Document K5KKJy2m0bo8Rbo11aYn3az6

Personnel ^ Interviews iX t uo A 029741 co nfidential Chi r-Alkali II Plant Personnel Reactive Chemical Interview Questi ns 1. (A) A LOSS OF ANOLYTE LEVEL IN THE CHLORINE CELLS WOULD RESULT IN WHAT REACTIVE CHEMICAL CONCERN? (B) WHAT ARE THE PREVENTATIVE MEASURES TO AVOID THIS? Correct OS SOS (A) A chlorine/hydrogen explosion. 1/1 1/1 (B) - Generator trips at 2.5 inch level. Y - 2 level transmitters and low level carbon probe - critical instrument. Y - Mod 5 voting logic (2/3, 2/2,1/1) - but not carbon probe. 2/2 2/2 YY 2. HOW IS HYDROGEN BACKFLOW FROM THE HYDROGEN COLLECTION SYSTEM TO THE CELLS PREVENTED? Correct OS SOS 1/1 2/2 - Discharge EBV closes upon hydrogen compressor trip. Y - T-206 will vent gas in train. Y YY - Individual stacks at cells backup T-206. Y YY 3. (A) WHAT WOULD HAPPEN IF OXYGEN GOT INTO THE HYDROGEN HEADER? (B) WHAT ARE THE PREVENTATIVE MEASURES TO AVOID THIS? Correct OS SOS 1/1 2/2 (A) An explosion would occur (a "pop," if minor in nature). Y YY 0/1 1/2 (B) - Nitrogen purge activated in startup/shutdown steps for the Y YY hydrogen stacks. - Low nitrogen flow alarm at 200 Ib/hour (normal rate 500 Ib/hour). Y - Nitrogen valve position alarms. - Hydrogen compressor shutdown -1.5 INWA instantaneous or 1/8 Y INWA for 2 seconds. - Standard operating procedure to "bottle" series on all shutdowns (purges the cell with brine). - Off-line procedures for cell maintenance. - Ceil sprayers and housekeeping. 4. (A) WHAT WOULD HAPPEN IF THE 2ND/3RD STAGE CHLORINE COMRESSOR DISCHARGE TEMPERATURE GOT TOO HIGH? (B) HOW IS THIS PREVENTED? Correct OS SOS (A) A chlorine / iron fire. 1/1 2/2 1/1 2/2 (B) - Compressor trips at 325 degrees F on either stage. Y YY - Triple redundant temperatures on each stage. Y YY - Mod 5 voting logic. JGS 2/6/97 Do C-OMf A 02976/ 5. WEAK H2S04 IS VERY CORROSIVE WHEN CONTACTED WITH STEEL. HOW ARE THE DRYING TOWERS PROTECTED FROM CORROSION? Correct OS SOS 1/1 2/2 - The first drying tower, T-201, is a CPVC lined vessel. Y YY - Acid strengths / flows / temperature are monitored in both drying towers. Y Y - Tray temperatures are monitored in both towers. YY 6. HOW IS A NITROGEN TRICHLORIDE EXPLOSION IN THE TAFFY POTS PREVENTED? Correct OS SOS 1/1 2/2 - Monitor and alarm temperature in each pot (redundant). Y YY - Alarm rate of temperature rise in pots. Y - Analyze brine for NH3 content weekly at GBO. - Analyze taffy bi-weekly for NCI3. Y YY - Monitor and alarm pressure on each pot (redundant). Y - Lowered PSV setting to 150# to catch pot overpressure. Y - Maintain 40 ppm /150 ppm hypochlorite in the brine at Chlorine 1. - Maintain level below 40% to allow room for diluent should a reaction occur. Y Y - Capability to automatically add liquid chlorine to the taffy pot in the event Y YY of a reaction. Also have capability to add CCI4 to pots. - Reboiler temperature controlled to decompose NCI3. Given 40 psig YY operating pressure, reboiler temperature set point is 170 degrees F, over 30 degrees below the boiling point of diluent, CCI4. - Pressure transmitter and an alarm for high pressure "rate of rise" on - transfer line. 7. WATER / MOIST AIR ENTERING THE LIQUEFACTION PROCESS FROM BRINE SCRUBBER WILL CREATE A SEVERE CORROSION PROBLEM. HOW IS THIS PREVENTED? Correct QB BQB 1/1 2/2 - Check valve installation on tail gas line to scrubber. Y - High pressure alarm on brine scrubber. YY - Moisture analyzer and alarm on T-505 tail gas inlet line. YY - Liquefaction startup and shutdown procedures, on computer, call for Y blinding the liquefaction process from the brine scrubber when liquefaction is to be depressured. 