Text

Monticello Nuclear Generating Plant - Interim Staff Evaluation Related to Overall Integrated Plant in Response to Order EA-13-109,Severe Accident Capable Hardened Vents
	ML15082A167
Person / Time
Site:	Monticello
Issue date:	04/02/2015
From:	Halter M K; Japan Lessons-Learned Division
To:	Gardner P A; Northern States Power Co
	Norton C H, NRR/JLD, 415-7818
References
	EA-13-109, TAC MF4376
	Download: ML15082A167 (40)
	v • d • e

Mr. Peter A. Gardner Site Vice President UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 2, 2015 Northern States Power Company -Minnesota Monticello Nuclear Generating Plant 2807 West County Road 75 Monticello, Ml 55362-9637

SUBJECT:

MONTICELLO NUCLEAR GENERATING PLANT -INTERIM STAFF EVALUATION RELATING TO OVERALL INTEGRATED PLAN IN RESPONSE TO PHASE ONE OF ORDER EA-13-109 (SEVERE ACCIDENT CAPABLE HARDENED VENTS) (TAC NO. MF4376)

Dear Mr. Gardner:

By letter dated June 6, 2013, 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 Conditions" (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 13143A334). By letter dated June 30, 2014 (ADAMS Accession No. ML 14183A412), Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, submitted its Overall Integrated Plan (OIP) for the Monticello Nuclear Generating Plant (Monticello) in response to Phase 1 of Order EA-13-109. By letter dated December 16, 2014 (ADAMS Accession No. ML 14353A215), NSPM submitted its first six-month status report for Monticello in response to Order EA-13-109. Any changes to the compliance method will be reviewed as part of the ongoing audit process. NSPM's OIP for Monticello appears consistent with the guidance found in Nuclear Energy Institute 13-02, Revision 0, endorsed, in part, by the NRC's Japan Lessons-Learned Project Directorate (JLD) Interim Staff Guidance (ISG) JLD-ISG-2013-02, as an acceptable means for implementing the requirements of Phase 1 of Order EA-13-109. This conclusion is based on satisfactory resolution of the open items detailed in the enclosed Interim Staff Evaluation. This evaluation only addressed consistency with the guidance. Any plant modifications will need to be conducted in accordance with plant engineering change processes and consistent with the licensing basis.

P. Gardner If you have any questions, please contact Charles H. Norton, Project Manager, at 301-415-7818 or via e-mail at Charles.Norton@nrc.gov. Docket No. 50-263

Enclosure:

Interim Staff Evaluation cc w/encl: Distribution via Listserv Sincerely, Mandy K. Halter, Acting Chief Orders Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 INTERIM STAFF EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO ORDER EA-13-109 PHASE 1 MODIFYING LICENSES WITH REGARD TO RELIABLE HARDENED CONTAINMENT VENTS CAPABLE OF OPERATION UNDER SEVERE ACCIDENT CONDITIONS NORTHERN STATES POWER COMPANY -MINNESOTA MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263

1.0 INTRODUCTION

By letter dated June 6, 2013, the U.S. Nuclear Regulatory Commission (NRC or Commission) issued Order EA-13-109, "Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation under Severe Accident Conditions" [Reference 1]. The order requires licensees to implement its requirements in two phases. In Phase 1, licensees of boiling-water reactors (BWRs) with Mark I and Mark II containments shall design and install a venting system that provides venting capability from the wetwell during severe accident conditions. In Phase 2, licensees of BWRs with Mark I and Mark II containments shall design and install a venting system that provides venting capability from the drywell under severe accident conditions, or, alternatively, those licensees shall 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.1 The purpose of the NRC staff's review, as documented in this interim staff evaluation (ISE) is to provide an interim evaluation of the Overall Integrated Plan (OIP) for Phase 1 of Order EA-13-109. Phase 1 of Order EA-13-109 requires that BWRs with Mark I and Mark II containments shall design and install a severe accident capable hardened containment vent system (HCVS) that provides venting from the wetwell during severe accident conditions, using a vent path from the containment wetwell to remove decay heat, vent the 1 This ISE only addresses the licensee's plans for implementing Phase 1 of Order EA-13-109. While the licensee's OIP makes reference to Phase 2 issues, those issues are not being considered in this evaluation. Issues related to Phase 2 of Order EA-13-109 will be cor:isidered in a separate ISE at a later date. Enclosure 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 (ac) power (ELAP). By letter dated June 30, 2014 [Reference 2], Northern States Power Company, a Minnesota corporation (NSPM, the licensee), doing business as Xcel Energy, submitted its Overall Integrated (OIP) Plan for the Monticello Nuclear Generating Plant (MNGP, Monticello) in response to Phase 1 of Order EA-13-109 for compliance with Phase 1 of Order EA-13-109. The OIP describes the licensee's currently proposed modifications to systems, structures, and components, new and revised guidance, and strategies that it intends to implement in order to comply with the requirements of Phase 1 of Order EA-13-109.

2.0 REGULATORY EVALUATION

Following the events at the Fukushima Dai-ichi nuclear power plant on March 11, 2011, the NRG established a senior-level agency task force referred to as the Near-Term Task Force (NTTF). The NTTF was tasked with conducting a systematic and methodical review of the NRG regulations and processes and determining if the agency should make improvements to these programs in light of the events at Fukushima Dai-ichi. As a result of this review, the NTTF developed a set of recommendations, documented in SECY-11-0093, "Recommendations For Enhancing Reactor Safety in The 2151 Century-The Near-Term Task Force Review of Insights From The Fukushima Dai-lchi Accident," dated July 12, 2011 [Reference 3]. These recommendations were enhanced by the NRG staff following interactions with stakeholders. Documentation of the NRG staff's efforts is contained in the Commission's Staff Requirements Memorandum (SRM) for SECY-11-0124, "Recommended Actions to be Taken without Delay from the Near-Term Task Force Report," dated September 9, 2011 [Reference 4] and SECY-11-0137, "Prioritization of Recommended Actions to be Taken in Response to Fukushima Lessons Learned," dated October 3, 2011 [Reference 5]. As directed by the Commission's SRM for SECY-11-0093 [Reference 6], the NRG staff reviewed the NTTF recommendations within the context of the NRC's existing regulatory framework and considered the various regulatory vehicles available to the NRG to implement the recommendations. SECY-11-0124 and SECY-11-0137 established the NRG staff's prioritization of the recommendations based upon the potential safety enhancements. On February 17, 2012, the NRG staff provided SECY-12-0025, "Proposed Orders and Requests for Information in Response to Lessons Learned from Japan's March 11, 2011, Great Tohoku Earthquake and Tsunami" [Reference 7], to the Commission, including the proposed order to implement the installation of a reliable HCVS for Mark I and Mark II containments. As directed by SRM-SECY-12-0025 [Reference 8], the NRG staff issued Order EA-12-050, "Order Modifying Licenses with Regard to Reliable Hardened Containment Vents" [Reference 9], which required licensees to install a reliable HCVS for Mark I and Mark II containments. While developing the requirements for Order EA-12-050, the NRG acknowledged that questions remained about maintaining containment integrity and limiting the release of radioactive materials if the venting systems were used during severe accident conditions. The NRG staff presented options to address these issues for Commission consideration in SECY-12-0157, "Consideration of Additional Requirements for Containment Venting Systems for Boiling Water Reactors with Mark I and Mark II Containments" [Reference 1 O]. In the SRM for SECY-12-0157 [Reference 11], the Commission directed the staff to issue a modification to Order EA-12-050, requiring licensees with Mark I and Mark II containments to "upgrade or replace the reliable hardened vents required by Order EA-12-050 with a containment venting system designed and installed to remain functional during severe accident conditions." The NRC staff held a series of public meetings following issuance of SRM SECY-12-0157 to engage stakeholders on revising the order. Accordingly, by letter dated June 6, 2013, the NRC issued Order EA-13-109, "Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Performing under Severe Accident Conditions." Order EA-13-109, Attachment 2, requires that BWRs with Mark I and Mark II containments have a reliable, severe-accident capable HCVS. This requirement shall be implemented in two phases. In Phase 1, licensees of BWRs with Mark I and Mark II containments shall design and install a venting system that provides venting capability from the wetwell during severe accident conditions. Severe accident conditions include the elevated temperatures, pressures, radiation levels, and combustible gas concentrations, such as hydrogen and carbon monoxide, associated with accidents involving extensive core damage, including accidents involving a breach of the reactor vessel by molten core debris. In Phase 2, licensees of BWRs with Mark I and Mark II containments shall design and install a venting system that provides venting capability from the drywell under severe accident conditions, or, alternatively, those licensees shall 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. On November 12, 2013, the Nuclear Energy Institute (NEI) issued NEI 13-02, "Industry Guidance for Compliance with Order EA-13-109," Revision 0 [Reference 12] to provide guidance to assist nuclear power reactor licensees with the identification of measures needed to comply with the requirements of Phase 1 of the HCVS order. On November 14, 2013, the NRC staff issued Japan Lessons-Learned Project Directorate (JLD) interim staff guidance (ISG) JLD-ISG-2013-02, "Compliance with Order EA-13-109, 'Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Performing under Severe Accident Conditions"' [Reference 13], endorsing, in part, NEI 13-02, Revision 0, as an acceptable means of meeting the requirements of Phase 1 of Order EA-13-109, and published a notice of its availability in the Federal Register (FR) [78 FR 70356]. Licensees are free to propose alternate methods for complying with the requirements of Phase 1 of Order EA-13-109. By letter dated May 27, 2014 [Reference 14], the NRC notified all BWR Mark I and Mark II Licensees that the staff will be conducting audits of the implementation of Order EA-13-109. This letter described the audit process to be used by the staff in its review of the information contained in licensee's submittals in response to Phase 1 of Order EA-13-109.

