[en] Ambient and higher temperature tensile properties and also hardness properties of irradiated (I) and irradiated, annealed, re-irradiated (IAR) reference pressure vessel (PV) steel are presented. Spectrum-tailored pressurized light water reactor (PWR) irradiation at 290^oC by fast neutrons up to fluences of 5x10¹⁹/cm² in a swimming-pool-type reactor caused the hardness, tensile yield stress and tensile strength to increase. The ductility, as measured by the specimen elongation in the tensile test, was also slightly affected. The response to an intermediate annealing treatment using 460^oC x 18 hr, when 50% of the target fluence had been reached, was monitored using hardness measurements and determining the tensile properties. Annealing was beneficial in mitigating the accumulation of embrittlement effects as detected by the smaller changes in mechanical properties for the IAR condition relative to those found in the I one. The rate of re-embrittlement after annealing and re-irradiating was not detected as being any faster than when no intermediate anneal had been performed. The temperature dependence of the annealing process was quantified by assuming a first-order reaction and using an Arrhenius-type analysis. The activation energy for the recovery of the Vicker's hardness (HV 0.2) was approx. 250 kJ/mol. Annealing temperatures below 420^oC were seen to require excessively long times, i.e. > 168 hr to achieve a reduction in radiation-induced hardness. The benefit of an intermdiate PV annealing treatment has been demonstrated on a laboratory basis to be a useful tool in the overall strategy for plant life management options. This assumes, of course, that PV would be the life-limiting component. (author) 6 figs., 4 tabs., 5 refs