ML20009B391
| ML20009B391 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/29/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20009B390 | List: |
| References | |
| NUDOCS 8107150357 | |
| Download: ML20009B391 (3) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO GRANTING OF RELIEF FROM ASME CODE SECTION XI INSERVICE TESTING REQUIREMENTS OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION, UNIT NO: 1 DOCKET NO. 50-285 Introduction By_ letter dated July 9, 1980, as supplemented May 20, 1981, Omaha Public Power District (OPPD, the licensee) requested relief from certain ASME Code Section XI inservice testing requirements.
The relief recuest relates to inservice testing (exercising) of check valves SI-159 and SI-160. These are both Category C valves as defined by Section XI of the ASME Code. For this category of valves, the Code requires that such valves be exercised once every three months unless it is not practical to do so during cower cperation, in which case they should be tested at cold shutdown. The licensee proposes to inspect SI-160 at a refueling outage this fall, and, assuming acceptable results, perform a visual inscection on one valve each five years thereafter on an alternating inspection schedule.
Valve SI-159 was visually inscected during the 1930 refueling outage.
Discussion and Evaluation These check valves, redundant to each other and independent, are physically located in the recirculation piping downstream of the containment and are used to block any direct flow of water from the Safety Injection and Refueling Water Storage Tank to the containment. At least one of these valves must open'to provide for the long-term recirculation of spilled coolant from the containment to the reactor core folloning a LOCA. ASME Code requirements for the inservice testing of these valves were not in existence at the time the plant was desianed and constructed; therefore, no provisions had been made for in-service testing of these valves.
In a letter dated July 2, 1979, the NRC granted interim relief from testing these valves per the ASME Code requirements and agreed with the licensee that with the present piping arrangement it is impractical to do so, since, in order to fully open and exercise these check valves, the containment floor must be filled with water.
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8107150357 810629 PDR ADOCK 05000285 P
! Nevertheless, these valves perform a vital post-LOCA safety function (i.e.
recirculation cooling of the reactor core following a LOCA), and we concluded in our letter granting interim relief of July 2, 1979 that ways should be investigated by the licensee to assure the; operability of these valves.
Prior to granting interim relief, the licensee proposed (Omaha Public Power District letter dated 12/8/78) that one of the following two approaches would be used at the next refueling outage to demonstrate the operability of these valves:
(a) A modification would be performed to permit periodic flow testing of these valves, or (b) SI-159 would be removed, inspected and tested. The results of this inspection would be used to determine the need for inspecting SI-160 and the need for further inspections.
The results of the inspection / test were to be submitted to the staff for review, along with recomrcendations for future inspection and testing as deemed appropriate.
On February 13, 1980,51-159 was removed frcm the piping system for visual and functional examination, and found to be in "like new" concition. 0???
tc0k chotograchs of the valve in the as-found conditicn as further evidence of the valve's concition.
These were suomitted with the CPPD July 9, 1930 letter.
We agree with the licensee that SI-159 was found in excellent and functional condition.
The valve has not been inspected since the plant began operation in 1973, and therefore, the valve has been in place for about seven years with no degradation observed. The valve was examined internally for signs of degradation due to damage, buildup of foreign material, missing parts, and checked for freedom of movement by hand. The valve was found to be completely acceptable on all counts, and returned to service without need for any maintenance.
The licensee's proposal to inspect SI-160 at the next refueling outage (fall 1981) is acceptable. Our acceptance of this alternative examination to the Code requirement is based on the following:
1.
The valve in the other safety train, SI-159, was inspected and found in "like new" condition after seven years of service.
2.
The valves consist of two semicircular plates, h1nged along the diameter. The design is such that the two halves of the valve operate independently of each other. Therefore, a failure of one of the oiscs to open would not, by itself, prevent the other oisc from opening. Either oisc when open will pass sufficient flow for core cooling.
. 3.
The valves are in redundant lines.
If either check valve fails to open (both discs) in the recirculation mode, there would be sufficient flow through the other line to provide for core cooling.
Based on the foregoing, we conclude, pursuant to 10 CFRf 50.55a(gX6)(1),
that granting of this relief is authorized by law and will not endanger life or property, or the common defense and security, and is otherwise f a the public interest.
In making this determination, we have given due consideration to the burden that would result if the Code requirements were imposed on the facility, and conclude that relief should be granted.
This relief is conditioned on the following:
1.
Th'at the licensee visually inspect SI-160 at the next refueling outage.
2.
That the inspection be conducted in a manner similar to that performed on SI-159.
3.
That the results of the inspection be reported to HRC within 30 days after the inspection, and include color photographs of the valve "as found".
If ne inspection results are acceptable, the relief shall continue until the end of the 10-year inspection interval which enas en September 26, 1953.
Althcugh the licensee has prcocsed to initiate a five-year alternating inspection schedule en these two valves, we need net reach :nis cuestien at this point since this relief expires on Septemoer 26, 1953, before this program would begin.
Since this (and all other) relief expires on this date, the licensee will have to consider anew any relief when the next 10-year inservice testing program is developed.
Date: JUN 211981 4