate to the finding. As specifically noted in IMC 0308, Phase 3 was defined to address the expected need to depart from the Phase 2 guidance when the Phase 2 modeling assumptions are known to be inaccurate or incomplete, and requires professional risk analysts to be involved in all such cases. While the 24-hour mission time prescribed in the Appendix G guidance for conducting Phase 1 and Phase 2 SDP analyses is generally applicable, the fact that offsite power was not recovered for six days caused this event and related finding to be outside the inherent assumptions of Appendix G for findings in POS 3. More specifically, given that it took approximately six days to recover offsite power and that upon a loss of DHR, it would have taken over three days for the core to become uncovered, modification of the mission time for the EDGs from the 24-hour time assumed in the IMC 0308 and IMC 0609 Appendix G guidance, to a 72-hour mission time, was appropriate.

You stated in your DPO submittal that the RASP Handbook is a sub-tier methods handbook that is required to be consistent with the IMCs. You also stated that in lieu of the instruction contained in IMC 0609, Appendix G, and IMC 0308, Attachment 3, Appendix G [specifically, that LOOP events are not assessed for POS 3 since the time to uncover the core is considered to be greater than 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months s], the analyst had followed other guidance contained in the RASP Handbook. Volume 1, Internal Events, and Volume 4, Shutdown Events, of the RASP Handbook provide guidance on appropriate adjustments to component, e.g., EDG, mission time dependent upon the duration of LOOP events. As noted by the Panel, the RASP Handbook contains guidance for performing various risk evaluations, and it states that it is not within the scope of the Handbook to repeat program-specific requirements, noting that if there is a conflict between the RASP Handbook and the IMCs, the program-specific

G. Replogle requirements supersede the RASP Handbook guidance. As documented in its report, the Panel did not view the general use of a 24-hour mission time per Appendix G in conducting a Phase 2 SDP evaluation as a program requirement. Instead, the Panel considered the use of a 24-hour mission time as generally appropriate for the SDP, but not a required assumption if it is not appropriate to the finding. Therefore, the Panel did not see a conflict between Appendix G and the RASP Handbook for the example provided involving EDG mission time.

In addition, as noted by the Panel, the detailed risk evaluation comprising the Phase 3 SDP analysis, including the greater than 24-hour mission time assumption, was peer reviewed by other risk analysts, reviewed by the Significance and Enforcement Review Panel, and also provided to the licensee for its review. Noting that none of these reviews challenged the mission time assumption, the Panel considered this fact as further evidence that deviating from the Appendix G guidance and increasing the mission time was reasonable for the subject inspection finding. It is my view that the Panel has applied sound logic as described above in arriving at its conclusion.

With respect to your concern that the RASP Handbook is not consistent with the ASME PRA standard regarding mission time, the Panel noted that the RASP Handbook is an NRC document intended for use in evaluating the safety significance of events and findings in connection with the Reactor Oversight Process and the Accident Sequence Precursor Program, whereas the ASME PRA standard is a document used to guide the development of baseline PRAs in estimating the overall risk from typical plant operations. I agree with the Panels conclusion that since the documents are references intended for different uses, it is not unreasonable to expect some differences in the way analysis input or assumptions are applied. Notwithstanding, as noted by the Panel, the differences in the guidance with respect to mission time were not substantive. I also agree with the Panels conclusion that the term safe, stable, state, used in the ASME PRA standard in the context of component mission time to achieve stable plant conditions, could be further explained in the RASP Handbook, as it would help NRC risk analysts recognize those situations where alternate assumptions regarding mission time or functional success criteria should be considered.

I noted that the Panel, in evaluating your concern that the RASP Handbook contains several pieces of inaccurate information, interviewed various agency staff and management to obtain their respective views on the purpose and intended application of the RASP Handbook. The Panel indicated in its report that all parties interviewed agreed that the RASP Handbook is a methods document that captures best practices for performing various risk assessments and is expected to evolve with use. These methodologies/best practices are oftentimes not specifically described, referenced, or addressed as program-specific requirements in the governing program documents such as IMCs 0609, 0308, and 0309, Reactive Inspection Decision Basis for Reactors. Lack of reference in the governing IMCs to a specific methodology/best practice contained in the RASP Handbook does not automatically mean that the subject methodology/best practice is inconsistent with program-specific requirements.

However, I do think it would be a prudent measure, as the Panel recommends, for the staff to conduct a comprehensive review of the RASP Handbook to ensure its guidance is consistent with existing program requirements. Of particular note, one of the recommendations from the DPO Panel established to review DPO-2014-002 was that, The staff should ensure that guidance in the RASP Handbook conforms with governing ROP documents. This could involve changes or clarifications to the RASP Handbook, to governing ROP documents, or to both the RASP Handbook and governing ROP documents. This DPO Panel recommendation was endorsed by the Director of NRR in his memorandum to the DPO

G. Replogle submitter dated November 21, 2014. As reflected in the decision for DPO-2014-002 and in the Panels report for DPO-2015-001, relevant staff and management in NRR agree that a comprehensive review of the RASP Handbook against the implementing requirements is warranted. Of note, this action is still outstanding and it has been 14 months since the decision on DPO-2014-002. Regarding DPO-2015-001, I also agree with the Panels view that risk analysts should continue to have the flexibility to apply risk assessment approaches/methodologies described in the RASP Handbook since it is in the best interest of furthering the application of risk technology. However, as the Panel noted, when applying this flexibility, if a situation arises where the approach identified in the RASP Handbook appears to be inconsistent with program-specific requirements, the risk analyst is obligated to follow up with appropriate staff/management to ensure that the intent of program requirements is satisfied.

With respect to your concerns that the review and approval process for the RASP Handbook is not rigorous and the associated change process is inadequate, I noted that you raised similar concerns in DPO-2014-002. Recommendation 6 from the DPO Panel established to review DPO-2014-002 was, A rigorous change control process should be adopted for incorporating changes to the RASP Handbook. This recommendation was endorsed by the NRR Director in his memorandum to the DPO submitter dated November 21, 2014. The Panels report for DPO-2015-001 indicates that the revised review and approval process for changes to the RASP Handbook that has been established by the NRRs Division of Risk Assessment in response to recommendation 6 from DPO-2014-002, represents a considerable improvement over the previous process. However, as noted by the Panel, the subject revised review and approval process has not yet been incorporated into the RASP Handbook.

Thank you for your active participation in the DPO process. Your willingness to raise concerns with our regulatory processes and associated outcomes via a DPO when previous discussions with staff and management on the involved issues did not result in satisfactory resolution, is important to ensuring a healthy safety culture within the agency. When the case is closed, a summary of the DPO and associated decision will be included in the Weekly Information Report to advise interested employees of the outcome. In addition, you will be included on correspondence involving the development/listing of follow up actions and associated implementation schedules.

Enclosure:

DPO Panel Report dated January 22, 2016 cc: W. Dean, NRR Patricia Holahan, OE R. Pedersen, OEI M. Sewell, OE J. Giitter, NRR K. Kennedy, Region IV M. Cheok, NRO R. Gibbs, NRR G. MacDonald, Region II L. Kozal, Region III