ML18264A312

LLC Submittal of Resolution Plans and Classification for ECCS Valve FMEA Audit Follow-Up Items

ML18264A312
Person / Time
Site:	NuScale
Issue date:	09/21/2018
From:	Rad Z NuScale
To:	Document Control Desk, Office of New Reactors
References
LO-0918-61910
Download: ML18264A312 (13)

Text

LO-0918-61910 September 21 , 2018 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 Submittal of Resolution Plans and Classification for ECCS Valve FMEA Audit Follow-Up Items

REFERENCES:

1. Letter from NuScale Power, LLC to Nuclear Regulatory Commission , "NuScale Power, LLC Submittal of the NuScale Standard Plant Design Certification Application , Revision 1," dated March 15, 2018 (ML18086A090)

2. "U.S. Nuclear Regulatory Commission Staff Report of Regulatory Audit of Failure Modes and Effects Analysis and other Supporting Documents for Emergency Core Cooling System Valves in the NuScale Power LLC , Design Certification Application",

dated August 14, 2018 , (ML18219B634)

During an August 15, 2018 public teleconference with Ms. Marieliz Vera , Mr. Tim Lupold , and Mr. Tom Scarborough of the NRC staff, NuScale Power, LLC (NuScale) discussed a proposed path forward for resolution of certain follow-up items from the Reference 2 audit report. As a result of this discussion ,

NuScale submits the proposed closure plan for these follow-up items (see Attachment 1). In addition ,

NuScale classified each of the Reference 2 audit report follow-up items to reflect its resolution status and resolution plan. During a subsequent September 4, 2018 , public teleconference with Ms. Marieliz Vera , Mr. Tim Lupold and Mr. Tom Scarborough , NuScale agreed to transmit this follow-up item classification and it is included as Attachment 2 to this letter.

This letter makes no regulatory commitments or revisions to any existing regulatory commitments.

If you have any questions , please feel free to contact Mr. Marty Bryan at 541-452-7172 or at MBryan@nuscalepower.com Sincerely, Zackary W. Rad Director, Regulatory Affairs NuScale Power, LLC Distribution: Samuel Lee, NRC , OWFN-8G9A Gregory Cranston , NRC , OWFN-8G9A Timothy Lupold , NRC, OWFN-8G9A Marieliz Vera , NRC, OWFN-8G9A Thomas Scarborough , NRC , OWFN-8G9A : "NuScale Power's Resolution Plan for ECCS Valve FMEA Audit Follow-Up Items" : "NuScale ECCS Valve FMEA Audit Follow-Up Item Classification Report" NuScale Power, LLC 1100 NE Circle Blvd , Suite 200 Corvallis, Oregon 97330 Office 541.360-0500 Fax 541.207.3928 www.nuscalepower.com

NuScale Powers Resolution Plan for ECCS Valve LO-0918-61910 FMEA Audit Follow-Up Items Attachment 1 Page 1 of 2

1. Partial Open ECCS Valve Failure Mode Resolution Plan In the Reference 2 audit report, the staff identified technical aspects requiring resolution regarding a partial open failure mode for the ECCS valves. In response, NuScale proposes to finalize preliminary vendor calculations reviewed by the Staff during the ECCS Valve FMEA audit at the vendors facility in Farmingdale New York. The finalized calculations will be issued as quality assurance products meeting applicable portions of the vendors NQA-1 program. The calculations are expected to demonstrate it is not credible that 1) tilting during actuation could cause binding in a partial open state; and, that 2) the force balance across the main valve disc is such that the valve disc cannot remain in a partial open state for an extended period of time (i.e., will move to a fully open or closed position).

2. ECCS Valve Performance Demonstration Plan In the Reference 2 audit report, the staff identified items requiring resolution to support application of the 2015 POC test results for demonstrating performance of the final design ECCS valve system.

Additionally, the staff considers that the 2015 POC test does not address valve performance for all fluid conditions under which the ECCS valves are required to operate. In response, NuScale proposes to perform additional functional testing similar in scope as the 2015 POC test, but with a range of fluid conditions representative of the NuScale Power Module (NPM) reactor operating conditions. This DCA Demonstration test will entirely supersede any and all testing performed as part of the 2015 POC testing with respect to supporting the ECCS valve design in the DCA review phase. Tests will be performed with fluid conditions that are representative of reactor rector vent valve (RVV) conditions, and reactor recirculation valve (RRV) conditions. A range of test fluid conditions will be used to represent LTOP (lower temperature) conditions and reactor operating conditions.

The proposed DCA Demonstration test will be performed with the same main valve mockup (2 inch) utilized in the 2015 testing, which is functionally and geometrically similar to the RRV main valve. A representative inadvertent action block (IAB) and trip valve will be used in combination with the main valve to form the complete ECCS valve system. The DCA Demonstration test valve configuration will include hydraulic tubing that bounds the limiting configuration of tubing in the ECCS DCA design (tubing volume and elevation). NuScale proposes to provide an evaluation of the DCA Demonstration testing results to demonstrate that the results of the hot testing on the 2 inch valve (similar to an RRV) with representative RVV fluid conditions can be extrapolated to the 5 inch RVV.

Acceptance criteria for main valve actuation tests will be that the main valves open fully under the IAB release pressure. Acceptance criteria for the IAB functional tests will be that opening of the main valve, is prevented, for pressure above the threshold pressure (1200 psi maximum) and permitting main valve opening below the release pressure (1000 psi minimum).

The proposed functional demonstration testing of the ECCS valve system (main valve, IAB, tubing, and trip valve) will be performed with water only and not a boric acid solution. NuScale proposes to perform separate effects testing with the inadvertent actuation block (IAB) device, trip valve, and associated tubing, with a hot boric acid solution.

2.1 Boric Acid Effects Test:

The boric acid effects test will consist of a heated and pressurized reservoir to represent the ECCS main valve control chamber, an IAB of representative geometry to the DCA ECCS design, and a trip valve with tubing length and flow path areas which are representative of the DCA ECCS design. The reservoir will be heated, such that flashing occurs during the blowdown through the trip line. A separate pressure source may be used to represent the RCS reference pressure to the IAB.

NuScale Nonproprietary

NuScale Powers Resolution Plan for ECCS Valve LO-0918-61910 FMEA Audit Follow-Up Items Attachment 1 Page 2 of 2 The test will be performed by pressurizing both the RCS reference pressure source and the heated reservoir. The initial RCS reference pressure will be above the IAB threshold pressure (maximum threshold pressure is 1200 psi). The trip valve will be opened to trigger IAB closure.

The RCS reference pressure source will be manually reduced until the IAB opens to permit depressurization of the system. This test will be performed (a) with water only, and (b) with boric acid solution representative of the maximum expected concentrations in the NuScale coolant.

Performing the same tests with and without boric acid in the test fluid will provide a means of evaluating its effects on the performance of the ECCS valve system.

Boric Acid Effects Test Evaluation and Acceptance Criteria:

The pressure plots for the test(s) with water only and the test(s) with boric acid solution in the simulated control chamber reservoir will be compared. Acceptance criteria will be insignificant differences in IAB performance and blowdown through the trip line (as observed from pressure plots) in the boric acid solution test(s) compared to the water only test(s).

The proposed tests will include appropriate quality controls to the dimensional checks, instrumentation, test performance, and test records. Safety-related material requirements are not applicable because these test components are not SSCs to be installed in an operating plant.

3. Attachment 2 Summary The audit items marked as simple fix in the category column of attachment 2 will have actions performed as indicated in the NRC Notes Column.

The audit items marked as no action (for the scope of this audit) or resolved do not require further action to support resolution of audit items.

The audit items marked TECH ISSUE - PARTIAL OPEN in attachment 2 to this letter will be addressed by completion of the calculation(s) described in the partial open resolution plan above.

These items correspond to index numbers 19, 10, 11, 12, 13, 35, 52, and 95 in attachment 2.

The audit items marked TECH ISSUE - POC TESTING and TECH ISSUE - VALVE SYSTEM OPERATION AT OPERATING CONDITIONS in attachment 2 to this letter will be addressed by the demonstration testing activities described in this letter. These items correspond to index numbers 1, 2, 3, 5, 6, 7, 8, 32, 33, 34, and 36 in attachment 2.

NuScale will provide written responses to address each of the remaining items as identified below:

TECH ISSUE - NON-VALVE FAILURE MODES EVAL (power/tubing) [Index # 28, 39, 64]

TECH ISSUE - DIFFUSER REVERSE FLOW [Index # 37]

TECH ISSUE - MAIN VALVE SPRING CREDIT FOR SAFETY [Index #43]

TECH ISSUE - ADDRESS DAVIS BESSE LESSONS LEARNED Index #46]

TECH ISSUE - VALVE INTERNAL FILTER PERFORMANCE [Index #47, 53, 57]

4. Conclusion The above described calculations, reports, revisions, and testing results will be made available for NRC audit by June 2019, contingent on schedule confirmation, and are intended to close audit follow-up items, as discussed above, in Reference 2.

NuScale Nonproprietary

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NuScale ECCS Valve FMEA Audit Folow-Up Item Attachment 2

Classification Report Page 1 of 10

1. sub Subject/Item Category Index NRC Notes

- - Proof of Concept (POC) Testing, 2015 - - -

The proof-of-concept (POC) test report identifies key aspects to be addressed during the detailed design and testing such as the following: (a) sizing of the trip valve is critical for the trip valve to adequately vent the trip line to allow operation of the main valve and to allow the inadvertent actuation block (IAB) valve to immediately seat to prevent premature opening of the main valve; (b) sizing of the trip line, fittings, and orifice is critical to adequately vent the trip line; (c) in that the proof-of-concept testing included only air and water tests, the effects of hot water, steam, and flashing will need to be assessed; and (d) the effect on valve performance from the differences between test facilities and the reactor pressure vessel (RPV) will need to be assessed. NuScale should address these key aspects identified in the 1 - POC test report to demonstrate the safety features of the ECCS valves and their valve subcomponents. tech issue 1 TECH ISSUE - POC TESTING 2 - NuScale should address the following items for application of the POC test results to the final design of the reactor vent valve (RVV) and reactor recirculation valve (RRV) for the ECCS valves: - - -

TECH ISSUE - VALVE SYSTEM

- a Applicability of the POC test fluid conditions to the reactor fluid conditions for temperature, pressure, and borated water. tech issue 2 OPERATION AT OPERATING CONDITIONS Applicability of the POC test valve size and tubing length, routing, and volume to the final ECCS valve system design to support the assumptions for IAB valve performance and validate IAB valve

- b calculations. tech issue 3 TECH ISSUE - POC TESTING

- c Adequacy of the POC test results to support the passive component assumption for the IAB valve in the safety analysis. tech issue 4 TECH ISSUE - IAB PASSIVE

