ML19224C142
| ML19224C142 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco, Crane |
| Issue date: | 05/02/1979 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 7906290132 | |
| Download: ML19224C142 (4) | |
Text
-
'~ b
' gg]
Y SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6:01 S Street. Box 12.T Sacramento. California 9913; GIS) 452-3211 May 2, 1979 Mr. R. H. Engelken, Director Region V Office of Inspection & Enforcement U. S. Nuclear Regulatory Cemmission 1990 North California Boulevard Valnut Creek Plaza, Suite 202 Valnut Creek, California 94596 Cocket No. 50-312 Rancho Seco Nuclear Generating Station, Unit No. 1
Dear Mr. Engelken:
The Sacramento Municipal Utility District has reviewed '
3ulletin No.79-05B dated April 21, 1979 This letter provides the Distrist responses to items 1, 2, 4 and 6 as requested by the Bulletin.
Item 3 was cc.;.gieted within the 24-hour requirement and reported to your office on April 22, 1979 Item i Develop procedures and train operation personnel on Eethods of establishing and maintaining natural circulation.
The procedures and training must include means of moni toring heat removal efficiency by available plant instrumentation.
The procedures must also contain a method of assuring that the primary coolant system is subcooled by at least 50 F before natural circulation is iniciated.
In the event that these instructions incorporate anticipatory filling of the OTSG prior to securing the reactor coolant pumps, a detailed analysis should ce done to provide guidance as to the expected system response. The instructions should include the following precautions:
a.
maintain pressurizer level sufficient to prevent loss of level indication In the pr-ssurizer; b.
assure av6ilabi i.y of adequate capacity of pressurizer heaters, for pressure control and maintain primary system pressure to satisfy the subcooling criterien for natural circulation, and c.
maintain pressure - temperature envelope within Appendix G limits for vessel integrity.
Procedures and training shall also be provided to maintain core cooling in the event both main feedwater and auxiliary feedwater are lost while in the natural circulation core cooling mode.
So-sm q
-256 165
"*N s o-AN E LECT Ric SYsit u S E Ryt N G MORE THAN G 0 0,0 0 0 IN THE Jt E A ft i 0F C A LI F 0 R N I A
e Mr. R. H. Engelken Page 2 May 2, 1979 Reolv to item I Shutdown and Cooldown, " section 6, " Natural Circulation Procedure B.4, " Plant Cooldown," is being revised to contain methods of establishing and maintaining natural circulation. This procedure will include means of monitoring heat removal efficiency by utilizing available plant i n s t rumer.t a t i o n.
The procedure will also contain a method of assuring that the primary coolant system is subcooled by at least 50 F before natural circulation is initiated.
This procedure will be completed and the required training performed prior to Rancho Seco's proceeding above cold shutdown.
Presently we do not expect that anticipatery filling of the OTSG will be Babcock and Wilcox is required prior to securing the reactor coolant pumps.
If there is any change so that the reviewing this area at an accelerated pace.
need for anticipatory filling is necessary, Region V will be notified and schedule for the impelementation within the operating procedures will be supplied.
the Procedure B.4, " Plant Shutdown and Cooldown," has been modifed to instruct operato. s in the proper response in the case where both main feedwater and lost while in the natural circulation core cooling mode.
auxiliary feedwater are This pc acedure and the necessary training will be approved and completed prior to Rancho Seco's proceeding above cold shutdown.
Item 2 Modify the actions required in item 4a and 4b of IE Bulletin 79-05A to cake into account vessel integrity considerations.
"4.
Review the action directed by the operating procedures and training instructions to ensure that:
Operators do not override automatic actions of engineered safety a.
features features, unless continued coeration of engineered safety will result in unsafe olant conditions.
For exacole, if continued operation of encineered safety features woulo threaten reactor vessel intecrity then the HPl should be secured (as noted in b(2) below).
if the Operating procedures currently, or are revised to, speci fy that L.
high pressure injection (HPI) system has been automatical'y actuated because of low pressure condition, it must remain in operation until either:
Both low pressure Injection (LPI) pumps are in operation and (1) flowing at a rate in excess of 1000 gpm each and the situation has been stable for 20 minutes, or (2) The HPl system has been in operati,n "or 20 minutes, and all hot and cold leg temperatures are at least 50 degrees below the If 50 saturation temoerature for the existing RCS pressure.
cutoff, the degrees subcooling cannot be maintained after HPl HPl shall be reactivated.
