A method for controlling fluid leakage in a high pressure feeder of a feed system, comprising: obtaining, from a plurality of flow meters (130, 134, 136), a plurality of flow values, including a make-up liquor flow value specifying a flow of make-up liquor to a digester, a black liquor flow value specifying a flow of black liquor to the feed system, a white liquor flow value specifying a flow of white liquor to the feed system, a chip chute circulation flow value specifying a flow of low pressure circulation liquor from a low-pressure outlet of the high pressure feeder, and a high pressure feeder purge flow value specifying a flow of white liquor into a high-pressure inlet of the high pressure feeder; obtaining, using a chip speed encoder, a chip speed specifying a speed at which wood chips are provided to the high-pressure feeder; determining, using the chip speed, a chip flow value specifying a flow of chips provided to the high-pressure feeder; determining, using the plurality of flow values and the chip flow value, a fluid leakage value specifying an amount of fluid leakage through an annular gap between a pocket rotor and a chamber of the high pressure feeder, wherein determining the fluid leakage value comprises computing a sum of the black liquor flow value, the white liquor flow value, the chip chute circulation flow value, and the high pressure feeder purge flow value, and reducing the make-up liquor flow value by the computed sum to obtain the fluid leakage value; determining that the fluid leakage satisfies a threshold leakage value; and in response to determining that the fluid leakage satisfies the threshold leakage value, adjusting the annular gap between the pocket rotor and the chamber. obtaining, from a plurality of flow meters (130, 134, 136), a plurality of flow values, including a make-up liquor flow value specifying a flow of make-up liquor to a digester, a black liquor flow value specifying a flow of black liquor to the feed system, a white liquor flow value specifying a flow of white liquor to the feed system, a chip chute circulation flow value specifying a flow of low pressure circulation liquor from a low-pressure outlet of the high pressure feeder, and a high pressure feeder purge flow value specifying a flow of white liquor into a high-pressure inlet of the high pressure feeder; obtaining, using a chip speed encoder, a chip speed specifying a speed at which wood chips are provided to the high-pressure feeder; determining, using the chip speed, a chip flow value specifying a flow of chips provided to the high-pressure feeder; determining, using the plurality of flow values and the chip flow value, a fluid leakage value specifying an amount of fluid leakage through an annular gap between a pocket rotor and a chamber of the high pressure feeder, wherein determining the fluid leakage value comprises computing a sum of the black liquor flow value, the white liquor flow value, the chip chute circulation flow value, and the high pressure feeder purge flow value, and reducing the make-up liquor flow value by the computed sum to obtain the fluid leakage value; computing a sum of the black liquor flow value, the white liquor flow value, the chip chute circulation flow value, and the high pressure feeder purge flow value, and reducing the make-up liquor flow value by the computed sum to obtain the fluid leakage value; determining that the fluid leakage satisfies a threshold leakage value; and in response to determining that the fluid leakage satisfies the threshold leakage value, adjusting the annular gap between the pocket rotor and the chamber.