[en] Recorded data for TEST 1205 conducted on the Full-Scale Mark II CRT (Containment Response Test) Facility are presented. The TEST 1205 is the fifth test run of a series of steam discharge pool swell tests. The test conditions are similar to those of the TEST 1203 except that the vacuum breaker was locked close. The test was successful and the comparison of the TEST 1205 and the TEST 1203 results shows that the vacuum breaker may have some effects to reduce the wetwell airspace pressurization, and thus to reduce the upward force to diaphram floor during a pool swell. (author)