8. HOW IS NCI3 ACCUMULATION IN THE EVAPORATOR BOTTOMS PREVENTED? Correct QB BQB 1/1 2/2 Flush evaporator bottoms once daily to T-204. Y YY JGS 2/6/97 0 A 02974 >5 ^ONriD^NTTAl. 9. WHAT CONCENTRATION OF HYDROGEN CAN FORM AN EXPLOSIVE MIXTURE WITH CHLORINE? Correct Q SOS 1/1 2/2 >4% Y YY 10. (A) IF CHLORINE GOT INTO THE FREON SYSTEM, WOULD THERE BE A REACTION? (B) WHY? Correct OS SOS (A) Yes. 1/1 2/2 1/1 2/2 (B) Even though Freon is not specifically reactive with chlorine, the Y YY Freon system often contains trace levels of oil/organic compounds which are reactive with chlorine. 11. WEAK SULFURIC ACID <95% AND CONCENTRATED SULFURIC ACID >98% REACT VIOLENTLY WITH STEEL AND OTHER METALS. WHAT ARE THE 2 CONCERNS OF THIS REACTION? Correct QS SOS 1/1 1/2 Severe corrosion and evolution of flammable hydrogen gas. YY 12. WHICH OF THE FOLLOWING ARE REACTIVE? (A) Wet chlorine + steel yes (B) Wet chlorine + titanium no (C) Dry chlorine + titanium yes (D) Chlorine + ammonia yes (E) Chlorine + pure Freon no (F) Chlorine + organic compounds yes (G) Hydrogen + oxygen yes (H) Sulfuric acid + organics yes (1) Oxygen + greases yes (J) Chlorothene + copper-containing compounds yes Correct OS SOS 1/1 2/2 Y YY Y YY Y YY Y YY Y YY Y YY Y YY - Y YY Y YY Y YY OS scored 96 % correct. SOS's scored 92 and 96% correct. JGS 2/6/97 A 029746 cSfio^tial Caustic Plant Personnel Reactive Chemical Interview Questi ns 1. WHAT IS THE REACTIVE CHEMICAL CONCERN OF MIXING CAUSTIC WITH ACIDS LIKE SULFURIC AND HYDROCHLORIC ACID? Correct Caustic reacts violently/explosively with acids. OS 2/2 1/1 2. WHAT ARE SOME METALS THAT REACT RAPIDLY WITH CAUSTIC? Aluminum, tin, copper, zinc, bronze, brass. Correct Q SOS 2/2 1/1 3. (A) WHAT IS THE REACTIVE CHEMICAL CONCERN OF MIXING 50% CAUSTIC AND WATER? (B) SHOULD CAUSTIC BE ADDED TO WATER, OR WATER TO CAUSTIC? Correct QS Q (A) Exothermic heat of dilution.. 2/2 1/1 (B) Add caustic to water 1/2 1/1 4. UNDER WHAT CONDITIONS DOES CAUSTIC REACT RAPIDLY WITH STEEL? Correct At elevated temperatures (120 - 150 degrees F) 2/2 1/1 5. HOW IS CONTAMINATION OF THE UTILITY SYSTEMS PREVENTED? Double block and bleeds used at all cross tie points. Correct OS Q 1/2 1/1 6. HOW IS CORROSION OF NICKEL CLAD VESSELS BY HYPOCHLORITES IN THE CELL EFFLUENT FEED PREVENTED? Correct Cell effluent is analyzed for hypochlorites. Hypochlorites are neutralized with sodium bisulfite. 1/2 1/1 7. WHAT ARE THE CONCERNS OF WELDING ON PIPING AND EQUIPMENT CONTAINING RESIDUAL CAUSTIC? Correct Embrittlement, stress cracking, and evolution of flammable hydrogen gas. Q SOS 1/2 1/1 8. WHAT SHOULD BE DONE TO EQUIPMENT CONTAINING RESIDUAL CAUSTIC PRIOR TO WELDING? Correct Metal surfaces must be cleaned/acidized prior to welding, cutting, or other OS SOS 2/2 1/1 forms of heat treatment. JGS 2/10/97 OS's scored 100% and 58% correct. SOS scored 100% correct. DO A 029747 CONFIDENTIAL