ML24326A094

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Response to NuScale Technical Report Audit Question Number: A-16-9
ML24326A094
Person / Time
Site: 05200050
Issue date: 11/21/2024
From:
NuScale
To:
Office of Nuclear Reactor Regulation
Shared Package
ML24326A092 List:
References
LO-175900
Download: ML24326A094 (1)


Text

Response to NuScale Technical Report Audit Question Question Number: A-16-9 Receipt Date: 09/18/2023 Question:

TR101310-NP, Rev 0, Section 3.1.1 describes departures from the US600 generic TS Section 1.1 definitions in the US460 generic TS Section 1.1 definitions. The description under the heading PASSIVELY COOLED - PASSIVE COOLING seems to suggest that the US460 NuScale Power Module (NPM or just module) design needs more than one RVV and more than one RRV to perform the ECCS safety function for some unstated design basis events.

Suggest changing the sentence ECCSonly requires one or more RVVs and one or more RRVs to be open to perform its safety function to say ECCSonly requires one of the two RVVs and one of the two RRVs to be open to perform its safety function.

Response

Original Response:

NuScale revises the definition of PASSIVELY COOLED - PASSIVE COOLING in TR-101310 Section 3.1.1 to read:

...only requires one of the two RVVs and one of the two RRVs to be open...

NuScale revises the definition of PASSIVELY COOLED - PASSIVE COOLING in SDAA Technical Specification 1.1 to read:

a. One of the two reactor vent valves are open and one of the two reactor recirculation valves are open, or
b. One of the two trains of DHRS is in operation,or NuScale Nonproprietary NuScale Nonproprietary

Revised Response:

Subsequent to the posting of the original response to Audit Item A-16-9, NuScale identified concerns with the revised definition of Passively Cooled - Passive Cooling in Generic Technical Specification Section 1.1. The revised wording could lead to an incorrect application of the definition. This concern was discussed with the NRC staff on October 24, 2024 and it was agreed that the definition of Passively Cooled - Passive Cooling should be revised to return the definition to the original wording.

Audit Item A-16.1.1-4 requested that NuScale revise method b. of the definition of Passively Cooled - Passive Cooling to replace is with are. Because the definition had been previously revised to use One of the two in both method a, and b., NuScale responded that it was more appropriate to use is in method a. and b. Now that the wording of methods a. and b.are being returned to the original wording, methods a. and b. are revised to use are instead of is. This change aligns with the action requested by Audit Item A-16.1.1-4.

NuScale revises the definition of PASSIVELY COOLED - PASSIVE COOLING in Generic Technical Specification 1.1 to read:

a. One or more reactor vent valves are open and one or more reactor recirculation valves are open, or
b. One or more trains of DHRS are in operation,or Markups of the affected changes, as described in the response, are provided below:

NuScale Nonproprietary NuScale Nonproprietary

Definitions 1.1 NuScale US460 1.1-5 Draft Revision 2 1.1 Definitions PASSIVELY COOLED -

PASSIVE COOLING A module is in PASSIVE COOLING or is being PASSIVELY COOLED when:

a. One or more reactor vent valves are open and one or more reactor recirculation valves are open, or
b. One or more trains of DHRS areis in operation, or
c. Water level in the containment vessel is > 45 ft.

PHYSICS TESTS PHYSICS TESTS shall be those tests performed to measure the fundamental nuclear characteristics of the reactor core and related instrumentation. These tests are:

a. Described in Chapter 14, Initial Test Program and Inspections, Tests, Analyses, and Acceptance Criteria, of the FSAR;
b. Authorized under the provisions of 10 CFR 50.59; or
c. Otherwise approved by the Nuclear Regulatory Commission.

PRESSURE AND TEMPERATURE LIMITS REPORT (PTLR)

The PTLR is the unit-specific document that provides the reactor vessel pressure and temperature limits, including heatup and cooldown rates, for the current reactor vessel fluence period. These pressure and temperature limits shall be determined for each fluence period in accordance with Specification 5.6.4.

RATED THERMAL POWER (RTP)

RTP shall be a total reactor core heat transfer rate to the reactor coolant of 250 MWt.