ML20003H185
| ML20003H185 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 04/30/1981 |
| From: | CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | |
| Shared Package | |
| ML20003H181 | List: |
| References | |
| TASK-03-07.D, TASK-3-7.D, TASK-RR NUDOCS 8105050290 | |
| Download: ML20003H185 (4) | |
Text
Docket No. 50-213 Safety Assessment Report SEP Topic 111-7.D, Containment Structural Integrity Tests i
April,1981 8105050 190 J
1 i
Haddam Neck Plant SEP Safety Assessnent Report Topic lll-7.D - Containment Structural Integrity Tests 1.0 Introduction The objective of this topic is to assure that the design and constructive methods provide a structure which will safely perform its intended functions.
This assessment reviews the structural integrity testing procedure to assure that the containment structure vill respond satisfactorily to the postulated design basis loads.
2.0 Criteria Regulatory Guide 1.18 states that:
Concrete primary reactor containments should be subjected to an acceptance test that increases the containment's internal pressure in four or more approximately equal pressure increments from atmospheric pressure to at least 1.15 times the containment design pressure. The containment should be depressurized in the same number of increments.
Measurements should be recorded at atmospheric pressures and at each pressure level of the pressurization and depressurization cycles. At each level, the pressure should be held constant for at least one hour before the deflections and strains are recorded. Crack patterns should be recorded at atmospheric pressure both before and immediately after the test and at the maximum pressure level achieved during the test.
- and, The environmental conditions under which the test may be conducted should be specified. The test should not be conducted under extreme weather conditions, such as snow, heavy rain, or strong vind.
Additional criteria used as a measure of containment structural per-fonnance during and after the test are as follows:
1.
The maximum vertical elongation of the structure shall not exceed 1.2 inches.
2.
The increase in containment diameter shall not exceed 1.3 inches.
3.
The maximum concrete crack vidth shall not exceed 1/32 inch.
4.
When containment pressure is reduced to atmospheric, the width of any cracks which have developed in the concrete during the test shall not exceed.010 inch.
5 There shall be no visual distortion of the liner plate.
3.0 Discussion The containment structural integrity test for Connecticut Yankee was based on the original calculated design pressure of 40 psig. This value, which was recently confirmed to be appropriate as documented in Reference (3), will be reviewed under SEP Topic VI-3 to assure its adequacy.
The containment structure consists of a 121.5 foot high by 135 foot inside diameter cylindrical vall, 4.5 feet thick, with a henispherical dome of 2.5 foot thickness and a 9 foot thick circular mat with a depressed pocket in the center of the mat for the reactor vessel. The bottom of the cylindrical vall and top of the circular mat is approximately 21.5 feet below the ground surface. The inside surface of the containment structural concrete is lined with a steel plate of 1.4 inch thickness across the top of the mat, 3/8 inch thickness inside the cylindrical vall, and 1/2 inch thickness inside the hemispherical dome. The concrete circular mat and the depressed area in the center of the mat are founded upon a granite gneiss rock foundation. A 23 foot disseter access hatch is located in the cylin-drical vall at ground grade. Penetrations for piping and electrical lines are also located in the cylindrical vall.
The containment structure was pressurized with compressed air to a maximum value of 46 psig corresponding to a factor of 1.15 times the design pressure.
TVo weeks before the containment structure was pressurized, the exterior surfaces of the containment cylindrical vall and do=e were carefully examined for cracking.
Cracks observed were recorded for future reference but were of such minor nature as to be considered insignificant. The maxiuum recorded crack vidth (at h0 psig) was 0.01 inches (less than the 1/32 inch allowed). The maximum crack vidth when the pressure returned to atmospheric was 0.001 inches (less than the 0.010 inches allowed).
During the period when the pressure was held at 40 psig an intensive search of those areas which are accessible by foot was made for cracks. It is possible to inspect areas within the pipe and electrical penetration vaults, the area at the steam and feed line penetration platforms and the area of the dose and of the cylinder adjacent to the access ladder and platforms.
