ML17249A072
| ML17249A072 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 09/05/2017 |
| From: | Zachariah T Nuclear Energy Institute |
| To: | Ed Miller Plant Licensing Branch II |
| References | |
| Download: ML17249A072 (22) | |
Text
NRR-PMDAPEm Resource From: Miller, Ed Sent: Wednesday, September 06, 2017 7:35 AM To: Miller, Ed
Subject:
Slides for Sept 6, 2017, Public Meeting Attachments: 50.69 Fire SSEL LAR Section Write up R1.docx; 50.69 Treatment of Fire Presentation.pdf Importance: High Attached are the slides for the September 6, 2017, Public Meeting on 10 CFR 50.69.
From: ZACHARIAH, Thomas [1]
Sent: Tuesday, September 05, 2017 4:14 PM To: Miller, Ed ; Rosenberg, Stacey
Subject:
[External_Sender] RE: 50.69 Fire SSEL LAR Section Write up Importance: High Ed, Stacey, Here is the industry presentation. We also made some minor updates to write up I sent.
- Thanks, Tom 1
Hearing Identifier: NRR_PMDA Email Number: 3710 Mail Envelope Properties (ddb82b4c8f5444c3817f0931b0111795)
Subject:
Slides for Sept 6, 2017, Public Meeting Sent Date: 9/6/2017 7:35:14 AM Received Date: 9/6/2017 7:35:17 AM From: Miller, Ed Created By: Ed.Miller@nrc.gov Recipients:
"Miller, Ed" <Ed.Miller@nrc.gov>
Tracking Status: None Post Office: HQPWMSMRS02.nrc.gov Files Size Date & Time MESSAGE 424 9/6/2017 7:35:17 AM 50.69 Fire SSEL LAR Section Write up R1.docx 164912 50.69 Treatment of Fire Presentation.pdf 488780 Options Priority: High Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received:
3.2.1 Fire Hazards The [PLANT NAME] categorization process will use the Fire Safe Shutdown Equipment List (SSEL) with the consideration of fire-induced Multiple Spurious Operations (MSOs) for evaluation of safety significance related to fire hazards. Though this approach is a deviation from the NEI 00-04 endorsed approaches, it is an approach that is more conservative in determining safety significance than the use of a Fire PRA or the NEI 00-04 FIVE approach. Similar to the NEI 00-04 FIVE approach, this approach uses the component list as a screening tool. However, unlike FIVE, the development of the Fire SSEL is not based on a successive screening methodology. The Fire Safe Shutdown paths identify the safety functions and associated sets of equipment required to achieve and maintain safe shutdown under postulated fire conditions as defined by 10 CFR 50, Appendix R, Fire Protection Program for Nuclear Power Facilities Operating Prior to January 1, 1979 (Reference X) and NRC Branch Technical Position CMEB 9.5-1, "Guidelines for Fire Protection for Nuclear Power (Reference Y). The Fire SSEL identifies the credited equipment on these Fire Safe Shutdown Paths.
Since this is a screening approach, there are no importance measures used in determining safety significance related to the fire hazard. Instead, using the Fire SSEL would identify all credited equipment as HSS regardless of their fire damage susceptibility or frequency of challenge. This approach ensures the SSCs that have been determined to be required to establish and maintain safe shutdown capability are retained as safety-significant. Figure 3-1 illustrates how the Fire SSEL is reviewed to determine if the component being evaluated is HSS. If a component is credited on the Fire SSEL , it is considered HSS. Furthermore, previously identified fire-induced MSOs were reviewed and it was concluded that no equipment in addition to the components on the Fire SSEL are required to mitigate those MSOs. Therefore, no additional components will be identified as HSS with regard to the fire hazard. The results of this review are available for NRC audit. OR Furthermore, identified fire-induced MSOs were reviewed and the equipment that is required to mitigate those MSOs, in addition to the Fire SSEL components, will be retained as HSS. The results of this review are available for NRC audit.
The [LICENSEE] Fire Safe Shutdown program is an active regulatory program which is routinely inspected. It was confirmed that this program ensures that the Fire SSEL reflects the current as-built, as-operated plant and that changes to the plant will be evaluated to determine their impact to the component list and the categorization process.
