Reactor operating histories

Known or estimated reactor operating histories of the seven nuclear submarines and icebreaker are detailed in the following sections. 

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The following sections detail what is currently known or estimated about the seven nuclear submarines and icebreaker with respect to the characteristics of their SGIs, their reactor operating histories, their radionuclide inventories, and their disposal operations. 

Quantity of these materials and their radioactivity shall be evaluated before decommissioning starts based on the real reactor operation history. 

Figure 87. Predicted accumulated damage for IGSCC (crack length) in a Boiling Water Reactor as a function of the reactor operating history over ten years and as a function of the water chemistry protocols employed. Reprinted from Ref. 9, Copyright (1995) with permission from Elsevier.

The tire analysis was assisted by SNL using methods described in NUREG/CR-4840 and the extensive operating history and fire experience. For 94 reactor-years from 1958 and 1987, 20 significant fire events were recorded. Hence, frequencies for the reactor building and the diesel generator buildings of 0.12 and 0.03 /y, respectively. A control room fire has never occurred at a SRS reactor. 

The work on the electrochemical generation of a solution of ceric sulphate from slurry of cerous sulphate in 1-2 M sulphuric acid was abandoned by BCR due to difficulties encountered in handling slurried reactants. A 6kW pilot reactor operated at 50 °C using a Ti plate anode and a tungsten wire cathode (electrolyte velocity about 2ms 1) produced 0.5 M Ce(S04)2 on the anode with a current efficiency of 60%. The usefulness of Ce(IV) has been limited by the counter anions [131,132], Problems include instability to oxidation, reactivity with organic substrates and low solubility. Grace found that use of cerium salts of methane sulfonate avoids the above problems. Walsh has summarized the process history, Scheme 6 [133],... 

Spent fuels vary in microstructure, and phase and elemental distribution depending on the in-core reactor operating conditions and reactor history. The chemical stability of spent U oxide fuel is described by local pH and Eh conditions, redox being the most important parameter. However, the redox system will also evolve with time as various radionuclides decay and the proportion of oxidants and reductants generated at the fuel/water interface changes with the altering a-, (J-, y-radiation field and with the generation of other corrosion products that can act as... 

Hoyle JC. Fitness-for-duly programs. Fed Reg 1988 54 24468-508. (http //www.nrc.gov/reactors/ operating/ops-experience/fitness-for-duty-programs/ history.html)... 

Figure 4. Operation history during the high-temperature test operation by the single-loaded mode. Maximum reactor-outlet coolant temperature of 950°C had attained on 19 April 2004.

Figure 4. Glucose and pH histories in the effluent during the course of the dual hollow-fiber reactor operation. - o -, — - glucose cone., -A-, -A- pH. The filled circles and triangles represent the effluents containing E. coli cells.

The operating data and history of the JOYO MK-II core are shown in Table 2 and Fig. 3. The reactor operated for 48 000 hours and the integrated power generated was 4 400GWh. During the MK-II operation, 382 driver fuel subassemblies and approximately 47 000 fuel pins were irradiated. A peak burnup value of 86.0 GWd/t was attained for the MK-II driver fuel without any fuel pin failures. 

It is possible that this peculiarity of rod insertion was the final mechanism for the prompt critical accident. The calculation of the size of the effect depends upon assumptions about the previous operating history of the reactor, but estimates made at the Berkeley Nuclear Laboratory suggest that this final water displacement may have added between Vi% and Vi% reactivity, enough indeed to bring about the prompt critical excursion. 

Prediction of the oxide build ip on reactor conponents r quir s a knowledge of their chemical ccsrposition and tenperatvar history, and also of the coolant conposition. The operating history of the reactors is well documented but there was no information about the taiperature distribution in the core restraint annulus or its relationship to the hot gas duct tenpenature. Thermocouples fitted since reactor ccximissioning (Reference 1) have Indicated an uneven distribution with hot aresis renote from the hot gas outlet ducts. 

Figure 2.1 Operating History of Experimental Fast Reactor JOYO...

Six of the seven nuclear submarines contained two pressurized water reactors (PWRs) each. Eleven of these PWRs were dumped into the Kara Sea between 1965 and 1988 eight within and three without their reactor compartments (RCs). AH these nuclear submarines suffered some form of reactor accident however, many specifics of the reactor design, maximum thermal power, compartment layout, detailed operating histories, and accident scenarios remain classified. 

The danger of errors in the experimental determination of the thermal neutron fluence caused by other nuclear reactions is small. Co is also produced in stainless steels by (n,p) reaction from Ni and by (n,a) reaction from Cu, with both reactions being induced by fast neutrons. Since the cross sections of both reactions are very small (5 10 cm and 4.2 10 cm respectively), no interference is to be expected in light water reactors when monitor materials of the usual purity are used. Due to the 5.28-year halflife of Co, details of the irradiation history of this monitor material can only be neglected at gross irradiation periods of up to one year for longer periods, interruptions in the operation history of the plant, such as shutdowns, load reductions etc., have to be corrected for. 

The chemical composition and the structure of the contamination layer oxides in the primary systems depend highly on the reactor type (PWR, BWR) and also on the operational history of the plant. The optimum decontamination process to be applied, therefore, must be selected and, if necessary, optimized to meet the task in question. In particular, when components and systems are to be decontaminated, different structural materials and, consequently, oxide layers of different composition are involved, resulting in more stringent demands on the decontamination procedures to be applied. 

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