ML20031C573
| ML20031C573 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 09/30/1981 |
| From: | BOSTON EDISON CO. |
| To: | |
| Shared Package | |
| ML20031C566 | List: |
| References | |
| NUDOCS 8110070311 | |
| Download: ML20031C573 (6) | |
Text
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Technical Specification Change Containment Atmosphere Dilution (CAD) System Proposed Change Reference is made to Pilgrim Station Technical Specification Section 3.7. A
" Primary Containment", Item 3.7. A.5 "0xygen Concentration" Change:
A.) Item 3.7.A.5.c from " specification of 3.7. A cannot be met" to specification of 3.7.A.5 cannot be met" as shown on Page 157a attached.
Add:
Pages 157b,157c " Containment Atmosphere Dilution" Technical Specifications and Pages 171 and 171a " Post LOCA Atmosphere Dilution". Bases as shown on Pages 157b 157c, 171 and 171a attached.
Revisions of and additions to the existing Technical Specifications are designated by vertical lines located in the margin adjacent to the change.
Reason for Change Boston Edison was requested, in the NRC letter of June 26, 1981 from T. M. t'avak, to incorporate Technical Specifications for the " Containment Atmosphere Dilution (CAD) System. Model Technical Specifications have been used as a guide in the preparation. This submittal is to comply with your request.
Safety Considerations A safety evaluation has been done on the CAD system and it is not considered to constitute an unreviewed safety question. These changes have been reviewed and approved by the Operations Review Committee and reviewed by the Nuclear Safety Review and Audit Committee.
Schedule of Change This change will be put into effect upon Boston Edison's receipt of approval by the Comnission.
Fee Determination In accordance with Section 170.12 of the Commission's Regulations, Boston Edison proposes this change as a Class III since it involves a single safety issue.
Accordingly a check for Four Thousand Dollars ($4,000) is enclosed.
i 9110070311 810950 PDR ADOCK 05000293 1
P PDR
L1111 TING CONDITIONS FOR OPI: RATIO:1 SURVEli.T.ANCE RI'OlliRE}1ENTS 3.7 Primary Containnent 4.7 Prbary Cont.,fument b.
Within the 24-hour period subsequent to placing the reactor in the Run mode following a shutdown, the containment atmosphere oxygen concentration shall be reduced to 1 css than 5% by volume and maintnined
'.n this condition.
De-inerting m*y cocenence 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> prior to a shutdown.
l c.
If the specifications of 3.7.A.5 cannot be met, an orderly chutdown shall be initiated and the reactor shall be in a Cold Shutdown conditica within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
G e
e 5
e e
e 157a s.'.
)
LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7.A Primary Containment 4.7. A Primary Containment 6.
Containment Atmosphere 6.
Containment Atmosphere Dilution
- Dilution,
- a. Within the 24-hour a.
The post-LOCA contain-period subsequent to ment atmosphere dilu-placing the reactor in tion system shall be the Run McJe fLilowing functionally tested a shutdown, the Post-once per operating LOCA Containment cycle.
Atmosphere Dilution Sys-tem must be operable and capable of supply ~
ing nitrogen to the con-tainment for atmosphere dilution if required by Post-LOCA conditions.
If this specification cannot be met, the system must be restored to an operable condi-tion within 30 days or the reactor.must be in Cold Shutdown.
b.
Within the 24-hour b.
The level in the period subsequent to liquid Np storage placing the reactor in tank shall be recor-the Run Mode following ded weekly, a shutdown, the Post-LOCA Containment Atmosphere Dilution System shall contain a minimum of 1500 gallons of liquid N2 If this specification cannot be met the mini-mum volume will be re-stored within 30 days or the reactor must be in Cold Shutdown.
- c. Within the 24-hour c.
The CAD system H2
-period subsequent to analyzers shall be placing the reactor in tested for operability the Run Mode following using standard bottled a shutdown, there shall H2 once per month and be at least one CAD shall be calibrated system H2 analyzer once per 6 months.
available to serve
~
the drywell.
If this specification cannot be met, the unit shall be in Cold Shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
157b
LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3 7.A.S.
(Cont'd) 4.7.A.6.c (Cont'd)
Should one ~of the two H2 analyzers serving the drywell be found inoper-able the remaining analyzer of the same type serving the same compartment shall be tested for operability once per week until the defective analyzer is made operable, d.