3.0 TECHNICAL EVALUATION

MNGP is a single unit General Electric BWR with a Mark I primary containment system. MNGP is upgrading the existing HCVS to a reliable HCVS capable of operation under severe accident conditions to meet the requirements of Phase 1 of Order EA-13-109. The Existing HCVS is routed from a dedicated wetwell penetration through two containment isolation valves and a rupture disk to a release point three feet above the reactor building roof. The OIP describes upgrades to HCVS electrical power and pneumatic motive force systems. The 01 P considers the temperature and radiation effects to HCVS system operators during ELAP and severe accident conditions. In addition the OIP describes programmatic changes that include procedures, training, drills and maintenance. 3.1 GENERAL INTEGRATED PLAN ELEMENTS AND ASSUMPTIONS 3.1.1 Evaluation of Extreme External Hazards Extreme external hazards for MNGP were evaluated in the MNGP OIP in response to Order EA-12-049 (Mitigation Strategies) [Reference 15]. In the MNGP ISE relating to Mitigation Strategies [Reference 16], the NRC staff documented an analysis of NSPM's extreme external hazards evaluation. The following extreme external hazards screened in: Seismic, Flooding, Extreme Cold, Snow and Ice, High Wind, and High Temperature. No extreme external hazards screened out. Based on MNGP not excluding any external hazard from consideration, the NRC staff determined that NSPM appears to have identified the appropriate external hazards for consideration in the design of HVCS. 3.1.2 Assumptions On page 6 of the MNGP OIP, NSPM adopted a set of generic assumptions associated with Order EA-13-109 Phase 1 actions. The staff determined that the set of generic assumptions appear to establish a baseline for HCVS evaluation consistent with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable method to implement the requirements of Order EA-13-109. The NRC staff reviewed the MNGP plant-specific HCVS related assumptions: 1. Alternate Shutdown System Panel Rather than the main control room, NSPM will use the Alternate Shutdown System panel located in the Emergency Filtration (EFT} Building as the primary control station for operation and monitoring of the HCVS, as permitted by Order EA-13-109, Section 1.2.4. 2. Backup HCVS Operating Station If operation is not possible from the Alternate Shutdown System panel, the HCVS will be operated from the Turbine Building in the vicinity of Train B of the Alternate Nitrogen System. This location will be called the Backup HCVS Operating Station. 3. Initiation of Venting The vent will not be opened at a specific time. The HCVS will be initiated per plant procedural guidance. The staff determined that the plant specific assumptions for MNGP do not appear to create deviations from the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable method to implement the requirements of Order EA-13-109.

3.1.3 Compliance Timeline and Deviations Page 4 of the OIP states the following: Compliance will be attained with no known deviations to the schedule in Order EA-1 3-109 for each phase as follows:

Phase 1 (wetwell): by the startup from the second refueling outage that begins after June 30, 2014, or June 30, 2018, whichever comes first. This refueling outage is currently scheduled for completion in April 2017.

Phase 2: Later NSPM has identified one alternative from the guidance in JLD-ISG-2013-02 and NEI 13-02, which is described in the following paragraphs. HCVS Release Location NEI 13-02, Section 4.1.5.2.2 (Reference 11 [of the OIP]), states: The release point should be situated away from ventilation system intake and exhaust openings or other openings that may be used as natural circulation ventilation intake flow paths during a BDBEE (e.g., to prevent recirculation of the releases back into the buildings.) The HCVS discharge path is currently routed next to the Reactor Building plenum exhaust with the vent exhaust 3 ft. above the top of the Reactor Building plenum exhaust stack (see Figure 1 [of the OIP]). The vent exhaust is above the main plant structures. The vent is located greater than 100 ft. above ground level, providing an elevated release point that will not affect personnel staging any portable equipment needed for the Beyond Design Basis External Event (BDBEE).

Figure 1 [of the OIP]: HCVS Exhaust Vent Side View Reactor Building Roof Reactor Building ...__ Discharge Dampers '!::--Backdraft Dampers Reactor Building Plenum Exhaust fans Top View \ ==;ii ( \ ) I I ') The HCVS exhaust vent is not near the Reactor Building intake, control room intake, or the emergency response facilities, but is next to the Reactor Building plenum exhaust path. The Reactor Building plenum exhaust fans will be without a power source in a station blackout. There are two dampers after each Reactor Building plenum exhaust fan -a backdraft damper and discharge damper. The discharge damper will close on loss of power associated with the station blackout and the backdraft damper will close on loss of Reactor Building exhaust flow. Both dampers are designed to prevent reverse flow, and therefore, prevent HCVS gases from entering the Reactor Building via the plenum room. Safety related dampers also isolate the plenum room from the rest of the Reactor Building. The "T" at the top of the vent will also be removed and replaced with a straight exit with a weather cap. This change will direct the vented gases upward and away from the plant. Therefore, the existing HCVS vent configuration is an acceptable alternative to JLD-ISG-13-02 and NEI 13-02. If additional deviations are identified, then the deviations will be communicated in a future six-month status report following identification. MNGP's implementation schedule appears to comply with the requirements of Order EA-13-109. As far as the HCVS effluent release point is concerned, the licensee identified an alternative to the effluent release point described in the guidance provided by NEI 13-02, Section 4.1.5.2.2.

The alternative considers and addresses the underlying provisions of Order EA-13-109, Sections 1.1.3 and 1.2.12 which state: 1.1.3 The HCVS shall also be designed to account for radiological conditions that would impede personnel actions needed for event response. 1.2.12 The HCVS shall be designed to minimize the potential for hydrogen gas migration and ingress into the reactor building or other buildings. Therefore, MNGP's HCVS existing effluent release point location appears to be an acceptable alternative to the release point described in the guidance provided by NEI 13-02, Section 4.1.5.2.2. 3.2 BOUNDARY CONDITIONS FOR WETWELL VENT 3.2.1 Sequence of Events (SOE) Order EA-13-109, Sections 1.1.1, 1.1.2, and 1.1.3 state that: 1.1.1 The HCVS shall be designed to minimize the reliance on operator actions. 1.1.2 The HCVS shall be designed to minimize plant operators' exposure to occupational hazards, such as extreme heat stress, while operating the HCVS system. 1.1.3 The HCVS shall also be designed to account for radiological conditions that would impede personnel actions needed for event response. Page 9 of the OIP states the following: The operation of the HCVS will be designed to minimize the reliance on operator actions in response to hazards listed in Part 1 [of the OIP]. Immediate operator actions will be completed by plant personnel and will include the capability for remote-manual initiation. A list of the manual actions that will be performed by plant personnel to open the HCVS vent path can be found in Table 2-1 [of the OIP]. A HCVS Extended Loss of AC Power (ELAP) Failure Evaluation table, which shows alternate actions that can be performed, is included in Attachment 4 [of the OIP]. The NRC staff reviewed the Remote Manual Actions (Table 2-1 of the OIP) and concluded that these actions appear to consider minimizing the reliance on operator actions. The actions appear consistent with the types of actions described in the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. The NRC staff reviewed the Wetwell HCVS Failure Evaluation Table (Attachment 4 of the OIP) and determined the actions described appear to adequately address all the failure modes listed in the guidance provided by NEI 13-02, which include: loss of normal ac power, long term loss of batteries, loss of normal pneumatic supply, loss of alternate pneumatic supply, and solenoid operated valve (SOV) failure. The staff reviewed the three cases contained in the SOE timeline (Attachment 2 of the OIP) and determined that the three cases appropriately bound the conditions for which the HCVS is required. These cases include: successful FLEX implementation with no failure of reactor core isolation cooling (RCIC); late failure of RCIC leading to core damage; and failure of RCIC to inject at the start of the event. The timelines accurately reflect the progression of events as described in the MNPS Mitigation Strategies OIP [Reference 17], SECY-12-0157 [Reference 1 O], and State-of-the-Art Reactor Consequence Analyses (SOARCA) [Reference 18]. The NRC staff reviewed the licensee discussion of time constraints on page 10 of the OIP and confirmed that the time constraints identified appear to be appropriately derived from the time lines developed in Attachment 2 of the OIP, consistent with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02. The time constraints establish when the HCVS must be initiated and when supplemental compressed gas for motive power and supplemental electrical power (FLEX) must be supplied. The final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation and the HCVS nitrogen pneumatic system design including sizing and location are not available at this time; therefore, the NRC staff has not completed its review. The NRC staff reviewed the discussion of radiological and temperature constraints on page 1 O of the OIP. The licensee identified that accessibility evaluations are required for specific HCVS locations outside the main control room. Until these locations are finalized, the licensee cannot complete evaluations of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment; therefore, the staff has not completed its review. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. 3.2.2 Vent Characteristics 3.2.2.1 Vent Size and Basis Order EA-13-109, Section 1.2.1 states that: 1.2.1 The HCVS shall have the capacity to vent the steam/energy equivalent of one (1) percent of licensed/rated thermal power (unless a lower value is justified by analyses), and be able to restore and then maintain containment pressure below the primary containment design pressure and the primary containment pressure limit. Page 13 of the OIP states the following: The existing HCVS wetwell path is designed for venting steam/energy at a nominal capacity of 1 % or greater of 2004 MWt [megawatt thermal] thermal power at a pressure of 56 psig. This pressure is the lower of the containment design pressure and the PCPL value. The size of the wetwell portion of the HCVS (provided below in the "Vent Path and Discharge" response) provides adequate capacity to meet or exceed the Order criteria. The MNGP OIP describes a vent sized to meet or exceed one percent or greater current licensed thermal power. An analysis that demonstrates that the suppression pool and the HCVS together are able to absorb and reject decay heat, such that following a reactor shutdown from full power, containment pressure is restored and then maintained below the primary containment design pressure and the primary containment pressure limit is not available at this time; therefore, the staff has not completed its review. Open Item: Make available for NRC staff audit analyses demonstrating that HCVS has the capacity to vent the steam/energy equivalent of one percent of licensed/rated thermal power (unless a lower value is justified), and that the suppression pool and the HCVS together are able to absorb and reject decay heat, such that following a reactor shutdown from full power containment pressure is restored and then maintained below the primary containment design pressure and the primary containment pressure limit. 3.2.2.2 Vent Capacity Order EA-13-109, Section 1.2.1 states that: 1.2.1 The HCVS shall have the capacity to vent the steam/energy equivalent of one (1) percent of licensed/rated thermal power (unless a lower value is justified by analyses), and be able to restore and then maintain containment pressure below the primary containment design pressure and the primary containment pressure limit. Page 13 of the 01 P states the following: The 1 % value at MNGP assumes that the suppression pool pressure suppression capacity is sufficient to absorb the decay heat generated during the first 3 hours3.472222e-5 days 8.333333e-4 hours 4.960317e-6 weeks 1.1415e-6 months . The vent would then be able to prevent containment pressure from increasing above the containment design pressure. The duration of suppression pool decay heat absorption capability has been confirmed. The MNGP assumes that until decay heat is less than the one percent capacity of the proposed HCVS, the suppression pool must absorb the decay heat generated until the HCVS is able to restore and maintain primary containment pressure below the primary containment design pressure. Analyses confirming that HCVS has the capacity to vent the steam/energy equivalent

