For operational control and accounting purposes, the station requires a system which monitors the loca­tion and condition {i. e., irradiation, rating, dwell time, etc.) of all fuel on site, whether in the reactor, store or ponds. In addition, the station site licence and international regulations impose formal requirements. In order to fulfil all the various needs and obliga­tions, comprehensive record-keeping systems have been developed and at each station the systems fall into two categories. Firstly, a iocat fuel route paperwork system ensures adequate standards of control over the various fuel movements, thereby involving an amount of recording and checking. Secondly, a highly sophis­ticated computer-based system, in addition to record­keeping, provides other importance information such as calculated isotopic content data of irradiated fuel elements prior to their despatch from site. This in­formation is required by BNFL and also by Euratom and the International Atomic Energy Agency in sup­port of international safeguards work. Also contained within the computer-based record system is fuel cost data which is regularly updated so as to assist the CEGB in meeting its obligation to supply electricity economically.

8.4.1 Fuel records system

In order to apply administrative control over the han­dling and movement of fuel within the fuel route, more than 60 forms have been designed for use at the job. This paperwork constitutes the fuel route record system in which the important fuel manoeuvres may only take place following the issue of the rele­vant form, suitably authorised by approved signatories. Many of the forms require certain checks and re­cords to be made at given limes during the different operations. The diversity and complexity of this paper­work system is far too detailed to w-arrant a full description here, but it is nevertheless important that its existence and overall objectives are understood. The life of each fuel element, once it has been re­ceived on site, is also monitored and recorded by com­puter at the CEGB’s computing centre in London, using a complex programme called FULER. This par­ticular programme is part of a much larger suite of programmes known as ADOS (AGR Data Operating System), the function of which is to model each re­actor core as irradiation accrues and refuelling takes place so that various operating parameters such as can temperatures, channel powers and element irra­diations can be calculated. Although FULER per­forms several functions within this larger network, the maintenance of fuel records is its main task and much of the data required by the program is extracted from the fuel route paperwork system just described. FULER performs its record updating by using a sim­plified computer model of the fuel route so that elements are moved, within the records, between fuel store, reactor channels, buffer storage tubes, and skips in the ponds from which they are eventually des­patched in flasks, all movements taking place soon after they actually happen in practice. This is achieved
by specifying within each FULER run, details of re­fuelling, stringer dismantling and other fuel move­ments as soon as the relevant information becomes available from the fuel route paperwork system.

As also happens with magnox fuel records (NFER), FULER will provide an isotopic inventory (i. e., ura­nium and plutonium isotopic weights) for discharged fuel, according to its initial enrichment and the irra­diation it has received. Once a skip has become fully loaded within the records, the program automatically computes the necessary information for the entire skip contents by referring to the isotopic data which is stored elsewhere. A packing sheet is then generated showing the isotopic weights for each element in the skip.

At approximately monthly intervals during reactor life, all the FULER files comprising the fuel records are interrogated via a powerful information system so that routine checks and printouts can be made of the contents of the different parts of the records. Comparisons are then made with the results of a physical count (audit) of fuel elements at the various locations on the station to ensure that the records system is accurate. Typical data stored for each ele­ment within the records include identification number, reactor channel and axial position, uranium weight, discharge irradiation, loading and discharge dates.