ML20215F151
| ML20215F151 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/12/1987 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CON-NRC-87-063, CON-NRC-87-63 GL-87-06, GL-87-6, VPNPD-87-241, NUDOCS 8706220261 | |
| Download: ML20215F151 (8) | |
Text
I Wisconsin Electnc eom cowa 231 W. MICHIG AN, P O. BOX 2046 MILWAUKEE,WI 53201 (414)221 2345 VPNPD-87-241 NRC-87-063 i
June 12, 1987 U.
S. NUCLEAR REGULATORY COMMISSION Document Control Desk Washington, D.
C.
20555 Gentlemen:
DOCKETS 50-266 AND 50-301 PERIODIC VERIFICATION OF LEAK-TIGHT INTEGRITY OF PRESSURE ISOLATION VALVES l
(GENERIC LETTER 87-06)
POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Mr. H. R. Denton's letter (Generic Letter 87-06) to all holders of operating licenses dated March 13, 1987, discussed the NRC's concern with the leak-tight integrity of reactor coolant system pressure isolation valves as independent barriers against abnormal leakage, rapidly propagating failure, and gross That letter rupture of the reactor coolant pressure boundary.
directed that we provide the following information pursuant to 10 CFR 50.54(f) within ninety days of the date of the letter.
We understand that Generic Letter 87-06 is requesting information concerning pressure isolating valves in addition to those identified in the Event V program.
The additional valves to be identified include those valves whose failure could cause a loss of coolant accident to other systems whose pressure It l
rating is less than that of the primary coolant system.
does not include instrumentation isolation valves which are small or pressurizer power-operated relief valves and the primary system safety valves which would relieve to the pressurizer relief tank.
j We would like to point out that, in the over thirty years of l
i reactor operation achieved by the two Point Beach units, we to the best of our recollection, experienced leakage have not, l
by any of these valve discs which caused a shutdown or extended We attribute this to the exceptional care we an outage.
exercised in the original specifications, close scrutiny of the vendor during fabrication, rigid acceptance criteria, and l
quality maintenance.
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NRC Document Control Desk June 12, 1987 Page 2 i
Question 1 List all pressure isolation valves at your plant.
Response 1 Listed below are the first and second off valves that provide the interface between the reactor coolant system and systems designed for a lower pressure.
This is in addition to the valves which provide a similar function and are listed in Table 15.3.16-1 of Technical Specifications (attached).
Loop A SI 842A (Second off valve; first off SI 867A listed on Table 15.3.16-1)
Loop B SI 842B (Second off valve; first off SI 867B listed on Table 15.3.16-1)
Residual Heat Removal (Motor-Operated Valves)
Loop B Cold Leg RH 720 (Second off valve; first off SI 867B listed on Table 15.3.16-1)
Loop A Hot Leg RH 700 (First off)
RH 701 (Second off)
Reactor Coolant Loop Drain Valves Loop B (Motor-Operated Valves)
RC 598 (First off)
RC 599 (Second off)
Loop A (Manual Valves)
RC 503 (First off)
RC 541 (Second off)
Question 2 For each valve describe the periodic tests or other measures performed to assure the integrity of the valve as an independent barrier at the reactor coolant pressure boundary.
Also discuss the acceptance criteria for leaking, if any; operational limits, if any; and any frequency of test performance.
NRC Document Control Desk June 12, 1987 Page 3 Response 2 Reactor coolant system leak rate is calculated by the plant process computer system as a normal computer output.
On a daily basis, the leak rate for the reactor coolant system is also manually calculated.
Technical Specification 15.3.1.D requires that reactor coolant leak. rate criteria be met.
It also requires a special safety evaluation if the leak rate is greater than one gpm, as well as the time frame by which the evaluation is to be initiated and the reactor to be shut down if the leak is not found to be safe or the leak rate is greater than 10 gpm.
We believe that these measures have assured, and l
will continue to assure, the integrity of these reactor coolant system pressure isolation valves during unit operation.