Following the initial peak pressure of 45 psig, containment venting will be initiated via the SBGT system to the stack whenever the ccntainment re-pressurization reaches a maximum pressure of 28 psig and/or whenever the containment hydrogen concentration approaches 4%.
e 157c
BASES:
3.7. A & 4.7. A Primary Containment (Cont'd)
The primary containment is normally slightly pressurized during periods of reactor operation. Nitrogen used for inerting could leak out of the containment but air could not leak in to increase oxygen concentration. Once the containment is filled with nitro-gen to the required concentration, no monitoring of oxygen concen-tration is necessary.
However, at least twice a week the oxygen concentration will be determined as added assurance.
In conjunction with the Mark I Containment Short Term Program, a plant unique analysis (1) was performed which demonstrated a factor of safety of at least two for the vieakest element in the suppression chamber support system and attached piping. The maintenance of a drywell-suppression chamber differential pressure of 1.50 psid and a sup-pression chamber water level corresponding to a downcomer submergence range of 3.75 to 4.00 feet will assure the integrity of the suppression chamber when subjected to post-LOCA suppression pool hydrodynamic forces.
Post LOCA Atmosphere Dilution In order to ensure that the conta'nment atmosphere remains inerted, i.e. the oxygen-hydrogen mixture below the flammable limit, the capa-bility to inject nitrogen into the containment after a LOCA is pro-vided. During the first year of opeiation the normal inerting ni-trogen makeup system will be available for this purpose. After that time the specifically designed CAD s/ stem will serve as the post-LOCA Containment Atmosphere Dilution System. By maintaining a minimum of 1500 gallons of liquid N2 in the storage tank it is assured that a three-day supply of N2 for post-LOCA containment inerting is available.
Since the inerting makeup system is continually functioning, no periodic testing of the system is required. Twice weekly operation of the containment oxygen analyzer that is associated with the contain-ment inerting makeup system is sufficient to insure its readiness.
Reliance on that oxygen analyzer for this purpose of post-LOCA 02 measurement will terminate when the CAD system is operable.
The Post-LOCA Containment Atmospheric Dilution (CAD) System designed to meet the requirements of AEC Regulatory Guides 1.3,1.7 and 1.29, ASME Section III, Class 2 (except for code stamping) and seismic Class I as defined in the PNPS FSAR Section 12.2.3.5 and Section 2.5.3.
In summary, the limiting criteria are:
(1)
Plant Unique Analysis Report for Torus Support System and Attached Piping for Pilgrim Unit 1 Nuclear Power Station, Teledyne Technical Report No. TR 2255(a) dated August 5,1976.
171 1
2-1.
Maintain hydrugen concentration in the contain-ment during post-LOCA conditions to less than 4%.
2.
Limit the buildup in the containment pressure due to nitrogen addition to less than 28 psig.
3.
To limit the offsite dose due to containment venting (for' pressure control) to less than 300 Rem to the thyroid.
By maintaining at least a 3-day supply of N2 on site there will be sufficient time after the occurrence of a LOCA for ob w ning addi-tional nitrogen supply from local commercial sources.W The system design contains sufficient redundancy to ensure its reliabili-ty. Thus, it is sufficient to test the operability of the whole system once per operating cycle. The H2 analyzers will provide redundancy for the drywell 1.e., there are two H2 analyzers for d.e Unit. By permitting continued reactor operation at rated power with one of the two H2 analyzers inoperable, redundancy of analyzing capa-bility will be maintained while not imposing an unnecessary interrup-tion in plant operation.
If one of the two analyzers (H ) available 2
to serve the containment (drywell chamber) fails, the frequency of testing of the other analyzer of the same type available to serve the same compartment will be increased.from monthly to weekly to assure its continued availability. Monthly testing of the analyzers using bottled H2 will be adequate to ensure the system's readiness because of the design.
Since the analyzers are normally not in operation there will be little deterioration due to use.
In order to determine H2 concentration, the analyzers must be warmed up 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> prior to putting into service. This time frame is acceptable for accident conditions'because a 4% H2 level will not be reached in the drywell until 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> following the accident.
I Due to nitrogen addition, the pressure in the containment after a LOCA will increase with time. Under the worst expected conditions the contain-ment pressure will reach 28 psig in approximately 45 days.
If and when 5'
that pressure is reached, venting from the containment shall be manually initiated. The venting path will be through the Standby Gas Treatment system in order to minimize the off site dose.
(1), As listed in Pilgrim Nuclear Power Station Procedure No. 5.4.6 " Post Accident Venting".
171a