https://re.public.polimi.it/bitstream/11311/1020691/1/rev_A%20Dynamic%20safety%20margin%20characterization%20approach%20in%20support%20of%20IDPSA.pdf

A dynamic probabilistic safety margin characterization approach in support of Integrated Deterministic and Probabilistic Safety Analysis

Since the Three Mile Island accident, an important focus of pressurized water reactor (PWR) transient analyses has been a small-break loss-of-coolant accident (SBLOCA). In 2002, the discovery of th...

/pdf/accident-management-actions-in-an-upper-head-small-break-107hjlbjx5.pdf

Accident Management Actions in an Upper-Head Small-Break Loss-of-Coolant Accident with High-Pressure Safety Injection Failed

Effects of RCP trip when recovering HPSI during LOCA in a Westinghouse PWR

The temperature profile of the D2O moderator inside a CANDU (Canada Deuterium Uranium) reactor, within the calandria vessel, was measured by means of a specially instrumented probe introduced within the core. Measurements were made under steady and transient reactor conditions using two different sensors, viz. resistance temperature detectors (RTD) and type K chromel-alumel thermocouples. The results established the feasibility of in-core moderatortemperature measurement and indicated that the thermocouples used were relatively not affected by the intense radiation fields thus producing more accurate data.

In-core moderator temperature measurement within Candu reactors

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. >

/pdf/post-implementation-review-of-inadequate-core-cooling-3lov5ab9uv.pdf

Post-implementation review of inadequate core cooling instrumentation

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.

R.L. Anderson

Papers

Post-implementation review of inadequate core cooling instrumentation

Instrument accuracy in reactor vessel inventory tracking systems

In-Core Thermocouple Performance under Simulated Accident Conditions