Check Valves The check valves listed on Table 15.3.16-1 in'the response to Question 1 are maintained functional and tested in accordance with attached Technical Specifications 15.3.16, " Reactor Coolant System Pressure Isolation Valves," and 15.4.16,
" Reactor Coolant System Pressure Isolation Valves Leakage Tests."
These specifications require that the specified valves be tested each refueling or whenever the unit is in cold shutdown for more than seventy-two hours if testing was not done during the preceding nine months.
They also establish a one gpm leakage limit for check valve testing and, based upon various qualifications from previous test leak rates, allow the limit to be increased up to 5 gpm.
Although no special leak testing is done for check valves 842A and 842B, monitoring of accumulator levels each shift ensures that these valves, in conjunction with their associated first off check valve (which is tested in accordance with Technical Specification 15.4.16), are not leaking.
Also, during monthly testing of the safety injection system, check valves 842A and 842B are pressurized with the safety injection pump such that any leakage through them would be detected as a level change in the safety 4
injection accumulator which has a six-inch level band.
During this test, pressure in the safety injection line is greater than 1500 psig while the accumulator is at 750 psig.
Motor-Operated Valves In addition to the Technical Specification requirements regarding coolant system leakage discussed above, RH-700 and j
701 are tested during the start-up from refueling outages.
No leak rate criteria is specified; however, a qualitative go/no-go criteria based on pressure changes in downstream
4 NRC Document' Control Desk June 12, 1987 Page 4 piping is utilized.
RH-720 cannot be tested ac.
motor-operated valves RH-700 and 701 are tested because check valve SI 867A, a first off pressure isolation valve, prevents pressurization of motor-operated valve RH-720 from the reactor coolant system.
SI 867A is tested in accordance with Technical Specification 15.4.16.
During operation of the reactor coolant system above 425 psi, the valves are closed, and power is removed from the motor operators.
RH-700 and MOV 720 also have a pressure interlock which prevents opening the valves if the reactor coolant system is greater than 425 psig.
RH-701 is in series with RH-700.
No special leak testing is performed on motor-operated valves RC 598 and 599 or manual valves RC 503 and 541.
The reactor coolant drain tank, however, is monitored each shift; therefore, any leakage through the combination of valves would be readily noticeable.
Motor-operated valves RC 598 and 599 are normally closed with power removed from their operators.
If you have any questions, please do not hesitate to contact us.
Very truly yours, c
C.
W.< ay Vice President Nuclear Power Enclosure Copies to NRC Regional Administrator, Region III NRC Resident Inspector Subscribed and sworn to before me this I A Sk day of June, 1987.
AM[$ - W J Notary Public, State 46f Wisconsin My Commission expires
.f-27 7d.
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i 15.3.16 REACTOR COOLANT SYSTEM PRESSURE ISOLATION VALVES Applicability Applies to the operational status of the reactor coolant system pressure isolation valves during power operation, startup and shutdown where reactor coolant temperature is greater than 200 F and shutdown margin is less than 1% AK/K.
Objective To increase the reliability of reactor coolant system pressure isolation valves thereby reducing the potential for an intersystem loss of coolant accident.
Specification A.
Each pressure isolation valve listed in Table 15.3.16-1 shall be functional as a pressure isolation device, except as specified in B.
Valve leakage shall not exceed the amounts indicated.
B.
In the event that the integrity of any pressure isolation valve specified in Table 15.3.16-1 cannot be demonstrated, reactor operation may continue, provided that at least two valves in each high pressure line having a non-functional valve are in, and remain in, the mode corresponding to the isolated condition.(a)
C.
If specifications A and B cannot be met, an orderly shutdown shall be initiated and the reactor shall be in the cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Basis The operational requirements for reactor coolant system pressure isolation valves provide added assurance of valve integrity thereby reducing the probability of gross valve failure and consequent intersystem LOCA which bypasses containment.
(a) Manual valves shall be locked in the closed position; motor operated valves shall be'placed in the closed position and power supplies deenergized.
