ML20125B133

Safety Evaluation Re Piqua Nuclear Power Facility Retirement.T Hamrick to J Schlesinger Encl

ML20125B133
Person / Time
Site:	Davis Besse
Issue date:	12/16/1968
From:	Skovholt D US ATOMIC ENERGY COMMISSION (AEC)
To:
Shared Package
ML20125B130	List: ML20125B128 ML20125B133
References
NUDOCS 7910240190
Download: ML20125B133 (4)

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SATETY EVALUATION BY TRE DIVISION OF R ACTCR LICENSING

' DOCKET do. 115-2 THE CITY DF PIQUA .

PIQUA NUCLEAR POWER FACILITY RETIRI"ENT INTRODUCTION The Piqua Nuclear Power Facility (PNPF) is an organic-coderated and -cooled power deconstration reactor'which was operated by The City of ?iqua (COP) at its site in Piqua, Ohio. The nuclear steam generating part of the facility is evned by the Atomic Energy Co= mission and the cenventional facilities are evned by C,0P. As a Co==ission-owned facility,' construction and operation vere authorized in accordance with the Cc==ission's regulation, " Procedures for Review of Certain Nuclear Reactors Exempted frem Licensing Requirements,"

10 CTR Part 115. PNPF was shut dean in January 1966 when coke-like material, formed by dece= position of the reactor coolant, caused certain of the reactor ce=ponents to beceme distorted. After extensive review, the Co= mission determined that the PNPT technology had licited potential use for the adva'nced types of reactor concepts currently being developed by the Co= mission, and announced in December 1967 that it would terminate the contract for operation of the facility.

Following ter=ination of its operation, COP has unloaded the nuclear fuel

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.nd organic coolant 'from the reactor. The fuel has been returned to the

, Ce= mission. With the removal of this equipment, no highly radioactive equiprent remains in the plant except within the reactor ce= plex, i.e., the- -

reactor vessel, .its shielding, and various internal ce:ponents. COP was '

authorized by a Commission order dated August 7,1968, to perform partial

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v i dismantlement of the facility by the removal and disposal of those low-activity components not considered necessary for the continued maintenance cf the reactor building containment. This work is now in progress.

By letter dated September 3,1968, CDP submitted "PNPF' Retirement Plan" and "PNPF Safety, Analysis Report" and requested authorization to proc.eed with the re=aining dismantlement and final retirement of the facility.

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The proposed retirement plan consists of:

, 1. Intomtrent of the reactor complex in place, and

2. Decentamination and res toration of the buildings and grcunds to a conditien suitable for unrestricted occupancy and use as a vare'.;.ous e f acility.

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Since the dismantle =ent and removal of equipment external to the reactor cerplex has been previously evaluated and authorized by a Ce==ission order, these activities will not be discussed herein.

C*_SCUSSION As mentioned above, no highly- radioactive cateriad new remains within the plant.except for the reactor co= plex, i.e., the biolegical shield, the reactor vessel and internal components. COP has prcpcsed a detailed plan for permanently entomb'ing the complex in place to prevent access to the caterial enclosed and to prevent the escape of radioactivity to the surroundings.

All piping that penetrates the concrete biological shield vill be cut off and welded closed. The reactor vessel closure head will be bolted to the vessel and the vessel will be pressure-tested to verify leak-tightness. The tcp shield plug will be installed over the reactor vessel and welded in place. A waterp' roof. barrier vill then be placed over the entire main flor,r area with the exception of stairvells and hatches and will in turn be cesered by a layer of reinforced concrete which will form the new cain floor.

C:her below-grade volumes, such as instrument thichle pits, rail trenches, and the fuel. storage pool vill be filled with concrete or sand prior to installation of the new concrete floor slab.

The steel shell of the reactor building which extends 50 feet below grade level will provide a further ba'rrier to access to the ento = bed caterial or to leakage to the surroundings. An existing cathodic protection system vill be maintained by COP to prevent future corrosion of the shell by ground ccisture. In addition, the reactor buildin,g sump is provided with a pu=p and a high-water-level alarm which will continue to be caintained by COP personnel to preclude accumulation of water within the building.

