ML19212A762

LLC Response to NRC Request for Additional Information No. 523 (Erai No. 9682) on the NuScale Design Certification Application

ML19212A762
Person / Time
Site:	NuScale
Issue date:	07/31/2019
From:	Rad Z NuScale
To:	Document Control Desk, Office of New Reactors
References
RAIO-0719-66506
Download: ML19212A762 (9)

Text

RAIO-0719-66506 July 31, 2019 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738

SUBJECT:

NuScale Power, LLC Response to NRC Request for Additional Information No.

523 (eRAI No. 9682) on the NuScale Design Certification Application

REFERENCES:

1. U.S. Nuclear Regulatory Commission, "Request for Additional Information No. 523 (eRAI No. 9682)," dated June 06, 2019

2. NuScale Power, LLC Response to NRC "Request for Additional Information No. 523 (eRAI No.9682)," dated July 26, 2019 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) response to the referenced NRC Request for Additional Information (RAI).

The Enclosure to this letter contains NuScale's response to the following RAI Question from NRC eRAI No. 9682:

12.03-67 The responses to RAI Questions 12.03-64 and 12.03-65 were previously provided in Reference

2. The response to question 12.3-66 will be provided by August 26, 2019.

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-8H12 Samuel Lee, NRC, OWFN-8H12 Getachew Tesfaye, NRC, OWFN-8H12 : NuScale Response to NRC Request for Additional Information eRAI No. 9682 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

RAIO-0719-66506 :

NuScale Response to NRC Request for Additional Information eRAI No. 9682 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.: 9682 Date of RAI Issue: 06/06/2019 NRC Question No.: 12.03-67 Regulatory Basis:

10 CFR 50.34(f)(2)(vii) requires that applicants perform radiation and shielding design reviews of spaces around systems that may, as a result of an accident, contain accident source term radioactive materials, and design as necessary to permit adequate access to important areas.

10 CFR Part 20 establishes standards for protection against ionizing radiation resulting from activities conducted under licenses issued by the Nuclear Regulatory Commission. In addition, 10 CFR Part 20, Subpart C, establishes the occupational dose limits.

In addition, while NUREG-0737 doesn't establish regulatory requirements for the NuScale application, NUREG-0737,Section II.B.2, provides context regarding the actions that should be considered in addressing the requirement of 10 CFR 50.34(f)(2)(vii). NUREG-0737,Section II.B.2, indicates that any area which will or may require occupancy to permit an operator to aid in the mitigation of or recovery from an accident are areas that should be reviewed to ensure that adequate access is permitted. Furthermore,Section II.B.2 provides numerous examples of areas that should be considered for this evaluation, these areas include to the hydrogen control system and containment isolation reset control area. These examples clearly specify that actions associated with hydrogen control and isolation of containment should be considered as actions necessary for consideration to meeting 10 CFR 50.34(f)(2)(vii). Furthermore,Section II.B.2 indicates that the dose criteria used for this evaluation should be 5 rem.

Background:

On January 31, 2019, NuScale submitted an exemption request from 10 CFR 50.34(f)(2)(viii).

NuScale indicates in the exemption request that part of the basis for the exemption is because the NuScale design includes the capability to perform hydrogen and oxygen monitoring in NuScale Nonproprietary

accordance with 10 CFR 50.44(c)(4). NuScale describes the process for conducting hydrogen and oxygen monitoring in the FSAR and in TR-0716-50424, "Combustible Gas Control," which requires un-isolating containment. While NuScale has indicated that they do not believe they have any required actions within the scope of 10 CFR 50.34(f)(2)(vii), NuScale is required to perform hydrogen and oxygen monitoring under 10 CFR 50.44(c)(4) and NuScale has not provided justification regarding if there is a need to re-isolate containment. In addition, staff requests additional information related to the exemption request.

Issue:

NuScale has not provided information regarding if manual actions associated with re-isolating containment are necessary. In addition, the staff requests additional information regarding information related to the exemption request.

Requests:

1. After opening containment to perform hydrogen and oxygen monitoring, discuss if there is a need to re-isolate containment. If manual actions may be necessary to re-isolate containment, please describe these manual actions. If re-isolation of containment is unnecessary, please explain why.

2. If manual actions are necessary to re-isolate containment, please demonstrate adequate safe access to perform the necessary actions to isolate containment (similar to the radiological review performed to ensure the capability to perform hydrogen and oxygen monitoring actions) to demonstrate compliance with 10 CFR 50.34(f)(2)(vii) or justify why the access requirements of 10 CFR 50.34(f)(2)(vii) would not apply to manual actions to re-isolate containment.

3. On March 29, 2019, NuScale provided proposed FSAR markups associated with the exemption request from 10 CFR 50.34(f)(2)(viii). In the proposed FSAR changes associated with the exemption request, the applicant proposed to remove the post-accident radiation zone maps provided in FSAR Figures 12.3-4a through 12.3-4d but did not provide any information or justification explaining why they are being removed. The post-accident radiation zone figures provide information relevant to ensuring post-accident doses to operators are appropriate.

Please also provide all post-accident radiation zone information necessary to provide information demonstrating that post-accident actions can be performed within the dose limits in the NuScale FSAR.

