ML17270A179
| ML17270A179 | |
| Person / Time | |
|---|---|
| Site: | NuScale |
| Issue date: | 09/26/2017 |
| From: | Rad Z NuScale |
| To: | Document Control Desk, Office of New Reactors |
| References | |
| RAIO-0917-56087 | |
| Download: ML17270A179 (15) | |
Text
RAIO-0917-56087 September 26, 2017 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738
SUBJECT:
NuScale Power, LLC Response to NRC Request for Additional Information No.
163 (eRAI No. 8907) on the NuScale Design Certification Application
REFERENCE:
U.S. Nuclear Regulatory Commission, "Request for Additional Information No.
163 (eRAI No. 8907)," dated August 11, 2017 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) response to the referenced NRC Request for Additional Information (RAI).
The Enclosure to this letter contains NuScale's response to the following RAI Questions from NRC eRAI No. 8907:
09.03.03-1 09.03.03-2 09.03.03-3 09.03.03-4 This letter and the enclosed response make no new regulatory commitments and no revisions to any existing regulatory commitments.
If you have any questions on this response, please contact Carrie Fosaaen at 541-452-7126 or at cfosaaen@nuscalepower.com.
Sincerely, y,
Zackary W. Rad
- Director, Di t Regulatory R l t Affairs Aff i NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A Anthony Markley, NRC, OWFN-8G9A (QFORVXUH 1X6FDOH5HVSRQVHWR15&5HTXHVWIRU$GGLWLRQDO,QIRUPDWLRQH5$,1R
NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
NuScale Response to NRC Request for Additional Information eRAI No. 8907 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
Response to Request for Additional Information Docket No.52-048 eRAI No.: 8907 Date of RAI Issue: 08/11/2017 NRC Question No.: 09.03.03-1 GDC 60 requires, in part, a power unit design to include means to control suitably the release of radioactive materials in liquid effluents produced during normal reactor operation, including anticipated operating occurrences. 10 CFR 52.6 requires, in part, that information provided to the Commission under Part 52 shall be complete and accurate in all material respects.
FSAR Tier 2, Section 9.3.3.2.1, indicates that the radioactive waste drainage system (RWDS) and balance-of-plant drainage system (BPDS) are designed to include surge capacity to support other routine activities such as runoff from firefighting activities. The FSAR shows and describes that firewater removal pumps are provided in certain sumps, but not all, to aid in removal of liquids in those sumps and prevent overflow of the sumps. FSAR Tier 2, Figure 9.3.3-2, Balance-of-plant Drain System Diagram, shows some sumps having a firewater removal pump while FSAR Tier 2, Figure 9.3.3.-1, "Radioactive Waste Drain System Diagram," shows none. It is not clear to the staff why some sumps, such as the Chemical Waste Collection Sump which receives drainage from floor drains, do not have this extra pump.
The applicant is requested to provide clarification on why firewater removal pumps are not required for some sumps. The FSAR is to be modified accordingly. In addition, describe the expected surge volumes, the capacity of the drain systems components designed to accommodate these surge volumes, and provide the basis for ensuring the sumps are sized appropriately or provide a COL information item to capture this design information.
NuScale Response:
FSAR Section 9.3.3.2.2, under the Pumps heading, states that the basis for the RWDS drain pump capacity is to accommodate the maximum anticipated flow into the sump, and that each such pump has a backup.
FSAR Section 9.3.3.2.2, under the Sumps and Tanks heading, states that the basis for the capacity of the firewater removal pumps is to accommodate the design basis fire suppression system flows. A sentence was added explaining that chemical waste collection sumps are not equipped with firewater removal pumps because they do not receive floor runoff. Under the NuScale Nonproprietary
same heading, there is an explanation that the flooding analysis for the Reactor Building concluded that pooling from fire suppression equipment does not impact safety-related or risk-significant equipment.
Statements have been added to FSAR Section 9.3.3 to more fully describe the design basis of the RWDS in the Control Building, and to clarify the basis for the reactor component cooling water drain tank capacity.