-10 -of one percent of licensed/rated thermal power (unless a lower value is justified), and that the suppression pool and the HCVS together are able to absorb and reject decay heat, such that following a reactor shutdown from full power containment pressure is restored and then maintained below the primary containment design pressure and the primary containment pressure limit are not available at this time; therefore, the staff has not completed its review. Open Item: Make available for NRC staff audit analyses demonstrating that HCVS has the capacity to vent the steam/energy equivalent of one percent of licensed/rated thermal power (unless a lower value is justified), and that the suppression pool and the HCVS together are able to absorb and reject decay heat, such that following a reactor shutdown from full power containment pressure is restored and then maintained below the primary containment design pressure and the primary containment pressure limit. 3.2.2.3 Vent Path and Discharge Order EA-13-109, Sections 1.1.4 and 1.2.2 state that: 1.1.4 The HCVS controls and indications shall be accessible and functional under a range of plant conditions, including severe accident conditions, extended loss of AC power, and inadequate containment cooling. 1.2.2 The HCVS shall discharge the effluent to a release point above main plant structures. Page 13 of the 01 P states the following: The existing HCVS vent connects to the wetwell through an eight inch dedicated penetration. Two air-operated valves (AOV) in series provide containment isolation. These valves are located in the torus room. The eight inch line then enters the HPCI [high-pressure coolant injection] room connecting to a rupture disc. The rupture disc will rupture at 44 to 50 psig. It can be ruptured by compressed nitrogen supplied via two solenoid operated valves, which pressurize the area between the outboard containment isolation valve and the rupture disc. Immediately upstream of the rupture disc, the vent line changes to a 10 inch pipe that exits the Reactor Building through the HPCI roof. The vent then travels up the side of the Reactor Building where the piping continues horizontally by approximately 60 ft. The vent piping then runs vertically beside the Reactor Building vent stack to an elevation 3 ft. above the highest structure on the Reactor Building roof. A layout of the MNGP buildings is provided in Figure 2 [of the OIP]. The HCVS discharge path is routed to a point above any adjacent structure. This discharge point is above the Reactor Building such that the release point will vent away from emergency ventilation system intake and exhaust openings, main control room location, location of HCVS portable equipment, access routes required following an ELAP and BDBEE, and emergency response facilities; however, these must be considered in conjunction with other design criteria (e.g.,

-11 -flow capacity) and pipe routing limitations, to the degree practical. As discussed in Part 1 [of the OIP], the HCVS discharge is in the vicinity of the Reactor Building plenum exhaust. The missile protection for the HCVS will follow the generic industry guidance on missile protection for HCVS (Open Item 1 [of the OIP]). The MNGP OIP describes the routing and discharge point of the HCVS that, pending resolution of open items, appear consistent with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. An evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment and the seismic and tornado missile final design criteria for the HCVS stack are not available at this time; therefore, the NRC staff has not completed its review. Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. Open Item: Make available for NRC staff audit the seismic and tornado missile final design criteria for the HCVS stack. 3.2.2.4 Power and Pneumatic Supply Sources Order EA-13-109, Sections 1.2.5 and 1.2.6 state that: 1.2.5 The HCVS shall, in addition to meeting the requirements of 1.2.4, be capable of manual operation (e.g., reach-rod with hand wheel or manual operation of pneumatic supply valves from a shielded location), which is accessible to plant operators during sustained operations. 1.2.6 The HCVS shall be capable of operating with dedicated and permanently installed equipment for at least 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months following the loss of normal power or loss of normal pneumatic supplies to air operated components during an extended loss of ac power. Page 15 of the OIP states the following: The electrical power supply required for operation of HCVS components will be supplied by a battery with sufficient capacity for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , after which the battery will be charged by a portable FLEX diesel generator. The following HCVS components will be electrically powered:

One Solenoid for each of the two containment isolation valves

Two Solenoids for opening the rupture disc

Valve position indication for containment isolation valves

HCVS radiation monitor

HCVS temperature monitor

-12 -NSPM has not completed the design of the HCVS power supply sources. NSPM will identify the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months power supply for the HCVS (Open Item 2 [of the OIP]). NSPM has not completed the dose evaluation for the FLEX portable equipment staging area. NSPM will determine the radiological conditions for the FLEX portable equipment staging areas (Open Item 3 [of the OIP]). Pneumatic supply is currently provided by the B Train of the Alternate Nitrogen System. The following HCVS components will be pneumatically powered:

Two containment isolation valves (AOVs)

Opening the rupture disc The B Train of the Alternate Nitrogen System is located in the Turbine Building. Train B of the Alternate Nitrogen System currently provides a safety related backup pneumatic supply to the following components:

T-ring seals for three Primary Containment & Atmospheric Control System purge and vent valves,

Three of the eight Safety Relief Valves.

Inboard Main Steam Isolation Valves.

HCVS isolation valves and rupture disc. The purpose of the Alternate Nitrogen System is to provide the pneumatic supply to the above components during accident scenarios when the non-safety related pneumatic supplies, Instrument Air and Instrument Nitrogen, may be unavailable. Nitrogen bottles will ensure the HCVS will be able to perform the following:

Open the rupture disc,

Open the first containment isolation valve once, and

Open the second containment isolation valve 8 times in the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . 1. The HCVS flow path valves are AOVs with air-to-open and spring-to-shut. Opening the valves requires energizing a solenoid operated valve (SOV) and providing motive air/gas. The detailed design will provide a permanently installed power source and motive air/gas supply adequate for the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The FLEX diesel generator will provide power for HCVS after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . NSPM will identify the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months power supply for the HCVS (Open Item 2 [of the OIP]). 2. An assessment of temperature and radiological conditions will be performed to ensure that operating personnel can safely access and operate controls based on time constraints listed in Attachment 2 [of the OIP]. NSPM will evaluate the Alternate Shutdown System panel and Backup HCVS Operation Station locations for accessibility, habitability, staffing sufficiency, associated pathways from the control room and communication capability with vent-use decision makers (Open Item 4 [of the OIP]).