- d Reliability of the POC test data for traceability and calibration of the pressure transducers and main disc position linear variable differential transformer (LVDT) used in the POC testing. tech issue 5 TECH ISSUE - POC TESTING Applicability of the internal dimensions of the valves used in POC testing to the final RRV design. For example, the following information for the POC test equipment should be compared to the final ECCS valve design: (1) main valve and IAB valve internal dimensions and clearances; (2) internal volumes (main valve control chamber, IAB valve above and below bellows, and tubing); (3) main valve and IAB valve spring sizes, constants, and preloads; (4) valve seat sizes (main valve, IAB valve, trip valve, and reset valve); (5) main valve orifice and filter; (6) main valve and trip valve elevation difference and

- e tubing routing; and (7) line flow restrictions (e.g., adapters, fittings, and line internal dimensions). tech issue 6 TECH ISSUE - POC TESTING Applicability of the POC testing of a 2-inch valve (similar to the RRV) to the performance of the 5-inch RVV for reactor fluid conditions and applicable accident scenarios, including low temperature

- f overpressure protection (LTOP). tech issue 7 TECH ISSUE - POC TESTING 3 - NuScale should describe its plans to resolve the safety questions regarding the design demonstration testing of the ECCS valves to support the DC application. tech issue 8 TECH ISSUE - POC TESTING

- - Partial Open ECCS Valve Failure Mode - - -

1 - NuScale should address the following technical aspects in resolving the safety questions regarding a partially open failure mode for an ECCS valve: - - -

- a The main valve needs to be demonstrated to not be subject to tilting that could cause binding during valve actuation by the opening flow for the RVV and RRV, including diffuser turbulent flow for the RVV. tech issue 9 TECH ISSUE - PARTIAL OPEN

- b The pressure drop in the main valve control chamber upon operation of the IAB valve needs to be evaluated to demonstrate that the main valve will not open prematurely. tech issue 10 TECH ISSUE - PARTIAL OPEN The preliminary calculations of the performance of the main valve upon partially opening need to be completed and verified with justification by analysis or testing as necessary, including demonstrating that

- c the main valve will fully close or fully open in a timely manner in the event of a partial open condition. tech issue 11 TECH ISSUE - PARTIAL OPEN The verification activities being performed by NuScale and Target Rock to demonstrate that a partial open failure mode of the ECCS valve is not credible need to be finalized as quality assurance products

- d that are available for NRC staff review. tech issue 12 TECH ISSUE - PARTIAL OPEN 2 - NuScale should describe its plans to resolve the safety questions regarding the potential partial open failure mode for the main valve of the ECCS valves to support the DC application. tech issue 13 TECH ISSUE - PARTIAL OPEN

- - IAB Valve Passive Component Assumption - - -

NuScale should justify its assumption that the guidance in Commission Paper SECY-94-084 (dated March 28, 1994), Policy and Technical Issues Associated with the Regulatory Treatment of Non-Safety Systems (RTNSS) in Passive Plant Designs, for categorizing a check valve in a new reactor as a passive component with respect to the single failure criterion is applicable to the spring-operated IAB valve 1 - in the NuScale reactor. - - -

NuScale should address the following technical aspects in resolving the safety questions regarding its assumption that the IAB valve may be categorized as a passive component with respect to the single 2 - failure criterion: - - -

The IAB valve has a different design from the pilot for the main steam safety relief valve (MSSRV), such that the MSSRV failure rate has not been demonstrated as applicable to the IAB valve without

- a significant operating or testing experience. tech issue 14 TECH ISSUE - IAB PASSIVE The IAB valve has multiple operating positions of initially open, close, and re-open in performing its safety functions while the NuScale response to RAI 8815 only evaluates a failure to close in calculating

- b the assumed failure rate for the IAB valve. tech issue 15 TECH ISSUE - IAB PASSIVE The low demand frequency assumed in the NuScale response to RAI 8815 to convert the failure rate of the IAB valve per demand to failure rate per year has not been justified in calculating the failure rate

- c of the IAB valve to satisfy the Commission paper guidance for passive components. tech issue 16 TECH ISSUE - IAB PASSIVE 3 - NuScale should describe the plans to demonstrate the reliability of the IAB valve to justify its consideration as a passive component with respect to the single failure criterion to support the DC application. tech issue 17 TECH ISSUE - IAB PASSIVE

- - NuScale Report ER-B020-6113 (Revision 0, dated January 26, 2018), ECCS Valve Subcomponent Level FMEA - - -

An FMEA is performed to identify potential failure modes of a new component design and to enable the design process to avoid the significant failure modes of the component. An FMEA prioritizes the significance of the potential failure modes by calculating a Risk Priority Number (RPN) for each failure mode by the multiplication of assigned Severity, Occurrence and Detection rating numbers. Based on the FMEA results, the potential failure modes with the highest priority RPNs are specified for corrective action as part of the design process or other activities to address those significant failure modes.

NuScale Report ER-B020-6113 (Revision 0, dated January 26, 2018), ECCS Valve Subcomponent Level FMEA, forwards the FMEA of the NuScale ECCS valves performed by Target Rock. The FMEA for 1 - the NuScale ECCS valves indicates an RPN of 200 as the significance level for potential failure modes without justifying the RPN methodology. simple fix 18 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the various approaches that could be applied in performing the FMEA for the NuScale ECCS valves. For example, Update FMEA for basis of cut-off level of some approaches assign the top 20% of the RPNs as failure modes that will be addressed for corrective action. The FMEA should specify the basis for the selection of 200 for the significant RPN level in significant and what further actions are or are

- status light of many failure modes that approach the 200 level. simple fix 18 not required for items above the cut-off NuScale Nonproprietary

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NuScale ECCS Valve FMEA Audit Folow-Up Item Attachment 2

Classification Report Page  of 10

1. sub Subject/Item Category Index NRC Notes The FMEA report describing the categorization of potential failure modes of the ECCS valves and their four valve subcomponents identifies the IAB valve bellows assembly and the potential for debris to damage operational clearances as the most significant risk items in that their RPNs are calculated to be 200 or above. The FMEA report states that partial open failures were considered for the ECCS main valve. The FMEA indicates that several components in the main valve body were postulated as a risk of causing a partial open failure if they are damaged or entrained with debris. Other components outside of the main valve (such as the IAB valve, hydraulic line, and trip valve) were said to have postulated failures that could cause inadvertent opening of the main valve. The FMEA report concludes that no credible component failures were identified that would cause inadvertent opening or failure of the main valve to a partial open state. The FMEA report also notes that boric acid crystallization is a 2 - phenomenon that might affect the function of the valve system. The FMEA does not include plans to address these failure modes as part of the design process. simple fix 19 See next row During the onsite audit, the NRC staff discussed the conclusions of the FMEA with NuScale and Target Rock personnel. NuScale should describe the plans to address the FMEA report conclusions to

- status demonstrate the safety features of the ECCS valves and their valve subcomponents to support the DC application. simple fix 19 Update FMEA In addition to the failure modes indicated in the FMEA report conclusions, the FMEA report identifies several failure modes that approach the RPN significance level of 200 (such as in Table 6-7). Minor uncertainty adjustments to the assignment of Severity, Occurrence, and Detection rating numbers for several failure modes would cause the RPN for those failure modes to approach or exceed the RPN 3 - significance level. An FMEA is intended to identify the significant failure modes for corrective action as part of the design process or other activities to avoid those failure modes. simple fix 20 See next row Update FMEA for basis of cut-off level of During the onsite audit, the NRC staff discussed potential failure modes that approach the assigned 200 RPN significance level with NuScale and Target Rock personnel. NuScale should describe the plans significant and what further actions are or are

- status to resolve the significant failure modes for the ECCS valves identified by the FMEA, including consideration of the uncertainties in the rating numbers, to support the DC application. simple fix 20 not required for items above the cut-off The FMEA should identify the applicable mitigating factors to support the assigned Severity, Occurrence, and Detection rating numbers used in calculating the RPN for each failure mode. Several failure modes in the FMEA tables do not specify mitigating factors. For example, failure mode 6-7-9 in Table 6-7 for IAB disc failure does not provide the mitigating factors for the assigned Severity, Occurrence, and Detection rating numbers. In addition, some tables specify general mitigating factors that are not appropriate to address the specific potential failure mode in the new ECCS valve design. For example, failure mode 6-2-1 lists the redundant main valves and passive low pressure opening of the main valve when the RPV pressure is within approximately ((-)) pounds per square inch differential (psid) of the containment vessel (CNV) pressure. Failure mode 6-2-2 specifies the high reliability passive design as the mitigating factor. In addition, failure mode 6-3-1 references qualification as a mitigating factor, 4 - which is not a design factor. simple fix 21 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the absence of mitigating factors or the specification of general mitigating factors for many potential failure modes identified in the FMEA. The staff indicated that the FMEA tables should specify the mitigating factors to support the calculated RPNs for the design of the ECCS valves. Itemized notes could be used to Update FMEA, add mitigating factors where

- status identify the mitigating factors that apply to several failure modes. simple fix 21 appropriate.

Several failure modes, such as 6-1-8, 6-3-2, 6-6-28, 6-6-52, 6-6-53, 6-7-4, 6-7-10, 6-8-4a, 6- 8-10, 6-8-14, 6-8-19, and 6-8-20, in the FMEA tables specify inservice or routine testing as part of the mitigating 5 - factors for those failure modes. The basis for these mitigating factors is not clear in the FMEA. simple fix 22 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the references in the FMEA to inservice or routine testing as mitigating factors for potential failure modes. Based Update FMEA, add reference to PST/IST

- status on the FMEA results, NuScale should verify that the plans for preservice testing (PST) and inservice testing (IST) are applicable for the mitigation of the specified failure modes. simple fix 22 where appropriate.

