ML19241B315
| ML19241B315 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 04/20/1979 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| FOIA-79-98 NUDOCS 7907160059 | |
| Download: ML19241B315 (4) | |
Text
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TECO'S RESPONSE TO IES 79-05 & SITPPLEMENTS u....
(DAVIS-BESSE 1)
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..._.7 Item 1, Concem 1, and Item 2 Based upon the licenscc response, it is not possible to determine whether he covered the spectrum of events that :ould cause excessive cool down of the RCS and possible voiding of the prassurizer.
The infor=stion submitted g-address only transients associated with feedwater (i.e., he appears ter doesn't say that he has looked at other cruoulents and has not identified other pynblems.)
One concern would bc ICS induced transienta.
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Item 1, Concern 1 and item 5 Information:
R11I is presently preparing a memo to IE:HQ requesting a f
re-evaluation of DD valve position indication.
It appearn that DB-1 f - ""
does not mcat the criterion of redundant diverse valve position indication b
required by IEEE 279 and Reg. Guida 1.49.
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D Ttem 1, Concern 1 u
"kE h 1icensee response addresses what action will be taken co prevent lor:s of auxillary feedvater.
The response does not address what action uhnold be taken if auxiliary fced ix lost or delayed, i.e., should there be special precautions for feeding a dry steam generate r to prevent excessive E
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cool down and depressurization?
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Item 1, Concern 1 c:
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Info rma t ion :
Per License Condition C(3)(f), the licensee has committed b
to install DC valve operatorn on one train of auxiliary feedwater durir.d I
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the first refueling outage.
Tu increase the ra11 ability of the auxiliary s
feedwate r, the liennsee attc=pted to procure the necesuary equipment to completc the installation during this preucut maintenanca outzge.
T'ie DC motor starter delivered will not fit the panels and cannor be modified and still mu
- the seismic acceptance criteria.
RIII f6elu that NRR should revie, condition C(3)(f) of the 11canoa to deternine whether installat. ion by the first refueling outage (3/80) is still acceptable.
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Item 1 Pr.ncern 2 The statement in the response that failurq of the c? octroraatic relief does
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not comprocise the plant cat be misleading.
Fa1.lurc of the relief valve to close would probably cause the Quanch Ta k ruptute diac to rupturc.
This rupturc in itself could compro=1so aafocy depending upon its effects on instrumentation (such as pressure sens*.o.g linea), cabling, p
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ventilation ducting, and RCP's. i.e., relative poultion location of this
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equipment with respect to the Quench Tank.
Davis-Besse 1 had such an event in which SC level indica-ion was af fected, SG insulation was blevn off, ventilation ducting vas damaged and non-essential pressurizer henter cabica
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were wetted.
DB-1 did innta11 a deflector to direct the diochar.ge away from this equipment, thereby correcting thie potential problem *, however.
this matter should he evaluated at other plants.
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Information:
Although operators are and will be trained to ic ck for a 6-.
failed open pressurizar electromatic relief valve, it is not an easy task.
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The status of the valve is not directly monitored (design of valve does not lend itself r.o direct position monitoring).
Status monitoring at Davis-Bessa 1 includes:
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k*hether there is a signal to the solenoid on the pilot valve.
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The position of actuating stem on the pilot valve.
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Of scharge temperat are monitor.
This is only effective to tell you that the valve was opened because af the slow cool down rate.
Based upon DB-1 experience, the pilot valve is the weak point in thu equipment and any buildup of boric acid on the stem can cause the valve to stick open.
The valve has functioned properly since a modificatiou to the
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stam of the pilot valve made 10/77.
Item 1, Cancern 3 The licennee respense does not addresa any long term fix on pressurizer level indications to eliminate such things as off gassing or flashing in the reference legs that can lead to falee level indications.
Item 1, Concern 6 and Icem 2 The licensee response addrennes the need to leave the RCP's on, but does
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nul address any guidance that vill be given the operators as to when he g.
may have to shut down the RCP's to prevent damage to RCS integrity.
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Itum 3.c
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The licennue's responvu addresses what is being done to prevent or
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minimize the formation of volds.
It does not addrers ubut should be 22' donc if voids are preacnt or how they would handle noncondensable voids.
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Item 4.d M 5-The responr.a does not really address how an operator will. use temperature and pressure to determine RCS water inventory or whether there will be a long term tix to provide this information.
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The licensec's response addresses automatic isolation of contalu=ent but does not cover specific control over nor= ally closed manual isolation E
valves or blank flanges (i.e., refueling tubes).
Item 7 and Item 5 More information will be needed as to which valvoo vill be controlled
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via the key lock.
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Item 8 E
Clarification: How and when will these requirements be reflected in the c-ch Spec:s.
Item 9 The licensee's response did not address level 5 actuation of SFAS in which there is an automatic transfer to the containment amargency sump on low BWST level.
In view of the TMI incident, it may not necessarily be a good idea to have this automatic function.
The licensee should
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address this.
Item 9
.The licenseu response did not address the automatic actuation of the i
Emergency Ventilation System (EVS) on a level 1 SFAS.
The EVS pumps down portions of the Auxiliary Building and the annulus between containnent F:
and shield building and exhausts it to atmosphere throug5 absolute and c::
charcoal fi?tcrs.
In view of the THI incident, this can be an undesirable releasc path of Xe and Kr to the atmosphure and may require operator action.
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Item 9 Although not required by the. bulletin, there are several potentially weak points in radioactivity fluid flow paths in the Auxiliary Building d
should high radioactivity fluid be inadvertently pturp.ed out of containment, i.e., rupture discs in the Reactor Drain Tank and the Degassifier.
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There necds to be more spccific commitments when changes will be completed.
We need dates to dt.cermine if they are acceptable to NRC.
Status RIII has not reviewed any of the procedure changes made to date.
Our i
current agreenent with the liccusee is that we will rcccive a copy of r'.-"'
the draft changes when they are submitted to the Station Superintendent for his review.
Items 1 and 2
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RIII knows that the liceuvee has reviewed more transients than indicared in the response, but doas at know the full extant nor have we seen p
the conclusions drawn.
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R1II knows from pravious revicus that automatte containment isolation is IU as licenscc states. However, RIII will re-review testing of these systems
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to verify that they work as designed.
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The plant is in cold shut down and is not scheduled to start up until about 4/20-21/79.
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