-13 -3. All permanently installed HCVS equipment, including any connections required to supplement the HCVS operation during an ELAP (i.e., electric power, nitrogen) will be located in areas reasonably protected from defined hazards listed in Part 1 of this report. 4. All valves required to open the flow path will be designed for remote manual operation following an ELAP, such that the primary means of valve manipulation does not rely on use of a hand wheel, reach-rod or similar means that requires close proximity to the valve (Reference 16 [of the OIP]). Any supplemental connections will be pre-engineered to minimize manpower resources and address environmental concerns. Required portable equipment will be reasonably protected from screened in hazards listed in Part 1 of this [the licensee's] OIP. 5. Access to the locations described above will not require temporary ladders or scaffolding. 6. Following the initial 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period, additional motive force will be supplied from the replenishment of the alternate nitrogen system bottles. The alternate nitrogen system bottles are located in the Turbine Building and shielded from the HCVS vent by a 4 ft. concrete wall. Additional bottles will be brought in as needed. The MNGP OIP describes system features such as a dedicated battery and pneumatic supply that, pending resolution of open items, appear to make the system reliable. Specific design details not available at this time include: the final sizing evaluations for HCVS pneumatic supply, the final sizing for HCVS battery/battery charger including documentation of incorporating HCVS electrical sources into the FLEX DG loading calculations, and documentation of an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment; therefore, the staff has not completed its review. Open Item: Make available for NRC staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. 3.2.2.5 Location of Control Panels Order EA-13-109, Sections 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.2.4, and 1.2.5 state that: 1.1.1 The HCVS shall be designed to minimize the reliance on operator actions.

-14 -1.1.2 The HCVS shall be designed to minimize plant operators' exposure to occupational hazards, such as extreme heat stress, while operating the HCVS system. 1.1.3 The HCVS shall also be designed to account for radiological conditions that would impede personnel actions needed for event response. 1.1.4 The HCVS controls and indications shall be accessible and functional under a range of plant conditions, including severe accident conditions, extended loss of AC power, and inadequate containment cooling. 1.2.4 The HCVS shall be designed to be manually operated during sustained operations from a control panel located in the main control room or a remote but readily accessible location. 1.2.5 The HCVS shall, in addition to meeting the requirements of 1.2.4, be capable of manual operation (e.g., reach-rod with hand wheel or manual operation of pneumatic supply valves from a shielded location), which is accessible to plant operators during sustained operations. Page 16 of the OIP states the following: The HCVS design allows initiating, operating and monitoring HCVS from the Alternate Shutdown System panel. If the primary Alternate Shutdown System panel is inaccessible during an ELAP, then the Backup HCVS Operating Station will be used to initiate and operate the HCVS. NSPM will evaluate the Alternate Shutdown System panel and Backup HCVS Operation Station locations for accessibility, habitability, staffing sufficiency, associated pathways from the control room, and communication capability with vent-use decision makers (Open Item 4 [of the OIP]). The MNGP describes two HCVS control locations. Design details not available at this time include: descriptions of local conditions (temperature, radiation and humidity) anticipated during ELAP and severe accident for the components (valves, instrumentation, sensors, transmitters, indicators, electronics, control devices, etc.) required for HCVS venting including confirmation that the components are capable of performing their functions during ELAP and severe accident conditions, an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment [licensee identified], and documentation that demonstrates adequate communication between the remote HCVS operation locations and HCVS decision makers during ELAP and severe accident conditions. Open Item: Make available for NRC staff audit the descriptions of local conditions (temperature, radiation and humidity) anticipated during ELAP and severe accident for the components (valves, instrumentation, sensors, transmitters, indicators, electronics, control devices, etc.) required for HCVS venting including confirmation that the components are capable of performing their functions during ELAP and severe accident conditions.

-15 -Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. Open Item: Make available for NRC staff audit documentation that demonstrates adequate communication between the remote HCVS operation locations and HCVS decision makers during ELAP and severe accident conditions. 3.2.2.6 Hydrogen Order EA-13-109, Sections 1.2.10, 1.2.11, and 1.2.12 state that: 1.2.10 The HCVS shall be designed to withstand and remain functional during severe accident conditions, including containment pressure, temperature, and radiation while venting steam, hydrogen, and other non-condensable gases and aerosols. The design is not required to exceed the current capability of the limiting containment components. 1.2.11 The HCVS shall be designed and operated to ensure the flammability limits of gases passing through the system are not reached; otherwise, the system shall be designed to withstand dynamic loading resulting from hydrogen deflagration and detonation. 1.2.12 The HCVS shall be designed to minimize the potential for hydrogen gas migration and ingress into the reactor building or other buildings. Page 16 of the OIP states the following: As is required by Order EA-13-109, Section 1.2.11, the HCVS must be designed such that it is able to either provide assurance that oxygen cannot enter and mix with flammable gas in the HCVS (so as to form a combustible gas mixture), or it must be able to accommodate the dynamic loading resulting from a combustible gas detonation. Several configurations are available which will support the former (e.g., purge, mechanical isolation from outside air, etc.) or the latter (design of potentially affected portions of the system to withstand a detonation relative to pipe stress and support structures). The hydrogen control method has not been determined. NSPM will determine the approach or combination of approaches to control hydrogen (Open Item 5 [of the OIP]). A description of the final design for hydrogen control is not available at this time, including a description of the final design of the HCVS to address hydrogen detonation and deflagration (licensee identified) and a description of the strategies for hydrogen control that minimizes the potential for hydrogen gas migration and ingress into the reactor building or other buildings; therefore, the staff has not completed its review. Open Item: Provide a description of the final design of the HCVS to address hydrogen detonation and deflagration.

-16 -Open Item: Provide a description of the strategies for hydrogen control that minimizes the potential for hydrogen gas migration and ingress into the reactor building or other buildings. 3.2.2.7 Unintended Cross Flow of Vented Fluids Order EA-13-109, Sections 1.2.3 and 1.2.12 state that: 1.2.3 The HCVS shall include design features to minimize unintended cross flow of vented fluids within a unit and between units on the site. 1.2.12 The HCVS shall be designed to minimize the potential for hydrogen gas migration and ingress into the reactor building or other buildings. Page 16 of the OIP states the following: The HCVS piping does not interface with any other system piping or ductwork, except for Alternate Nitrogen System instrument lines. Therefore, cross flow is not a concern for MNGP. The MNGP OIP describes a HCVS that does not interface with other systems except the Alternate Nitrogen System which is used to breach the rupture disk. Part 1 of the OIP describes an alternative to the guidance provided in NEI 13-02 that precludes back flow from the HCVS release point through the reactor building ventilation exhaust plenum, as discussed in section 3.1.3 of this ISE. 3.2.2.8 Prevention of Inadvertent Actuation Order EA-13-109, Section 1.2.7 states that: 1.2.7 The HCVS shall include means to prevent inadvertent actuation. Page 16 of the OIP states the following: The HCVS will be designed to provide features to prevent inadvertent actuation due to a design error, equipment malfunction, or operator error such that any credited containment accident pressure (CAP) that would provide net positive suction head to the emergency core cooling system (ECCS) pumps will be available (inclusive of a design basis loss-of-coolant accident (DBLOCA)). However, the ECCS pumps will not have normal power available, because of the starting boundary conditions of an ELAP. EOPs [emergency operating procedures] provide supplementary instructions to point out that reducing primary containment pressure will affect Net Positive Suction Head (NPSH) margin. This administrative control, along with key lock switches on the Alternate Shutdown System (ASDS) panel will prevent inadvertent vent opening.

-17 -The features that currently prevent inadvertent actuation are key lock switches on the Alternate Shutdown System (ASDS) panel. Controls that open the vent at the Backup HCVS Operating Station, which will only be used if vent operation cannot be performed from the Alternate Shutdown System panel, will be locked to prevent inadvertent actuation. The MNGP OIP describes methods to prevent inadvertent initiation that including procedure controls, and keylock switches. This appears to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. 3.2.2.9 Component Qualifications Order EA-13-109, Section 2.1 states that: 2.1 The HCVS vent path up to and including the second containment isolation barrier shall be designed consistent with the design basis of the plant. Items in this path include piping, piping supports, containment isolation valves, containment isolation valve actuators and containment isolation valve position indication components. Page 17 of the OIP states the following: The HCVS components downstream of the second containment isolation valve up to the HPCI room roof are routed in seismically qualified structures. The piping outside safety related structures is designed to Class II and supported to meet Class I seismic requirements. HCVS components that directly interface with the pressure boundary are considered safety related, as the existing system is safety related. Likewise, any electrical or controls component which interfaces with Class 1 E power sources will be considered safety related up to and including appropriate isolation devices such as fuses or breakers, as their failure could adversely impact containment isolation and/or a safety-related power source. The remaining components will be considered Augmented Quality. Newly installed piping and valves will be seismically qualified to handle the forces associated with the safe shutdown earthquake (SSE) back to their isolation boundaries. Electrical and controls components will be seismically qualified and will include the ability to handle harsh environmental conditions (although they will not be considered part of the site Environmental Qualification (EQ) program). HCVS instrumentation performance (e.g., accuracy and precision) need not exceed that of similar plant installed equipment. Additionally, the radiation monitoring instrumentation accuracy and range will be sufficient to confirm flow of radionuclides through the HCVS. The HCVS instruments, including valve position indication, process instrumentation, radiation monitoring, and support system monitoring, will be

