ML17349A926

EA-13-109 Vent Order Audit Report

ML17349A926
Person / Time
Site:	Dresden
Issue date:	12/20/2017
From:	Rajender Auluck Beyond-Design-Basis Engineering Branch
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
Lee B
References
CAC MF4462, CAC MF4463, EPID L-2014-JLD-0047
Download: ML17349A926 (24)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 20, 2017 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 - REPORT FOR THE AUDIT OF LICENSEE RESPONSES TO INTERIM STAFF EVALUATIONS OPEN ITEMS RELATED TO NRC ORDER EA-13-109 TO MODIFY LICENSES WITH REGARD TO RELIABLE HARDENED CONTAINMENT VENTS CAPABLE OF OPERATION UNDER SEVERE ACCIDENT CONDITIONS (CAC NOS. MF4462 AND MF4463; EPID L-2014-JLD-0047)

Dear Mr. Hanson:

On June 6, 2013 (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML13143A334), the U.S. Nuclear Regulatory Commission (NRC) issued Order EA-13-109, "Order to Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Condition," to all Boiling Water Reactor licensees with Mark I and Mark II primary containments. The order requirements are provided in Attachment 2 to the order and are divided into two parts to allow for a phased approach to implementation. The order required licensees to submit for review overall integrated plans (OIPs) that describe how compliance with the requirements for both phases of Order EA-13-109 will be achieved.

By letter dated June 30, 2014 (ADAMS Accession No. ML14184A018), Exelon Generation Company, LLC. (the licensee) submitted its Phase 1 OIP for Dresden Nuclear Power Station, Units 2 and Unit 3 (Dresden). By letters dated December 17, 2014, June 30, 2015, December 16, 2015 (which included the combined Phase 1 and Phase 2 OIP), June 30, 2016, December 14, 2016, and June 27, 2017 (ADAMS Accession Nos. ML14351A442, ML15181A220, ML15352A027, ML16182A393, ML17353A045, and ML17178A078, respectively), the licensee submitted its 6-month updates to the OIP. The NRC staff reviewed the information provided by the licensee and issued interim staff evaluations (ISEs) for Phase 1 and Phase 2 of Order EA-13-109 for Dresden by letters dated February 11, 2015 (ADAMS Accession No. ML15007A491), and September 30, 2016 (ADAMS Accession No. ML16273A430), respectively. When developing the ISEs, the staff identified open items where the staff needed additional information to determine whether the licensee's plans would adequately meet the requirements of Order EA-13-109.

The NRC staff is using the audit process described in letters dated May 27, 2014 (ADAMS Accession No. ML14126A545), and August 10, 2017 (ADAMS Accession No. ML17220A328),

to gain a better understanding of licensee activities as they come into compliance with the order.

As part of the audit process, the staff reviewed the licensee's closeout of the ISE open items.

B. Hanson The NRC staff conducted teleconferences with the licensee on June 1, 2017, and December 7, 2017, respectively. The enclosed audit report provides a summary of that aspect of the audit.

If you have any questions, please contact me at 301-415-1025 or by electronic mail at Rajender.Auluck@nrc.gov.

Sincerely, Rajender Auluck, Senior Project Manager Beyond-Design-Basis Engineering Branch Division of Licensing Projects Office of Nuclear Reactor Regulation Docket Nos. 50-237 and 50-249

Enclosure:

Audit report cc w/encl: Distribution via Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 AUDIT REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION AUDIT OF LICENSEE RESPONSES TO INTERIM STAFF EVALUATIONS OPEN ITEMS RELATED TO ORDER EA-13-109 MODIFYING LICENSES WITH REGARD TO RELIABLE HARDENED CONTAINMENT VENTS CAPABLE OF OPERATION UNDER SEVERE ACCIDENT CONDITIONS EXELON GENERATION COMPANY, LLC DRESDEN NUCLEAR POWER STATION, UNITS 2 AND 3 DOCKET NOS. 50-237 AND 50-249 BACKGROUND On June 6, 2013 (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML13143A334), the U.S. Nuclear Regulatory Commission (NRC) issued Order EA-13-109, "Order to Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Condition," to all Boiling Water Reactor (BWR) licensees with Mark I and Mark II primary containments. The order requirements are divided into two parts to allow for a phased approach to implementation.

Phase 1 of Order EA-13-109 requires license holders of BWRs with Mark I and Mark II primary containments to design and install a Hardened Containment Vent System (HCVS), using a vent path from the containment wetwell to remove decay heat, vent the containment atmosphere (including steam, hydrogen, carbon monoxide, non-condensable gases, aerosols, and fission products), and control containment pressure within acceptable limits. The HCVS shall be designed for those accident conditions (before and after core damage) for which containment venting is relied upon to reduce the probability of containment failure, including accident sequences that result in the loss of active containment heat removal capability or extended loss of alternating current power (ELAP). The order required all applicable licensees, by June 30, 2014, to submit to the Commission for review an overall integrated plan (OIP) that describes how compliance with the Phase 1 requirements described in Order EA-13-109 Attachment 2 will be achieved.

