[en] India has achieved competency in design, construction, commissioning and operations of pressurized heavy water reactor and has completed more than 250 reactor operating years with extremely satisfactory safety record. In this paper, the ageing management of critical reactor component is discussed. The ageing effects of end shield, coolant channels, and feeder pipe were measured and analysed. The data collected from various NDT diagnostic techniques were analysed. Remedial action were innovated, developed and incorporated, which assured safe operation of RAPS- 1 and 2. (author)

[en] A theoretical model has been developed to predict the critical length and thickness of the crack-tip hydride platelets forming during delayed hydride cracking (DHC) in zirconium alloys. The model is based on the analysis of tensile stresses ahead of the sharp crack. (author)

[en] Time response characteristics of an RTD in installed condition may vary due to changes in physical and thermal properties caused by various factors such as ageing, temperature, vibration, flow velocity etc. This calls for the need to carry out in-situ tests to obtain the time response characteristics of the RTD at regular intervals. The loop current step response test is suitable for in-situ time response testing of RTD. In the paper it has been shown how the LCSR test can be conducted to obtain time response of RTD. The time response characteristics obtained by carrying out the plunge test and the LCSR test on a typical RTD at various temperatures and in different fluids have been presented and compared. (author)

[en] The pressurized heavy water reactors in India have demonstrated high reliability during the several decades of reactor years of operation. One of the life limiting components of the reactor is the coolant channel assembly, which is designed to be replaced. This paper dwells on the various changes in the scheme and procedures proposed during the coolant channel assembly replacement in Indian PHWR's

[en] PHWR coolant channels are required to be inspected periodically to satisfy the regulatory requirement, to provide information about known or suspected problem and to provide information to assist in future design. This paper describes these tools and techniques, their capabilities and experience of implementing these in reactor site

[en] Deuterium pick up by the zircaloy coolant channels of PHWRs is one of the factors for assessing its life expectancy. This paper describes in detail the results obtained in the estimation of deuterium content in the silver samples of a few Indian PHWR coolant channels. (author)

[en] Fibre-reinforced-polymer-composite material has been suggested as a bearing material to overcome tribological problems witnessed during the testing of Ram assembly of the 540 MWe fuelling machine at RTD. After successful trials at B-Ram the composite material has been adapted for B-RAM, C-Ram and RDB head at fuelling machines being tested at RTD, Hall 7 and at Tarapur. Laboratory evaluations were also carried out at Tribology Lab RTD to study effect of radiation on the composite. Paper deals with the various aspects of life prediction of this material in term of wear and radiation damage. (author)

[en] Heavy Water Plants are basically chemical plants similar to petrochemicals and fertilizer plants handling hazardous fluids such as ammonia and hydrogen sulphide and operating at pressures ranging from 20 kg/cm² to around 250 kg/cm². The operating temperatures also vary from -33degC to 700degC. Due to the extreme operating conditions, the pressure components of HWPs is likely to undergo degradation i.e. aging. This paper discusses the aging of pressure components in HWPs and the various destructive and non-destructive examination techniques being used to assess the extent of aging. These tests are being carried out as a part of in-service inspection activities based on code of practice for Inservice Inspection (ISI). Results obtained thereof are compared to assess the health of the components. Some case studies also have been discussed. (author)

[en] Fail-safe design criteria like Leak-Before-Break (LBB) based on fracture mechanics methods are being used to ensure the safety and integrity of components under operational and extreme loading conditions. This paper deals with Level II of LBB evaluation. Detailed experimental studies were conducted on 15 circumferentially cracked carbon steel pipes of SA 333 Grade 6 material used in Indian PHWRs. The results of the studies are discussed in this paper. (author)

[en] Water hammer can be disastrous from the point of view of ageing of the pipe(s)/Piping system. Design of restraints and protection devices for the various piping systems must consider severe stresses that may generate because of fluid transients. These fluid transients are termed as water hammer when it is restricted to water. But to have limited margins on the stress loads of piping system it is very important to predict the actual dimensions of the stresses. This paper covers various causes and analyses of the situations under which water hammer waves get generated and also way(s) to have control on occurrences of such situations. Few case studies are also covered showing the results and graphs of the stress waves generated because of water hammer. Effort has also been made in the paper in the direction to find out the methodology to compute the ageing of the system because of water hammer waves. Further in this paper an attempt is made to show the systematic methodology towards the diagnosis of water hammer that can be treated as a foundation stone for the creation of water hammer diagnosis system. Active measures to minimize the water hammer intensity by influencing fluid dynamic conditions of the system will also be suggested. Finally the paper will present the ageing aspects because of the stresses that generate due to water hammer. (author)