6 - FMEA Table 5-1 (Severity), Table 5-2 (Occurrence), and Table 5-3 (Detection) assign rating numbers of 1 to 10 for potential failure modes. Comments on the specific tables are as follows: - - -

- - Table 5-1, Severity (S) - - -

- a Table 5-1 assigns a Severity rating number of 5 for inadvertent/spurious opening of the main valve. resolved 23 -

During the onsite audit discussions, NuScale personnel clarified that inadvertent opening of the main valve was considered a mid-range 5 severity because it does not directly challenge the reactor fuel. The

- status NRC staff considered this clarification to be acceptable. resolved 23 -

- b Table 5-1 assigns a Severity rating number of 5 for failure of the IAB function. simple fix 24 See next row During the onsite audit discussions, NuScale personnel indicated that the mid-range severity number of 5 was assigned because the IAB valve is normally open. NuScale personnel stated that a severity of

- status 8 to 10 would be applied for the potential failure of the IAB valve to re-open. The FMEA should clarify this difference in severity ratings for the appropriate functions of the IAB valve. simple fix 24 Update FMEA

- c Table 5-1 assigns a Severity rating number of 6 for slow opening (est > 10 s, to 60 s) of the main valve. resolved 25 -

During the onsite audit discussions, NuScale personnel clarified that slow opening of the main valve was not a severe event because of the slow progression of core uncovery. The NRC staff considered this

- status clarification to be acceptable. resolved 25 -

- - Table 5-2, Occurrence (O) - - -

Table 5-2 assigns Occurrence levels (and their rating numbers) as Not Credible (1), Remote (2 or 3), Moderate (4, 5, or 6), High (7 or 8), and Very High (9 or 10). However, the examples do not differentiate

- a between these multiple rating numbers. simple fix 26 See next row During the onsite audit discussions, Target Rock personnel indicated that engineering judgment was applied to distinguish between events in the same Occurrence level. The FMEA should specify the basis

- status for the assignment of rating numbers for each Occurrence level in calculating the applicable RPN where Table 5-2 does not differentiate between the specific rating numbers. simple fix 26 Update FMEA

- b Table 5-2 defines the Remote Occurrence level as failures that may have been reported in relevant developmental testing, but not in service, with examples of bolt breakage or broken wires. resolved 27 -

During the onsite audit discussions, Target Rock personnel clarified that the operating experience with solenoid valves was applied in assigning the Remote Occurrence level to specific potential failure

- status modes. The NRC staff considered this clarification to be acceptable. resolved 27 -

tech issue, minor.

- c Table 5-2 does not discuss potential failures related to the loss of power to the trip and reset valves. Provide response 28 See next row During the onsite audit discussions, Target Rock personnel indicated that the FMEA did not address loss of power or tubing performance because these aspects of the ECCS valve design are within the specific NuScale technical areas. NuScale should supplement the FMEA as necessary to address potential failure modes in technical areas not addressed by Target Rock (such as loss of power and tubing tech issue, minor. TECH ISSUE - NON-VALVE FAILURE

- status performance). Provide response 28 MODES EVAL (power/tubing)

- - Table 5-3, Detection (D) - - -

Table 5-3 assigns Detection levels (and their rating numbers) as Monitored (1), Detectable (2 or 3), Potential (4, 5, or 6), Late (7 or 8), and None (9 or 10). However, the examples do not differentiate

- a between these multiple rating numbers. simple fix 29 See next row

- status The FMEA should specify the assignment of rating numbers for each Detection level in calculating the applicable RPN where Table 5-3 does not differentiate between the specific rating numbers. simple fix 29 Update FMEA Table 5-3 assigns Detection rating numbers of 4 through 8 based on inservice inspection (ISI), IST and/or PST. If ISI and IST are only conducted during refueling outages every 2 years, ISI and IST will only

- b detect some performance aspects prior to failure. Similarly, PST is only conducted prior to placing the valve in service. simple fix 30 See next row NuScale Nonproprietary

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NuScale ECCS Valve FMEA Audit Folow-Up Item Attachment 2

Classification Report Page  of 10

1. sub Subject/Item Category Index NRC Notes During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the need to link the FMEA results with planned IST and ISI activities. NuScale should justify the Detection rating

- status numbers for the specific failure modes based on whether the planned ISI, IST, or PST will detect the failure mode prior to its occurrence. simple fix 30 Update FMEA NuScale indicated that some design aspects of the safety features of the ECCS valves are planned to be addressed during qualification testing by the combined license (COL) holder. These include, for example, (1) the impact of flashing of the reactor coolant in the four valve subcomponents of the ECCS valves, (2) the establishment of the proper shim at the factory to provide assurance that the IAB spring will close and then re-open at the proper differential pressure between the reactor coolant system and containment vessel, and (3) the impact of boric acid on the four valve subcomponents of the ECCS valves. Design proof-of-performance testing by a DC applicant and component qualification testing by a COL holder are two separate activities. Specifically, design testing required by 10 CFR 52.47(c)(2) and 50.43(e) involves testing sufficient to demonstrate that a new design feature, which in this case is a new valve design, can perform its safety functions. Such testing may include a repetitive series of tests of an initially proposed valve design with modifications made to the valve design based on multiple test results until the necessary performance has been successfully demonstrated. In contrast to design testing, qualification testing involves testing to verify that the valves as procured for installation in the facility are capable of performing their specific safety functions as indicated in the Final Safety Analysis Report (FSAR). Qualification testing does not generate design information at the FSAR level of detail needed for design certification; rather, qualification testing is a special treatment activity under 10 CFR Part 50, Appendix B, Criterion III, Design Control, and the requirements of the ASME Boiler and Pressure Vessel Code (BPV Code),Section III, among other NRC requirements for the design, manufacture, and installation of certain systems and components in a particular nuclear power plant. Qualification testing is not intended to provide proof-of-performance for new safety features or develop a first-of-a-kind prototype valve. Valve failure during qualification testing would result in an extent-of-condition evaluation of the design control process to identify the root cause of the failure and appropriate corrective action to resolve the specific valve failure and the discrepancy in the design control process. Such failure would not normally indicate that the high-level valve design was inadequate (thus requiring modification of the certified design by rulemaking); rather, failure during qualification testing normally indicates that the particular valve, as procured in accordance with its design specification, 7 - did not perform as designed (e.g., the valve did not meet its design specification or included a latent manufacturing flaw). simple fix 31 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the importance of determining those design aspects to be verified for the DC application and those performance Update FMEA, clarify where credit is being aspects that can be addressed as part of qualification activities by the COL holder. NuScale should describe the plans to resolve the design aspects of the safety features of the ECCS valves to support the taken for qualification testing vs. design

- status DC application. simple fix 31 performance.

- - Potential Failure Modes and Reliability Not Addressed in FMEA - - -

The FMEA report does not include an evaluation of the timeliness of the IAB valve function to initially close against a large spring force to isolate the main valve control chamber and then open at the 1 - appropriate differential pressure between the RPV and CNV to provide for the proper operation of the main disc of each ECCS valve. tech issue 32 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the importance of the IAB valve to close promptly to avoid inadvertent opening of the main valve disc at high reactor pressure, and then to re-open at the proper pressure conditions to allow the main valve control chamber to depressurize such that the main valve disc will open to allow natural circulation to begin for reactor core cooling. NuScale should describe the capability of the IAB valve to meet its operating requirements in support of the DC application, and testing that is available to demonstrate IAB valve

- status performance. tech issue 32 TECH ISSUE - POC TESTING The FMEA report does not include an evaluation of the sizing of the IAB valve seat, trip valve, and the connecting tubing to provide for the depressurization of the main valve control chamber in a timely 2 - manner. tech issue 33 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the importance of the sizing of the IAB valve seat, trip valve, and the connecting tubing to provide for the depressurization of the main valve control chamber in a timely manner. Target Rock personnel provided spreadsheet calculations that support the proposed sizing of these components, with plans to verify the calculations using actual test data. NuScale should describe the plans to verify the calculations for the sizing of the IAB valve seat, trip valve, and the connecting tubing to support the safety features of TECH ISSUE - VALVE SYSTEM

- status the ECCS for the DC application. tech issue 33 OPERATION AT OPERATING CONDITIONS The FMEA report does not include an evaluation of the potential for boric acid precipitation and crystallization, as well as flashing of reactor coolant, to impact the performance of the ECCS valve and its 3 - subcomponents, with consideration of the small clearances of the tubing and valve seats. tech issue 34 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the potential for boric acid precipitation and crystallization, as well as flashing of the reactor coolant, to impact the performance of the ECCS valve and its subcomponents. Target Rock personnel did not consider the boric acid to have an adverse effect on the clearances based on experience with other valves under high temperature conditions. NuScale personnel stated that the potential impact of the low temperature conditions in the containment pool is being considered. NuScale should describe the plans to demonstrate TECH ISSUE - VALVE SYSTEM

- status that boric acid precipitation and crystallization and flashing of reactor coolant will not impact the safety features of the ECCS valve to support the DC application. tech issue 34 OPERATION AT OPERATING CONDITIONS The FMEA report does not address the potential failure mode related to borated liquid reactor coolant in the control chamber of the main valve and its effect on the operation and position of the main valve 4 - disc upon opening of the trip valve when a pressure drop occurs in the main valve control chamber prior to the IAB valve closing. tech issue 35 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the potential failure mode related to borated liquid reactor coolant in the control chamber of the main valve and its effect on the operation and position of the main valve disc upon opening of the trip valve when a pressure drop occurs in the main valve control chamber prior to the IAB valve closing. Target Rock personnel prepared preliminary calculations that predicted that the main valve might fully open or might re-close following a partial opening depending on the specific reactor conditions. NuScale and Target Rock personnel do not believe that the main valve disc could stabilize in a partial open condition. NuScale should describe the plans to demonstrate the performance of the main valve disc as a result of the

- status pressure drop in the main valve control chamber upon initial opening of the trip valve to support the DC application. tech issue 35 TECH ISSUE - PARTIAL OPEN The FMEA report does not include an evaluation of the performance of the main disc with a small orifice and filter between the liquid borated reactor coolant in the main valve control chamber and steam in 5 - the pressurizer to transmit pressure of the borated reactor coolant for the intended valve performance. tech issue 36 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the performance of the main disc with a small orifice and filter between the liquid borated reactor coolant in the main valve control chamber and steam in the pressurizer to transmit pressure of the borated reactor coolant for the intended valve performance. Target Rock personnel indicated that the orifice sizing will be based on analytical and historical experience with valves (such as safety relief valves). NuScale should describe the plans to demonstrate the performance of the main disc with the proper sizing of the TECH ISSUE - VALVE SYSTEM

- status orifice and filter for the safety features of the ECCS valve to support the DC application. tech issue 36 OPERATION AT OPERATING CONDITIONS tech issue, minor.

6 - The FMEA report does not address the potential impact of the reverse flow from the diffuser upon actuation of the RVV. Provide response 37 See next row As indicated in the comments on the RVV Diffuser report, NuScale should describe its plans to demonstrate the performance of the RVVs in response to the reaction flow from the diffuser to support the DC tech issue, minor.

- status application. Provide response 37 TECH ISSUE - DIFFUSER REVERSE FLOW The FMEA report does not address the recirculation flow requirement of the RRVs to perform their safety function to allow condensed reactor coolant to enter the RPV from the CNV with sufficient flow to 7 - cool the reactor core in a timely manner. simple fix 38 See next row Update FMEA to point to document which As indicated in the comments on the ECCS Qualification Plan, NuScale should describe the plans to demonstrate the safety feature of the RRVs to provide recirculation flow for core cooling to support the include flow requirements (Cv, Xt) for

- status DC application. simple fix 38 recirculation.

tech issue, minor.

