On July 23, 1990, Leonid Kravchuk was elected to replace Ivashko as parliament chairman. On July 30, Parliament adopted a resolution on military service ordering Ukrainian soldiers "in regions of national conflict such as Armenia and Azerbaijan" to return to Ukrainian territory. On August 1, Parliament voted overwhelmingly to shut down the Chernobyl Nuclear Power Plant. On August 3, it adopted a law on the economic sovereignty of the Ukrainian republic. On August 19, the first Ukrainian Catholic liturgy in 44 years was celebrated at St. George Cathedral. On September 5–7, the International Symposium on the Great Famine of 1932–1933 was held in Kiev. On September 8, The first "Youth for Christ" rally since 1933 took place held in Lviv, with 40,000 participants. In September 28–30, the Green Party of Ukraine held its founding congress. On September 30, nearly 100,000 people marched in Kiev to protest against the new union treaty proposed by Gorbachev.