-18 -qualified by using one or more of the three methods described in the ISG, which includes: 1. Purchase of instruments and supporting components with known operating principles from manufacturers with commercial quality assurance programs (e.g., IS09001) where the procurement specifications include the applicable seismic requirements, design requirements, and applicable testing. 2. Demonstration of seismic reliability via methods that predict performance described in IEEE [Institute of Electrical and Electronic Engineers] 344-2004 (Reference 27). 3. Demonstration that instrumentation is substantially similar to the design of instrumentation previously qualified. Table 2-2 [of the OIP]: Instrumentation Qualification Methods Instrument Qualification Method* HCVS Process Temperature IS09001 I IEEE 344-2004 I Demonstration HCVS Process Radiation Monitor IS09001 I IEEE 344-2004 I Demonstration HCVS Process Valve Position IS09001 I IEEE 344-2004 I Demonstration HCVS Pneumatic Supply Pressure IS09001 I IEEE 344-2004 I Demonstration HCVS Electrical Power Supply IS09001 I IEEE 344-2004 I Availability Demonstration *Note: NSPM will determine the Qualification Method for HCVS Instrumentation (Open Item 6 [of the OIP]). The specific qualification method used for each required HCVS instrument will be reported in future six-month status reports. The MNGS OIP describes component qualification methods that, pending resolution of open items, appear to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Specific details not available at this time include: information regarding the qualification methods of existing instrumentation, which will be used by operators to make containment venting decisions, descriptions of local conditions (temperature, radiation and humidity) anticipated during ELAP and severe accident for the components (valves, instrumentation, sensors, transmitters, indicators, electronics, control devices, etc.) required for HCVS venting including confirmation that the components are capable of performing their functions during ELAP and severe accident conditions, and design details that confirm existing containment isolation valves, relied upon for the HCVS, will open under the maximum expected differential pressure during a BDBEE and severe accident wetwell venting; therefore, the NRC staff has not completed its review.

-19 -Open Item: Make available for NRC staff audit descriptions of all instrumentation and controls (existing and planned) necessary to implement this order including qualification methods. Open Item: Make available for NRC staff audit the descriptions of local conditions (temperature, radiation and humidity) anticipated during ELAP and severe accident for the components (valves, instrumentation, sensors, transmitters, indicators, electronics, control devices, etc.) required for HCVS venting including confirmation that the components are capable of performing their functions during ELAP and severe accident conditions. Open Item: Make available for NRC staff audit documentation of an evaluation verifying the existing containment isolation valves, relied upon for the HCVS, will open under the maximum expected differential pressure during BDBEE and severe accident wetwell venting. 3.2.2.10 Monitoring of HCVS Order EA-13-109, Sections 1.1.4, 1.2.8, and 1.2.9 state that: 1.1 .4 The HCVS controls and indications shall be accessible and functional under a range of plant conditions, including severe accident conditions, extended loss of AC power, and inadequate containment cooling. 1.2.8 The HCVS shall include means to monitor the status of the vent system (e.g., valve position indication) from the control panel required by 1.2.4. The monitoring system shall be designed for sustained operation during an extended loss of AC power. 1.2.9 The HCVS shall include a means to monitor the effluent discharge for radioactivity that may be released from operation of the HCVS. The monitoring system shall provide indication from the control panel required by 1.2.4 and shall be designed for sustained operation during an extended loss of AC power. Page 18 of the OIP states the following: The MNGP wetwell HCVS will be capable of being manually operated during sustained operations from the Alternate Shutdown System panel and will meet the requirements of Order EA-1 3-109 element 1.2.4. To meet the intent for a secondary control location of Section 1.2.5 of the Order, a readily accessible Backup HCVS Operating Station in the Turbine Building will also be incorporated into the HCVS design as described in NEI 13-02 Section 4.2.2.1.2.1. The controls at the Backup HCVS Operating Station and Alternate Shutdown System panel locations will be accessible and functional under a range of plant conditions, including severe accident conditions with due consideration to source term and dose impact on operator exposure, ELAP, and inadequate containment cooling. NSPM will evaluate the Alternate Shutdown System panel and Backup HCVS Operation Station locations for accessibility, habitability, staffing

-20 -sufficiency, associated pathways from the control room and communication capability with vent-use decision makers (Open Item 4 [of the OIP]). The wetwell HCVS will include means to monitor the HCVS at the Alternate Shutdown System panel. The wetwell HCVS will also include indications for temperature and effluent radiation levels (see Table 2-3 [of the OIP] for details). Other important information on the status of supporting systems, such as power source status and pneumatic supply pressure will be available locally by the battery charger (power source status) and in the Turbine Building (pneumatic supply pressure). NSPM will evaluate the HCVS battery charger location for accessibility, habitability, staffing sufficiency, associated pathways from the control room and communication capability with vent-use decision makers (Open Item 8 [of the OIP]). Monitoring of the power source and the pneumatic supply pressure will be performed periodically, based on plant procedures. The wetwell HCVS includes existing containment pressure and wetwell level indication at the Alternate Shutdown System panel to monitor vent operation. Table 2-3 [of the OIP] summarizes the existing and planned instrumentation. The MNGP OIP describes HCVS monitoring and control that, pending resolution of open items, appears to be consistent with the guidance provided in NEI 13-02, endorsed, in part, by ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Descriptions of the environmental and radiological effects on HCVS controls and indications, and an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment are not available at this time; therefore, the staff has not completed its review. Open Item: Make available for NRC staff audit the descriptions of local conditions (temperature, radiation and humidity) anticipated during ELAP and severe accident for the components (valves, instrumentation, sensors, transmitters, indicators, electronics, control devices, etc.) required for HCVS venting including confirmation that the components are capable of performing their functions during ELAP and severe accident conditions. Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. 3.2.2.11 Component Reliable and Rugged Performance Order EA-13-109, Section 2.2 states that: 2.2 All other HCVS components shall be designed for reliable and rugged performance that is capable of ensuring HCVS functionality following a seismic event. These items include electrical power supply, valve actuator pneumatic supply and instrumentation (local and remote) components.

-21 -Page 19 of the OIP states the following: The HCVS downstream of the second containment isolation valve, including piping and supports has been designed/analyzed to conform to the requirements consistent with the applicable design codes for the plant and to ensure functionality following a design basis earthquake. The HCVS electrical power supply, valve actuator pneumatic supply, and instrumentation (local and remote) components will be designed/analyzed to conform to the requirements consistent with the applicable design codes for the plant and to ensure functionality following a design basis earthquake. Additional modifications required to meet the Order will be reliably functional at the temperature, pressure, and radiation levels consistent with the vent pipe conditions for sustained operations. The instrumentation/power supplies/cables/connections (components) will be qualified for temperature, pressure, radiation level, and total integrated dose radiation for the effluent vent pipe. Conduit design will be installed to Seismic Class 1 criteria. Both existing and new barriers will be used to provide a level of protection from missiles when equipment is located outside of seismically qualified structures. Augmented quality requirements will be applied to the components installed in response to this Order. If the instruments are purchased as commercial-grade equipment, they will be qualified to operate under severe accident environment as required by NRC Order EA-13-109 and the guidance of NEI 13-02. For the instruments required after a potential seismic event, the following methods will be used to verify that the design and installation is reliable I rugged and thus capable of ensuring HCVS functionality following a seismic event. Applicable instruments will be rated by the manufacturer (or otherwise tested) for seismic impact at levels commensurate with those of postulated severe accident event conditions in the area of instrument component use using one or more of the following methods:

demonstration of seismic motion will be consistent with that of existing design basis loads at the installed location;

substantial history of operational reliability in environments with significant vibration with a design envelope inclusive of the effects of seismic motion imparted to the instruments proposed at the location;

adequacy of seismic design and installation is demonstrated based on the guidance in Sections 7, 8, 9, and 10 of IEEE Standard 344-2004, IEEE Recommended Practice for Seismic Qualification of Class 1 E Equipment for Nuclear Power Generating Stations, or a substantially similar industrial standard;

demonstration that proposed devices are substantially similar in design to models that have been previously tested for seismic effects in excess of the