Impact on DCA:
FSAR Section 9.3.3 has been revised as described in the response above and as shown in the markup provided in this response.
NuScale Nonproprietary
NuScale Final Safety Analysis Report Process Auxiliaries provisions for preventing the backflow of combustible liquids into safety-related areas through the interconnected drain systems.
The BPDS uses double-walled lines with built-in leak detection capability in the piping between the TGB sumps to the LRWS, to contain radioactive material and prevent contamination spread from buried pipe. The connections and fittings for potentially contaminated BPDS tanks are welded in order to prevent leakage.
9.3.3.2.2 Major Component Description Sumps and Tanks The RWDS is designed to collect, accumulate, and transfer the expected amounts of radioactive liquid wastes to the LRWS, including chemical and detergent bearing wastes. The RWDS has excess capacity which supports periodic maintenance or other volume increases greater than routine operating capacities. Redundant pumps provide backup.
RAI 09.03.03-1 The RXB internal flooding analysis for the RXB determined that pooling from fire suppression equipment does not impact safety-related or risk-significant equipment functions with no credit taken for the floor drain system, as described in Section 3.4. There are no safety-related or risk significant SSCs on the lowest level of the CRB. In the event of fire suppression system activation, the excess water is allowed to pool on the impacted floor until it can drain into the floor drain sump tank. Floor drains from upper elevations are collected and routed through individual downcomers to the nearest floor drain sump, located in the lowest elevation. This feature prevents water collected on one floor from backing up to other floors. The RWDS sumps in the RXB, though not credited to prevent flooding in the respective buildings, will attenuate to some extent the flood levels from design basis fire suppression system flows. The BPDS sump in the CRB contains a fire water removal pump rated at the maximum single zone fire suppression system flow rate.
The RWDS sumps are provided with stainless steel liners to collect any leakage from the primary tank. The liners also contain leak detection which alarms in the Waste Management Control Room (WMCR). The sumps are covered to keep out debris, with an access port to facilitate inspection and cleanout operations. The RWDS tanks are vented to the RXB or RWB ventilation system which helps prevent gaseous and airborne radioactive contaminants from leaving the sump tanks by a path other than the vent piping.
RAI 09.03.03-1 The BPDS is designed to accommodate normal drainage into each of the five sumps. Sufficient storage volume and pump-out capacity is provided in the BPDS collection tanks to process normal and infrequent operational occurrences. The two TGB waste water sumps and the CRB sump are also equipped with firewater removal pumps sized to accommodate the design basis fire suppression system flows in the respective buildings without flooding. The chemical waste collection Tier 2 9.3-47 Draft Revision 1
NuScale Final Safety Analysis Report Process Auxiliaries sumps are not equipped with firewater removal pumps because these sumps do not receive runoff from floors.
The BPDS sumps are closed tanks. The BPDS design provides positive leakage containment that excludes precipitation, groundwater, and runoff. The waste water sumps associated with the BPDS are equipped with coalescing media. Oily waste collected in the BPDS waste water sumps is processed by a BPDS oil separator to permit oily waste collection and transport offsite.
Underground tanks in the BPDS, regardless of material, are located in concrete enclosures with leak detection for secondary containment and covers to exclude precipitation. Each sump includes two pumps. The first pump turns on at high level.
The second pump turns on at high-high level. All pumps turn off at low level. For the three tanks with firewater removal pumps, that pump turns on at high-high-high level.
RAI 09.03.03-1 The RCCW drain tank is sized to accept the RCCW water contained in the single largest piece of equipment in the RCCW circuit. The chemical drain tank is sized to accept waste from the process sampling system and the 12 containment evacuation systems.
Pumps Cleanable screens are installed on pump suction lines to minimize the potential for pump damage or plugging of system piping. The RWDS chemical drain tanks are provided with air diaphragm transfer pumps. The RCA drainage, with the exception of detergent waste, is collected by various RWDS drain tanks, each having two redundant pumps. Each pump is sized to accommodate the maximum anticipated flow into the sump. Thus, each sump has one pump ready for operation and one pump on standby. The pumps automatically start and stop based on level indication. The first pump is activated upon the tank reaching high level and the second pump is activated upon reaching high-high level. This provides automatic backup if one pump fails or if the inflow exceeds the capacity of one pump.