8 - The FMEA report addresses a potential tubing break, but does not discuss other potential failure modes of the tubing, such as binding or crimping. Provide response 39 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the potential failure modes related to binding or crimping of the tubing. This issue was identified as a NuScale tech issue, minor. TECH ISSUE - NON-VALVE FAILURE

- status evaluation item. NuScale should describe its plans to demonstrate the design of the ECCS valves to avoid adverse effects of binding or crimping of the valve tubing to support the DC application. Provide response 39 MODES EVAL (power/tubing)

NuScale Nonproprietary

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1. sub Subject/Item Category Index NRC Notes NuScale assumes that the ECCS valve is a passive component with respect to the single failure criterion for such design aspects as IAB valve performance and partial opening of the main valve disc.

Commission Paper SECY-94-084 indicated that check valves in new reactors with passive cooling systems might not be justified as passive components, because the driving head to open check valves in passive cooling systems might rely on gravity rather than pump flow. SECY-94-084 specified that a failure probability on the order of 1E-4 per year or less would be low enough to be considered a passive 9 - failure. The FMEA report does not address the reliability of the ECCS valve with respect to the passive component assumption. no action 40 See next row During the onsite audit, the NRC staff discussed with Target Rock and NuScale personnel the need to justify the assumption that the IAB valve is a passive component in the NuScale safety analysis.

- status Following the onsite audit, the staff conducted additional internal discussions. The staff position on the NuScale assumption for the IAB valve as a passive component is addressed in this audit report. no action 40 Covered by other items.

- - Table 6-1, Functional FMEA, Trip/Reset Valves - - -

- - The comments on Table 6-1 have been incorporated into other comments provided in this audit report. A few specific comments are provided below: - - -

Failure mode 6-1-1 relates to the potential spurious opening of the trip valve that would cause the main valve to open. The Occurrence rating number for this failure mode is specified as 2, which is indicated 1 - as remote in Table 5-2. no action 41 -

During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the potential spurious opening of the trip valve. Target Rock personnel considered that the potential spurious opening of the trip valve from mechanical causes is remote based on operational experience with solenoid valves. Target Rock personnel indicated that electrical aspects were not addressed in the FMEA as outside the Target Rock scope. NuScale should justify the basis for the remote failure assumption for the trip valves. The applicable NRC staff are evaluating the NuScale assumption for the reliability of

- status the trip valve circuitry. no action 41 -

Failure mode 6-1-2 relates to leakage of the trip valve that might cause the main valve to open. The mitigating factors refer to control room leak detection. NuScale indicated that the leakage detection referenced for this failure mode applies to general RPV leakage rather than specific trip valve leakage. NuScale indicated that procedures will provide for plant shutdown in response to significant RPV 2 - leakage. no action 42 -

- status The NRC staff will review the NuScale Technical Specification 3.4.5 for reactor operational leakage for consistency with the NuScale ECCS valve final design. no action 42 -

Failure mode 6-1-4 relates to the potential failure of the trip valve to open. The mitigating factors are specified as redundant RVVs and RRVs, and opening of the main valve by spring force when the tech issue, minor.

3 - pressure differential between the RPV and CNV reaches ((-)) psid. Provide response 43 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the design of the main valve to open with low differential pressure when the IAB valve blocks depressurization of tech issue, minor. TECH ISSUE - MAIN VALVE SPRING

- status the main valve control chamber. NuScale should describe its reliance on the main valve spring to support the safety function of the ECCS valves. Provide response 43 CREDIT FOR SAFETY Failure mode 6-1-7 relates to the potential rupture of the manifold providing the CNV boundary. The mitigating factors refer to hydrotesting in accordance with ASME Standard B16.34, Valves - Flanged, 4 - Welded, and Welding End. resolved 44 -

During the NuScale audit at the Target Rock facility, Target Rock personnel indicated that the ASME BPV Code requirements for the ECCS valve will be satisfied, including the reference to ASME B16.34.

- status This clarification is acceptable for this audit. resolved 44 -

5 0 Failure mode 6-1-8 relates to the failure of the gasket providing the CNV boundary. The FMEA states that there is no effect on the main valve. no action 45 -

- status The NRC staff is reviewing the design aspect of the ECCS valve with respect to the gasket providing the CNV boundary as part of RAI 9315, Question 03.08.02-14. no action 45 -

- - Table 6-2, Functional FMEA, IAB Valve - - -

- - The comments on Table 6-2 have been incorporated into other comments provided in this audit report. no action - -

- - Table 6-3, Functional FMEA, Main Valves - - -

- - The comments on Table 6-3 have been incorporated into the other comments provided in this audit report. no action - -

- - Table 6-4, Functional FMEA, Consideration of Partial Open Valve Failure - - -

- - The comments on Table 6-4 have been incorporated into other comments provided in this audit report. no action - -

- - Table 6-5, Functional FMEA, Consideration of Valve Failure Caused by Boric Acid - - -

- - The comments on Table 6-5 have been incorporated into other comments provided in this audit report. A few specific comments are provided below: - - -

Table 6-5 lists potential failure modes caused by boric acid. NuScale should provide justification that the lessons learned from the Davis Besse RPV degradation, such as described in NRC NUREG/BR-0353 (Revision 1), Davis-Besse Reactor Pressure Vessel Head Degradation, or documents prepared by the Institute of Nuclear Power Operations (INPO), have been addressed in the design of the ECCS tech issue, minor.

1 - valves, such as related to materials in failure mode 6-5-1. Provide response 46 See next row During the onsite audit, NuScale personnel indicated that the lessons learned related to boric acid effects from the Davis Besse event have been considered in its design of the ECCS valves. NuScale tech issue, minor. TECH ISSUE - ADDRESS DAVIS BESSE

- status should include its consideration of the Davis Besse lessons learned as part of its final design documentation. Provide response 46 LESSONS LEARNED tech issue, minor.

2 - Failure mode 6-5-13 relates to the main valve filter being blocked by boric acid precipitation and crystallization. The FMEA categorizes this potential failure mode as remote. Provide response 47 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the potential for the main valve filter to be blocked by debris. Target Rock personnel considered that such blockage would not have a significant effect on the capability of the main valve to open. NuScale should demonstrate that the blocking of the main valve filter is not credible for the ECCS valve to support the DC tech issue, minor. TECH ISSUE - VALVE INTERNAL FILTER

- status application. Provide response 47 PERFORMANCE

- - Table 6-6, Component FMEA, Actuator Valves (TRV and TV) - - -

- - The comments on Table 6-6 have been incorporated into other comments provided in this audit report. no action - -

- - Table 6-7, Component FMEA, IAB Valve - - -

- - The comments on Table 6-7 have been incorporated into other comments provided in this audit report. A few specific comments are provided below: no action - -

Failure modes 6-7-5, 6-7-6, 6-7-7, and 6-7-8 relate to potential failures of the IAB valve involving the bellows assembly, bellows retainer, bellows, and rod, respectively. NuScale indicated that these high 1 - RPN significance failure modes would be mitigated by the availability of pressure under the rod that will operate the IAB valve. simple fix 48 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the potential failure modes of the IAB valve involving the bellows assembly, bellows retainer, bellows, and rod. Update FMEA. Expand conclusions that no

- status NuScale should demonstrate that the ECCS valve will perform its safety function in consideration of these failure modes to support the DC application. simple fix 48 failure modes identified are unacceptable.

Failure mode 6-7-9 relates to the potential jamming of the IAB disc from wear or entrapped debris causing inadequate operation of the IAB valve and main valve. The FMEA does not specify the mitigating 2 - factors for this high RPN significant failure mode. simple fix 49 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the potential jamming for the IAB valve disc. NuScale should demonstrate the performance of the IAB valve disc to Update FMEA, add mitigating factors where

- status support the DC application. simple fix 49 appropriate.

Failure mode 6-7-11 relates to the leakage of the IAB O-ring causing increased time to vent control pressure and actuate the main valve. The FMEA does not specify mitigating factors for this high RPN 3 - significant failure mode. simple fix 50 See next row During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the performance of the IAB valve O-ring. NuScale should justify the performance of the IAB valve with respect to O- Update FMEA, add mitigating factors where

- status ring performance to support the DC application. simple fix 50 appropriate.

Failure mode 6-7-19 relates to inadequacy of the shim washer that is used to adjust the set pressure of the IAB valve. The Severity, Occurrence, and Detection rating numbers are specified as 1 for this 4 - failure mode. simple fix 51 See next row NuScale Nonproprietary

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1. sub Subject/Item Category Index NRC Notes Update FMEA, justify rating selection.

During the onsite audit, the NRC staff discussed with NuScale and Target Rock personnel the shim to be provided in the IAB valve. The shim is installed in the factory at nominal conditions to provide the Purpose of the shim is to allow adjustment, if proper set pressure for the IAB valve when operating in the reactor environment. Target Rock personnel indicated that the proper lift for hot conditions would be verified. NuScale should demonstrate that the required, based on future testing

- status shim installed in the factory will be appropriate in the reactor environment, such as the temperature differential, to support the DC application. simple fix 51 (qualification, PST/IST).

- - Table 6-8, Component FMEA, Main Valves - - -

- - The comments on Table 6-8 have been incorporated into other comments provided in this audit report. A few specific comments are provided below: - - -

Failure mode 6-8-5 relates to the potential jamming from wear or entrapped debris of the sleeve that allows axial movement of the main disc. The mitigating factor specifies a proven design with controlled 1 - clearances for operability under design conditions. tech issue 52 See next row During the onsite audit, the NRC staff discussed the potential jamming of the main valve with NuScale and Target Rock personnel. NuScale personnel stated that this mitigating factor relates to the Target Rock valve design and its analysis of appropriate clearances under various operating conditions. NuScale should demonstrate the capability of the main valve to open fully without jamming as part of the

- status resolution of the partial open failure mode. tech issue 52 TECH ISSUE - PARTIAL OPEN tech issue, minor.

2 - Failure mode 6-8-17 relates to the potential clogging of the filter assembly with debris that could cause inadvertent main valve opening. The FMEA specifies this failure mode as low significance. Provide response 53 See next row During the onsite audit, the NRC staff discussed the potential clogging of the filter assembly with NuScale and Target Rock personnel. NuScale should demonstrate the performance of the control orifice and tech issue, minor. TECH ISSUE - VALVE INTERNAL FILTER

- status filter for the safety function of the ECCS valves to support the DC application. Provide response 53 PERFORMANCE 3 - Failure mode 6-8-46 relates to the impact of the diffuser installed at the outlet of the RVVs. The FMEA assigns Severity, Occurrence, and Detection rating numbers of 1 for this failure mode. simple fix 54 See next row During the onsite audit, the NRC staff discussed the RVV diffuser with NuScale and Target Rock personnel. NuScale should verify that the evaluation of this failure mode and its rating is consistent with the

- status resolution of the comments on the RVV diffuser report in this audit report. simple fix 54 Update FMEA, justify rating selection.

