ML18355A905
| ML18355A905 | |
| Person / Time | |
|---|---|
| Site: | NuScale |
| Issue date: | 12/21/2018 |
| From: | Rad Z NuScale |
| To: | Document Control Desk, Office of New Reactors |
| References | |
| RAIO-1218-63954 | |
| Download: ML18355A905 (13) | |
Text
RAIO-1218-63954 December 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 Supplemental Response to NRC Request for Additional Information No. 196 (eRAI No. 9050) on the NuScale Design Certification Application
REFERENCES:
- 1. U.S. Nuclear Regulatory Commission, "Request for Additional Information No. 196 (eRAI No. 9050)," dated August 25, 2017
- 2. NuScale Power, LLC Response to NRC "Request for Additional Information No. 196 (eRAI No.9050)," dated October 17, 2017 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) supplemental response to the referenced NRC Request for Additional Information (RAI).
The Enclosure to this letter contains NuScale's supplemental response to the following RAI Question from NRC eRAI No. 9050:
16-17 This letter and the enclosed response make no new regulatory commitments and no revisions to any existing regulatory commitments.
If you have any questions on this response, please contact Carrie Fosaaen at 541-452-7126 or at cfosaaen@nuscalepower.com.
Sincerely, Zackary W. Rad Director, Regulatory Affairs NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A Getachew Tesfaye, NRC, OWFN-8H12 : NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9050 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9050 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com
Response to Request for Additional Information Docket No.52-048 eRAI No.: 9050 Date of RAI Issue: 08/25/2017 NRC Question No.: 16-17 Paragraph (a)(11) of 10 CFR 52.47 and paragraph (a)(30) of 10 CFR 52.79 state that a design certification (DC) applicant and a combined license (COL) applicant, respectively, are to propose technical specifications (TS) prepared in accordance with 10 CFR 50.36 and 50.36a.
10 CFR 50.36 sets forth requirements for TS to be included as part of the operating license for a nuclear power facility. The model standard technical specifications (STS) in the following documents provide NRC guidance on format and content of TS as acceptable means to meet 10 CFR 50.36 requirements. These documents may be accessed using the Agencywide Documents Access and Management Systems (ADAMS) by their accession numbers.
NUREG-1431, STS Westinghouse Plants, Revision 4 (ADAMS Accession Nos.
ML12100A222 and ML12100A228)
NUREG-1432, STS Combustion Engineering Plants, Revision 4 (ADAMS Accession Nos. ML12102A165 and ML12102A169)
NUREG-2194, STS Westinghouse Advanced Passive 1000 (AP1000) Plants, Revision 0 (ADAMS Accession No. ML16111A132)
The NRC staff needs to evaluate technical differences in the proposed generic TS (GTS) from applicable provisions in these documents, which are referenced by the DC applicant in Design Control Document (DCD) Tier 2, Section 16.1, and the docketed rationale for each difference because conformance to STS provisions is used in the safety review as the initial point of guidance for evaluating the adequacy of the GTS to ensure adequate protection of public health and safety, and the completeness and accuracy of the GTS Bases.
NuScale Nonproprietary
In the Applicable Safety Analyses, LCO, and Applicability (ASA-LCO-A) section of Bases Subsection B 3.3.1, below the heading Design Basis Definition
- a. The 1st paragraph states:
The MPS is designed to ensure that the following operational criteria are met:
The associated actuation will occur when the parameter monitored by each channel reaches its setpoint and the specific coincidence logic is satisfied; and Separation and redundancy are maintained to permit a channel to be out of service for testing or maintenance while still maintaining redundancy within the MPS instrumentation architecture.
The applicant is requested to justify using parameter instead of variable or process variable in the first bullet.
Note that this is an example of a global (DCA-wide) request to check for consistency in the use of the terms parameters and variables.
- b. The 2nd paragraph states:
All design basis events can be mitigated by one or more MPS Functions. The accident analysis takes credit for most of the MPS trip Functions.
The applicant is requested to list the uncredited MPS trip Functions and discuss why each of these MPS trip Functions is not credited in each of the relevant accident analyses, with a reference to the DCD subsections that describe each analysis.
For any DCD accident analysis description that does not explicitly state the applicable uncredited MPS trip Functions, consider revising the analysis description to list the applicable uncredited Functions with an explanation of why each applicable Function is not credited for that analysis.
NuScale Nonproprietary
Also consider whether to include in the Bases for each MPS trip Function a list of the relevant accidents that do not credit the Function and the associated rationale.
NuScale Response:
This response addresses staff questions regarding the calibration of the undervoltage (UV) and overcurrent (OC) isolation functions of the Class 1E isolation devices. The staff also asked that the bases be modified to indicated that the setpoints will be controlled in accordance with the Setpoint Program required by TS 5.5.10. The issue was identified by the staff during a public meeting on November 6, 2018.
The design of the Class 1E isolation devices has not been finalized. The devices will include OC and UV protective functions that isolate the Module Protection System (MPS) from its non-Class 1E power source. Isolation of postulated degraded electrical power to the MPS is considered a necessary attendant function for MPS OPERABILITY. The design of the MPS causes the affected components to actuate to their safety position if interruption of electrical power occurs.
