ML20203N647

Forwards Responses to Rl Lloyd Questions Raised During Recent NRC Safety Sys Outage Mod Installation Insp.Data Sheets Designed to Accomodate Adjustments & Recalibr Check

ML20203N647
Person / Time
Site:	Dresden
Issue date:	09/29/1986
From:	Wojnarowski J COMMONWEALTH EDISON CO.
To:	Konklin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
References
2166K, NUDOCS 8610090380
Download: ML20203N647 (2)

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• ' o [ 4 }~ 72CWest mm:nwIcith Edison Adams Street. Chicago, Illinois N

k' Address Reply to: Post OfficeBox 767 Chicage, fi'inois 60690 0767 September 29, 1986 Mr. James E. Konklin Office of Inspection and Enforcement U.S. Nuclear Regulatory Commissioa Washington, DC 20555

Subject:

Dresden Station Unit 3 Modification Installation Inspection NRC Docket No. 50-249

Dear Mr. Konklin:

During.your recent Safety System Outage Modification Installation Inspection at Dresden Station, while reviewing safety valve test work requests, several questions were raised by Mr. R. L. Lloyd which were unanswered during your visit. Answers to these questions, as we understand them, are attached.

Should you have any other questions, please contact this office.

]

Very truly yours,

(

• J. R. Wo arowski Nuclear Licensing Administrator i

1m Attachment 2166K 6 8610090380 860929 hi t PDR ADOCK 05000249 (

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PDR

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1. When the safety valves are tested on the steam test boiler, the body temperature in the disc area is seasured. .How does this temperature correspond with the drywell conditions?

ANSWER: The valve being tested"lillacid on the steam test staEd~ aid an

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insulated cover placed over the valve. Per our test procedure.

DNP 200-30, the valve is heated to 200*F. The valve is propped first to resent the disc, then held for 15 minutes at 1000 pai.

Pressure is then increased to 1200 psi and held for one minute.

Then pressure is increated to the pop pressure. This pop is ,

used to make adjustments to the valve. Between each pop, a 15-minute temperature equalization period is required. Additionally, two successive correct pops are required before clearing the valve.

It is believed that in this period of time, the insulated valve ~

components reach an equalibrium temperature.

In 1972, the Station Nuclear Engineering Department conducted a series of tests to measured' drywell temperatures and the affect of temperature on safety valve performance. These tests indicated a drywell temperature of approximately 190 0F. Test results also indicated that if a valve was set " cold", the " hot" pop pressure would be 1% less, i.e. a valve set " cold" on the test boiler at 1260 psi would actually pop at 1247.4 pai,'a' move in the more con-servative direction.  ;

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2. We check only the lift pressure of our safety valves. Why don't we do a reset pressure check of the valve?

ANSWER: We have no requirement to do a reset pressure test. ANSI Perfor- l mance Test code 25.3-1976, Section 4.09(c)(1) Bench Testing states: '

" Bench testing may also be permitted with test stands having limited

accumulator volume and/or pressure source capacity. These tests <

may only be used for determination of the va.1ve set pressure and valve leakage". " Control ring adjustments shall be reset to ori- i ginal test settings". Requirements are contained in DMP 200-30 '

which specify the correct blow-down ring settings, which were ob-tained from Dresser. Our procedure verifies that proper lift pressure is achieved and that the blowdown rings are properly set. i I 3. The calibration sheetc for the pressure gage used to test the safety

, valves were filled out to show the final check to be the same as the i initial check. How can the two set of readings be exactly the same?

ANSWER: The data sheets are designed to accomodate " adjustments" and a re-calibration check, or a before and after set of readings. The gage used in these packages did not require adjustments, so the initial and final readings would be the same. In addition, the source of ,

record for ti.e actual valve pop is the pressure transmitter and strip chart recordet ur.ich is calibrated and not the pressure gage. The pressure gage is used only as an aid to the operator.

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