Document RpbzNG6j0VozJ3QdyewNZrRea

tconocoj Interoffice Communication To R. A. Conrad from JliD Gibson Dvtv February 8, 1983 Subjvet NEAR BISS INVESTIGATION ON JANUARY 7, 1983 INCIDENT The Investigation team met on February 3, 1983, to discuss the incident concerning VCB escaping In the boiler room whenever Johnny Laster pulled a flat cap to install a valve on the steam main. On the morning of January 7, 1983, I shut B-401 down. It was the practice during the January plant outage to run the boiler at night and shut It down during the day when temperatures were warmer for energy conservation. After B-401 was down, I instructed the panel operator to open the steam ejector valve which depressurized all steam lines. I verified the steam ejector was open whenever I returned to the control room. During the day, several other safety work permits were issued to repair plant steam leaks. I received no feedback about VCM from those mechanics. At 1530, Laster reported to Chris Turner and I that when he had removed the flat cap on the steam main VCM vapors were present in the line. The three of us proceeded to the job site and confirmed the line contained VCM by slightly opening the installed valve. Chris and I walked the steam header, opened several bleeders, and found VCM present In the line. Our investigation ended at F-210 and F-211 which both contained VCM pressure. We blocked the topside steam blowdown line to F-210 and F-211 and opened a bleeder which confirmed the blowdown valves were leaking through. We were also suspicious of the steam stripping supply valves to F-210 and F-211. The steam supply block valve to the V-20 area was then closed which permitted the rest of the plant steam lines to clear out via the steam ejector. The four iteam valves' on F-210 and F-211 were replaced during the week of January 10th. Basic Cause of Incident The migration of VCM vapors from F-210 and F-211 into the depressurized steam header. That condition was the result of worn seats in the steam blowdown and steam stripping valves in F-210 and F-211. Underlying Cause of Incident F-210 and F-211 were not blinded. In planned plant shutdowns, the only VCM in the V-40 area is contained in one recovered VCM receiver and blinded. DTH 000098943 R. A. Conrad February 8, 1983 Page Two In the V-20 area, one stripping tank will always contain VCM pressure during a shutdown If the system is taken out of service properly. The outlet line off F-214 Is then blinded to block the entire V-20 system from the V-40 recovered VCM receiver. The nature of some of the work during the January outage deviated from past shutdown practices. Recommendations and Conclusions 1) Leak check F-210 and F-211 steam blowdown and steam stripping valves once a month. This program has already been implemented through the production department work calendar. 2) Blind the stripping tank (F-210/211) that has pressure on it during shutdowns. The dump line, topside vapor header, and steam line will require blinding along with the fill line and F-214 outlet line. 3) Stroke and leak check all newly installed actuated valves. Process Superintendent Dave ourr Maint. Supv. oui.cn i-tccuoi 1st Class Mech. Jiff Gibson Shift Supervisor Team Leader DTH 000098944