-22 -plant design basis at the location where the instrument is to be installed levels and frequency ranges); or

seismic qualification using seismic motion consistent with that of existing design basis loading at the installation location. The MNGP OIP provides descriptions for component reliable and rugged performance that appear to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. 3.2.3 Beyond Design Basis External Event Venting 3.2.3.1 First 24-Hour Coping Order EA-13-109, Section 1.2.6 states that: 1.2.6 The HCVS shall be capable of operating with dedicated and permanently installed equipment for at least 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months following the loss of normal power or loss of normal pneumatic supplies to air operated components during an extended loss of AC power. Page 21 of the OIP states the following: The operation of the HCVS will be designed to minimize the reliance on operator actions for response to an ELAP and BDBEE hazards identified in Part 1 of this OIP. Immediate operator actions will be completed by Operators from the HCVS control stations and include remote-manual initiation. The operator actions that will be required to open a vent path are described in Table 2-1 [of the OIP]. Remote-manual is defined in this report as a non-automatic power operation of a component and does not require the operator to be at or in close proximity to the component. No other operator actions will be required to initiate venting under the guiding procedural protocol. The HCVS has been designed to allow initiation, control, and monitoring of venting from the Alternate Shutdown System panel. NSPM will evaluate the Alternate Shutdown System panel location for accessibility, habitability, staffing sufficiency, associated pathways from the control room and communication capability with vent-use decision makers (Open Item 4). Alternate Shutdown System panel is located in a Class I structure, and therefore, is protected from the hazards assumed in Part 1 of this report [the OIP]. Permanently installed power and motive air/gas capability will be available to support operation and monitoring of the HCVS for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . Permanently installed equipment will supply nitrogen and power to HCVS for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

-23 -System control: i. Active: HCVS valves are operated in accordance with EOPs/AOPs to control containment pressure. The HCVS will be designed for at least 8 open/close cycles under ELAP conditions over the first 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months following an ELAP. Controlled venting will be permitted in the revised EPGs and associated implementing EOPs. ii. Passive: Inadvertent actuation protection is provided by key lock switches on the Alternate Shutdown System (ASDS) panel .. [sic]

A rupture disc is currently provided in the HCVS vent line downstream of the containment isolation valves. The rupture disc will be designed such that it can be intentionally breached from the Alternate Shutdown System panel or the Backup HCVS Operating Station, as directed by applicable procedures. The containment isolation valves must be opened to permit vent flow.

HCVS key lock switches located in the Alternate Shutdown System panel.

Controls at the Backup Operating Station in the Turbine Building will be locked. The MNGP OIP describes a first 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months BDBEE coping strategy that, pending resolution of open items, appears to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. The final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation and the final nitrogen pneumatic system design including sizing and location are not available at this time; therefore, the staff has not completed its review. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. 3.2.3.2 Greater Than 24-Hour Coping Order EA-13-109, Section 1.2.4 states that: 1.2.4 The HCVS shall be designed to be manually operated during sustained operations from a control panel located in the main control room or a remote but readily accessible location. Page 22 of the OIP states the following: After 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , available personnel will be able to connect supplemental motive air/gas to the HCVS. Connections for supplementing electrical power and motive

-24 -air/gas required for HCVS will be located in accessible areas with reasonable protection per NEI 12-06 and minimize personnel exposure to adverse conditions for HCVS initiation and operation. Connections will be pre-engineered quick disconnects to minimize manpower resources. A FLEX diesel generator will be used to ensure HCVS control power after 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The response to NRC EA-12-049 will demonstrate the capability for FLEX efforts to maintain the power source. These actions will provide long term support for HCVS operation for the period beyond 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to 7 days (sustained operation time period) because on-site and off-site personnel and resources will have access to provide needed action and supplies. The MNGP OIP describes a greater than 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months BDBEE coping strategy that, pending resolution of open items, appears to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. The final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation and the final nitrogen pneumatic system design including sizing and location are not available at this time; therefore, the staff has not completed its review. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. 3.2.4 Severe Accident Event Venting 3.2.4.1 First 24 Hour Coping Order EA-13-109, Section 1.2.6 states that: 1.2.6 The HCVS shall be capable of operating with dedicated and permanently installed equipment for at least 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months following the loss of normal power or loss of normal pneumatic supplies to air operated components during an extended loss of AC power. Page 24 of the OIP states the following: The operation of the HCVS will be designed to minimize the reliance on operator actions for response to an ELAP and severe accident events. Severe accident event assumes that specific core cooling actions from the FLEX strategies identified in the response to Order EA-12-049 were not successfully initiated. Access to the Reactor Building will be restricted as determined by the Reactor Pressure Vessel (RPV) water level and core damage conditions. Immediate actions will be completed by Operators at the Alternate Shutdown System panel

-25 -or in the Turbine Building via the Backup HCVS Operating Station, and will include remote-manual actions at the Train B Alternate Nitrogen System. The operator actions that will be required to open a vent path were previously listed in the BDBEE Venting Part 2 section of this report in Table 2-1 [of the OIP]. Permanently installed power and motive air/gas capability will be available to support operation and monitoring of the HCVS for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . Specifics are the same as for BDBEE Venting Part 2. System control: i. Active: Same as for BDBEE Venting Part 2. ii. Passive: Same as for BDBEE Venting Part 2. The MNGP OIP describes a first 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months severe accident coping strategy that, pending resolution of open items, appears to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Specific details not available at this time include: the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation, the final nitrogen pneumatic system design including sizing and location, and an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment; therefore, the NRC staff has not completed its review. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. 3.2.4.2 Greater Than 24 Hour Coping Order EA-13-109, Section 1.2.4, states that: 1.2.4 The HCVS shall be designed to be manually operated during sustained operations from a control panel located in the main control room or a remote but readily accessible location. 1.2.8 The HCVS shall include means to monitor the status of the vent system (e.g., valve position indication) from control panel required by 1.2.4. The monitoring system shall be designed for sustained operation during an extended loss of AC power.

-26 -Page 24 of the OIP states the following: Specifics are the same as for BDBEE Venting Part 2. These actions will provide long term support for HCVS operation for the period beyond 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to 7 days (sustained operation time period) because on-site and off-site personnel and resources will have access to provide needed action and supplies. The MNGP OIP describes a greater than 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months severe accident coping strategy that, pending resolution of open items, appears to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Specific details not available at this time include: the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation; the final nitrogen pneumatic system design including sizing and location; and an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment (licensee identified); therefore, the NRC staff has not completed its review. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. 3.2.5 Support Equipment Functions 3.2.5.1 BDBEE Order EA-13-109, Sections 1.2.8 and 1.2.9, state that: 1.2.8 The HCVS shall include means to monitor the status of the vent system (e.g., valve position indication) from control panel required by 1.2.4. The monitoring system shall be designed for sustained operation during an extended loss of AC power. 1.2.9 The HCVS shall include a means to monitor the effluent discharge for radioactivity that may be released from operation of the HCVS. The monitoring system shall provide indication from the control panel required by 1.2.4 and shall be designed for sustained operation during an extended loss of AC power.

-27 -Page 26 of the OIP states the following: Containment integrity is initially maintained by permanently installed equipment. All containment venting functions will be performed from the Alternate Shutdown System panel or the Backup HCVS Operating Station in the Turbine Building. Venting will require support from DC [direct current] power as well as the Alternate Nitrogen System. Before station batteries are depleted, a portable FLEX diesel generator, as detailed in the response to Order EA-12-049, will be credited to charge the station batteries and maintain DC bus voltage. The MNGP OIP describes BDBEE supporting equipment functions that, pending resolution of open items, appear to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Specific details not available at this time include the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation and the final nitrogen pneumatic system design including sizing and location; therefore, the NRC staff has not completed its review. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC Staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. 3.2.5.2 Severe Accident Venting Order EA-13-109, Sections 1.2.8 and 1.2.9, state that: 1.2.8 The HCVS shall include means to monitor the status of the vent system (e.g., valve position indication) from control panel required by 1.2.4. The monitoring system shall be designed for sustained operation during an extended loss of AC power. 1.2.9 The HCVS shall include a means to monitor the effluent discharge for radioactivity that may be released from operation of the HCVS. The monitoring system shall provide indication from the control panel required by 1.2.4 and shall be designed for sustained operation during an extended loss of AC power. Page 26 of the OIP states the following: The same support functions that are used in the BDBEE scenario would be used for severe accident venting. The MNGP OIP describes support equipment functions for severe accident venting that, pending resolution of open items, appear to be in accordance with the guidance found in NEI

-28 -13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Specific details not available at this time include: the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation, the final nitrogen pneumatic system design including sizing and location, and an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment (licensee identified); therefore, the NRC staff has not completed its review. Open Item: Make available for NRC staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRC staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. Open Item: Make available for NRC staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. 3.2.6 Venting Portable Equipment Deployment Order EA-13-109, Section 3.1, states that: 3.1 The licensee shall develop, implement, and maintain procedures necessary for the safe operation of the HCVS. Procedures shall be established for system operations when normal and backup power is available, and during an extended loss of AC power. Page 27 of the OIP states the following: Deployment pathways for compliance with Order EA-12-049 are acceptable without further evaluation needed except in areas around the Reactor Building or in the vicinity of the HCVS piping. Deployment in the areas around the Reactor Building or in the vicinity of the HCVS piping will allow access, operation and replenishment of consumables with the consideration that there is potential Reactor Core Damage and HCVS operation. The MNGP OIP describes supporting equipment deployment functions that, pending resolution of open items, appear to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Specific details not available at this time include: the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation, the final nitrogen pneumatic system design including sizing and location, and an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment; therefore, the NRC staff has not completed its review.

