ML19294A415

Response to Requests for Info Re Insvc Testing & Inspec of Check Valves in the Safety Injection Recirculation Lines at Subj Facil

ML19294A415
Person / Time
Site:	Fort Calhoun
Issue date:	11/03/1978
From:	Short T OMAHA PUBLIC POWER DISTRICT
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 7811130184
Download: ML19294A415 (5)

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Omaha Public Power District

"~z/l-1623 HARNEY s OMAHA, NEBRASKA 68102 e TELEPHONE 536-4000 AREA CODE 402 November 3, 1978 Director of Nuclear Reactor Regulation ATTN: Mr. Robert W. Reid, Chief Operating Reactors Branch No. 4 U. S. Nuclear Regulatory' Commission Washington, D. C. 20555

Reference:

Docket No. 50-285 Gentlemen:

The Omaha Public Power District received a request for specific information in regard to inservice testing and inspection of check valves in the safe +y injection recirculation lines at the Fort Cal-houn Station. Accordingly, responses to that request are attached.

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Sincerely,

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S 3r.

Divisio Manager Production Operations TES/KJM/BJH: jam Attach.

cc: LeBoeuf, Lamb, Leiby & MacRae 1757 "N" Street, N. W.

Washington, D. C. 20036 7811130(84 0\

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Question 1 Is the containment side of these check valves normally exposed to water or air?

Response

The containment side of the check valves is normally esposed to some water.

Question 2 What is the function of the test connections between the check valves and containment vall?

Resrnnse The one inch test lines between the check valves and the containment vall are used to pressurize the safety injection recirculation lines up-stream of containment isolation valves HCV-383-3 and HCV-383 h. These containment isolation valves must be leak tested at periodic intervals in accordance with 10 CFR Part 50, Appendix J.

Question 3 What is the maximum expected boron concentration in the refueling water / safety injection tank?

Response

Shutdown boron concentration for Cycle 5 operation is specified to be greater than 1700 ppm. It is not anticipated that baron concentration in the safety injection and refueling water storage tank would exceed 2200 ppm.

Question h_

Are these check valves accessible for maintenance during all plant operating modes?

Response

These check valves are located in Room 23 of the auxiliary building.

This room is accessible during all modes of operation. However, these check valves are not accessible for maintenance during all modes of opera-tion. This is because performing maintenance on the valves would render a portion of the emergency core cooling system inoperable. When the re-actor is critical, the ECCS is required to be operable within the limit-ing conditions for operation specified in Section 2.3 of the Fort Calhoun Technical Specifications.

Question 5 What temperature ranges are these check valves exposed to during normal summer and vinter temperatures? Would high AP be required to open these valves during vinter vs. summer months?

Response

During normal vinter and summer months, these check valves vould be exposed to ambient air temperatures ranging from 600F to 1000F. It is not expected that a higher AP vould be required to open these valves during vinter vs. summer nonths, since tne seasonal temperature variation is ex-tremely small.

Question 6 When and how was the initial check valve full flow test performed with the valves installed? What AP van used during the preop. test?

Did valve go full open?

Response

A full flow test has not been performed subsequent to installation of the check valves. The physical configuration of the inlet to the containment recirculation line places practical limitations upon the performance of such a test. This subject is discussed more thoroughly in the response to Question 10.

Question 7 How many man-hours vould be involved in removing, bench testing, and replacing each valve? What specific plant conditions would be re-quired to bench test one valve at a time? State the sp 'ific technica' reasons as to why these check valves cannot be bench tested during eaci cold shutdown or refueling outage. Is there a radiation hazard involved during removal of these check valves? If a radiation hazard is present ,

state the source and the nr/hr involved. What proof test would be re-quired after you reinstall the valve into the line?

Re.ponse It is estimated that 30 man-hours would be expended to remove, bench test, and replace each valve. In order to perform such testing, the en-tire safety injection header associated with the valve vould have to be drained, thus causing a major part of the emergency safeguard system to be rendered inoperable. Realistically, this could only be accomplished during a refueling outage, in view of the degree of inoperability of the ECCS and the time required to perform the test. It is not deemed practi-cal to bench test these valves during a refueling outage for the follow-ing reasons:

(1) Draining the entire safety injection header would cause an ex-treme load on the vaste water treatment system.