4. The staff determined that FSAR Figures 9.3.6-1, "Containment Evacuation System Diagram" and 9.3.6-2, "Containment Flooding and Drain System Diagram," contain NuScale Nonproprietary

inconsistencies and lack sufficient detail to evaluate necessary actions in post-accident conditions. Please ensure that the FSAR Figures 9.3.6-1 and 9.3.6-2 provide consistent, accurate, and up to date information and the appropriate level of detail for the staff to make a finding relative to the acceptability of these systems for performing required functions.

5. The staff cannot locate a diagram depicting the configuration of the sampling system in the FSAR. However, during public meetings, the applicant indicated that this system contained the pump used for pumping post-accident fluid, along with valves and piping not shown on the connected systems. Please update the FSAR to provide a figure showing the configuration of the sampling system with the appropriate level of detail for the staff to make a finding relative to the acceptability of these systems for performing required functions. As an alternative, ensure that the FSAR provides an adequate description of the configuration of the system or justify why it is not necessary.

NuScale Response:

1. The NuScale design includes equipment that provides the capability for monitoring hydrogen and oxygen in containment. This equipment is functional, reliable and capable of continuously measuring the concentration of hydrogen and oxygen in the containment atmosphere following a significant beyond design basis accident. NuScale analyses have shown that there is no credible threat to containment integrity due to combustible gases for the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> post-event. There is no anticipated need for re-isolating containment after opening containment to perform hydrogen and oxygen monitoring, however the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> time frame allows for the development of necessary action plans appropriate for the situation. Because this event is categorized as a significant beyond design basis event, the actions taken by plant personnel will be guided and managed by the emergency response organization, consistent with 10 CFR 50.47(b).

Because this hydrogen and oxygen monitoring equipment is provided for the purposes of severe accident monitoring and is not credited in any design basis accident, operator radiological consequences need not be evaluated. This is analogous to the approach in Regulatory Guide 1.183 pertaining to offsite radiological consequences of containment purging operations, which states that radiological consequences of containment purging operations need not be evaluated if the installed containment purging capabilities are maintained for purposes of severe accident management and are not credited in any design basis analysis.

NuScale Nonproprietary

2. As stated above, there is no anticipated need for re-isolating containment after opening containment to perform hydrogen and oxygen monitoring, however any actions taken by plant personnel will be guided and managed by the emergency response organization, consistent with 10 CFR 50.47(b). As described in Section 9.3, this system is used during normal operations, so any leaks would be identified during normal operations and remedied. Therefore, it would be reasonable to assume that the system's integrity is intact.

3. FSAR Figures 12.3-4a through 12.3-4d were removed from the FSAR as part of the conforming changes associated with the 10 CFR 50.34(f)(2)(viii) exemption request. Because there are no credited post-accident operator actions outside the main control room for design basis accidents, there is no need for radiation zone map information involving post-accident doses to operators.

4. FSAR Figure 9.3.6-1 and Figure 9.3.6-2 have been revised to depict the CES and CFDS valves used during hydrogen monitoring.

5. FSAR Figure 9.3.2-1 has been added depicting the configuration of the containment sampling system which is part of the process sampling system.

Impact on DCA:

FSAR Figure 9.3.2-1 has been added and Figure 9.3.6-1 and Figure 9.3.6-2 have been revised as described in the response above and as shown in the markup provided in this response.

NuScale Nonproprietary

NuScale Final Safety Analysis Report Process Auxiliaries RAI 09.03.02-3, RAI 09.03.02-4, RAI 09.03.02-5, RAI 09.03.02-6, RAI 09.03.02-8 Figure 9.3.6-2: Containment Flooding and Drain System Diagram FROM RPCS S FROM PSS MODULE 02 S

FROM PSS E

MODULE 03 H E

S H FROM PSS CNV MODULE 04 S

FROM PSS RPV MODULE 05 S

FROM PSS MODULE 06 CONTAINMENT FLOODING S AND DRAIN PUMPS FROM PSS FROM REACTOR POOL FILTER RE BANK TO RBVS DRAIN SEPARATOR TO RPCS MODULE 01 Tier 2 9.3-108 Draft Revision 3

NuScale Final Safety Analysis Report Process Auxiliaries RAI 05.02.05-1 Figure 9.3.6-1: Containment Evacuation System Diagram RE CES RBVS TO RBVS M

SAS CES FILTER BANK FROM SAS CES GRWS SAS CES TO GRWS FROM SAS SAS CES CES PSS CONDENSER S FROM SAS FROM PSS VACUUM PUMPS PIT CES PSS S

PIT TO PSS CES PIPE GALLERY WALL CNTS E

H RE E

H SAMPLE LIT VESSEL CNV CES RWDS RPV TO RWDS Tier 2 9.3-107 Draft Revision 3

NuScale Final Safety Analysis Report Process Auxiliaries RAI 12.03-67 Figure 9.3.2-1: Containment Sampling System Diagram PSS CONTAINMENT SAMPLING SYSTEM SKID S

FROM CES (ET) (ET) (ET) (ET) (ET) TO CES (ET)

(ET)

(ET)

(ET)

(ET) (ET)

(ET)

(ET)

AIT AE (ET)

H2 AE O2 (ET)

(ET)

(ET) (ET)

(ET)

(ET)

SAMPLE (ET)

PUMP (ET) P (ET) (ET) (ET) (ET) (ET) TO CFDS S

Tier 2 9.3-48 Draft Revision 3