-29 -Open Item: Make available for NRG staff audit the final sizing evaluation for HCVS batteries/battery charger including incorporation into FLEX DG loading calculation. Open Item: Make available for NRG staff audit documentation of the HCVS nitrogen pneumatic system design including sizing and location. Open Item: Make available for NRG staff audit an evaluation of temperature and radiological conditions to ensure that operating personnel can safely access and operate controls and support equipment. Summary, Section 3.2: The licensee's approach to Boundary Conditions for Wetwell Vent, if implemented, as described in Section 3.2, and assuming acceptable resolution of any open items identified here or as a result of licensee alterations to their proposed plans, appears to be consistent with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. 3.3 BOUNDARY CONDITIONS FOR DRYWELL VENT Summary, Section 3.3: The Drywell Vent will be evaluated during Phase 2 of Order EA-13-109. The NRG staff will provide the ISG for Phase 2 by April 30, 2015. Licensees will submit an updated OIP to address Phase 2 of Order EA-13-109 by December 31, 2015. 3.4 PROGRAMMATIC CONTROLS, TRAINING, DRILLS AND MAINTENANCE 3.4.1 Programmatic Controls Order EA-13-109, Sections 3.1and3.2, state that: 3.1 The licensee shall develop, implement, and maintain procedures necessary for the safe operation of the HCVS. Procedures shall be established for system operations when normal and backup power is available, and during an extended loss of AC power. 3.2 The licensee shall train appropriate personnel in the use of the HCVS. The training curricula shall include system operations when normal and backup power is available, and during an extended loss of AC power. Page 30 of the OIP states the following: Program Controls: The HCVS venting actions will include:

Site procedures and programs will be developed in accordance with NEI 13-02 to address use and storage of portable equipment relative to the

-30 -Severe Accident defined in NRC Order EA-13-109 and the hazards applicable to the site per Part 1 of this OIP.

Routes for transporting portable equipment from storage location(s) to deployment areas will be developed as the response details are identified and finalized. The identified paths and deployment areas will be accessible during all modes of operation and during Severe Accidents. Procedures: Procedures will be established for system operations when normal and backup power is available, and during ELAP conditions. The HCVS procedures will be developed and implemented following the plants process for initiating or revising procedures and contain the following details:

appropriate conditions and criteria for use of the HCVS

when and how to place the HCVS in operation,

the location of system components,

instrumentation availabl_e,

normal and backup power supplies,

directions for sustained operation, including the storage location of portable equipment,

training on operating the portable equipment, and

testing of portable equipment EOPs provide supplementary instructions to point out that reducing primary containment pressure will affect Net Positive Suction Head (NPSH) margin. NSPM will establish provisions for out-of-service requirements of the HCVS and compensatory measures. The following provisions will be documented in the Technical Requirements Manual: The provisions for out-of-service requirements for HCVS functionality are applicable in Modes 1 , 2 and 3.

If for up to 90 consecutive days, the primary or alternate means of HCVS operation are nonfunctional, no compensatory actions are necessary.

If for up to 30 days, the primary and alternate means of HCVS operation are non-functional, no compensatory actions are necessary.

If the out of service times exceed 30 or 90 days as described above, the following actions

will be performed: o The condition will be entered into the corrective action system, o The HCVS functionality will be restored in a manner consistent with plant procedures, o A cause assessment will be performed to prevent future loss of function for similar causes, per procedure. o Initiate action to implement appropriate compensatory actions.

-31 -The MNGP OIP describes programmatic controls that appear to be consistent with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. The NRC staff determined that procedure development appears to be in accordance with existing industry protocols. The provisions for out-of-service requirements appear to reflect consideration of the probability of an ELAP requiring severe accident venting and the consequences of a failure to vent under such conditions. 3.4.2 Training Order EA-13-109, Section 3.2, states that: 3.2 The licensee shall train appropriate personnel in the use of the HCVS. The training curricula shall include system operations when normal and backup power is available, and during an extended loss of AC power. Page 31 of the OIP states the following: Personnel expected to perform direct execution of the HVCS will receive necessary training in the use of plant procedures for system operations when normal and backup power is available and during ELAP conditions. The training will be refreshed on a periodic basis and as any changes occur to the HCVS. Training content and frequency will be established using the Systematic Approach to Training (SAT) process. In addition, all personnel on-site will be available to supplement trained personnel (Reference 10 [of the OIP]). The MNPS OIP describes HCVS training requirements that appear to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. The systematic approach to training process has been accepted by the NRC staff as appropriate for developing training for nuclear plant personnel. 3.4.3 Drills Order EA-13-109, Section 3.1, states that: 3.1 The licensee shall develop, implement, and maintain procedures necessary for the safe operation of the HCVS. Procedures shall be established for system operations when normal and backup power is available, and during an extended loss of AC power. Page 31 of the OIP states the following: The site will utilize the guidance provided in NEI 13-06 (Reference 12) and NEI 14-01 (Reference 13 [of the 01 P]) for guidance related to drills, tabletops, or

-32 -exercises for HCVS operation. In addition, the site will integrate these requirements with compliance to any rulemaking resulting from the Near-Term Task Force (NTTF) Recommendations 8 and 9. The MNGP OIP describes an approach to drills that appears to be in accordance with NEI 13-06, "Enhancements to Emergency Response Capabilities for Beyond Design Basis Accidents and Events" and NEI 14-01, "Emergency Response Procedures and Guidelines for Extreme Events and Severe Accidents." This approach appears to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. 3.4.4 Maintenance Order EA-13-109, Section 1.2.13, states that: 1.2.13 The HCVS shall include features and provisions for the operation, testing, inspection and maintenance adequate to ensure that reliable function and capability are maintained. Page 32 of the OIP states the following: The site will utilize the standard EPRI [Electric Power Research Institute] industry PM process (similar to the Preventive Maintenance Basis Database) for establishing the maintenance calibration and testing actions for HCVS components. The control program will include maintenance guidance, testing procedures and frequencies established based on type of equipment and considerations made within the EPRI guidelines. NSPM will implement the following operation, testing and inspection requirements for the HCVS to ensure reliable operation of the system. T bl 4 1 T a e -est1nQ an di nsoect1on R eauirements Description Freauencv Cycle the HCVS valves and the Once per operating cycle interfacing system valves not used to maintain containment integrity durinQ operations. Perform Visual inspections and a Once per operating cycle walk down of HCVS components. Test and calibrate the HCVS Once per operating cycle radiation monitors. Leak test the HCVS. (1) Prior to first declaring the system functional; (2) Once every three operating cycles thereafter; and (3) After restoration of any breach of system boundarv within the buildinas

-33 -Validate the HCVS operating Once per every other operating cycle procedures by conducting an open/close test of the HCVS control logic from its control panel and ensuring that all interfacing system valves move to their proper (intended) positions. The MNGP OIP describes an approach to maintenance that appears to be in accordance with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. Summary, Section 3.4: The licensee's approach to Programmatic Controls Training, Drills and Maintenance, if implemented as described in Section 3.4, and assuming acceptable resolution of any open items identified here or as a result of licensee alterations to their proposed plans, appears to be consistent with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing applicable requirements of Order EA-13-109. 4.0 OPEN ITEMS This section contains a summary of the open items identified to date as part of the technical evaluation. Open items, whether NRG-or licensee-identified, are topics for which there is insufficient information to fully resolve the issue, for which the NRG staff requires clarification to ensure the issue is on a path to resolution, or for which the actions to resolve the issue are not yet complete. The intent behind designating an issue as an open item is to highlight items that the staff intends to review further. The NRG staff has reviewed the licensee OIP for consistency with NRG policy and technical accuracy. The NRG-and licensee-identified open items have been identified in Section 3.0 and are listed in the table below. L' t f 0 't IS 0 ipen 1 ems Open Item Action Comment 1. Make available for NRG staff audit the final sizing evaluation for Section 3.2.1 HCVS batteries/battery charger including incorporation into Section 3.2.2.4 FLEX DG loading calculation. Section 3.2.3.1 Section 3.2.3.2 Section 3.2.4.1 Section 3.2.4.2 Section 3.2.5.1 Section 3.2.5.2 Section 3.2.6