Phase 2 of Order EA-13-109 requires license holders of BWRs with Mark I and Mark II primary containments to design and install a system that provides venting capability from the containment drywell under severe accident conditions, or, alternatively, to develop and implement a reliable containment venting strategy that makes it unlikely that a licensee would need to vent from the containment drywell during severe accident conditions. The order required all applicable licensees, by December 31, 2015, to submit to the Commission for Enclosure

review an OIP that describes how compliance with the Phase 2 requirements described in Order EA-13-109 Attachment 2 will be achieved.

By letter dated June 30, 2014 (ADAMS Accession No. ML14184A018), Exelon Generation Company, LLC. (the licensee) submitted its Phase 1 OIP for Dresden Nuclear Power Station, Units 2 and Unit 3 (Dresden). By letters dated December 17, 2014, June 30, 2015, December 16, 2015 (which included the combined Phase 1 and Phase 2 OIP), June 30, 2016, December 14, 2016, and June 27, 2017 (ADAMS Accession Nos. ML14351A442, ML15181A220, ML15352A027, ML16182A393, ML17353A045, and ML17178A078, respectively), the licensee submitted its 6-month updates to the OIP, as required by the order.

The staff reviewed the information provided by the licensee and issued interim staff evaluations (ISEs) for Phase 1 and Phase 2 for Dresden by letters dated February 11, 2015 (ADAMS Accession No. ML15007A491 ), and September 30, 2016 (ADAMS Accession No. ML16273A430), respectively. When developing the ISEs, the staff identified open items where the staff needed additional information to determine whether the licensee's plans would adequately meet the requirements of Order EA-13-109.

The NRC staff is using the audit process in accordance with the letters dated May 27, 2014 (ADAMS Accession No. ML14126A545), and August 10, 2017 (ADAMS Accession No. ML17220A328), to gain a better understanding of licensee activities as they come into compliance with the order. The staff reviews submitted information, licensee documents (via ePortals), and preliminary Overall Program Documents (OPDs)/OIPs, while identifying areas where additional information is needed. As part of this process, the staff reviewed the licensee closeout of the ISE open items.

AUDIT

SUMMARY

As part of the audit, the NRC staff conducted teleconferences with the licensee on June 1, 2017, and December 7, 2017, respectively. The purpose of the audit teleconferences was to continue the audit review and provide the NRC staff the opportunity to engage with the licensee regarding the closure of open items from the ISEs. As part of the preparation for these audit calls, the staff reviewed the information and/or references noted in the OIP updates to ensure that closure of ISE open items and the HCVS design are consistent with the guidance provided in Nuclear Energy Institute (NEI) 13-02, Rev. 1 and related documents (e.g. white papers (ADAMS Accession Nos. ML14126A374, ML14358A040, ML15040A038 and ML15240A072, respectively) and frequently asked questions (FAQs), (ADAMS Accession No. ML15271A148)) that were developed and reviewed as part of overall guidance development.

The NRC staff audit members are listed in Table 1. Table 2 is a list of documents reviewed by the staff. Table 3 provides the status of the ISE open item closeout for Dresden. The open items are taken from the Phase 1 and Phase 2 ISEs issued on February 11, 2015, and September 30, 2016, respectively.

FOLLOW UP ACTIVITY The staff continues to audit the licensee's information as it becomes available. The staff will issue further audit reports for Dresden, as appropriate.

Following the licensee's declarations of order compliance, the licensee will provide a final integrated plan (FIP) that describes how the order requirements are met. The NRC staff will

evaluate the FIPs, the resulting site-specific OPDs, as appropriate, and other licensee documents, prior to making a safety determination regarding order compliance.

CONCLUSION This audit report documents the staff's understanding of the licensee's closeout of the ISE open items, based on the documents discussed above. The staff notes that several of these documents are still preliminary, and all documents are subject to change in accordance with the licensee's design process. In summary, the staff has no further questions on how the licensee has addressed the ISE open items, based on the preliminary information. The status of the NRG staff's review of these open items may change if the licensee changes its plans as part of final implementation. Changes in the NRG staff review will be communicated in the ongoing audit process.

Attachments:

1. Table 1 - NRG Staff Audit and Teleconference Participants

2. Table 2 - Audit Documents Reviewed

3. Table 3 - ISE Open Item Status Table

Table 1 - NRC Staff Audit and Teleconference Participants Title Team Member Organization Team Lead/Sr. Project Manaaer Raiender Auluck NRR/DLP Project Manager Support/Technical Support - Containment / Ventilation Brian Lee NRR/DLP Technical Support - Containment/

Ventilation Bruce Heida NRR/DLP Technical Support - Electrical Kerby Scales NRR/DLP Technical Support- Balance of Plant Kevin Roche NRR/DLP Technical Support - l&C Steve Wyman NRR/DLP Technical Support - Dose John Parillo NRR/DRA Attachment 1

Dresden Nuclear Power Station, Units 2 and 3 Vent Order Interim Staff Evaluation Open Items:

Table 3 - ISE Open Item Status Table ISE Open Item Number Licensee Response - Information NRC Staff Close-out notes Safety Evaluation (SE) provided in 6 month updates and on the status Requested Action ePortal Closed; Pending; Open (need additional information from licensee)

Phase 1 ISE 01 1 EC 391973 Rev. 0 was completed to The NRC staff reviewed the Closed evaluate proposed battery load shed to information provided in the 6-Make available for NRC staff support FLEX events. The evaluation month updates and on the [Staff evaluation to be audit documentation addressed both 125V and 250V battery ePortal. included in SE Section confirming that at least 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> systems. The evaluation identified that 3.1.2.6]

battery coping time is available with the load shed, the 125V and 250V Each unit at Dresden has one for instrumentation. batteries will maintain acceptable capacity 125 Volt (V) direct current (de) for a minimum of six (6) hours. This time safety-related main station battery supports the FLEX Strategy time line and one 250 Vdc safety-related actions. station battery.

EC 391973 is available for NRC review on The battery coping time with load the ePortal. shedding evaluation (EC 391973) verified the capability of the de system to supply power to the required loads during the first phase of the Dresden FLEX mitigation strategy plan for an ELAP as a result of a beyond-design-basis external event (BDBEE). The licensee's evaluation identified the required loads and their associated ratings (ampere (A) and minimum required voltage) and the non-essential loads that would be shed within 30 minutes to ensure battery operation for at least 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

Attachment 3

No follow-up questions.

Phase 1 ISE 01 2 EC 391644 has been completed to The NRC staff reviewed the Closed provide flood barriers for the Reactor information provided in the 6-Make available for NRC staff Building under a flood event prediction. month updates and on the [Staff evaluation to be audit documentation that The barriers will be installed to keep the ePortal. included in SE Section confirms the ability to operate flood waters from entering the 3.0]

HCVS following flooding suppression pool and challenging the The licensee has implemented around the suppression pool. functionality of the suppression pool vent. the design and installation of Additionally, an Engineering Evaluation deployable flood barriers and (EC 407086) has been completed to permanent penetration ensure that any flood water in-leakage - seals/closures in order to protect does not rise to a level where it can enter the critical structures (including the suppression pool via the vacuum the operability of the suppression breakers. pool vent) from the design-basis probable maximum flood. In The 50.59 Evaluation for EC 391644 and addition, engineering evaluation EC 407086 have been uploaded to EC 407086 indicates that ePortal for NRC review. any flood water in-leakage will not rise to a level where it can enter the suppression pool via the vacuum breakers.

No follow-up questions.

Phase 1 ISE 01 3 HCVS design precludes inadvertent The NRC staff reviewed the Closed actuation of the system through passive information provided in the 6-Make available for NRC staff design features. The HCVS vent pipe has month updates and on the [Staff evaluation to be audit documentation of a been designed with two PCIVs [primary ePortal. included in SE Section method to disable HCVS containment isolation valves], in series, in 3.1.2.7]

during normal operation to compliance with GDC-56. The PCIVs The HCVS wetwell pipe in each provide assurances against have independent actuation trains, unit contains two PCIVs, in series, inadvertent operation that also thereby precluding inadvertent actuation which are isolated from their minimizes actions to enable by a single component failure or mis- motive force supply by two locked HCVS operation following an alignment. Each PCIV isolates the vent closed manual valves and require ELAP. line through its normally held closed remote manual operation of a actuator spring. A rupture disk in the vent key-lock on the control switch at line downstream of the PC IVs preserves the primary operating station. In the secondary containment boundary. addition, there are no interfacing Furthermore, to prevent inadvertent systems downstream of the openinq, the PCIVs are isolated from their PCIVs, so inadvertent venting

motive force supply by two locked closed cross flow can not occur. The manual valves and require remote manual staff's review of the proposed operation of a key-lock on the control system indicates that the switch at the primary operating station. licensee's design appears to Similarly, purge gas supply is isolated preclude inadvertent actuation.

from the vent line by two locked closed manual valves and requires remote No follow-up questions.

manual operation of a key-lock on the control switch at the primary operating station. Since there are no interfacing systems downstream of the PCIVs, no inadvertent venting cross flow can occur.

Details on the configuration of the vent line PCIVs can be found in EC 401069, Design Considerations Summary (DCS).

Sections 4.1.4.1, 4.1.4.1.5 and 4.1.27.

Based on the details in the EC, NEI requirements 4.1.2.1 and 4.2.1, to prevent inadvertent actuation of the system, are met.

EC 401069 is available for NRC review on the ePortal.

Phase 1 ISE 01 4 Dresden does not require the The NRC staff reviewed the Closed consideration of contingencies discussed information provided in the 6-Make available for NRC staff in Assumption No. 3 in HCVS white paper month updates and on the [Staff evaluation to be audit the seismic and tornado HCVS-WP-04. The Dresden HCVS vent ePortal. included in SE Section missile final design criteria for pipes external to the missile-protected 3.2.2]

the HCVS stack. structure were installed greater than 30 EC400578 addresses the HCVS feet above grade supported by a robust seismic qualification and tornado structural steel tower and have a target missile design.

area less than -300 ft2. The pipes are 1O" diameter Schedule 40 steel pipes. The licesee evaluated the entire Dresden's HCVS systems are enveloped HCVS system to Seismic by the assumptions in the generic Catergory I, which is consistent evaluation in Section 3 of HCVS-WP-04 with the plant's seismic design-and it is, therefore, concluded that the basis.

