ML19290A096
| ML19290A096 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/07/1979 |
| From: | Thiesing J METROPOLITAN EDISON CO. |
| To: | Levenson M METROPOLITAN EDISON CO. |
| References | |
| TM-0953, TM-953, NUDOCS 7910010506 | |
| Download: ML19290A096 (2) | |
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TMI DOCUMENTS N"Of[)
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DOCUMENT NO:
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COPY MADE ON CF DOCUMSNI PROVIDED BT METROPOLITAN, EDISCN COMPANY.
Supervisor, Document Control, NRC 2221 123 7910010ST 6
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Milt Levenson DATE:
4/7/79 L
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SUBJECT:
Containment PROM:
J.W. Thiesin COPIES:
J.
Hurley 0F:
THI-IAG The following are some observations and estimates concerning the containment building and an estimate of the lower bound for total metal-water reaction.
I.
Operating History During Incident A.
Simulate H burn (1400, 3-28-79) to determine magnitude 2
of burn and confirm spray operation.
Determine pressure and temperature transient during H2 burn.
B.
More definitive containment pressure data is needed.'
Bas.ed
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on plot provided showing a 28 psig peak pressure,
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a burn of approx. 250 lb coles H7 would be required, equivalent to a 27% Zr-H O reaction consumed in the burn.
2 The burn would create a short term superheat in containment of (+1000 degrees F).
Spray actuation,would r. educe super-heat to zero in about 1 minute.
(operator log on 3-20-79 (1350) indicates that spray actuation occurred impIying a peak pressure of at least the 30 psig spray set point.
Contain-ment H2 at the time would have been 4.7% H2, assumming ali H was consumed.
2 II.
Current Status A.
Containment H is now at about 2 V/O corresponding to a 2
Zr-H O reaction of about 11.5%. (Thus metal water reaction 2
was greater than 27% + 11.5% = 38.5%).
- (Also note that a 1000 ft3 bubble in the RCS at 280 degrees F and 1000 psig would correspond to an additional 13% Zr-H O 2
reaction, and the saturated H O in RCS corresponds to,an 2
additional 2.5% Zr-H O reaction for a grand total estimate 2
o f 'a t least 54%
Zr-H O Reaction 2
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s Containment j/
Page Two
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8.
Curt'ent building pressure holding at about - 1.0 psig and 90 degrees F.
1.
Continued negative pressure probably implies some
.inward buckling of the liner pinte due to trapped air behind the liner and inleakage through flud head welds and hatch liners and seals to the area behind the liner plate.
Recommend maintenance of current status to prevent leakage of containment inventory to environment.
Any potential future liner problems could be solved-by allowing containment pressure to rise to - 0.1 psig but accuracy of containment pressure monitors and potential barometric pressure swings mitigate against this.
C.
Current containment leakage area, and rate of outleakage
,,as a function of positive pressure, could be estimated by careful simulation of current operating mode, and system and containment parameters.
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III. Future Disposition of ContLinment A.
Reduction of PCS temperature will increase ability,to
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maintain negative pressure in containment as will cessation of venting through pressurizer relief block valve.
B..
Increase in service water temperature as summer approgches will decrease ability to asintain negative pressure.
C.
Maintenance of negative pressure over a long period will increase containment non-condensible gas inventory due to inleakage, and thus reduce ability to maintain negative pressure.
Also, as the non-condensible gas inventory rises,.
the negative pressure inducing efficiency of the air coolers decreases due to the relative inefficiency of' reducing air temperature compared to reducing humidity by condensation.
D._ Should the reactor coolant system be forced into the feed and dump mode again, the containment can acconnodate the current heat load at a steady.-dtate temperature of about 200 degrees F (about 10-20 psig) forever with;'only one, air cooler running.
With all 5 coolers running, the steady-state
, temperature would be about 130 degrees F, maybe 1-3 psig.
(note:
steaming rate for current decay heat load is 40 gpa) h, Pressure rise with only one cooler running is very slow, re-sulting in a pressure o f 6. 5' p fig a t one day.
2221 125
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