-34 -2. Make available for NRC staff audit documentation of the HCVS Section 3.2.1 nitrogen pneumatic system design including sizing and location. Section 3.2.2.4 Section 3.2.3.1 Section 3.2.3.2 Section 3.2.4.1 Section 3.2.4.2 Section 3.2.5.1 Section 3.2.5.2 Section 3.2.6 3. Make available for NRC staff audit an evaluation of temperature Section 3.2.1 and radiological conditions to ensure that operating personnel Section 3.2.2.3 can safely access and operate controls and support equipment. Section 3.2.2.4 Section 3.2.2.5 Section 3.2.2.10 Section 3.2.4.1 Section 3.2.4.2 Section 3.2.5.2 Section 3.2.6 4. Make available for NRC staff audit analyses demonstrating that Section 3.2.2.1 HCVS has the capacity to vent the steam/energy equivalent of Section 3.2.2.2 one percent of licensed/rated thermal power (unless a lower value is justified), and that the suppression pool and the HCVS together are able to absorb and reject decay heat, such that following a reactor shutdown from full power containment pressure is restored and then maintained below the primary containment design pressure and the primary containment pressure limit. 5. Make available for NRC staff audit the seismic and tornado Section 3.2.2.3 missile final design criteria for the HCVS stack. 6. Make available for NRC staff audit the descriptions of local Section 3.2.2.5 conditions (temperature, radiation and humidity) anticipated Section 3.2.2.9 during ELAP and severe accident for the components (valves, Section 3.2.2.10 instrumentation, sensors, transmitters, indicators, electronics, control devices, etc.) required for HCVS venting including confirmation that the components are capable of performing their functions during ELAP and severe accident conditions. 7. Make available for NRC staff audit documentation that Section 3.2.2.5 demonstrates adequate communication between the remote HCVS operation locations and HCVS decision makers during ELAP and severe accident conditions. 8. Provide a description of the final design of the HCVS to address Section 3.2.2.6 hydrogen detonation and deflaqration. 9. Provide a description of the strategies for hydrogen control that Section 3.2.2.6 minimizes the potential for hydrogen gas migration and ingress into the reactor building or other buildinqs.

-35 -10. Make available for NRC staff audit descriptions of all Section 3.2.2.9 instrumentation and controls (existing and planned) necessary to implement this order includinQ qualification methods. 11. Make available for NRC staff audit documentation of an Section 3.2.2.9 evaluation verifying the existing containment isolation valves, relied upon for the HCVS, will open under the maximum expected differential pressure during BDBEE and severe accident wetwell venting. 5.0 SUMMARY As required by Order EA-13-109, the licensee has provided an OIP for designing and installing Phase 1 of a severe accident capable HCVS that provides venting capability from the wetwell during severe accident conditions, 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 OIP describes a HCVS wetwell vent 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 ELAP. The NRC staff finds that the licensee's OIP for Phase 1 of Order EA-13-109 describes: plan elements and assumptions; boundary conditions; provisions for programmatic controls, training, drills and maintenance; and an implementation schedule that appear consistent with the guidance found in NEI 13-02, endorsed, in part, by JLD-ISG-2013-02 as an acceptable means for implementing Phase 1 requirements of Order EA-13-109, subject to acceptable closure of the above open items.

-36 -6.0 REFERENCES 1. Order EA-13-109, "Issuance of Order to Modify Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions," June 6, 2013 (ADAMS Accession No. ML 13143A321 ). 2. Letter from Northern States Power Company to NRC, "MNGP's Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-1 3-109), dated June 30, 2014 (ADAMS Accession No. ML14183A412). 3. SECY-11-0093, "Recommendations For Enhancing Reactor Safety in The 2151 The Near-Term Task Force Review of Insights From The Fukushima Dai-lchi Accident," July 12, 2011 (ADAMS Accession No. ML 111861807). 4. SRM-SECY-11-0124, "Staff Requirements -SECY-11-0124 -Recommended Actions to be Taken Without Delay From The Near-Term Task Force Report, September 9, 2011 (ADAMS Accession No. ML 112911571). 5. SRM-SECY-11-0137, "Staff Requirements -SECY-11-0137 -Prioritization of Recommended Actions to be Taken in Response to Fukushima Lessons Learned," October 3, 2011 (ADAMS Accession No. ML 113490055). 6. SRM-SECY-11-0093, "Staff Requirements -SECY-11-0093 -Near-Term Report and Recommendations for Agency Actions following the Events in Japan, August 19, 2011 (ADAMS Accession No. ML 112310021 ). 7. SECY-12-0025, "Proposed Orders and Requests for Information in Response to Lessons Learned from Japan's March 11, 2011, Great Tohoku Earthquake and Tsunami, February 17, 2012 (ADAMS Accession No. ML 12039A 103). 8. SRM-SECY-12-0025, "Staff Requirements -SECY-12-0025 -Proposed Orders and Requests for Information in Response to Lessons Learned from Japan's March 11, 2011, Great Tohoku Earthquake and Tsunami, March 9, 2012 (ADAMS Accession No. ML 120690347). 9. Order EA-12-050, "Issuance of Order Modifying Licenses with Regard to Reliable Hardened Containment Vents, March 9, 2012 (ADAMS Accession No. ML 12054A694). 10. SECY-12-0157, "Consideration of Additional Requirements for Containment Venting Systems for Boiling Water Reactors with Mark I and Mark II Containments," November 26, 2012 (ADAMS Accession No. ML 12325A704). 11. SRM-SECY-12-0157, "Staff Requirements-SECY-12-0157, Consideration Of Additional Requirements For Containment Venting Systems For Boiling Water Reactors With Mark I And Mark II Containments, March 19, 2013 (ADAMS Accession No. ML13078A017).

-37 -12. NEI 13-02, "Industry Guidance for Compliance with Order EA-13-109," Revision 0, November 12, 2013 (ADAMS Accession No. ML 13316A853). 13. Interim Staff Guidance JLD-ISG-2013-02, "Compliance with Order EA-13-109, Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions," November 14, 2013 (ADAMS Accession No. ML 13304B836). 14. NRC Letter dated May 27, 2014, "Nuclear Regulatory Commission Audits Of Licensee Responses To Phase 1 of Order EA-13-109 to Modify Licenses With Regard To Reliable Hardened Containment Vents Capable Of Operation Under Severe Accident Conditions" (ADAMS Accession No. ML 14126A545). 15. Order EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," March 12, 2012 (ADAMS Accession No. ML 12054A735). 16. NRC Letter dated November 25, 2013, "Monticello Nuclear Generating Plant-Interim Staff Evaluation Relating to Overall Integrated Plan in Response to Order EA-12-049 (Mitigation Strategies) (TAC No. MF0923)" (ADAMS Accession No. ML 13220A139). 17. Letter from Northern States Power Company -Minnesota to NRC, "Monticello Nuclear Generating Plant's Overall Integrated Plan in Response to March 12, 2012 Commission Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events (Order Number EA-12-049)," dated February 28, 2013 (ADAMS Accession No. ML 13066A066). 18. NUREG-1935, "State-of-the-Art Reactor Consequence Analyses (SOARCA) Final Report" (ADAMS Accession No. ML 12332A058). Principal Contributors: Date: April 2, 2015 Bruce Heida Brian Lee Brett Titus Jerome Bettle Nageswara Karipineni Khoi Nguyen Steve Wyman Charles Norton P. Gardner If you have any questions, please contact Charles H. Norton, Project Manager, at 301-415-7818 or via e-mail at Charles.Norton@nrc.gov. Docket No. 50-263

Enclosure:

Interim Staff Evaluation cc w/encl: Distribution via Listserv DISTRIBUTION PUBLIC JOMB R/F RidsNrrDorllpl3-1 Resource RidsNrrPMMonticelloResource RidsNrrLASLentResource RidsAcrsAcnw_MailCTR Resource ADAMS Accession No.: ML15082A167 OFFICE NRR/JLD/JOMB/PM NRR/JLD/LA NAME CNorton Slent DATE 03/24/15 03/25/15 OFFICE NRR/JLD/JCBB/BC NRR/JLD/JOMB/BC (A) NAME SBailey MHalter IDATE 03/26/15 04/02/15 Sincerely, IRA/ Mandy K. Halter, Acting Chief Orders Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation RidsOGCMailCenter RidsRgn3Mai1Center Resource PBamford, NRR CNorton, NRR WReckley, NRR/JLD *via email NRR/DORULPL3-1 /PM NRR/JLD/JOMB/PM TBeltz PBamford 04/02/15 04/01 /15 OFFICIAL RECORD COPY

v t e Letter Sequence Other
TAC:MF4376, (Open)
Initiation Acceptance... Administration Questions Answers Results Approval... Other: L-MT-14-052, Mngp'S Phase 1 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order Number EA-13-109), L-MT-14-092, First Six-Month Status Report in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions, L-MT-15-031, Second Six-Month Status Report in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order EA-13-109), Phase 1, L-MT-15-090, Phase 2 Overall Integrated Plan in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order EA-13-109) Including Phase 1., L-MT-16-034, Fourth Six-Month Status Report in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions ..., L-MT-16-072, Fifth Six-Month Status Report in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions (Order EA-13-109), L-MT-17-042, Sixth Six-Month Status Report in Response to June 6, 2013 Commission Order Modifying Licenses with Regard to Reliable Hardened Containment Vents Capable of Operation Under Severe Accident Conditions, ML15082A167, ML16244A120
MONTHYEAR2015-06-22 [Table View]

ML15082A167

Text

SUBJECT:

Dear Mr. Gardner:

Enclosure:

1.0 INTRODUCTION

2.0 REGULATORY EVALUATION

3.0 TECHNICAL EVALUATION

Enclosure:

Navigation menu

Search