SR 3.3.1.5 required the OPERABILITY of Class 1E isolation devices to be verified in accordance with the Surveillance Frequency Control Program (SFCP). To clarify the required testing and address the identified concern, SR 3.3.1.5, SR 3.3.2.3, and SR 3.3.3.3 have been changed to require CHANNEL CALIBRATION of the Class 1E isolation devices. The definition of CHANNEL CALIBRATION will ensure appropriate testing of the Class 1E isolation devices including their setpoints. The Bases of SR 3.3.1.5, SR 3.3.2.3, and SR 3.3.3.3 have been modified to describe the Class 1E isolation devices to include the OC and UV function as a required part of their function and OPERABILITY. The revised bases also indicate that the OC and UV setpoints are considered variable having significant safety functions and are therefore within the scope of applicability of the Setpoint Program as described in specification 5.5.10.a.
The Note at SR 3.3.2.3 and SR 3.3.3.3 has been added to SR 3.3.1.5 and associated bases stating that the SR is not required to be met for Class 1E isolation devices that have isolated 1E circuits from non-1E power. This allowance is appropriate because with the 1E circuits isolated from the non-1E power, the safety function of the device has been performed.
The basis for the surveillance interval for SR 3.3.1.5 is provided in FSAR Table 16.1-1 as [t]he 24 month Frequency is acceptable based on consideration of the design reliability of the equipment. The basis for the surveillance interval for SR 3.3.2.3 and SR 3.3.3.3 in FSAR Table 16.1-1 is The 24 month Frequency is based on the potential for unplanned plant transients if NuScale Nonproprietary
the Surveillances were performed with the unit at power. The 24 month Frequency is also acceptable based on consideration of the design reliability of the equipment. The latter basis describes a potential for unplanned plant transients that could occur with the unit at power, however SR 3.3.1.5 does not include this basis. The difference in justification is that SR 3.3.1.5 applies to portions of MPS with additional redundancy such that the likelihood of unplanned plant transients has reduced so that is considered negligible.
Impact on DCA:
The Technical Specifications have been been revised as described in the response above and as shown in the markup provided in this response.
NuScale Nonproprietary
MPS Instrumentation 3.3.1 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.3.1.4 -------------------------------NOTE-----------------------------
Neutron detectors are excluded from the CHANNEL CALIBRATION.
Perform CHANNEL CALIBRATION on each In accordance with required channel listed in Table 3.3.1-1. the Surveillance Frequency Control Program SR 3.3.1.5 -------------------------------NOTE----------------------------- In accordance with Not required to be met for Class 1E isolation the Surveillance devices that have isolated 1E circuits from non-1E Frequency Control power. Program.
Perform CHANNEL CALIBRATION on each required Class 1E isolation device.Verify associated Class 1E isolation devices are OPERABLE.
NuScale 3.3.1-6 Draft Revision 3.0
Reactor Trip System Logic and Actuation 3.3.2 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.3.2.1 ------------------------------NOTE------------------------------
Not required to be met for reactor trip breakers that are open.
Perform ACTUATION LOGIC TEST. In accordance with the Surveillance Frequency Control Program SR 3.3.2.2 ------------------------------NOTE------------------------------
Not required to be met for reactor trip breakers that are open.
Verify required response time is within limits.
In accordance with the Surveillance Frequency Control Program SR 3.3.2.3 ------------------------------NOTE------------------------------
Not required to be met for Class 1E isolation devices that have isolated 1E circuits from non-1E power.
Perform CHANNEL CALIBRATION on each required In accordance with Class 1E isolation device.Verify associated Class 1E the Surveillance isolation devices are OPERABLE. Frequency Control Program SR 3.3.2.4 ------------------------------NOTE------------------------------
Not required to be met for reactor trip breakers that are open.
Verify each RTB actuates to the open position on an In accordance with actual or simulated actuation signal. the Surveillance Frequency Control Program NuScale 3.3.2-2 Draft Revision 3.0
ESFAS Logic and Actuation 3.3.3 SURVEILLANCE REQUIREMENTS (continued)
SR 3.3.3.3 -------------------------------NOTE--------------------------------
Not required to be met for Class 1E isolation devices that have isolated 1E circuits from non-1E power.
Perform CHANNEL CALIBRATION on each required In accordance with Class 1E isolation deviceVerify associated Class 1E the Surveillance isolation devices are OPERABLE. Frequency Control Program SR 3.3.3.4 -------------------------------NOTE--------------------------------
Not required to be met for pressurizer heater trip breakers that are open or breakers closed under administrative controls.
