ML20148F180

Forwards Missing Page from Rev 34 to MITNE-115, SAR for Mit Research Reactor (MITR-II)

ML20148F180
Person / Time
Site:	MIT Nuclear Research Reactor
Issue date:	03/21/1988
From:	Lisa Clark MASSACHUSETTS INSTITUTE OF TECHNOLOGY, CAMBRIDGE
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8803280083
Download: ML20148F180 (2)

Text

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? NUCLEAR REACTOR LABORATORY I/p- : W AN INTERDEPARTMENTAL CENTER OF Q MASSACHUSETTS INSTITUTE OF TECHNOLOG(

O.K. HARLING 138 Albany Street Cambridge, Mass. 02139 L CLARK, JR.

Director (617) 253- 4202 Director of Reactor Operations March 21, 1988 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Subj ect: Submission of SAR Revision No. 34, pursuant to Technical Specification 7.13.3b, License No. R-37, Docket No. 50-20, Correction Gentlemen:

The Nuclear Reactor Laboratory of the Massachusetts Institute of Technology submitted with its letter of March 8,1988, Revision No. 34 (four copies) to the "Safety Analysis Report for the MIT Research Reactor (MITR-II)", Report No. MITNE-115 (October 22, 1970), as amend-ed. That submission was incomplete in that SAR page no. 6.1-5, dated March 8, 1988, was inadvertently omitted.

The missing page (four copies) it, forwarded herwith and should be inserted in Section 6.1 between pages 6.1-4 and 6.2-1.

Please accept our apologies for any inconvenience caused by this omission. i Sincerely, fA YY r Lincoln Clark, Jr.

LC/CRH

Enclosures:

SAR page no. 6.1-5 cc: MITRSC USNRC, Region I - Chief, Reactor Projects Section IB USNRC, Region I - Projects Inspector USNRC, Resident Inspector Pilgrim Nuclear Station j Dco / ,

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I A flow rate of 3.25 gal / min (or five times higher) will assure that all elements receive adequate cooling spray even though the flow per element may be only 20% of the average due to shadowing by experi-ments. The 10 gal / min required by Technical Specification 3.6-1 is more than adequate by a factor of three and is more than enough to compenaate for the ineffectiveness of spray water that may fall the full length of a coolant channel (0.078 inches wide by 23 inches long) without absorbing heat from a fuel plate. The channel area represents less than half the core area, and it is highly unlikely that much, if any, water could fall through the core without contacting a plate.

While the above analysis accounts for non-uniformity of ECCS spray from element to element, the non-unif ormity within an element has also been considered and found ' acceptable. If the water for an element runs down the fuel element side plates, so that cooling of the fuel plates is by conduction to the side plates only, a conservative calculation (which assumes that the thermal conductivity of the uranium-aluminide fuel matrix is negligible compared to the aluminum ,

cladding) shows that the fuel plate centers will be only 45'F hotter than the side plates. Hence, adequate cooling would easily be pro-vided by cooling the side plates only.

The possibility that "flooding" might occur was also considered, i.e., the blocking of ECCS spray down-flow into the core by the veloc-ity of steam and/or air being ejected upward out of the core. Flood-ing calculations based on the method described in One Dimensional Two-Phase Flow by Graham Wallis show that flooding will not occur for the decay heat rate at 8.5 minutes after shutdown. This conclusion was confirmed by an experiment with a dummy fuel element in which air flowing upward at relatively high velocity failed to impede the down-ward flow of cooling water, i.e. did not cause flooding.

The above analysis is conservative because it takes no credit for conduction of heat to the fuel element end-adapters, the core housing SR#-0-87-19 MAR 8 1988