NUREG-0433, Requests Proposal of Appropriate Preliminary Design Features & Procedures Suitable to Meet Lic Requirements as Listed in Staff Position on Cold shutdown(NUREG-0433)as Clarified in Encl

Requests Proposal of Appropriate Preliminary Design Features & Procedures Suitable to Meet Lic Requirements as Listed in Staff Position on Cold shutdown(NUREG-0433)as Clarified in Encl

ML20062D632
Person / Time
Site:	05000495
Issue date:	11/17/1978
From:	Heltemes C Office of Nuclear Reactor Regulation
To:	Kennedy W L STONE & WEBSTER, INC.
References
RTR-NUREG-0433, RTR-NUREG-433 NUDOCS 7811280134
Download: ML20062D632 (5)

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UNITED STATES 9

NUCLEAR REGULATORY COMMISslON g',j l

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WASHINGTON. D. C. 20556 3..

8 NOV 17137a f

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j Docket No. STN 50-495 7

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Mr. W. J. L. Kennedy, Vice President

'l Stone & Webster Engineering Corporation P. O. Box 2325 i-.

Boston, Massachusetts 02107 rg i

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Dear Mr. Kennedy:

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SUBJECT:

DESIGN REQUIREMENTS FOR SWESSAR-P1 REGARDING PLANT SHUTDOWM i

On May 31, 1978, we issued NUREG-0433, " Safety Evaluation Report -

J BSAR-205 Standard Design," which documented certain requirements for

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plant shutdown that would involve applicants referencing the Babcock l

& Wilcox (B&W) BSAR-205 design. A copy of this report was trans-mitted to Mr. B. G. Shultz, of Stone & Webster, with a copy of our letter of May 31, 1978 from Mr. Roger Boyd (NRC) to Mr. James Taylor (B&W),

Subject:

Issuance of Pr eliminary Design Approval.

The staff requirements, descrfoed on pages 5-21 ff. of NUREG-0433, were further clarified and discussed with B&W during the spring and 1 summer of 1978. Regarding the SWESSAR-Pl/BSAP,-205 plant design, we request that you propose appropriate preliminary design features and procedures suitable to meet licensing requirements as discussed in the enclosed staff position.

It is our intent to resolve this matter prior to issuance of a PDA for SWESSAR-Pl/BSAR405. Should you have any question about this request, please contact your licensing project manager, Thomas Cox, s.

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or myself directly.

, Sincerely, 5

Heltemes, '

, Chief S

ardization Branch Division of Project Management Office of Nuclear Reactor Regulation p

Enclosure:

l Staff Positicn on Cold Shutdown Requirements for SWESSAR-P1 t

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i Staff Position on Cold Shutdown Requirements for 6

i SWESSAR-Pl/BSAR-205 i

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.- l For each part of our cold shutdown position as expressed in NUREG-0433, l

-j pages 5-21 and 5-22, clarification, if necessary,'is provided as' follows:

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Provide safety-grade steam: generator dump valves, operators, l

air and power sup' plies which meet the single failure criterion.

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The staff position is that, for SWESSAR Pl/BSAR-205, local manual operation of the MADV's will not be acceptable. Operation from the i

il-p control room, for the time necessary to cool the plant to initiation

'I of the decay heat removal system, will be required.

It is assumed that the valve body, etc., is designed to seismic Category-I requirements i

and that operation could be achieved following a safe shutdown earthquake.

Provide the capability to cool down to cold shutdown in less

.s than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, assuming the most limiting single failure and with only offsite or onsite power available, or show that i

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manual actions inside or outside containment or return to hot i

standby until the manual actions or maintenance can be per-formed to correct the failure provides an acceptable alternative.

i The staff now requires that assuming the most limiting single failure, with only offsite or onsite power available and a safe shutdown earth-j-

quake, capability must exist to cool down to the decay heat removal

-l system cut-in conditions (rather than cold shutdown) in approximately p

36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

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l The staff position is that the current heat removal capacity is inadequate

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1 if this criterion cannot be met. B&W's calculations for BSAR-205 i

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f indicate that if one of the two available MAD valves is mechanically stuck closed, the plant cooldown time would be extended to at least i

several days., The staff considers this time excessive.. Accordingly, we require that additi'onal cooldown capability be provided. The addition l

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f of two MADV's (one more per steam generator) with the same capacity as 1

l the criginal valves would be an acceptable approach.

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Provide the capability to depressurize the reactor coolant I

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system with only safety-grade systems assuming a single failure and with only.offsite or onsite power available or show that i

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manual actions inside or outside containment or remaining at hot standby until manual actions or repairs are complete pro-t l

i vides an acceptable alternative.

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Provide the capability for boration with only safety-grade ~

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j systems assuming a single failure and with only offsite or i

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onsite power available, or show that manual actions inside I

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i or outside containment or remaining at hot standby until i

manual action or repairs are completed provides an acceptable l

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1 alternative.

i The staff considers it acceptable to stay at hot shutdown for the time 1

necessary to correct single failures, provided the overall cooldown -

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time to reach DHR cut-in conditions is approximately 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. In s

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providing the capability to decressuri::e and borate the reactor coolar' i

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s system, assuming a single failure and loss of offsite power, local operator action will be permitted to correct failures, if shown to be-i il acceptable (including consideration of accessibility of required cj equipment). Availability of nonseismic Category I equipment may not i

be assumed.

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The staff requires tha't the highest worth control rod is assumed at the fully withdrawn position when considering boration requirements.

l Conduct or reference approved prototype qualification tests

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to study the mixing of the added borated water and the cool-I I

down under natural circulation conditions with a worst-case single failure (i.e., a single failure of a steam generator l

1 atmospheric dump valve). These tests and analyses will be i

used to obtain information on cooldown times and the corres-s i

ponding antviliary feedwater requirements.

i A single prototype qualification test on the lead plant of a given j

design is acceptable. However, other tests might be required due to

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differences in system or component arrangement, procedural differences, l

new questions concerning accessibility or safety for manual actions,

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or other concerns not addressed by the initial prototype test.

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Provide specific procedures, at the operating license review stage, for cooling down using natural circulation, and submit f-j a summary outline of these procedures during the construction I

permit or preliminary design approval review.

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r Provide or require a seismic Category I auxiliary feedwater i

supply for at least four hours at hot shutdown plus cooldown

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i to the decay heat removal system cut-in based on the longest 1

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-I, time (for only onsite or offsite power and assuming the worst i

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l single failure), or show that an adequate altarnate seismic l

Category I source will be available.

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Meetings with Babcock and Wilcox did not indicate that clarification i

i of these parts of our position was necessary.

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