ML19317G896
| ML19317G896 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 11/02/1977 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| TAC-6710, NUDOCS 8004020554 | |
| Download: ML19317G896 (4) | |
Text
__
t flovember 2,1977 DISTR"30TI0ft:
s Docket No. 50-312 L PDR ORB #4 Reading VStello KRGoller RWReid Sacramento Municipal Utility District L01shan i
ATTN: Mr. J. J. Mattimoe RIngram Assistant General Manager OELD and Chief Engineer 01&E(3) r 6201 S Street DEisenhut P. O. Box 15830 TBAbernathy Sacramento, California 95813 an Gentlemen:
file l
The flRC staff has completed a preliminary review of the over-pressure protection system for Rancho Seco. We have found that the system currently installed in combination with the proposed changes does not neet all the criteria established by the flRC.
E n
a Your proposed system maintains a gas blanket or bubble in the
~
]
pressurizer at all times, in conjunction with a single low pressure 1
setpoint relief valve.
~..M s design has certain advantages over
~
other concepts because failure of an operator to manually enable the low pressure setpoint of the relief vr.1ve does not totally defeat protection against a pressure transient. The staff has concluded that your proposed system adequately accommodates all
?
postulated overpressure transients with the exception of an J
inadvertent initiation of safety injection by the high pressure injection (HPI) pump.
.n Based on your analyses we have identified !!PI as the limiting mass addition overpressure transient. Operation of the HPI pump, which is capable 6f delivering flow against full system operating pressure, is required whenever a reactor coolant pump is in operation. Since the discharge of the HPI pump is isolated from the reactor coolant system by a single injection valvo, a sinole error or equipment failure could oper the injection valve and initiate a pressure increase in the primary system.
If failure of the single low setpoint power i
operated relief valve is then assumed ic; the single failure following initiation of the event, your analysis iaows that operator action is required within five minutes to mainuin primary system pressure below Appendix G limits. This is not ir accordance with FIRC criteria J
j for operator action w5ich prohibits the assumation of operator inter-
, : ?..
vention for ten minutes, and which requires the assumption of a single M
8004020 N T
~
R failure following the initial failure or error which is postulated to cause the transient. Since your pmposed system does not fully satisfy our established criteria we require that you propose system modifications that will provide overpressure pmtection in full confomance with NRC criteria, and that you provide a schedule and a value-impact assessment to make all necessary hardware changes.
It is also the NRC position that to assure proper alighment of the overpressure protection system during plant cooldown, an enabling alarm must be pmvided which monitors the system enabling switch and the position of the isolation vatve upstream of the PORV.
j l['
Your previous submittels do not provide detailed electrical circuit F
and logic diagrams of the overpressure protection system to facilitate a thorough review.
Please provide the following:
1.
RCS overpressure protection system diagram; l
2.
Logic Diagram; 3.
Contml Circuitry Diagram; 4.
Instrument loop Diagram; t
5.
Annunciator System Schematic; and 6.
Overpressure Protection Control Display and layout.
In addition to the items discussed above, the staff has identified several concerns related to power operated relief valve (PORV)
If maintenance and HPI testing for the currently proposed system.
the relief valve requires maintenance the upstream isolation valve j
would need to be closed thereby removing the singic relief salve Therefore the staff will require Technical Specifica-fron service.
tions which stipulate that when the reactor vessel temperature is below the minimum value for which the vessel can be fully pressurized the PORV may be removed from service for a hbert period of time only (1) charging pumps are out of service and all HPI injection if:
valves are closed and power renoved, or (3) the vessel head is removed.
Regarding HPI testing, the staff will require that your procedures state that the HPI valve be allowed to be cycled only if all HPI pumps are out of service, or vessel temperature is above the mindmum value for which the vessel can be fully pressurized, or the reactor vessel head is removed.
i'
s
% p We will require that your Technical Specifications identify the system enabling temperature and the PORY eetpoint.
In addition, you should propose specifications related to system testing.
1 These maintenance and testing restrictions should be examined to r'
assure compatibility with present Technical Specification require-ments regarding the operability and periodic testing of ECC and emergency boration syste$s. Also, since the inpact of the proposed l
Technical Specifications will be considered by the sta#T in determining the acceptability of the proposed overpressure mitigating system, you should provido a thorough evaluation of the i
effect of these maintenance and testing requirements on the susceptibility of the reactor coolant system to a pressure transient.
You should provide the above requested information and the proposed 4
Technical Specifications within 45 days of receipt of this letter.
Sincerely, i
Robert W. Reid, Chief Operating Reacters Branch f4 Division of Operating Reactors I.
cc:
See next paga h
(
I o.. c s, f Cg*{:00R 0RB#4:00R M 01shan:dn RWReid 11/ 2 /77 11/?-/77
..7..~...
,.;;4
??I:::.D:.
= = = -
7:.
' 'i Sacramento Mtt i:ipal Utility District it....
L i
(.+
cc: David S. Kaplan, Secretary and
- l{ ;g;g.3 General Counsel
- s=
-6201 S' Street s
Post Office Box 15830
==G:
E Sacramento, California 95813 Business and Municipai Department
=
Sacramento City-County Library
- 2=
828 1-Street
~~
Sacramento, California 95814 e
f/
4
- a::.
'::.v:
i l
p
- 9 e
l
=w.
I e
4
' g w q a
w r
4 4
r w-w w-,r m.-
n--.