ML20114E751

Answer Submitted by Util to ASLB 790418 Questions Re Impact of TMI Type Incident on Spent Fuel Pool.Question 1 Has Been Withdrawn & Objection Taken to Second Part of Question 3. Postulated Series of Events Could Not Occur at Plant

ML20114E751
Person / Time
Site:	Salem
Issue date:	06/19/1979
From:	Wetterhahn M CONNER, MOORE & CORBER
To:
Shared Package
ML18079A539	List: ML20114E751
References
NUDOCS 7907130314
Download: ML20114E751 (4)

Text

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c UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Before the Atomic Safety and Licensing Board In the Matter of )

)

PUBLIC SERVICE ELECTRIC & GAS ) Docket No. 50-272 COMPANY, et al. ) (Proposed Issuance of

) Amendment to Facility (Salem Nuclear Generating ) Operating License Station, Unit 1) ) No. DPR-70)

LICENSEE'S RESPONSE TO LICENSING BOARD'S QUESTION 1 AND PART 1 OF QUESTION 3 RELATING TO IMPACT OF A THREE MILE ISLAND TYPE INCIDENT ON THE SALEM UNIT 1 SPENT FUEL POOL Based on the information on the Three Mile Island (TMI) incident that has been released by the NRC, the accident ap-parently resulted in the release of radioactive fission products contained in the fuel rod gaps (void spaces between the uranium dioxide fuel pellets and the zircaloy cladding) in the reactor core due to clad failure. The gap activity was released to l

the primary reactor cooling water, a portion of which was )

spilled onto the reactor containment floor. Some of the ,

gaseous activity.in the released reactor coolant, particularly structure.

noble gases, became airborne in the containment The spilled reactor coolant collected in the containment sump, where a portion was pumped into the auxiliary building Some of this water spilled onto liquid waste storage tanks.

the auxiliary building floor, resulting in the radiation levels 7907130 3/Y b N 010

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measured in the auxiliary building and substantially all o the radiation levels in the surrounding site environs.

i With regard to the Board's first question, inasmuch as f

TMI Unit 2 had only recently started up, no fuel was stored in the spent fuel pool.

In order to address the first part of the Board's third the effect of a TMI type incident on the question, i.e._,

Salem Unit 1 spent fuel pool, an analysis was performed in from which a release of all the fuel rod gap radioactivity

'the Salem Unit 1 reactor core into the reactor coolant system was postulated. It was further assumed that all of the noble gases released to the reactor coolant became Finally, it was airborne in the containment building.

postulated that radioactivity would be released' into the auxiliary building in the area of the radwaste system storage tanks.

While, because of differences in design between the TMI units and the Salem units, the postulated series of events to could not occur at Salem Station as they did at TMI, respond to the Board's question, the above described events were assumed to occur for the purpose of this analysis.

there would be Even in this postulated set of circumstances, no significant impact in the fuel handling building where l

the fuel storage pool is located or on the spent fuel poo itself.

The fuel handling building walls in the area are 6 ft. thick at eleva-adjacent to the reactor containment

.by (I t lI~

O fl

e tions up to 30 ft.

above grade (this corresponds to elevation and 2 ft. thick at higher 130 which is the operating deck) 1/2 ft.

clevations. The reactor containment walls are 4 thick.

Radiation levels in the fuel handling building from lu the direct radiation in the primary containment were ca c -

Even this radiation lated to be less than 10 mrem / hour.-

level, which was calculated to occur only only in one small area, would not preclude access to the fuel handling building.

Components of the spent fuel pool cooling system that are not located in the fuel handling building are located in l

areas of the auxiliary building that are separated by severa feet of concrete from,the liquid waste storage tanks, which Hence, are themselves contained in individual compartments.

high radioactivity in those tanks or compartments would not prevent access to spent fuel pool cooling system components.

The auxiliary building ventilation system is designed to pre-il vent the movement of airborne radioactivity from one potent a Thus, any contaminated area of the building to another.

gaseous activity released from spills in the liquid radwaste fuel system would not contaminate areas associated with spent pool cooling system components.

The fans and filtering equipment in the fuel handling building ventilation system are located in the penetration (i.e., ground level) between the area at elevation 100 ft.

Since this equipment containment and auxiliary building.

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is operat'ed remotely from the Control Room, access to this In any event, maximum equipment is normally not required.

radiation levels, which are calculated to be less than 300 If ,

mrem / hour, would not be high enough to preclude access. i l

necessary, dose levels could be significantly reduced by placing temporary shielding in f ront of the personnel access hatch in the penetration area, the primary contributor to A single row of lead the radiation level in the area.

bricks would reduce the radiation level to less than 1 mrem / hour. '

Based upon the above, it can be concluded that a TMI type incident would not result in any significant adverse impact on the storage of spent fuel in the Salem spent fuel pool. Furthermore, the impact of such an incident is in-dependent of the espacity of the Salem fuel storage pool or the type of racks contained therein.

i I

N B j

_ . _ _ . _ )

1 State of Washington )

) 55 County of Benton )

hF10AVIT OF THOMAS G. ECKHART Thomas G. Eckhart, being first duly sworn according to law, deposes and states:

The Atomic Safety and Licensing Board requested additional information regarding the p,y,n ties of Zircaloy-4 cladding used in the fabrication of Saless fuel. The question was raised in reference to a test perfomed by Exxon Nuclear Co. wherein a stress of 20,000 psi was calculated on the outer row of fuel pins in a 17 x 17 fuel bundle utilized

- in the Sales reactor inserted in a storage call which had been subject s

to internal pressure due to simulated corrosion. This stress level was based upon an experiment in which a portion of an acte.s1 cell was subjected to pressures which would be experienced if a Salem fuel storage cell had a hole at the bottom.

Zircaloy-4 has a minimum unirradiated yield strength greatst i than 55.000 psi and an ultimate strength greater than 70,000 psi.

As testified to at the' hear'ng, the yield strength would increase if the l fuel assembly was irradiated. On Page 4 of Exhibit 1-H, it is reported that the 20,000 psi stress level compared to a yield strength of 30,000 psi. The yield stiength of stainless steel of 30,000 psi we's inadver-  !

tently stated in thE Applintion and should have been indicated as 55,000 psi as discussed above. This error does not change any other

' aspect of this analysis.

• Nuclear Reactor Materials, C.O. Smith, Addison - Wesley Publishing.

Company. 1967 7907 2 30 ,$/9 359 OM

, A.. Signature

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