The decree of subcoolina beyond 50_
decrees F and the length of time HPI is in aeration shall be
- limi ted by the oressure/temocrature considerations for the vessel intecrity."
,i
4 Mr. R. H.
Engelken Page 3 May 2, 1979
~
Reolv to item 2 The Rancho Seco procedures have been modi fied to comply with all these conditions.
If the ves.sel integrity is not threatened, then HPl will be operated for at least 20 minutes and until the hot and cold leg temperatures are at least 50 F below saturation temperature for the existing RCS pressure.
If the vessel integrity is threatened, that is, if the reactor coolant system pressure / temperature relation-ship is outside of the allowable curves shown in the Technical Speci fication Figures 3.1.2-1 and 3.1.2-2, then the high pressure injection pumps will be secured even though they have run for less than 20 minutes or there is less than 500F subcooling below the saturation temperature for the existing RCS Once the reactor coolant system pressure / temperature relationships pressure.
are again within the allowable curves as stated above, the HPI system will be restarted in order to obtain the 50 F subcooling.
Item 4 Provide procedures and training to operating personnel for a prompt manual trip of the reactor for transients that resul* in a pressure increase in the reactor coolant system.
These transients i.
..ae:
a.
Loss of main feedwater b.
Turbine trip Main Steam isolation Valve closure c.
d.
Low OTSG level f.
Low pressurizer level.
Reciv to item 4 The following procedures have been modified to require prompt manual t-ip of the reactor, Operating Procedure 0.14, Revision 5, " Loss of Steam Generator Feed," has a.
been changed to require a manval reactor trip on loss of feedwater to the OTSG's.
b.
Operating Procedure 0.14, Revision 5, " Loss of Steam Generator Feed," and 0.2, Revision 2, " Turbine Trip," hm/e been changed to require a manual reactor trip during a turbine trip.
Rancho Seco does not employ main steam isolation valves but verification of c.
the automatic action of closure of the turbine throttle and governor valve c!csure is performed in Operating Procedure D.2, Revision 2, " Turbine Trip."
256 167
,i
4
~
Mr. R. H. Engelken Page 4 May 2, 1979 d.
Operating Procedure 0.I, Revision 3, " Load Rejection," has been changed
.to require a manual reactor trip on loss of offsite power with loss of reactor coolant flow.
Operating Procedure 0.14, Revision 5. " Loss of Steam Generator Feed," has e.
been changed to require a manual reactor trip on low OTSG 1evel.
f.
Operating Procedure 0.5, Revision 9, " Loss of Reactor Coolant / Reactor Coolant Pressure," and 0.11, Revision 2, "Lc 4 of Reactor Coolant Makeup / Letdown,"
have been changed to require a mansal reactor trip on low pressuri:er level.
Training will be completed fr all operating personnel for the above procedures prior to Rancho Seco's p. act. ding above cold shutdown.
Item 6 The actions requ red in item 12 of IE Palletin 79-05A are modified as follows:
i Review yctr prom t reporting precedures for NRC notification to issure that NRC is notified within one hour of the time the reactor is not in a L^ trolled or excected conditicn of coeraticn.
Further. a,t that time. an coen continuous communication channel shall be eslablished and maintained weth NRC.
Reciv to iten 6 A Standing Order eill be issued to 9 8I operating personnel that the NRC shall be notified within one hour from tts time the reactor-is not in a controlled or exoected condi tion of opec 4 tion.
The District has defined "the NRC" as Revion V located in Walnut Creek.
The Distri;t has defined "the reactor is not in a cent rolled or expected condition of operation" as a change in electrical genera-ter output of more than 50 MWe whicF is not scheduled.
If the reactor is shut dcwn, the NRC will be notified within one hour if unplanned cessation of reactor coolant flow occurs. An open communications channel is defined as a speaker phone located in the Control Room area which will allow the Region V personnel the capability of listening to activities occurring within the Control Room.
This open communications chancel shall remain open for each notification until the Region V personnel agree that it is no longer required.
This requirement will be completed prior to proceeding above cold shutdown.
Respectfully submitted, 0.
. h 6h J. Mattimoe Assistant General Managar and Chief Engineer JJM:RWC: Jim cs:
Of fice of Inspection and Enforcement Division of Reactor Operations inspection Washington, D. C.
2c555 256 168
,