Verify each pressurizer heater trip breaker (PHTB) In accordance with actuates to the open position on an actual or the Surveillance simulated actuation signal. Frequency Control Program NuScale 3.3.3-5 Draft Revision 3.0
Module Protection System Instrumentation B 3.3.1 BASES SURVEILLANCE REQUIREMENTS (continued)
When an interlock or permissive is not supporting the associated Function's OPERABILITY at the existing plant conditions, the affected Function's channels must be declared inoperable and appropriate ACTIONS taken.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
SR 3.3.1.5 SR 3.3.1.5 is the performance of a CHANNEL CALIBRATION of the Class 1E isolation devices, as described in SR 3.3.1.4.
A note provides an allowance for the SR so that it does not need to be met for class 1E isolation devices that have isolated the 1E circuits from the non-1E power. This allowance permits continued operation when an isolation device that may not be able to satisfy the requirements of the SR but that has already performed its safety function.
Class 1E isolation devices ensure that electrical power to the associated MPS circuitry and logic will not adversely affect the ability of the system to perform its safety functions. The devices de-energize and isolate the MPS components if such a condition is detected. This surveillance verifies the setpoints and functions of the isolation devices including associated alarms and indications by performing a CHANNEL CALIBRATION of required Class 1E isolation devices. The overcurrent and undervoltage setpoints of the Class 1E isolation devices are established and controlled in accordance with the Setpoint Program.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
NuScale B 3.3.1-52 Draft Revision 3.0
RTS Logic and Actuation B 3.3.2 BASES SURVEILLANCE REQUIREMENTS (continued)
SR 3.3.2.2 This SR ensures that the response time of the RTS divisions are verified to be less than or equal to the maximum values assumed in the safety analysis. Individual component response times are not modeled in the analyses. The analyses model the overall or total elapsed time, from the point at which the process variable exceeds the trip setpoint value at the sensor to the time at which the RTBs open. Total response time may be verified by any series of sequential, overlapping, or total channel measurements.
Response times of the sensors are tested in accordance with LCO 3.3.1.
The maximum digital time response is described in the FSAR. This SR encompasses the response time of the RTS division from the output of the equipment interface modules until the RTBs are open.
A note provides an allowance for the SR so that it does not need to be met for reactor trip breakers that are open. This allowance permits continued operation when a trip breaker may not be able to satisfy the requirements of the SR but is already open. When a reactor trip breaker is open it has performed its safety function.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
SR 3.3.2.3 SR 3.3.2.3 is the performance of a CHANNEL CALIBRATION of the Class 1E isolation devices, as described in SR 3.3.1.4.
A note provides an allowance for the SR so that it does not need to be met for class 1E isolation devices that have isolated the 1E circuits from the non-1E power. This allowance permits continued operation when an isolation device that may not be able to satisfy the requirements of the SR but that has already performed its safety function.
Class 1E isolation devices ensure that electrical power to the associated MPS circuitry and logic will not adversely affect the ability of the system to perform its safety function. The devices de-energize and isolate the MPS components if such a condition is detected. This surveillance verifies the setpoints and functions of the isolation devices including associated alarms and indications by performing a CHANNEL CALIBRATION of required Class 1E isolation devices.
NuScale B 3.3.2-5 Draft Revision 3.0
RTS Logic and Actuation B 3.3.2 BASES SURVEILLANCE REQUIREMENTS (continued)
The overcurrent and undervoltage setpoints of the Class 1E isolation devices are established and controlled in accordance with the Setpoint Program.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
NuScale B 3.3.2-6 Draft Revision 3.0
ESFAS Logic and Actuation B 3.3.3 BASES SURVEILLANCE REQUIREMENTS (continued)
SR 3.3.3.3 SR 3.3.3.3 is the performance of a CHANNEL CALIBRATION of the Class 1E isolation devices, as described in SR 3.3.1.4.
A note provides an allowance for the SR so that it does not need to be met for class 1E isolation devices that have isolated the 1E circuits from the non-1E power. This allowance permits continued operation when an isolation device that may not be able to satisfy the requirements of the SR but that has already performed its safety function.
Class 1E isolation devices ensure that electrical power to the associated MPS circuitry and logic will not adversely affect the ability of the system to perform its safety functions. The devices de-energize and isolate the MPS components if such a condition is detected. This surveillance verifies the setpoints and functions of the isolation devices including associated alarms and indications by performing a CHANNEL CALIBRATION of required Class 1E isolation devices. The overcurrent and undervoltage setpoints of the Class 1E isolation devices are established and controlled in accordance with the Setpoint Program.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
SR 3.3.3.4 SR 3.3.3.4 verifies the pressurizer heater trip breaker (PHTB) actuates to the open position on an actual or simulated trip signal on each PHTB.
This test verifies OPERABILITY by actuation of the end devices. The PHTB test verifies the under voltage trip mechanism opens the breaker. A Note is provided indicating that the SR does not need to be met for pressurizer heater trip breakers that are open or closed under administrative control. This allowance permits continued operation when a trip breaker may not be able to satisfy the requirements of the SR but is already open or can be quickly opened by administrative means. When a pressurizer heater trip breaker is open it has performed its safety function.
This is acceptable because of the slowly occurring nature of the phenomena the automatic heater trip breakers mitigate.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
NuScale B 3.3.3-11 Draft Revision 3.0