Neutron damage

Fig. 18. Tritium retention as a function of neutron damage tn graphite and graphite composite.

Birch, M., Schofield, P., Brocklehurst, J.E., Kelly, B.T., Harper, A. and Prior, H., The combined effects of fast neutron damage and radiolytic oxidation on the physical... 

The authors speculate that the observed effect of standing or heating involves a reaction of species such as FeCp with an additional Cp formed during the irradiation by the recoil of the Fe atom or by fast neutron damage. 

L. R. Greenwood and R. K. Smither, SPECTER Neutron Damage Calculations for Materials Irradiations, ANL/FPP-TM-197, 1985. 

Zirconium s major use is as cladding for nuclear reactors. It is ideal for this use, as it has a hmited ability to capture neutrons, strength at elevated temperatures, considerable corrosion resistance, and satisfactory neutron damage resistance. Almost all ores of zirconium contain about 2 percent of zirconium s sister element, hafnium (Hf). Hafnium readily absorbs neutrons and therefore must be completely separated and removed from zirconium before either element can be used in nuclear reactors. A major task of the Manhattan Project was the separation of hafnium from zirconium. The elements are the two most chemically similar in the Periodic Table. The recovered hafnium metal is used to make the control rods of nuclear reactors, as the metal readily absorbs neutrons. 

TABLE 2.THE DEPTH OF FUEL BURNING UP, FAST NEUTRONS DAMAGING DOSE, MICROCAMPAIGN AND CAMPAIGN DURATION AS THE FUNCTIONS OF MAKE-UP FUEL ENRICHMENT... 

In the case of using metal alloyed (10% of Zr) uranium fuel with 75% effective density of theoretical one, the reactor can utilize waste uranium as the make-up. Thus the highest EUU is ensured (about 20%). In this case the bum-up depth achieves about 20% of h.a. (that is justified at experimental assemblies of EBR-2 reactor), fast neutron damaging dose on the fuel element cladding material accounts for approximately 430 dpa (it is twice the value that has been achieved by tests for ferritic and martensitic steels), the total operation period of FEA is about 30 years (that is three times over that gained for RI operation at the NS). 

Other vessels located in the containment, such as the pressurizer and the steam generators, might also potentially damage various barriers at the same time, but this probability is intrinsically lower than that of the reactor vessel as they are more distant from the core (it can be lowered by provisions concerning the strength of the structures and because they are not exposed to neutron damage and can more easily be inspected during service). 

J.C. Van Dnysen, J. Bonrgoin, P. Moser and C. Janot, Study of the neutron damage in a PWR pressure vessel steel after long-term irradiations in the Chooz A Reactor Surveillance Programme , Radiation Embrittlement of Nuclear Reactor Pressure Vessel Steels An international review (4th Volume), ASTM STP1170, L.E. Steele, ed., American Society for Testing and Materials, Philadelphia, PA, 1993,132-138. 

X 10 cm sec and the neutron and gamma energy fluxes to 2.5 X 10 and 1.8 x 10 MeV/cm sec, respectively. The temperature in the superconductor rises at 0.2 K/hr, allowing operation for the order of a day in this non-optimized design. Neutron damage was also assessed less than 1% change in resistivity was expected after one year. 

If p/B reactors are developed, it appears that they will be "radiation dominated"[24]. This will require new approaches to both blanket design and energy extraction. Such a reactor could potentially overcome the power density limitations imposed in current D-T concepts by neutron damage to the first wall and bl anket. 

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