- - NuScale Report ER-B020-6289, ECCS Valve Description - - -

Section 3.4 states that the diffuser for the RVV contains approximately ((-)) inch diameter holes to limit the outlet flow velocity and force of the flow stream on components in the vicinity of the RVV outlet.

1 - What are the plans to address the impact on the interior of the RVV and main valve control chamber? no action 55 -

During the onsite audit, NuScale and Target Rock personnel described the determination of the reaction load on the RVV caused by the flow through the holes in the diffuser. The specific comments on the

- status RVV diffuser are provided later in this audit report. no action 55 -

Section 3.7 describes the self-opening actuator feature at low pressure when the reactor pressure drops to ((-)) to ((-)) psi, such that the main valve return spring will open the valve without the need for trip 2 - valve de-energization. Does this also apply if the RPV is at high pressure and the differential pressure with the CNV is within ((-)) to ((-)) psid? simple fix 56 see next row During the onsite audit discussions, NuScale personnel stated that differential pressure is the correct parameter for the self-opening actuator feature. NuScale plans to correct this reference to reactor Revise ER-B020-6289 to reflect differential

- status pressure in the ECCS Valve Description report. simple fix 56 pressure tech issue, minor.

3 - Section 3.7.1 states that the main disc feed orifice filter has a large area to mitigate debris. What are the plans to demonstrate that the filter design is adequate? Provide response 57 see next row During the onsite audit discussions, NuScale personnel stated that the orifice filter for the main valve will be sized based on Target Rock experience with filters in nuclear service. NuScale personnel considered the RCS to be sufficiently pure to avoid filter problems. With respect to boron precipitation, NuScale personnel stated that the filter will be above the melting temperature of boron (approximately 330 °F) such that boron will not block the filter. NuScale personnel discussed the plan to flush the main valve orifice filter with the chemical volume and control system (CVCS) prior to plant startup with reliance on the purity of the CVCS fluid to avoid filter problems. Based on the onsite audit discussions, NuScale should document its justification for the performance of the main valve orifice filter to support tech issue, minor. TECH ISSUE - VALVE INTERNAL FILTER

- status the NuScale DC application. Provide response 57 PERFORMANCE 4 - Section 3.7.1 discusses the connecting tubing. What are the volumes of the connecting tubing for the RVV and RRV? no action 58 -

During the onsite audit discussions, NuScale personnel stated that the volume of the RVV tubing is ((-)) in3 and the volume of the RRV tubing is ((-)) in3. NuScale personnel indicated that the water volume is

- status important to confirm the proper opening time for the applicable ECCS valve. The staff discusses the remaining issues regarding the applicability of the water volume for the POC testing in this audit report. no action 58 -

5 - Figure 4, Main Valve Cross-Section, includes an adjusting nut. What is the purpose of this nut and when can it be adjusted? resolved 59 -

During the onsite audit discussions, NuScale personnel clarified that the adjusting nut in the main valve drawing is used for manufacturing adjustments rather than installed adjustments. The NRC staff

- status considers this clarification of the function of the adjusting nut to be acceptable for this audit. resolved 59 -

Section 3.10 states that when the trip valve is activated, a small amount of control pressure will be vented before the IAB valve closes. What are the plans to demonstrate that the IAB will close promptly to 6 - prevent the main valve control chamber from losing sufficient pressure to allow the main valve to partially or full open? no action 60 -

The remaining issues regarding the demonstration that the IAB valve will close promptly to prevent the main valve control chamber from losing sufficient pressure to allow the main valve to partially or fully

- status open are discussed in this audit report. no action 60 -

Section 3.10 states that upon initial trip valve opening, the slight loss of control pressure will recover and will equalize with reactor pressure. If the main valve control chamber loses sufficient pressure to 7 - allow partial opening of the valve, will the control pressure recover and reclose the valve? no action 61 -

- status The remaining issues regarding the performance of the main valve if the control chamber loses sufficient pressure to allow partial opening of the valve are discussed in this audit report. no action 61 -

8 - Section 3.10 states that the IAB valve setpoint is adjusted by bellows rod adjustment in the IAB disc and by shimming the spring. How and when can these adjustments be made? simple fix 62 see next row Update FMEA, justify rating selection.

Purpose of the shim is to allow adjustment, if During the onsite audit discussions, NuScale personnel stated that these adjustments can only be made during the manufacturing process. NuScale should confirm that the ECCS valve design can required, based on future testing

- status accommodate appropriate adjustments during the manufacturing process for applicability to the reactor conditions. simple fix 62 (qualification, PST/IST).

9 - Section 4.1.1 indicates that the RVV nozzle opening is ((-)) inches and the RRV nozzle opening is ((-)) inches. How do these dimensions compare to the detailed drawings for the RVV and RRV? resolved 63 -

During the onsite audit discussions, NuScale personnel clarified that the minimum flow area for the RVV is ((-)) inches and for the RRV is ((-)) inches as indicated in the latest design diagrams. The NRC staff

- status considers this clarification to be acceptable for this audit. resolved 63 -

tech issue, minor.

10 - Section 4.2.2 states that the TRV, TV, and main valve tubing is NuScale equipment. What are NuScales plans to demonstrate the performance of this tubing? Provide response 64 see next row During the onsite audit discussions, NuScale personnel stated that the ECCS valve tubing will be 304 Stainless Steel seamless piping of Class 1 category similar to reactor sample lines. NuScale personnel stated that tubing supports will be addressed later during the design process. NuScale should demonstrate the performance of the connecting tubing and supports for the ECCS valves to support the DC tech issue, minor. TECH ISSUE - NON-VALVE FAILURE

- status application. Provide response 64 MODES EVAL (power/tubing) 11 - Section 4.2.3 indicates that provisions for detection of coolant leakage from the TRV and TV bonnet gaskets will be provided. What are these provisions? simple fix 65 see next row During the onsite audit discussions, NuScale personnel stated that the detection of leakage from the TRV and TV bonnet gaskets will be performed upon assembly. NuScale personnel also noted that Update FMEA, clarify these are test ports for

- status Appendix J testing will be performed every refueling outage. NuScale should complete its justification for leakage detection to satisfy the applicable NRC staff review for the DC application. simple fix 65 App J testing, not active leakage monitoring.

NuScale Nonproprietary

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1. sub Subject/Item Category Index NRC Notes 12 - Section 4.4 indicates that the main valve has two open switches and 2 closed switches for position indication. Do these switches indicate partial main valve positions, or only fully open and closed? resolved 66 -

During the onsite audit discussions, NuScale personnel stated that the position indication switches only indicate full open or full closed positions of the main valve. The NRC staff considers this clarification

- status to be acceptable for this audit. resolved 66 -

Section 4.4 discusses the prototype development for the main valve position switch that needed design changes based on performance degradation from high temperature conditions. What is the status of 13 - the development of the prototype position switch? no action 67 see next row During the onsite audit discussions, NuScale personnel stated that an upgrade to the main valve position switch is being designed for high temperature applications. NuScale plans to test the upgraded main

- status valve position switch when available. NuScale should make available the results of the testing of the main valve position switch when completed. no action 67 Future activity 14 - The pdf files attached to Appendix B of the ECCS Valve Description Report do not open for viewing. resolved 68 -

During the audit close-out discussion on May 22, 2018, NuScale notified the NRC staff that the electronic reading room (eRR) does not allow for opening of the pdf files attached to Appendix B of the ECCS

- status Valve Description report. The NRC staff does not consider these pdf files to be essential for the DC application review. resolved 68 -

- - NuScale ER-B020-6052, ECCS RVV Diffuser Report - - -

In Section 4.1, Target Rock recommends that the design specification be changed to make the diffuser a separate item so as to not be installed during the pressure test. What are NuScale plans regarding 1 - the RVV diffuser as a separate item for testing? no action 69 -

During the onsite audit discussions, NuScale personnel stated that Revision 3 to the ECCS Valve Design Specification will address the evaluation of the RVV diffuser as a separate item for testing. The

- status NRC staff will confirm this provision for the RVV diffuser during the review of the ECCS Valve Design Specification as part of the follow-up audit of the NuScale design specifications. no action 69 -

In Section 4.3, Target Rock indicates that there is a significant change in density between the main valve section and outlet section resulting in sonic velocity at the outlet with choked flow and higher 2 - pressure drop through the diffuser. What are NuScale plans to address this performance attribute? simple fix 70 see next row Update ER-B020-6052 to indicate that the During the onsite audit discussions, NuScale personnel stated that this performance attribute will be demonstrated by analysis with testing if necessary. NuScale should make this demonstration available overall flow requirements (Cv, xT) for the

- status for NRC staff review. simple fix 70 RVV account for effects through the diffuser.

3 - Section 4.3 indicates that a nonsafety-related computational fluid dynamics (CFD) analysis was applied to cross-check the hand calculations. How was the CFD analysis verified to be acceptable? simple fix 71 see next row Update ER-B020-6052 to indicate that CFD was used for an information only review of flow distribution. The fundamental thrust load requirement to be analyzed is provided in the design spec (EQ-B020-2140) which significantly bounds those results and does not take any credit for the presence of the During the onsite audit discussions, Target Rock personnel indicated that the nonsafety-related CFD analysis was applied only for information purposes. This issue was identified during the NRC vendor diffuser. The valve passes stress limits with

- status inspection conducted at the same time as the onsite audit. NuScale should address any appropriate actions based on the Target Rock response to the NRC vendor inspection findings. simple fix 71 the bounding design spec thrust.

Table 3 indicates that the spherical end of the diffuser will pass ((-))% of the total mass flow with ((-))% of the flow area while straight section of the diffuser will pass ((-))% of the total mass flow with ((-))% of 4 - the flow area. How will this estimation be verified? simple fix 72 see next row CFD was used for an information only review of flow distribution. The fundamental thrust load requirement to be analyzed is provided in the design spec (EQ-B020-2140) which significantly bounds those results and does not take any credit for the presence of the During the onsite audit discussions, Target Rock personnel indicated that the estimation of mass flow through the spherical end of the diffuser was obtained from the CFD analysis. This issue was identified diffuser. The valve passes stress limits with during the NRC vendor inspection conducted at the same time as the onsite audit. NuScale should address any appropriate actions based on the Target Rock response to the NRC vendor inspection the bounding design spec thrust. Update

- status findings. simple fix 72 document to clarify.