9.3.3.2.3 System Operation The RWDS and BPDS operate during normal operation, maintenance, plant shutdowns, refueling, plant startup operations, and during anticipated operational occurrences.
For RWDS normal operation, liquid wastes drain by gravity to collection tanks or sumps. Sump pumps discharge the collected radiologically contaminated liquid wastes to the LRWS for further processing.
The RCCW drain and chemical drain subsystems receive waste, but transfer to the LRWS is manually initiated after sampling, analysis, and adjustment if necessary.
The liquids contained in the RCCW drain tank are normally not radiologically contaminated but contain various treatment chemicals, including corrosion Tier 2 9.3-48 Draft Revision 1
NuScale Final Safety Analysis Report Process Auxiliaries sump tanks were to fail as the result of an earthquake, the sumps (secondary containments) would still be intact and capable of containing the liquid waste, with no adverse interaction with safety-related or risk significant equipment.
The RWDS and BPDS do not require protection against external flooding as the plant site selection criteria places the maximum external flood level at one foot below grade.
General Design Criterion 4 was considered in the design of the RWDS and BPDS.
Consistent with GDC 4, the design of the RWDS and BPDS provides protection of safety-related and risk-significant SSC from the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents. The design of the RWDS and BPDS ensures that safety-related equipment functions are not impacted by undue water accumulations within the plant. The internal flood analysis provided in Section 3.4.1 evaluates the potential flooding impact on SSC due to pipe breaks, equipment failures, and fire suppression water. The RWDS and BPDS are not safety-related, single-failure proof, or seismically designed. The flood analysis takes no credit for water removal by the RWDS or BPDS. In some areas of the RXB and CRB, the flood analysis identifies the need for implementing elevated equipment mounting details, waterproof design features, or watertight doors to minimize impact from water accumulation as described in Section 3.4. Implementation of the measures identified by the internal flood analysis ensures that safety-related equipment functions are not impacted by water accumulations within the plant.
RAI 09.03.03-1 The BPDS waste water drain tanks that serve the TGBs and the CRB sump contain fire water removal pumps rated for the design basis fire suppression system flow in the respective buildings. The subsystems operate automatically without the need for operator intervention. The design of the RWDS can help mitigate the consequences of flooding from internal sources, such as pipe breaks, tank leaks, discharge from fire suppression systems, and other potential flooding sources, by providing waste collection and transfer capability. The chemical waste collection sumps do not require firewater removal pumps, as these sumps do not receive runoff from floors.
General Design Criterion 5 was considered in the design of the RWDS and BPDS.
Consistent with GDC 5, although the RWDS and BPDS are shared by up to 12 NPMs, in the event of an accident in one NPM, the failure of these systems to perform their nonsafety-related functions does not prevent an orderly shutdown and cooldown of the remaining NPMs.
General Design Criterion 60 was considered in the design of the RWDS and BPDS.
Consistent with GDC 60, the RWDS and BPDS designs control the release of radioactive materials in gaseous and liquid effluents during normal operations including anticipated operational occurrences. RWDS and BPDS process radiation monitoring and automated functions described in Section 9.3.3.5 limit the release of radioactive materials, conforming to GDC 60.
The design of the RWDS and BPDS considers as low as reasonably achievable and minimization of contamination guidelines. Consistent with 10 CFR 20.1101(b), the design of the RWDS and BPDS supports keeping radiation exposures ALARA. To Tier 2 9.3-51 Draft Revision 1
Response to Request for Additional Information Docket No.52-048 eRAI No.: 8907 Date of RAI Issue: 08/11/2017 NRC Question No.: 09.03.03-2 GDC 60 requires, in part, a power unit design to include means to control suitably the release of radioactive materials in liquid effluents produced during normal reactor operation, including anticipated operating occurrences. 10 CFR 52.6 requires, in part, that information provided to the Commission under Part 52 shall be complete and accurate in all material respects.
