ML19312D408
| ML19312D408 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 03/21/1980 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8003240351 | |
| Download: ML19312D408 (5) | |
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f o.n.,.i onico.1 via w... ui. nia.n 4..no...,.u.on, uics,a.n 4920,. 4,.. cou, air 7ru..oono March 21, 1980 Director, Nuclear Reactor Regulation Att Mr Dennis L Ziemann, Chief Operating Reactors Branch No 2 US Nuclear Regulatory Commission Washington, DC 20555 DOCKET 50-155 - LICENSE DPR HIG ROCK POINT PLANT - CONSUMERS POWER C0tiPANY RESPONSE TO NRC LETTER DATED FEBRUARY 23, 1980: LVR PRIMARY COOLANT SYSTEM PRESSURE ISOLATION VALVE 3 By letter dated February 23, 1980, the NRC raised concerns regarding pressure boundaries between the Primary Coolant System and low-pressure systems such as the Low-Pressure Injection Systems. This concern revolved around a design configuration involving two in-series check valves isolating the high pressure Primary Coolant System from low pressure systems. This configuration was identified in the WASil-1400 Reactor Safety Study as a significant contributor to possible intersystem Loss of Coolant Accidents. This event would be initiated by the failure of the check valves to function as pressure isolation barriers, thus causing an overpressurization and rupture of low-pressure piping and an eventual LOCA that possibly bypasses containment.
As a result of these concerns, Consumers Power Company was requested to provide the following information:
Item 1 3cscribe the valve configuration at. your plant and indicate if an Event V isolation valve configuration exists within the Class I boundary of the high-pressure piping connecting PCS piping to low pressure system piping; eg, (1) two' check valves in series, or (2) two check valves in series with an MOV.
Response to Item 1 The Event V valve configuration described does not exist at the Big Rock Point Plant on any of the high-pressure piping systems connected to the Primary Coolant System. ine attached Figure 1 shows the piping arrangements for the Emergency Core Spray and Redundant Core Spray Systems.
Both of these systems
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isolate the low pressure Fire Water System from the high-pressure Primary Coolant System using two motor-operated isolation valves and a check valve in series. The motor-operated valves on both of these systems are individually stroked during a monthly surveillance test at which time the Fire Water System pressure is continuously monitored for evidence of any pressure increase due to Primary Coolant System pressure leakage past.the check valve and _ the other motor-operated isolation valve.
Two other high-pressure piping systems at Big Rock Point provide Prinary Coolant System isolation using more than two check valves in series and, thus, do not classify as an Event V valve configuration. These two systems are the Feedwater System (Figure 2) and the Control Rod Drive Hydraulic Gystem (Figure 3).
The Feedwater System isolates the low-pressure Condensate System from the high pressure Primary Coolant System using three check valves and an air-operated regulating valve in series. The Control Rod Drive Hydraulic System isolates the low pressure suction piping from the high pressure Primary Coolant System using a minimum of four check valves (two are internal to the CRD pumps).
Item 2 If either of the above Event V configurations exist at your facilitv. indicate whether continuous surveillance or periodic tests are being accomplished on such valves to ensure integrity. Also indicate'whether valves have been knovn,'or found, to lack integrity.
Response to Item 2 The Event V valve configuration described does not exist at the Big Rock Point Plant.
Item 3 If either of the above Event V configurations exist at your facility, indicate whether plant procedures should be revised or if plant modifications should be made to increase reliability.
Response to Item 3 The Event V valve configuration described does not exist at the Big Rock Point Plant.
j David P Hoffman (Signed)
David P Hoffman
-Nuclear Licensing Administrator CC JGKeppler, USNRC i
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a FIGURE I EMERGENCY CORE SPRAY AND REDUNDANT CORE SPRAY SYSTEMS I
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DEDS C4: MATERIAL SS 304 PRIMARY RATING 1500 psig e 10000 F E-lI: MATERIAL CARBON STEEL PRIMARY RATING 150 psig e 5000 F A-7: MATERIAL CARBON STEEL PRIMARY RATING 1500 psig e 8SO F
FIGURE 2 REACTOR FEEDWATER SYSTEM CAPPED CON TAI NMEN T SNUT-Down PENETRATION FLUSNING LINE STEAM h
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l B-2: SAME AS 8-l D-3: MATERI AL-CARBON STEEL FRIMARY RATlMG -300 psig a 8500 F
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