5 - Table 4 and Appendix C provide the CFD results for low pressure conditions. Were high pressure conditions evaluated? resolved 73 -

During the onsite audit discussions, Target Rock personnel clarified that the CFD analysis was not performed for high pressure conditions. The NRC staff considers this clarification to be acceptable for this

- status audit. resolved 73 -

Section 4.4 specifies that the reaction force calculation is based on ASME BPV Code, Appendix O, Rules for Design of Safety Valve Installations. Paragraph O-1230, Other Mechanical Loads, specifies 6 - consideration of the transient impacting the valve mechanism. How has NuScale addressed this provision? no action 74 see next row During the onsite audit discussions, the NRC staff described the provisions in paragraph O-1230 of Appendix O to the ASME BPV Code. Target Rock personnel indicated that the potential effects on the valve mechanism from the reaction forces created by the turbulent flow in the RVV diffuser will be addressed as part of the final design. As a follow-up to this discussion, Target Rock personnel provided Future action. This consideration will be in the initial calculations predicting that the applied load from ((-)) psid differential pressure on the main valve disc would not exceed the allowable stress at the orifice region. NuScale should demonstrate the design report. Stem/disc side loading due to

- status design capability of the RVV valve mechanism when the valve design is complete. no action 74 flow is addressed in partial open subject.

7 - Figure 5 indicates the orientation of the installation of the RVVs on the pressure vessel head. How is the torque moment during RVV discharge addressed? no action 75 see next row During the onsite audit discussions, Target Rock personnel stated that the torque moment during the RVV discharge will be addressed in the ASME Design Report. NuScale should confirm that this No action required at this time, this is a

- status evaluation is included in the completed ASME Design Report. no action 75 requirement in the design specification.

8 - Appendix B to the report describes the reaction load calculation. How will this reaction load calculation be verified? no action 76 see next row The required thrust load to be analyzed is During the onsite audit discussions, Target Rock personnel stated that the design will include this reaction load plus an additional safety margin. NuScale should confirm that the final design for the ECCS provided by NuScale in the valve design

- status valves includes the justification for the reaction load calculation for the RVV diffuser. no action 76 specification (EQ-B020-2140).

- - NuScale ER-B020-6117 (Revision 0, dated March 27, 2018), ECCS Valve Qualification Plan - - -

NuScale Nonproprietary

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1. sub Subject/Item Category Index NRC Notes Section 2.0 in the Qualification Plan specifies that the demonstration of ECCS valve functionality shall use analysis, testing, or a combination of both. ASME Standard QME-1-2007, Qualification of Active Mechanical Equipment Used in Nuclear Power Plants, Subarticle QV- 7100, General Requirements, states that Section QV, Functional Qualification Requirements for Active Valve Assemblies for Nuclear 1 - Power Plants, provides for qualification of a valve assembly by a combination of testing and analysis. NuScale should ensure that Section QV provisions are met in the qualification of the ECCS valves. simple fix 77 see next row

- status Based on discussions during the onsite audit, NuScale plans to update the Qualification Plan and also check the Design Specifications to verify that the language is consistent with ASME QME-1-2007. simple fix 77 Revise ER-B020-6117 to match QME-1 Section 2.0 in the Qualification Plan when discussing ASME QME-1-2007, Subarticle QV- 7300, Specific Qualification Requirements for Valve Assemblies, states that the ECCS valves are QME Category B such that end load testing are not applicable. QME Category A valves are defined as valves that isolate a blowdown transient. ASME QME-1-2007 was prepared prior to the development of reactor designs that use valves to create a reactor blowdown to reduce RCS pressure to allow passive gravity cooling of the reactor core. Similar to squib valves in the AP1000 reactors, the qualification of the 2 - NuScale ECCS valves needs to address the blowdown loads to demonstrate their performance capability. no action 78 -

- status Based on discussions during the onsite audit, NuScale plans to verify that the effects of the blowdown transient are addressed as part of the design of the ECCS valves. no action 78 -

Section 2.0 in the Qualification Plan when discussing ASME QME-1-2007, Subsubarticle QV-7410, Initial Considerations, states that the ECCS valves are unidirectional. NuScale should address the 3 - qualification of the dual direction performance of the RRVs. simple fix 79 see next row During the onsite audit discussions, Target Rock personnel indicated that the unidirectional specification is intended to require a specific orientation for installation. Target Rock personnel stated that this Revise document to clarify as indicated in the

- status language will be clarified in the Qualification Plan. The NRC staff finds this plan to be acceptable for this audit. simple fix 79 comment Section 2.0 in the Qualification Plan when discussing ASME QME-1-2007, Subsubarticle QV-7420, Environmental and Aging, for the environmental and aging qualification of the pilot valves states that testing has been performed on a solenoid valve essentially identical to the trip and reset valves used in the NuScale ECCS valve. NuScale should provide additional direction for the justification that the 4 - environmental and aging qualification of the essentially identical solenoid valve is applicable to the trip and reset valves. resolved 80 -

During the onsite audit discussions, Target Rock personnel indicated that the Application Report for each ECCS valve will include the details to justify application of the environmental and aging qualification

- status from similar valves. The NRC staff considers this response to clarify the intent of this provision in the Qualification Plan. resolved 80 -

Section 2.0 in the Qualification Plan when discussing ASME QME-1-2007, Subsubarticle QV-7450, Seismic Qualification, states that the main valve has no extended structure similar to self-actuated valve 5 - such that seismic testing is not required by QME-1. NuScale should provide additional justification to support the consideration that the main valve does not have an extended structure. resolved 81 -

Based on the onsite audit discussions, NuScale plans to include the justification for considering the main valve to not have an extended structure in the Application Report in accordance with ASME QME - status 2007. The NRC staff considers this plan to be acceptable for this audit. resolved 81 -

Section 2.0 in the Qualification Plan when discussing Subsubarticle QV-7450 for the main valve states that a seismic test is not required. NuScale should ensure that the qualification plan addresses 6 - dynamic qualification of the ECCS valve in accordance with the provisions in ASME QME-1-2007, Paragraph QR-7312, Dynamic loading. resolved 82 -

Based on the onsite audit discussions, NuScale plans to clarify that dynamic loading as required by Paragraph QR-7312 in ASME QME-1-2007 for flow path and potential resonance response will be

- status addressed as part of the Qualification Plan. The NRC staff considers this plan to be acceptable for this audit. resolved 82 -

Section 2.0 in the Qualification Plan when discussing Subsubarticle QV-7450 for the pilot valves states that seismic qualification will be performed by a seismic test with a static load applied at the center of gravity of the extended operator structure as allowed per IEEE 344, Recommended Practices for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations. NuScale should ensure that the qualification plan provides assurance for the following: (a) the static load is applied along the least rigid axis, and (b) the static load is applied at the center of gravity of the extended structure.

QME Case QME-007, Alternative Methods for Seismic Qualification of Power-Actuated and Relief Valve Assemblies, and ASME QME-1-2017, Qualification of Active Mechanical Equipment Used in 7 - Nuclear Facilities, provides additional guidance on the use of static side load testing for seismic qualification of valves. simple fix 83 see next row Based on the onsite audit discussions, NuScale plans to clarify the Qualification Plan for seismic qualification of the pilot valves using a static side load test. The NRC staff considers this plan to be Update qualification plan as indicated in the

- status acceptable for this audit. simple fix 83 comment Section 3.0 of the Qualification Plan in Sequence 3 specifies that the main valve and the IAB valve will each undergo 750 cycles separately. NuScale should address the performance of the main valve and 8 - IAB valve to satisfy the 1E-4 per year failure rate to support the passive component assumption with respect to the single failure criterion. no action 84 -

- status During the onsite audit discussions, NuScale personnel referenced the responses to RAI 8815 for justification to consider the IAB valve as a passive component. This item is discussed in this audit report. no action 84 -

Section 3.0 of the Qualification Plan in Sequences 3, 4, and 7 indicates that seat lapping is allowed during the qualification process. NuScale should provide guidance that the seat lapping must not impact 9 - the capability of the main valve, IAB valve, or trip and reset valves to perform their safety functions to maintain an acceptable seat seal. simple fix 85 see next row Based on the onsite audit discussions, NuScale plans to provide additional guidance in the Qualification Plan regarding the acceptable frequency of seat lapping during the qualification testing. The NRC Update qualification plan as indicated in the

- status staff considers this plan to be acceptable for this audit. simple fix 85 comment Section 3.0 of the Qualification Plan in Sequence 8a, b, and c specifies high and low pressure performance of the main valve. NuScale indicated that the IAB valve will be disabled during these tests.

10 - NuScale should address the performance of the IAB valve during high and low pressure performance tests. resolved 86 -

During the onsite audit discussions, NuScale clarified that Sequence 8 of the Qualification Plan applies only to the flow capability of the main valve. The NRC staff considers this clarification to be

- status acceptable for this audit. resolved 86 -

Section 3.0 of the Qualification Plan in Sequence 8a, b, and c specifies high and low pressure performance of the main valve. NuScale indicated that the fluid will be at the appropriate pressure and temperature conditions, but that the water will not be borated. NuScale will need to address the qualification of the ECCS valves for borated water conditions to address flashing and boron precipitation 11 - effects. no action 87 -

- status The demonstration of the capability of the ECCS valves to perform with reactor fluid conditions of high temperature and pressure and boration is discussed in this audit report. no action 87 -

Section 3.0 of the Qualification Plan in Sequence 8a indicates that a successful qualification flow will be less than the predicted flow. NuScale indicated that the minimum flow is addressed by Sequence 8b 12 - and c. NuScale should demonstrate that the minimum flow for adequate recirculation is provided by the qualification plan. resolved 88 -

During the onsite audit discussions, NuScale personnel clarified that the qualification testing will demonstrate the minimum flow performance for recirculation of the RRV will be addressed in Sequence 8b.

