2CAN078211, Responds to NRC 810929 Request for Info Re NUREG-0737,Item II.D.1, Pressurizer Safety/Relief Valve Operability. Pressurizer Safety Valves Function as Predicted Under All Credible Operating & Accident Conditions in FSAR

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Responds to NRC 810929 Request for Info Re NUREG-0737,Item II.D.1, Pressurizer Safety/Relief Valve Operability. Pressurizer Safety Valves Function as Predicted Under All Credible Operating & Accident Conditions in FSAR
ML20062D928
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 07/28/1982
From: John Marshall
ARKANSAS POWER & LIGHT CO.
To: Clark R
Office of Nuclear Reactor Regulation
References
RTR-NUREG-0737, RTR-NUREG-737, TASK-2.D.1, TASK-TM 2CAN078211, 2CAN78211, NUDOCS 8208060266
Download: ML20062D928 (3)


Text

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ARKANSAS POWER & LIGHT COMPANY POST OFRCE BOX 551 LITTLE ROCK. ARKANSAS 72203 (501)371-4000 July 28, 1982 2CAN078211 Director of Nuclear Reactor Regulation ATTN: Mr. Robert A. Clark, Chief Operating Reactors Branch #3 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555

SUBJECT:

Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6 NUREG-0737, Item II.D.1 Pressurizer Safety / Relief Valve Operability Gentlemen:

Pursuant to NUREG-0737, Item II.D.1 and your letter of September 29, 1981,(0CNA108105) Arkansas Power and Light is providing the following response to that request for submittal.

Item II.D.1.A of NUREG-0737 required that utilities operating and/or constructing Pressurized Water Reactor (PWR) power plants provide evidence supported by test, of safety and relief valve functionability.

In response to these requirements, the Electric Power Research Institute (EPRI) implemented a generic test program on behalf of the PWR utilities.

j Arkansas Power and Light has been a participant in the EPRI program. The NRC Generic Letter 81-36 dated September 29, 1981, contains a schedule for submittal of test results and plant-specific reports. The following documents were transmitted to you on April 1,1982, by Mr. David Hoffman of Consumers Power Company on behalf of the PWR util: ties participating in the EPRI studies and are incorporated herein by references as part of this submittal.

o PWR Safety and Relief Valve Test Program Valve Selection / Justification Report i EPRI NP-2292-LD, April 1982 1

o Valve Inlet Ficid Conditions for Pressurizer Safety and Relief Valves in Combustion Engineering-Designed Plants EPRI NP-2318-LD, April 1982 OY B208060266 820728 PDR ADOCK 05000368 P PDR MEMBER MIDOLE SOUTH UTIUTIES SYSTEM

, Mr. Robert A. Clark July 28, 1982 .

o EPRI/PWR Safety and Relief Valve Test Program Test Condition Justification Report April 1982 o EPRI/PWR Safety and Relief Valve Test Program Safety and Relief Valve Test Report April 1982 An itemized treatment of the individual requirements of NUREG-0737, II.D.1 for Arkansas Power One-Unit 2 (ANO-2) follows.

1. Item II.D.1.A(1)

The EPRI Safety and Relief Valve Test Report referenced above provides data which show the ability of PWR pressurizer safety valves to open and close under all operating and accident conditions as analyzed in the AN0-2 Final Safety Analysis Report (FSAR). It is our judgement that the tests performed provide substantial data to document the successful performance of valves representative of those installed at AN0-2. This judgement is based on an evaluation of the remaining items of NUREG-0737, Item II.D.1.A.

2. Item II.D.1.A(2)

The valves selected by EPRI and the test conditions established directly represent the design and predicted performance of the valves installed on ANO-2 based on the following:

a. One of the applicable valves tested, the Crosby Valve & Gage Model HB-BP-86, Size 6M6, directly represents the safety valves installed at AN0-2. There are no data to predict significant differences in the operations of the AN0-2 valves under similar conditions.
b. The short inlet piping modeled by the EPRI tests adeq ately represents the ANO-2 installation. Actually, the safety' valves are installed on ANO-2 in a more conservative manner than modeled in the tests, i.e., the ANO-2 valves are installed on a flange mounted on the pressurizer, thus having a much shorter inlet. pipe than modeled.
c. Inlet fluid conditions established for the EPRI tests are comparable or more conservative than the conditions presented in the referenced report, " Valve Inlet Fluid Conditions for Pressurizer Safety and Relief Valves in Combustion Engineering-Designed Plants".
d. The backpressure effects on operability of as-built safety valve discharge piping are judged to be minimal and will not significantly affect the performance of these valves.

Mr. Robert A. Clark .' July 28, 1982

e. Although there is no safety concern, future safety valve adjustments may be beneficial to assure optimal performance.

We are continuing to evaluate the EPRI data to determine if valve adjustments are necessary at ANO-2. In addition, input from the valve manufacturers is being requested and will be incorporated in the evaluation. If results of the evaluation i.idicate the adjustments are necessary, the settings will be altered accordingly,

f. Power operated relief valves are not installed on the ANO-2 facility, and such valves were not factored into operation or transient analyses.

, 3. Item II.D.1.A(3)

The test data are provided in the aforementioned FPRI " Safety and Relief Valve Test Report" for safety valve operation.

Data from the EPRI tests have been used to benchmark a computer program which models the discharge piping and predicts the forces generated by changes in momentum of the fluid discharged. This program is currently being used to model ANO-2 discharge piping.

Loads resulting from these. forces will be combined with thermal and deadweight loads to allow an evaluation of the adequacy of the existing piping system. The study should be complete by early October 1982, and if so, will be transmitted to you in November 1982. The delay in this area is a result of the EPRI data needed to benchmark the program being submitted behind schedule.

4. Item II.D.1.B Analyses performed by each PWR NSSS vendor have shown that isolation of a stuck open power operated relief valve is not required to ensure safe shutdown, and is therefore not a safety issue. In any instance, ANO-2 is not fitted with power operated relief valves;.

therefore, isolating block valves are not applicable to this issue.

Based on our evaluation of the EPRI test results as applied to AN0-2 plant-specific conditions, it is concluded that the pressurizer safety valves function as predicted under all credible operating and accident conditions analyzed in the FSAR. It is our judgement that continued operation with existing pressurizer safety valves will not adversely affect operation or transient mitigation as described in the ANO-2 FSAR and attendant documentation.

Very truly yours, John R. Marshall Manager, Licensing JRM:JC:sc Y