Areas at four points on the circumference of the containment were inspected for the complete height of the cylindrical vall by use of a boatswain's chair, covering approximately 10 feet on each side of the chair. The dome was inspected over approximately 40 percent of the done area by use of cables and straps. Thcae areas otherwise inaccessible were inspected by the use of transits located on the ground at various locations around the structure.
Changes in contaicnent dianeter and height were measured by means of engineer's scales attached to brackets positioned along the vertical cylin-drical vall on the north and south sides of the contein=ent and at the top of the dome. The exterior surface of the containment vall at ground grade was checked for out-of-round prior to the pressurization, at h0 psig pressure and subsequent to returning to atmospheric pressure. The variation from
vertical of the cylindrical vall was checked at four locations around the circumference of the container both at 40 psig pressure and subsequent to returning to atmospheric pressure. Ten strain rosettes were located at various points on the containment liner plate. Six of these were in the bmnediate vicinity of the equipment hateh. Ten linear variable differential transducers were located around the hatch opening, 48 similar devices were located vertically along the containment vall, in two lines, starting at the juncture of the mat in two deep pit locations. These were employed to measure radial movements of the lower portion of the containment vall.
Radial changes of the inside surfaces of the containment vall were recorded be measurements taken before and after the test at the polar crane rail.
The maximum vertical elongation of the containment structure was recorded as 1/2 inch at 40 psig. Upon returning the containment pressure to atmospheric, there was no measureable change in the original dimension. The maximum in-crease on containment diameter was recorded as 1-1/4 inches. This occurred at approximately mid height of the cylindrical vall from ground level. Upon returning the containment pressure to atmospheric, the residual change in position of the gauges were 1/4 inch on the south side of the containment and 1/8 inch on the north side of the containment. The maximum recorded crack vidth did not exceed 0.01 inch. Following return of containment pressure to atmorpheric, an inspection of the containment structure revealed no cracks exceeding 0.001 inch. Inspection of the containment liner plate subsequent to returning the containment pressure to atmospheric indicated no visual distortion of the plate.
The following deviations froim current review criteria have been noted:
Current criteria require that the containment's internal pressure be increased in four or more approximate equal pressure increments and de-pressurized in the same number of increments. At each level, the pressure should be held constant for at least one hour before the deflections and strains are recorded. The containment structure was pressurized directly to 46 psig in a period from May 12, 1967 to May 15, 1967 The pressure was maintained at this upper level for at least one hour and was lowered to 40 psig and held for three days. The pressure was lowered to 15 psig held for 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />, and lowered to atmospheric pressure.
Environmental conditions were not recorded to the extent required by current criteria.
Associated SEP Topics o lll-T.B Design Codes, Criteria, Load Combinations o Vl-3 Containment Pressure and Heat Removal Capability 4.0 Conclusions The deviations identified above are not significant and do not affect the conclusions made as a result of the test. The stress in the steel i
h-reinforcement corresponding in the criteria limits stated above'is approximately 19,000 psi compared to a minimum yield strength of 50,000 psi. By maintaining the test criteria, the resulting stresses from this test did not exceed the original design criteria. The adequacy of this criterion will be addressed under SEP Topic lil-7.B.
The test results demonstrated compliance with the established test criteria. Pending resolution of SEP Tbpic VI-3, CYAPC0 concludes that the containment structural integrity test performed assures that the.
containment structure will withstand the design pressure load of 40 psig.
5.0 References 1.
Regulatory Guide 1.18, Structural Acceptance Test for Concrete Primary Reactor Containments.
2.
Standard Review Plan Section 3.8.1, concrete Containment.
3 W. G. Counsil letter to D. M. Crutchfield, dated April 1,1981 4.
D. M. Crutchfield letter to D. L. White, dated May 8, 1980.
.