HCVS is unlikely to be damaged in a manner that prevents containment venting For the tornado missile design, by a wind-Qenerated missile from the the licensee assumed the plant

same wind event that generates an ELAP licensing basis tornado missiles.

or LUHS. The HCVS exits the plant structure approximately 50 feet In addition to the reasonable assurance above grade which is greater than evaluation in HCVS-WP-04; Dresden has the 30 feet assumed in the two design basis missiles, the 1" diameter guidance for large tumbling wind by 3 feet long steel rod (8 lbs.) and the generated missiles. Above 30 13.5" diameter by 35 feet long utility pole feet, the vent piping is enclosed (1490 lbs.). Large mass tornado missiles within a large structural steel are not considered credible above an tower. The tower will provide elevation of 30 feet above grade, as some protection from large wind discussed in HCVS-WP-04 and in the generated missiles. Smaller Design Considerations Summary (DCS) missiles may puncture the vent Section 4.1.38 of EC 400578. Therefore, piping, but should not crimp the only the 1" diameter steel rod missile is piping preventing flow.

considered above 30 feet elevation.

Dresden's HCVS pipe thickness is No follow-up questions.

nominally 0.365" thick and the thickness of steel required to stop the 1" diameter steel rod missile is 1" thick steel.

Therefore, the missile would penetrate the pipe section but is unlikely to crimp the pipe. This is discussed in the design criteria for the HCVS external piping and supporting structure in the DCS Section 4.1.38 of EC 400578.

Ref. DRE 15-0038 and EC-400578, OIP Plant Specific Assumption #4.

Phase 1 ISE 01 5 Calculation DRE15-0046 uses a RELAP5 The NRC staff reviewed the Closed model to determine that a 10-inch information provided in the 6-Make available for NRC staff diameter vent is' sufficient to remove 1% month updates and on the [Staff evaluation to be audit documentation of the reactor thermal power. ePortal. included in SE Section licensee design effort to 3.1.2.1]

confirm the diameter on the Calculation DRE15-0046 is available for The licesee provided calculation new common HCVS piping. NRC review on the ePortal. DRE15-0046, which shows that the size of the wetwell portion of the HCVS (10 inch diameter) provides adequate capacity to meet or exceed the order criteria.

No follow-up questions.

Phase 1 ISE 01 6 Calculation DRE15-0046 uses a RELAP5 The NRC staff reviewed the Closed model to determine that a 10-inch information provided in the 6-Make available for NRC staff diameter vent is sufficient to remove 1% month updates and on the [Staff evaluation to be audit analyses demonstrating reactor thermal power. The steady state ePortal. included in SE Section that HCVS has the capacity to venting capacity of the Dresden HCVS 3.1.2.1]

vent the steam/energy was determined at a torus vapor space Calculation DRE-15-0046 equivalent of one percent of pressure of 47 psig [per square inch determined the mass flow rate of licensed/rated thermal power gauge], which corresponds to the PCPL 110,381 lbm/hr to be the (unless a lower value is for the torus filled with water. At a torus minimum flow to remove the justified), and that the pressure of 47 psig, the HCVS can vent equivalent of 1% rated thermal suppression pool and the 111 ,071 lbm/hr of steam. At 1% reactor power.

HCVS together are able to thermal power the required vent capacity absorb and reject decay heat, is 110,381 lbm/hr. No follow-up questions.

such that following a reactor shutdown from full power Calculation DRE15-0046 is available for containment pressure is NRC review on the ePortal.

restored and then maintained below the primary containment design pressure and the primary containment pressure limit.

Phase 1 ISE 01 7 Dresden has designed and installed an The NRC staff reviewed the Closed argon purge system per EC 400578 to information provided in the 6-Provide a description of the address hydrogen detonation and month updates and on the [Staff evaluation to be final design of the HCVS to deflagration requirements of NEI 13-02 ePortal. included in SE Section address hydrogen detonation Rev. 1 for Unit 3 and will install for Unit 2. 3.1.2.11]

and deflagration. The design meets HCVS-WP-03 The licensee's design is requirements. consistent with Option 3 of the endorsed white paper HCVS-WP-HCVS-WP-03 and the DCS Section of EC 03.

400578 are available for NRC review on the ePortal. No follow-up questions.

Phase 1 ISE 01 8 Calculation DRE16-0028 performed an The NRC staff reviewed the Closed evaluation for adequacy of the ROS information provided in the 6-Make available for NRC staff location including seismic interaction of month updates and on the [Staff evaluation to be audit documentation of a the structure above the ROS location. EC ePortal. included in SE Section description of the final ROS 403549 performed an evaluation for 3.2.2]

location and a determination of

seismic adequacy for the ROS seismic interaction of nearby SSCs in the The ROS is in a location that is location. ROS location. readily accessible and seismically adequate (based on calculation These documents are available for NRC DRE16-0028), and appears to review on the ePortal. support operation of the HCVS.

