MCO Monitoring Plan

Abstract

The basis for development of the Multi-Canister Overpack (MCO) Monitoring Plan was established in HNF-3312, MCO Monitoring Activity Description (Sexton 1998), with the following specific objectives: The safety of Spent Nuclear Fuel (SNF) Project processes for retrieving, packaging, handling, conditioning, and storing the N Reactor spent nuclear fuel has been demonstrated by conservative analyses, as compiled in the project safety basis and licensing documentation. Appropriate quality assurance and independent checking of engineering, fabrication, and construction are being applied, and there will be in-process monitoring and verification of MCO loading and conditioning actions. Once the MCOs have been placed in storage, there is no safety requirement, regulatory requirement, or precedent to monitor them. Although not required, a monitoring program which would acquire data for use by Process Engineering is considered valuable for several reasons (Sexton 1998): Good engineering practice--Acquiring data at a reasonable cost that may be useful in developing a fuller understanding of the behavior of an engineered system is good engineering practice. Actual data on full scale MCOs is otherwise unavailable--Previous investigations have been limited to small fuel samples or simulant prototypes and have been relatively short in duration. MCO monitoring can provide data on large loads of actual fuel, in full-scale configuration, over longer time periods. Additional knowledge of the fuel type may prove valuable in future analyses or applications. On that basis, a program with two components was planned: The pressure/temperature/gas composition relationships will be observed in a limited number of MCOs during the first two years in storage. The remaining MCOs will incorporate a simple means to confirm at any time in the future, that internal pressure of the MCO is not high enough to threaten its structural integrity. The MCOs are likely to be stored for 40 years or longer. While routine checking of high pressure indication is not required or anticipated, the capability would always be available and is likely to be used prior to MCO handling and transport. Monitoring is to be kept practical and cost effective such that it will not interfere with the fundamental project objective of putting the spent fuel in a safe configuration away from the river. Significant work has be done to implement these objectives, and this MCO Monitoring Plan will describe the results of this and provide the basis to complete its integration into all required SNF Project documentation.