ML20220A489
| ML20220A489 | |
| Person / Time | |
|---|---|
| Issue date: | 08/05/2020 |
| From: | Michael Snodderly Advisory Committee on Reactor Safeguards |
| To: | Dimitrijevic V, Walter Kirchner Advisory Committee on Reactor Safeguards |
| Snodderly M | |
| References | |
| Download: ML20220A489 (2) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, DC 20555 - 0001 August 5, 2020 MEMORANDUM TO:
Walter L. Kirchner, Chairman Vesna B. Dimitrijevic, Member NuScale Subcommittee Advisory Committee on Reactor Safeguards FROM:
Mike Snodderly, Senior Staff Engineer /RA/
Technical Support Branch Advisory Committee on Reactor Safeguards
SUBJECT:
ANALYSIS OF NRR RESPONSE TO ACRS LETTER ON NUSCALE COMBUSTIBLE GAS MONITORING Attached is a copy of the May 18, 2020, Office of Nuclear Reactor Regulation (NRR) response to the April 28, 2020, ACRS letter on NuScale Combustible Gas Monitoring. A copy of the Committees letter is also attached.
Committee Letter:
In its April 28, 2020 letter:
The Committee concurred with the staff position that the combustible gas monitoring system design not receive finality in the NuScale design certification because the staff is unable to evaluate dose implications.
The Committee was concerned that to obtain a sample representative of the containment atmosphere, the proposed combustible gas monitoring system design will require establishing a sizeable flow through non-safety-grade piping outside containment. This may have implications on worker and off-site doses.
CONTACT: Mike Snodderly, ACRS/TSB 301-415-2241
W. Kirchner and The Committee expects to have the opportunity to review the final design updates submitted by combined license applicants to ensure that our concerns have been addressed and are supported by analyses.
NRR Response:
The NRR Office Director restated the above three conclusions. The NRR Office Director went on to say that they understand the concerns regarding the dose implications for obtaining a representative sample of the containment atmosphere.
The NRR Office Director went on to say that the staff further appreciates the Committees independent concurrence with the staffs position that the combustible gas monitoring system design not receive finality in the NuScale design certification because of a lack of sufficient design information needed to evaluate possible dose impacts. The staff expects more detailed design information will be provided as part of future applications that will reference the NuScale small modular reactor design. Once that additional information is available, the staff plans to conduct a risk-informed review that considers the likelihood of the event sequences which would necessitate initiating this system, the dose consequences of its operation, and the risks for potentially forming a combustible gas mixture. The staff looks forward to working with the Committee on the review of that future application.
Analysis:
I recommend that the Committee accept the staffs response in light of the Committees July 29, 2020 letter report, Report on the Safety Aspects of the NuScale Small Modular Reactor. In this letter report, the Committee stated that a design certification and standard design approval for the NuScale applications should be issued, subject to the staffs proposed exclusions regarding the finality of design requirements: shield wall design, containment leakage from combustible gas monitoring, and steam generator tube structural and leakage integrity.
In addition, the staff acknowledged its expectation that more detailed design information will be provided as part of any future application that will reference the NuScale small modular reactor design.