ML19317G906
| ML19317G906 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/08/1975 |
| From: | Davis E SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML19317G907 | List: |
| References | |
| NUDOCS 8004020563 | |
| Download: ML19317G906 (4) | |
Text
NRC DbiRIBUTION FOR PART 50 DOCKET.e.ATERI AL (TEMPORARY FORM) i CONTROL NO: 9Y)
FILE:
FFOM:
Sacramento Municipal Ut L10 ATE OF DOC DATE REC'D LTR TWX RPT OTHER Sacramento, Ca 7-8-75 7-14-75 XXXX E K Davis TO:
ORIG CC OTHER SENT NRC PDR XX Mr Giambusso 3 signed SENT LOCAL PDR XX CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:
XXXXXX 3
50-312 DESCRIPTION:
ENCLOSURES:
Ltr notarized 7-8-75.....trans the follow:
Andt to OL7 Change to Tech Specs #36:
consisting of revised ECCS analysis
....with supportive info.......
(40 cys encl rec'd)
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SACRAMENTO MUNICIPAL UTILITY DISTRICT O
6201 S Street. Box 15830. Sacramento. California 93813: (916) 452-39'i July 8, 1975 AA dWGN Mr. Angelo Giambusso, Director d'..~n% X. ' -
Division of Reactor Licensing
,,-U gl,; q U. S. Nuclear Regulatory Commission t.1 4
Washington, D. C.
20555 1
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s Re:
Docket No. 50-312 r~
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- -t proposed Amendment No. 36 Rancho Seco Nuclear Generating N
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Dear Mr. Giambusso:
p, N'/
Station, Unit No.1 N
r Pursuant to the Commission's Order for Modification of License for Rancho Seco Nuclear Generating Station, Unit I dated December 27, 1974, a re-evaluation of ECCS cooling performance calculated in accordance with an acceptable evaluation model which confoms with the provisions of 10CFR50, Section 50.46 has been completed and the Sacramento Municipal Utility District is submitting herewith proposed Amendment No. 36 to change Technical Specifications 3.1.7, 3.5.2.3, 3.5.2.4 and 3.5.2.5.
The prepared revisiens are indicated in the attached replacement pages (Attachment No.1).
The evaluation model utilized in perfoming the re-evaluation of ECCS cooling performance is described in Babcock & Wilcox (B&W) nonpro-prietary Topical Report BAW-10104, "B&W's ECCS Evaluation Model."
The results of the evaluation for B&W 177 fuel assembly units with a lowered-loop arrangement are described in nonproprietary Topical Report BAW-10103, "ECCS Evaluation of B&W's 177 Fuel Assembly Lowered Loop NSS."
The analysis presented in BAW-10103 for the B&W 177 fuel assembly units with a lowered-loop configuration is generic in nature and the parameters used in this analysis are conservative for Rancho Seco Nuclear Generating Station, Unit 1.
The parameters associated with Rancho Seco Nuclear Generating Station, Unit 1 are bounded by those utilized in the generic analysis, and thus BAW-10103 provides a conservative evaluation of ECCS perfomance for the Rancho Seco Nuclear Generating Station, Unit 1.
The results presented in BAW-10103 demonstrate the conformance of Rancho Seco Nuclear Generating Station, Unit 1 to the criteria of 10CFR50, Section 50.46 under the operating conditions specified in the attached proposed Technical Specification changes.
In addition to the above and in accordance with Mr. Robert A.
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's letter of June 13, 1975, the following information is also p f 043..,.
2 h 1.
Break Spectrum and partial-Loop Operation d
- s. _i '. M d-The analysis is made with the assumption that the LOCA 3/
maximum kw/ft. curve is applicable to partial pt m opera-
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Mr. Angelo Giambusso July 8, 1975 tion.
Confirmatory analysis is currently being completed and will be submitted by July 30, 1975.
2.
Potential Boron Precipitation The requested information was provided by Sacramento Muni-cipal Utility District in its letter of May 8,1975 in response to Mr. Purple's letter of March 14, 1975.
3.
Single Failure Analysis As requested, a single failure analysis for manually-con -
trolled ele trically-operated ECCS valves has been performed and is provided as Attachment No. 2 hereto.
Safety features actuated valves were considered previously in Table 6.2-5 of the FSAR.
Based on the information provided in Attach-ment No. 2, it is concluded that no credible single failure or operator error affecting any manually-controlled electri-cally-operated ECCS valve could significantly adversely affect ECCS performance.
Technical Specification 3.3.1 requires that the core flood tank discharge isolation valve operator breaker be locked open to prevent this valve from closing.
The next proposed change to the Technical Speci-fications will include locking open the breaker to the core flood tank vent valves to prevent them from opening and causing a loss of tank pressure.
4.
Submerged Valves A review of equipment arrangement to determine if any valve motors within the reactor building will become submerged following a LOCA has been performed and it has been con-cluded that there are no valve motors which would be flooded which are required to operate following a LOCA.
This con-sideration was incorporated into the piping layout for Rancho Seco Unit 1.
5.
Containment Pressure The containment pressure used to evaluate the performance capability of the ECCS has been calculated in accordance with the methods contained in Section 4.3.6.1 of BAW-10104 and the results are presented in Section 4.4 of BAW-10103.
Also, as requested on page 7 of the staff's Safety Evalua-tion Report which accompanied the.0rder for Modification of License, as-built passive containment heat sink data
.has been compiled and is given in Attachment No. 3.
The "as-built" values for all parameters in aggregate are 9
July 8,1975 Mr..Angelo Giambusso -
conservative. As noted in the margin column of Attachment 3, some values _ are non-conservative; however, the plus values more than compensate.
Specifically, the larger sur-face area of the dome is offset by the smaller surface area of the containment walls. Likewise, the larger area of internal stainless steel is compensated by the much smaller area of painted internal steel.
If an equivalent stainless steel heat sink area for the internal concrete were chosen by ratioing thermal conductivities by a factor of 10 to 1 for stainless steel and concrete, the heat sinks can be compared.
Internal concrete can then be assigned an equiva-lent area of about 6900 sq. ft. and it is then evident that the greater internal stainless steel and concrete is offset by the much smaller area of painted steel.
~A comparison was made of the paint thickness and conducti-vities.
The quotient of conductivity and as-built paint thickness compared to the quotient of the generic values is conservative; i.e., the heat conduction of the as-built paint is less than the generic model.
It is therefore, concluded that the heat sinks used in the B&W generic backpressure model for ECCS evaluation are more conservative (greater) than the as-built condition of Rancho Seco Unit No. 1.
Forty copies of this letter and attachments are enclosed.
Respectfully submitted, SACRAMENTO MUNICIPAL UTILITY DISTRICT Y
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By E. K. Davis General Manager
!e C/jVID S. - KAPLAN General Counsel or Sacrat,e aw Muni ipal Utility District g["""
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Subscribed and sworn to oefore me this g th day of July 1975
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O L.ILAs k IE W w #. 4/ etty Mattier) Notary Public in and
'p,fortheCountyofSacramento, State tf t
%g, of California My Commission Expires January 12, 1976