ML19322C608
| ML19322C608 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco, Crane |
| Issue date: | 09/11/1973 |
| From: | Mangelsdorf H Advisory Committee on Reactor Safeguards |
| To: | Ray D US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML19322C601 | List: |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8001170926 | |
| Download: ML19322C608 (5) | |
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ADVISORY COMMITTEE ON REACTOR SAFEGUARDS UNITED STATES ATOMIC ENERGY COMMISSION WASHINGTON. D.C.
20545
't September 11,.1973 Honorable Dixy Lee Ray Chairman U. S. Atomic Energy Commission Washington, D. C. 20545
Subject:
REPORT ON RANCHO SECO NUCLEAR CENERATING STATION, UNIT 1
Dear Dr. Ray:
During its 161st mpeting, September 6'-8, 1973, the Advisory Committee on Reactor Safeguards reviewed tha application of the Sacramento Municipal Utility Distrist for a license to operate the Rancho Seco Nuclear Gener-ating Station, Unit 1, at power 1cvels up to 2772 MW(t). This project had been considered previously during the 159th meeting of the ACRS, July 12-14, 1973, by Subcommittee meetings in Sacramento, California, on June 13 and 14,1973, subsequent to a tour of the site, and in s
Washington, D.
C.,
on August 22, 1973.
In the course of its review, the Committee had the benefit of discussions with representatives and consultants of the Sacramento Municipal Utility District, the Babcock and Wilcox Company, the Bechtel Corporation, and the AEC Regulatory Staff, and of the documents listed. The Committee last reported to the Commission on the construction of this plant in its letter of July 19, 1968.
The Rancho Seco Nuclear Generating Station is located about 25 miles southeast of Sacramento, California. Water for this plant will be supplied from the Folsom South Canal. An on-site reservoir will have a capacity of 2500 acre-feet, and two spray ponds can provide cooling water for decay heat removal for about 30 days.
The Rancho Seco nuclear steam supply system employs a Babcock and Wilcox two-loop, press'rized water reactor essentially identical in design to u
the Oconee Nuclear Station Unit No. 1, previously reported on by the Committee.
However, Rancho Seco will operate at approximately 87. higher power level and will use control of boron concentration in the core cool-
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ing water to aid in reactivity control during power maneuvering.
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. Honorable Dixy Lee Ray September 11, 1973 The application for a construction permit proposed initial operation at power icvels up to 2452 W(t), the same as the construction permit power icvel of the Oconee Nucicar Station, Unit I which employs a similar reactor. The safety analyses have been completed assuming a power of 2568 W(t). The application for an operating license proposed power levels up to 2772 N(t) and safety studies have been made at this power.
This increase in power is accomplished by utilizing larger primary cool-ant pumps and by increasing the average coolant temperature rise in the core. The Committee believes that review of the operation of Oconce Nuc1 car Station, Unit 1 by the Regulatory Staff should be completed and satisfactory performance of Oconce Nuclear Station, Unit 1 should be demonstrated before Rancho Seco Unit 1 is operated at full power. In addition, the Committee agrees with the Regulatory Staff that it would be prudent for Rancho Seco Unit 1 to operate at power levels up to 2568 W(t) for an appropriate time period and for the Staff and the ACRS to review this experience prior to allowing operation at full poacr of 2772 W(t).
Independent confirmation by the Regulatory Staff of the applicant's analpses of linear heat generation rates, operating limits, and ECCS cfficacy, and submittal of a supplemental Staff Safety Evalua-tion Report should precede this review for operation at full power.
Fuel for the reactor has been thermally resintered wc's the purpose
'of reducing fuel densification under irradiation; furthermore, the fuel assemblies are being classified acecrding to their maximum allowable linear heat rate and are to be loaded into the reactor according to this classification. This matter should be resolved in a manner satisfactory to the Regulatory Staff. The Committee wishes to be kept informed.
The applicant has stated that, under normal conditions, reactor produced radioactive liquid wastes will not be released to the enviconcent. This will be accomplished primarily through processing and reuse of liquids renoved from various reactor systems. The Committee believes that the effects of gradual buildup of tritium in liquids within the plant should be carefully evaluated. Factors to be assessed include potential in-creases in radiation exposures of operating ' personnel, possible dif fi-culties in proper plant maintenance, and the possible influence of increased tritium concentrations on the consequences of unanticipated releases.
During the hot functional testing of Oconee Nuclear Station, Unit 1 which was conducted in 1972, damage occurred to some components, including re-3 actor vessel internals. The design improvements made to Ocpnee Nuclear Station, Unit I have been made also to Rancho Seco Unit 1.
The Committee believes that these changes are acceptable.
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Honorable Dixy Lee Ray September 11,'1973 The applicant has been responsive to the Committee's recommendation that suitable instrumentation be sought to monitor for loose parts and for vibration; such instrumentation has been designed and will be util-iz ed.