No follow-up questions.

Phase 1 ISE 01 9 FSG-39, FLEX Communications Options, The NRC staff reviewed the Closed discusses the available Onsite information provided in the 6-Make available for NRC staff communications. Communications may month updates and on the [Staff evaluation to be audit documentation that be performed using the installed sound ePortal. included in SE Section demonstrates adequate powered headset system within the power 3.1.1.1]

communication between the block and 800 Mhz [megahertz] radios in The communication methods are remote HCVS operation the talkaround mode. Public Address the same as accepted in Order locations and HCVS decision announcements are made by Nuclear EA-12-049.

makers during ELAP and Security Officers using hand-held severe accident conditions. bullhorns. No follow-up questions.

Offsite communications will utilize hand-held satellite phones staged in the Control Room and Technical Support Center.

Battery chargers for portable communications equipment are stored in a robust structure. Upon initiation of the ELAP, the FLEX Diesel Generator can power the battery chargers.

FSG-39 is available for NRC review on the ePortal.

Phase 1 ISE 01 10 As described in the OIP, the HCVS torus The NRC staff reviewed the Closed vent path in each Dresden unit, starting at information provided in the 6-Provide a description of the and including the downstream Primary month updates and on the [Staff evaluation to be strategies for hydrogen control Containment Isolation Valve (PCIV), will ePortal. included in SE Section that minimizes the potential for be a dedicated HCVS flow path. There 3.1.2.12]

hydrogen gas migration and are no interconnected systems The HCVS wetwell pipe in each ingress into the reactor downstream of the downstream dedicated each unit provides a dedicated building or other buildings. HCVS PCIV. Interconnected systems are HCVS flowpath from the wetwell upstream of the downstream HCVS PCIV penetration PCIVs to the outside and are isolated by normally shut, fail shut with no interconnected PCIVs which, if open, would shut on an downstream piping. The staff's

ELAP. There is no shared HCVS piping review of the proposed system between the two units. As a result, the indicates that the licensee's potential for hydrogen gas migration and design appears to maintain ingress into the reactor building or other hydrogen below flammability buildings is minimized. limits.

No follow-up questions.

Phase 1 ISE 01 11 As described in ISE item 10 response, The NRG staff reviewed the Dresden's piping layout minimizes the information provided in the 6-Provide design details that possibility of cross flow of vented fluids month updates and on the minimize unintended cross within a unit and between the two units. ePortal.

flow of vented fluids within a unit and between units on the The licesee's design appears to site. minimize the unintended cross flow of vented fluids.

No follow-up questions.

Phase 1 ISE 01 12 DRE16-0010 has been completed and The NRG staff reviewed the Closed documents dose assessment results for information provided in the 6-Make available for NRG staff designated areas outside of primary month updates and on the [Staff evaluation to be audit an evaluation of containment that acceptably support the ePortal. included in SE Sections temperature and radiological sustained operation of the wetwell 3.1.1 .2 and 3.1.1.3]

conditions to ensure that containment system. The DCS section Main Control Room temperatures operating personnel can safely 4.1.14 for EC 400578 documents the have been addressed as part of access and operate controls environmental conditions. the FLEX order and were found to and support equipment. be acceptable by the NRG staff.

These documents are available for NRG review on the ePortal. EC 400578 Section 4.1.14 discusses the operability based on the environmental qualification for the new equipment and existing equipment.

During the December 7, 2017, audit call the licensee indicated most HCVS actions will take place in the main control room.

When manual actions are needed in ROS, an operator will be dispatched from MGR to perform

the specific task. Stay time in ROS will be limited. Procedures identify requirements for hot area work. Ice vests will be available as needed.

Temperature and radiological conditions should not inhibit operator actions needed to initiate and operate the HCVS during an ELAP with severe accident conditions.

No follow-up questions.

Phase 1 ISE 01 13 Calculation DRE15-0056 sizes the 125 The NRC staff reviewed the Closed VDC battery/battery charger required to information provided in the 6-Make available for NRC staff power the Unit 2 and Unit 3 Hardened month updates and on the [Staff evaluation to be audit the final sizing evaluation Containment Vent System ePortal. included in SE Section for HCVS batteries/battery (HCVS) components for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. 3.1.2.6]

charger including incorporation The licensee stated that all into FLEX DG [diesel The DCS section 4.1.35 for EC 400578 electrical power required for generator] loading calculation. discusses re-powering of the HCVS operation of HCVS components is battery charger using a FLEX portable provided by the 125 VDC DG. battery/battery charger.

The calculation is available for NRC The battery sizing calculation review on the ePortal. (DRE15-0056) confirmed that the HCVS batteries have a minimum capacity capable of providing power for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> without recharging, and therefore is adequate.

The licensee provided DCS Section 4.1.35 for EC 400578, which discusses re-powering of the HCVS battery charger using a FLEX portable DG.

No follow-up questions.

