ML20151Z446
| ML20151Z446 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 08/19/1988 |
| From: | Mroczka E, Sears C CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| TASK-2.K.3.05, TASK-2.K.3.30, TASK-2.K.3.31, TASK-TM B12977, NUDOCS 8808290333 | |
| Download: ML20151Z446 (2) | |
Text
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er NORTHEAST UTILITIES cenero Omces. seieen street, seriin. connecticut I
P.O. BOX 270
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(203) 665-5000 August 19, 1988 Docket No. 50-213 B12977 Re: TMI II.K.3.5 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555
Reference:
(1)
W. G. Counsil letter to J. A. Zwolinski, "Small Break LOCA Topical Report, TMI Action Plan Items II.K.3.5, II.K.3.30, and II.K.3.31," dated December 20, 1984.
Gentlemen:
Haddam Neck Plant Resolution of Till Action Plan Item II.K.3.5 Automatic Trio of the Reactor Coolant Pumos During a July 26, 1988 telephone conversation, the NRC Staff requested a clarification of the Connecticut Yankee Atomic Power Company (CYAPC0) response to TMI Action Plan Item II.K.3.5 which referred to reactor coolant pump (RCP) trip criteria during a loss-of-coolant accident (LOCA).
In Reference (1),
CYAPC0 submitted the topical report which documented the response to TMI Action Plan Items II.K.3.5, II.K.3.30 and II.K.3.31.
This letter summarizes the conclusions derived from the report.
The evaluations performed of the effect of RCP operation on small break LOCAs have determined that it is not necessary to trip the pumps to assure acceptable emergency core cooling system (ECCS) performance at the Haddam Neck Pl ant.
The basis for this verification is documented in the Reference (1)
Topical Report (Sections 2.6.3, 2.6.3.5 and 2.6.7).
An evaluation of a spectrum of hot leg breaks with the RCPs on or tripped at varioustimesguringtransientsdemonstratedthatthepeakcladtemperatureis less than 1000 F.
The reasons for the less limiting nature of small breaks with the RCPs in operation are:
o Operation of the RCPs provide forced convection cooling which reduces the magnitude of clad temperature rise.
o The high pressure safety injection (HPSI) pumps at Haddam Neck have a high capacity and are able to match core inventory boiloff very early in the transient.
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U.S. Nuclear Regulatory Commission 812997/Page 2 August 19, 1988 o
Operation of the RCPs during a hot leg break provides a 25% increase in HPSI flow delivered to the RCS because there is no potential for emergency core cooling spillage characteristic of cold leg breaks.
Although RCP operation increases the c,nillage from a hot leg break, the high capacity of the HPSI pumps at Haddam Neck prevents the situation predicted for plants with lower capacity pumps.
The justification for not tripping the RCPs for steam generator tube rupture events is contained in the Westinghouse Owners Group guidelines for pump trip criteria.
Leaving the pumps on is beneficial for tube rupture transients because:
o RCP operation facilitates RCS pressure control necessary to minimize primary to secondary leakage.
o Forced circulation enables a faster and more controlled RCS cooldown.
Reference (1) provides the analytical basis for RCP trip criteria. Acceptabie ECCS performance is achieved regardless of whether or not the pumps remain in operation during a small break LOCA or steam generator tube rupture transient.
The only criterion governing the pump trip is to prevent damage to the pumps during the course of these events.
The CYAPC0 Emergency Operating Procedures direct the plant operators to secure the RCPs during the LOCA and non-LOCA events if either a HPSI or a charging pump is operating and the primary system pressure falls below 1150 psig (1380 psig for adverse containment conditions).
If you have any questions on this information, please contact our licensing representative.
Very truly yours, CONNECTICUT YAfiXEE ATOMIC POWER COMPANY b-fct l
i E. J. Mroczka l
Senior Vice President C
WVL By:
C. F. Sears Vice President 1
cc:
W. T. Russell, Region 1 Administrator A. B. Wang, NRC Project Manager, Haddam Neck Plant J. T. Shediosky, Senior Resident Inspector, Haddam Neck Plant 1