Figure 3-1: Safety Significance Process for Systems and Components Addressed in Fire Safe Shutdown Program
TREATMENT OF FIRE HAZARDS IN 10 CFR 50.69 NEI 50.69 LAR Coordinating Committee Thomas Zachariah Senior Project Manager September 6, 2017
CATEGORIZATION 2
NEI 00-04 RISK INFORMED CATEGORIZATION
- Each of the elements below determines a separate categorization of the SSC used in the final categorization by the IDP
- Qualitative risk assessment of supported system functions
- Non-PRA modeled external hazard risk
- Shutdown risk assessments
- Probabilistic Risk Assessments
- Passive categorization
- Defense-in-depth assessments
- The full process is applied to all components in a selected system must be categorized 3
Qualitative Categorization Identify System Evaluate Risk of Each HSS 1 Preliminary HSS if supporting Functions Function 1 LSS Components are HSS from PRA Internal Events, PRA Integrated Collect System Risk Map Each Component Evaluate Qualitative HSS Operational to Function Information on SSCs Risk of Components LSS 2 Cannot be overridden by IDP 3
Safety related HSS SSCs revised by Evaluate Risk in Non- Evaluate Risk in HSS2 the IDP to be LSS should be PRA Modeled Hazards Shutdown Modes LSS confirmed by the Defense in Depth Evaluation Probabilistic Risk Assessment Categorization 4 Critical attributes should be determined for all final HSS No Perform Sensitivity HSS components Study LSS Identify System Component Risk from Yes Preliminary Boundary and PRA Internal Events HSS HSS2 Categorization Components PRA Integrated HSS2 Component Risk LSS Component Risk from Yes LSS HSS Other PRA Models HSS HSS Defense In LSS 2 IDP Review No Perform Sensitivity HSS Depth Study LSS HSS Passive Categorization HSS LSS3 Divide System Check for Consequence Deterministic HSS2 Final Final 4 into Pipe Segments Evaluation Considerations Sufficient Margin LSS HSS4 LSS
PRELIMINARY CATEGORIZATION Candidate Ca d date LSS SS SSCs have a e to be evaluated e a uate as low importance in the following areas Credited as Fire Support of a Internal Events Fire PRA Risk Or Safe Shutdown qualitative HSS PRA Risk Components system function Support of primary PRA Sensitivity Seismic PRA Credited on methods for Or mitigating shutdown Studies Risk Seismic SSEL risk Appropriate Level Integrated PRA Passive Risk of Defense-In-Risk PRA Depth HSS SSCs cannot be overridden by IDP 5 HSS SSCs can be downgraded by IDP with appropriate justification
CORE SPRAY SYSTEM 052 HSS Components by Process 052 HSS Components by Process Element (exclusively) Element Combination, SEISMIC, 5%
17% TOTAL 583 IE PRA DID CORE DAMAGE 347 FIRE PRA DID CONTAINMENT 171 SEISMIC PASSIVE 150 PASSIVE, 18% External SEISMIC 59 DID SHUTDOWN IE PRA 26 Containment, PASSIVE SHUTDOWN 0 16%
DID Core Damage EXTERNAL 0 DID Containment FIRE PRA 0 DID Core Combination 0 100 200 300 400 500 600 700 Damage, 43%
Number of Components 6
REACTOR ENCLOSURE HVAC 076 HSS Components by Process 076 HSS Components by Process Element (exclusively) Element SEISMIC, 4%
TOTAL 2417 IE PRA DID CORE DAMAGE 1100 FIRE PRA PASSIVE 1085 SEISMIC SHUTDOWN 866 External QUAL 388 SHUTDOWN SEISMIC 291 DID Core IE PRA Combination, PASSIVE 162 Damage, 45%
51% DID Core Damage FIRE PRA 162 DID Containment DID CONTAINMENT 0 QUAL EXTERNAL 0 Combination 0 500 1000 1500 2000 2500 3000 Number of Components 7
OTHER CATEGORIZATION RESULTS Based on 4 Categorized Systems (300 HSS SSCs) Based on 98 Categorized* Systems (5864 HSS SSCs)
Percentage of Vogtle HSS Components by Evaluation SEISMIC 73%
QUAL 41%
SHUTDOWN 25%
DID 9%
PASSIVE 4%
FIRE PRA 0%
EXTERNAL 0%
0% 10% 20% 30% 40% 50% 60% 70% 80%
Percentage of Components 8 *Not Categorized with NEI 00-04 Process
NON-PRA MODELED HAZARDS
ACTIVE RISK FROM NON-PRA MODELED HAZARDS
- For any hazards (e.g., fire, seismic, other external events) that are not modeled in the PRA, the results of the hazards evaluations (bounding, qualitative, or screening) can be used.
- Seismic Margins Analysis (SMA) Safe Shutdown Equipment List (SSEL)
- FIVE Credited Components or Fire SSEL
- Other External Hazard Screening 10
FIRE INDUCED VULNERABILITY EVALUATION (FIVE)
- Endorsed Approach by RG 1.201
- No importance measures from the evaluation are used in categorization
- HSS components are identified by determining if:
- A component is credited in an unscreened FIVE scenario, OR
- Removal of a component from a screened FIVE scenario would make the scenario unscreened
- Availability of historical information and data makes this approach not practical 11
FIRE SAFE SHUTDOWN EQUIPMENT LIST
- An alternate proposed process from NEI 00-04 endorsed approaches
- Similar to SMA SSEL approach, HSS components are identified by determining if the component is credited on the Fire SSEL
- Approach is conservative compared to FIVE since it does not use a successive screening methodology 12
FIRE SAFE SHUTDOWN EQUIPMENT LIST
- The Fire Safe Shutdown program is the active regulatory program required to maintain safe shutdown capability during fire events
- Program is routinely inspected and ensures that the Fire SSEL reflects the as built as operated plant
- Additional components, if any, required to mitigate Multiple Spurious Operations (MSO) will be retained as HSS 13
FIRE SAFE SHUTDOWN EQUIPMENT LIST 14
COMPARISON OF FIRE SSEL TO FIRE PRA (SITE A)
CHEMICAL VOLUME CONTROL CONTAINMENT SPRAY SYSTEM 120 120 100 100 80 80 60 99 60 40 40 20 20 34 12 0 0 Additional Fire SSEL Components Additional Fire SSEL Components 15 Fire PRA HSS Components Fire PRA HSS Components
COMPARISON OF FIRE SSEL TO FIRE PRA SITE B 2500 2000 1500 2000 1000 500 0
200 Additional Fire SSEL Components 16 Fire PRA HSS Components
COMPARISON OF FIRE SSEL TO FIRE PRA (SITE B & C) - RESULTS
- Final determination for these sites was that a RG 1.200 fire PRA model did not identify any additional components that wouldnt be already driven HSS by
- A RG 1.200 Internal Events PRA
- Identified components on Fire SSEL
- Required components for MSO mitigation 17
CONCLUSION Use of the Fire SSEL provides a conservative alternative approach to addressing fire for 50.69 categorization 18