ML15041A062
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| ML15041A062 | |
| Person / Time | |
|---|---|
| Site: | Technical Specifications Task Force |
| Issue date: | 02/01/2015 |
| From: | Technical Specifications Task Force |
| To: | Division of Policy and Rulemaking |
| Honcharik M C | |
| Shared Package | |
| ML15040A069 | List: |
| References | |
| Download: ML15041A062 (8) | |
Text
- NUREG-0800, The Standard Review Plan for the Review of Safety Analysis Reports [SAR] for Nuclear Power Plants: LWR [Light Water Reactor] Edition - Transient and Accident Analysis (SRP Chapter 15) Section 15.4.6, "Inadvertent Decrease In Boron Concentration in the Reactor Coolant System (PWR)," (ADAMS Accession No. ML070380222) Item 4 on page 15.4.6-8, states: When necessary, the reviewer evaluates the effects of single active failures of systems and components that may affect the course of the transient. This phase of the review uses SRP system review procedures for SAR Chapters 5, 6, 7, 8, and 9. In particular, redundant alarms that alert the operator to the unplanned dilution are confirmed. It is the NRC staff's understanding that the operator relies upon a neutron flux alarm to identify and terminate a design basis boron dilution event or to detect a misloaded assembly. Additionally, licensees use the neutron flux alarm to alert personnel working in the vicinity of the reactor of the high neutron flux condition (via local alarm and/or announcement) and to prevent possible offsite releases of radioactive material. *
- During core alterations (i.e., movement of fuel), there is the potential for operable neutron detectors to become effectively decoupled from the fuel assemblies being monitored. For example, some plants have only two source range monitors (one for each half of the core). If one source range monitor becomes inoperable, and certain, strategically located fuel assemblies are removed; then the other, operable neutron source monitor may no longer be capable of monitoring some fuel assemblies that are located in the far half of the core. Therefore, the NRC staff is concerned that the removal of the words CORE ALTERATIONS from the TS LCO for source range monitors may create a situation where a boron dilution accident, misloaded fuel assembly, or an increase in neutron flux might go undetected. The NRC staff's preliminary review of this issue indicates that the removal of the words CORE ALTERATIONS may create a situation not consistent with the SRP guidance related to "redundant alarms," described in SRP Section 15.4.6. The NRC staff is concerned that a dropped source, fuel assembly, or component (or any other item allowed to be moved by CORE ALTERATIONS) could damage a fuel assembly or break creating a radioactive source term. Additionally, a dropped source, component, or fuel assembly could add reactivity if it is dropped over or in the vicinity of other fuel. If so, the NRC staff may require an analysis to show that the dose consequences of these scenarios are less limiting than the current fuel handling accident. The NRC staff is also concerned that if there is no definition of core alterations in the TS there may be some confusion as to the circumstances or operations under which the requirement of Title 10 of the Code of Federal Regulations Section (10 CFR) 50.54 applies. The regulation at 10 CFR 50.54 specifies the assignment of a senior operator dedicated to fuel handling tasks during core alterations. during alteration of the core of a nuclear power unit (including fuel loading or transfer)
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