ML20235B662

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Preliminary Rept to Acrs
ML20235B662
Person / Time
Site: 05000000, Zimmer, 05000359
Issue date: 11/05/1970
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US ATOMIC ENERGY COMMISSION (AEC)
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FOIA-87-111 NUDOCS 8709240181
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0FH01AH18E-0titY Docket Nos. 50-358 November 5,1970 j and 50-359 Preliminary Re port to the ACRS Wm. H. Zinmar Nuclear Power Station Units 1 and 2 U.S. Atomic Energy Commission Division of Reactor Licensing WICIAL-USE O!LY 8709240181 870921- ge .

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1.0 INTRODUCTION

on April 6,1970, the Cincinnati Gas and Electric Company (CG&E),

Columbus and Southern Ohio Electric Company (C&SOE), and Dayton Power and Light Congdny (DPL), the applicants, filed an application for licenses required for the construction and operation of the pro-posed Wm. H. Zimmer Nuclear Power Station. The Zineer station will consist of two identical single-cycle, forced circulation, boiling water reactor units, constructed near Moscow, Clermont County, Ohio, 25 miles southeast of Cincinnati, on the Ohio River. The Cincinnati Cas and Electric Company (CG&E) is responsible for the design, construc-  :

tion and operation of the Ziauner Plant and is also authorized to t.et as agent for C&SOE and DPL in all details of construction, including licensing.

The applicants have retained Sargent and Lundy to perform architectural engineering work, and the General Electric Company will design, fabricate and deliver the single-cycle, boiling water nucisar steam supply system for Units 1 and 2. The plants will utilize the new General Electric 1969 product line core standby cooling systeam. The General Electric Company will also fabricate the first core of nuclear fuel for Unit 1. I A construction contractor has not yet been chosen. The turbine generator unit for Units 1 and 2 will be supplied by the Westinghouse Electric Corporation.

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._ggletAth.c beh of the two reactor units is rated at 2436 MWe and 807 MWe. All safety systems and analyses will be evaluated at the design power levels of 2540 We and 840 Wo. The proposed plant is similar in '

many respects to the Edwin I. Hatch Nuclear Plant No.1, now under con-struction by the Georgia Power Company. The significant differences between the Zimmer and Hatch nuclear steam systems are discussed in Section 2.0. Table 1.0 provides a comparison of signifier.nt differences between the Wm. H. Zinner and Edwin I. Hatch facilities. Hyperbolic natural draft cooling towers will be used to dissipate waste heat to the atmosphere.

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- 1- Table 1.0 Comparison of Desilta Characteristics Ites' mm. H. Zinener ' Edwin I. Hatch

  • Reactor Coolant Recirculation Loop Design Flow Control . Throttling With An Recirculation Pump Additional Valve- Speed Ptnup Flow Rate, spa / pump 33,880 45,200 Total Core Flow Rate, lbs/hr 78.5 x 10 6 75.5 x 106-Nominal Pipe'Sise, inches 20 28 Core Spray System Number 'of Systaas 2** 2 Pump Flow Rate and Pressure -

gpa (psid)*** 4625 (119) 4625 (119) 1330 (1130) ljiyh Preneure_ Coolant Injection Sys te:n Coolant Injection Mode Spray Flood Injection Method Directly into core via Indirectly into core core spray sparger via feedwater sparger Flow Rate, gpm (psid). 1330 (1130) 5000 (150-1130)

Ptsap Motive Type Motor Driven with sep- Steam Turbine Driven arate Diesel generator

  • The Edwin I. Hatch Nuclear Facility has the same equipment arrangement 'as other BWR facilities such as Browns Ferry,~ Peach Bottom, and Enrico Fermi.

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- No. of Pumps 3 .4 Flow Rate, gpm/ pump (psid) 5050 (20) 7700 (20) (

h loop Selection Logic None Sense Break Location Injection Method Top of Core **** Recirculation Loop Piping d

Primary Containment

-Concept Over & Under Pressure Pressure Suppression Suppression - (Lightbulb)

Construction Type Prestressed Concrete ASME Steel Pressure Steel Lined Vessel Drywell Geometry Frustrum of Cone Light Bulb Shaped

. Pressure Suppression Cylindrical Tocus Chamber (PSC) Geometry -

PSC and Drvvell Internal Design Pressure, psig 45 56

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j 2.0 AREAS OF REVIEW-In our review of the construction permit for the proposed facilities, special attention will be given to the following areas:

2.1 Geolony and Seismolony The bedrock surface is located from 83 to 88. feet below ground.

Consequently, the major structures will be supported.on piles. The upper 30 to 35 feet of soil is recent alluvial deposit, therefore, our concerns involve slope stability and ground water level that could significantly increase liquifactica potential under the floods:d condition.

We have met with our seismic consultants on matters pertaining to th-s Zirr.er propeved uccimum ground acceleration values of 0.10g (Design Basis Earthquake) and 0.0$g (Operating Basis Earthquake).

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r At the present time we are act convinced of the applicants' contention that the seismic activity of the Anna area located

' 90 - 125 miles from the site, could not occur anywhere on the Cincinnati arch, upon which the Zimmer site is located. If a seismic event could occur anywhere on the arch, then the ground acceleration values for the site would significantly increase.

f I We intend to review these areas in detail.

