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Instrument accuracy in reactor vessel inventory tracking systems

01 Jan 1986-
TL;DR: The NRC Regulatory Guide 1.97, which covers accident monitoring instrumentation, was revised (Rev. 3) to be consistent with the requirements of item II.2 of NUREG-0737.
Abstract: Instrumentation needs for detection of inadequate core cooling. Studies of the Three Mile Island accident identified the need for additional instrumentation to detect inadequate core cooling (ICC) in nuclear power plants. Industry studies by plant owners and reactor vendors supported the conclusion that improvements were needed to help operators diagnose the approach to or existence of ICC as well as to provide more complete information for operator control of safety injection flow to minimize the consequences of such an accident. In 1980, the US Nuclear Regulatory Commission (NRC) required further studies by the industry and described ICC instrumentation design requirements that included human factors and environmental considerations. On December 10, 1982, NRC issued to Babcock and Wilcox (B and W) licensees orders for Modification of License and transmitted to pressurized water reactor licensees Generic Letter 82-28 to inform them of the revised NRC requirements. The instrumentation requirements include upgraded subcooling margin monitors (SMM), upgraded core exit thermocouples (CET), and installation of a reactor coolant inventory tracking system. NRC Regulatory Guide 1.97, which covers accident monitoring instrumentation, was revised (Rev. 3) to be consistent with the requirements of item II.F.2 of NUREG-0737.
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Journal ArticleDOI
TL;DR: In the present work, safety margin uncertainties are handled by Order Statistics (OS) (with both Bracketing and Coverage approaches) to jointly estimate percentiles of the distributions of the safety parameter and of the time required for it to reach these percentiles values during its dynamic evolution.

30 citations


Cites background from "Instrument accuracy in reactor vess..."

  • ...63 Normal Mp2 (Mass of lead in Loop 2) [kg] [4] 56160....

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  • ...24 Normal Mp1 (Mass of lead in Loop 1) [kg] [4] 9469....

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Journal ArticleDOI
TL;DR: In this article, an improvement in current emergency operating procedures regarding how many RCPs should be tripped during SBLOCA sequences is proposed, taking into account Optimal Recovery Guidelines (ORGs) and in the second approach, the transition to Function Restoration Guidelines (FRGs) due to inadequate core cooling (ICC) conditions is considered.

10 citations

Journal ArticleDOI
TL;DR: In this article, a review of reactor coolant inventory tracking systems (RCITS) is presented, and attention is given to operating experience, accuracy, and procedures for the detection of inadequate core cooling.
Abstract: Instrumentation needs for the detection of inadequate core cooling are discussed, and a review of reactor coolant inventory tracking systems (RCITS) is presented. RCITS installation experience is considered, and attention is given to operating experience, accuracy, and procedures. It is noted that the addition of inadequate core cooling accident monitoring instrumentation to all PWRs (pressurized water reactors) is nearing completion after more than eight years. The response of and acceptance by the utilities have been largely positive, with only a few holdouts. It is concluded that the systems developed, while not providing the precision that might be desired, are sufficient to provide vital information for accident avoidance and recovery. In addition, unexpected benefits for normal operation have resulted, and operator acceptance and confidence have been good. >

5 citations


Cites background from "Instrument accuracy in reactor vess..."

  • ...Some of those problems and the current status of industry efforts to achieve a reliable and unambiguous indication of water level were discussed recently in another paper.(8) The possible effects of level measurement uncertainty for a typical small-break transient are shown in Fig....

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Journal ArticleDOI
TL;DR: In this paper, experimental results on the general performances of core exit thermocouples (CETs) to detect core overheat for accident management (AM) action by using the Large Scale Test Facility (LSTF) of the ROSA Program of the Japan Atomic Energy Agency.
Abstract: Presented are experimental results on the general performances of core exit thermocouples (CETs) to detect core overheat for accident management (AM) action by using the Large-Scale Test Facility (LSTF) of the ROSA Program of the Japan Atomic Energy Agency. The LSTF is a full-height, full-pressure, and 1/48-volumetric-scaled model of a 4-loop pressurized water reactor (PWR). This study was motivated by a significant delay in the time and temperature rise of the CETs from core heat-up during a vessel top head small break loss-of-coolant accident (SBLOCA) test. A certain delay in time and temperature rise of the CETs was also observed in various SBLOCA and abnormal transient tests. Such CET performances are derived from thirteen LSTF tests as follows: (1) general CET performances are obtained in the form of equations including cases under limited influences of water fall-back from hot legs, (2) the major reason for the delay is the interaction of three-dimensional steam flows with low-temperature structures...

4 citations