ML19329F416

RO 75-02:on 750810,long Lived Halogen & Particulate One Yr Release Rate Exceeded Design Objective 3.9.2.6.Corrections Not Required Because Prairie Island Tech Spechs More Conservative than Reg Guide 1.42,Revision 1,requirements

ML19329F416
Person / Time
Site:	Prairie Island, Midland
Issue date:	11/14/1975
From:	Watzl E NORTHERN STATES POWER CO.
To:
Shared Package
ML19329F414	List: ML19329F415 ML19329F416
References
NUDOCS 8006270462
Download: ML19329F416 (3)

Text

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November 14, 1975 e -

Supplement to License Event Report for Unusual Event 75-2 Identification of Event The rate of release of halogen and other particulate radioisotopes with half lives longer than 8 days, when averaged over a three-month period from May 11, 1975 through August 10, 1975, and when extrapolated at the same release rate for a year, was greater than two tbses Design Objective 3.9.2.b. .

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l Description of the Event . .

Data from the normal effluent surveillance testing program, from containment purge permits, and from gas decay tank release, permits 'are continually logged onto the l Effluent Release Survelliance File Cards (ERSFC). Each week particulate and charcoal l filters are changed from the continuous monitors on the Rad Waste Bldg Unit 1 and

! Unit 2 Auxiliary Bldg & Spent Fuel Pit Vents. These filters are analyzed and the

! effluents are quantified. .All releases from the containments and from gas decay tanks are sampled, analyzed and the effluents quantified.

j Analysis of the data from the ERSFC indicates that radioactivity released during the period from May 11, 1975 through August 10, 1975 was mostly I-131 and a smaller amount of co-58. Approximately 507 of the I-131 was released via the Rad Waste Bldg vent.

The remainder was released via the normal Auxiliary Bldg exhaust vents and from the j Unit 1 Contain=ent vent. Abnormal amounts of 1-131 and Co-58 were released from the i Unit I contain=ent during the week of June 30, 1975. This was the result of required i purging to permit maintenance.

I Analysis of the Event i

The period total wasradioactivity 1.07 x 10-2 with curies. h.alf lives greater than 8 days released during tge 13 wae This is an average release rate of 1.36 x 10~- Ci/sec.

The design objective annual average release rate for halogens and particulates is:

6,3 m3 /sec

.. i MPCi

,l where 91 = release rate (Ci/sec) of isotope i

MPCi = MPC for isotope i in column 1, Table II, l 10CFR20 The release during this period resulted in

'

0$ = 12.95 m3 /see i

MPC t which exceeds twice the design objective. This constitutes an Unusual Event in accordance with Technical Specification 3.9.B.1.a.

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/ November 14, l'3 / 5 r

_Recore for Unusua! Event 75-2 n't.

jupplement co_L_i_cinse Eve _

Corrective !.ction No correct)"e action is necessary. The current design objective release rate for long lived halog:.cs and particulates in gaseous celeases limits the concentration at the near, This is at least occupied re-1dence to less than 1/100,000 of the 10CFR20 requirenents.

a factor of five more conservative than the proposed NRC staff design objective for long lived halo .ans and particulates conservatively calculated using Regulatory Guide 1.42, Revision 1 " Interim Licensing Policy on As Low as ! Practicable for Gaseous Radioiodine

• Releases from Light-Water-Cooled Nucicar Power Reactors.

• 3 NSP requested a reevaluation of the current Technical Specification design gbjective for.

long lived halogens and particulates in a License ,' Amendment Request dated May 24, 1974 a:

in additional correspondence dated May 8,1975. In a letter dated August 15,1975 from Mr. G. L. Dicker, Chief, Environmental Projects Branch 2, Division of Reactor Licensing, USNRC, we were informed that any Technical Specifications changes relating to radioacti; cffluents will be deferred until NSP submits plans and proposed Technical Specificationr for keeping releases of radioactive effluents as low as practicable in accordance with t.

recently adopted Appendix I to 10CFR50. Guidance for submittal of this information by utilities has not yet been provided by the NRC Regulatory Staff.

When this release is evaluated using the conservative me'thodology of Regulatory Guide 1.l the annual extrapolated dose using the c:cisting critical pathway is approximately one third of the long lived iodine and particulate dese objective contained in Appendix I te 10CFR50. This estinate conservatively assumes dispersion factors applicable to a grount.

level release. This release does not, therefore, present a hazard na the health and safr of the public.

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