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.2.2 Hydrology Based on our review of the Zimer application, it appears that the plant flood protection level is designed for three feet higher than the maximum. recorded flood (1937) level of 517 feet. We requir'e nuclear plants to have design provisions to safely accommodate the Probable Maximun Flood (PMF) as defined by the U.S. Army Corps of Engineers. Preliminary escimates show that the PMF peak discharge 6 6 at the site would be in the range of 2.2 x 10 to 2.6 x 10 cfs which would result in a flood level in excess of 517 feet. We have initiated our review of this area.

2.3 Meteorology i

The applicants' proposed site meteorology used to calculate postu-lated doses was based on Pasquill Type F condition with wind speeds of 1 m/sec. The 5-year meteorological data ottained from the Greater Cincinnati Airport indicate that Pasquill Type G with average wind speeds of 0.75 m/sec. or less should have been used. Therefore, we I will evaluate, in detail, the applicants' justification for using their proposed meteorological conditions.

Because the Zimer facility will utilize a natural draf t hyperbolic cooling tower and a large stack for radioactive discharge, the -

l_ following interacting ef fects between cooling towers and stack will be reviewed:

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s. downwash from the natural draf t hyperbolic cooling towers on the releases from the 125 meter stack, ,
b. collapsed cooling te'rer or stack on each other, and other site buildings, and
c. elevated stack releases and local topography (nearby hills) on the calculations of potential doses at the site boundary.

2.4 Recirculation loop The recirculation loop piping system has been modified so that an additional valve (globe valve) is used to regulate the flow through the core, rather than utilizing the recirculation pumps.,

as was the case for previously reviewed BWR designs. The piping njstem is a raore craapact system with shorter lengths and smaller diameter recirculation lines. This modified piping will have higher flow rates and may require increasing the inertia of the pumps to provide sufficient flow during a pump trip. However, it is not known whether flywheels will be used to develop the increased inertia.

Also, the smaller diameter recirculation lines reduce the effective break area for the design basis double-ended line break.

The recirculation flow rate for the Zimmer facility is significantly less than the flow rate of similar BWR facilities. Also, the total l .

developed head is higher but the total jet pump flow is about i

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J1FF 0 the same. This could af fect the jet pump perfomance characteristics; therefore, this area will be evaluated to assure that t.he jet pump design falls within the experimental design limitations. l 1

2.5 containment The secondary containment is the same as for other BWR stations. The primary containment design differs fvom other nuclear plants in that:

the drywell (a steel-lined frustrum of a cone) and the vapor suppression chamber (a right-circular cylinder) are constructed from prestressed concrete. The pver-and-under vapor suppression system is separated by a reinforced concrete slab which also functions as the drywell floor.

The over and under concept differs from other vapor suppression systema, in that the ratio of vent area to break area is large, which makes the vent flow model less sensitive to the size of the primary system rupture assumed. The design pressure is 45 peig and the calculated maximum pressures after blowdown in the drywell and in the suppression chamber are 36 and 32 psig, respectively. The des?.gn of the primary containment will receive particular attention in our review.

2.6 Core Standby Cooling System A new core standby cooling system (CSCS) has been proposed for the Zimmer Plant. The General Electric Company submitted its Topical

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Report No. NEDO-10183 on June 1,1970, for our review and considera-tion. This report discusses and evaluates the.CSCS in detail which

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.(a) High Preasure Core Spray (HPCS)- The new HPCS system combines the function of the former high pres-sure coolant injection (HPCI) sys-tem and one of the core spray systems of previoum BWR plants, i.e., a single pump will be used to perform both functions. The pump characteristics are selected to satisfy the high head and low flow requirements for the core spray function. Power for the HPCS will be provided by a separate diesel generator. In addition to functioning as a low pressure core spray system, the HPCS injects the

. water directly through the core spray sparger, rather than through the feedwater sparger, as was the case in earlier BWR designs.

(b) Automatic Depressurization System (ADS) The ADS remains unchanged from previous BWR systems.

t (c) Low Pressure Core Spray I l

System (LPCS) The LPCS system is identical to other BWR systems except that only one loop will be provided fo'r Zinner. The HPCS will serve as the redundant core spray loop.

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(d) Low Pressure Coolant Injection System (LPCI) The LPCI system will inject water from the suppression pool directly into the top of the cpre through three separate nossles in contrast to previous BWR designs which used the recirculation loop piping system for injection of water.

Because of this feature the loop selection logic used,on previous BWR designs was eliminated; i.e.,

it is not 'necessary to sense break location.

The General Electric Company met with an ACRS Subcommittee on July 23,1970 and with us on September 10'11, 1970 to discuss the new CE-CSCS. Our preliminary cosaments on the CE-CSCS vare transmitted to the General Electric Company on October 13, 1970. The matters discussed in that letter will be included in our review of the proposed Zicser Core Standby Cooling System.

2.7 Instrumentation and Control J

We understand that the General Electric Company intends to modify certain aspects of the instrumentation and control system, to include solid state circuitry rather than the relaying now used. However, the application does not presently include a description of the proposed changes.

2.8 Quality Assurance Program The quality assurance program of the Cincinnati Cas and Electric (CC&E) Company and its relation with the QA/QC programs of the con-J)FFICIAtWe&Y.%

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struction contractor and the General Electric Co. will be evaluated.

A detailed evaluation'ia considered necessary since this is the-

. first involvement of CG&E in the overall quality assurance program

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3.0 REVIEW SCHEDULE We expect to complete' oud review in time for corasideration by the Committee during the April 1971 Session. This would permit issuance of a construction permit no earlier than July of 1971.

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