The applicant has proposed appropriate operating limitations to be applied if, at any time during operation, the moderator temperature coefficient of reactivity is positive.
This matter should be resolved in a manner satisfactory to the Regulatory Staff.
The Regulatory Staff has been investigating on a generic basis the problems associated with a potential reactor coolant pump overspeed in the unlikely event of a particular type of rupture at certain locations in a main coolant pipe.
Some additional protective measures may be warranted,t and this matter should be resolved to the satisfaction of the Regulatory Staff. The Committee wishes to be kept informed.
The Committee reiterates its previous comments on the need for further study of means for preventing common mode failures from negating.r:setor scram action, and of design features to make tolerable the consequer.ces of failure to scram during anticipated transients. The Committee believes it desirable to expedite these studies and to implement in timely fashion such, design modifi~ cations as are found to improve significantly the safety
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of the plant in this regard. The Comaittee wishes to be kept informed of the resolution of this matter.
The applicant should assure himself that instrumentation for determining the course of potentially serious accidents, on a time scale that will permit appropriate emergency action, is provided at the station and that appropriate calibration methods and calculated bases for_ interpreting instrument responses are available.-
In view of the important role of the applicant's Management Safety Review Committee in providing continuing reviews, and in updating and implementing safety measures, the ACRS recommends that the Management Safety Review Com-mittee include additional experienced personnel from outside the corporate structure as voting members.
The applicant has proposed measures, including alarms and administrative procedures, to prevent operating under cenditions which might result in
, v exceeding acceptable fuel limits established from accident studies and other considerations.
The current review has been' confined to the first fuel cycle, and the analyses have been based on the as-built fuel. The ACRS recommends that the Regulatory Staff establish suitable criteria for these measures and provide suitable bases for evaluating future loadings.
The Committee wishes to be kept informed.
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Honorable Dixy Lee Ray September 11, 1973 The Committee recognizes that re-evaluation of operating limits may be necessary as a result of possibic changes in the acceptance criteria for emergency core cooling systems.
The Committee wishes to be kept informed.
Other problems relating to large water reactors which have been identified by the Regulatory Staff and the ACRS and cited in previous reports should be dealt with appropriately by the Regulatory Staff and the applicant an suitable approaches are developed.
The Advisory Committee on Reactor Safeguards believes that, Edue regard,
is given to the items mentioned above, and subject to satisfactory compic-tion of construction and preoperational testing, there is reasonable assurance that Rancho Seco Nuclear Generating Station, Unit 1 can be operated at power levels up to 2772 Mf(t) without undue risk to the health and safety of the'public.
Sincerely yours,
, / /(s h m
H. G. Mangelsdorf c.,
Chairman
Attachment:
List of References O I l
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/*onorable Dixy Lee Ray September 11 1973 3
References 1.
Sacramento Municipal Utility District (SMUD) Safety Analysis Report for Rancho Seco Nuclear Generating Station, Unit 1, Vols. I-V, May, 1971 and Vol. VI, June, 1972 2
Amendments 6 through 23 to SMUD License Application for Rancho Seco 3.
Letter from E. K. Davis, SMUD, to A. Giambusso, L, dated March 23, 1973, " Final Report on Minor Imperfections Found in Pipe Welds at the Rancho Seco Nuclear Generating Station" 4.
Letter from E. K. Davis, SMUD to A. Giambusso, L, dated April 3,1973, "InterLa Report on Fuel Densification" 5.
Letter from E. K. Davis, SMUD, to A. Giambusso, L, dated May 1, 1973,
" Interim Report on Effects of Piping Break Outside Containment" 6.
Letter from E. K. Davis, SMUD, to A. Schwencer, L, dated May 3,1973,
" Review of Control Circuits" 7.
Directorate of Licensing Safety Evaluation, June 8, 1973 8.
, Letter from H; W. Ibser, Professor of Physics, California State University to M.Libarkin, ACRS, dated June 13, 1973, conceening temperature inversions at Rancho Seco 9.
Babcock and Wilcox Proprietary Report, BAW-1393, " Rancho Seco Unit 1 Fuel Densification Report," June, 1973 with supplemental information containing as-built data forwarded by letter from E. K. Davis, SMUD, to 'A. Giambusso, L, dated July 23, 1973
- 10. Report, " Rancho Seco Nuclear Service Spray Ponds Performance Evaluation," dated June 29, 1973 by the Waste Heat Management Research Project, University of California, Berkeley
- 11. Directorate of Licensing Technical Report on Densification of BCR Reactor Fuel, dated July 6,1973 12.
Letter from E. K. Davis, SMUD, to A. Giambusso, L, dated August 2, 1973, submitting changes to the FSAR, and the control scheme for emergency C,.
diesel engines.
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