(2) Dropping the 2h inch check valve out of the recirculation line vould require the use of an overhead crane. _ No overhead crane is presently located in the area.

(3) Periodic removal and testing of these valves may jeopardize the integrity of the bolts, flanges, and seals.

During removal of these valves, it is expected that workers would be exposed to a certain amount of radioactive water from the recirculation header, resulting in a potential contamination problem. The general area where the valves are located is a radiation area with radiation levels ranging from 6 to 20 mrem /hr. It is not anticinated that any specific proof test would be required after the installation of the valves into the line.

Question 8 Have any alternate tests been considered to partial stroke test these check valves?

Response

The physical construction of the valve does not allow access to the disc for mechanical stroking. Therefore, no alternate test is possible.

Q_uestion 9 How long have these check valves been installed in the system and not tested while being exposed to normal operating and shutdown conditions?

If these valves were removed for bench testing, could a determination be made on the rate of foreign matter build-up, and a time span determined for the periodic removal, inspection, and bench testing of these valves?

Response

/ ort Calhoun Station tiit No. 1 was placed in commercial operation in September of 1973. Check valves SI-159 and SI-160 ha-e not been tested since that time. Removal of the valves would allow inspection for foreign matter build-up; however, it is probable that this inspection would be in the form of subjective observation rather than objective measuremen t. The initial inspection would allow the rate of foreign matter build-up to be estimated based upon the length of time for which the valves have thus far been in service. It should be emphasized, however, that the District considers such an inspection program to be undesirable, as discussed in the response to Question 7 Question 10 How often are the full flow tests of the HPSI, LPSI, and CS systems performed? Why can't the sump be filled and a suction taken from it for one of the above full flow tests?

Response

Full flow tests are performed on the HPSI, LPSI, and CS systems every refueling outage. It is not practical to full flow test these valves because to do so would require flooding of the containment base-ment, thus resulting in the potential for significant damage to electrical equipment and corrosive materials. In addition, it is impractical to handle and treat the waste generated by such a test. It must be emphasi'ed that the suction of the recirculation headers is not taken from a contain-ment sump, but is actually taken from the basement floor of the contain-ment.

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Question 11 What is the distance between the suction strainers? What types of foreign matter could these strainers and check valves be exposed to? Are these suction strainers located in a sump or at floor level?

Response

The suction straincrs are separated by a distance of approximately 6 feet, center-to-center. The strainers and check valves could be ex-posed to various types of dirt and debris which would normally be found on the containment floor, plus demineralized water which is occasionally used to vash down the floor. It should be emphasized that, inasmuch as the containment is a radiologically controlled area, the floor is nor-mally kept very clean. The District considers the possibility of signi-ficant foreign matter falling in the strainer to be very lov. In addi-tion, containment isolation valves HCV-383-3 and HCV-383 h upstream of the check valves are closed, except during testing, thus preventing the entrance of foreign matter from the containment. The size of this debris would be limited to material which would pass through 1/h" vire mesh.

The strainers are located 1-1/2" above the finished floor at the basement level of containment, clevation 99h'-0". The strainers are not installed in a sump of any type.

Question 12 What is the normal differential pressure across these check valves?

What is the normal differer.tial pressure expected across these valves during a LOCA as compared to what the differential pressure the manu-facturer specifies is needed to open these valves?

Response

Since these check valves are exposed to air on the containment side, the normal differential pressure is approximately 9.8 psi acting to close the valves. The mininum differential pressure expected across these valves during a LOCA, acting in a direction to open the valves, is 6.2 psi. The differential pressure required to open the valves, as stated by the manufacturer, is .16 psi.

Question 13 If there is a significant radiation field that these valves are ex-posed to, what extent would this field effect any of the parts of the valve?

Response

The radiation field the valves are exposed to is primarily made up of beta and gamma activity. Since the valves are of metallic construction, it is not expected that the radiation field would effect any of the parts of the valve. Significant radiation effects on metals are generally asco-ciated with neutrons and heavy charged particles. As reported in response to Question 7, t'ae general area where these valves are located is a radiation area with radiation levels ranging from 6 to 20 mrem /hr.