ML18025B894
| ML18025B894 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/17/1982 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML18025B893 | List: |
| References | |
| NUDOCS 8211230316 | |
| Download: ML18025B894 (5) | |
Text
ENCLOSURE 1
PROPOSED TECHNICAL SPECIFICATION REVISION TVA BFNP TS 179 SUPPLEMENT 1
BROWNS FERRY NUCLEAR PLANT UNIT 2 7 8211230316 821117 PDR ADOCK 0500028&'
r
h VV
~ I s
e LIHITING CONDITIONS FOR OPERATION SURVEILLANCE RFQUIREt'ANTS F 3
!ted cttvttv Contro!
C.
If Specificst!ons
- 3. 3.. snd
. D
~bove csnnot be nlet
. sn ozdst ly shucdovn shsll be !a!t!sttd snd che reactor shsil be In the shutdown conditLon vfthin 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
C ~ 3 ttcse.t! v~tt Cnsvt tO!
E.
Surveillancr requirements are as specified in 4.3.C and
.D, above.
F.
F.
Seeem Illselme~e Volume (gDV)
- 1. The scram discharge volume drain and vent valves shall be operable any time that the reactor protection system is required to be operable except as specified in 3.3.F.2.
- 2. In the event any SDV drain or vent valve becomes inoperable, reactor operatio may continue provided the redundant drain or vent valve is operable.
- 3. If redundant drain or vent valves become inoperable, the reactor shall be in hot standby within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
I.a.
b.
2.
The sctam discharge volume drain and vent valves shall be verified open prior to each startup and monthly thereafter.
The valves may be closed intermittently foz testing not to exceed I hour in any 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period during operation.
The scram discharge volume drain and vent valves shall be demonstrated operable monthly.
When it is determined that any SDV drain or vent valve is inoperable, the redundant drain or vent valve shall be demonstrated operable immediately and weekly thereafter.
3.
No additional surveillance required.
126
ENCLOSURE 2
Descri tion and Justification, During the unit 2 reload 4 outage, the scram discharge volumes (SDVs) and scram discharge instrument volumes (SDIVs) are being modified to address
'inadequacies identified by the partial rod insertion event on Browns Ferry Nuclear Plant unit 3 in June 1980.
One of the modifications includes adding another valve in series to the existing drain and vent valves on the SDV and SDIV.
Another modification includes adding diverse differential pressure (dP) switches and installing more reliable float switches to initiate a scram on a high level in the SDIV.
As des1gned, the drain and vent valves serve two purposes neither of which is a direct safety function.
The first purpose, when the valves are in the open position, is to provide a positive means of maintaining the SDV drained to ensure adequate volume to accept water discharged during a scram.
The direct safety function of adequate volume is ensured,
- however, by the redundant and diverse SDIV level instruments described above.
The second
- purpose, when the valves are in the closed position, is to limit the amount of water discharged to the radioactive waste system following a scram.
There is no direct safety funotion associated with this purpose, but two othe>
means are designed to alleviate this operational inconvenience.
The first is the control rod drive (CRD) seal design which serves as the reactor pressure boundary to limit leakage.
The second is the proven ability to reset the scram under most conditions in less than five minutes thereby closing the scram outlet valves and stopping flow to the SDV.
Implementation of the SDV and SDIY modi.fications adding the redundant vent and drain valves provides increased assurance that the second purpose will be fulfilled while decreasing the probability of fulfillment of the -first purpose.
Given the high level of confidence of the level switches meeting the first purpose versus the somewhat lower confidence of being able to reset the scram and fulfillingthe second purpose, it is prudent to specify and maintain a certain level of operability to meet the second purpose.
In the case of the drain and vent valves not serving a direct safety function, one of a redundant pair of valves is fully adequate for continued power operation with increased surveillanoe of the operable valve.
I~~