ML20045H717

Proposed Tech Specs Supporting Drywell Pressure/Temp Change

ML20045H717
Person / Time
Site:	Oyster Creek
Issue date:	07/12/1993
From:	GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20045H715	List: ML20045H714 ML20045H716 ML20045H717
References
NUDOCS 9307210174
Download: ML20045H717 (6)

Text

.. . . ._ _- . _ _ . .

l r .I l

. .j;',. ,

0YSTER CREEK TECHNICAL SPECIFICATION CHANGE RE0 VEST NO. 198 REV. 1 b

REVISED TECHNICAL SPECIFICATION PAGES t

9307210174 930712 PDR

.P ADOCK 05000219 y

?DR g

)

., s . . l The containment spray' system is provided to remove heat energy from the  !

containment in the event of a loss-of-coolant accident. Actuation of the  !

containment spray system in accordance with plant- emergency operating procedures ensures that containment and torus pressure and temperature I conditions are within the design basis for containment integrity,.EQ, and core  !

spray NPSH requirements. The flow from one pump in either loop is more than 1 ample to provide the required heat removal capability (2). The emergency service water system provides cooling to the containment spray heat exchangers and, therefore, is required to provide the ultimate heat sink for the energy release in the event of a loss-of-coolant accident. The emergency service water pumping requirements are those which correspond to containment cooling heat exchanger performance implicit in the containment cooling description.

Since the loss-of-coolant accident while in the cold shutdown condition would not require containment spray, the system may be deactivated to permit integrated leak rate testing of the primary containment while the reactor is in the cold shutdown condition.

The control rod drive hydraulic system can provide high pressure coolant injection capability. For break sizes up to 0.002 ft , a single control rod drive pump with a flow of 110 gpm is adequate for maintaining the water level nearly five feet above the core, thus alleviating the necessity for auto-relief actuation (3).

The core spray main pump compartments and containment spray pump compartments were provided with water-tight doors (4). Specification 3.4.E ensures that the doors are in place to perform their intended function.

Similarly, since a loss-of-coolant accident when primary containment integrity is not required would not result in pressure build-up in the drywell or torus, the containment spray system may be made inoperable under these conditions.

References

1. NEDC-31462P, "0yster Creek Nuclear Generating Station SAFER /COREC00L/GESTR-LOCA Loss-of-Coolant Accident Analysis,"

August 1987.

2. Licensing Application, Amendment 32, Question 3

3. Licensing Application, Amendment 18, Question 1

4. Licensing Application, Amendment 18, Question 4

5. GPUN Topical Report 053, " Thermal Limits with One Core Spray Sparger" l December 1988. I l

6. NEDE-30010A, " Performance Evaluation of the Oyster Creek Core Spray Sparger", January 1984.

7. Letter and enclosed Safety Evaluation, Walter A. Paulson (NRC) to P. B.

Fiedler (GPUN), July 20, 1984.

8. APED-5736, " Guidelines for Determining Safe Test Intervals and Repair Times for Engineered Safeguards", April 1969.

0YSTER CREEK 3.4-8 Amendment No.: 153,160

., A * ,

rod worth such that a rod drop would not result in any fuel damage. In addition, in the unlikely event that an excursion did occur, the reactor

' +

building and standby gas treatment system, which shall be operational during this time, offer a sufficient barrier to keep off-site doses well below 10 CFR 100 limits.

The absorption chamber water volume provides the heat sink for the reactor coolant system energy released following the loss-of-coolant accident.