Phase 1 ISE 0114 The nitrogen pneumatic design is The NRC staff reviewed the Closed described in EC 400578 DCS section information provided in the 6-Make available for NRC staff 4.1 .33. For Unit 3, two nitrogen bottles month updates and on the [Staff evaluation to be audit documentation of the are provided to operate 3-1601-60 and 3- ePortal. included in SE Section HCVS nitrogen pneumatic 1601-93 valves. The primary operating 3.1.2.6]

system design including sizing location for the nitrogen system is the EC 400578, DCS Section 4.1.33 and location. MCR via solenoid operated valves. and EC 401069 discussed the Additionally, the nitrogen system can be pneumatic design and sizing.

activated from the ROS by opening valves Two N2 bottles are provided for manually. operation of HCVS valves. The evaluation determined that 2640 EC 400578 DCS is available for NRC psig in each N2 bottle, will have review on the ePortal. sufficient capacity to operate the HCVS for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Phase 1 ISE 01 15 Existing plant instruments that meet the The NRC staff reviewed the Closed requirements of RG 1.97 or equivalent are information provided in the 6-Make available for NRC staff considered qualified for the sustained month updates and on the [Staff evaluation to be audit descriptions of all operating period without further ePortal. included in SE Section instrumentation and controls evaluation. The following plant 3.1.2.8]

(existing and planned) instruments required for HCVS that The existing plant instuments necessary to implement this meet the requirements of RG 1.97: required for HCVS (i.e. wetwell order including qualification level instruments and drywell methods. 2(3)-1641-5A (div I) and 2(3)-1641-58 (div pressure instruments) meet the II) Wetwell Level Instruments. requirements of RG 1.97.

2(3)-1641-6A (div I) and 2(3)-1641-68 (div EC 400578 and EC 401069

11) Drywell Pressure Instruments. discusses the seismic qualifications for new HCVS l&C New HCVS Instrumentation is discussed components. The staff's review in detail within the DCS sections of EC indicated that the seismic 400578 and EC 401069. The HCVS qualification met the order instruments are either qualified by seismic requirements.

shake table testing and/or analysis as discussed in the DCS of the ECs. These No follow-up questions.

sections of the ECs are available for NRC review on the ePortal.

Phase 1 ISE 01 16 The DCS of ECs 400578 and 401069 are The NRC staff reviewed the Closed available for NRC review on the ePortal. information provided in the 6-Make available for NRC staff DCS section 4.1 .14 provides detail on month updates and on the audit the descriptions of local environmental conditions. The local ePortal.

conditions (temperature, environmental conditions do not impact [Staff evaluation to be radiation and humidity) the capability of the components to EC 400578, Section 4.1.14 and included in SE Section anticipated during ELAP and perform their intended functions. EC 401069, discuss the 3.1.1.4]

severe accident for the environmental conditions during components (valves, an accident at the locations instrumentation, sensors, containing l&C components. The transmitters, indicators, staff's review indicated that the electronics, control devices, environmental qualification met and etc.) required for HCVS the order requirements.

venting including confirmation that the components are No follow-up questions.

capable of performing their functions during ELAP and severe accident conditions.

Phase 1 ISE 01 17 DCS Sections 4.1.5 and 4.1.33 of EC The NRC staff reviewed the Closed 400578 and EC 401069 discuss the information provided in the 6-Make available for NRC staff operations of the existing containment month updates and on the [Staff evaluation to be audit documentation of an isolation valves relied upon for the HCVS. ePortal. included in SE Section evaluation verifying the Appendix B of the DCS of EC 401069 3.1.2.1]

existing containment isolation describes the Primary Containment EC 400578, DCS Section 4.1.5 valves, relied upon for the Pressure Limit (PCPL), which is and 4.1.33 and EC 401069 HCVS, will open under the conservatively expected to be the discusses the valve/actuator maximum expected differential differential pressure during BDBEE and information for the PCIVs. The pressure during BDBEE and severe accident wetwell venting, being N RC staff verified the actuator severe accident wetwell less than the maximum valve differential can develop greater torque than venting. pressure limit. The PCPL is also less PCIV's unseating torque.

than the design pressure of the line containing the existing containment No follow-up questions.

isolation valve.

Phase 1 ISE 0118 The procedure for HCVS operation is The NRC staff reviewed the Closed FSG-15, "Hardened Containment Vent information provided in the 6-Make available for NRC staff Operation." month updates and on the [Staff evaluation to be audit guidelines and ePortal. included in SE Section procedures for HCVS The procedure is available for NRC 5.1]

operation. review on the ePortal. The guidelines and procedures for HCVS operation are complete and consistent with the guidance in NEI 13-02.

No follow-up questions.

