CA Penal Code Section 901

(a)

The persons whose names are so returned shall be known as regular jurors, and shall serve for one year and until other persons are selected and returned.

(b)

If the superior court so decides, the presiding judge may name up to 10 regular jurors not previously so named, who served on the previous grand jury and who so consent, to serve for a second year.

(c)

The court may also decide to select grand jurors pursuant to Section 908.2.