The core spray pumps and containment spray pumps are located in the corner rooms and due to their proximity to the torus,.the ambient temperature in those rooms could rise during the design basis accident. Calculations (7) made, assuming an initial torus water temperature of 100 F and a minimum water volume of 82,000 ft3, indicate that the corner room ambient temper-ature would not exceed the core spray and containment spray pump motor operating temperature limits and, therefore, would not adversely affect the long-term core cooling capability. The maximum water volume limit allows for an operating range without significantly affecting accident analyses with respect to free air volume in the absorption chamber. For example, 3the containment capability (8) with a maximum water volume of 92,000 ft is reduced by not more than 5.5% metal-water reaction below the capability with 82,000 ft . 3 Experimental data indicate that excessive steam condensing loads can be avoided if the peak temperature of the suppression pool is maintained below 160 F during any period of relief valve operation with sonic conditions at the discharge exit. Specifications have been placed on the envelope of reactor operating conditions so that the reactor can be depressurized in a timely manner to avoid the regime of potentially high suppression chamber loadings.

The technical specifications allow for torus repair work or inspections that might require draining of the suppression pool when all irradiated fuel is removed or when the potential for draining the reactor vessel has been minimized. This specification also provides assurance that the irradiated fuel has an adequate cooling water supply for normal and emergency conditions with the reactor mode switch in shutdown or refuel whenever the suppression pool is drained for inspection or repair.

The purpose of the vacuum relief valves is to equalize the pressure between the drywell and suppression chamber, and suppression chamber and reactor building so that the containment external design pressure limits are not exceeded.

The vacuum relief system from the reactor building to the pressure suppression chamber consists of two 100% vacuum relief breaker subsystems (2 parallel sets of 2 valves in series). Operation of either subsystem will maintain the containment external pressure less than the 2 psi external design pressure of the drywell; the external ' design pressure of the suppression chamber is 1 psi (FDSAR Amendment 15. Section 11).

The capacity of the 14 suppression chamber to drywell vacuum relief valves is sized to limit the external pressure of the drywell during post-accident drywell cooling operations to the design limit of OYSTER CREEK 3.5-8 Amendment No.: 75

4-wJ --

Basis: In the event of a loss-of-coolant accident, the peak drywell pressure

• would be 38 psig which would rapidly reduce to 20 psig within 100 seconds following the pipe break. The total time the drywell pressure would be above 35 psig is calculated to be about 7 seconds.

Following the pipe break, absorption chamber pressure rises to 20 psig within 8 seconds, equalizes with drywell pressure at 25 psig within 60 secog and thereafter rapidly decays with the drywell pressure decay.

The design pressures of the drgell and absorption chamber are 62 psig and 35 psig, respectively. The original ca peak drywell pressure was subsequently reconfirmed.gulated 38 psig A 15% margin was applied to revise the drywell design pressure to 44 psig. The design leak rate is 0.5%/ day at a pressure of 35 psig. As pointed out above, the pressure response of the drywell and absorption chamber following an acciJent would be the same after about 60 seconds. Based on the calculated primary containment pressure response discussed above and the absorption chamber design pressure, primary containment pre-operational test pressures were chosen.

Also, based on the primary containment pressure response and the fact that the drywell and absorption chamber function as a unit, the primary containment will be tested as a unit rather than testing the individual components separately.

The design basis loss-of-coolant accident was evaluated at the primary containment maximum allowable accident leak rate of 1.0%/ day at 35 psig. The analysis showed that with this leak rate and a standby gas treatment system filter efficiency of 90 percent for halogens, 95% for particulates, and assuming the fission product  ;

release fractions stated in TID-14844, the maximum total whole body passing cloud dose is about 10 rem and the maximum total thyroid dose '

is about 139 rem at the site boundary considering fumigation conditions over an exposure duration of'two hours. The resultant doses that would occur for the duration of the accident at the low population distance of 2 miles are lower than those stated due to the variability of meteorological conditions that would be expected to occur over a 30-day period. Thus, the doses reported are the maximum that would be expected in the unlikely event of a design basis loss-of-coolant accident. These doses are also based on the assumption of no holdup in the secondary containment resulting in a direct release of fission product from the primary containment through the filters and stack to the environs. Therefore, the specified primary containment leak rate and filter efficiency are conservative and provide margin between expected offsite doses and 10 CFR 100 guideline limits.