The recaining. usable areas of the reactor and auxiliary buildings wi11 be decontaninated as required to meet the requirements of 10 CTR Part 20 for unres tricted areas. Building services, such as heating an8 ventilation, lighting, fire pro:ection, waste disposal, and drinking water will continue te he previded.

Frier to terninstion of the f acility authorizz: ion, a res trictive covenant v:?. be placed in the land records of Miami County, Ohio, describing the 4:ure ef the radicactive material lef: in place at the site, and prohib-1:ing any action which right disturb it or tend to impair its integrity.

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The :".:f reac:cr cenplex is estinated to cen:ain a :c:a1 of approxicately i: ^:: :::ies cf radicactivi:y at the present time. F.cw e v e r , since the l l

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facility was designed to contain the far greater radioactivity generated by En operating nuclear reactor, radiation levels in accessible areas of the plant will be within the limits specified in 10 CFR Part 20 for unrestricted

, creas when the retirement plan is completed.

The radioactivity contained in the reactor complex is in the fer= of acti-vation products, produced during operation, in the reactor and shielding structure. No; fission products remain since all the fuel has been iemoved frem the facility. The activation products remaining, chiefly iron-55 and cebalt-60, are contained in their parent materials such that their rapid release is not possible. Moreover, since there is no energy source available within the reactor complex, there exists no means by which radioactive materials could be rapidly expelled to the environs. Thus , in the event of

a. severe natural catas trophe, such as earthquake or flood, that could result in datage to the reactor' complex or building structure, suf ficient time would be available for remedial action before any of the contained radio-activi:y could escape. However, such damage is unlikely, since the facility was originally designed and censtructed to prevent' damage to an operating r.eacter under such conditions.

As dbscribed above, specific measures will be taken to prevent the long-t e r: corrosion of the activated materials and subsequent release of radio-activity to the surroundings. The radioactive materials will be below grade level, sealed in a n.assive concrete structure. The applicetion of a water-proofing material to the top surface of this structure and the laying of a new concrete floor, as proposed, will effectively prevent the entrance ci,wa ter from above. As noted previously, the steel shell of the reactor building will provide an additional barrier to water below grade. However, even if this barrier were to fail, we conclude that the provision of a water level alarm and pu=p in the reactor building sump, as proposed, will pe rmit the discovery and re= oval of any accumulated wa'ter before it reaches the level of the reactor complex.

I An analysis of the amounts of activation products present in the facility

' snd : heir rates ef decay indicates that all restrictiens en entering the

ot c omplex could be removed in about 120 years withcut violating the a;; c;ria:e irti:s in 10 CTR Fart 20 for unrestricted areas. We have con- '

ciudcd : Sat the p rc pes ed re thod of entombrer.: of the reactor e c=p".ex will

"ide adecut:e containment of the enclosed radioactivity for this length

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: ':~;AT:05 A:O F;.DCDUPIS The prc;esed retirerent plan fer the FNFT was develeped by C0p and the designer f ; c.e f acility, At emics internatienal . The procedures to be followed e

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during the course of the work already exist as approved operating or main-tenance procedures. Any additional procedures required or safety consid-ekatiens that arise will be reviewed by the exis t ing ?::.:7 S e.f e t;. Review Committee. Additional outside assistance will be provided by Eattelle

'"emorial Ins titute, which will act as consultant _to COP.

The issuance of an order authorizing dismantling of the facility will, in effect, supersede the Technical Specifications for cperatien of the facility and thus obviate the need for changes to the individual specifications as the dismantling progresses. In its application, the COP has proposed ad=in-istrative controls to be in ef fect during the time that the retirement plan

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is being carried out. We have determined that these centrols are adequate to assure the safety of the personnel and the public during the dismantling.

CONCLUSION On the basis of our review of the retirement plan proposed for the Piqua Suelear Power pacility, we have concluded that the. dismantling of the j "ec'lity and the disposal of its component parts as proposed will be per-f'rmed in acccidance xith the Co= mission's regulations and will not be l aimical to the co= mon defense and security or to the health and safety c.f the public. -

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Donald J. Skovholt Assistant Director for Reactor Operations Division of Reactor Licensing . cr

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Date: ^'svir

' v' December 16, 1968

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