Phase 2 ISE 01 1 EguiQment and Controls The NRG staff reviewed the Closed information provided in the 6-Licensee to evaluate the Plant instrumentation for SAWM that is month updates and on the [Staff evaluation to be SAWA [severe accident water qualified to RG 1.97 or equivalent is ePortal. included in SE Sections addition] equipment and considered qualified for the sustained 4.1.1.4 and 4.2.1.4]

controls, as well as ingress operating period without further EC 617659, along with and egress paths for the evaluation. The following plant calculations DRE17-0013 and expected severe accident instruments are qualified to RG 1.97: DRE16-0010 shows that conditions (temperature, DW Pressure 2(3)-1640-11 A(B) temperature and radiological humidity, radiation) for the Suppression Pool Level 2(3)-1640-10A(B) conditions should not inhibit sustained operating period. operator actions or SAWA Passive components that do not need to equipment and controls needed change state after initially establishing to initiate and operate the HCVS SAWA flow do not require evaluation during an ELAP with severe beyond the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, at which time accident conditions.

they are expected to be installed and ready for use to support SAWA/SAWM. No follow-up questions.

SAWA/SAWM flow instrument:

EC 617659 DCS section 4.1.36 describes details of SAWA flow meter. This flow meter will be attached to the SAWA manifold where flow rate will be measured and controlled.

SAWA/SAWM Pump:

SAWA/SAWM pump is a diesel driven and trailer mounted pump to be staged near the Cribhouse Intake. The pump is hydraulically driven with the hydraulic unit on the trailer and the pump head to be lowered in the Cribhouse Intake by the trailer mounted crane. Pump details are provided in EC 617659 DCS section 4.1.33 SAWA/SAWM Generator:

Two FLEX generators (800 KW each) are onsite. One generator is in robust FLEX Building A. The second generator is in FLEX Building C, which is not robust. For flooding scenario, these generators will be moved to the Turbine Deck at EL 561' as part of flood preparations. These generators will support SAWA/SAWM phases.

Ingress and Egress For locations outside the Reactor Building between 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> and 7 days when SAWA is being utilized, a quantitative evaluation (DRE16-0010) of expected dose rates has been performed per HCVS-WP-02 and found the dose rates at deployment locations including ingress/egress paths are acceptable.

DRE16-0010 is provided on ePortal for NRC Staff review.

Phase 2 ISE 01 2 Actions taken within the first 1.3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> The NRC staff reviewed the Closed (prior to start of core damage for information provided in the 6-Licensee to demonstrate how Dresden) from the start of the ELAP are month updates and on the [Staff evaluation to be instrumentation and equipment acceptable from an environmental and ePortal. included in SE Sections being used for SAWA and radiological perspective without further 4.1.1.4 and 4.2.1.4]

supporting equipment is evaluation. EC 617659, along with capable to perform for the calculations DRE17-0013 and sustained operating period Actions performed within the MCR are DRE16-0010, shows that under the expected acceptable for the entire period of temperature and radiological temperature and radiological Sustained Operation per HCVS-FAQ-06., conditions should not inhibit conditions Assumption 049-21. operator actions or SAWA equipment and controls needed For actions within the Reactor Building to initiate and operate the HCVS and between 1.3 and 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, a during an ELAP with severe quantitative evaluation of expected dose accident conditions.

rates has been performed (DRE 16-0010)

per HCVS-FAQ-12 and found the dose No follow-up questions.

rates at deployment locations including ingress/egress paths are acceptable. For locations outside the Reactor Building between 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> and 7 days when SAWA is being utilized, a quantitative evaluation (DRE16-0010) of expected dose rates has been performed per HCVS-WP-02 and found the dose rates at deployment locations, including ingress/egress paths are acceptable. DRE16-0010 is provided on ePortal for NRC staff review.

Phase 2 ISE 01 3 The wetwell vent has been designed and The NRC staff reviewed the Closed installed to meet NEI 13-02 Rev 1 information provided in the 6-Licensee to demonstrate that guidance, which will ensure that it is month updates and on the [Staff evaluation to be containment failure as a result adequately sized to prevent containment ePortal. included in SE Sections of overpressure can be overpressure under severe accident 4.1 and 4.2]

prevented without a drywell conditions. BWROG-TP-15-008 vent during severe accident demonstrates adding water to the conditions. The SAWA strategy will ensure that the reactor vessel within 8-hours of wetwell vent remains functional for the the onset of the event will limit the period of sustained operation. Dresden peak containment drywell will follow the guidance (flow rate and temperature significantly reducing timing) for SAWA/SAWM described in the possibility of containment BWROG-TP-15-008 and BWROG-TP failure due to temperature.

011. These documents have been posted Drywell pressure can be to the ePortal for NRC staff review. The controlled by venting the wetwell vent will be opened prior to suppression chamber through the exceeding the PCPL value as shown on suppression pool.

Fig. D of the Dresden EOP procedures.

Therefore, containment over BWROG-TP-011 demonstrates pressurization is prevented without the that starting water addition at a need for a drywell vent. high rate of flow and throttling after approximately 4-hours will DEOP-1 00 is provided on the ePortal for not increase the suppression pool NRC staff review. level to that which could block the suppression chamber HCVS.

The suppression pool will be provided with sufficient makeup to

maintain a heat sink for reactor decay heat, which will maintain containment within design limits.

The SAWM strategy will ensure that the wetwell vent remains functional for the period of sustained operation.

No follow-up questions.

