ML20039B562
| ML20039B562 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/16/1981 |
| From: | Wisenburg M TENNESSEE VALLEY AUTHORITY |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| TASK-2.K.3.15, TASK-TM NUDOCS 8112230238 | |
| Download: ML20039B562 (2) | |
Text
. -, _ ---
... -. - -. ~..
.x i
e.
TENNESSEE VALLEY AUTHORITY-CH ATTANOOG A. TENNESSEE 374o1 400 Chestnut Street Tower II
?
December 16, 1981 1
Director of Licensing Attention:
Mr. Thomas A. Ippolito, Chief 4
Operating Reactors Branch No. 2 U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Ippolito:
In the Matter of the
)
Docket No. 50-259 i
Tennessee Valley Authority
)
50-260 j
50-296 4
Your letter to H. G. Parris dated October 13, 1981 requested that TVA provide additional information regarding our response to NUREG-0737 Item II.K.3 15 which involves modifying the High Pressure Coolant Injection (HPCI) and Reactor Cora Isolation Cooling (RCIC)
Systems for Browns Ferry Nuclear Plant. -We have reviewed this i
request for information and our responses to the items of concern are enclosed.
9 4
]
Very truly yours,
- 6 773CE 3 S
/
TENNESSEE VALLEY AUTHORITY,9 J
DEC225p!
g.
[C\\crt5E6 s
n
(
1 Y
M
\\
4 i
M. R.
senburg
\\
\\-
L"O' jQ-N Nuclea Engineer
\\
A Subscribed a d sworn to before N
+
, me this /[o day of o()9A24tled 1981'.
'x f
)
t Notary Public MyComm!scionExpires9~h-3 Encloeure O
5 j
Ii 1
8112230238 811256 PDR ADOCK 05000259 P
.PDR An Equat Opportunity Employer
.. ~...
=
o ENCLOSURE REQUEST FOR ADDITIONLL INFORMATION NUREG-0737 ITEM II.K.3 15 BROWNS FERRY NUCLEAR PLANT (50-259, -260, -296)
T. A. Ippolito's letter to H. G. Parris dated October 13, 1981 requested additional information regarding TVA's responses to the subject NUREG-0737 item. Our responses to the three specific concerns addressed in this letter follow.
The first concern is whether the modification will serve the intended function of preventing spurious isolations. This modification has been in place on the HPCI system for several years. Surveillance testing which includes a simulated initiation quick start, with a flow path open to the condensate system to load the turbine during startup, is performed each month. Numerous actual initiations of HPCI have also taken place during abnormal transients. During this operating experience, spurious HPCI isolation due to the break detection logic has not been a problem.
This modification has not yet been made to the RCIC system due to lack of materials and is currently scheduled to be performed during the next refueling outage for each unit starting with the current unit 3 refueling outage. Since spurious isolation has not been a problem in the past for RCIC without a time delay relay, it should be even better protected when the modification is completed.
The second concern is whether the time delay in the isolation circuit will increase the consequences of an HPCI or RCIC steam line break. A safety analysis was performed for the HPCI system before installation of the three-second time delay. For the purpose of limiting inventory loss from the reactor, the HPCI steam line contains a flow limiting orifice which limits the break flow to three times the normal HPCI steam flow.
4 This amount of steam flow for an additional three seconds does not constitute a significant loss of inventory. For the purpose of environmental qualification, the HPCI and RCIC steam line isolation logic is assumed in the analysis to include an isolation delay which is clearly conservative. The RCIC steam line break is assumed to be bounded by the HPCI steam line break analysis since the RCIC has a much smaller steam line.
The third concern is that technical specifications hava not been proposed to deal with this new time delay rC9 > as required by NUREG-0737.
Technical specifications requiring calibration and surveillance of the i
time delay relay will be submitted for the HPCI system before beginning the next operating cycle on each unit (TS table 4.2.B - note 6). A similar requirement will be proposed for the RCIC system before the implementation of the modification.
Io e
e---
e-