40EP-9EO04 Steam Generator Tube Rupture (SGTR) Flashcards
What are the major Mitigating Strategy steps for 40EP-9EO04 Steam Generator Tube Rupture (SGTR)?
- Regain RCS inventory control and CTMTN isol.
- Cool RCS using BOTH SG’s to Th < 540°F (prevents lifting SG safeties)
- Identify and isolate affected SG
- De-pressurize RCS to < 1135 and ±50 psi of SG
- Maintain affected SG 45-80% NR
- C/D RCS with good SG
- Place SDC in svc
During a SGTR with LOOP and Stuck open ADV, how long do you have to cover affected SG tubes?
- 46 minutes TCA
- Use 2 AFW pumps
- scrubs Iodine, protects the public
What kind of detectors are the RU monitors for the main steam lines? 139/140, 142 a/b/c/d and what limitation is there associated with this type of detector
- N16 detectors
- Proportional to Rx power, lower initial power harder to detect
What is the accuracy of RU-139/140 Main steam line detectors (MSSS)
- 10-15 gpm
What is the accuracy of the main steam line detectors 142 a/b/c/d (Turb 140’)
- 30 gpd
What action is required if Main steam line RU monitors 139/140 (MSSS) or SGBD RU-4/5 alarm in HIGH
- Isolate Blowdown
How do you know if a SG leak is high or low in the tube bundle?
- High tube leak indicated in steam line RU’s
- Low tube leaks indicated in SGBD RU’s
For the Condenser PFB RU-141 a/b, what is the accuracy of each channel, which channel actuates PFB?
A - Actuates 1 gpm
B - Better 50 gpd
During a SGTR, what actions are taken to help reduce release to offsite prior to the cooldown?
- Ensure AR PFU in “Thru Filter Mode”
- SBCV’s 1007/8 to OFF
During a SGTR what is the initial cooldown target and why?
- Th < 540°F
- Prevents lifting SG MSSV’s when isolated
During a SGTR what is the preferred method of cooldown and alternate cooldown methods?
- SBCV’s 1001-1006
- ADV’s from CR
- SBCV’s 1007/8
- ADV’s locally
While depressurizing the RCS during a SGTR, if spray is not available or cannot maintain pressure in band, what else can be done to lower pressure?
- Use RCGVS
During a SGTR, how do you maintain the isolated SG < 1135 psia?
- RCS Cooldown
- MSIV bypass (monitored)
- ADV’s (unmonitored)
During a SGTR, what do you do if the wrong SG was isolated?
- Restore SG
- Then Isolate affected SG
- Maintain heat removal capability
What is HPSI Throttle Criteria?
- ≥ 24°F Subcooling
- > 10% Lpzr ↔ or ↑
- Un-isolated SG 45-60% NR with feed
- RVUH ≥ 16%
At what pressure would you stop the LPSI pumps and close their injection vlvs?
- Ppzr > 220 psia
- pressure is controlled
During a SGTR what are the RCS CDR’s?
< 100°F/hr with RCP’s
< 30°F/hr on Natural Circ.
- prevents loop from becoming stagnant due to asymmetric C/D
During a SGTR when and how often does Chemistry have to perform RCS Boron samples
- Prcs < Psg
- Every 30 Minutes
During a SGTR what must be done, in regards to RCP’s, what must be done if all RCP’s have been stopped?
- Disable RCP brkrs for isolated SG
- Prevents inadvertent dilution
During a SGTR what level do you maintain the isolated SG?
- 45 - 80% NR
During a SGTR how do you maintain the isolated SG level?
- Backflow to RCS (preferred)
- Drain to condenser (SGBD)
- Steaming thru MSIV bypass
- Increase RCS press to raise level
Which SG LT’s are less sensitive to temperature de-calibration?
- NR LT’s
During a SGTR, what must be done before restarting a RCP and why?
- RCS Sample
- Check for unborated water slug due to backflow
What parameters are used to verify Natural Circulation?
- Loop ▲T < 65°F
- Tc and Th ↔ or ↓
- ≥ 24°F Subcooled via CET
- < 30°F ▲T B/W Th and max quadrant CET
What is loop transit time while in Natural Circulation?
- 5-15 Minutes
During SGTR, what is required to use Backflow during SG C/D?
- RCP’s operating
- LD in svc
During a SGTR what methods are available to C/D and depressurize the SG?
- Backflow (preferred)
- Steam with SBCS
- Drain to condenser (feed & bleed)
- Ambient cooling
What are SDC Entry requirements?
- Lpzr > 30% and controlled
- ≥ 24°F RCS Subcooling
- Ppzr < 385 psia
- Th < 335°F
- RCS activity wont result in unacceptable doses outside CTNMT