Although the dose calculations suggest that the allowable test leak rate could be allowed to increase to about 2.0%/ day before the guideline thyroid dose limit given in 10 CFR 100 would be exceeded, '

establishing the limit of 1.0%/ day provides an adequate margin of safety to assure the health and safety of the general public. It s further considered that the allowable leak rate should nut deviate significantly from the containment design value to take advantage of the design leak-tightness capatslity of the structure over its service lifetime. Additional margin to maintain the containment in Change: 7, 27.

0YSTER CREEK 4.5-12 Amendment No.: 132 I

..g P :. . ,

The drywell exterior was coated with Firebar D prior to concrete i pouring during construction. The Firebar D separated the drywell

- steel plate from the concrete. After installation, the drywell liner was heated and expanded to compress the Firebar D to supply a gap between the steel drywell and the concrete. The gap prevents contact of the drywell wall with the concrete which might cause excessive local stresses during drywell expansion in a loss-of-coolant accident. The surveillance program is being conducted to demonstrate that the Firebar D will maintain its integrity and not deteriorate throughout plant life. The surveillance frequenc is adequate to detect any deterioration tendency of the material.yI The operability of the instrument line flow check valves are demonstrated to assure isolation capability for excess flow and to assure the operability of the instrument sensor when required.

Because of the large volume and thermal capacity of the suppression pool, the volume and temperature normally changes very slowly and monitoring these parameters daily is sufficient to establish any temperature trends. By requiring the suppression pool temperature to be continually monitored and also observed during periods of significant heat addition, the temperature trends will be closely followed so that appropriate action can be taken. The requirement for an external visual examination following any event where potentially high loadings could occur provides assurance that no significant damage was encountered. Particular attention should be focused on structural discontinuities in the vicinity of the relief valve discharge since these are expected to be the points of highest '

stress.

References (1) Licensing Application, Amendment 32, Question 3 (2) FDSAR, Volume I, Section V-1.1 (3) GE-NE 770-07-1090, "0yster Creek LOCA Drywell Pressure Response," February 1991 (4) Technical Safety Guide, " Reactor Containment Leakage Testing and

. Surveillance Requirements," USAEC Division of Safety Standards, Revised Draft, December 15, 1966.

(5) FDSAR, Volume I, Sections V-1.5 and V-1.6 (6) FDSAR, Volume 1, Sections V-1.6 and XIII-3.4 (7) FDSAR, Volume I, Section XIII-2 (8) Licensing Application, Amendment 11, Question III-18 OYSTER CREEK 4.5-16 Amendment No.: 7,27

,oj,.,

5.2 , CONTAINMENT

+ *. A. The primary containment shall be of the pressure suppression type having The a drywell drywell and an shall have absorption a volume chamber constructed of s180,000ft}

of approximately and eel.

conforms to the ASME Boiler and Pressure Vessel Code,Section VIII, for an internal pressure of 44 psig at 292 F and an external pressure of 2 psig at 150 F to 205*F. Theabsopptionchambershall have a total volume of approximately 210,000 ft . It is designed to conform to ASME Boiler and Pressure Vessel Code,Section VIII, for an internal pressure of 35 psig at 150*F and an external pressure of 1 psig at 150 F.

B. Penetrations added to the primary containment shall be designed in accordance with standards set forth in Section V-1.5 of the Facility Description and Safety Analysis Report. Piping passing through such penetrations shall have isolation valves in accordance with standards set forth in Section V-1.6 of the Facility Description and Safety Analysis Report.,

BASIS The drywell pressure of 44 psig is based upon a conservatively calculated peak drywell pressure of 38.1 psig plus an added 15% allowance. The calculated peak pressure results from a design basis loss of coolant accident (DBLOCA). The corresponding coincident drywell temperature of 292 F is the saturated steam temperature of the containment atmosphere for the 44 psig pressure. The specified coincident pressure and temperature condition represent the bounding case for the structural pressure / temperature design of the drywell.

t I

l 1

I l

l OYSTER CREEK 5.2-1 j l

l