ML19317G888
| ML19317G888 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/13/1978 |
| From: | Reid R Office of Nuclear Reactor Regulation |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| TAC-6710, NUDOCS 8004020547 | |
| Download: ML19317G888 (4) | |
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DISTRIBUTION.
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- rr itarch 13, 1978
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Docket flo. 50-312 KRGoller/TCarter FI ~
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Sacramento Municipal Utility District 01&E(3) p......
ATTN: !!r. J. J. !!attimoe DEisenhut f==E Assistant General l'.anager TAbernathy p
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6201 S Street ACRS(16)
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P. O. Box 15830 file E=Ei{
Sacramento, California 95813
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Gentlemen:
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By letter dated October 14, 1976, as clarified by your letter of
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October 8,1976, you proposed certain plant and procedural modifi-cations for Rancho Seco fluclear Station Unit lio.1 (RS-1) to provide F.;;'.
additional protection against overpressurization of the reactor-coolant system uith respect to 10 CFR 50, Appendix G limits. These modifications
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consisted of addition of a dual setpoint feature to the pressurizer E~
power-operated relief valve (p0RV), and procedure changes to effect E;= ; -
isolation of certain valves to minimize the possibility of high pressure P
safety injection under conditions when such pressures could violate gg Appendix G limits.
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Your letter of !! arch 17, 1977 presented an analysis of the susceptibility
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of the RS-1 reactor coolant system to overpressurization events and
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surplied additional information requested by the staff concerning Er i your proposed modifications.
In response to our letter of flovember 2,1977
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requesting more detailed information concerning the proposed modifications, E=
your letter of December 22, 1977 stated that the design effort had E===
not yet proceeded to the point where such detailed information could
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be supplied. The December 22, 1977 letter also stated that the design
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effort had been held in abeyance pending NRC approval of the proposed design change. This letter further cotmitted, however, to provide the requested additional information by February 28, 1978.*
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- Subsequent to this cornitment, you requested an extension of this 75 i
==8 date to not later than flarch 30, 1973. 'As indicated to you by y L;-
9==t lir G. Zwetzig, of our staff in a telecon on February 28, 1978, L
this date is acceptable, but your submittal should be made earlier b
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if possible.
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At the request of the staff, you submitted details of the proposed
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dual setpoint PORY modification in advance of your formal submittal.
This information was transmitted by facsimile on February 18, and 21,1978, and discussed with Mr. Robert Daniels of your staff, on February 24, 1978.
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This is to advise you that on the basis of our review of your earlier
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submittals and our preliminary review of your February 18 and 21,1978
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submittals, we conclude that the proposed design for the dual setpoint
..m.m power operated relief valve portion of the design is acceptable for
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m installation at this time on an interim basis pending completion of
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our review.
If completion of our review indicates that modification of this portion of the design is needed, you will be so advised.
'It is noted that while the incorporation of the dual setpoint PORV feature into your spstem provides substantial improvement in'the
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r,ostulated initiating mechanisms, it does not provide the needed
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level of protection against inadvertent hich pressure safety infection as discussed in our letter of November 2,1977. The submittal you
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have committed to transmit no later than March 30, 1978 should fully address this concern.
With respect to the installation of the dual setpoint PORV feature, you have indicated in telephone conversations with the staff that installation could be completed within about four weeks of receipt of this letter.
In view of the fact that in October,1976 you coaaitted to install this feature prior to January 1,1977 and in
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view of the protracted delay that has occurred since that comitment, and because of the importance of this feature to safety, we consider
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its installation within the above schedule to be an urgent natter.
If there is any further delay relative to the above schedule, we should be
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notified within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, with an explanation and complete justification
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for the delay.
Sincerely,
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Robert U. Reid, Chief Operating Reactors Branch f4 Division of Operating Reactors
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...N At the request of the staff, you submitted details of the proposed dual setpoint PORV modificatior, in advanc.e of your formal submittal.
This infomation was transmitted by facsimile on February 18 and 21,1978, T ~
and discussed with Mr. Robert Daniels of your staff, on February 24, 1978.
jEr C.R This is to advise you that on the basis of our review of your earlier k....
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submittals and our preliminary review of your February 18 and 21,1978 i:
submittals, we conclude that the proposed design for the dual setpoint i
power operated relief valve portion of the design is acceptable for
!;7 installation at this time on an interim basis pending completion of our review.
If completion of our revieu indicates that modification of this portion of the design is needed, you will be so advised.
It is noted that while the incorporation of the dual setpoint FORY
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feature into your system provides substantiat icprovement in the ability to mitipate overpressurization events caused by a number of
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postulated initiating mechanisms, it does not provide the needed level of protection against inadvertent high pressure safety injection
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as discussed in our letter of November 2,1977. The submittal you have committed to transmit no later than March 30, 1978 should fully
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address this concern.
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=W With respect to the installation of the dual setpoint PORV feature, you have indicated in telephone conversations with the staff that installation could be completed within about four weeks of receipt of this letter. You are requested to promptly advise us if there
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is any delay in meeting this schedule.
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Sincerely,
+f sjii Robert H. Reid, Chief N==
Operating Reactors Branch f4
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Division of Operating Reactors cc:
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. Sacramento;ttunicipal Utility District 1;
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cc: David S. Kaplan, Secretary and
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' General: Counsel
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6201 S Street.
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Post Office Box 15830' Sacramento, California-95813
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. Business and flunicipal Department-828 I Street
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Sacramento -City-County Library Sacramento,' California - 95814
.?42 255
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