Regarding FSAR Tier 2, Figure 9.3.3-2, Balance-of-plant Drain System Diagram, the staff found a clarification needed in order to make a reasonable determination that the equipment and floor drainage system meets the above requirements. FSAR Tier 2, Section 10.4.2.3 states, in part, that [contaminated] liquid detected in the condenser air removal system (CARS) relies on the balance-of-plant drain system to route it to the radioactive waste drain system for appropriate processing. However, the CARS system is not reflected in Figure 9.3.3-2.
The applicant is requested to provide additional information in the FSAR, including within Figure 9.3.3-2, to accurately depict the inputs and outputs of the drainage sumps and the means by which to isolate each flowpath.
NuScale Response:
FSAR Section 10.4.2.3 has been revised to indicate that the CARS normally drains to the condenser, but has the capability to drain to the BPDS. FSAR Figure 9.3.3-2 has been revised to show that flow from the sumps of several buildings to the BPDS waste water sumps can be manually isolated. Water is pumped from the sumps of these buildings to the waste water sumps. Flow from the TGB floor drains to the waste water sumps is by gravity, and no isolation is provided or required.
Flow from CARS to BPDS is not shown on the figure because normal flow is to the condenser.
Text was added to FSAR Section 9.3.3 to provide a better description of the design for flow of water to the waste water sump tanks.
NuScale Nonproprietary
Impact on DCA:
FSAR Sections 9.3.3 and 10.4.2.3 and FSAR Figure 9.3.3-2 have been revised as described in the response above and as shown in the markup provided in this response.
NuScale Nonproprietary
NuScale Final Safety Analysis Report Process Auxiliaries
The majority of the BPDS is constructed of carbon steel. The BPDS chemical waste subsystem and the RWDS are constructed of austenitic stainless steel. This material handles corrosive materials and facilitates decontamination from radioactive material.
The RWDS and BPDS are composed of pumps, sumps, tanks, instrumentation, controls, and piping.
RAI 09.03.03-2 The simplified system layout of the RWDS is shown in Figure 9.3.3-1. Figure 9.3.3-2 shows the simplified layout of the BPDS. Water is pumped from the sumps of several buildings to the waste water sump tanks. At the point at which each of these lines enters the waste water sump tanks, there is an air separation between the pipe and the water level in the tank, preventing reverse flow. In addition, each of these lines includes a manual isolation valve. For the TGBs, however, flow to the waste water sump tanks is by gravity and no isolation valve is provided.
Table 9.3.3-1 lists the collection areas for the RWDS and BPDS.
The design of the RWDS and BPDS directs waste liquids, valve and pump leakoffs, and component drains and vents to the proper area for processing or disposal. The RWDS and BPDS are designed to include surge capacity to support periodic maintenance activities as well as other volume increases due to other than routine operations (e.g., forced outages, runoff from firefighting activities, and decontamination activities).
Influent source streams into the BPDS that have the potential to contain radioactive material are provided with radiation monitors that support automated system functions to terminate related sump tank discharge flow and allow for manual diversion of the effluent stream to the LRWS upon detection of radioactivity that is greater than predetermined thresholds. The BPDS radiation monitors and automated functions are discussed in Section 9.3.3.5.
The RWDS and BPDS provide the capability to manually sample collected waste.
The RWDS collects, accumulates, and allows sampling of both radiologically contaminated and non-contaminated liquid wastes in the RCA then transfers the waste to the LRWS for processing. The BPDS collects, accumulates, and samples liquid wastes that are normally not radiologically contaminated from buildings outside of the RCA (Table 9.3.3-1).
Capped hose connections piped to equipment drain sumps are available near large equipment in the RCA. Equipment drains use permanent connections or temporary hose connections to RWDS drain tanks to prevent the spread of airborne contamination. Cold demineralized water is available to dilute hot waste streams entering an RWDS sump to maintain the required net positive suction head on the sump pumps.