- status The NRC staff considers this clarification of the Qualification Plan to address minimum recirculation flow of the RRV to be acceptable for this audit. resolved 88 -

Section 3.0 of the Qualification Plan in Sequence 8b indicates that the RRV will be tested to demonstrate that the Cv flow coefficient criteria are satisfied. NuScale should complete its demonstration of the 13 - acceptability of the acceptable range of the Cv flow coefficient specified in Design Specification. resolved 89 -

During the onsite audit discussions, NuScale personnel clarified that the Qualification Plan in Sequence 8b will address the acceptability of the full range of the Cv flow coefficient for the RRV, including both

- status flow directions. The NRC staff considers this clarification of the Qualification Plan to be acceptable for this audit. resolved 89 -

Section 3.0 of the Qualification Plan in Sequence 8c indicated that the RVV will be tested with extrapolation of flow results to be justified by analysis to demonstrate that the flow is within the acceptable 14 - bounds. NuScale should provide guidance to justify the acceptable demonstration of the flow performance of the RVV to perform its safety function. no action 90 -

During the onsite audit discussions, NuScale personnel indicated that the extrapolation of flow results during the qualification of the RVV will be justified. The NRC staff notes that the QME-1 requirements for the extrapolation of valve qualification are provided in Paragraph QV- 7462, Extrapolation of Qualification to Another Valve Assembly. Therefore, the qualification of the valve assembly should be

- status described in the Functional Qualification Report in accordance with Subsubarticle QV-8310, Functional Qualification Report, in ASME QME-1-2007. no action 90 -

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1. sub Subject/Item Category Index NRC Notes Section 3.0 of the Qualification Plan in Sequence 10 describes the functional testing for the IAB valve over a range of hydraulic fluid conditions to be applied to both the RVV and RRV. NuScale will need to address the qualification of the IAB valves in the ECCS valves for borated water conditions to address flashing and boron precipitation effects. In addition, NuScale will need to address the qualification of 15 - application of the IAB valve tests for both the RVV and RRV. no action 91 -

During the onsite audit discussions, NuScale personnel stated that the qualification testing of the IAB valve will include high temperature and pressure water without boration. The demonstration of the

- status design capability of the IAB valve to support the DC review is discussed in this audit report. no action 91 -

The Qualification Plan does not discuss post-installation testing specified in ASME QME 2007, Subsubarticle QV-7470, Post-Installation Verification and IST Baseline, for the ECCS valves. NuScale 16 - should address its plans to satisfy the QV-7470 provisions. simple fix 92 see next row During the onsite audit discussions, the NRC staff described the post-installation testing requirements specified in Subsubarticle QV-7470 of ASME QME-1-2007. Based on those discussions, NuScale Update qualification plan as indicated in the

- status plans to address the post-installation testing requirements in the Qualification Plan. The NRC staff considers this planned update of the Qualification Plan to be acceptable for this audit. simple fix 92 comment Section 4.0 of the Qualification Plan concludes that the Qualification Plan is intended to demonstrate how Target Rock plans to demonstrate that the ECCS valves have been designed and qualified in accordance with the design specification and ASME QME-1 Standard. Based on the comments on the qualification of the subcomponents of the ECCS valves, NuScale should address the design 17 - demonstration testing of the ECCS valves to support the DC application. no action 93 -

- status This audit report indicates the remaining issues for the demonstration of the design of the ECCS valves to support the DC application. no action 93 -

The Qualification Plan should discuss plans for batch testing of individual parts of the ECCS valves, such as bellows, springs, tubing, rods, filters, and bolts, to provide reasonable assurance in their 18 - capability to perform the applicable design-basis functions. resolved 94 -

During the onsite audit discussions, Target Rock personnel stated that the individual parts will be demonstrated (such as by batch testing) before being included in qualification testing. The NRC staff

- status considers this clarification to be acceptable for this audit. resolved 94 -

- - Technical Manuals - - -

NuScale provided preliminary ASME design reports for the ECCS valves in its eRR during this audit. The NRC staff will review the ASME design reports in comparison to the final design features of the

- - ECCS valves during a future audit for any remaining follow-up items. no action - -

- - Preliminary ASME Design Reports - - -

NuScale provided preliminary ASME design reports for the ECCS valves in its eRR during this audit. The NRC staff will review the ASME design reports in comparison to the final design features of the

- - ECCS valves during a future audit for any remaining follow-up items. no action - -

- - Initial ECCS Valve Audit Report Follow-Up Items - - -

NuScale stated that the valve supplier (Target Rock) has conducted calculations and analyses to support the design and performance of the ECCS valves, including the main valve, IAB valve, trip valve, 1 - and reset valve. For example, NuScale stated that the Target Rock calculations and analyses include the following: - - -

sizing and flow capacity calculations for the ECCS main valve, including assumptions for set pressure, overpressure, temperature, flow rate, backpressure, flow coefficient (Cv), pressure drop ratio factor

- a (XT), and appropriate correction factors; - - -

- b force balance on the main disc during the stages of actuation; - - -

- c evaluation of the performance of the main valve with a control orifice and filter intended to allow the main chamber to achieve and maintain full reactor pressure condition during plant operation; - - -

- d evaluation of the temperature effects in the sizing of the four valve subcomponents of the ECCS valve from normal room temperature to the operating conditions of each subcomponent; and - - -

- e summary analysis report of the ECCS valve design. - - -

NuScale stated that the detailed design documentation is maintained at the valve supplier facility. The NRC staff plans to review the ECCS valve calculations and analyses at the valve supplier facility as

- - part of its evaluation of the design of the ECCS valve and its subcomponents. - - -

Finalize Target Rock flow/force balance During the onsite audit, the NRC staff discussed the calculations and documentation for the ECCS valves with NuScale and Target Rock personnel. Specific comments on the calculations and documents calculations as QA docs. This calc will be are provided in this audit report. NuScale should confirm that the Target Rock calculations and documentation are finalized as quality assurance products for the final design of the ECCS valves to support finalized as part of partial open technical

- status the DC application. tech issue 95 issue.

NuScale stated that the ECCS valve will be designed such that the main valve will move to its full open position in a timely manner upon actuation, and remain in the full open position throughout its required 2 - operation. The NRC staff will review the FMEA to evaluate the potential failure modes of the ECCS valve (including its four valve subcomponents) when made available by NuScale during a future audit. no action 96 -

- status During the onsite audit, the NRC staff discussed the FMEA with NuScale and Target Rock personnel. The staff indicates the remaining FMEA review items in this audit report. no action 96 -

NuScale Design Drawing NP12-00-B020-M-GA-2617, Reactor Vent Valve Drawing, identifies the RVV as Nominal Pipe Size (NPS) 5 with a ((-))-inch inlet diameter and a ((-))-inch discharge diameter.

NuScale FSAR Tier 2, Section 6.3, Emergency Core Cooling System, specifies the RVV as a 6-inch valve. NuScale Design Drawing NP12-00-B020-M-GA- 2650, Reactor Recirculation Valve Drawing, identifies the RRV as NPS 2 with a ((-))-inch inlet diameter and a ((-))-inch discharge diameter. NuScale FSAR Tier 2, Section 6.3 specifies the RRV as a 4-inch valve. The NRC staff will evaluate the 3 - differences between the FSAR descriptions and design drawings for the RVVs and RRVs. no action 97 -

During the onsite audit, the NRC staff discussed the current design of the RVVs and RRVs with NuScale and Target Rock personnel. The resolution of the design size of the RVVs and RRVs is indicated in

- status this audit report. no action 97 -

NuScale Design Drawings NP12-00-B020-M-GA-2617 and NP12-00-B020-M-GA-2650 specify a filter assembly installed in the orifice between the reactor coolant pressure and main valve control chamber 4 - for both the RVV and RRV, respectively. The NRC staff will evaluate the demonstration by NuScale that the filter assembly will not impact the capability of the RVV and RRV to perform their safety functions. no action 98 -

During the onsite audit, the NRC staff discussed the filter assembly in the main valve with NuScale and Target Rock personnel. The staff indicates the remaining review items related to the filter assembly in

- status this audit report. no action 98 -

NuScale Design Drawing NP12-00-B020-M-GA-2617 indicates a diffuser assembly is installed near the discharge of the RVV. NuScale stated that the full assembly, including the diffuser, will undergo design testing to demonstrate the performance of the ECCS valves. The NRC staff will evaluate the design test setup, performance, and results for the potential impact of the diffuser assembly on the 5 - performance of the ECCS valves. no action 99 -

During the onsite audit, the NRC staff discussed the RVV diffuser assembly with NuScale and Target Rock personnel. The staff indicates the remaining review items related to the RVV diffuser assembly in

- status this audit report. no action 99 -

NuScale stated that the design of the IAB valve is consistent with the description in the response to RAI 8815 (Question 15-2) provided in the NuScale letter dated July 21, 2017. The RAI response states that the top of the rod is kept off the vent line seat by the pressure of the fluid in the control chamber and the vent line. However, the rod appears to be maintained in the open position by the IAB spring force. The rod will move against the vent line seat when the differential pressure between the reactor coolant system and the vent line is sufficient to overcome the IAB spring force. The NRC staff will review 6 - the final design of the IAB valve for consistency with the description in the RAI response. no action 100 -

During the onsite audit, the NRC staff discussed the design of the IAB valve with NuScale and Target Rock personnel. The staff indicates the remaining review items related to the design of the IAB valve in

- status this audit report. no action 100 -

NuScale Nonproprietary

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1. sub Subject/Item Category Index NRC Notes NuScale stated that the ongoing detailed design evaluation of the IAB valve will provide reasonable assurance of the closure of the vent port in a timely manner to prevent the main valve chamber from losing pressure such that the main valve would open (fully or partially) prior to the differential pressure between the RPV and CNV being reduced to the specified value. The NRC staff will review the final 7 - design of the IAB valve for its performance characteristics during a future audit. no action 101 -

During the onsite audit, the NRC staff discussed the operation of the IAB valve with NuScale and Target Rock personnel. The staff indicates the remaining review items related to the performance of the IAB

- status valve in this audit report. no action 101 -

NuScale stated that the ongoing detailed design evaluation of the IAB valve will provide reasonable assurance of the sealing requirements for the vent port to prevent leakage from the main chamber prior to the differential pressure between the RPV and CNV being reduced to the assumed value for main valve opening. NuScale Drawing Document NP12-00-B020-M-GA- 5679, Inadvertent Actuation Block Drawing, identifies the IAB valve assembly as a Category A valve in accordance with the IST program requirements in the ASME Code for Operation and Maintenance of Nuclear Power Plants (OM Code).

