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
1 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
Hearing Identifier:
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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>
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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:
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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
September 6, 2017 TREATMENT OF FIRE HAZARDS IN 10 CFR 50.69 NEI 50.69 LAR Coordinating Committee Thomas Zachariah Senior Project Manager
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
LSS3 HSS2 LSS Identify System Boundary and Components Identify System Functions Evaluate Risk of Each Function1 Map Each Component to Function Collect System Operational Information on SSCs Evaluate Qualitative Risk of Components Evaluate Risk in Non-PRA Modeled Hazards Evaluate Risk in Shutdown Modes Component Risk from PRA Internal Events PRA Integrated Component Risk Component Risk from Other PRA Models HSS Perform Sensitivity Study HSS Perform Sensitivity Study HSS LSS HSS2 LSS HSS LSS HSS2 HSS LSS HSS Divide System into Pipe Segments Consequence Evaluation Deterministic Considerations Check for Sufficient Margin HSS2 LSS Preliminary Categorization Defense In Depth2 IDP Review Final HSS4 Final LSS LSS HSS LSS HSS HSS No Yes Yes No 1 Preliminary HSS if supporting Components are HSS from PRA Internal Events, PRA Integrated Risk 2 Cannot be overridden by IDP 3 Safety related HSS SSCs revised by the IDP to be LSS should be confirmed by the Defense in Depth Evaluation 4 Critical attributes should be determined for all final HSS components Qualitative Categorization Probabilistic Risk Assessment Categorization Passive Categorization HSS LSS 4
Evaluate Risk in Non-PRA Modeled Hazards
PRELIMINARY CATEGORIZATION 5
PRA Sensitivity Studies Support of a qualitative HSS system function Passive Risk Internal Events PRA Risk Support of primary methods for mitigating shutdown risk Candidate LSS SSCs have to be evaluated as low importance in the following areas HSS SSCs cannot be overridden by IDP Fire PRA Risk Seismic PRA Risk Appropriate Level of Defense-In-Depth Credited as Fire Safe Shutdown Components Credited on Seismic SSEL PRA Sensitivity Studies Internal Events PRA Risk Ca d date SS SSCs a e to be e a uate Fire PRA Risk Seismic PRA Risk Integrated PRA Risk PRA HSS SSCs can be downgraded by IDP with appropriate justification Or Or
CORE SPRAY SYSTEM 6
SEISMIC, 5%
PASSIVE, 18%
DID Core Damage, 43%
DID Containment, 16%
Combination, 17%
052 HSS Components by Process Element (exclusively)
IE PRA FIRE PRA SEISMIC External SHUTDOWN PASSIVE DID Core Damage DID Containment Combination 0
0 0
26 59 150 171 347 583 0
100 200 300 400 500 600 700 FIRE PRA EXTERNAL SHUTDOWN IE PRA SEISMIC PASSIVE DID CONTAINMENT DID CORE DAMAGE TOTAL Number of Components 052 HSS Components by Process Element
REACTOR ENCLOSURE HVAC 7
SEISMIC, 4%
DID Core Damage, 45%
Combination, 51%
076 HSS Components by Process Element (exclusively)
IE PRA FIRE PRA SEISMIC External SHUTDOWN PASSIVE DID Core Damage DID Containment QUAL Combination 0
0 162 162 291 388 866 1085 1100 2417 0
500 1000 1500 2000 2500 3000 EXTERNAL DID CONTAINMENT FIRE PRA IE PRA SEISMIC QUAL SHUTDOWN PASSIVE DID CORE DAMAGE TOTAL Number of Components 076 HSS Components by Process Element
OTHER CATEGORIZATION RESULTS 8
0%
0%
0%
4%
9%
25%
41%
73%
0%
10%
20%
30%
40%
50%
60%
70%
80%
EXTERNAL FIRE PRA IE PRA PASSIVE DID SHUTDOWN QUAL SEISMIC Percentage of Components Percentage of Vogtle HSS Components by Evaluation Based on 4 Categorized Systems (300 HSS SSCs)
Based on 98 Categorized* Systems (5864 HSS SSCs)
- 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
CHEMICAL VOLUME CONTROL SYSTEM CONTAINMENT SPRAY COMPARISON OF FIRE SSEL TO FIRE PRA (SITE A) 15 12 99 0
20 40 60 80 100 120 Additional Fire SSEL Components Fire PRA HSS Components 34 0
20 40 60 80 100 120 Additional Fire SSEL Components Fire PRA HSS Components
SITE B COMPARISON OF FIRE SSEL TO FIRE PRA 16 200 2000 0
500 1000 1500 2000 2500 Additional Fire SSEL Components 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 18 Use of the Fire SSEL provides a conservative alternative approach to addressing fire for 50.69 categorization