Tier 2 9.3-45 Draft Revision 1
Tier 2 NuScale Final Safety Analysis Report RAI 09.03.03-2 Figure 9.3.3-2: Balance-of-Plant Drain System Diagram TGB Floor Drains Oily Waste Diesel Generator Floor Drains OILY Aux Boiler RC WASTE TO OFFSIDE DISPOSAL Floor Drains TANK Waste Water Comb. Turbine Sumps (2)
Floor Drains CUB Floor Drains Oily Waste Firewater Pump BPDS Collection House Floor Drains 9.3-61 Tanks (2)
TO OFFSITE DISPOSAL Aux Boiler Blowdown Control Bldg Sump (1)
CRB Floor Drains Condensate Polisher Regenerant Chem. Treatment Bldgs Floor Drains Chemical Waste Liquid Radwaste DWS Reverse Osmosis Collection Sumps (2) System Rejects RC Draft Revision 1 Process Auxiliaries
NuScale Final Safety Analysis Report The CARS design satisfies the requirements of 10 CFR 20.1406 as it relates to minimization of contamination of the facility. The CARS monitors the removed gases for radioactivity and transfers detected radioactive materials to the radwaste processing systems. Further discussion of the facility design features to protect against contamination is provided in Section 12.3.
09.03.03-2 Detected radioactive material at or above the limits established in 10 CFR 50, Appendix I is isolated in the CARS. The CARS usesnormally drains to the condenser, but includes manually operated valves that allow contaminated fluids to be routed to the balance-of-plant drain system, to route liquidwhich can then be routed to the liquid radioactive waste drain system for appropriate processing during or after a contamination event.
The CARS has redundant components to ensure that a single component failure does not lead to a loss of condenser vacuum and a subsequent turbine trip. A failure of the CARS does not impact the safe operation of the NPM nor affect safety-related equipment. The CARS has no direct impact on the primary system or the secondary systems. A failure of the CARS results in a slow increase in MC pressure. The loss of MC vacuum trip setpoint is designed so that a turbine trip is initiated before a reactor trip.
The loss of MC vacuum condition is described in Section 15.2.3.
10.4.2.4 Inspection and Testing The CARS and its components are inspected and tested as part of the initial testing and startup program as described in Section 14.2. Plant startup testing and inspection is performed prior to plant operation. The CARS design provides for on-line testing to determine the amount of exhaust flow and monitor MC performance and leakage rates. Flow measuring instrumentation is provided to determine the exhaust flow from the NPM.
The ITAAC are addressed in Section 14.3.
10.4.2.5 Instrumentation The following instrumentation and controls are provided to monitor and control the system and components of the CARS. Details are shown in Table 10.4-4.
- Temperature monitors are provided for the seal water loop at the inlet side of the LRVP to maintain the temperature below the MC temperature.
- Pressure monitors are provided at the suction of the LRVP with differential pressure provided at the flow control valve.
- The seal water separator tank is provided with level monitoring and level control for tank makeup and letdown. This controls the water for the seal in the LRVP as well.
- A flow gauge is attached to the separator tank for manual measurement of the LRVP exhaust flow. It is used to quantify inleakage and gas, including non-condensable gas removed from the MC.
Tier 2 10.4-11 Draft Revision 1
Response to Request for Additional Information Docket No.52-048 eRAI No.: 8907 Date of RAI Issue: 08/11/2017 NRC Question No.: 09.03.03-3 10 CFR 52.6(a) states, in part, that the information provided by an applicant for a standard design certification shall be complete and accurate in all material respects. GDC 2 requires, in part, the capability of important to safety system portions of the equipment and floor drainage system (EFDS) to withstand the effects of natural phenomena (such as seismic event, floods, etc.) without loss of capability to perform safety functions.
As stipulated in Section III.2 of Standard Review Plan (SRP) Section 9.3.3, Equipment and Floor Drainage System, the drawings and descriptions are reviewed for whether safety-related EFDS portions are identified correctly and can be isolated from nonsafety-related portions.