Phase 2 ISE 01 4 From the combined Phases 1 and 2 OIP The NRC staff reviewed the Closed Attachment 2.1.C, Dresden parameters information provided in the 6-Licensee to demonstrate how are compared to the reference plant month updates and on the [Staff evaluation to be the plant is bounded by the parameters as shown below: ePortal. included in SE Section reference plant analysis that 4.2.1.1]

shows the SAWM strategy is Peach Bottom was used as the successful in making it unlikely Reference Plant reference plant. The staff that a drywell vent is needed. Torus freeboard volume is 525,000 concurs that it is unlikely the gallons, SAWA flow is 500 GPM [gallons suppression chamber HCVS per minute] at 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> followed by 100 could become blocked leading to GPM from 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />, a successful SAWA/SAWM strategy. Therefore, it is unlikely Dresden a drywell vent would be required Torus freeboard volume is 1,021,000 to maintain containment integrity.

gallons, SAWA flow is 421 GPM at 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> followed by 85 GPM from 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> No follow-up questions.

to 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br />.

The above parameters for Dresden compared to the reference plant that determine success of the SAWM strategy demonstrate that the reference plant values are bounding. Therefore, the SAWM strategy implemented at Dresden makes it unlikely that a drywell vent is needed to prevent containment overpressure related failure.

Phase 2 ISE 01 5 Dresden utilizes FSG-39, "FLEX The NRC staff reviewed the Closed Communication Options" to communicate information provided in the 6-Licensee to demonstrate that between the MCR and remote locations month updates and on the there is adequate such as the intake structure (Cribhouse ePortal.

communication between the Intake), FLEX pump in the RB basement [Staff evaluation to be main control room (MCR) and level and SAWA flow control manifold. The communication methods are included in SE Section the operator at the FLEX the same as accepted in Order 4.1]

manual valve during severe This communication method is the same EA-12-049.

accident conditions. as accepted in Order EA-12-049. These items will be powered and remain No follow-up questions.

powered using the same methods as evaluated under EA-12-049 for the period of sustained operation, which may be longer than identified forEA-12-049.

FSG-39 is provided on ePortal for NRC staff review.

Phase 2 ISE 01 6 The Design Consideration Summary of The NRC staff reviewed the Closed EC 617659, section 4.1.36 provides the information provided in the 6-Licensee to demonstrate the following details of the SAWA/SAWM flow month updates and on the [Staff evaluation to be SAWM flow instrumentation meter. ePortal. included in SE Sections qualification for the expected 4.1.1.3 and 4.2.1.3]

environmental conditions. For locations outside the Reactor Building EC 617659, Section 4.1.36 between 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> and 7 days when SAWA discusses the SAWM flow is being utilized, Dresden performed a instrumentation qualification. The quantitative evaluation of he expected NRC staff determined that the dose rates at deployment locations accuracy of the flow meter and including ingress/egress paths are the environmental qualifications acceptable. The selected instrument is related to the performance of the designed for the expected flow rate, flow meter meet the intent of temperature and pressure for SAWA over Order EA-13-109.

the period of sustained operation.

No follow-up questions.

SAWA Flow Instrument 80 to 2300 GPM, Oto 125 °F (Operating) and Oto 185 °F (Storage), 0 to 300 PSI Ex12ected SAWA Parameter Qualification Range 85 to 421 GPM, -6 to 94 °F, Oto 200 PSI

The new flow meter is an FRC model FTA500. The unit is powered by an internal lead acid battery which will power the flow meter for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> under normal expected operating conditions. Operating and storage temperatures of the flow meter are limited by the battery used.

Colder ambient temperatures reduce the life expectancy and capacity of the internal battery. In order to conserve battery power, the flow meter will only be turned on when determining the flow required during a SAWA event. As a backup, the flow meter may be powered by a 120/240 VAC source, which can be provided from the FLEX diesel generator or other small portable generator available as part of the existing FLEX equipment inventory. The flow meter uses a paddle wheel to determine flow and is, therefore, not *sensitive to the conductivity of the water. The flow meter is only used when changing the flow through the manifold and can be disconnected and brought to a warmer location such as a FLEX equipment deploymenUrefueling vehicle as a means to extend battery capacity when not required or powered from an external power source. The flow meter electronics including battery can be disconnected from and reconnected to the flow meter body without disruption of SAWA flow path. The body of the SAWA flow meter will remain at or near the process flow temperatures at or above 32°F due to the continuous SAWA flow. The SAWA flow meter is qualified for the expected environmental conditions that may exist over the period of Sustained Operation.

The instrument requires at least 10 ft. of 4" diameter hose upstream of the instrument for an accurate flow indication.

Therefore, the 10 ft. of 4" diameter hose will be installed between the SAWA manifold and the flow meter.

EC 617659, DCS is provided on ePortal for NEC staff review.

ML17349A926 *via e-mail OFFICE NRR/DLP/PBEB/PM NRR/DLP/PBMB/LA NRR/DLP/PBEB/BC NRR/DLP/PBEB/PM NAME RAuluck SLent TBrown RAuluck DATE 12/19/2017 12/18/2017 12/20/2017 12/20/2017