Unit 1 - Amendment No. 91 15.3.16-1 April 28, 1985 Unit 2 - Amendment No. 95
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TABLE 15.3.16-1 I
REACTOR COOLANT SYSTEM PRESSURE ISOLATION VALVES (a) (b)
System Check Valve No.
j Residual Heat Removal Line 1 853C 853A j
Line 2 853D 853B Safety Injection Loop A Cold Leg 867A 845A 845E Loop B Cold leg 867B 845B 845F R.V. Hot Leg Line A 845C R.V. Hot Leg Line B 845D Footnotes:
(a) 1.
Leakage rates less than or equal to 1.0 gpm are considered acceptable.
2.
Leakage rates greater than 1.0 gpm but less than or equal to 5.0 gpm are considered acceptable if the latest measured rate has not exceeded the rate determined by the previous test by an amount that reduces the margin between measured leakage rate and the maximum permissible rate of 5.0 gpm by 50% or greater.
3.
Leakage rates greater than 1.0 gpm but less than or equal to 5.0 gpm are considered unacceptable if the latest measured rate exceeded the rate determined by the previous test by an amount that reduces the margin between measured leakage rate and the maximum permissible rate of 5.0 gpm by 50% or greater.
4.
Leakage rates greater than 5.0 gpm are considered unacceptable.
(b) Minimum differential test pressure shall not be less than 150 psid.
Unit 1 15.3.16-2 Order dated April 20, 1981 Unit 2
15.4.16 REACTOR COOLANT SYSTEM PRESSURE ISOLATION VALVES LEAKAGE TESTS Applicability Applies to inspection criteria for the reactor coolant system pressure isolation valves.
Objective To provide assurance of the continuing integrity of the reactor coolant system pressure isolation valves.
Specification A.
Periodic leakage testing (a) on each valve listed in Table 15.4.16-1 shall be accomplished every time the plant is placed in the cold shutdown condition for refueling, each time the plant is placed in a cold shutdown condition for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if testing has not been accomplished in the preceding 9 months, and prior to returning the valve to service after maintenance, repair or replacement work is performed.
B.
Whenever integrity of a pressure isolation valve listed in Table 15.4.16-1 cannot be demonstrated, the integrity of the remaining valve in each high pressure line having a leaking valve shall be determined and recorded daily.
In addition, the position of one other valve located in the high pressure piping shall be recorded daily.
Basis l
The surveillance requirements for reactor coolant system pressure isolation I
valves provide added assurance of valve integrity thereby. reducing the probability of gross valve failure and consequent intersystem LOCA which bypasses containment.
I (a) To satisfy ALARA requirements, leakage may be measured indirectly (as from the performance of pressure indicators) if accomplished in accordance with approved procedures and supported by computations showing that the method is capable of demonstrating valve compliance with the leakage criteria.
Unit 1 15.4.16-1 Order dated April 20, 1981 Unit 2
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P TABLE 15.4.16-1 REACTOR COOLANT SYSTEM PRESSURE ISOLATION VALVES (a)(b)
System Check Valve No.
Residual Heat Removal Line 1 853C 853A Line 2 853D 8538 Safety Injection Loop A Cold Leg 867A 845A 845E Loop B Cold Leg 867B 845B 845F R.V. Hot Leg Line A 845C R.V. Hot Leg Line B 8450 Footnotes:
(a) 1.
Leakage rates less than or equal to 1.0 gpm are considered acceptable.
2.
Leakage rates greater than 1.0 gpm but less than or equal to 5.0 gpm are considered acceptable if the latest measured rate has not exceeded the rate determined by the previous test by an amount that reduces the margin between measured leakage rate and the maximum permissible rate of 5.0 gpm by 50% or greater.
3.
Leakage rates greater than 1.0 gpm but less than or equal to 5.0 gpm are considered unacceptable if the latest measured rate exceeded the rate determined by the previous test by an amount that reduces the margin between measured leakage rate and the maximum permissible rate of 5.0 gpm by 50% or greater.
4.
Leakage rates greater than 5.0 gpm are considered unacceptable.
(b) Minimum differential test pressure shall not be less than 150 psid.
1 I
1 1
Unit 1 15.4.16-2 Order dated April 20, 1981 Unit 2 L