Regulatory Guide 1.29, Revision 4, Regulatory Position C.2 states that those structures, systems, components (SSCs) of which continued function is not required but of which failure could reduce the functioning of any plant feature included in Regulatory Position C.1 to an unacceptable safety level should be designed and constructed so that the safe shutdown earthquake (SSE) would not cause such failure.
FSAR Tier 2 Table 3.2-1, Classification of Structures, Systems, and Components, under radwaste drainage system (RWDS) (FSAR page 3.2-11), lists the RWDS Seismic Classification as III. However, FSAR Tier 2, Section 9.3.3.1 states that portions of the [RWDS and balance-of-plant drainage system (BPDS)] system that are in proximity to Seismic Category I SSCs are designed to Seismic Category II standards. Without proper classification of a system's components, failures of those portions could damage important to safety equipment.
The applicant is requested to clarify the proper classification of the various portions of the EFDS. If there are portions that need to be Seismic Category II, the applicant is requested to identify those system portions in the FSAR.
In addition, FSAR Tier 2 Section 9.3.3.1 suggests there are sections within proximity of Seismic Category 1 SSCs. However, there was no definition/specification provided to quantify in proximity. The applicant is requested to provide clarification in the FSAR on what is defined as in proximity.
NuScale Nonproprietary
NuScale Response:
FSAR Table 3.2-1 indicates that all components in both the RWDS and the BPDS are designed to Seismic Category III standards. NuScale recognizes that the final layout of the plant may result in certain components in these systems located such that they will need to be designated Seismic Category II. In response to RAI 9.2.2-1, NuScale added the following footnote to FSAR Table 3.2-1:
Where SSC (or portions thereof) as determined in the as-built plant which are identified as Seismic Category III in this table could, as the result of a seismic event, adversely affect Seismic Category I SSC or result in incapacitating injury to occupants of the control room, they are categorized as Seismic Category II consistent with Section 3.2.1.2 and analyzed as described in Section 3.7.3.8.
FSAR Tier 1 includes the following ITAAC to verify the appropriate seismic classification of SSCs in the Reactor Building and the Control Building:
Reactor Building: Tier 1 Table 3.11-2, item 7 Control Building: Tier 1 Table 3.13-1, item 5 There are no Seismic Category I SSC in the Radioactive Waste Building and, therefore, no ITAAC is needed to verify seismic classification in the Radioactive Waste Building.
Impact on DCA:
There are no impacts to the DCA as a result of this response.
NuScale Nonproprietary
Response to Request for Additional Information Docket No.52-048 eRAI No.: 8907 Date of RAI Issue: 08/11/2017 NRC Question No.: 09.03.03-4 GDC 60 requires, in part, a power unit design to include means to control suitably the release of radioactive materials in liquid effluents produced during normal reactor operation, including anticipated operating occurrences. 10 CFR 52.6 requires, in part, that information provided to the Commission under Part 52 shall be complete and accurate in all material respects.
FSAR Tier 2, Sections 9.3.3 and 14.2 provide high-level descriptions about the testing, inspection, and maintenance of the equipment and floor drainage system. However, it is unclear to the staff which components will be inspected, tested, and maintained throughout the life of the plant. Inspection, testing, and maintenance is important to prevent radioactive liquid effluents from leaking and contaminating areas of the plant.
The applicant is requested to provide further information regarding the periodic inspection, testing, and maintenance of the equipment and floor drainage system (include both radioactive waste drainage system (RWDS) and balance-of-plant drainage system (BPDS)).
NuScale Response:
COL Item 12.3-7 requires the COL applicant to develop processes and programs to demonstrate compliance with 10 CFR 20.1406 and, therefore, GDC 60. These processes and programs will determine the SSC to be included in the testing and inspection program in accordance with regulatory position C.2.3 of Regulatory Guide 4.21.
Impact on DCA:
There are no impacts to the DCA as a result of this response.
NuScale Nonproprietary