ML20073T302
| ML20073T302 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/05/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20073T301 | List: |
| References | |
| NUDOCS 8305110228 | |
| Download: ML20073T302 (3) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF-NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 85 TO FACILITY OPERATING LICENSE N0. DPR-65 NORTHEAST NUCLEAR ENERGY COMPANY, ET AL.
j MILLSTONE NUCLEAR POWER STATION, UNIT 2 DOCKET NO. 50-336 i
j
_ Introduction Millstone Nuclear Power Station, Unit 2, is presently preparing for a June-September 1983 refueling outage.
During this outage, the licensee will perform both the 10 year inservice inspection and steam generator sleeving.
Prior to the steam generator sleeving, steam generator channel head decontamination needs to take place in order to reduce the exposure to maintenance personnel.
The licensee has scheduled the steam generator channel head decontamination concurrently with refueling activities.
The technical specifications require that containment integrity be established when fuel is being moved. There.
fore, containment iTitegrity needs to be maintained during the steam genera-tor channel head decontamination.
Steam generator channel head decontamination procedures require a number of hoses and electrical cables to enter containment from the auxiliary building.
In order to find a path for these hoses and cables, the licensee l
has proposed building a temporary containment building equipment hatch i
door.
The new door would provide a path for the hoses and cables to j
support the decontamination process and it would maintain containment I
integrity against a postulated fuel handling accident.
Evaluation i
The Millstone Unit No. 2 containment building includes an equipment hatch, nineteen (19) feet in diameter, to permit transfer of large components into and out of the containment.
It is fitted with a double gasketed flange around the dished door to minimize leakage in the unlikely event of a loss-of-coolant-accident (LOCA).
Technical Specification 3.9.4 specifies the required status of certain l
containment penetrations during core alterations or movement of irradiated fuel within the containment. These requirements ensure that a release l
of radioactive material within the containment will be restricted from leakage to the environment. The radioactive material released from a postulated fuel element rupture would be retained within the building.
8305110228 830505 PDR ADOCK 05000336 P
The temporary equipment hatch door proposed to be utilized during the Cycle 6 refueling ourage will consist of a circular 1/4 inch thick steel plate with stiffeners.
The door will be mounted to the 3/4 inch thick, 8 inch wide, embedded plate which circles the exterior end of the equipment hatch containment penetration.
It will be secured in place by thirteen (13) studs which will be welded to the embedded plate.
An 0-ring gasket is located between the temporary door and the embedded plate to provide an " air tight" seal between the containment and the enclosure building.
Ten (10) six inch diameter penetrations through the door are provided for l
various hoses and electrical cables needed to support the steam generator channel head chemical decontamination project.
The temporary door is designed to maintain primary containment penetration integrity required by Technical Specification 3.9.4 during core alterations or movement of irradiated fuel within the containment. The penetrations will be isolated by blind flanges when not in use.
Penetrations in which cables or hoses pass through will be sealed with silicone RTV fire-resistant foam to provide the required sealing.
The features incorporated into the design of this temporary equipment hatch door. ensure that containment integrity will-be maintained while core alteratipns or fuel movementsaare conducted within the containment considering the negligible pressure gradient which will exist across the equipment hatch penetration.
The ten (10) penetrations will consist of one foot long segments of six inch diameter pipe penetrating the door and welded along their perimeters.
The silicon foam will surround the hoses and cables and completely fill the one foot pipe segment. The silicon foam is quick dr ing and will harden to a rubber-like consistency. Testing of this foam shows that it will stay in place and maintain a vapor barrier.
The hoses and cables will be supported by scaffolding on both sides of the temporary equipment hatch door.
Therefore, the dead weight loads and vibrations of the hoses should not interfere with the integrity of the foam seal.
If one of the foam seal barriers fails during refueling operations, the technical specifications require that all refueling activities be immediately suspended.
Should a fuel handling accident occur and all steam generator channel head decontamination activities 'are suspended, the licensee has i
stated that the hoses will not be a potential leak path.
The licensee also stated that the decontamination system can be isolated within itself.
i During refueling operations, the containment need be protected only for a fuel handling accident. Since we do not postulate high or medium energy pipe ruptures inside containment during refueling, the foam barriers need l
be only vapor barriers and do not need to withstand large differential pressures.
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4 Based on our review and discussions with the licensee, we conclude that the licensee's proposal will provide adequate containment integrity during the proposed refueling outage.
Therefore, we find the proposed modifica-i tions and temporary technical specification change acceptable.
f Environmental Consideration j
We have determined that the amendment does not authorize a change in effluent j
types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this determination, j
we have further concluded that the amendment involves an action which is j
insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 551.5(d)(4), that an environmental impact statement, or negative i
declaration and environmental impact appraisal need not be prepared in connection with the issuance of this amendment.
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j Conclusion We have concluded, based on the considerations discussed above, that: (1) 1 because the amendment does not involve a significant. increase in the proba-bility or consequences of an accident previously evaluated, does not i
create the possibility of an accident of a type different from any evaluated i
previously, and does not involve a significant reduction in a margin of safety, the amendment does not involve a significant hazards consideration, (2) there is feasonable assurance that the health and safety of the public j
will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
i Dated: May 5, 1983 Principal Contributors:
j Louglas Pickett, ORAB:DL Dennis Kubicki i
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