NuScale stated that it will evaluate the IAB valve categorization in the NuScale IST Program to satisfy the ASME OM Code regarding leakage requirements. The NRC staff will review the final design of the 8 - ECCS valve (including the IAB valve) to support its IST categorization. simple fix 102 see next row During the onsite audit, the NRC staff discussed the sealing requirements of the IAB valve with NuScale and Target Rock personnel. The most recent design drawing of the IAB valve assembly has downgraded the leakage categorization of the IAB valve. Upon completion of the final design of the IAB valve, NuScale should confirm that the leakage categorization of the IAB valve is consistent with its Review ECCS component

- status performance requirements. simple fix 102 requirements/categorization in IST program NuScale stated that the orientation of the trip and reset valves for the RVVs and RRVs might not match the orientation indicated in NuScale FSAR Tier 2, Figure 6.3-3, Emergency Core Cooling System Valve and Actuator Hydraulic Schematic, on page 6.3-27. NuScale stated that the actual design will have the reset valve on the top of the assembly, and the trip valve on the bottom of the assembly, to 9 - allow gravity to assist in the operation of each valve. The NRC staff will verify this orientation in final design drawings of the NuScale ECCS valves. resolved 103 -

- status During the onsite audit, NuScale personnel clarified the planned orientation of the trip and reset valves for the RVVs and RRVs. The NRC staff considers this clarification to be acceptable for this audit. resolved 103 -

NuScale stated that the four ECCS valve subcomponents will not be designed to allow adjustments following installation. NuScale stated that shims will be installed in the ECCS valve to adjust its performance during pre-installation testing. NuScale Drawing Document NP12 B020-M-GA-5679 specifies that shims will be installed between the spring and disc to achieve the IAB threshold and IAB release pressures within the specification requirements. NP12 B020-M-GA-5679 specifies that the IAB threshold pressure will be set between ((-)) and ((-)) psid, and that the IAB release pressure will be set between ((-)) and ((-)) psid, at the factory. The NRC staff will review the design of the ECCS valves (including shims and their precision) to account for variations between pre-installation testing and 10 - normal operating conditions. simple fix 104 see next row Review if shim can be adjusted after delivery from vendor to accommodate pre-service or in-service observed conditions. Update During the onsite audit, the NRC staff discussed the shim to be included in each IAB valve with NuScale and Target Rock personnel. As part of the final design of the ECCS valves, NuScale should description in appropriate design document

- status demonstrate that the shims are capable of accounting for variations between pre-installation testing and normal operating conditions. simple fix 104 as necessary.

NuScale stated that only position indication of the main valve and trip/reset valves will be monitored to demonstrate the operational readiness of the ECCS valves. The NRC staff will review the design of the 11 - ECCS valves to provide reasonable assurance of operational readiness of the ECCS valves (including operation of the IAB valve). no action 105 -

During the onsite audit, the NRC staff discussed the position indication provisions for the main valve and trip/reset valves. NuScale personnel indicated that the position indication assembly for the main

- status valve is being upgraded to be able to perform at high temperature conditions. The upgrade of the main valve position indication assembly is discussed in this audit report. no action 105 -

NuScale stated that the trip/reset lines and control chamber of the ECCS main valve will be filled with borated water from the CVCS during initial setup prior to plant startup. When the trip valve is opened, hot borated water will flash to steam in the main control chamber, IAB valve, and trip line. The NRC staff will review the design of the ECCS valves to provide reasonable assurance that the flashing of hot 12 - borated water and boron deposits will not interfere with the reliability and timeliness of the operation of the NuScale ECCS valves. no action 106 -

During the onsite audit, the NRC staff discussed the performance of the ECCS valves with hot pressurized borated water with NuScale and Target Rock personnel. The staff indicates the remaining review

- status items related to the fluid conditions for the ECCS valves in this audit report. no action 106 -

The NRC staff reviewed NuScale Report ER-B020-3817 on proof-of-concept (POC) testing prepared by the valve supplier in 2015 and made available by NuScale during this initial audit. The test report stated that the testing demonstrated the viability of the ECCS valve design, and the expected operation of the disconnected pilot concept and the IAB feature, in this first-of-a- kind engineering (FOAKE) design for the ECCS valves. However, there were several significant differences between the configuration and conditions for the valves used in the POC testing and the ECCS valves. Some of the 13 - differences are as follows: no action - -

The main valve used for the POC testing was a 2-inch Y-pattern globe valve. In the original design information, the main valves for the NuScale RVVs are specified as 6-inch 90° globe valves and for the

- a RRVs are specified as 4-inch 90° globe valves in NuScale FSAR Tier 2, Section 6.3, and associated design drawings. no action 107 -

The valve configuration used for the POC testing included a main valve separate from the IAB valve. The IAB valve used for the POC testing was indicated to be fully representative of the design of the IAB valve for the ECCS valves. In that test configuration, the high pressure to simulate the reactor coolant system entered the IAB valve directly below the IAB rod. NuScale Design Drawing NP12-00-B020-M-

- b GA-5679 shows the IAB valve to be directly attached to the main valve with the reactor coolant system pressure to enter the IAB valve from the side to surround the rod bellows. no action 108 -

The trip valve used for the POC testing had a solenoid-operated valve (energize to open) with a ((-)) seat diameter for the water tests and a ((-)) manual ball valve for the air tests. The trip valve planned for

- c the ECCS valves is a solenoid-operated valve (energize to close) with a ((-)) seat diameter. no action 109 -

The trip line configuration used in the POC testing provided a smaller elevation difference between the trip valve and IAB valve than will be present in the actual NuScale reactor. In addition, the fluid volume

- d in the trip line configuration for the POC testing was less than will be present in the actual NuScale installed configuration. no action 110 -

The accumulator used for the POC testing had significantly less volume for the main valve pressure than will be present in the NuScale RPV. The pressures applied in the POC testing were not always consistent with the actual pressures for operation of the ECCS valve and its subcomponent valves. The POC testing resulted in accumulator pressure reduction during the tests more significant than would

- e occur during the actual ECCS valve operation. In addition, the POC testing provided the trip line exhaust to atmospheric conditions rather than the CNV conditions. no action 111 -

The NRC staff will evaluate the design testing of the ECCS valves to demonstrate the safety features of the ECCS valves for the actual valve design, configuration, and operating and design-basis

- - conditions. no action 112 -

During the onsite audit, the NRC staff discussed the POC testing with NuScale and Target Rock personnel. The staff indicates the remaining review items related to the POC testing to support the

- status demonstration of the design of the ECCS valves in this audit report. no action 112 -

The report of the POC testing concluded that, overall, the test program was highly successful and proved that the proposed ECCS valve design can operate as designed. However, the test report identified 14 - several key aspects to be addressed during the detailed design and testing such as the following: no action - -

Sizing of the trip valve is critical for the trip valve to adequately vent the trip line to allow operation of the main valve and to allow the IAB valve to immediately seat to prevent premature opening of the main

- a valve. no action 113 -

- b Sizing of the trip line, fittings, and orifice is critical to adequately vent the trip line. no action 114 -

- c In that the proof-of-concept testing included only air and water tests, the effects of hot water, steam, and flashing will need to be assessed. no action 115 -

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1. sub Subject/Item Category Index NRC Notes

- d The effect on valve performance from the differences between test facilities and the RPV will need to be assessed. no action 116 -

The NRC staff will evaluate the design testing of the ECCS valve (including its four valve subcomponents) to address the issues identified during the POC testing and issues identified during the detailed

- - design process and NRC staff audit findings. no action 117 -

During the onsite audit, the NRC staff discussed the POC test with NuScale and Target Rock personnel. The staff indicates the remaining review items related to the POC testing to support the

- status demonstration of the design of the ECCS valves in this audit report. no action 117 -

In its response to RAI 8820, dated August 1, 2017, NuScale specified the schedule for the availability of ECCS valve design documents as follows: design drawings (October 2017), FMEA (December 2017),

qualification plan (December 2017), test plans (May 2018), and initial tests and analyses (December 2019). NuScale was not able to make available the FMEA and qualification plan for the ECCS valves for 15 - review during this audit. The NRC staff will review these documents supporting the design of the ECCS valves during a future audit. no action 118 -

During the onsite audit, the NRC staff discussed the FMEA and Qualification Plan for the ECCS valves with NuScale and Target Rock personnel. The staff indicates the remaining review items related to the

- status FMEA and Qualification Plan to support the demonstration of the design of the ECCS valves in this audit report. no action 118 -

In its response to RAI 8820, NuScale stated that the justification of the IAB valve as a passive mechanical component is provided in the response to RAI 15-2. The NRC staff reviewed the NuScale response to RAI 15-2 (dated July 21, 2017) and determined that the information is not sufficient to justify the IAB valve as a passive device consistent with the Commission policy. For example, Commission Paper SECY-77-439 (dated August 17, 1977), Single Failure Criterion, specified that simple check valves could be considered passive components in the then-current operating plant designs. Commission Paper SECY-94-084 indicated that check valves in new reactors with passive cooling systems might not be justified as passive components, because the driving head to open check valves in passive cooling systems might rely on gravity rather than pump flow. SECY-94-084 specified that a failure probability on the order of 1E-4 per year or less would be low enough to be considered a passive failure.

Commission Paper SECY-05-138 (dated August 2, 2005), Risk-Informed and Performance-Based Alternatives to the Single-Failure Criterion, described the NRC consideration of passive components in 16 - nuclear power plants. The NRC staff will review the design tests and analyses to justify the IAB valve as a passive component consistent with Commission policy during a future audit. no action 119 -

During the onsite audit, the NRC staff discussed the NuScale assumption of the IAB valve as passive component with respect to the single failure criterion with NuScale and Target Rock personnel. The

- status staff indicates the remaining review items related to the passive component assumption for the IAB valves to support the demonstration of the design of the ECCS valves in this audit report. no action 119 -

In its response to RAI 8820, NuScale stated that the ECCS valves will be designed in accordance with the ASME BPV Code, including capacity certification, with ASME design reports developed in accordance with COL items. The NRC staff conducted a Phase 1 audit of the ECCS valve design specifications and provided comments to NuScale. NuScale stated that the Phase 1 audit comments have been addressed in the ECCS valve specifications and will be available for review in early 2018. The NRC staff will conduct a follow-up audit of the design specifications to verify that the comments have 17 - been addressed to support the design of the ECCS valves. no action 120 -

- status The NRC staff is conducting a follow-up audit of the NuScale design specifications, including the ECCS valve design specification. no action 120 -

18 - In its response to RAI 8820, NuScale summarized the proposed FSAR Tier 1 inspections, tests, analyses, and acceptance criteria (ITAAC) for the ECCS valves. no action 121 -

- status The NRC staff is reviewing the ITAAC for the ECCS valves through a separate RAI process. no action 121 -

TECH ISSUES INDEX #s RESOLUTION TECH ISSUE - POC TESTING 1, 3, 5, 6, 7, 8, 32 DCA Demonstration Testing TECH ISSUE - PARTIAL OPEN 9, 10, 11, 12, 13, Formalize force balance & tilt 35, 52, 95 calculations TECH ISSUE - IAB PASSIVE 4, 14, 15, 16, 17 This issue is being addressed seperately from this audit TECH ISSUE - VALVE SYSTEM OPERATION AT OPERATING CONDITIONS 2, 33, 34, 36 DCA Demonstration Testing TECH ISSUE - NON-VALVE FAILURE MODES EVAL (power/tubing) 28, 39, 64 Provide written response TECH ISSUE - DIFFUSER REVERSE FLOW 37 Provide written response TECH ISSUE - MAIN VALVE SPRING CREDIT FOR SAFETY 43 Provide written response TECH ISSUE - ADDRESS DAVIS BESSE LESSONS LEARNED 46 Provide written response TECH ISSUE - VALVE INTERNAL FILTER PERFORMANCE 47, 53, 57 Provide written response NuScale Nonproprietary