CRUD in PWR/VVER Coolant Volume II – Control of CRUD in the PWR/VVER Coolant and Mitigation Tools

(LCC11 STR)
All materials used in nuclear power plants, as bare material (steels and alloys), are not stable in the reactor water and dissolve by corrosion. They are protected by passive oxide layers formed by the corrosion attack of the water to the metal surface under operating conditions. However, to some small extent these oxide layers dissolve in the reactor coolant and are transported as corrosion products (called also CRUD) to the reactor core. There they deposit on the fuel assemblies and are activated. The deposition of the crud on fuel assemblies and their release to the coolant highly influences the core and plant performance with respect to fuel cladding integrity and radiation fields.

The purpose of the Volume II of this Report, in LCC11, is to describe the tools and their application to adequately control the coolant crud in order to improve the fuel and out-core radiation performance. This information can support the plant chemists to establish strategies of applying the mitigating tools for crud control to achieve their plant specific goals. The information given in this Report is also valuable for fuel vendors and plant fuel engineers to evaluate the possible ways of improving the fuel performance. In a similar way, this information helps the Regulators at properly examining the relative importance of various CRUD Control Mitigating Tools to ensuring an improved fuel performance for safe operation. 
The associated Volume I containing: Mechanism of Sources, Transportation in Coolant, Fuel Deposition and Radiation Build-up, was published within the LCC10 Programme.

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Start-Up and Shutdown Practices in BWRs as well as in Primary and Secondary Circuits of PWRs, VVERs and CANDUs

The objective of this Report is to provide a good understanding of the special problems and appropriate good practices during shutdown as well as during startup of LWRs. The Report provides a worldwide review of Startup and Shutdown Procedures both in the Primary and in the Secondary Circuit of PWRs, CANDUs and VVERs, and in the reactor coolant and main steam containing systems of BWRs.

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LCC9 AR: Operational Issues, Practices and Remedies

Operational Issues, Practices and Remedies are important issues for plant personnel and designers. This report combines the following subjects of limited extent but potentially important consequences:

  • Degradation of the primary coolant barrier together with mechanical remedies.
  • The potential benefits of Enriched Boric Acid (EBA).
  • Primary coolant (Co-58, colloids) inventory.
  • Degradation of concrete structures in NPPs.
  • Colloids, Zeta Potential and Activity Transport.
  • Electrochemical Corrosion Potential (ECP) measurements.
  • Key points, ”lessons learned” and ”best practices” of several recent conferences.

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CRUD in PWR/VVER Coolant. Volume I – Sources, Transportation in Coolant, Fuel Deposition and Radiation Build-Up

Crud in PWR/VVER Coolant. Volume I – Sources, Transportation in Coolant, Fuel Deposition and Radiation Build-up (LCC10 STR) The topic is covered in two separate volumes. Volume I which is provided within the LCC10 Programme, and Volume II which will be provided in the LCC11 Programme. This document, Volume I covers the following topics:

  • Introduction
  • Sources of CRUD
  • CRUD Transportation in PWR/VVER Coolant
  • Crud Deposition in the Core
  • Crud Release from Core and Radiation Build-up Mechanism
  • Summary Volume II will contain information on Control of CRUD in the PWR/VVER Coolant and Mitigation Tools

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Key Emerging Issues and Recent Progress Related to Plant Chemistry/Corrosion

(LCC8)
The report covers the impact of manufacturing on microstructure and in-reactor performance of Zr-Nb alloys. The report was co-authored by Russian scientists involved in the development of the Russian Alloys E110, E635 and E125.

1. The EPRI Steam Generator Secondary Side Management Conference covering:
  • Deposit generation and transport
  • Deposit control and mitigation
  • Deposit consolidation and removal
  • Short and long term strategic planning
2. BWR issues presented in the EPRI Conference
3. The Nuclear Power Chemistry Conference covering:
  • Primary water chemistry including:
  • Secondary water chemistry including:
  • Auxiliary systems, cooling water systems, water and waste treatment
  • Lifetime management and plant ageing
  • Maintenance including curative and preventive cleaning methods
  • Future trends and new developments

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Incoming Goods, Hazardous Materials and Aging of Plant Chemicals

The objective of this Report is to provide a comprehensive understanding of controlling the quality of incoming goods in Nuclear Power Plants. The Report will help utilities with checking that their Quality Assurance system is appropriate or modifying it. The Report will also be useful for manufacturers at properly implementing manufacturing, protection, shipping, labelling, etc for avoiding degradation that may be discovered at the very beginning of plant operation. Finally, regulators will have a complete view of the possible risks of degradation and how to verify that the Quality Assurance programs are implemented.

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Operational Issues and Practices in PWRs

Operational Issues and Practices are important issues for plant personnel. These issues may require optimization or an exchange of knowledge to improve plant operation in a safe, economical, environmentally sustainable way. This report combines the following topics of potentially important consequences:

  • Total Organic Carbon (TOC) in primary and secondary system water
  • Best practices for corrosion products removal in reactor coolant systems (RCS) of VVERs and the use of mechanical filters or macroporous resins
  • Best practices for the use of Ion Exchange Resins for RCS, SG blowdown, and the spent fuel pool
  • Best practices to mitigate condenser leakages and recommendations for Operation procedures in case of large impurities ingress
  • The Use of Dispersant to Mitigate Steam Generator Corrosion Product Deposition In addition to the help for utilities, this report may be of interest for manufacturers and regulators in understanding some plant issues.

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PWR and VVER Secondary System Water Chemistry

Adequate secondary side water chemistry is crucial for safe and economical PWR and VVER plant operation. A good practised water chemistry control avoids degradation problems of the key components, sucj as steam generators (SG), carbon steeel components and turbine. The PWR and VVER Secondary System Water Chemistry Report gives a complete overview of the various rationale approaches to optimize the water chemistry according to the design and materials as well as the specific situation of each Nuclear Power Plant.

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PWR/VVER Primary Side Coolant Chemistry, Volume II – Water Chemistry Tool to Mitigate the Concerns

(LCC8 STR)
This report is the second volume out of two focusing on PWR/VVER chemistry. Volume II covers the following topics: Chronology of Coolant Chemistry, Current Coolant Chemistry Programs, Coolant Chemistry Guidelines & Practices, Purification and Filtration of the Coolant Monitoring Concept.

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