05000318/LER-1981-028-01, /01T-0:on 810613,C-E Informed That Pipe Fittings Immediately Upstream of RCS Code Safety Valves Did Not Have Proper Inner Diameter.Caused by Min Pipe Specs for Valves Not Being Properly Stated on Interface Drawings

/01T-0:on 810613,C-E Informed That Pipe Fittings Immediately Upstream of RCS Code Safety Valves Did Not Have Proper Inner Diameter.Caused by Min Pipe Specs for Valves Not Being Properly Stated on Interface Drawings

ML20008G268
Person / Time
Site:	Calvert Cliffs
Issue date:	06/26/1981
From:	Davis S BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20008G266	List: 05000318/LER-1981-028, Forwards LER 81-028/01T-0 05000318/LER-1981-028-01, /01T-0:on 810613,C-E Informed That Pipe Fittings Immediately Upstream of RCS Code Safety Valves Did Not Have Proper Inner Diameter.Caused by Min Pipe Specs for Valves Not Being Properly Stated on Interface Drawings
References
LER-81-028-01T, LER-81-28-1T, NUDOCS 8107070226
Download: ML20008G268 (2)

LER-1981-028, /01T-0:on 810613,C-E Informed That Pipe Fittings Immediately Upstream of RCS Code Safety Valves Did Not Have Proper Inner Diameter.Caused by Min Pipe Specs for Valves Not Being Properly Stated on Interface Drawings

Event date:
Report date:
3181981028R01 - NRC Website

text

NRC FORM 366 U.S. NUCLEAR REGULATcRY COMMISSION (7 77!

LICENSEE EVENT REPORT CONTROL BLOCK:

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60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h I O 121 l Combustion Engineering infonned the plant that pipe fittings immediately l

ITTT1I upstream of the RCS code safety valves do not have a proper ID (T.S.

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[ TIT 1 l 6.9.1. 8.h ). The reduced ID will invalidate assumptions used in analysis j

pr1T) l of events which result in actuation of safety valves. Analyses recently j

O s l performed for EPRI demonstrated a large margin in sizing of safeties.

l [TTTll Therefore, it is concluded that ti e reduced ID does not constitute a l

l 0 ia i i safety hazard. Similar events: h)ne l

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CODE TYPE NO.

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33 34 35 36 37 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 Ii10ll The minimum oice ID of 21/2 inches for the Dresser Ind. Model 31739A 1

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_ safety valve was not exolicitly stated on their interface drawinas Of I

mI the 1970 vintage. Based on the large design margin, no corrective j

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NAME OF PR@ PAR @Ru PHONE:

4 LER No.

81-28/IT DOCKET NO.

50-318 LICENSE NO.

DPR-ti9 EVENT DATE 06-13-81 REPORT DATE 06-26-81 ATTACHMENT EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (CONT'D)

On Saturday June 13,1981 the Combustion Engineering Site Representative informed the Plant ! perintendent that the pipe fittings immediately upstream of the Reactor Coolant System (RCS) code safety valves do not have a proper inside diameter (T.S. 6.9.1.8.h).

Calvert Cliffs Units 1 and 2 were designed and constructed with 21/2 inch schedule 160 pipe and,1500 pound fittings immediately upstream of their Dresser Model 31739A Safety Valves. These fittings have an inside diameter of 21/8 inches.

The reduced inlet pipe diameter for these valves will reduce the valve discharge capability and invalidate the assumptions in plant overpressure protection and any safety analyses which result in actuation of the pressurizer safety valves. While it is not possible to precisely predict the change in discharge capacity, it is believed to be small since the actual bore diameter of the Model 31739A Valve is only about 17/8 inches.

Since the valve bore is the limiting flow area, the only effect a short length upstream restriction will have is to modestly reduce the pressure upstream of the flow nozzle thereby modestly reducing the critical flow rate.

Parametric contingency analyses recently performed in support of the EPRI Safety and Relief Valve Test Program (EPRI Project V102-20) have demonstratd a large margin in the sizing of the pressurizer safety valves for Calvert Cliffs. Based on the licensing methods for these plants, the calculated required safety valve capacity is more than an order of magnitude below that specified for the plant. It is unlikely that the reduced valve capacity resulting f rom the smaller inlet piping could have a significant impact in light of this large design margin. Therefore, it is concluded that the above described reduction in inlet pipe diameter for the Dresser Model 3173fA Safety Valve does not constitute a safety hazard for Calvert Cliffs Units 1 and 2 l

l CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (CONT'D) l l

The Dresser interface requirements for this model valve is a minimum upstream inside i

diameter of 21/2 inches, although this was not explicitly stated on their interface I

drawings. Based on the conclusion that the reduced pipe diameter does not present a safety hazard, no corrective action will be required.

1 Letter to W. 3. Lippold (BG&E) from P. W. Kruse (CE) dated June 16,1981.